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Full text of "Our Living Resources: A Report to the Nation on the Distribution, Abundance, and Health of U.S. Plants, Animals and Ecosystem"

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A Report to the Nation on the 

Distribution, Abundance, and Health of 

U.S. Plants, Animals, and Ecosystems 



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U.S. Department of the Interior 
National Biological Service 



Our Living Resources 



PUBLIC DOCUMENTS 
DEPOSITORY ITEM 

OCT 4 1995 

CLEMSON 
LIBRARY 



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For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington DC ^0402 

Stock #024-010-00708-7 






Our Living Resources 

A Report to the Nation on the 

Distribution, Abundance, and Health of 

U.S. Plants, Animals, and Ecosystems 



Senior Science Editor and Project Director 

Edward T. LaRoe 

National Biological Sen'ice 



Managing Editor 
Gaye S. Farris 

National Biological Service 

Senior Technical Editor 

Catherine E. Puckett 

Johnson Controls World Services, Inc., and 
University of Southwestern Louisiana 

Graphics Editor 
Peter D. Doran 

Bureau of Land Management 
Science Editor 

Michael J. Mac 

National Biological Service 



U.S. Department of the Interior - National Biological Sen ice 

Washington, DC 
1995 



National Biological Service Cataloging-in-Publication Data 

Our living resources : a report to the nation on the distribution, abundance, and health of U.S. 
plants, animals, and ecosystems / Edited by Edward T. LaRoe ...[et al.] Washington. D.C. : U.S. 
Dept. of the Interior, National Biological Service, 1995. 530 p. : ill. ; 28 cm. Includes bibliograph- 
ical references and index. 

1. Biotic communities — United States. 2. Ecology — United States. 3. Animal populations — 
United States. 4. Plant populations — United States. 5. Natural resources — United States. 
I. LaRoe, Edward T. II. National Biological Service (U.S.) 
QH 104 .098 1995 



This report may be cited: 

LaRoe, E.T., G.S. Farris, C.E. Puckett, P.D. Doran, and M.J. Mac. eds. 1995. Our living resources: 
a report to the nation on the distribution, abundance, and health of U.S. plants, animals, and 
ecosystems. U.S. Department of the Interior, National Biological Service, Washington, DC. 
530 pp. 



Our I iving /u sum, ii 



The nation's biological resources are the 
basis of much of our current prosperity and 
an essential part of the wealth that we will pass 
on to future generations. Like other forms of 
wealth, biological diversity constitutes a 
resource that must be conserved and managed 
carefully. Proper management of any resource 
requires (1) inventorying and monitoring the 
resource, (2) understanding the factors deter- 
mining its supply and demand, and (3) analyz- 
ing options for current and future uses of the 
resource. Inventory and monitoring is the essen- 
tial first step in taking stock of the wealth rep- 
resented in our living resources and planning 
for their conservation and use. 

This report, Our Living Resources, is the 
first product of the Status and Trends Program 
in the National Biological Service. The report 
compiles, for scientists, managers, and the lay 
public, information on many species and the 
ecosystems on which they depend. As a first 
step toward a consistent, large-scale under- 
standing of the status and trends of these 
resources, this report brings together for the first 
time a host of information about our nation's 
biological wealth, highlighting causes for both 
comfort and concern. 

The report provides valuable information 
about causes for the decline of some species and 
habitats. It also gives insight into successful 
management strategies that have resulted in 
recovery of others. The report will also serve as 
a useful guide for identifying research needs by 
revealing information gaps that must be filled if 
we are to achieve a more comprehensive under- 
standing of both current conditions and the 
anticipated impact of change. 

The mission of the National Biological 
Service is to work with others to provide the 
information and technologies needed to manage 
and conserve the nation's biological resources. 
As the biological science arm of the Department 
of the Interior — with neither regulatory nor 
resource-management responsibilities — NBS 
has as its primary responsibility serving the bio- 
logical science needs of other Department of the 
Interior bureaus. 



NBS also lias a broader rule of working with 
other federal agencies, stales, universities, 
museums, private organizations, and landown- 
ers in a "National Partnership" to ensure that a 
more comprehensive and consistent approach is 
taken lo providing information about the 
nation's biological resources. All of the players 
in this new partnership have long and rich his- 
tories of collecting and interpreting biological 
information. The National Biological Service 
will work with its partners to supplement and 
integrate this scientific information and make it 
more accessible. 

Our Living Resources is a prime example of 
NBS's partnership approach. Authors are drawn 
from more than 15 federal agencies. 15 state 
agencies, 25 universities, and 13 private organi- 
zations. In some cases, individual papers are 
themselves products of interagency or intergo\ - 
ernmental partnerships. 

Statistically reliable information on the sta- 
tus and trends of biological resources is an 
essential step towards better stewardship of our 
nation's biological wealth. Equally important is 
an intensive research program aimed at under- 
standing what factors are responsible for bio- 
logical changes and the incorporation of that 
understanding into resource management and 
policy decisions. NBS works closely with 
resource managers and other decision makers to 
analyze how natural forces and human activities 
affect biological resources and to predict how 
alternative management and policy decisions 
might improve or degrade those resources. 

NBS is committed to providing better infor- 
mation and making that information easily 
accessible not only to those who manage and 
regulate how we use natural resources but also 
to every American who makes economic use or 
seeks recreation or simply cherishes the beauty 
of our living resources. More reliable informa- 
tion and better access to that information will 
result in better and fairer decisions and a more 
prosperous future for all Americans. 



Foreword 




H Ronald Pulliam 
Director, National Biological Service 



Our Living Resources 



Preface 



This report is the first of a series of reports on 
the status and trends of the nation's plants, 
animals, and ecosystems. It represents an effort 
to bridge the gap between scientists and 
resource managers, policy makers, and the gen- 
eral public. Usually, scientists tend to write for 
scientific journals and communicate with other 
scientists; this report attempts to collect a great 
variety of scientific data and interpret it for the 
nonscientist while maintaining the full credibil- 
ity of the data. 

The articles included represent both invited 
and contributed papers; that is, where we could 



identify specific subject experts, we invited 
them to submit papers, and we also accepted 
papers contributed by other authors. Following 
scientific tradition, each article submitted was 
peer-reviewed, usually by three anonymous sci- 
entific reviewers. The articles are often 
abridged from a complete scientific treatise, but 
each article contains references and personal 
contacts if the reader is interested in pursuing 
the subject in greater depth. Finally, we recog- 
nize that this report is incomplete and thai more 
status and trends data exist than we were able to 
uncover or incorporate into one volume. 



In Memoriam 




Edward Terhune LaRoe HI 



Senior science editor Ted LaRoe died of can- 
cer October 19, 1994, having shepherded this 
report almost to its completion. Had he lived to 
see Our Living Resources published, he would 
not have lingered to bask in its accomplishment. 
He would have moved on to new projects, new 
plateaus, for Ted always had a vision, a sense of 
where he was going. He also had a vision for the 
National Biological Service, which he was 
instrumental in helping to create. 

Ted was bright, creative, inquisitive, inspir- 
ing, and a man of many accomplishments. His 
scientific leadership was evident in his active 
role in issues relating to wetland science, glob- 
al climate change, coastal resources, ecosys- 
tem-based management, and, of course, NBS. 
Above all, he was a champion of scientific 
integrity, which, we trust, is evident in this 
report. We hope he would have been pleased. 



Our Living Resoun es 



We extend our sincere appreciation to all 
who helped produce this report. 
Especially important were the science editors — 
Austin K. Andrews, Raymond J. Boyd, Glenn 
R. Guntenspergen, Russell J. Hall, Michael D. 
Jennings, Hiram W. Li, Michael J. Mac, 
William T. Mason, Jr., O. Eugene Maughan, 
Roy W. McDiarmid, Carole C. Mclvor, J. 
Michael Scott, William K. Seitz, Thomas J. 
Stohlgren, Benjamin N. Tuggle, Wayne A. 
Willford, and Gary D. Willson. They served by 
coordinating reviews, including the peer 
reviews of articles within their sections. In addi- 
tion, they each provided an overview to the 
material in their sections. Assisting with 
overviews were Gregor T. Auble and B.D. 
Keeland. 

Carl Anderson, Michalann Harthill, Deborah 
E. Peck, Helen V. Turner, and Sherri L. Hendren 
each provided tremendous technical support. 
Contributing expertise in graphics were 
Nicholas R. Batik, Mary A. Helmerick, Dave 
Opp, Diane K. Baker, Janine J. Koselak, and M. 
Jennifer Kapus. Technical editors — Mary 
Catherine Hager, Beverly Kerr-Mattox, and 
Kristie A. Weeks — dedicated months to the 



editing of individual articles. Technical typists 
Deany M. Cheramie, Dana M. Cm rod. and 
Tiffany Alexander Hall assisted by keyboard- 
ing. correcting, and proofreading. Technical 
typist Judy Zabdyr helped in the final stages as 
did proofreaders Rhonda F. Davis and Lori E. 
Huckaby, under the direction of editor Beth A. 
Vairin, who also reviewed the report Librarian 
Judy K. Buys performed numerous bibliograph- 
ic searches to verily citations, and Marilyn 
Rowland indexed the report. Robert E. Stewart. 
Director of the National Biological Service's 
Southern Science Center, graciously allowed 
the use of his staff, space, and equipment to pro- 
duce this report, as did Lawrence Bembry, 
Director of the Bureau of Land Management's 
Service Center. We are also grateful to all those 
who gave permission to use their slides and 
graphics. 

Finally, we would like to thank the authors, 
the peer reviewers, and the state, federal, and 
private agencies who so willingly gave of their 
time and data. Without their hard work and 
cooperation, this report would not have been 
possible. 



Acknowledg- 
ments 



Our Living Resources 



Contents 




Foreword v 

Preface vi 

In Memoriam vi 

Acknowledgments vii 

Part 1 Introduction 

Overview 3 

Biodiversity: A New Challenge 6 

Conservation Landmarks: Bureau of Biological Survey and National Biological Service .... 7 
Activities of the Bureau of Biological Survey 8 

Part 2 Distribution, Abundance, and Health 

Species — - ----^^^^^— — 1^^^^^^^^^_ _-~~____________— ____^-^__-_- 

Birds 

Overview 15 

Breeding Bird Survey: Population Trends 1966-92 17 

Winter Population Trends of Selected Songbirds 21 

Breeding Productivity and Adult Survival in Nongame Birds 23 

Canada Geese in North America 26 

Canada Geese in the Atlantic Flyway 28 

Arctic Nesting Geese: Alaskan Populations 30 

North American Ducks 34 

Decline of Northern Pintails 38 

Canvasback Ducks 40 

Breeding Seabirds in California, Oregon, and Washington 43 

Seabirds in Alaska 49 

Colonial Waterbirds 53 

Shorebirds: East of the 105th Meridian 57 

Western North American Shorebirds 60 

Raptors 65 

Causes of Eagle Deaths 68 

Return of Wild Turkeys 70 

Mourning Doves 71 

Common Ravens in the Southwestern United States, 1968-92 73 

Mississippi Sandhill Cranes 75 

Piping Plovers 77 

California Condors 80 

Audubon's Crested Caracara in Florida 82 

Puerto Rican Parrots 83 

Red-cockaded Woodpeckers 86 

Southwestern Willow Flycatchers in the Grand Canyon 89 

Mammals 

Overview 93 

Marine Mammals 94 

Indiana Bats 97 

Gray Wolves 98 

Black Bears in North America 100 

Grizzly Bears 103 

Black-footed Ferrets 1 06 

American Badgers in Illinois 108 

California Sea Otters 110 

White-tailed Deer in the Northeast 112 

Deer Management at Parks and Refuges 113 

North American Elk 1 15 

Reptiles and Amphibians 

Overview 117 

Turtles 118 

Marine Turtles in the Southeast 121 



Our living Resoun ei 



Amphibians p^ 

A Success Story: The Barton Springs Salamander 125 

American Alligators in Florida P7 

Reptiles and Amphibians in the Endangered Longleaf Pine Ecosystem ... ' 129 

Native Ranid Frogs in California \-\\ 

Desert Tortoises in the Mojave and Colorado Deserts 1 35 

Coachella Valley Fringe-toed Lizards [37 

Disappearance of the Tarahumara Frog 1 3X 

Fishes 

Overview 141 

Imperiled Freshwater Fishes 142 

Southeastern Freshwater Fishes 1 44 

Loss of Genetic Diversity Among Managed Populations 147 

Colorado River Basin Fishes 149 

Cutthroat Trout in Glacier National Park, Montana 153 

Columbia River Basin White Sturgeon [54 

Invertebrates 

Overview .159 

Diversity and Abundance of Insects 1 6 1 

Grasshoppers I (-,3 

The Changing Insect Fauna of Albany's Pine Barrens 166 

Lepidoptera in North America 168 

Fourth of July Butterfly Count 171 

Species Richness and Trends of Western Butterflies and Moths 172 

The Tall-grass Prairie Butterfly Community 174 

The Biota of Illinois Caves and Springs 1 76 

Freshwater Mussels: A Neglected and Declining Aquatic Resource 177 

Freshwater Mussels in Lake Huron-Lake Erie Corridor 179 

Aquatic Insects As Indicators of Environmental Quality 1 S2 

Biodiversity Degradation in Illinois Stoneflies 184 

Plants 

Overview 189 

Microfungi: Molds, Mildews, Rusts, and Smuts 190 

Macrofungi 192 

Truffles, Trees, and Biodiversity 193 

Lichens 194 

Bryophytes 1 97 

Floristic Inventories of U.S. Bryophytes [98 

Vascular Plants of the United States 200 

Environmental Change and the Florida Torreya 205 

Native Vascular Plants 205 

Tracking the Mosses and Vascular Plants of New York ( 1 836-1994) 209 



Ecosystems , 



Terrestrial Ecosystems 

Overview 213 

U.S. Forest Resources 214 

Southern Forested Wetlands 216 

Rare Terrestrial Ecological Communities of the United Stales 2 I s 

Altered Fire Regimes Within Fire-adapted Ecosystems 222 

Vegetation Change in National Parks 224 

Air Pollution Effects on Forest Ecosystems in North America 227 

Air Quality in the National Park System 

Whitebark Pine: Ecosystem in Peril 22S 

Oak Savannas in Wisconsin 230 

Aquatic Ecosystems 

Overview 

Habitat Changes in the Upper Mississippi River Floodplain 234 

Biota of the Upper Mississippi River Ecos) stem 236 




Our Living Resources 



Fish Populations in the Illinois River 239 

Contaminant Trends in Great Lakes Fish 242 

Lake Trout in the Great Lakes 244 

Wetlands in Regulated Great Lakes 247 

Decline in the Freshwater Gastropod Fauna in the Mobile Bay Basin 249 

Protozoa 252 

Marine and Freshwater Algae 255 

Freshwater Diatoms: Indicators of Ecosystem Change 256 

Coastal and Marine Ecosystems 

Overview 259 

Nearshore Fish Assemblage of the Tidal Hudson River 260 

Natural Resources in the Chesapeake Bay Watershed 263 

Florida Manatees 267 

Gulf of Mexico Coastal Wetlands: Case Studies of Loss Trends 269 

Seagrass Distribution in the Northern Gulf of Mexico 273 

Seagrass Meadows of the Laguna Madre of Texas 275 

Coastal Barrier Erosion: Loss of Valuable Coastal Ecosystems 277 

Reef Fishes of the Florida Keys 279 

Coral Reef Ecosystems 280 

Riparian Ecosystems 

Overview 285 

Western Riparian Ecosystems 286 

Surface Cover Changes in the Rio Grande Floodplain, 1935-89 290 




Ecoregions 



The Great Plains 

Overview 295 

Declining Grassland Birds 296 

Migratory Bird Population Changes in North Dakota 298 

Duck Nest Success in the Prairie Potholes 300 

Conservation Reserve Program and Migratory Birds in the Northern Great Plains 302 

Decline of Native Prairie Fishes 303 

The Coyote: An Indicator Species of Environmental Change on the Great Plains 305 

Interior West 

Overview 309 

Ecosystem Trends in the Colorado Rockies 310 

The Greater Yellowstone Ecosystem 312 

Subalpine Forests of Western North America 314 

Southwestern Sky Island Ecosystems 318 

Endangered Cui-ui of Pyramid Lake, Nevada 323 

Bonytail and Razorback Sucker in the Colorado River Basin 324 

Amphibian and Reptile Diversity on the Colorado Plateau 326 

Wintering Bald Eagles Along the Colorado River Corridor 328 

Mexican Spotted Owls in Canyonlands of the Colorado Plateau 330 

Bighorn Sheep in the Rocky Mountain National Parks 332 

Desert Bighorn Sheep 333 

Alaska 

Overview 337 

The Arctic Tundra Ecosystem in Northeast Alaska 338 

Anadromous Fish of the Central Alaska Beaufort Sea 341 

Pacific Salmon in Alaska 343 

Wolves and Caribou in Denali National Park, Alaska 347 

Kodiak Brown Bears 349 

Polar Bears in Alaska 351 

Sea Otters in the North Pacific Ocean 353 

Pacific Walruses 356 

Mentasta Caribou Herd 357 

Tundra or Arctic Hares 359 



Our Living Resoun es a 



Hawaii 

Overview 361 

Hawaii Biological Survey 362 

Haleakala Silversword 353 

Insects of Hawaii 355 

Drosophila as Monitors of Change in Hawaiian Ecosystems 368 

Birds of Hawaii 372 

Hawaii's Endemic Birds 376 

Part 3 Special Issues 

Global Climate Change 

Overview 3X5 

Changes in Winter Ranges of Selected Birds, 1901-89 386 

Changes in Nesting Behavior of Arctic Geese 388 

Climate Change in the Northeast 390 

Potential Impacts of Climate Change on North American Flora 392 

Human Influences 

Overview 397 

Significance of Federal Lands for Endangered Species 398 

Status of U.S. Species: Setting Conservation Priorities 399 

Increased Avian Diseases With Habitat Change 401 

Captive Propagation, Introduction, and Translocation Programs for Wildlife Vertebrates. . . 405 

Raccoon Rabies: Example of Translocation, Disease 406 

Contaminants in Coastal Fish and Mollusks 408 

Persistent Environmental Contaminants in Fish and Wildlife 413 

Wildlife Mortality Attributed to Organophosphorus and Carbamate Pesticides 416 

Acidic Deposition ("Acid Rain") 418 

Atmospheric Deposition and Solute Transport in a Montane Mixed-Conifer Forest System 421 
Agricultural Ecosystems 423 

Non-Native Species 

Overview 427 

Non-native Aquatic Species in the United States and Coastal Waters 428 

Nonindigenous Fish 43 1 

Non-native Reptiles and Amphibians 433 

Non-native Birds 437 

Non-native Animals on Public Lands 440 

Exotic Species in the Great Lakes 442 

Zebra Mussels in Southwestern Lake Michigan 445 

Invasion of the Zebra Mussel in the United States 445 

Africanized Bees in North America 448 

Bullfrogs: Introduced Predators in Southwestern Wetlands 452 

Invasions of the Brown Tree Snake 454 

Wild Horses and Burros on Public Lands 456 

Purple Loosestrife 458 

Habitat Assessments 

Overview 46 1 

GAP Analysis: A Geographic Approach to Planning for Biological Diversity 462 

Protection Status of Vegetation Cover Types in Utah 463 

Biodiversity in the Southwestern California Region 465 

Federal Data Bases of Land Characteristics 467 

Monitoring Changes in Landscapes from Satellite Imagery 468 

Landsat MSS Images 470 

The Nation's Wetlands 473 

Glossary 479 

Index 483 




'ii'o " * 




\ 


PARTI 


ImlMBImiM 






Sp^- 




Introduction 



Overview 



This report on the distri- 
bution, abundance, and 
health of our nation's biological resources is the 
first product of the National Biological 
Service's Status and Trends Program. This 
information has many potential uses: it can 
document successful management efforts so 
resource managers will know what has worked 
well; it can identify problems so managers can 
take early action to restore the resource in the 
most cost-efficient manner; and it can be used to 
highlight areas where additional research is 
needed, such as to determine why certain eco- 
logical changes are occurring. This report will 
also be useful to teachers, students, journalists, 
and citizens in general who are interested in 
national resource issues. 

Another purpose of this report is to help 
identify gaps in existing resource inventory and 
monitoring programs. It contains information 
collected by a variety of existing research and 
monitoring efforts by scientists in the National 
Biological Service, other federal and state agen- 
cies, academia, and the private sector. The pro- 
grams that produced the information in this doc- 
ument were not developed in a coordinated 
fashion to produce an integrated, comprehen- 
sive picture of the status and trends of our 
nation's resources; rather, each was developed 



for its own particular purpose, usually to help 
manage a specific resource. Thus, even though 
articles vary greatly in scope, design, and pur- 
pose, this report has identified and attempted to 
combine many of the existing information 
sources into a broad picture of the condition of 
our resources. In the future, these sources will 
be complemented by additional information 
from other sources — such as state agencies and 
other inventory and monitoring studies — to fill 
in the gaps of knowledge and to provide a more 
complete understanding of the status of our liv- 
ing resources. 

A second report, to be released by the 
National Biological Service in 199?. will use 
the information contained in ihis report and data 
from other sources to provide a synthesized 
account of the status and trends of the nation's 
biodiversity. It will discuss from a historical 
perspective the factors influencing biodiversity, 
both natural and human-induced, and provide 
an integrated description of the Status and trends 
of biological resources on a regional basis 

Status and Trends 

The goal of inventory and monitoring pro- 
grams is to determine the status and trends of 

selected species or ecoss stents. Status studies 



uy 

Edward T. LaRoe 

Senior Science Editor am 

Project Director 

National Biological 
Service 



Introduction — Our Living Resources 



Figure. Northern pintail duck 
[Anas acuta) population data 
demonstrate the importance of 
long-term data sets. Annual fluctu- 
ations (e.g.. 1967-70 ) reflect year- 
ly fluctuations in breeding success 
that may have been caused, for 
example, by differences in rainfall 
and the abundance of temporary 
wetlands for nesting habitat. 
Short-term data sets can give erro- 
neous conclusions; for example, if 
only data from 1964 to 1972 were 
available, managers might con- 
clude that populations were 
increasing. The long-term data, 
however, describe a statistically 
and biologically significant popu- 
lation decline. (Source: U.S. Fish 
and Wildlife Service. 1993. Status 
of Waterfowl and Fall Flight 
Forecast.) 



produce data on the condition of species or 
ecosystems for a single point in time; trend 
studies, in contrast, provide a chronological or 
geographic picture of change in the same 
resource. Either can measure a number of dif- 
ferent biological indicators, such as population 
size, distribution, health, or physiological fac- 
tors such as breeding productivity or seed pro- 
duction. Species composition, biodiversity, and 
age and physical structure are all important 
indicators of ecosystem status. 

Inventory and monitoring programs can pro- 
vide measures of status and trends to determine 
levels of ecological success or stress; if such 
programs are appropriately designed, they can 
give early warnings of pending problems, 
allowing resource managers to take remedial 
action while there are more management 
options. These earlier options are less severe 
than if management response is delayed until 
problems are critical, such as when a species 
becomes endangered. 

One of the challenges resource managers 
face is to detect long-term trends because such 
trends are often masked by short-term, random, 
or undirectional variations (Figure). Plant and 
animal species often vary greatly in abundance, 
distribution, or fecundity as a result of forces 
that include annual or seasonal variations in cli- 
mate; chance events such as floods and hurri- 
canes; effects from predators or competing 
species; and even internal physiological 
processes. Some variations appear totally ran- 
dom; many are cyclic, recurring periodically; 
and others are long-term in one predominant 
direction. Scientists have many ways to deter- 
mine whether apparent changes are biologically 
and statistically significant, although it is often 
difficult to detect such trends in their early 
stages. The design of monitoring programs 
should address issues such as the number of 
samples needed, the sampling technique, and 
the frequency and duration of sampling. All are 
critical factors in determining the sensitivity of 
the monitoring program to detect directional 




OfTT 
55 



60 



65 



70 



75 
Year 



85 



90 



change. Data collected in a standard or consis- 
tent fashion over many years are especially crit- 
ical to identify and document trends. 

National Inventory and 
Monitoring Programs 

A number of inventory and monitoring pro- 
grams have been underway for several to many 
years in various agencies (Table). Historically, 
the federal government has been responsible for 
monitoring the status and trends of migratory 
species as well as those resident on federal 
lands. In addition, the federal government mon- 
itors habitat conditions on federal lands and, 
under some circumstances, private lands. Some 
of the monitoring programs also require 
international cooperation because many of the 
migratory species monitored cross international 
boundaries. 

States have monitored resident species and 
often cooperated in surveys of migratory 
species. A significant problem with these efforts 
has been that often the individual agencies or 
states have used different monitoring proce- 
dures and standards, and the results are not 
comparable from area to area or among differ- 
ent agencies. 

The private sector, including particularly 
The Nature Conservancy, has worked with 
states to establish Heritage Programs that mon- 
itor the distribution and abundance of selected 
species. This effort has resulted in standardized 
procedures. 

Most inventory and monitoring programs 
were established for a specific purpose, usually 
relating to management of natural resources. 
For example, the efforts to monitor duck popu- 
lations started 35 years ago to improve the basis 
for hunting regulations, and the National 
Wetland Inventory was started in 1979 to deter- 
mine the condition and rate of wetland loss. 
Until recently, few, if any, of these programs 
were intended or have been used to provide 
broad-based and predictive tools that could help 
resource managers identify future resource 
problems. 

The National Biological Service has the 
responsibility for developing information on the 
status and trends of our nation's plants and ani- 
mals and the habitats on which they depend. It 
will achieve this by building on the inventory 
and monitoring activities existing in the state, 
federal, and private sectors. The national status 
and trends effort will continue to depend upon 
the contributions of these existing programs, 
and NBS will avoid duplicating programs 
already under way. Its role will be to coordinate 
the activities of different agencies into a com- 
prehensive assessment of our living resources. 



Our Living Resoun e& Introdm tion 



continuing its own contributions, and when nec- 
essary, supplementing the current array of activ- 
ities. 

Organization of This Report 

In addition to this overview, the report intro- 
duction includes articles on the importance of 
biodiversity and a historical look at biological 
study in the federal government. 

The articles that follow, contributed by a 
variety of authors and agencies, represent the 
first effort to pull together information on the 
status and trends of different groups of biota, 
ecosystems, and ecoregions as well as related 
issues. Individual articles in each section are 
most often arranged from the most general or 
large scale, to the most specific or small scale. 
The organization is somewhat arbitrary in that 
many articles could appear with equally valid 
justifications in several different locations. 

Animals and Plants 

Not all groups have received equal treat- 
ment, in large part because our current knowl- 
edge is not equal among all groups, and inven- 
tory and monitoring are focused on compara- 
tively few species. Scientific studies have been 
greatly assisted in some areas by the work of 
natural historians and public volunteers. Bird 
watchers, butterfly collectors, and shell collec- 
tors, for example, have provided invaluable sci- 
entific information about the geographic ranges 
of groups in which they are interested. Some of 
the professional societies today owe their ori- 
gins to the efforts of amateurs to organize and 
improve their understanding of biota. 

Many of the less visible or charismatic taxa 
lack the scientific effort or information, much 
less the volunteer amateur support, to discuss 
trends in their abundance or distribution. The 
very title "Animals and Plants" could be viewed 
as biased by some biologists; although most of 
the public views mushrooms and other fungi as 
plants, specialists consider them a separate 
kingdom, equal both taxonomically as well as 
in ecological significance to both plants and 
animals. Despite their significance, plants are 
simply underrepresented in this report because 
the data are lacking. 

The report begins with birds, the single 
group for which we have the most data at 
national and large-scale levels. Because of the 
significance of birds as important migratory 
species, there has been a strong role for federal 
research scientists as well as scientists from 
state agencies and from Canada and Mexico. 
Some of the best long-term scientific informa- 
tion on status and trends comes from the 
Breeding Bird Survey and the Christmas Bird 
Count. 



Table. Selected examples ol existing ecological inventor) and monitoring programs 



Subject 


Institution 


Migratory bird surveys 


Breeding birds 


National Biological Service (NBS) 


Wintering birds 


The Audubon Society 


Waterfowl surveys 


U.S. Fish and Wildlife Service (USFWS), NBS. and states, with inter- 
national participation 


Rare and threatened species 


Listed endangered and threatened species 


States, U.S. federal land managers (e.g., National Park Service. 
Bureau of Land Management (BLM), U.S. Forest Service (USFS)), 
USFWS, NBS 


State Heritage Programs 


State agencies and The Nature Conservancy 


Endangered marine species 


National Marine Fisheries Service (NMFS) 


Resident game species 


(e.g., deer, turkey, furbearers) 


State fish and wildlife conservation agencies 


Habitats and biological communities 


National Wetlands Inventory 


USFWS 


Gap Analysis Program 


NBS in partnership with states and private sector 


Environmental Monitoring and Assessment Program 


U.S. Environmental Protection Agency 


Resources Conservation Act, inventory of wildlife 
and habitat conditions of farmlands 


U.S. Soil Conservation Service (now Natural Resources Conservation 
Service) 


Wildlife and habitat on public lands 


Resources Planning Act assessment of 
USFS lands 


USFS 


Federal Land Policy and Management Act 
assessment of BLM lands 


BLM 


Contaminants 


Aquatic and terrestrial (Biomonitoring of Environmental NBS with USFWS; U.S. Geological Survey 
Status & Trends National Water Quality Assessment) 


Marine and coastal 


National Oceanic and Atmospheric Administration and NMFS 



Ecosystems and Ecoregions 

We have also included information on 
ecosystems and ecoregions. Ecosystems are 
groups of plants and animals and their nonliving 
environment such as air and water. For example, 
one can speak of a coastal wetland ecosystem, 
whether in North Carolina or Florida, and 
understand that it includes several specific fea- 
tures or processes shared by all coastal wetland 
ecosystems. 

Ecoregions are geographically defined eco- 
logical units, often containing several types of 
ecosystems, that share common topographic, 
climatic, and biotic characteristics. Each ecore- 
gion, such as Alaska or Hawaii, can be defined 
as a single, individual unit on a map. while 
ecosystems, if mapped, would be scattered 
about as separate units. 

Special Issues 

After the status and trends of animals and 
plants, ecosystems, and ecoregions are present- 
ed, a section on related issues follows: global 
climate change, human influences, non-name 
species, and methods of habitat assessment. I he 
proliferation of introduced species, both plant 
and animal, has had a profound influence on the 
native biota of this country. Main human activ- 
ities, such as pollution and urbanization, both 
directly and indirectly affect the health of our 
living resources. The possibilities ol global cli- 
mate change are examined, followed by a briel 



Introduction — Our Living Resources 



overview of national programs such as the Gap 
Analysis Program, which scientists hope will 
prove useful in acquiring data to help resource 



policy makers better protect our resources. 



Biodiversity: 

A New 
Challenge 



by 

Edward T. LaRoe 
National Biological Service 



Resource managers at many state and federal 
agencies are in the middle of a fundamental 
change in the practice and objectives of conser- 
vation. Traditional management has been 
directed toward maintaining, usually for harvest 
purposes, populations of individual species 
such as ducks, deer, or salmon. Increasingly, 
however, resource managers are recognizing the 
critical importance of conserving biological 
diversity, or biodiversity. 

In its simplest terms, biological diversity is 
the variety of life at all levels: it includes the 
array of plants and animals; the genetic differ- 
ences among individuals; the communities, 
ecosystems, and landscapes in which they 
occur; and the variety of processes on which 
they depend. Conserving biological diversity 
poses dramatic new problems for comprehen- 
sive inventory and monitoring: what should be 
measured or monitored? 

Biodiversity is important for many reasons. 
Its value is often reported in economic terms: 
for example, about half of all medicinal drugs 
(Keystone Center 1991; Wilson 1992) come 
from — or were first found in — natural plants 
and animals, and therefore these resources are 
critical for their existing and as yet undiscov- 
ered medicinal benefits. Additionally, most 
foods were domesticated from wild stocks, and 
interbreeding of different, wild genetic stocks is 
often used to increase crop yield. Today we use 
but a small fraction of the food crops used by 
Native cultures: many of these underused plants 
may become critical new food sources for the 
expanding human population or in times of 
changing environmental conditions. 

But biodiversity has an even greater impor- 
tance: it is the great variety of life that makes 
existence on earth possible. As a simple exam- 
ple, plants convert carbon dioxide to oxygen 
during the photosynthetic process: animals 
breathe this fresh air, releasing energy and pro- 
viding the second level of the food chain. In 
turn, animals convert oxygen back to carbon 
dioxide, providing the building blocks for the 
formation of sugars during photosynthesis by 
plants. Microbes (fungi, bacteria, and proto- 
zoans) break down the carcasses of dead organ- 
isms, recycling the minerals to make them 
available for new life; along with some algae 
and lichens, they create soils and improve soil 
fertility. 

Biodiversity provides the reservoir for 
change in our life-support systems, allowing 
life to adapt to changing conditions. In a natur- 
al population, for example, some individuals 
will be more resistant to drought or disease or 



cold; as the environment changes, from season 
to season, year to year, or over longer periods, 
and as plagues come and go, these differences 
among individuals allow at least some members 
of the population or species to survive and 
reproduce. This diversity is the basis not only 
for short-term adaptation to changing condi- 
tions, but also for long-term evolution as well. 

Like air, water, and soils, biological diversi- 
ty is part of the capital upon which all life 
depends. The need for this diversity is greatest 
in times of environmental stress when plants, 
animals, and microbes must develop new char- 
acteristics or strategies for survival. As we look 
at the problems of the globe today — global cli- 
mate change, decreases in the ozone shield and 
increasing ultraviolet radiation, losses of natur- 
al habitats, and pervasive pollution in our 
streams and oceans — we must recognize that 
we, as a form of life on earth, need the ability to 
change in order to cope with new stresses. 

Humans cannot survive in the absence of 
nature. We depend on the diversity of life on 
earth for about 25% of our fuel (wood and 
manure in Africa, India, and much of Asia); 
more than 50% of our fiber (for clothes and 
construction); almost 50% of our medicines; 
and, of course, for all our food (Miller et al. 
1985). As previously stated, biodiversity pro- 
duces other benefits: plants produce oxygen for 
our atmosphere; microbes break down wastes, 
recycle nutrients, and build the fertility of our 
soils. One reason our highways are not littered 
with the carcasses of dead dogs, cats, skunks, 
armadillos, and deer is biodiversity, in the form 
of the many scavengers and microbes that we 
don't often think about, but which play an 
essential role in the cycle of life. Even species 
often viewed as "repulsive," such as vultures 
and maggots, play critical roles in our lives. 

Some people believe that because extinction 
is a natural process, we therefore should not 
worry about endangered species or the loss of 
biodiversity. Certainly extinction is natural; it 
usually occurs as newer forms of life evolve. 
But under the forces of population growth, tech- 
nology, and special interests, humans have dri- 
ven the rate of extinctions today to about 100 
times — two orders of magnitude — the natural 
rate. Even worse, the rate of extinction is still 
increasing and will be 100 to 1,000 times faster 
yet in the next 55 years (Miller et al. 1985); sci- 
entists today predict that between now and 
2030, half the expected lifetime of a child born 
today, the Earth will lose between a quarter and 
a third of all existing species. And this is in the 
absence of new forms of life to replace them. 



Our living Resources Introdui nan 



The last time Earth lost this large a share of its 
life was 65 million years ago when it may have 
collided with an asteroid; the impacts of 
humans on our planet today may have been last 
equaled by the collision of two heavenly bodies 
(Wilson 1992). 

Scientists cannot honestly say that we need 
all species thai exist today for humans to sur- 
vive; but as a general rule, the more diversity is 
diminished, the less stable ecosystems become 
and the greater the fluctuations that occur in 
plant and animal populations. The more diversi- 
ty we lose, the more our quality of life and eco- 
nomic potential are diminished, and the greater 
the risk that we will cause a critical part of the 
cycle of life to fail. 

If humans were allowed to cause the extinc- 
tion of other species, who would determine 
which species? If we had been asked 60 years 
ago what life we could let become extinct, who 



among us would have insisted that we preserve 
the lowly mold that was penicillin, the first of 
the series of antibiotics that have today so 
changed the quality of our lives? And who, 
only 5 years ago, would have identified the need 
to preserve the Pacific yew, which today yields 
taxol, one of the greatest new hopes in our arse- 
nal against cancer'.' 

References 

Keystone Center. 1991. Biological diversity on federal 
lands, report of a Keystone policy dialogue. The 
Keystone Center. Keystone, CO. 96 pp. 

Miller, K.R., J. Fortado, C. De Klemm, J. A. McNeely. N. 
Myers. M.E. Soule. and M.C. Trexler. [985. Issues on the 
preservation of biological diversity. Pages 337-362 in 
Robert Repetto. ed. The global possible. Yale University 
Press, New Haven. 

Wilson, E.O. 1992. The diversity of life. Belknap Press ol 
Harvard University Press. Cambridge. MA. 424 pp. 



A century separates the recent development 
of the National Biological Service (NBS) 
and an early predecessor, the Bureau of 
Biological Survey (BBS). Both organizations 
were established at critical crossroads for the 
conservation of the nation's living biological 
resources and are conservation landmarks of 
their times. The BBS of the 1920's was 
described as "a government Bureau of the first 
rank, handling affairs of great scientific, educa- 
tional, social, and above all, economic impor- 
tance throughout the United States and its out- 
lying possessions" (Cameron 1929:144-145). 
This stature was achieved at a time of great 
social, economic, and ecological change. BBS 
had the vision to pioneer new approaches that 
led to enhanced understanding of the relation 
between people, other living things, and the 
environment. The NBS faces similar challenges 
to address the issues of the 1990's and beyond. 

Diminished Natural Resources 
in a World of Plenty 

Early European colonists had an abundance 
of wildlife to serve subsistence needs. 
Seemingly endless flocks of ducks, geese, and 
swans; an abundance of wild turkeys, deer, and 
bison; green clouds of Carolina parakeets and 
millions of passenger pigeons; and a bounty of 
fish and shellfish. This abundance quickly 
established a viewpoint that the New World's 
wildlife resources were inexhaustible. 

Habitat changes that disrupted the balance of 
nature soon resulted in economic losses and 
other hardships because of insect and rodent 
eruptions. Negative effects of exotic species 



brought from the Old World further reduced the 
well-being of many colonists who had come to 
the New World for a better life. The nation's 
inexhaustible natural resources and returns from 
agriculture began to wane significantly. 
Decimation of previously vast wildlife 
resources greatly reduced opportunities for cul- 
tural and recreational uses of wildlife (Cameron 
1929). 

Development of the BBS 

Roots of the BBS can be traced to the 1 883 
founding of the American Ornithological Union 
(AOU) in New York City. Initially, the AOU 
focused on three subject areas — distribution, 
biological information and economic impact, 
and migratory behaviors of birds — all of which 
became major activities of the BBS. 
Collaborations and partnerships were developed 
with numerous ornithologists, field collectors, 
sportsmen, and observers of nature who were 
asked to report specific information relative to 
bird migration. Cooperation also was obtained 
from the United States Lighthouse Board and 
the Department of Marine and Fisheries of 
Canada (Cameron 1929). 

Funds for government biological survey pro- 
grams related to economic ornitholog) were 
allocated in 1885 to the Division of Entomology 
of the U.S. Department of Agriculture. These 
funds were provided for "the promotion of eco- 
nomic ornithology, or the study ol the interrela- 
tion of birds and agriculture, an investigation of 
the food habits, and migration of birds in rela- 
tion to both insects and plains." The following 
year additional funds were provided to include 
the study of mammals and expand the locus 



Conservation 
Landmarks: 
Bureau of 
Biological 
Survey and 
National 
Biological 
Service 



by 

Milton Friend 
National Biological Service 



Introduction — Our Living Resources 



Investigation and research 

Study of life habits of wild animals 

Classification of wild animals 

Studies in geographic distribution of wild 
animals and plants 

Life zone investigations of definite areas 

Biological surveys of definite areas 

Special big game investigations 

Investigations for improvement of reindeer 
in Alaska 

Investigations at reindeer experiment station 

Investigations of problems of fur farmers 

Studies in fur animal disease and parasites 

Investigations of problems of rabbit raisers 

Studies of rabbit diseases, etc. 

Investigations in animal poisons 

Studies in bird migration 

Bird censuses (general) 

Wild fowl censuses 

Bird banding 

Food habits studies by laboratory examina- 
tions of stomach contents of birds, mam- 
mals, reptiles, and amphibians 

Studies in game bird propagation 

Specific studies in covert restocking 

Surveys of food resources for waterfowl 

Investigations and experiments in predatory 
animal control 

Investigations and experiments in control of 
injurious rodents 

Investigations and experiments in control of 
other animal pests 

Investigations and experiments in control of 
bird pests 



Activities of the Bureau 

of Biological Survey 

(Cameron 1929) 



Encouragement of useful forms of wildlife 

Advice on game bird and animal propaga- 
tion methods 

Devising of methods for attracting birds 
about parks, homes, etc. 

Encouragement of conservation of wild fur 
bearers 

Advice on small animal production (for pets 
and laboratory use) 

Maintenance and protection of game pre- 
serves and birds refuges 

Restocking of reservations 

Disposal of surplus animals on reservations 

Issuance of permits for fur farming on cer- 
tain Alaskan islands 

Administration of Upper Mississippi Wild 
Life and Fish Refuge Act 

Administration of act protecting wildlife on 
reservations 

Repression of undesirable forms of 
wildlife 

Killing of predatory animals 
Leadership and demonstration in coopera- 
tive effort against predatory animals 



Leadership and demonstration in coopera- 
tive effort against injurious rodents 

Leadership and demonstration in coopera- 
tive effort against other animal pests and 
injurious birds 

Processing of poisons and food stuffs for use 
against predatory and noxious animals 

Protection of wildlife 

Administration of Migratory Bird Treaty and 
Lacey acts by warden service and in coop- 
eration with state law enforcement agen- 
cies 

Issuance of permits for game propagation 

Regulation of importation of wild birds and 
animals 

Preparation of regulations under Alaska 
game law 

Dissemination of information 

Preparation and editing of publications 
Preparation of exhibits and photographs 
Answering of inquiries 
Addresses by officers (conventions, univer- 
sities, etc.) 

Miscellaneous 

Regulation of grazing of domestic stock in 
certain Alaskan islands 



from agriculture and horticulture to the new 
subject of forestry. At the same time, the work 
was moved from the Division of Entomology to 
the new Division of Economic Ornithology and 
Mammalogy. Dr. C. Hart Merriam became the 
first division chief in July 1886 (Cameron 
1929). 

The new division continued to study wildlife 
food habits, migration, and species distribution. 
It placed considerable emphasis on educating 
farmers about birds and animals affecting their 
interests so that destruction of useful species 
might be prevented. Dr. Merriam pursued the 
development of an extensive biological survey, 
advancing the argument that mapping of fauna] 
and floral areas would benefit farmers by iden- 
tifying the boundaries of areas fit for the growth 
of certain crops and those hospitable for certain 
breeds of livestock. In 1890, the appropriation 
language for the Department of Agriculture pro- 
vided for the investigation of "the geographic 
distribution of animals and plants," causing Dr. 
Merriam to note that "the division is now in 
effect a biological survey" (Cameron 1929:27). 

The major part of the division's 1891 activi- 
ties involved an extensive biological survey and 



biogeographic mapping of the Death Valley 
region of southern California and southern 
Nevada. This was followed by additional bio- 
logical surveys of various areas of the West. 
Biological surveys also were conducted beyond 
the continental borders of the United States into 
Alaska, Canada, and Mexico. In 1896 the 
Division of Ornithology and Mammalogy 
became the Division of Biological Survey 
(Cameron 1929). 

Food habit studies, which were continued 
along with the survey work, emphasized trans- 
mitting information to those who could benefit 
from it. Popular bulletins were prepared on bird 
migration, the economic impacts of specific 
wildlife species on agriculture, and the intro- 
duction of exotic species. In 1889, the division 
initiated the more scientific North American 
Fauna series, which included that year a gener- 
al paper discussing Dr. Merriam's concept of 
the life zones of North America (Cameron 
1929). 

The division was elevated to bureau status 
on July 1, 1905. During the next 34 years, activ- 
ities expanded to serve the growing U.S. con- 
servation movement. Diverse investigations and 



Our Living Resources Introdut tion 



research were carried out as well as technical 
assistance to the public and to game managers; 
animal damage control; regulatory functions 
including conservation law enforcement; 
administration of refuge lands; and public edu- 
cation through publications and exhibits {see 
box). Conservation problems included habitat 
loss, declining wildlife populations, species 
extinction, control of exotic species, control of 
predatory and injurious wildlife, pollution and 
disease control, and competition between 
wildlife, agriculture, and forestry. 

The BBS was transferred to the Department 
of Interior on July 1, 1939, and was made part 
of the U.S. Fish and Wildlife Service (USFWS). 
In November 1993, the biological research 
components within the Department of Interior, 
including those from the USFWS, the National 
Park Service, the Bureau of Land Manage- 
ment, the Bureau of Reclamation, and the 
Minerals Management Service were reorga- 
nized to form the National Biological Survey. 
The name was changed to the National 
Biological Service on January 5, 1995, to more 
accurately reflect the agency's mission. 

Then and Now 

Dr. Merriam noted that the chief work of the 
BBS was to obtain facts, for without a knowl- 
edge of facts there can be neither efficient 
administration nor intelligent regulation of 
wildlife to meet the needs of the nation 
(Cameron 1929). That same philosophy is 



inherent in Secretary of the Interior Bruce 
Babbitt's remarks about the NBS: 

The National Biological Survey will pro- 
duce the map we need to avoid the eco- 
nomic and environmental "train wrecks"" 
we see scattered across the country. NBS 
will provide the scientific knowledge 
America needs to balance the compatible 
goals of ecosystem protection and eco- 
nomic progress. . . . [The] National 
Biological Survey will unlock information 
about how we protect ecosystems and plan 
for the future. (National Research Council 
1993:181-182). 

Land management, regulatory, and law 
enforcement activities of the BBS remained 
with the USFWS and other parent bureaus with- 
in the Department of Interior when the NBS 
was formed. Only the biological research com- 
ponents of the department have become part of 
the NBS. This nonadvocacy biological science 
program will help the nation to resolve increas- 
ingly contentious and challenging issues in 
managing its biological resources. 

References 

Cameron, J. 1929. The Bureau of Biological Survey: us his- 
tory, activities, and organization. John Hopkins Press. 
New York. 339 pp. 

National Research Council (Committee on the Formation of 
the National Biological Survey). 1993. A biological sur- 
vey for the nation. National Academy Press. Washington. 
DC. 205 pp. 



For further information: 

Mi lion Friend 

National Biological Service 

National Wildlife Health Center 

6()()(i Schroedet Rd, 

Madison. Wl 53711 



*9ai&iBB2i ^*<CTS 




Distribution, 
Abundance, and Health 














Distribution, Abundance, and Health of 



Birds 

Mammals 

Reptiles and Amphibians 
Fishes 



PP9PH 



Plants 




>• 



•V 



■k. \ 



4- 
\ • 




< . 



Birds 



Overview 



Migratory bird popula- 
tions are an international 
resource for which there is special federal 
responsibility. Moreover, birds are valued and 
highly visible components of natural ecosys- 
tems that may be indicators of environmental 
quality. Consequently, many efforts have been 
directed toward measuring and monitoring the 
condition of North America's migratory bird 
fauna. The task is not an easy one because the 
more than 700 U.S. species of migratory birds 
are highly mobile and may occur in the United 
States during only part of their annual cycle. 
Some species annually make round-trip migra- 
tions spanning thousands of kilometers or 
miles, others engage in short or irregular migra- 
tions of tens or hundreds of kilometers, and 
even resident species are capable of moving 
great distances over short intervals. One often 
cannot tell whether a bird observed at a given 
moment is a resident, a migrant, a visitor from 
another locality, or the same individual seen 10 
minutes earlier. 

Determining status and trends is further 
complicated by the fact that each of these 
species has its own patterns of distribution and 
abundance, and each species has populations 
that respond to different combinations of envi- 
ronmental factors. Finally, the sheer abundance 
of birds estimated at 20 billion individuals in 



North America at its annual late-summer peak 
(Robbins et al. 1966) may make it difficult to 
obtain accurate counts of common species, and 
the absolute abundance of some may mask 
important changes in their status. 

Biologists have developed many different 
approaches to determining abundance and 
trends in abundance, and nearly all of the recog- 
nized census methods applicable to birds are 
represented by the articles in this section. Not 
surprisingly, trends among the large number of 
populations treated are mixed. 

Results from the nationwide Breeding Bird 
Survey (Peterjohn et al., this section) and a por- 
tion of the large-scale Christmas Bird Count 
(Root and McDaniel, this section) show that 
some populations are declining, others increas- 
ing, and many show what appears to be normal 
fluctuations around a more or less stable aver- 
age. Overall, approximately equal numbers of 
species appear to be increasing and decreasing 
over the past two to three decades. Groups of 
species with the most consistent declines are 
those characteristic of grassland habitats, appar- 
ently reflecting conversion of these habitats to 
other types of vegetative cover. 

Waterfowl populations are monitored close 
ly as a basis lor regulating annual harvests a! 
levels consistent with maintenance of popula- 
tions. Goose populations (Rusch el al.. 



Science Editor 

Russell J. Hall 
National Biological 

Service 

Division of Research 

Washington, DC 20240 



16 



Birds — Our Living Resources 



Hestbeck's "Canada Geese," Hupp et al., all this 
section) have shown some impressive gains 
over the past decades, but most gains have been 
registered by large-bodied geese, with several 
smaller species and smaller subspecies of the 
highly variable Canada goose (Branta canaden- 
sis) having depressed populations. 

Censusing and determining the status of nat- 
ural Canada goose populations are made more 
difficult by the widespread introduction and 
establishment of resident goose populations, 
which breed outside the traditional Arctic nest- 
ing areas and mix with migratory populations 
on the wintering grounds. 

Duck surveys address more than 30 species 
that might be legally hunted. Even though some 
species are stable or even increasing, many 
duck populations have declined in the past 
decade (Caithamer and Smith, this section). 
Biologists attribute these declines to losses of 
breeding and wintering habitats and a long peri- 
od of drought in breeding areas. Among species 
receiving special emphasis, canvasbacks 
(Aythya valisineria; Hohman et al., this section) 
showed a complex pattern with regional 
changes in distribution and abundance, and pin- 
tails (Anas acuta; Hestbeck's "Decline of 
Northern Pintails," this section) showed a wide- 
spread and nearly consistent pattern of decline. 

Results are preliminary, but two new census 
programs, the MAPS and BBIRD programs 
(Martin et al., this section), promise to provide 
much higher quality information on status and 
trends by measuring not only the presence of 
bird populations in breeding areas, but also their 
success. When fully operational, this approach 
may offer important clues regarding the causes 
of observed population changes. 

Shorebirds are highly migratory, and status 
and trends of their populations are largely deter- 
mined from observations made during periods 
in their life cycles in which birds congregate in 
limited breeding, staging, or migratory stopover 
areas. Populations of eastern (Harrington, this 
section) and western (Gill et al., this section) 
species show general patterns of decline, 
although some species, including those using 
inland areas, are too poorly studied to detect 
trends. Apparent dependence on critical breed- 
ing and staging areas suggests that populations 
of many species are vulnerable to habitat loss 
and disturbance. 

Seabirds in the Pacific region (Carter et al., 
Hatch and Piatt, both this section) include many 
diverse species that respond differently to fac- 
tors such as human proximity to nesting areas, 
oil spills, introduction of predators, depletion of 
fishery stocks, and availability of human refuse 
as food. Some species, including certain gulls, 
brown pelicans (Pelecanus occidentalis), and 
double-crested cormorants (Phalacrocorax 



auritus), have responded positively to recent 
changes in some areas, whereas others, includ- 
ing murrelets and murres (Family Alcidae) and 
kittiwakes (Genus Rissa), have shown declining 
trends. Populations of other species appear to 
fluctuate widely, and information for many 
species is insufficient to determine long-term 
trends. 

Colonial waterbirds of the continental and 
east coast regions of the United States (Erwin, 
this section) show trends related to many of the 
same factors operating in the Pacific region, 
with some species recovering from past losses 
from pesticides while some other species that 
exploit human refuse are increasing dramatical- 
ly. Populations of other species, especially cer- 
tain terns, are declining, probably as a result of 
habitat loss and degradation or other kinds of 
human disturbance. Special efforts have been 
made to determine status and trends of the pip- 
ing plover (Charadrius melodus; Haig and 
Plissner, this section), a species listed as endan- 
gered in certain parts of its range and as threat- 
ened in others. 

Populations of raptors (Fuller et al., this sec- 
tion) are difficult to census, but ospreys 
(Pandion haliaetus), bald eagles (Haliaeetus 
leucocephalus), and peregrine falcons (Falco 
peregrinus) have increased in numbers as they 
recover from past effects of pesticides. 
Populations of most vultures, hawks, and owls 
are either poorly known or believed to be stable. 
Notable exceptions are California condors 
(Gynmogyps californianus; Pattee and Mesta, 
this section), the crested caracara (Caracara 
plancus; Layne, this section), and spotted owls 
(Strix occidentalis), all of which enjoy or have 
been considered for additional protection. 
Mortality factors of eagles (Franson et al.. this 
section) have been monitored and, although 
these data do not directly measure population 
status, they do indicate trends in the kinds of 
factors that tend to depress population growth. 

The wild turkey {Meleagris gallopavo: 
Dickson, this section) has shown dramatic 
increases in distribution and abundance in 
recent decades because of translocations, habi- 
tat restoration, and harvest control. Mourning 
doves (Zenaida macrvura; Dolton, this section) 
have shown generally stable populations, 
although recent population declines in the west- 
ern states are disturbing. Regional increases of 
ravens (Corvus corax) in the southwest 
(Boarman and Berry, this section) are primarily 
of concern because of their potential effects as 
predators on eggs and young of the desert tor- 
toise (Gopherus agassizii). 

Populations of severely endangered species, 
like the California condor (Pattee and Mesta. 
this section), the Mississippi sandhill crane 
(Grus canadensis pulla; Gee and Hereford, this 



Our Living Resources Hmh 



17 



section), and the Puerto Rican parrot {Amazona 
vittata; Meyers, this section), are reasonably 
well known. Through censusing these species, 
biologists have tracked declines, often to a few 
individuals, and slow recoveries resulting from 
intensive management activities. Other rare 
species have populations that are depleted or 
vulnerable because of recent trends, but which 
can be censused with far less certainty. For 
example, willow flycatchers (Empidonax trail- 
lii; Sogge, this section) breed sparsely in parts 
of the Grand Canyon where exotic species have 
displaced natural riparian vegetation; likewise, 
the status of the red-cockaded woodpecker 
(Picoides borealis) appears closely tied to the 
decline of the longleaf pine (Pinus palustris) 
ecosystem (Costa and Walker, this section). 

Broad-scale programs such as the Breeding 
Bird Survey, annual waterfowl surveys, and 
wintering surveys such as the Christmas Bird 
Count may provide information on status and 
trends for as many as 75% of U.S. bird species, 
at least to the extent that they would provide 
evidence of catastrophic declines. Remaining 



species may be censused only with difficulty 
and often with imprecision because they are 
secretive, rare, highly mobile, or occupy poorly 
accessible areas. Specialized surveys provide 
information on sonic of these groups but. as 
indicated by the articles in this section, they do 
so with varying degrees of success. Much work 
remains to be done on obtaining better informa- 
tion and developing better ways of interpreting 
available information on difficult-to-census 
species. 

If any overall conclusion is possible on the 
wide array of information now available on sta- 
tus and trends of bird populations it is this: 
apparent stability for many species; increases in 
some species, many of which are generalists 
adaptable to altered habitats; and decreases in 
other species, many of which are specialists 
most vulnerable to habitat loss and degradation. 

Reference 

Robbins. C.S.. B. Bruun. and H.S. Zim. 1966. Birds of 
North America. Golden Press, New York. 340 pp. 



The North American Breeding Bird Survey 
(BBS) was begun in 1966 to collect stan- 
dardized data on bird populations along more 
than 3,400 survey routes across the continental 
United States and southern Canada. The BBS 
has been used to document distributions and 
establish continental, regional, and local popu- 
lation trends for more than 250 species. 

We summarize here survey-wide patterns in 
the 1966-92 population trend estimates for 245 
species of birds observed on a minimum of 40 
routes with a mean relative abundance of 1.0 
bird per route. Survey-wide trend estimates are 
also summarized for six groupings of birds, pro- 
viding insight into broad geographical patterns 
of population trends of North American birds. 

Methods 

The BBS routes are located along secondary 
roads and surveyed each year during the peak of 
the breeding season by observers competent in 
bird identification. Each route is 39.4 km (24.5 
mi) long, with 50 stops placed at 0.8-km (0.5- 
mi) intervals (Robbins et al. 1986). To estimate 
population change, we used a procedure called 
route regression, described in greater detail by 
Geissler and Sauer (1990). 

We examined population change in several 
ways. First, we estimated overall population 
change for individual species over the entire 
survey area. Second, we looked for temporal 
and geographic patterns in individual bird 
species (e.g., Sauer and Droege 1990). 

Additionally, we analyzed overall patterns of 



population change for several species of partic- 
ular management interest. Groups of birds were 
defined by migration status (nonmigratory, 
short-distance, and Neotropical migrants) or by 
breeding habitat (grassland, shrubland, or 
woodland; see also Peterjohn and Sauer 1993). 
For each group, we determined the percentage 
of species with positive (> 0) trends. If popula- 
tion change is not consistent within the group, 
about half (50%) of the species should show 
positive trends. Clearly, some species will show 
very significant declines (or increases) over the 
interval, and these species can be identified in 
the Appendix. However, the percentage of 
species with positive population trends is a con- 
venient summary of information from all 
species within the group to demonstrate overall 
trend patterns. 

Finally, to display regional patterns of popu- 
lation change, we calculated the mean trend for 
the species in each group for each survej route. 
We used an Arc/Info geographic information 
system to summarize and display geographic 
patterns of population change (Isaaks and 
Srivastava 1989; ESRI 1992). 

Trends 

Of the 245 species considered. 130 have 
negative trend estimates. 57 of which exhibit 
significant declines. Species with negative trend 
estimates are found in all families, bul the\ are 
especially prevalent among the mimids (mock- 
ingbirds and thrashers) and sparrows \ total Ol 
115 species exhibits positive trends. 44 ol 



Breeding Bird 

Survey: 

Population 

Trends 

1966-92 



by 

Bruce J. Peterjohn 

John R. Sauer 

Sandra Orsillo 

National Biological Service 



18 



Birds — Our Living Resources 



Fig. 1. Geographic patterns in the 
mean trends for grassland bird 
species during 1966-92. 

Table. Percentage of species with 
increasing populations for six 
groups of birds having shared life- 
history traits. The P value indi- 
cates the probability that the per- 
centage differs from 50%. 



which are significant increases. Flycatchers and 
warblers have the largest proportions of species 
with increasing populations. 

The percentage of increasing species within 
each group of species having shared life-history 
traits is summarized in the Table. The most con- 
sistent declines are by grassland birds; only 
18% have increasing population trends. These 
declines are most widespread in eastern North 
America, where few grassland species breed 
(Fig. 1). Declining populations are also preva- 
lent across the Great Plains, which includes the 
breeding ranges of most grassland birds. The 
pattern within western North America is mixed, 
except for regions of declines along the Pacific 
coast. 

A significant proportion of shrubland and 
old-field bird species also exhibits population 
declines (Table). As with grassland birds, 
regions with declines are most prevalent in east- 



Negative trends 
Positive trends 




Group 


No. of species in 
each group 


Increasing 
(%) 


P 


Breeding habitats 


Grassland 


17 


18 


0.01 


Shrubland 


58 


34 


0.02 


Woodland 


80 


59 


0.15 


Migration 


Short distance 


69 


42 


0.23 


Nonmigratory 


41 


41 


0.35 


Neotropical 


98 


50 


0.92 


All species 


237 


47 


0.36 



Negative trends 
Positive trends 



Fig. 2. Geographic patterns in the 
mean trends for shrubland and old- 
field bird species during 1966-92. 




ern North America as well as in the southern 
Great Plains from Kansas and Missouri south to 
Texas (Fig. 2). Shrubland species appear to be 
generally increasing in western North America. 
A majority of woodland bird populations is 
increasing across most of the continent (Fig. 3). 
Decreasing populations prevail in a few regions, 
such as along the Appalachians from West 
Virginia to northern Alabama, from Arkansas 
across central Texas, and along the Pacific coast 
from Oregon to central California. Woodland 
birds, however, are increasing in more areas 
than either grassland or early successional 
species. 



Negative trends 
Positive trends 




Fig. 3. Geographic patterns in the mean trends for wood- 
land bird species during 1966-92. 

Neotropical migrants have received consid- 
erable attention in recent years, yet as many 
species have increased as have decreased during 
1966-92 (Table). A region with apparently 
declining populations extends from the southern 
Great Plains across the southeastern states and 
along the Appalachian Mountains to southern 
New England (Fig. 4). Increasing mean popula- 
tions prevail across the northern Great Plains 
and throughout much of western North 
America. The pattern of population decline in 
the eastern United States noted by Robbins et 
al. (1989) occurred after 1978 and is not reflect- 
ed in these long-term trends. 

Short-distance migrants and permanent resi- 
dents have slightly greater percentages of 
decreasing species (Table). Both groups have 
negative mean trends in the southeastern states 
and from the lower Great Lakes into the 
Appalachian Mountains, but the patterns else- 
where are mixed (Figs. 5, 6). 

These results indicate that grassland .and 
shrubland birds are experiencing the most con- 
sistent and widespread declines of any group of 
species. Whenever possible, appropriate conser- 
vation measures should be undertaken to 
enhance the population trends of these species. 
While the BBS data indicate the population 



Our Living Resources Birds /'> 



Negative trends 
Positive trends 




Fig. 4. Geographic patterns in the mean trends for 
Neotropical migrant bird species during 1966-92. 

trends for breeding birds, these data are not 
designed to identify the factors responsible for 
these trends. To understand how bird popula- 
tions are responding to the changing habitat 
conditions in North America, additional studies 
are needed that would combine the BBS results 
with regional data on land-use changes, weath- 
er conditions, and other variables. 

References 

ESRI. 1992. Understanding GIS: the Arc/Info method. 
Environmental Systems Research Institute, Inc., 
Redlands, CA. 416 pp. 

Geissler, P.H., and J.R. Sauer. 1990. Topics in route-regres- 
sion analysis. Pages 53-56 in J.R. Sauer and S. Droege. 
eds. Survey designs and statistical methods for the esti- 
mation of avian population trends. U.S. Fish and Wildlife 
Service Biological Rep. 90(1). 

Isaaks, E.H., and R.M. Srivastava. 1989. An introduction to 
applied geostatistics. Oxford University Press, New 
York. 561 pp. 

Peterjohn, B.G., and J.R. Sauer. 1993. North American 
Breeding Bird Survey annual summary 1990-1991. Bird 
Populations 1:52-67. 



Species 


Scientific name 


Trend 


P* 

i 


No. of 
•outes 


American white pelican 


Pelecanus erythrorhynchos 


3.60 


0.00 


152 


Great egret 


Casmerodius albus 


1.5 


ns 


513 


Little blue heron 


Egretla caerulea 


-1.45 


ns 


429 


Cattle egret 


Bubulcus ibis 


2.09 


ns 


475 


White ibis 


Eudocimus albus 


3.17 


ns 


173 


White-faced ibis 


Plegadis chihi 


32.27 


0.01 


61 


Canada goose 


Branta canadensis 


7.05 


0.00 


1,090 


Mottled duck 


Anas lulvigula 


-5.27 


0.03 


64 


Mallard 


A. platyrhynchos 


0.98 


ns 


1,890 


Northern pintail 


A. acuta 


-5.65 


0.00 


502 


Blue-winged teal 


A. discors 


-0.92 


ns 


814 


Northern shoveler 


A. clypeata 


0.18 


ns 


379 


Gadwall 


A. strepera 


376 


0.00 


389 


Lesser scaup 


Aythya affinis 


2.08 


ns 


263 


Red-breasted merganser 


Mergus senator 


-9.57 


0.02 


53 


Black vulture 


Coragyps atratus 


1.72 


ns 


540 


Turkey vulture 


Cathartes aura 


0.37 


ns 


1,691 


Ring-necked pheasant 


Phasianus colchicus 


-1.24 


0.10 


1.263 


Northern bobwhite 


Colinus virginianus 


-2.43 


0.00 


1.338 


Scaled quail 


Callipepla squamata 


-3.31 


0.00 
ns 


104 


Gambel's quail 


C. gambelii 


0.90 


82 


California quail 


C. calitornica 


-0.04 


ns 


264 


Mountain quail 


Oreortyx pictus 


1.37 


ns 


112 


American coot 


Fulica americana 


-0.51 


ns 


620 



Negative trends 
s Positive trends 




Robbins, C.S., D. Bystrak, and PH. Geissler. 1986. The 
Breeding Bird Survey: its first fifteen years, 1965-1979. 
U.S. Fish and Wildlife Service Resour. Publ. 157. 196 pp. 

Robbins, C.S., J.R. Sauer, R.S. Greenberg, and S. Droege. 
1989. Population declines in North American birds that 
migrate to the Neotropics. Proceedings of the National 
Academy of Science USA 86:7658-7662. 

Sauer, J.R., and S. Droege. 1990. Recent population trends 
of the eastern bluebird. Wilson Bull. 102:239-252. 



Species 



Scientific name 



Trend P 



, No. of 
routes 



Sandhill crane 
Killdeer 

Black-necked stilt 
Willet 

Upland sandpiper 
Long-billed curlew 
Marbled godwit 
Common snipe 
Laughing gull 
Franklin's gull 
Ring-billed gull 
California gull 
Herring gull 
Glaucous-winged gull 
Great black-backed gull 
Black tern 
Rock dove 
Band-tailed pigeon 
White-winged dove 
Mourning dove 
Common ground dove 
Yellow-billed cuckoo 
Lesser nighthawk 
Common nighthawk 



Grus canadensis 4.30 

Charadrius vocilerus -0.38 

Himantopus mexicanus 0.63 

Catoptrophorus semipalmatus -0.72 



0.00 259 
ns 2,692 
ns 119 



Bartramia longicauda 
Numenius americanus 
Limosa tedoa 
Gallinago gallinago 
Larus atncilla 
L pipixcan 
L delawarensis 
L. calitornicus 
L argentatus 
L glaucescens 
L mannus 
Chlidonias niger 
Cotumba Ima 
C. tasciata 
Zenaida asiatica 
Z macroura 
Columbma passerina 
Coccyzus americanus 
Chordeiles acutipennis 
C minor 



3.28 
-1.61 

071 

0.14 

6.01 
-5.95 

7 43 
•1.27 
-206 

3.85 
-1.47 
-4.51 

1 04 
-369 

003 

0.02 
-3.13 
•130 

5.08 
-0 34 



ns 

0.00 

ns 

ns 



295 
687 
234 
188 



ns 1,011 
000 125 



ns 
002 



231 
684 



ns 230 
009 474 



0.09 

ns 
0.00 



40 

125 
368 



006 2.255 

0.00 189 

ns 78 

ns 2,726 

001 194 

000 1,637 

03 118 

ns 1.609 



Fig. 5. Geographic patterns in the 

mean [rends for short-distance 
migrant bird species during 1966- 
92. 



Fig. 6. Geographic patterns in the 

mean trends for permanent resi 
dent bird species during 1966-92, 



Appendix. Population trends ol 
birds from the North American 
Breeding Bird Survey, Tb appeal 
in this list, the species must have 
been seen on > 40 routes al an 
average count of > 1 bird/route 
We present trends (%/yeai I. proba 
bility i /'i. and the nurnbei ol 
routes on which the species was 
seen See Peterjohn and Sauei 
1993 lor group classification 



20 



Birds — Our Living Resources 



Species 

Chuck-will's-widow 


Scientific name 

Caprimulgus carolinensis 


Trend 

-0.78 


p. No. of 
routes 

ns 522 


Species 

Blue-gray gnatcatcher 


Scientific name 

Polioptila caerulea 


Trend 

1.03 


p. No. of 
routes 

ns 1,233 


Black swift 


Cypseloides niger 


1.61 


ns 


79 


Black-tailed gnatcatcher 


P. melanura 


-0.22 


ns 


57 


Chimney swift 


Chaetura pelagica 


-0.84 


0.08 


1,789 


Eastern bluebird 


Sialia sialis 


2.52 


0.00 


1,633 


White-throated swift 


Aeronautes saxatalis 


-3.38 


ns 


139 


Mountain bluebird 


S. currucoides 


0.56 


ns 


422 


Broad-tailed hummingbird 


Selasphorus platycercus 


0.42 


ns 


115 


Veery 


Catharus fuscescens 


-1.06 


0.06 


964 


Rufous hummingbird 


S. rulus 


-3.38 


0.00 


188 


Gray-cheeked thrush 


C. minimus 


-4.46 


ns 


43 


Red-headed woodpecker 


Melanerpes erythrocephalus 


-1.84 


0.00 


1,236 


Swainson's thrush 


C. ustulatus 


0.00 


ns 


707 


Acorn woodpecker 


M. formicivorus 


0.98 


ns 


138 


Hermit thrush 


C. guttatus 


2.10 


0.01 


912 


Golden-fronted woodpeckerW. aurifrons 


-1.86 


ns 


56 


Wood thrush 


Hylocichla mustelina 


-1.88 


0.00 


1,510 


Red-bellied woodpecker 


M. carolinus 


0.59 


ns 


1,246 


American robin 


Turdus migratorius 


1.03 


0.01 


2,588 


Yellow-bellied sapsucker 


Sphyrapicus varius 


-0.85 


ns 


605 


Varied thrush 


Ixoreus naevius 


2.16 


0.06 


148 


Nutlall's woodpecker 


Picoides nuttallii 


1.44 


ns 


95 


Wrentit 


Chamaea lasciata 


-1.39 


ns 


113 


Downy woodpecker 


P. pubescens 


0.14 


ns 


2,214 


Gray catbird 


Dumetella carolinensis 


-0.42 


ns 


1,941 


Yellow-shafted flicker 


Colaptes auratus 


-2.75 


0.00 


2,062 


Northern mockingbird 


Mimus polyglottos 


-0.98 


0,03 


1,694 


Red-shafted flicker 


C. cafer 


-0.87 


ns 


689 


Sage thrasher 


Oreoscoptes montanus 


1.16 


ns 


244 


Olive-sided flycatcher 


Contopus borealis 


-2.52 


0.00 


736 


Brown thrasher 


Toxostoma rufum 


-1.19 


0.01 


1,917 


Western wood-pewee 


C. sordidulus 


-0.39 


ns 


637 


Curve-billed thrasher 


T. curvirostre 


-3.59 


0.00 


100 


Eastern wood-pewee 


C. virens 


-1.64 


0.00 


1,719 


California thrasher 


T. redivivum 


-4 06 


0.05 


83 


Yellow-bellied flycatcher 


Empidonax flaviventris 


3.58 


0.01 


263 


Sprague's pipit 


Anthus spragueii 


-3.52 


0.02 


140 


Acadian flycatcher 


E. virescens 


0.50 


ns 


854 


Cedar waxwing 


Bombycilla cedrorum 


2.36 


0.00 


1627 


Alder flycatcher 


E. alnorum 


1.30 


0.04 


788 


Phainopepla 


Phainopepla nitens 


2.53 


0.05 


104 


Willow flycatcher 


E. traillii 


-0.62 


ns 


1,152 


Loggerhead shrike 


Lanius ludovicianus 


-3.20 


0.00 


1364 


Least flycatcher 


E. minimus 


-0.55 


ns 


1,150 


European starling 


Sturnus vulgaris 


-0.99 


0.02 


2727 


Hammond's flycatcher 


E. hammondii 


1.50 


ns 


221 


White-eyed vireo 


Vireo griseus 


-0.15 


ns 


945 


Dusky flycatcher 


E. oberholseri 


0.72 


ns 


265 


Solitary vireo 


V. solitarius 


3.28 


0.00 


954 


Pacific-slope flycatcher 


E. difficilis 


1.47 


ns 


218 


Warbling vireo 


V. gilvus 


1.31 


0,01 


1740 


Eastern phoebe 


Sayornis phoebe 


0.64 


ns 


1,650 


Philadelphia vireo 


V. philadelphicus 


1.50 


ns 


191 


Ash-throated flycatcher 


Myiarchus cinerascens 


2.38 


0.01 


370 


Red-eyed vireo 


V. olivaceus 


1.39 


0.01 


2020 


Great crested flycatcher 


M. crinitus 


0.03 


ns 


1,804 


Tennessee warbler 


Vermivora peregrina 


4.21 


ns 


341 


Brown-crested flycatcher 


M. tyrannulus 


6.15 


0.00 


47 


Orange-crowned warbler 


V. celata 


-0.71 


ns 


346 


Cassin's kingbird 


Tyrannus vociferans 


-1.74 


ns 


138 


Nashville warbler 


V. ruficapilla 


1.35 


ns 


673 


Western kingbird 


T. verticalis 


1.51 


0.01 


942 


Northern parula 


Parula americana 


0.82 


ns 


970 


Eastern kingbird 


T. tyrannus 


-0.10 


ns 


2,267 


Yellow warbler 


Dendroica petechia 


0.94 


0.05 


2161 


Scissor-tailed flycatcher 


T. Micatus 


-0.08 


ns 


244 


Chestnut-sided warbler 


D. pensylvanica 


-0.60 


ns 


788 


Horned lark 


Eremophila alpestris 


-0.65 


ns 


1,750 


Magnolia warbler 


D. magnolia 


2.80 


0.00 


527 


Purple martin 


Progne subis 


0.71 


ns 


1,623 


Cape May warbler 


D. tigrina 


2.95 


ns 


239 


Tree swallow 


Tachycineta bicolor 


1.27 


0.04 


1,707 


Myrtle warbler 


D. coronata 


1.41 


0.09 


575 


Violet-green swallow 


T. thalassina 


0.76 


ns 


511 


Audubon's warbler 


D.c. auduboni 


0.08 


ns 


386 


Northern rough-winged 


Stelgidopteryx serripennis 


0.95 


ns 


2,119 


Black-throated gray warbler 


D. nigrescens 


2.32 


0.07 


190 


swallow 


Townsend's warbler 


D. townsendi 


1.63 


ns 


145 


Bank swallow 


Riparia riparia 


-0.48 


ns 


1,318 


Hermit warbler 


D. occidentalis 


0.79 


ns 


82 


Cliff swallow 


Hirundo pyrrhonota 


0.98 


ns 


1,737 


Black-throated green warblei 


D. virens 


-0.45 


ns 


637 


Barn swallow 


H. rustica 


0.37 


ns 


2,701 


Blackburnian warbler 


D. fusca 


0.87 


ns 


511 


Gray jay 


Perisoreus canadensis 


-1.28 


ns 


350 


Pine warbler 


D. pinus 


2.12 


0.00 


797 


Steller's jay 


Cyanocitta stelleri 


0.39 


ns 


328 


Prairie warbler 


D. discolor 


-2.15 


0.00 


773 


Blue jay 


C. cristata 


-1.81 


0.00 


1,986 


Bay-breasted warbler 


D. castanea 


-0.04 


ns 


216 


Scrub jay 


Aphelocoma coerulescens 


1.27 


0.04 


272 


Blackpoll warbler 


D. striata 


-0.33 


ns 


178 


Pinyon jay 


Gymnorhinus cyanocephalus 


-1.65 


ns 


132 


Black-and-white warbler 


Mniotilta varia 


0.91 


ns 


1126 


Black-billed magpie 


Pica pica 


-1.34 


0.05 


577 


American redstart 


Setophaga ruticilla 


-0.58 


ns 


1299 


American crow 


Corvus brachyrhynchos 


0.85 


0.06 


2,578 


Ovenbird 


Seiurus aurocapillus 


0.55 


ns 


1278 


Fish crow 


C. ossilragus 


2.93 


0.01 


466 


Northern waterlhrush 


S. noveboracensis 


0.49 


ns 


615 


Chihuahuan raven 


C. cryptoleucus 


-2.48 


ns 


87 


Kentucky warbler 


Oporornis lormosus 


-0.77 


ns 


685 


Common raven 


C. corax 


3.66 


0.00 


1,202 


Mourning warbler 


O. Philadelphia 


0.15 


ns 


538 


Black-capped chickadee 


Parus atricapillus 


1.89 


0.00 


1,433 


MacGillivray's warbler 


O. tolmiei 


-0.58 


ns 


309 


Carolina chickadee 


P. carolinensis 


-0.67 


ns 


862 


Common yellowthroat 


Geothlypis trichas 


-0.48 


ns 


2361 


Mountain chickadee 


P. gambeli 


0.07 


ns 


291 


Hooded warbler 


Wilsonia citrina 


1.49 


ns 


608 


Chestnut-backed chickadee/ 3 rufescens 


-1.54 


ns 


133 


Wilson's warbler 


W. pusilla 


0.53 


ns 


525 


Plain titmouse 


P. mornalus 


-2.30 


0.01 


180 


Canada warbler 


W. canadensis 


-0,73 


ns 


504 


Tufted titmouse 


P. bicolor 


0.64 


ns 


1.289 


Yellow-breasted chat 


Icteria virens 


-0,43 


ns 


1273 


Black-crested titmouse 


P.b. atricrislatus 


2.06 


0.03 


64 


Summer tanager 


Piranga rubra 


-0.19 


ns 


761 


Verdin 


Aunparus flavicep 


-1.38 


ns 


97 


Scarlet tanager 


P. olivacea 


0.22 


ns 


1257 


Bushtit 


Psallriparus minimus 


-1.13 


ns 


250 


Western tanager 


P. ludoviciana 


-0.31 


ns 


472 


Red-breasted nuthatch 


Sitta canadensis 


2.48 


0.00 


872 


Northern cardinal 


Cardinalis cardmalis 


-0.21 


ns 


1591 


Brown-headed nuthatch 


S. pusilla 


-1.30 


ns 


290 


Pyrrhuloxia 


C. sinuatus 


-0.73 


ns 


61 


Cactus wren 


Campylorhynchus 
brunneicapillus 


-0.89 


ns 


136 


Rose-breasted grosbeak 


Pheucticus ludovicianus 


-0.19 


ns 


1146 


Black-headed grosbeak 


P. melanocephalus 


-0.32 


ns 


509 


Rock wren 


Salpinctes obsolelus 


-1.68 


0.04 


509 


Blue grosbeak 


Guiraca caerulea 


1.86 


0.00 


1014 


Carolina wren 


Thryolhorus ludovicianus 


1.01 


0.03 


1,118 


Lazuli bunting 


Passerina amoena 


0.14 


ns 


417 


Bewick's wren 


Thryomanes bewickii 


-0.35 


ns 


594 


Indigo bunting 


P. cyanea 


-0.57 


ns 


1725 


House wren 


Troglodytes aedon 


1.55 


0.00 


1,924 


Painted bunting 


P. ciris 


-3.21 


0.00 


269 


Winter wren 


T. troglodytes 


2.25 


ns 


659 


Dickcissel 


Spiza americana 


-1.58 


0.02 


791 


Golden-crowned kinglet 


Regulus satrapa 


-0.01 


ns 


541 


Green-tailed towhee 


Pipilo chlorurus 


0.41 


ns 


212 


Ruby-crowned kinglet 


R. calendula 


■1.31 


ns 


656 


Rufous-sided towhee 


P. erythrophthalmus 


-1.99 


0.00 


1951 



Our Living Resources Hmh 



21 



Species 


Scientific name 


Trend 


p. No. of 
routes 


California towhee 


P. califormcus 


-0.22 


ns 


113 


Brown towhee 


P. luscus 


-2.67 


0.00 


83 


Cassin's sparrow 


Aimophila cassinii 


-2.85 


0.00 


171 


Chipping sparrow 


Spizella passerina 


-0.04 


ns 


2,300 


Clay-colored sparrow 


S. pallida 


-1.31 


0.02 


444 


Brewer's sparrow 


S. brewer! 


-3.68 


0.00 


376 


Field sparrow 


S. pusilla 


-3.25 


0.00 


1,581 


Vesper sparrow 


°ooecetes gramineus 


-0.25 


ns 


1,488 


Lark sparrow 


Chondestes grammacus 


-3.42 


0.00 


935 


Black-throated sparrow 


Amphispiza bilineata 


-3.78 


0.02 


225 


Sage sparrow 


A. belli 


-2.43 


ns 


210 


Lark bunting 


Calamospiza melanocorys 


-2.86 


0.03 


359 


Savannah sparrow 


Passerculus sandwichensis 


-0.57 


ns 


1,461 


Baird's sparrow 


Ammodramus bairdii 


-1.52 


ns 


134 


Grasshopper sparrow 


A. savannarum 


-4.48 


0.00 


1,479 


Fox sparrow 


Passerella iliaca 


0.44 


ns 


224 


Song sparrow 


Melospiza melodia 


-0.80 


0.09 


2,079 


Lincoln's sparrow 


M. lincolnii 


3.99 


0.02 


420 


Swamp sparrow 


M. georgiana 


0.50 


ns 


783 


White-throated sparrow 


Zonotrichia albicollis 


-1.44 


0.01 


635 


White-crowned sparrow 


Z. leucophrys 


-1.91 


0.01 


274 


Slate-colored junco 


Junco hyemalls 


-0.47 


ns 


545 


Oregon junco 


J.h. oregonus 


-1.23 


0.08 


341 


Gray-headed junco 


J.h. caniceps 


2.04 


ns 


50 


McCown's longspur 


Calcarius mccownii 


8.32 


0.00 


68 


Chestnut-collared longspur 


C. omatus 


0.62 


ns 


153 


Bobolink 


Dollchonyx oryzivorus 


-1.33 


0.01 


1,147 



Species 


Scientific name 


Trend 


l 


Moot 
outes 


Red-winged blackbird 


Agelaius phoeniceus 


-1.06 


01 


2,760 


Tricolored blackbird 


A. tricolor 


4.83 


ns 


69 


Eastern meadowlark 


Sturnella magna 


•2.18 


0.00 


1,742 


Western meadowlark 


S. neglecta 


-0.56 


ns 


1,334 


Yellow-headed blackbird 


Xanthocephalus 
xanthocephalus 


1.53 


ns 


649 


Brewer's blackbird 


Euphagus cyanocephalus 


-1.15 


0.06 


1,006 


Great-tailed grackle 


Quiscalus mexicanus 


7.40 


0.00 


198 


Boat-tailed grackle 


O. major 


2.52 


0.05 


118 


Common grackle 


Q. quiscula 


•1.44 


0.00 


2,196 


Bronzed cowbird 


Moloihrus aeneus 


-1.12 


ns 


55 


Brown-headed cowbird 


M. ater 


-0.88 


0.06 


2,780 


Orchard oriole 


Icterus spurius 


-1.38 


0.03 


1,313 


Baltimore oriole 


1. galbula 


0.26 


ns 


1,594 


Bullock's oriole 


l.g. bullockii 


-0.81 


ns 


614 


Scott's oriole 


1. parisorum 


2.26 


ns 


113 


Pine grosbeak 


Pmicol? enucleator 


6.36 


0.01 


152 


Purple finch 


Carpodacus purpureus 


-1.19 


0.05 


921 


Cassin's finch 


C. cassinii 


1.27 


ns 


235 


House finch 


C. mexicanus 


-0.14 


ns 


1,420 


Red crossbill 


Loxia curvirostra 


2.13 


ns 


438 


White-winged crossbill 


L. leucoptera 


-5.52 


0.09 


155 


Pine siskin 


Carduelis pinus 


0.38 


ns 


778 


Lesser goldfinch 


C. psaltna 


•1.22 


ns 


281 


American goldfinch 


C. tristis 


-1.06 


0.03 


2,165 


Evening grosbeak 


Coccothraustes vespertmus 


-0.37 


ns 


596 


House sparrow 


Passer domesticus 


-1.65 


0.00 


2,557 



"ns-not significant. 



For further information: 

Bruce G. Peterjohn 

National Biological Service 

Patuxent Environmental Science 

Center 

Laurel. MD 20708 



Many studies have found significant 
changes, primarily declines, in popula- 
tions of breeding birds throughout the United 
States. Most studies have focused on birds that 
migrate to the Neotropics for winter. 
Speculations about causes of observed declines 
have primarily implicated habitat fragmentation 
and loss (e.g., deforestation) in Central and 
South America. The National Audubon 
Society's Christmas Bird Counts (CBC), begun 
in the winter of 1900-01, provide the data need- 
ed to discern consistent population trends in 
birds wintering throughout the United States. 

For this study we used the CBC data to 
examine population trends of songbirds with 
ranges that apparently are limited by lower tem- 
peratures in the North. We chose these species 
to track populations of birds that could be in 
peril in the future. These birds potentially will 
be more quickly affected by changing climate 
than other birds, and we need baseline informa- 
tion on them to document possible conse- 
quences of global climatic change. The species 
that are indeed declining need to be monitored 
because the possible synergistic effects of 
declining populations and changing climate 
could result in local and even regional extinc- 
tions. 

Methods 

We examined 30 years of CBC data (winters 
of 1959-60 to 1988-89) for 50 songbirds whose 
northern range edges are associated with 



January minimum temperatures (Root 1988b). 
For each songbird species or subspecies at each 
count site, we calculated the number of individ- 
uals seen per counting effort (e.g., hours of 
observation). Yearly averages for each of the 
conterminous states were determined from 
these values for each species. Data were used 
from all count sites that were censused at least 
25 of the 30 years. For details on the method we 
used to calculate population trends, see Geissler 
and Noon (1981) and contact us. All of our con- 
clusions rest on very conservative analyses. 

Trends 

Of the 50 songbirds examined, 27 (54%) 
exhibited a statistically and biologically signifi- 
cant trend in at least one state (Fig. 1 ). Of these 
27 species, 16 (599$ ) had populations declining 
in more states than states in which they were 
increasing; 12 exhibited only declines and 4 had 
a population increase in at least one state. Ten 
(37%) of the 27 species had populations 
increasing in more states than states exhibiting 
declines, with 7 exhibiting only population 
increases. One (4%) species had populations 
increasing and decreasing in the same Dumber 
of states. 

In general, the populations of birds that cat 
seeds from grasses and forbs (e.g.. sparrows and 
meadowlarks) seem to be declining more fre- 
quently than those oi birds that eat seeds from 
shrubs and trees, or hen ies (e.g.. tufted titmouse 
[Parus bicolor] and cedar waxwing [Bombycilla 



Winter 
Population 
Trends of 
Selected 
Songbirds 



by 

Terry L. Root 

I 'niversity of Michigan 

iMrry Mc Daniel 

National Center for 

A tmospheric Research 



22 



Birds — Our Living Resources 



15 



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Fig. 1. Number of states with population trends either declining or increasing for 27 songbirds. 



cedrorum]) (Fig. 1 ). This situation may be due to 
the fact that the grassland and early succession- 
al habitats are being modified, while ornamental 
fruiting bushes, shrubs, and trees planted in 
urbanized areas may be benefiting the increasing 
species (Beddall 1963). The explanation, how- 
ever, is certainly more complex than this, given 
that some birds do not fit the pattern. For exam- 
ple, the American pipit (Anthus rubescens), 
which eats berries, crustaceans, and mollusks 
(Ehrlich et al. 1988), is decreasing in four states 
and increasing in none (Fig. 1 ). 

To evaluate the areas of the conterminous 
states showing increases or decreases in their 
bird populations, we counted the number of 
species showing a population change in each 
state and then calculated the percentage with 
respect to the number of the 27 species occur- 
ring in each state (Fig. 2). A total of 24 (50%) of 
the states has greater than 5% of these wintering 
bird species showing positive population trends, 
while 32 (67%) show declines of similar magni- 
tudes. 

Mapping the percentages (Fig. 3) indicates 
that the largest increase is in South Carolina, 
with the far western states, those in the north- 
central region, and a scattering of states in the 
eastern portion of the conterminous states show- 
ing positive population trends. 

The largest decreases (Fig. 3) are in South 
Carolina, Georgia, Florida. Alabama. Louisiana, 
and Delaware. The Pacific states, those in the 




Fig. 2. Number and percentage of 27 birds showing declining and increasing population trends, 



Our Living Resoun es Birds 



21 




Great Plains, and the southeastern portion of the 
conterminous states generally show the greatest 
declines, though the actual reasons for these 
population changes will need to be examined in 
more detail. Certainly, the pattern of extensive 
declines in most of the southern coastal states is 
quite alarming. 

Additionally, regions of the country that 
could be particularly influenced by global cli- 
matic change are the southern coasts (because 
of increased storms and degradation of coastal 
wetlands; IPCC 1990), and the Great Plains 
(owing to a significant decline in soil moisture; 
Leatherman 1992). Hence, the populations of 
birds in these areas need to be closely moni- 
tored to ensure preservation actions are taken 
before the combined effects of population 
declines and climate change result in extinc- 
tions. More studies and monitoring are warrant- 
ed to understand the possible consequences of 
these patterns. 

The analyses presented here can also be used 
to investigate population trends of target species 
across the country. Compare, for instance, the 
trends by state for the American tree sparrow 
(Spizella arborea: one of the most declining 
birds examined) and the cedar waxwing (one of 
the most increasing birds) with maps of their 
winter range and abundance patterns (Root 
1988a). This comparison reveals that significant 



population trends, whether positive or negative, 
seem to occur primarily along these species' 
northern range boundaries and in many coastal 
states. Such analyses could help target specific 
regions of the country where population trends 
of key (e.g., threatened) species need watching. 

References 

Beddall. B.G. 1963. Range expansions of the cardinal and 
other birds in the northeastern states. Wilson Bull. 
75:140-158. 

Ehrlich, P.R.. D.S. Dobkin. and D. Wheye. 1988. The bird- 
er's handbook. Simon and Schuster, New York. 785 pp. 

Geissler, P.H.. and B.R. Noon. 1981. Estimates of avian 
population trends from the North America Breeding Bird 
Survey. Pages 42-51 in C.J. Ralph and J.M. Scott, eds. 
Estimating the numbers of terrestrial birds. Studies in 
Avian Biology 6. 

IPCC. 1990. Climate change: the IPCC scientific assess- 
ment, (also see Climate change 1992: the supplementary 
report to the IPCC scientific assessment.) Intergovern- 
mental Panel on Climate Change. Cambridge University 
Press, New York, NY. 364 pp. 

Leatherman. S.P. 1992. Sea level rise: implications and 
responses. Pages 256-263 in S.K. Majumdar. L.S. 
Kalkstein, B. Yarnal, E.W. Miller, and L.M. Rosenfeld, 
eds. Global climate change: implications, challenges and 
mitigation measures. Pennsylvania Academy of Science. 
Phillipsburg, NJ. 

Root, T.L. 1988a. Atlas of wintering North American birds. 
University of Chicago Press. IL. 312 pp. 

Root, T.L. 1988b. Environmental factors associated with 
avian distributional boundaries. Journal of Biogeograph) 
15:489-505. 



Kij>. 3. Percentage of 27 birds 
showing positive and negative 
I ivnds. 



For further information: 

Terry L. Root 

University of Michigan 

School of Natural Resources and 

Environment 

430 E. University 

Ann Arbor, MI 48109 



Populations of many North American land- 
birds, including forest-inhabiting species 
that winter in the Neotropics, seem to be declin- 
ing (Robbins et al. 1989; Terborgh 1989). These 
declines have been identified through 
broad-scale, long-term survey programs that 
identify changes in abundance of species, but 
provide little information about causes of 
changes in abundance or the health of specific- 
populations in different geographic locations. 

Population health is a measure of a popula- 
tion's ability to sustain itself over time as deter- 
mined by the balance between birth and death 



rates. Indices of population size do not always 
provide an accurate measure of population 
health because population size can be main- 
tained in unhealthy populations by immigration 
of recruits from healthy populations (Pulliam 
1988). Poor population health across many pop- 
ulations in a species eventually results in the 
decline of that species. Early detection of popu- 
lation declines allows managers to correct prob- 
lems before they are critical and u idespread. 

Demographic data (breeding productivity 
and adult survival) provide the kind of early 
warning signal that allows detection of 



Breeding 
Productivity 
and Adult 
Survival in 
Nongame 
Birds 



24 



Birds — Our Living Resources 



by 

Thomas E. Martin 
National Biological Service 

David F. DeSante 

The Institute for Bird 

Populations 

Charles R. Paine 

Montana Cooperative Wildlife 

Research Unit 

Therese Donovan 
University of Montana 

Randall Dettmers 

Ohio Cooperative Research 

Unit 

James Manolis 
Minnesota Cooperative Fish 
and Wildlife Research Unit 

Kenneth Burton 

The Institute for Bird 

Populations 



unhealthy populations in terms of productivity 
or survival problems (Martin and Guepel 1993). 
In addition, demographic data can help deter- 
mine whether population declines are the result 
of low breeding productivity or low survival in 
migration or winter. Breeding productivity data 
also can help identify habitat conditions associ- 
ated with successful and failed breeding 
attempts. Such information is critical for devel- 
oping habitat- and land-management practices 
that will maintain healthy bird populations 
(Martin 1992). Here, we provide examples of 
the kinds of information that can be obtained by 
broad-scale demographic studies. 

Demographic Programs 

The Monitoring Avian Productivity and 
Survivorship (MAPS) and Breeding Biology 
Research and Monitoring Database (BBIRD) 
programs were developed to gather the demo- 
graphic data needed to provide early and locali- 
ty-specific warning signals of population prob- 
lems. MAPS uses large, stationary mistnets to 
capture and examine young and adult birds for 
between-year changes and to determine 
long-term trends in adult population size, pro- 
ductivity, and adult survival. BBIRD locates 
and monitors bird nests to study changes in 
nesting success, determine causes of nesting 
failure (e.g., weather, habitat, nest predation, or 
nest parasitism), and identify habitat conditions 
associated with successful reproduction. 
Though both programs are new, they are grow- 
ing rapidly. We present example data to demon- 
strate initial results and burgeoning potential of 
these programs for the future. 

MAPS 

Initiated in 1989 and coordinated by The 
Institute for Bird Populations, MAPS is a coop- 
erative effort among federal and state agencies, 
private organizations, and bird banders to oper- 
ate a standardized continent-wide network of 
mist-netting and banding stations during the 
breeding season (DeSante 1992; DeSante et al. 
1993a, 1993b). A typical MAPS station 
involves about ten 12-m (39-ft) mistnets over a 
20-ha (49-acre) area. All birds captured 
throughout the breeding season are identified to 
species, age, and sex, and are banded with U.S. 
Fish and Wildlife Service bands. 

As of 1992, 170 stations were in operation 
and more than 94.000 captures of more than 
200 bird species were recorded. The number of 
adult birds captured is used as an index of adult 
population size while the proportion of young 
provides an index of postfledgling productivity 
(Baillie et al. 1993). 



BBIRD 

The BBIRD program, initiated in 1992, pro- 
vides detailed information on nesting productiv- 
ity and habitat needs of nongame birds at a 
national scale. BBIRD is a cooperative effort 
among biologists studying nesting productivity 
at local sites across the country. Participants fol- 
low a standard field protocol to obtain raw data 
on nesting productivity, causes of reproductive 
failure, vegetation measures at several spatial 
scales, and point counts (bird counts). Data 
from each local site are overseen by individual 
independent investigators who can obtain com- 
parative information from other sites. In addi- 
tion, overview analyses to identify national and 
regional trends are conducted at the Montana 
Cooperative Wildlife Research Unit. 

BBIRD study sites are in large forested 
blocks to minimize fragmentation effects and 
provide baseline information on productivity in 
undisturbed habitats as well as in auxiliary sites 
that have no habitat restrictions (e.g., grazed, 
fragmented, or logged sites). The BBIRD pro- 
gram now includes 23 sites in 17 states. Over 
8,000 nests of more than 150 bird species were 
monitored during the first 2 years of the pro- 
gram. 

Variation in Productivity 

The data provided by MAPS and BBIRD 
suggest that weather may be an important influ- 
ence on population dynamics at large and even 
continental scales. Prior data from 
constant-effort mist-netting in scrub habitat on 
the west coast have suggested that avian pro- 
ductivity may peak during average weather con- 
ditions and may be depressed when weather 
conditions deviate from average (DeSante and 
Geupel 1987). These facts are especially impor- 
tant because one of the most important ecologi- 
cal results of global climate change may be a 
greater annual variability in both local and 
large-scale weather conditions. 

Changes in indices of adult population size 
and postfledging productivity from the first 4 
years of MAPS are presented for all species 
pooled and for each target species caught at 10 
or more stations in 1992 in the Northeast and 
Northwest regions. These data indicate that pro- 
ductivity varied greatly from year to year, pre- 
sumably a result of large-scale weather condi- 
tions (e.g., precipitation and temperature) just 
before and during the breeding seasons. 
Productivity was poor across most of North 
America, but especially in the eastern third of 
the continent in 1990. Adult population sizes 
declined significantly in the East in 1991, pre- 
sumably a result of the poor productivity in 
1990. In 1992 productivity was poor again in 



Our Living Resoun es Bints 



25 



the East but good in the West. These results sug- 
gest that productivity in a given year may influ- 
ence population sizes and population dynamics 
in subsequent years for many species over a 
large area. 

BBIRD data likewise suggest that weather 
may substantially affect nesting productivity. 
Unusually wet weather conditions were report- 
ed at 6 of 14 BBIRD sites in 1992 when nest 
success of several species, including wood 
thrush {Hylocichla mustelina) and red-eyed 
vireo {Vireo olivaceus), was lower in 1992 than 
in 1993 (Table 1). These same two species also 
had reduced breeding productivity based on 
MAPS data. They produced fewer young per 
successful nest in 1992 than in 1993, a fact 
which also may be related to weather; some 
research suggests that clutch size as well as 
fledging success can be affected by weather 
conditions and may even provide a particularly 
sensitive measure of a species' tolerance to 
changing climatic conditions (e.g., Rotenberry 
and Wiens 1989). Further research may show 
that climatic variability is an important influ- 
ence on the population trends of species. 

Table 1. Wood thrush and red-eyed vireo nest success 
based on May field (1961, 1975) estimates at midwestern 
BBIRD sites during 1992 and 1993 (numbers of nests are 
in parentheses). 



State 


Wood thrush 


Red-eyed 


vireo 


1992 1993 


1992 


1993 


Ohio 


23.0 (52) 33.1 (194) 


6.6(19) 


33.7 (83) 


Arkansas 


45.6(11) 58.0(15) 


35.3 (35) 


42.1 (36) 


Minnesota 




19.0(51) 


23.0 (25) 



Habitat-specific Differences 

Forest fragmentation, where large forest 
blocks are cut and interspersed with open habi- 
tat, is believed to be particularly detrimental for 
breeding nongame birds. For example, BBIRD 
data show that fragmentation was associated 
with lower nest success in several species at 
midwestern BBIRD sites. Ovenbirds (Seiurus 
aurocapillus) were particularly sensitive to 
fragmentation effects; their reduced nest suc- 
cess resulted primarily from increased preda- 
tion, although the parasitism rates of brown- 
headed cowbird (Molothrus ater) were also 
higher in fragments. No clear effect of fragmen- 
tation was noted for red-eyed vireos, although 
nest success differed substantially among 
unfragmented sites, potentially reflecting more 
subtle differences in habitat suitability or land- 
scape-level effects (Table 2). 

Adult Survival in Two Eastern Thrushes 

Analysis of 3 years (1990-92) of MAPS data 
for veery (Catharus fuscescens) and wood 
thrush indicated low and substantially different 



State 


Ovenbird 


Red-eyed vireo 


Fragmented Unfragmented 


Fragmented Unfragmented 


Ohio 


13.7(35) 33.1(45) 


30.0 (52) 24.6 (50) 


Wisconsin 


19.8(30) 42.6(51) 


26.4(13) 50.8(13) 


Arkansas 


51.9(41) 


38.7(71) 


Minnesota 


44.5(159) 


21.0(76) 



(P < 0.06) adult survival probabilities from 
1990 to 1991. According to Breeding Bird 
Survey data, veery populations declined by 
1.0% per year between 1966 and 1991, while 
wood thrush populations showed a statistically 
greater decline of 2.0% per year (Peterjohn and 
Sauer 1993). This difference in population 
declines is mirrored by survival indices; MAPS 
estimates of wood thrush survival are half that 
of the veery, possibly because of differences in 
adult survival over winter. This possibility is 
especially interesting because wood thrushes 
winter in Mexico and Central America where a 
greater proportion of the tropical forests have 
been cleared than in South America where 
veeries winter. Differences in estimated survival 
of the two species, however, could simply 
reflect different life-history traits (e.g., wood 
thrushes having lower adult survival associated 
with higher fertility; Martin in press). Estimated 
survival differences could also result from dif- 
ferences in breeding-site fidelity, which is relat- 
ed to nest success; a variety of evidence shows 
that birds disperse more in breeding seasons 
that follow nesting failure, potentially biasing 
survival estimates. Further nest-monitoring data 
from North America and survivorship data from 
both North America and the Neotropics are 
needed to identify causes of population declines 
in these and other Neotropical migratory land- 
birds. 

Trends 

Preliminary results from the MAPS and 
BBIRD programs suggest that population 
trends of nongame landbirds are influenced by 



Table 2. Ovenbird and red-eyed 
vireo nesl success based on 
May field (1961. 1975) estimates al 
fragmented and unfragmented 
midwestern BBIRD sites during 
1992 and 1993 (numbers of nests 
are in parentheses). 




Monitoring >>i m-sis. mch .is this 
one belonging in .1 red faced wai 
blei i( 'ardeUina rubrifrons), pro- 
vides information on breeding pro 
ductivit] 



26 



Birds — Our Living Resources 



For further information: 

Thomas E. Martin 

National Biological Service 

Cooperative Wildlife Research Unit 

University of Montana 

Missoula, MT 59812 



weather-induced productivity problems, sur- 
vival problems during migration or winter, and 
degradation of breeding habitat. These results 
emphasize the importance of national programs 
such as MAPS and BBIRD in providing base- 
line information on both continental and local 
habitat-specific processes that influence avian 
population dynamics. Ultimately, these data on 
breeding productivity and adult survival and 
their underlying environmental determinants 
will provide information critical for managing 
North American landbirds. 

References 

Baillie, S.R., R.E. Green. M. Body, and S.T. Buckland. 
1993. An evaluation of the constant effort sites scheme. 
British Trust for Ornithology, Thetford. 103 pp. 

DeSante, D.F. 1992. Monitoring Avian Productivity and 
Survivorship (MAPS): a sharp, rather than blunt, tool for 
monitoring and assessing landbird populations. Pages 
511-521 in D.C. McCullough and R.H. Barrett, eds. 
Wildlife 2001: populations. Elsevier Applied Science, 
London. 

DeSante, D.F., and G.R. Geupel. 1987. Landbird productiv- 
ity in central coastal California: the relationship to annu- 
al rainfall, and a reproductive failure in 1986. Condor 
89:636-653. 

DeSante, D.F., K.M. Burton, and O.E. Williams. 1993a. The 
Monitoring Avian Productivity and Survivorship 
(MAPS) program second annual report (1990-1991). 
Bird Populations 1:68-97. 

DeSante, D.F., O.E. Williams, and K.M. Burton. 1993b. The 
Monitoring Avian Productivity and Survivorship 
(MAPS) program: overview and progress. Pages 208-222 



in D.M. Finch and P.W. Stangel, eds. Status and manage- 
ment of Neotropical migratory birds. Gen. Tech. Rep. 
RM-229. U.S. Forest Service, Rocky Mountain Forest 
and Range Experiment Station, Fort Collins, CO. 

Martin, T.E. 1992. Breeding productivity considerations: 
what are the appropriate habitat features for manage- 
ment? Pages 455-473 in J.M. Hagan and D.W. Johnston, 
eds. Ecology and conservation of Neotropical migrants. 
Smithsonian Institution Press, Washington, DC. 

Martin, T.E. Variation and covariation of life history traits of 
birds in relation to nest sites, nest predation, and food. 
Ecological Monographs. In press. 

Martin, T.E., and G.R. Guepel. 1993. Nest-monitoring 
plots: methods for locating nests and monitoring success. 
Journal of Field Ornithology 64:507-519. 

Mayfield, H. 1961. Nesting success calculated from expo- 
sure. Wilson Bull. 73:255-261. 

Mayfield, H. 1975. Suggestions for calculating nest success. 
Wilson Bull. 87:456-466. 

Peterjohn, B.G., and J.R. Sauer. 1993. North American 
Breeding Bird Survey annual summary 1990-1991. Bird 
Populations 1:52-67. 

Pulliam, H.R. 1988. Sources, sinks, and population regula- 
tion. American Naturalist 132:652-661. 

Robbins, C.S., J.R. Sauer, R.S. Greenberg, and S. Droege. 
1989. Population declines in North American birds that 
migrate to the Neotropics. Proceedings of the National 
Academy of Science 86:7658-7662. 

Rotenberry, J.T., and J. A. Wiens. 1989. Reproductive biolo- 
gy of shrubsteppe passerine birds: geographical and tem- 
poral variation in clutch size, brood size, and fledging 
success. Condor 91:1-14. 

Terborgh, J. 1989. Where have all the birds gone? Essays 
on the biology and conservation of birds that migrate to 
the American tropics. Princeton University Press. NJ. 
207 pp. 



Canada Geese 
in North 
America 



by 

Donald H. Rusch 

Richard E. Malecki 

National Biological Service 

Robert Trost 

U.S. Fish and Wildlife 

Service 



Canada geese {Branta canadensis) are prob- 
ably more abundant now than at any time in 
history. They rank first among wildlife watchers 
and second among harvests of waterfowl 
species in North America. Canada geese are 
also the most widely distributed and phenotypi- 
cally (visible characteristics of the birds) vari- 
able species of bird in North America. Breeding 
populations now exist in every province and ter- 
ritory of Canada and in 49 of the 50 United 
States. The size of the 12 recognized subspecies 
ranges from the 1.4-kg (3-lb) cackling Canada 
goose (B.c. minima) to the 5.0-kg (1 1 -lb) giant 
Canada goose (B.c. maxima: Delacour 1954; 
Bellrose 1976). 

Market hunting and poor stewardship led to 
record low numbers of geese in the early 
1900's, but regulated seasons including clo- 
sures, refuges, and law enforcement led to 
restoration of most populations. Winter surveys 
were begun to study population trends and set 
responsible harvest regulations for these 
long-lived and diverse birds. Winter surveys 
begun in 1936-37 probably represent the oldest 
continuing index of migratory birds in North 
America. 



Surveys 

Sporadic counts of migrating and wintering 
Canada geese from the ground were supple- 
mented by regular tallies from the air in the 
early 1950's. Winter surveys began because the 
subarctic and arctic nesting areas of many sub- 
species were still unknown and aerial surveys of 
these remote areas were impractical. 

The well-designed spring surveys of Canada 
geese that began in the 1970's with the Eastern 
Prairie population have now expanded to 
include several others (Office of Migratory Bird 
Management 1993). Spring surveys estimate 
numbers of each population at the time of year 
when subspecies are reproductively isolated and 
geographically separated. The smaller sub- 
species of Canada geese nest farther north (arc- 
tic and subarctic regions of Alaska and Canada), 
and most winter farther south (gulf states and 
Mexico) than do the larger subspecies. 

Status and Trends 

Most aggregations of wintering geese were 
overharvested in the early 1900's. Those 



Our Living Resources llnils 



27 



subspecies that nested in temperate regions 
closer to humans were most heavily hunted. By 
1930 the giant Canada geese, which nested in 
the northern parts of the deciduous forest and 
tall-grass prairie, were believed extirpated. 
Numbers of the large geese that nested in the 
Great Plains and Great Basin (B.c. moffitti) 
were also severely reduced. Small Canada geese 
from the remote arctic and subarctic breeding 
ranges fared somewhat better, possibly because 
of less exposure to unregulated exploitation, but 
were also reduced in number. 

Although hunting depleted numbers of 
Canada geese, human activity also created new 
habitats for these birds. Agriculture led to the 
clearing of forests and the plowing of prairies, 
creating the open landscapes preferred by 
geese. Cereal grains and pastures provided new 
food sources for geese, and the development of 
mechanical combines and pickers created an 
increased supply of waste grain (Hine and 
Schoenfeld 1968). In addition, uniform hunting 
regulations and improved wildlife law enforce- 
ment curtailed goose harvests after the signing 
of the Migratory Bird Treaty in 1916, and most 
goose populations increased over the next sev- 
eral decades (Figure). National wildlife refuges 
provided key sanctuaries and further assisted 
recovery of Canada goose numbers. 

The giant Canada goose was "rediscovered" 
by Harold C. Hanson, a biologist of the Illinois 
Natural History Survey; the publication of his 
book The Giant Canada Goose in 1965 initiat- 
ed a restoration effort that became one of the 
great success stories of wildlife management. 
These large geese were restored to their former 




1 1 1 1 1 1 ii 1 1 1 1 j 1 1 1 1 ii 1 1 1 1 1 1 1 n | M 1 1 1 1 1 1 1 ii 1 1 1 1 1 1 1 1 1 1 1 1 1 ii i] 

36 40 44 48 52 56 60 64 68 72 76 80 84 88 92 
Year 

range in the Mississippi and Central flyways 
and now breed in all states east of the 
Mississippi River. 

Research and improved scientific manage- 
ment led to better understanding of diversity, 
distribution, and population dynamics of 
Canada geese in the 1970's. Awareness of dif- 
ferences in distribution and migration among 
the subspecies allowed managers to effectively 
control goose harvests. Improved management 
led to stable or increasing numbers of Canada 
geese in most populations (Table). The 
Mississippi Flyway Giant, Hi-line, Rocky 
Mountain, and Western Prairie/Great Plains 
populations, all composed mainly of large sub- 
species (B.c. maxima and moffitti), grew at 
about twice the rate of other populations that 
contained mainly smaller subspecies. The pop- 
ulation numbers of the large geese that breed in 
the states of the Atlantic Flyway have also 
increased dramatically, but this trend was 
masked by declining numbers of geese in 



Figure. Total numbers of Canada 

geese counted on winter survej s, 
1936-93. 



Year 



AP 



Population* 



SJBP 



MVP Max(MF) EPP WP/GP TGPP 



SGPP 



H-LP 



RMP 



DSKY 



CCG 



1969-70 


775.2 


106.9 


324.7 


50.8 


106.6 






151.2 


44.2 


25.8 


22.5 




1970-71 


675.0 


127.3 


292.3 


64.4 


126.3 




133.2 


148.5 


40.5 


25.3 


19.8 




1971-72 


700.2 


117.6 


293.9 


55.8 


157.4 




160.9 


160.9 


31.4 


36.6 


17.9 




1972-73 


712.0 


101.3 


295.9 


54.2 


181.4 




148.4 


259.4 


35.6 


37.1 


15.8 




1973-74 


760.2 


136.0 


277.9 


57.6 


205.8 




160.5 


153.6 


24.5 


42.8 


18.6 




1974-75 


819.3 


101.0 


304.4 


57.0 


197.1 




133.5 


123.7 


41.2 


46.7 


26.5 




1975-76 


784.5 


115.5 


304.9 


62.1 


204.4 




203.7 


242.5 


55.6 


51.6 


23.0 




1976-77 


923.6 


129.8 


478.5 


58.5 


254.2 




171.3 


210.0 


67.6 


54.3 


24.1 




1977-78 


833.2 


180.4 


575.5 


60.1 


270.2 




215.5 


134.0 


65.1 


59.0 


240 




1978-79 


823.6 


142.7 


434.5 


77.1 


207.2 




187.6 


163.7 


33.8 


62.7 


25.5 




1979-80 


780.1 


127.0 


394.9 


86.4 


171.8 




165.9 


213.0 


67.3 


77.3 


22.0 


64.1 


1980-81 


955.0 


120.3 


367.4 


102.9 


150.9 




257.7 


168.2 


94.4 


93.8 


23.0 


127.4 


1981-82 


702.6 


118.5 


250.9 


107.6 


145.3 


175.0 


284.7 


156.0 


81.9 


64.3 


177 


87 1 


1982-83 


888.7 


129.9 


303.7 


149.9 


213.4 


242.0 


171.8 


173.2 


75.9 


68.2 


17.0 


54.1 


1983-84 


822.4 


129.9 


352.8 


103.9 


163.1 


150.0 


279.9 


143.5 


39 5 


55.5 


10.1 


262 


1984-85 


814.2 


129.3 


477.2 


151.7 


168.4 


230.0 


207.0 


179.1 


76.4 


90.3 


7.5 


25.8 


1985-86 


905.4 


158.0 


618.9 


180.1 


169.0 


115.0 


198.2 


181.0 


69.8 


683 


122 


32 1 


1986-87 


754.8 


129.8 


514.6 


231.9 


183.4 


324.0 


163.2 


190.9 


98 1 


71.5 




51.4 


1987-88 


737.9 


158.8 


564.6 


225.9 


228.5 


272.1 


315.8 


139.1 


66.8 


71.4 


12.2 


54.8 


1988-89 


660.7 


170.2 


734.6 


252.2 


184.5 


330.3 


224.2 


284.8 


100.1 


73.9 


11.8 


69.9 


1989-90 


733.8 


159.4 


1098.2 


284.3 


324.9 


271.0 


159.0 


378.1 


105.9 


1024 


11.7 


768 


1990-91 


706.9 


142.2 


939.7 


345.1 


218.4 


390.0 


315.5 


508.5 


116.6 


86.7 




110.2 


1991-92 


654.5 


107.2 


766.8 


234.8 


189.4 


341.9 


280.4 


620.2 


140.5 


115.7 


180 


1046 


1992-93 


569.2 


104.4 


673.4 


282.6 


146.4 


318.0 


238.7 


328.2 


118.5 


99.5 


16.6 


149.3 



'Populations are Atlantic (AP), Southern James Bay (SJBP), Mississippi Valley (MVP), Mississippi Flyway Giant (Max[MF]), Eastern Prairie (EPP). 
Western Prairie/Great Plains (WP/GP), Tall-grass Prairie (TGPP), Short-grass Prairie (SGPP), Hi-line (H-LP). Rocky Mountain (RMP). Dusky (DSKY), and 
Cackling Canada Goose (CCG). 



Table. Canada goose population 
indices (in 1,000's) based on sur- 
veys conducted during tall and 
winter. 1969-93. 



28 



Birds — Our Living Resources 



For further information: 

Donald H. Rusch 

National Biological Service 

Wisconsin Cooperative Wildlife 

Research Unit 

University of Wisconsin 

Madison, WI 53706 



Canada's eastern subarctic regions. 

Although small geese with long migrations 
have generally not fared as well as large geese 
with short migrations, some small geese have 
responded well to intensive management. 
Introduced Arctic foxes (Alopex lagopus) 
depleted populations of the Aleutian Canada 
goose (B.C. leucopareia), and the subspecies 
was nearly extinct by 1940. About 300 were 
rediscovered in the Aleutians on Buldir Island 
in 1962 (Jones 1963). Subsequent removal of 
foxes and translocation of wild geese have led 
to increases to about 750 geese in 1975 and 
more than 11,000 in 1993. 

Heavy hunting caused numbers of cackling 
Canada geese to plummet to record lows in the 
early 1980's, but intensive research (Raveling 
and Zezulak 1992) and harvest control have 
brought about a sustained recovery (Table). 

Recent genetic studies of Canada geese sup- 
port the existence of two major groups that last 
shared a common ancestor about 1 million years 
ago. The large-bodied group (B.c. canadensis, 
interior, maxima, moffitti, fulva, occidentalis) is 
mainly continental in distribution, while the 
small-bodied group (hutchinsii, taverneri, mini- 
ma, leucopareia) breeds in coastal Alaska and 
Arctic Canada (Rusch et al. in press). 

The future of these diverse stocks of Canada 
geese depends upon information adequate to 
permit simultaneous protection of rare forms, 
responsible subsistence and recreational hunt- 
ing of abundant populations, and control of nui- 
sance Canada geese in urban and suburban envi- 
ronments. Delineation of breeding ranges and 
spring surveys that monitor numbers of pairs 



and their productivity offer the most realistic 
approach to population management and the 
conservation of this remarkable diversity of 
geese. 

Ranges of most populations have been 
described, and spring surveys are in place for 
some. Development and continuation of spring 
surveys for each subspecies of Canada geese are 
prerequisites for their conservation and man- 
agement. The species can no doubt be perpetu- 
ated without spring surveys, but without contin- 
ued monitoring, management, and conserva- 
tion, it is likely that rare forms will disappear, 
opportunities for subsistence and recreational 
hunting will diminish, and nuisance problems 
caused by large geese living near humans will 
increase. 

References 

Bellrose, F.C. 1976. Ducks, geese and swans of North 
America. Stackpole, Harrisburg. PA. 544 pp. 

Delacour. J.T. 1954. The waterfowl of the world. Vol. 1. 
Country Life, Ltd., London. 251 pp. 

Hanson, H.C. 1965. The giant Canada goose. Southern 
Illinois University Press. Carbondale. 226 pp. 

Hine, R.L., and C. Schoenfeld, eds. 1968. Canada goose 
management. Denbar Educational Research Services. 
Madison, WI. 194 pp. 

Jones, R.D., Jr. 1963. Buldir Island, site of a remnant popu- 
lation of Aleutian Canada geese. Wildfowl 14:80-84. 

Office of Migratory Bird Management. 1993. Status of 
waterfowl and fall flight forecast. U.S. Fish and Wildlife 
Service, Washington. DC. 37 pp. 

Raveling. D.G.. and D.S. Zezulak. 1992. Changes in distri- 
bution of cackling Canada geese in autumn. California 
Fish and Game 78:65-77. 

Rusch, D.H.. D.D. Humburg. M.D. Samuel, and B.D. 
Sullivan, eds. 1994. Biology and management of Canada 
geese. Proceedings of the 1991 International Canada 
Goose Symposium. In press. 



Canada Geese 
in the Atlantic 
Flyway 



by 

Jay B. Hestbeck 
National Biological Service 



Large changes have occurred in the geo- 
graphic wintering distribution and sub- 
species composition of the Atlantic Flyway 
population of Canada geese (Branta canaden- 
sis) over the last 40 years. The Atlantic Flyway 
can be thought of as being partitioned into four 
regions: South, Chesapeake, mid-Atlantic, and 
New England. Wintering numbers have 
declined in the southern states (North Carolina, 
South Carolina, Georgia, Florida), increased 
then decreased in the Chesapeake region 
(Delaware, Maryland, Virginia), and increased 
markedly in the mid- Atlantic region (New York, 
New Jersey, Pennsylvania, West Virginia) (Serie 
1993; Fig. 1). In the New England region 
(Maine, New Hampshire, Vermont, 
Massachusetts, Rhode Island, Connecticut), 
wintering numbers increased from around 6,000 
during 1948-50 to between 20,000 and 30,000 
today (Serie 1993). 

Overall, the total number of wintering geese 
reached a peak of 955,000 in 1981 and has since 
declined 40% to 569,000 in 1993. 



Compounding these distributional changes in 
wintering numbers, the subspecies composition 
has also changed. The Canada goose population 
is composed of migrant geese (primarily B.c. 




Year 

Fig. 1. Midwinter number of Canada geese in mid- 
Atlantic. Chesapeake, and South regions of the Atlantic 
Flyway. 1948-93 (Midwinter Survey, U.S. Fish and 
Wildlife Service. Office of Migratory Bird Management) 



Our living Resources - Birds 



29 



canadensis and B.c. interior) that breed in the 
subarctic regions of Canada and resident geese 
(primarily B.c. maxima and B.c. moffitti) that 
breed in southern Canada and the United States 
(Stotts 1983). The number of resident geese in 
Maine to Virginia has increased considerably 
from maybe 50,000 to 100,000 in 1981 
(Conover and Chosko 1985) to an average of 
560,000 in 1992-93 (H. Heusman, 
Massachusetts Division of Fisheries and 
Wildlife, personal communication). This rapid 
increase in resident geese suggests that the 
migrant population has declined more than the 
40% decline observed in total wintering geese 
from 1981 to 1993. 

Population Changes 

Changes in population numbers result from 
changes in production, survival, and movement, 
acting singly or in combination. Consequently, 
understanding the reason for population 
changes involves detecting variation in survival, 
production, and movement over time and relat- 
ing that variation to changes in wintering num- 
bers. During the 1970's, the decrease of winter- 
ing geese in the South and increase in the 
Chesapeake region appeared to result from 
increased survival of geese in the Chesapeake 
and possibly from movement or short-stopping 
of geese from the South to the Chesapeake 
(Trost et al. 1986). Short-stopping occurs when 
migrant geese winter in a more northern loca- 
tion than their traditional, more southern, 
migration terminus. 

During the 1980's, the decrease of wintering 
geese in the Chesapeake appeared to result from 
an 11% decrease in average survival from 1963- 
74 to 1984-88 (Hestbeck 1994a). This decrease 
in survival corresponded to a 36% increase in 
average harvest rate for the Atlantic Flyway 
from 1963-74 to 1984-88 (Fig. 2). Overall, the 
flyway harvest rate, as a 3-year average, 
increased from 19% in 1962-64 to 34% in 1982- 
84, and then slowly declined to 31% by 1990- 
92. The eastern Canada harvest rate has slowly 
increased from 4.2% in 1968-70 to 8.1% in 
1990-92. The slight decline in the harvest rate in 
the flyway since 1982-84 has been partially off- 
set by harvest rate increases in eastern Canada. 

The decrease in number of geese wintering 
in the Chesapeake region in the 1980's was not 
related to changes in production. Production for 
migrants, measured from the Canadian data, 
remained constant over the period of population 
decline in the Chesapeake (Fig. 3). Average pro- 
duction recently declined during 1991-92 for 
geese harvested in Quebec. I also used harvest 
age ratios for the mid- Atlantic and Chesapeake 
regions to test for differences in production 
between these regions (Hestbeck 1994b). If the 




changes in wintering number resulted from 
changes in production, the average annual 
change in the age ratios would be higher for the 
mid-Atlantic region than for the Chesapeake 
region. The average annual changes were not 
different between these regions, however, indi- 
cating that regional production differences were 
not present. 

The decrease in number of geese wintering 
in the Chesapeake region in the 1980's was not 
caused by migrant geese short-stopping in the 
mid-Atlantic instead of returning to the 
Chesapeake. From neck-band data, the proba- 
bility of returning or moving to the different 
regions was estimated and indicated that, 
although geese traditionally returned to the 
same wintering area, they also changed winter- 
ing areas from year to year (Hestbeck 1994b). 
In years with harsher winters, geese wintered 
farther south than during milder winters 
(Hestbeck et al. 1991). Overall, the probability 
of returning or moving to the Chesapeake 
region was higher than the probability of return- 
ing or moving to any other region. When popu- 
lation size, survival, and movement were com- 
bined to estimate net movement among regions, 
the estimated net movements among regions 
were small and did not correspond to the 
changes in numbers of wintering geese. Taken 



Flying neck-banded goose {Brania 
canadensis). 



0.40 




0.00 1 

62 67 72 77 82 87 92 

Year 



Hy. -■ Harvesl rate of Canada 
geese in the Atlantic I lyway, 1962 
92 - Harvesl and Midwintei 
Surveys, U S Fish and Wildlife 
Service, Office ol Migrator) Hud 
Management) and eastern Canada, 
1968 92 (Harvesl Survey, < .ni.idi.ni 
Wildlife Service, National Wildlife 
Research ( Centre) 



30 



Birds — Our Living Resources 



Fig. 3. Production ratio of Canada 
geese in Quebec and Atlantic 
regions of eastern Canada, 1975- 
93 (Waterfowl Parts Collection 
Survey, Canadian Wildlife Service, 
Atlantic Region, Sackville, N.B.). 



For further information: 

Jay B. Hestbeck 

National Biological Service 

Massachusetts Cooperative Fish 

and Wildlife Research Unit 

University of Massachusetts 

Box 34220 

Amherst, MA 01003 







A Atlantic 


? n 






~ /\ hl\ 


I aW\/)H\/)A / 


" | V V y v\J/ 










Quebec 




0.0- 


i i i i i i i 


i i i i i i i i i i i i 



75 



81 

Year 



87 



93 



together, these results suggested that the 
increases in the number of wintering geese in 
the mid-Atlantic region did not result from 
short-stopping of geese. 

The increase of wintering geese in the mid- 
Atlantic most likely resulted from expanding 
resident populations. Resident geese generally 
have larger body sizes, allowing them to winter 
farther north than smaller-bodied migrant geese 
(Lefebvre and Raveling 1967). Resident and 
migratory-resident geese may selectively 
remain in the mid-Atlantic region. In addition, 
the resident population may be increasing faster 
than the migrant population because survival 
and production appear higher for residents than 
for migrants. Residents survive better partly 
because they are familiar with areas of food and 
refuge and may avoid hunting areas (Johnson 
and Castelli 1994). Production may be higher 
for resident than migrant geese because the cli- 
mate is less variable and milder with a longer 
growing season in southern Canada and the 



United States than in the subarctic. Resident 
geese may also reach reproductive age earlier 
than migrant geese because the southerly grow- 
ing season is longer, providing greater food 
resources. 

References 

Conover, M.R., and G.G. Chasko. 1985. Nuisance Canada 
goose problems in the eastern United States. Wildlife 
Society Bull. 13:228-233. 

Hestbeck, J.B. 1994a. Survival of Canada geese banded in 
winter in the Atlantic Flyway. Journal of Wildlife 
Management 58(4): 748-756. 

Hestbeck, J.B. 1994b. Changing number of Canada geese 
wintering in different regions of the Atlantic Flyway. In 
D.H. Rusch. D.D. Humburg, M.D. Samuel, and B.D. 
Sullivan, eds. Proceedings of the 1991 International 
Canada Goose Symposium. Milwaukee, WI. In press. 

Hestbeck, J.B.. J.D. Nichols, and R.A. Malecki. 1991. 
Estimates of movement and site fidelity using mark- 
resight data of wintering Canada geese. Ecology 72:523- 
533. 

Johnson. FA., and P.M. Castelli. 1994. Demographics of 
Canada geese breeding in southeastern Canada and the 
northeastern United States. In D.H. Rusch, D.D. 
Humburg. M.D. Samuel, and B.D. Sullivan, eds. 
Proceedings of the 1991 International Canada Goose 
Symposium. Milwaukee, WI. In press. 

Lefebvre, E.A., and D.G. Raveling. 1967. Distribution of 
Canada geese in winter as related to heat loss at varying 
environmental temperatures. Journal of Wildlife 
Management 31:538-546. 

Serie, J. 1993. Waterfowl harvest and population survey 
data. U.S. Fish and Wildlife Service, Office of Migratory 
Bird Management, Laurel. MD. 68 pp. 

Stotts, V.D. 1983. Canada goose management plan for the 
Atlantic Flyway, 1983-95. Part 2. History and current sta- 
tus. The Atlantic Flyway Waterfowl Council, mimeo. 

Trost, R.E., R.A. Malecki, L.J. Hindman, and D.C. Luszcz. 
1986. Survival and recovery rates of Canada geese from 
Maryland and North Carolina 1963-1974. Proceedings of 
the Annual Conference of the Southeastern Association 
of Fish and Wildlife Agencies 40:454-464. 



Arctic Nesting 
Geese: 
Alaskan 
Populations 

by 

Jerry Hupp 

Robert Stehn 

Craig Ely 

Dirk Derksen 

National Biological Service 



North American populations of most goose 
species have remained stable or have 
increased in recent decades (USFWS and 
Canadian Wildlife Service 1986). Some popula- 
tions, however, have declined or historically 
have had small numbers of individuals, and thus 
are of special concern. Individual populations 
of geese should be maintained to ensure that 
they provide aesthetic, recreational, and ecolog- 
ical benefits to the nation. Monitoring and man- 
agement efforts for geese should focus on indi- 
vidual populations to ensure that genetic diver- 
sity is maintained (Anderson et al. 1992). 

Alaska is the only state with viable breeding 
populations of arctic geese. Five species ( 1 1 
subspecies) nest in Alaska, and although these 
species also breed in arctic regions of Canada or 
Russia, most geese of the Pacific Flyway origi- 
nate in Alaska or use Alaskan habitats during 
migration. Alaskan geese are often hunted for 



subsistence by Alaskan Natives. 

While data for some areas are lacking, pop- 
ulations of greater white-fronted geese (Anser 
albifrons frontalis) and medium-sized Canada 
geese (Branta canadensis) in interior and north- 
ern Alaska appear stable or have increased 
(King and Derksen 1986). Although only a 
small number of lesser snow geese {Chen 
caerulescens caerulescens) nest in Alaska, sub- 
stantial populations occur in Canada and 
Russia. Populations of Pacific black brant (B. 
bemicla nigricans), emperor geese (C canagi- 
ca). greater white-fronted geese, and cackling 
Canada geese (B.c. minima) on the Yukon- 
Kuskokwim Delta (YKD) of western Alaska 
have declined from their historical numbers and 
are the focus of special management efforts 
(USFWS 1989). In addition, populations of tule 
white-fronted geese (A. a. gambeli), Aleutian 
Canada geese (B.c. leucopareia), Vancouver 



Our Living Resources Hud\ 



il 



Canada geese (B.c. fulva), and dusky Canada 
geese (B.c. occidentalis) are of special concern 
because of their limited geographic distribu- 
tions and small numbers. 

Inventory of Arctic Geese 

An annual index of the Pacific black brant 
population has been obtained since 1964 by the 
U.S. Fish and Wildlife Service (USFWS) during 
aerial surveys of wintering areas along the 
Pacific coast (Bartonek 1994a). Population 
trends of cackling Canada geese and greater 
white-fronted geese from 1965 to 1979 were 
based on surveys conducted by USFWS and 
state agency biologists on migration areas in the 
Klamath Basin of Oregon and California. 
Population trends of those two species from 
1980 to 1993 were based on coordinated sur- 
veys on wintering areas (Bartonek 1994b). 

Emperor geese have been inventoried by 
USFWS biologists during aerial surveys of 
spring and fall migration areas on the Alaska 
Peninsula and the YKD since 1980 (Bartonek 
1992). We used the highest count within a year 
to determine the population trend for emperor 
geese. Population indices for tule white-fronted 
geese were obtained from surveys on wintering 
and migration areas in the Pacific Flyway in 
intermittent years since 1978. Aleutian Canada 
geese have been counted on a spring staging 
area in northern California since 1975. Dusky 
Canada geese have been inventoried on their 
wintering areas in the Pacific Flyway since 
1953. There are no data on population trends of 
Vancouver Canada geese; however, the winter 
population in the northern portion of southeast- 
ern Alaska was estimated by USFWS biologists 
in 1986. 

Status of Alaskan Geese 

Yukon-Kuskokwim Delta Geese 

Most geese on the YKD nest within 30 km 
(15-20 mi) of the Bering Sea but winter in 
diverse areas. Pacific black brant primarily win- 
ter along the Pacific coast of Mexico while 
greater white-fronted geese and cackling 
Canada geese primarily winter in the Central 
Valley of California. In recent years, increasing 
numbers of cackling Canada geese have win- 
tered in Oregon. Most emperor geese winter in 
the Aleutian Islands. 

These four species experienced sharp popu- 
lation declines (30%-50%) between the early 
1960's and mid-1980's (Fig. 1). The declines 
were likely due to the combined effects of sub- 
sistence harvest of breeding birds and eggs on 
the YKD, excessive sport harvest on the winter- 
ing areas, poor weather during nesting, and fox 



predation of nests (USFWS 1989). In 1984, the 
USFWS, Yupik Natives, state wildlife agencies, 
and sport hunters cooperated to reduce sport 
and subsistence harvest. Since then populations 
of cackling Canada geese and greater white- 
fronted geese have begun to recover while 
emperor geese and black brant remain near his- 
torical lows (Fig. 1). Poor winter survival of 
juvenile emperor geese may be slowing recov- 
ery of that species (Schmutz et al. 1994). Winter 
survival of cackling Canada geese has improved 
since the reduction in sport hunting; however, 
there is no evidence that their survival in sum- 
mer has improved (Raveling et al. 1992). 

Tule White-fronted Geese 

The only known nesting area for tule white- 
fronted geese is in Upper Cook Inlet (Timm et 
al. 1982) and the adjacent Susitna in south-cen- 
tral Alaska. Tule geese may also occur on the 
Innoko National Wildlife Refuge in western 
Alaska. The numbers of tule geese counted on 
wintering areas in the Central Valley of 
California in recent years are higher than during 
the late i970's (Fig. 2). It is unclear if the 
increase is due to population growth or because 
of improved understanding of the winter distri- 
bution. 




500 
__ 400 
| 300 
S 200 
I 100 

o 

1 ° 

I 150 

H 12 ° 

I 90 

i 

S 60 

30 





While-fronted geese 



no 



?at a ~ 



Emperor geese 




40 




64 67 70 73 



76 79 
Year 



82 85 





I 91 



Ki>;. l Population trends ol arctic 
geese t li.it nesi on the Yukon 
Kuskokwim Delta, Alaska I 1964- 
93) 



32 



Birds — Our Living Resources 



Fig. 2. Population trends of 
Aleutian Canada geese (1975-93), 
dusky Canada geese (1953-93), 
and tule white-fronted geese 
(1978-89). 




S 30 

CD 

°- 26 




*\o°.-- 



Tule white-fronted geese 



~i — i — i — i — i — i — i — i — i — i — i — i — i — i — i — 
78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 

Year 

Dusky Canada Geese 

Dusky Canada geese primarily nest on the 
Copper River Delta of south-central Alaska, the 
islands of Prince William Sound, and Middleton 
Island in the Gulf of Alaska. They winter in the 
Willamette Valley of Oregon and the lower 
Columbia River. The population was stable or 
increased between the 1950's and 1970's. 
During the early 1980's, however, the popula- 
tion declined, then stabilized at a lower level in 
the mid-1980's (Fig. 2). The decline was large- 
ly due to reduced nesting success as a result of 
habitat changes on the nesting area following 
the 1964 Alaska earthquake. Invasion of shrubs 
and loss of wet meadow habitats resulted in 
more mammalian predators and greater nest 
predation (Subcommittee on Dusky Canada 
Geese 1992). 

Aleutian Canada Geese 

Although once abundant on the Aleutian, 
Commander, and Kuril islands, the numbers of 
Aleutian Canada geese were greatly reduced by 
foxes and dogs introduced to nesting islands by 
commercial fur farmers before World War II 
(Byrd and Woolington 1983). The subspecies 
was classified as endangered in 1967, and by 
the mid-1970's fewer than 800 individuals 
remained (USFWS 1991). Sport harvest on 
migration and wintering areas in Oregon and 



California was stopped in 1975, and fox control 
was initiated on nesting islands. Geese were 
also transplanted to fox-free islands. The popu- 
lation of Aleutian Canada geese responded to 
recovery efforts and has grown to more than 
9,000 individuals (Fig. 2). The status of the sub- 
species was changed from endangered to threat- 
ened in 1991. 

Vancouver Canada Geese 

Vancouver Canada geese nest and use 
brood-rearing areas in southeastern Alaska 
(Lebeda and Ratti 1983) and winter on coastal 
wetlands near the breeding areas. Few data on 
breeding numbers exist because Vancouver 
Canada geese nest in coastal forests and are dif- 
ficult to survey. About 1 0,000 Vancouver Canada 
geese wintered in the northern portion of south- 
eastern Alaska in 1986 (Hodges and Conant 
1986). Wintering sites are scattered among 
coastal wetlands and have not been consistently 
surveyed. Consequently, population trends of 
this subspecies are not known. Population trends 
are likely influenced by environmental variables 
because sport and subsistence harvest are mini- 
mal (King and Derksen 1986). 

Status of Habitats of Special 
Concern 

Yukon-Kuskokwim Delta 

The YKD (Fig. 3) is the primary waterfowl 
nesting area in Alaska (King and Dau 1981); it 
provides critical nesting and brood-rearing 
habitat for more than 400,000 geese. In addi- 
tion, the entire population of Wrangel Island 
lesser snow geese uses the YKD during fall 
staging (Ely et al. 1993). While much of the 
YKD is within the Yukon Delta National 
Wildlife Refuge, it is also a region where more 
than 17,000 Yupik Natives live in 40 Native vil- 
lages. Large private inholdings. primarily 
Native corporation lands, exist within the refuge 
and contain important waterfowl nesting habi- 
tat. Meeting the subsistence needs of Native 
people while maintaining or enhancing water- 
fowl populations on the YKD requires close 
coordination among the Yupik Natives and fed- 
eral and state agencies. Management of subsis- 
tence waterfowl harvest on the YKD has been 
difficult because of cultural differences and 
constraints imposed by the Migratory Bird 
Treaty Act. Coordinated management efforts 
will be especially important in the future as 
Native populations increase. 

Izembek Lagoon 

Nearly the entire world population of more 
than 120,000 Pacific black brant uses Izembek 



Our Living Resources — limls 



33 



Lagoon (Fig. 3) as a fall staging area for about 
2 months. Although Izembek Lagoon is protect- 
ed as a national wildlife refuge and state game 
refuge, it is near offshore oil leases in Bristol 
Bay. Should oil development proceed, increased 
aircraft activity over Izembek Lagoon could 
result in a significant increase in disturbance 
that could prevent brant from accumulating suf- 
ficient body fat for their nonstop flight to win- 
tering areas in Mexico. This lack of sufficient 
body fat could result in increased mortality 
(Wardetal. 1994). 

Bristol Bay Lowlands 

Estuaries on the north side of the Alaska 
Peninsula (Fig. 3) provide critical migration 
habitat for cackling Canada geese, Taverner's 
Canada geese (B. c. taverneri), and emperor 
geese, and nesting habitat for a unique group of 
greater white-fronted geese. Part of this area is 
protected in State Critical Habitat Areas man- 
aged by the Alaska Department of Fish and 
Game. At least 5,265 ha (13,000 acres) of 
important habitat, however, is state land that 
may be subject to resource development. 

Teshekpuk Lake Special Areas 

Up to 32,000 Pacific black brant (25% of the 
world population) and 30,000 individuals of 
other goose species molt annually on 
Teshekpuk Lake Special Area (TLSA) (Fig. 3) 
on the National Petroleum Reserve in Alaska 
(Derksen 1978; King 1984). The area is man- 
aged by the Bureau of Land Management, and 
special regulations govern resource develop- 
ment on the TLSA to minimize adverse impacts 
to wildlife. Energy development in adjacent 
areas, though, may result in increased aircraft 
activity that could disturb molting geese and 
reduce their ability to secure forage needed for 
feather replacement (Jensen 1990). 

Interior Wetlands 

Greater white-fronted and Canada goose- 
nesting and brood-rearing habitats occur in inte- 
rior wetlands near the Yukon, Tanana, 
Kuskokwim, Koyukuk, Susitna, and Innoko 
rivers (King and Lensink 1971). National 
wildlife refuges encompass much of the impor- 
tant habitat, although some areas are managed 
by the state of Alaska, private landowners, and 
the Bureau of Land Management. At present, 
there is relatively little human-related distur- 
bance in these areas, although placer mining, oil 
exploration and development, timber harvest, 
and military training could affect some areas. 

Upper Cook Inlet 

About 100,000 geese and swans use Upper 
Cook Inlet (Fig. 3) as spring migration habitat. 



Teshekpuk Lake 
Special Area 



Arctic National 
Wildlife Reluge 




In addition, this inlet is one of two nesting areas 
of tule white-fronted geese. Development of oil 
and gas, coal, timber, and mineral deposits has 
either been proposed or is ongoing in Upper 
Cook Inlet and may affect coastal wetlands used 
by migratory waterfowl. Most of the important 
waterfowl habitats in this area are state game 
refuges or Critical Habitat Areas managed by 
the Alaska Department of Fish and Game. 

Alaska Coastal Forests 

Some nesting and brood-rearing areas of 
Vancouver Canada geese (Fig. 3) occur in areas 
of commercially harvestable timber (Lebeda and 
Ratti 1983). Logging activities on U.S. Forest 
Service land on the Tongass National Forest 
could affect these habitats. In addition, timber 
harvest on Native corporation lands may restrict 
opportunities to transplant Vancouver Canada 
geese into areas of suitable habitat or may limit 
natural expansion of the subspecies range (King 
and Derksen 1986). Use of tidal areas to store 
harvested timber before shipping can affect win- 
tering habitat of Vancouver Canada geese and 
migration habitats of other waterbirds. 

Arctic National Wildlife Refuge 

As many as 300,000 lesser snow geese and 
an unknown number of greater white-fronted 
geese stage on the Arctic National Wildlife 
Refuge (Fig. 3) before fall migration. During 
staging, geese feed intensively and build fat 
reserves for migration. Proposed petroleum 
leases on the refuge would result in increased 
aircraft activity that could disrupt feeding 
behavior of geese, displace birds from feeding 



Fig. 3. Alaskan habitats of special 
importance to geese. 



34 



Birds — Our Living Resources 



For further information: 

Jerry Hupp 

National Biological Service 

Alaska Science Center 

1011 E.Tudor Road 

Anchorage, AK 99503 



habitats, and reduce their ability to accumulate 
body fat before migration (Brackney et al. 
1987). Diminished fat reserves could reduce 
survival during migration. 

References 

Anderson, M.G., J.M. Rhymer, and EC. Rohwer. 1992. 
Philopatry, dispersal, and the genetic structure of water- 
fowl populations. Pages 365-395 in B.D.J. Batt, A.D. 
Afton, M.G. Andersen. CD. Ankney, D.H. Johnson, J. A. 
Kadlec, and G.L. Krapu, eds. Ecology and management 
of breeding waterfowl. University of Minnesota Press, 
Minneapolis. 

Bartonek, J.C. 1992. 1992 Pacific Flyway briefing material. 
U.S. Fish and Wildlife Service, Portland, OR. 90 pp. 

Bartonek, J.C. 1994a. Pacific brant Midwinter Survey 
January 1993. U.S. Fish and Wildlife Service, Portland, 
OR. 4 pp. 

Bartonek, J.C. 1994b. 1993 Pacific Flyway fall and winter 
goose surveys. U.S. Fish and Wildlife Service, Portland, 
OR. 8 pp. 

Brackney, A.W., R.M. Platte, J.M. Morton, and D. Whiting. 
1987. Ecology of lesser snow geese staging on the 
Coastal Plain of the Arctic National Wildlife Refuge, fall 
1985. Pages 372-392 in G.W. Garner and P.E. Reynolds, 
eds. 1985 Update report, baseline study of the fish, 
wildlife, and their habitats. Vol. 1. U.S. Fish and Wildlife 
Service, Anchorage, AK. 

Byrd, G.V., and D.W. Woolington. 1983. Ecology of 
Aleutian Canada Geese at Buldir Island, Alaska. U.S. 
Fish and Wildlife Service Special Scientific Report- 
Wildlife, 253. 18 pp. 

Derksen, D.V. 1978. Summary of Teshekpuk Lake aerial 
goose surveys (1976-1978). U.S. Fish and Wildlife 
Service, Anchorage, AK. 20 pp. 

Ely, C.E., J.Y. Takekawa. and M.L. Wege. 1993. 
Distribution, abundance, and productivity of Wrangel 
Island lesser snow geese Anser caerulescens during 
autumn migration on the Yukon-Kuskokwim Delta. 
Alaska. Wildfowl 44:24-32. 

Hodges, J. I., and B. Conant. 1986. Experimental Canada 
goose survey northern portion of southeast Alaska. U.S. 
Fish and Wildlife Service. Juneau, AK. 9 pp. 

Jensen, K.C. 1990. Responses of molting Pacific black 
brant to experimental aircraft disturbance in the 



Teshekpuk Lake Special Area. Alaska. Ph.D. disserta- 
tion. Texas A & M University, College Station. 72 pp. 

King, J.G., and D.V. Derksen. 1986. Alaska goose popula- 
tions: past, present, and future. Transactions of the North 
American Wildlife and Natural Resources Conference 
51:464-479. 

King, J.G., and C.P. Dau. 1981. Waterfowl and their habitats 
in the eastern Bering Sea. Pages 739-753 in D.W. Hood 
and J. A. Calder, eds. The eastern Bering Sea shelf: 
oceanography and resources. Vol. 2. University of 
Washington Press, Seattle. 

King, J.G., and C.J. Lensink. 1971. An evaluation of 
Alaskan habitat for migratory birds. U.S. Fish and 
Wildlife Service, Washington, DC. 45 pp. 

King, R.J. 1984. Results of the 1982 and 1983 aerial goose 
surveys at Teshekpuk Lake, Alaska. U.S. Fish and 
Wildlife Service. Fairbanks, AK. 10 pp. 

Lebeda, C.S., and J.T. Ratti. 1983. Reproductive biology of 
Vancouver Canada geese on Admiralty Island, Alaska. 
Journal of Wildlife Management 47:297-306. 

Raveling, D.G., J.D. Nichols, J.E. Hines. D.S. Zezulak, J.G. 
Silveira, J.C. Johnson, T.W. Aldrich, and J. A. Weldon. 
1992. Survival of cackling Canada geese, 1982-1988. 
Journal of Wildlife Management 56:63-73. 

Schmutz, J.A., S.E. Cantor, and M.R. Petersen. 1994. 
Seasonal and annual survival of emperor geese. Journal 
of Wildlife Management 58:525-535. 

Subcommittee on Dusky Canada Geese. 1992. Pacific 
Flyway management plan for dusky Canada geese. 
Pacific Flyway Study Committee, U.S. Fish and Wildlife 
Service. Portland. OR. 28 pp. 

Timm, D.E.. M.L. Wege, and D.S. Gilmer. 1982. Current 
status and management challenges for tule white-fronted 
geese. Transactions of the North American Wildlife and 
Natural Resources Conference 47:453-463. 

USFWS and Canadian Wildlife Service. 1986. North 
American Waterfowl Management Plan. U.S. Fish and 
Wildlife Service. Washington, DC. 19 pp. 

USFWS. 1989. Comprehensive management plans for arc- 
tic nesting geese in Alaska. U.S. Fish and Wildlife 
Service, Anchorage, AK. 107 pp. 

USFWS. 1991. Aleutian Canada goose recovery plan. U.S. 
Fish and Wildlife Service, Anchorage. AK. 55 pp. 

Ward, D.H., R.A. Stehn, and D.V. Derksen. 1994. Response 
of staging brant to disturbance at the Izembek Lagoon. 
Alaska. Wildlife Society Bull. 22:220-228. 



North 

American 

Ducks 

by 

David F. Caithamer 

Graham W. Smith 
U.S. Fish and Wildlife Service 



Increased predation and habitat degradation 
and destruction coupled with drought, espe- 
cially on breeding grounds, have caused the 
declines of some duck populations. More than 
30 species of ducks breed in North America, in 
areas as diverse as the arctic tundra and the sub- 
tropics of Florida and Mexico. For many of 
these species, however, the Prairie Pothole 
region of the north-central United States and 
south-central Canada is the most important 
breeding area (Fig. 1 ), although migratory 
behavior and the life histories of different 
species lead them to use many wetland habitats. 
Numerous sources of information are avail- 
able on the status of duck populations in North 
America. The two most comprehensive and 
reliable sources are the Breeding Population 
and Habitat Survey, conducted since 1955 and 
encompassing the Prairie Pothole region, bore- 
al forests, and tundra habitats from South 




^Breeding 
Population 
and Habitat Surve' 

Q Prairie Pothole 
region 



Fig. 1. The Prairie Pothole region and areas sampled in 
ihe Breeding Population and Habitat Survey. 

Dakota to Alaska (Caithamer et al. 1993; Fig. 
1 ), and the Midwinter Survey, encompassing 
the United States and portions of Canada and 



Out Living Resoun <-\ limls 






Mexico at regular intervals. Results from these 
surveys are the basis for this article. 

The Breeding Population and Habitat 
Survey is conducted during May and June when 
most species occupy their breeding ranges. 
Pilot-biologists and observers in airplanes iden- 
tify and count ducks on a sample of transects. 
Not all ducks are visible from the air, so some 
transects are resurveyed more thoroughly with a 
helicopter or from the ground to obtain com- 
plete counts. These data are used to correct the 
air counts and obtain unbiased estimates of 
duck densities in these areas. Estimates of num- 
ber of pairs of ducks are expanded to provide 
population estimates for the entire surveyed 
area. This survey, conducted by the Canadian 
Wildlife Service and the U.S. Fish and Wildlife 
Service (USFWS), is among the most extensive 
and comprehensive surveys conducted annually 
for any group of animals anywhere in the world. 
Survey estimates are the major determinant 
governing the regulation-setting process for the 
sport harvesting of ducks by both Canadian and 
United States provincial, state, and federal gov- 
ernments. 

The Breeding Population and Habitat 
Survey is most reliable for mallards (Anas 
platyrhynchos), gadwall (A. strepera), 
American wigeon (A. americana), green- 
winged teal (A. crecca), blue-winged teal {A. 
discors), northern shoveler (A. clypeata), red- 
head (Aythya americana), canvasback (A. val- 
isineria), and scaup (A. affinis and A. marila). 
Researchers and managers are trying to expand 
the geographic range of this survey in the 
Pacific Flyway, eastern Canada, and the north- 
western United States. 

The breeding survey, however, poorly moni- 
tors species such as whistling ducks 
(Dendrocygna spp.), mottled ducks (Anas ful- 
vigula), American black ducks (A. rubripes), 
most sea ducks and mergansers (Lophodytes 
cucullatus, Mergus merganser, M. serrator), 
and wood ducks (Aix sponsa). 

The Midwinter Survey has been conducted 
annually in early January since the mid-1940's. 
It is not as reliable as the breeding survey 
because of methodological shortcomings and 
because winter is a poor time to survey popula- 
tion abundance (Eggeman and Johnson 1989). 
Despite its limitations, this survey does provide 
useful information on such species as the black 
duck that are not well surveyed by the breeding 
survey (Conroy et al. 1988). 

Status and Trends 

Population estimates of all ducks from the 
breeding survey have varied from 26.5 to 42.8 
million since 1955 (Fig. 2). Generally, breeding 
populations were high in the 1950's and 70's 



and low in the 60's, 80s, and 90's. The 1993 

estimate of 28.0 million was 2095 below the 
1955-92 average. 

Estimates of ducks from the Midwinter 
Survey also have varied since 1955 (Fig. 2). The 
1993 estimate of 10.3 million ducks was the 
lowest recorded, and 44% below the 1955-92 
average. 

The Breeding Population and Habitat 
Survey provides reliable estimates for seven 
species of dabbling ducks, while the Midwinter 
Survey provides estimates for eight. The breed- 
ing population of total dabbling ducks in 1993 
was 20% below the 1955-92 average. 
Compared with the 1955-92 average, 1993 
breeding population estimates suggest popula- 
tion declines for mallards, American wigeon, 
blue-winged teal, and northern pintail. 
Population estimates were unchanged for 
green-winged teal and increased for gadwall 
and northern shoveler (Figs. 3-5). During the 
most recent 10-year period, the breeding popu- 
lation of northern pintail decreased, gadwall 
populations increased, and populations of six 
other species were stable (Table). Midwinter 
estimates of all species of dabbling ducks were 
stable or increased during 1984-93 (Table). 

Midwinter estimates are the only long-term 
data available for black ducks. Apparent differ- 
ences in population trends between the breeding 
and midwinter surveys (Table) are a function of 
differences in the quality of the surveys and in 
the populations monitored by the surveys. For 
example, breeding mallards have increased in 
recent years in the Atlantic Flyway, which is 
outside the breeding survey area. The breeding 
survey indicates a stable trend for mallards 
while the winter survey indicates an increasing 
trend; the two surveys monitor different portions 
of the total continental population. 

Five species of diving ducks are monitored 
by breeding and winter surveys. Because lesser 
scaup are not distinguished from greater scaup 
in the surveys, these species have been com- 
bined. Breeding populations of diving ducks in 
1993 were 18% below the 1955-92 average. 
Redhead and scaup breeding populations were 
lower than average, whereas the canvasback 
population was near average, ami the ring- 
necked duck (Aythya collaris) population was 
above average (Figs. 4, 6). From 1984 to 1993, 
the breeding population of scaup declined while 
the breeding population of ring-necked thicks 
increased (Table). The Midwinter Survej also 
indicated an increasing population of ring- 
necks during this period (Table). 

Fourteen species of sea clucks, mergansers. 
and their allies were monitored b> the breeding 
survey. These 14 species plus the harlequin 
duck (Histrionicus histrionicus) were moni- 
tored during the Midwinter Survey. Because 




54 57 60 63 66 69 72 75 78 81 84 87 90 93 
Year 

Fig. 2. Duck populations in North 
America, 1955-93, from the 
Breeding Population and Habitat 
Survey ami the Midwinter Survej 




Northern pintail 

Green-winged teal 

°~~ — r rT ^ 

54 57 60 63 66 69 72 75 78 81 84 87 90 93 
Year 

Fig. 3. Mallard, northern pintail, 
and green-winged teal breeding 
population estimates, 1955-93. 






54 57 606366 6972 7578 8184 8790 9: 
Year 

Fig. 4. Scaup, blue-winged teal, 
and gadwall breeding population 
estimates, 1955-93 




1 1 f 

54 57 60 6366 69 72 75 78 8184 87 90 93 
Year 

Fig. 5. \mc-ik .in M igeOD and 

northern shovela breeding popula 
tion estimates, 195 



36 



Birds — Our Living Resources 



Table. Estimated annual numbers 
(in thousands) and recent trends 
(1984-93) of ducks based on the 
survey areas monitored by breed- 
ing and midwinter surveys. 



1.0 



Redhead. 




°-° I " I ' T T ' r T T T T ' r ' I" r T ' I 
54 57 60 63 66 69 72 75 78 81 84 87 90 93 
Year 

Fig. 6. Redhead and canvasback 
breeding population estimates, 
1955-93 



Tribe and species 


Breeding 


Wintering 


No. 


Trend 


No. 


Trend 


Perching ducks 


Wood duck 






33 


Stable 


Dabbling ducks 


American black duck 






278 


Stable 


American wigeon 


2,053 


Stable 


1,088 


Stable 


Blue-winged teal 


3,192 


Stable 






Blue-winged and 
cinnamon teal 






166 


Increasing 


Gadwall 


1,755 


Increasing 


1,168 


Increasing 


Green-winged teal 


1,694 


Stable 


2,086 


Increasing 


Mallard 


5,708 


Stable 


4,994 


Increasing 


Mottled duck 






129 


Increasing 


Northern pintail 


2,053 


Decreasing 


2,241 


Stable 


Northern shoveler 


2,046 


Stable 


638 


Stable 


Diving ducks 


Canvasback 


472 


Stable 


298 


Stable 


Greater and lesser 
scaup 


4,080 


Decreasing 


1,070 


Stable 


Redhead 


485 


Stable 


336 


Stable 


Ring-necked duck 


868 


Increasing 


421 


Increasing 


Sea ducks and mergansers 


Bufflehead 


869 


Increasing 


126 


Increasing 


Eiders 3 


8 


Decreasing 


132 


Stable 


Goldeneye 13 


592 


Stable 


122 


Stable 


Harlequin duck 






<1 


Stable 


Mergansers 


528 


Stable 


264 


Increasing 


Oldsquaw 


174 


Decreasing 


10 


Decreasing 


Scoters d 


1,006 


Decreasing 


160 


Stable 


Stifftails 


Ruddy duck 


387 


Stable 


110 


Decreasing 



a Eiders include common eider (Somateria mollissima), king eider (S. 
spectabilis), spectacled eider (S. fischeri), and Steller's eider (Polysticta 
stelleri). 

b Goldeneye include Barrow's goldeneye (Bucephala islandica) and com- 
mon goldeneye [B. clangula). 

c Mergansers include hooded merganser (Laphodyies cucallatus), red- 
breasted merganser (Mergus serrala), and common merganser (M. mer- 
ganser). 

d Scoters include black scoter (Melanitta nigra), surf scoter (M. 
perspcillata), and white-winged scoter (M. fusca). 

some of these species are difficult to identify 
during aerial surveys, or are encountered rarely, 
they are combined with related species (see 
Table). 

Collectively, breeding populations of mer- 
gansers and their allies were 9% lower in 1993 
compared to the 1955-92 average. Merganser, 
oldsquaw (Clangula hyemalis), eider, and scot- 
er breeding populations in 1993 were all lower 
than their 1955-92 averages (see Table for 
species). The breeding population of goldeneye 
in 1993 was similar to the 1955-92 average, 
whereas the bufflehead (Bucephala albeola) 
breeding population was higher than the long- 
term average. During the last 10 years, breeding 
populations of eiders, oldsquaw, and scoters 
decreased, bufflehead increased, and goldeneye 
and mergansers were stable (Table). Winter 
population estimates during 1983-92 decreased 
for oldsquaw, increased for bufflehead and mer- 
gansers, and were stable for other species in the 
sea duck tribe (Table). 

In the United States and Canada, wood 
ducks are the only representative of the tribe 
Cairinina and ruddy ducks (Oxyura jamaicen- 
sis) are the only representative of the Oxyurini 



tribe. Wood ducks are hard to survey because 
they inhabit forested wetlands where it is diffi- 
cult to obtain reliable counts. Their current pop- 
ulation, however, is greater than in the early 
1900's (Bellrose 1980). Midwinter counts of 
wood ducks during 1983-92 indicated a stable 
population (Table). Ruddy duck breeding popu- 
lations in 1993 were similar to the 1955-92 
average. 

Factors Affecting Population 
Status 

Duck population changes occur on breeding, 
staging, and wintering habitats, with the 
changes on breeding habitats having the great- 
est effect on populations. Degradation and 
destruction of wetlands over the last 200 years 
have diminished duck populations; wetland 
alteration and degradation continue. The rate of 
wetland loss has been greatest in prime agricul- 
tural areas such as the Prairie Pothole region 
(Fig. 1), and lowest in northern boreal forests 
and tundra. Thus, species such as dabbling 
ducks that mostly nest in the severely altered 
Prairie Potholes have been harmed more than 
species like sea ducks and mergansers that nest 
farther north (Bellrose 1980; Johnson and Grier 
1988). 

Because most dabbling ducks need grassy 
cover for nesting (Kaminski and Weller 1992), 
conversion of native grasslands to agricultural 
production, including pastures, has reduced 
available nesting cover and contributed to a 
reduced nesting success for dabblers. This con- 
dition is especially true in the Prairie Pothole 
region of the United States and Canada (Fig. 1). 
In addition, highly variable precipitation in the 
Prairie Potholes has changed the number of 
wetlands available for nesting. For example, in 
1979 there were 6.3 million wetlands in the sur- 
veyed portion of the Prairie Pothole region, but 
by the next spring, wetlands in the same area 
had decreased 55% to 2.9 million. Two years 
later they increased more than 100% to 4.2 mil- 
lion. These annual changes can temporarily 
mask the long-term declining trend in wetland 
abundance across the Prairie Pothole region. 

The changing availability of wetland habi- 
tats in the Prairie Potholes region causes sub- 
stantial fluctuations in some duck populations. 
During periods of high precipitation, larger wet- 
land basins are full or overflowing, and shallow 
wetlands are abundant. Species such as the 
northern pintail, which tend to use shallow or 
ephemeral wetlands for feeding, produce more 
young when wetland numbers increase (Smith 
1970; Hochbaum and Bossenmaier 1972). 
Consequently, population numbers increase as 
they did during the 1970's. 



Our Living Resources Hint\ 



.17 



During the driest periods, however, such as 
those in the 1980's, only the deepest and most 
permanent wetlands retain water, causing popu- 
lation declines in species such as pintails that 
rely primarily on shallow wetlands. Population 
numbers are more stable for species like the 
canvasback, which rely on deeper marshes, and 
are therefore less affected by annual changes in 
wetland numbers because deeper marshes con- 
sistently retain water, providing ample habitat 
in most years (Stewart and Kantrud 1973). 

Nest success in the Prairie Pothole region 
has declined in recent years largely because of 
increased nest predation caused by the range 
expansion of some predators and by reduced 
nesting habitat (Sargeant and Raveling 1992). 
Fewer and smaller areas of nesting habitat con- 
centrate duck nests, enhancing the ability of 
predators to find nests. Predators such as rac- 
coons (Procyon lotor) have expanded their 
range northward, probably because they can 
den in buildings, rock piles, and other human- 
made sites during winter. 

Although wetland drainage, urbanization, 
and other human-caused changes have resulted 
in wintering habitat losses, these losses have 
been offset, at least for dabbling ducks, by 
increased fall and winter food from waste grain 
left in stubble fields. In addition, the national 
wildlife refuge system has protected and man- 
aged many staging and wintering areas for the 
benefit of waterfowl. 

Modern duck-hunting regulations are 
believed to keep recreational harvest at levels 
compatible with the long-term welfare of duck 
populations. The proportion of ducks harvested 
varies regionally and by species, age, and sex. 
In 1992, 2%-12% of the adult mallards from the 
Prairie Pothole region were killed by hunters. 
Harvest rates of other species were generally 
lower. These conservative harvest rates are 
unlikely to cause population declines (Blohm 
1989). 

Conclusions 

Changes in duck populations reflect changes 
in quality and quantity of waterfowl habitats. 
Long-term declines in populations have been 
caused by extensive habitat alterations. By con- 
trast, short-term changes primarily reflect 
weather and resultant availability of wetland 
habitats. Maintenance of the current monitoring 
system and initiatives to improve our monitor- 
ing capability are essential for effective duck 



management. 

Maintaining or increasing the quality and 
quantity of waterfowl habitat is needed to stabi- 
lize or increase duck populations. Agricultural 
policies and practices can profoundly affect 
habitat availability in Canada and the United 
States. For example, the Conservation Reserve 
Program, in which certain agricultural areas 
were set aside and planted in grasses, has added 
much-needed dabbling duck nesting habitat and 
therefore has improved their productivity in the 
U.S. portion of the Prairie Pothole region (R.E. 
Reynolds, USFWS, personal communication). 
The North American Waterfowl Management 
Plan, through its regional joint ventures, is striv- 
ing to increase the habitat available for water- 
fowl and to improve monitoring of some popu- 
lations. 

References 

Bellrose, F.C. 1980. Ducks, geese and swans of North 
America. 3rd ed. Stackpole Books. Harrisburg, PA. 540 
pp. 

Blohm. R.J. 1989. Introduction to harvest: understanding 
surveys and season setting. Pages 118-129 in K.H. 
Beattie, ed. Sixth International Waterfowl Symposium. 
Washington, DC. 

Caithamer, D.F, J. A. Dubovsky, F.A. Johnson. J.R. Kelley, 
Jr.. and G.W. Smith. 1993. Waterfowl: status and fall 
flight forecast. Administrative Rep., U.S. Fish and 
Wildlife Service, Washington. DC. 37 pp. 

Conroy M.J., J.R. Goldsberry. J.E. Hines. and D.B. Sums. 
1988. Evaluation of aerial transect surveys for wintering 
American black ducks. Journal of Wildlife Management 
52:694-703. 

Eggeman, D.R.. and F.A. Johnson. 1989. Variation in effort 
and methodology for the midwinter waterfowl inventory 
in the Atlantic Flyway. Wildlife Society Bull. 17:227- 
233. 

Hochbaum, G.S.. and E.F. Bossenmaier. 1972. Response of 
pintail to improved breeding habitat in southern 
Manitoba. Canadian Field-Naturalist 86:79-81. 

Johnson. D.H.. and J.W. Grier. 1988. Determinants o\ 
breeding distributions of ducks. Wildlife Monograph 
100:1-37. 

Kaminski. R.M., and M.W. Welter. 1992. Breeding habitats 
of nearctic waterfowl. Pages 568-589 in B.J. Batt, A.D. 
Afton, M.G. Anderson. CD. Ankney. D.H. Johnson. J. A. 
Kadlec, and G.L. Krapu. eds. Ecology and management 
of breeding waterfowl. University of Minnesota Press. 
Minneapolis. 

Sargeant. A.B.. and D.G. Raveling. 1992. Mortality during 
the breeding season. Pages 396-422 in B.J. Batt, A.I) 
Afton. M.G. Anderson. CD. Ankney. D.H. Johnson. IV 
Kadlec, and G.L. Krapu, eds. Ecology and management 
of breeding waterfowl. Universitj of Minnesota Press. 
Minneapolis. 

Smith, R.I. 1970. Response ol pintail breeding populations 
to drought. Journal of Wildlife Management 34:943 946 

Stewart, R.E., and H.A. Kantrud. 1973. Ecological distribu- 
tion of breeding waterfowl populations in North Dakota 
Journal ol Wildlife Management 37:39-50. 



For further Information: 

Da\ id l ( 'aithamei 

U.S. Fish and Wildlife Service 

Office oi Migrator) Bud 

Management 

llensii.iu l Aborator) 

I I50(i American Holl) Di 

l aurel, MD 20708 



38 



Birds — Our Living Rtsourcts 



Decline of 

Northern 

Pintails 



by 

Jay B. Hestback 

National Biological Service 



Fig. 1. Number of pintails in 
northern areas from Alaska to 
northern Alberta and northern 
Manitoba and in the prairie region 
from southern Alberta and central 
Montana to southern Manitoba 
and the Dakotas from 1955 to 
1993 (Breeding Population and 
Habitat Survey, U.S. Fish and 
Wildlife Service. Office of 
Migratory Bird Management). 



The size of the continental breeding popula- 
tion of northern pintail (Anas acuta) has 
greatly varied since 1955, with numbers in sur- 
veyed areas ranging from a high of 9.9 million 
in 1956 to a low of 1.8 million in 1991. This 
variation results primarily from differences in 
the numbers of breeding pintails in the prairie 
region of Canada and the United States (Fig. 1); 
these numbers ranged from 8.6 million in 1956 
to 0.5 million in 1991; numbers in the northern 
regions from Alaska to northern Alberta and 
northern Manitoba varied primarily between 1 
and 2 million. 

Breeding pintails prefer seasonal shallow- 
water habitats without tall emergent aquatic 
vegetation (Smith 1968). The proportions and 
distribution of breeding pintails on the prairies 
vary annually depending on the amount of 
annual precipitation and the resulting increase 
or decrease in the availability of suitable breed- 
ing habitat (Smith 1970; Johnson and Grier 
1988). 

Changes in the size of the continental pintail 
population result from changes in production, 
survival, or both. Consequently, understanding 
population changes involves detecting variation 
in survival and production over time and relat- 
ing that variation to changes in population size. 
Once the cause of the decline is determined, 
appropriate management strategies can be 
developed to reverse it. 




54 57 60 63 66 69 72 75 78 81 84 87 90 93 
Year 



Status and Trends 

I arbitrarily partitioned the population data 
into periods of relative growth, stability, and 
decline to help explain changes in the continen- 
tal breeding population, which declined from 
1955 to 1962, increased from 1963 to 1970. 
remained at a high stable level from 1971 to 
1979, and declined from 1980 to 1992. I also 
partitioned the continental population into fly- 
ways based on data from recoveries of winter- 
banded pintails. This data indicated that pintails 
exhibit a high fidelity to the winter-banding 
region and fly way (Hestbeck 1993). Data from 
recoveries of summer-banded pintails were 
used to associate birds between breeding and 




Pintails (Anas acuta 



wintering areas. 

Data on the pintail population were obtained 
through various surveys conducted by the 
United States and Canada. The Breeding 
Population and Habitat Survey provided esti- 
mates for the number of breeding pintails and 
for the total number of ponds. The total number 
of ponds was used as an index of breeding-habi- 
tat availability where the availability increased 
as the number of ponds increased. Annual sur- 
vival rates were estimated from legband recov- 
eries of summer-banded pintails. 

I estimated average survival rates for the pre- 
viously listed time periods for all areas with 
banding data. As an index of production, I used 
the number of young females divided by the 
number of adult females (i.e., age-ratio) har- 
vested annually in each flyway reported in the 
Waterfowl Parts Collection Survey (U.S. Fish 
and Wildlife Service, Office of Migratory Bird 
Management). Because of possible harvest dif- 
ferences among flyways and large variation in 
annual ratios, I estimated the average age-ratio 
for each flyway for the above time periods. 

Changes in the continental population can be 
addressed by studying changes in flyway popu- 
lations because pintails from different summer 
breeding areas were associated with certain 
wintering areas. Generally, pintails wintering in 
the Pacific Flyway were associated with breed- 
ing areas in the western states and provinces 
from Alaska to Saskatchewan and central 
Montana. Pintails in the Central Flyway were 
primarily associated with breeding areas in 
Saskatchewan, eastern Montana, Manitoba, and 
the Dakotas. Pintails in the Mississippi Flyway 
were primarily associated with breeding areas 
from Saskatchewan and Minnesota to James 
Bay. Pintails in the Atlantic Flyway were pri- 
marily associated with breeding areas from 
James Bay to the Canadian Maritimes. 

If 1980-92 population declines were caused 
by poor reproduction, production would be 
lower. Production, however, remained relatively 
constant over periods of population growth 
(1963-70), stability (1971-79), and decline 



Oiu Living Resources Birds 



39 



(1980-92) for the Atlantic, Mississippi, and 
Central flyways (Fig. 2). Production in the 
Pacific Flyway exhibited a substantial decline 
from 2.40 in 1963-70, to 1.78 in 1971-79, and to 
1.60 in 1980-92. 

Likewise, survival would be lower during 
1980-92 if population declines were caused by 
declines in survival. Comparisons of average 
survival rates between 1980-92 and earlier peri- 
ods were possible for only a limited number of 
areas because few pintails were banded in many 
regions. In the area encompassing northern 
Alberta, northeastern British Columbia, and 
southwestern Northwest Territories, average 
survival during 1980-92 was higher than the 
average for earlier periods for adult males (80% 
versus 68%), young males (68% versus 53%), 
and adult females (69% versus 64%). In south- 
ern Alberta, average survival during 1980-92 
was higher than the average for earlier periods 
for adult males (74% versus 70%) and young 
females (86% versus 55%). Survival remained 
constant between 1980-92 and earlier periods 
for all age-classes of pintails banded in southern 
Saskatchewan and southern Manitoba. In the 
Dakotas, average survival during 1980-92 was 
higher for only adult males (77% versus 66%). 

These data reveal that possible declines in 
pintail survival did not cause the population 
declines observed during the 1980's. Overall, 
survival was higher during 1980-92 than during 
earlier periods for adult males that winter in the 
Pacific, Central, and Mississippi flyways and 
for young females that winter in the Pacific 
Flyway. Survival remained constant between 
time periods for adult females and young males 
in the Pacific, Central, and Mississippi flyways. 

Given the small changes in production and 
survival, pintail numbers should stabilize in the 
Central and Mississippi flyways and possibly 
the Atlantic Flyway. In the Pacific Flyway, how- 
ever, the survival increases of young females 
has not compensated for the overall decrease in 
production. 

During the 1980's the Canadian prairies on 
the average received less precipitation, resulting 
in reduced availability of pintail breeding habi- 
tat. Hopes for increased pintail population size 
have been based, in part, on the expectation that 
increased precipitation in the western Canadian 
prairies would result in increased breeding habi- 
tat and production. Female-based age-ratio data 
suggest, though, that increased production is 
unlikely to occur even with increased precipita- 
tion because pintail production remained low 
even when water was plentiful. Average age- 
ratios for the Pacific Flyway when water in the 
western Canadian prairies was above average 
(total May ponds for southern Alberta and 



Atlantic 



Mississippi 



Central 



Pacific 



°- 1.0 




1963-70 



1971-79 
Year 



1980-92 



southern Saskatchewan exceeding 2.68 million) 
steadily declined from 3.11 in the 196()'s. to 
2.03 in the 1970's, and 1.86 in the 1980's. 

Consequently, a fundamental change 
appears to have occurred in pintail productivity 
on western Canadian prairies, meaning that we 
cannot base pintail management on the hope 
that increased precipitation will result in a 
return to the higher levels of production experi- 
enced in the 1960's. 

Researchers suspect that the production 
decline may be related to the fact that the shal- 
low-water breeding habitat favored by pintails 
is most susceptible to agricultural drainage. By 
1989, 78% of the pothole margins (the transi- 
tion zone where potholes meet farmland) and 
22% of wet basins were degraded by agricultur- 
al activity in prairie Canada (FD. Caswell and 
A. Didiuk, Canadian Wildlife Service, personal 
communication). Increased intensification of 
agriculture may also contribute to lower pro- 
duction on the prairies through increased graz- 
ing and cropping, increased nest destruction, 
and increased use of agricultural chemicals 
(Ducks Unlimited 1990). Further research on 
the western Canadian prairies is necessary to 
determine specific causes of production 
declines in pintails and to determine methods to 
increase production. 

References 

Ducks Unlimited. 1990. Sprig: population recovers strategy 
for the northern pintail. Ducks Unlimited, Inc., Long 
Grove, IL. 30 pp. 

Hestbeck. J.B. 1993. Overwinter distribution of northern 
pintail populations in North America. Journal of w ildlife 
Management 57:582-589. 

Johnson. D.H., and J.W. Grier. I''** Determinants of 
breeding distributions oi thicks. Wildlife Monograph 
100. 37 pp. 

Smith. R.I. 1968. The social aspects of reproductive behav- 
ior in the pintail. Auk 85:38 1 196 

Smith. R.I. 1970. Response of pmtaii breeding populations 
to drought. Journal of Wildlife Management 34:943 946 



Fig. 2. Average production of pin- 
tails in Atlantic. Mississippi. 

Central, and Pacific flyways tor 
1963-70, 1971-79. and 1980-92 
(Waterfowl Pans Collection 
Survey, U.S. Fish and Wildlife 
Service, Office of Migrators Bird 
Management) 



lor hither Information: 

la) B Hestbeck 

Nation. ii Biological Service 

Cooperative Fish and Wildlife 

Research Unit 

Universit) of Massachusetts 

Amherst, MA 01003 



40 



Birds — Our Living Resources 



Canvasback 
Ducks 

by 

William L. Hohman 

G. Michael Haramis 

Dennis G. Jorde 

Carl E. Korschgen 

John Takekawa 

National Biological Service 



Canvasbacks (Aythya valisineria) are unique 
to North America and are one of our most 
widely recognized waterfowl species. Unlike 
other ducks that nest and feed in uplands, diving 
ducks such as canvasbacks are totally dependent 
on aquatic habitats throughout their life cycle. 
Canvasbacks nest in prairie, parkland, subarctic, 
and Great Basin wetlands; stage during spring 
and fall on prairie marshes, northern lakes, and 
rivers; and winter in Atlantic, Pacific, and Gulf 
of Mexico bays, estuaries, and some inland 
lakes. They feed on plant and animal foods in 
wetland sediments. Availability of preferred 
foods, especially energy-rich subterranean plant 
parts, is probably the most important factor 
influencing geographic distribution and habitat 
use by canvasbacks. 

In spite of management efforts that have 
included restrictive harvest regulations and fre- 
quent hunting closures in all or some of the fly- 
ways (Anderson 1989), canvasback numbers 
declined from 1955 to 1993 and remain below 
the population goal (540,000) of the North 
American Waterfowl Management Plan 
(USFWS and Canadian Wildlife Service 1994). 
Causes for this apparent decline are not well 
understood, but habitat loss and degradation, low 
rates of recruitment, a highly skewed sex ratio 
favoring males, and reduced survival of canvas- 
backs during their first year are considered 
important constraints on population growth. 



Population size = 620,540 - 2,873 (year) 
r 2 = 0.11. P= 0.014 



I I I | I 
55 58 



TTT 
64 



67 



I I I I I 

70 73 

Year 



TTTT 

76 79 



82 



85 



91 93 



Figure. Estimated breeding popu- 
lation of canvasbacks, 1955-93 
(data from the U.S. Fish and 
Wildlife Service, Office of 
Migratory Bird Management). 



Status and Trends 

Canvasback population trends are monitored 
by means of annual Breeding Waterfowl and 
Habitat Surveys and Midwinter Waterfowl 
Inventories (MWI). Readers should refer to 
cited literature for additional information 
regarding methods. 

Canvasback Numbers and Distribution 

Between 1955 and 1993 population indices 
for canvasbacks fluctuated between 353,700 
and 742,400 and averaged 534,000 ducks 



(Figure). The population showed a general rate 
of decline of 0.6% per year during the period; 
however, because population estimates are 
imprecise, annual differences are difficult to 
detect. For example, a population change of 
more than 30% would be needed to detect a sig- 
nificant difference between years with 90% 
confidence. 

The winter distribution of canvasbacks has 
changed since the 1950's. when most canvas- 
backs (79%) were found wintering in the 
Atlantic or Pacific flyways. The proportion of 
the continental population wintering in the 
Central and Mississippi flyways increased from 
21% in 1955-69 to 44% in 1987-92 as a result 
of declines in canvasback numbers at 
Chesapeake Bay and San Francisco Bay and 
increases in the Gulf of Mexico region. Only 
about 23,000 canvasbacks winter in Mexico, but 
numbers may be increasing (Office of 
Migratory Bird Management, unpublished 
data). Shifts in winter distribution probably 
reflect regional differences in habitat availabili- 
ty, but may also indicate differences in survival 
and recruitment. 

Sex Ratios 

Canvasbacks have a highly skewed sex ratio 
favoring males. Sex ratios of wintering canvas- 
backs in Louisiana (1.6-1.8 males:female; 
Woolington 1993) and San Francisco Bay (2.2 
males:female; J. Takekawa, unpublished data) 
are lower than those observed in the Atlantic 
Flyway (2.9-3.2 malesTemale), but sex ratios 
apparently decreased in two mid- Atlantic states 
between 1981 and 1987 (Haramis et al. 1985, 
1 994). Based on recent ( 1 987-92) MWI and sex 
ratio data, we calculated that the continental sex 
ratio for canvasbacks likely lies between 2.0 
and 2.5 males: female. 

Survival 

Annual survival rates of female canvasbacks 
(56%-69%) are lower than those of males 
(70%-82%; Nichols and Haramis 1980). 
Survival rates also vary geographically (survival 
is greater in the Pacific Flyway than in the 
Atlantic; Nichols and Haramis 1980) and are 
positively related to body mass in early winter 
(Haramis et al. 1986). Survival of females in 
their first year probably is reduced relative to 
that of adults. Assuming that all surviving 
females return to their natal areas to breed, 
return rates for female canvasbacks breeding in 
southwestern Manitoba suggest that only 21% 
of hens survive their first year compared to 69% 
annual survival of older hens (Serie et al. 1992). 

Nichols and Haramis ( 1980) found no asso- 
ciation between canvasback harvest regulations 
and survival. However, an analysis of return 



Our living Resoun es IUnl\ 



41 



rates for female canvasbacks in southwestern 
Manitoba indicated that survival of immatures 
was significantly related to harvest (M.G. 
Anderson, Ducks Unlimited-Canada, unpub- 
lished data). The canvasback season was closed 
in the Atlantic, Central, and Mississippi flyways 
during 1986-93. but about 8,000 birds were har- 
vested annually in Canada and 10,000 in the 
Pacific Flyway. There is also a substantial ille- 
gal harvest of canvasbacks at some sites 
(Haramis et al. 1993; Korschgen et al. 1993; 
W.L. Hohman, unpublished data). However, the 
current level of hunting-related mortality is 
probably not limiting population growth. 
Rather, annual variation in recruitment and 
degradation and loss of breeding, migrational, 
and wintering habitats are more likely influenc- 
ing population size. 

Time-specific Survival Rates and Sources of 
Mortality 

Survival rates for adults in spring and sum- 
mer are unknown. In spite of a nationwide ban 
on the use of lead shot by waterfowl hunters, 
ingestion of spent lead shotgun pellets by water- 
fowl is common and likely will remain so for 
many years. More than 50% of spring-migrat- 
ing canvasbacks captured at a major staging 
area on the Mississippi River had elevated 
blood lead levels (Havera et al. 1992). Lead- 
exposed birds have reduced body mass, fat, and 
protein (Hohman et al. 1990), so their subse- 
quent survival and ability to reproduce and per- 
form activities such as courtship, migration, or 
molt, may be compromised. 

Nest success (i.e., embryonic survival) of 
canvasbacks is highly variable, especially for 
birds nesting on the prairies. For example, nest 
success in southwestern Manitoba in wet years 
was 54%-60%, but in dry years averaged only 
17% (Serie et al. 1992). In spite of habitat loss 
and degradation, ranges in nest success 
observed in southwestern Manitoba were simi- 
lar in 1961-72 (21%-62%; Stoudt 1982) and 
1974-80 (17%-60%; Serie et al. 1992). 
Mammalian predation, especially by mink 
(Mustela vison) and raccoon (Procyon lotor), is 
an important factor affecting the nest success of 
prairie-nesting canvasbacks. 

Mortality of prefledged ducklings is high, 
especially during the first 10 days (C.E. 
Korschgen, unpublished data). In northwestern 
Minnesota, estimated survival rates for duck- 
lings up to 10 days old ranged from near zero to 
70%, but differed between sexes during the first 
25 days of life (male > female; C.E. Korschgen, 
unpublished data). Predation and weather were 
the primary sources of duckling mortality. 
Survival of young between fledging and fall 
migration is unknown; however, production 
estimates calculated from harvest information 




(0.16-1.07 young:adult) suggest that recruit- 
ment rates for canvasbacks generally are low 
compared to other ducks. 

Survival rates for fall-migrating canvasbacks 
have not been studied, but survival rates have 
been estimated at several major wintering sites. 
Adult and immature females had high winter 
survival at Chesapeake Bay (83%- 100%; 
Haramis et al. 1993) and coastal Louisiana (> 
95%; Hohman et al. 1993). Winter survival was 
lower at Catahoula Lake, Louisiana (57%- 
92%), where canvasbacks were not only shot 
illegally but where substantial numbers of birds 
were also exposed to lead (W.L. Hohman, 
unpublished data). 

Habitat Trends 

Historically, climate, grazing, and fire were 
major factors affecting habitats of prairie-nest- 
ing waterfowl. Since settlement, however, 
human activities, especially those related to 
agriculture, have had a major impact on the 
quantity and quality of breeding habitats. 
Nationwide, over 53% of original wetlands 
have been lost. Wetland losses in states where 
canvasbacks historically nested range from less 
than 1% (Alaska) to 89% (Iowa); however, 
deeper wetlands preferred by nesting canvas- 
backs probably have been drained to a lesser 
extent than shallower wetlands. 

Northern lakes used by canvasbacks for 
molting and staging before fall migration prob- 
ably have been least affected by human and nat- 
ural perturbations. Nonetheless, disturbances 
related to commercial and recreational activi- 
ties, nutrient enrichment of lakes resulting from 
sewage discharges and agricultural runoff, 
introductions of herbivorous fish, and alteration 
of lake levels for generation of hydroelectric 
power have reduced the suitability and use ol 
some traditional sta-jin;.' areas in the southern 
boreal forest region. 



Canvasback (Aythya rati sine rut). 



42 



Birds — Our Living Resources 



Most of the traditional stopover habitats used 
by migrating canvasbacks no longer provide 
suitable feeding and resting opportunities (Kahl 
1 99 1 ). For example, of the more than 40 former 
migration stopover areas in the upper portion of 
the Mississippi Flyway, only Lake Christina in 
west-central Minnesota, two pools on the Upper 
Mississippi River, and two areas on the Great 
Lakes have peak populations of more than 5,000 
canvasbacks (Korschgen 1989). Restoration 
efforts begun in 1987 at Lake Christina were 
successful in reestablishing submersed aquatic 
vegetation and canvasback use. Habitat on the 
Upper Mississippi River increased in extent 
from the mid-1960's to the late 1980's. 
However, record drought in 1988-89 and exten- 
sive flooding in 1993 in the Upper Mississippi 
River basin have caused major declines in habi- 
tat quality and abundance. 

In the Great Lakes region, increased bird use 
of Lake St. Clair and Long Point on Lake Erie 
coincided with improved water quality and 
increased production of submersed aquatic 
plants, especially wildcelery (Vallisneria aineri- 
cana). These improvements are attributed to 
regulation of water discharges into the Great 
Lakes and perhaps the proliferation of zebra 
mussels (Dreissena polymorpha). 

In the Pacific Flyway, coastal habitats used 
by migrating canvasbacks have not changed 
greatly since the 1950's, although development 
has increased in some areas (e.g., Puget Sound). 
Whereas use of some inland sites (e.g., Great 
Salt Lake, Utah; Malheur National Wildlife 
Refuge (NWR), Oregon; and Stillwater NWR, 
Nevada) declined during the 1970's or 1980's, 
canvasback use of Klamath Basin NWR, 
Oregon-California, and Pyramid Lake, Nevada, 
has increased. 

Degradation of water quality in the 
Chesapeake Bay caused by nutrient enrichment, 
turbidity, and sedimentation reduced the abun- 
dance of aquatic plant and animal foods most 
important to canvasbacks in winter (Haramis 
1991). Declining availability of plant foods 
caused canvasbacks to shift to mostly animal 
foods. Canvasback numbers declined in 
response to loss of aquatic plants in the 
Chesapeake Bay, but increased in North 
Carolina and Virginia where preferred plant 
foods were still abundant (Lovvorn 1989). 
Aquatic plants are now declining in the coastal 
areas of North Carolina and other wintering 
areas throughout the Atlantic Flyway. Unless 
the widespread decline of aquatic plant foods is 
reversed, the number of canvasbacks wintering 
in the Atlantic Flyway is not likely to increase. 

San Francisco Bay is the most important 
wintering area for canvasbacks in the Pacific 
Flyway. Urban development there has greatly 
reduced available habitat. In remaining habi- 



tats, canvasbacks are exposed to high levels of 
environmental contaminants (Miles and 
Ohlendorf 1993). Canvasbacks make extensive 
use of salt evaporation ponds in northern San 
Francisco Bay (Accurso 1992). These ponds 
recently came under public ownership, but their 
management as tidal salt marshes will probably 
reduce their use by canvasbacks. Increasing 
numbers of canvasbacks have been observed 
recently on wetland easements and sewage 
lagoons in the northern San Joaquin Valley. 

Increased numbers of canvasbacks are win- 
tering in the Gulf of Mexico region, especially 
at Catahoula Lake, where, since 1985, peak 
numbers (up to 78,000 birds) have equaled or 
exceeded counts on traditional wintering areas 
such as Chesapeake Bay and San Francisco 
Bay. Birds appear to be attracted to Catahoula 
Lake because of its abundant plant foods and 
stable flooding regime (Woolington and 
Emfinger 1989). These birds are at risk of lead 
poisoning, however, because of the high density 
of spent lead shot contained in lake sediments. 

Information Gaps 

Information needs for improved manage- 
ment of canvasbacks include banding or radio- 
telemetry data sufficient to provide habitat 
information and estimates of region-specific 
rates of survival, band recovery, and recruit- 
ment; survival rates of immature birds between 
hatch and arrival on wintering areas; and cross- 
seasonal effects of winter nutrition and contam- 
inant exposure on reproduction. 

References 

Accurso, L.M. 1992. Distribution and abundance of winter- 
ing waterfowl on San Francisco Bay, 1988-1990. M.S. 
thesis. Humboldt State University. Acadia, CA. 252 pp. 

Anderson, M.G. 1989. Species closures — a case study of 
wintering waterfowl on San Francisco Bay. 1988-1990. 
M.S. thesis. Humbolt State University. Acadia. CA. 252 
pp. 

Haramis, G.M. 1991. Canvasback. Pages 17.1-17.10 in S.L. 
Funderburk. J. A. Mihursky. S.J. Jordan, and D. Riley, 
eds. Habitat requirements for Chesapeake Bay living 
resources. 2nd ed. Living Resources Subcommittee. 
Chesapeake Bay Program. Annapolis. MD. 

Haramis. G.M., E.L. Derleth. and W.A. Link. 1994. Flock 
sizes and sex ratios of canvasbacks in Chesapeake and 
North Carolina. Journal of Wildlife Management 58:123- 
130. 

Haramis, G.M.. J.R. Goldsberry. D.G. McAuley. and E.L. 
Derleth. 1985. An aerial photographic census of 
Chesapeake and North Carolina canvasbacks. Journal of 
Wildlife Management 49:449-454. 

Haramis. G.M.. D.G. Jorde. and CM. Bunck. 1993. 
Survival of hatching-year female canvasbacks wintering 
on Chesapeake Bay. Journal of Wildlife Management 
57:763-770. 

Haramis. G.M.. J.D. Nichols. K.H. Pollock, and J.E. Hines. 
1986. The relationship between body mass and survival 
of wintering canvasbacks. Auk 103:506-514. 



Our Living Resources — Birds 



43 



Havera, S.P.. R.M. Whitton, and R.T. Shealy. 1992. Blood 
lead and ingested shot in diving ducks during spring. 
Journal of Wildlife Management 56:539-545. 

Hohman, W.L., R.D. Pritchert. J.L. Moore, and DO. 
Schaeffer. 1993. Survival of female canvasbacks winter- 
ing in coastal Louisiana. Journal of Wildlife 
Management 57:758-762. 

Hohman, W.L., R.D. Pritchert, R.M. Pace, D.W. 
Woolington, and R. Helm. 1990. Influence of ingested 
lead on body mass cf wintering canvasbacks. Journal of 
Wildlife Management 54:211-215. 

Kahl, R. 1991. Restoration of canvasback migrational stag- 
ing habitat in Wisconsin. Tech. Bull. 172. Department of 
Natural Resources, Madison, WI. 47 pp. 

Korschgen, C.E. 1989. Riverine and deepwater habitats for 
diving ducks. Pages 157-189 in L.M. Smith, R.L. 
Pederson, and R.M. Kaminski, eds. Habitat management 
for migrating and wintering waterfowl in North America. 
Texas Tech University Press, Lubbock. 

Korschgen, C.E., K. Kenow, J. Nissen, and J. Wetzel. 1993. 
Final report: canvasback hunting mortality and hunter 
education efforts on the Upper Mississippi River 
National Wildlife and Fish Refuge. U.S. Fish and 
Wildlife Service, LaCrosse. WI. 50 pp. 

Lovvorn, J.R. 1989. Distributional responses of canvas- 
backs to weather and habitat change. Journal of Applied 
Ecology 26:113-130. 



Miles, A.K., and H.M. Ohlendorf. 1993, Environmental 
contaminants in canvasbacks wintering on San Francisco 

Bay, California. California Fish and Game 79:28-38. 

Nichols, J.D., and G.M. Haramis. 1980. Inferences regard- 
ing survival and recovery rates of winter-banded canvas- 
backs. Journal of Wildlife Management 4:164-173. 

Serie, J.R., D.L. Trauger, and J.E. Austin. 1992. Influence o\ 
age and selected environmental factors on reproductive 
performance of canvasbacks. Journal ot Wildlife 
Management 56:546-555. 

Stoudt. J.H. 1982. Habitat use and productivity of canvas- 
backs in southwestern Manitoba. 1961-72. U.S. Fish and 
Wildlife Service Special Sci. Rep. Wildlife 248. 31 pp. 

Woolington, D.W. 1993. Sex ratios of wintering canvas- 
backs in Louisiana. Journal of Wildlife Management 
57:751-757. 

Woolington, D.W., and J.W. Emfinger. 1989. Trends in win- 
tering canvasback populations at Catahoula Lake, 
Louisiana. Proceedings of the Annual Conference of the 
Southeastern Association of Fish and Wildlife Agencies 
43:396-403. 

USFWS and Canadian Wildlife Service. 1994. North 
American waterfowl management plan 1994 update, 
expanding the commitment. U.S. Fish and Wildlife 
Service, Washington, DC. 40 pp. 



For further information: 

William L. Hohman 

National Biological Service 

Southern Science Center 

700 Cajundome Blvd. 

Lafayette, LA 70506 



More than two million seabirds of 29 
species nest along the west coasts of 
California, Oregon, and Washington, including 
three species listed on the federal list of threat- 
ened and endangered species: the brown pelican 
(Pelecanus occidentalis), least tern (Sterna 
antillarum), and marbled murrelet 
(Brachyramphus marmoratus). The size and 
diversity of the breeding seabird community in 
this region reflect excellent nearshore prey con- 
ditions; subtropical waters within the southern 
California Bight area; complex tidal waters of 
Strait of Juan de Fuca and Puget Sound in 
Washington; large estuaries at San Francisco 
Bay, Columbia River, and Grays Harbor- 
Willapa bays; and the variety of nesting habitats 
used by seabirds throughout the region, includ- 
ing islands, mainland cliffs, old-growth forests, 
and artificial structures. 

Breeding seabird populations along the west 
coast have declined since European settlement 
began in the late 1700's because of human 
occupation of, commercial use of, and introduc- 
tion of mammalian predators to seabird nesting 
islands. In the 1900's, further declines occurred 
in association with rapid human population 
growth and intensive commercial use of natural 
resources in the Pacific region. In particular, 
severe adverse impacts have occurred from par- 
tial or complete nesting habitat destruction on 
islands or the mainland, human disturbance of 
nesting islands or areas, marine pollution, fish- 
eries, and logging of old-growth forests (Ainley 
and Lewis 1974; Bartonek and Nettleship 1979; 
Hunt et al. 1979; Sowls et al. 1980; Nettleship 
et al. 1984; Speich and Wahl 1989; Ainley and 
Boekelheide 1990; Sealy 1990; Ainley and 



Hunt 1 99 1 ; Carter and Morrison 1 992; Carter et 
al. 1992; Vermeer et al. 1993). 

Methods 

Population status of breeding seabirds on the 
west coast has been measured primarily through 
the determination of and trends in population 
size, based on counts of birds and nests at nest- 
ing colonies (e.g., Sowls et al. 1980). At-sea 
surveys also have been used to approximate 
population sizes for breeding and nonbreeding 
populations and species as well as their foraging 
distribution alongshore and offshore (e.g., 
Briggs et al. 1987). Rather than just monitoring 
small plots of nests on a few accessible islands 
to determine status and trends, relatively accu- 
rate and standardized censuses of entire coastal 
seabird breeding populations (except for certain 
nesting areas of difficult-to-census species) 
have been conducted annually or periodically to 
determine the overall status of many species 
breeding on the west coast (Figs. 1-4). 
However, we have considered census accuracy, 
natural variability, trends at well-studied 
colonies (e.g., Farallon National Wildlife 
Refuge) and many other factors in assessing 
population status and trends. 

Status and Trends 

Storm-petrels (Hydrobatidae) 

Increasing numbers of Leach's storm-petrels 

(Oceanodroma leucorhoa) have been docu- 
mented recently in Oregon (R.W. Lowe, 
USFWS, unpublished data I. although this 



Breeding 
Seabirds in 
California, 
Oregon, and 
Washington 



by 

Harry R. Carter 

David S. Gilmer 

National Biological Service 

Jean E. Takekawa 

Roy W. Lowe 

Ulrich W. Wilson 

U.S. Fish and Wildlife Service 



\ 



44 



Birds — Our Living Resources 




12- 
9- 



Brown pelican 



(1,000's) 



Leach's storm-petrel 




Double-crested cormorant 




7 — 
6 — 
5- 



2 — t ro 

^ oo o 

-•- c\j 

1 - in — r^T 

o 



Ashy storm-petrel 



(1,000's) 



Brandt's cormorant 



(10,000's) 



2- 



■ 1 





* 


CO 


ID 


CD 


1 "> 





250 
200 
150 
100 
50 



Black storm-petrel 



15 



Pelagic cormorant 



(1,000's) 



CO CO 



75-80 89-91 79 88 78-82 91 
CA OR WA 

Year 

Fig. 1. Status and trends of breed- 
ing populations of storm-petrels, 
pelicans, and cormorants on the 
west coasts of California. Oregon, 
and Washington. Data for small 
inland populations of white peli- 
cans and double-crested cor- 
morants are not included. ND — 
no data available; — no coastal 
nesting. Sources: CA (Hunt et al. 
1979; Sowls et al. 1980; Carter et 
al. 1992); OR (Varoujean and 
Pitman 1979; R.W. Lowe, unpub- 
lished data); and WA (Speich and 
Wahl 1989; U.W. Wilson, unpub- 
lished data). Also see Carter et al. 
(in press) for double-crested cor- 
morant. 



■I 





tmm 


CO 


CM 


CD 


If) 


CO 








^ 


CO 



75-80 89-91 79 88 78-82 91 

CA OR WA 

Year 



increase probably represents greater survey 
effort (Fig. 1). They have declined in northern 
California because of the loss of burrow-nesting 
habitats due to soil erosion and defoilation by 
nesting cormorants (Carter et al. 1992). Ashy 
storm-petrels (O. homochroa) have declined 
recently at the world's largest known colony at 
the South Farallon Islands, possibly because of 
high gull predation (W.J. Sydeman, Point Reyes 
Bird Observatory, unpublished data). This 
decline is of concern because the small world 
population of this species (fewer than 10,000 
breeding birds) nests entirely in California. 
Greater numbers of ashy and black storm- 
petrels (O. melania) have been documented 
recently in southern California, although this 
probably reflects greater survey efforts (Carter 
et al. 1992). In Fig. 1, similar numbers of fork- 
tailed storm-petrels (O. furcata) are indicated 
over the past decade in Oregon and California 
because survey efforts confirmed very small 
numbers. Declines in California are suspected 
(Carter et al. 1992), but further work is required 
to establish trends. 



Pelicans (Pelecanidae) 

Brown pelicans have increased recently at 
the only two remaining colonies (West Anacapa 
and Santa Barbara islands) in the Channel 
Islands in southern California (Fig. 1), follow- 
ing severe pre- 1975 declines primarily due to 
eggshell thinning from marine pollutants 
(Anderson et al. 1975; Anderson and Gress 
1983; Carter et al. 1992; F. Gress and D.W. 
Anderson, University of California-Davis, per- 
sonal communication). Breeding success is still 
low and limited recovery may involve immigra- 
tion of birds out of Mexico. Concern exists for 
adverse effects of continuing low levels of 
marine pollutants, commercial fisheries, and the 
1990 American Trader oil spill. Although the 
brown pelican has shown recent population 
increases, white pelicans have been extirpated 
from parts of interior California and have 
declined at inland colonies in northern 
California because of low reproduction related 
to water developments and drought (Carter et al. 
1992; P. Moreno and D.W. Anderson, University 
of California-Davis, personal communication). 
Small colonies still exist at Sheepy Lake and 
Clear Lake in the Klamath Basin area. These con- 
ditions also exist at other inland areas in Oregon, 
Washington, and Nevada, but problems seem 
fewer farther east. 

Cormorants (Phalacrocoracidae) 

Double-crested cormorants (Phalacrocorax 
auritus) have increased dramatically in coastal 
regions of California and Oregon (Fig. 1) 
because of reduced human disturbance, reduced 
levels of marine pollutants in southern 
California, and recent use of artificial nesting 
areas in San Francisco Bay and Columbia River 
estuaries (Gress et al. 1973; Carter et al. 1992). 
They have not increased in Puget Sound 
because of high human disturbance and preda- 
tion by bald eagles (Haliaeetus leucocephalus), 
which has caused colony abandonments (Henny 
et al. 1989; Speich and Wahl 1989; Carter et al. 
in press; U.W. Wilson, unpublished data). 
Declines have been reported at interior colonies 
in California, Oregon, and Washington due to 
water developments, human disturbance at 
colonies, and large-scale shooting of birds at 
hatcheries (during smolt releases) and at aqua- 
cultural facilities (Carter et al. in press; R.W. 
Lowe, unpublished data; R. Bayer, personal 
communication; P. Moreno, unpublished data). 
Brandt's and pelagic cormorant (P. penicillatus 
and P. pelagicus) populations have fluctuated in 
response to El Nino conditions (Ainley and 
Boekelheide 1990; Ainley et al. 1994). At the 
South Farallon Islands, these cormorants appear 
very sensitive to El Nino conditions, which 
result in quite poor reproduction and mortality 



Our Living Resources — Birds 



45 



of subadult and adult birds (Boekelheide and 
Ainley 1989; Ainley and Boekelheide 1990). 
Overall, numbers have remained stable or 
increased in most areas in the region (e.g., 
Carter et al. 1992), whereas these birds now 
occur at lower abundance than previously at the 
South Farallon Islands (Ainley et al. 1994). 
Numbers have increased in southern California, 
but the birds have suffered from gill-net and oil- 
spill mortality as well as human disturbance at 
colonies (H.R. Carter, unpublished data). 

Gulls, Terns, and Skimmers (Laridae and 
Rynchopidae) 

The predominant nesting gull on the west 
coast is the western gull (Larus occidentalis). 
Numbers have increased, especially in 
California (Fig. 2), probably because of the 
bird's use of human and fishing refuse and 
reduced human disturbance. Numbers have 
reached saturation at the world's largest colony 
at the South Farallon Islands (Ainley et al. 
1994); however, expansion is occurring at other 
major colonies in central and southern 
California (Carter et al. 1992). Glaucous- 
winged gulls (L. glaucescens) have remained 
stable or increased in Puget Sound (U.W. 
Wilson, unpublished data). 

California gulls (L. californicus) have 
recently expanded from interior colonies to nest 
in San Francisco Bay (Fig. 2; Carter et al. 1992; 
P. Woodin, San Francisco Bay Bird 
Observatory, unpublished data). They face seri- 
ous threats at inland colonies in interior 
California because of water developments. At 
the world's largest colony at Mono Lake, low 
water levels have resulted in the formation of 
land bridges to nesting islands, allowing access 
by coyotes (Canis latrans) in certain years 
(Jones and Stokes Associates 1993). Similar 
problems exist at other northern California 
colonies for many seabird and colonial water- 
bird species (W.D. Shuford, Point Reyes Bird 
Observatory, unpublished data). 

The status of California gulls at inland 
colonies in Oregon and Washington is not well 
known. Status and trends of inland colonies of 
ring-billed gulls (L. delawarensis) in California, 
Oregon, and Washington are not known, 
although problems related to low water levels 
may occur at many colonies. Many thousands 
have nested recently in northern California 
(W.D. Shuford, unpublished data). Small num- 
bers (< 500 breeding birds) also nest along the 
Washington coast (Speich and Wahl 1989). 
Small numbers (< 10 breeding birds) of 
Heermann's gulls (L. heermanni) nested in the 
early 1980's along the central California coast 
but none are known to do so now. Franklirfs 
gulls (L. pipixcan) recently nested in small 
numbers (< 100 breeding birds) at Lower 



California gull 




(1,000s) 




1 










Western gull 




(K.OOO'S) 


C 


> 




f 30 

O 

d 

^ 25 
20- 

15 
10 



Glaucous-winged gull 
(1,000's) 







ND 




Black skimmer 



(100's) 




>-H — H- 



Forster's tern 



(1.000s) 



1 SI 

o — 






Least tern 



(100's) 



10 CM CO 

O) LO 

f- CO 

5 W CO 







25— 

■ Elegant tern 

(100s) 




75-80 89-91 


79 88 


78-82 91 


75-80 89-91 


79 88 


78-82 91 


CA 


OR 
Year 


WA 


CA 


OR 
Year 


WA 



Klamath Lake, California, but their status in the 
region is not known. 

Low thousands of Caspian, Forster's, least. 
and elegant terns (Sterna caspia, S. forsteri, S. 
antillarum, S. elegans) and black skimmers 
(Rynchops niger) now occur in the region 
through increases (especially along the southern 
California coast) due to colony protection and 
use of artificial nesting sites (Speich and Wahl 
1989; Carteret al. 1992). Certain tern colonies 
have been eliminated or shifted (especially in 
San Francisco Bay) because of human distur- 
bance and red fox (Vulpei vulpes) or othei 
mammalian predation (P Woodin. unpublished 
data). Overall, least tern colonies in California 
appear somewhat stable because of extensive 
management. They undoubted!) occur at lower 



Fig. 2. Status and trends of breed- 
ing populations of gulls, terns, and 
skimmers, Small coastal popula- 
tions i'l gulls (Heermann's and 
ring-billed) and royal terns, as 
well as lanje 01 small inland popu 

lations <»i gulls (ring-billed and 
California), terns (black, gull 

hilled. Caspian, and Forster's), and 

black skimmers are not included 

M ) nil data available. no 

coastal nesting Sources ( \ 
(Hum ei al I'm. Sowlsetal. 
1980; Cartel et al 1992); ()K 
(Varoujean -un\ Pitman 1979; R W 

I owe. unpublished data I. and \\ \ 

(Speich and Wahl 1989; I W 
WiKon. unpublished data) Also 

artei et al, (in |iiess) tor dou- 
hle-eresied cormorant 



46 



Birds — Our Living Resources 




15 



10 



t 



Cassin's auklet 
(1O,0O0's) 



ND 



Pigeon guillemot 



(1,000's) 



Rhinoceros auklet 



°> la- 



's 5 - eo. — •* 

LO LO 



(10,000's) 



11 



ND 



ND 



35- 
30- 
25- 
20- 
15- 
10- 
5- 



Xantus' murrelet 



(100's) 



CO T- 




i-8C 89-91 


79 88 


78-82 91 


75-80 89-91 


79 88 


78-82 91 


CA 


OR 
Year 


WA 


CA 


OR 
Year 


WA 



Fig. 3. Status and trends of breed- 
ing populations of several alcids in 
California, Oregon, and 
Washington. Data for marbled 
murrelets and historical nesting by 
ancient murrelets are not included. 
ND — no data available; — no 
coastal nesting. Sources: CA 
(Huntetal. 1979; Sowls et al. 
1980; Carter et al. 1992); OR 
(Varoujean and Pitman 1979; R.W. 
Lowe, unpublished data); and WA 
(Speich and Wahl 1989; U.W. 
Wilson, unpublished data). Also 
sec Carter et al. (in press) for dou- 
ble-crested cormorant. 



than historical levels because of loss of nesting 
habitat, which continues to be threatened 
(Carter et al. 1992; R. Jurek, California 
Department of Fish and Game, personal com- 
munication). Low numbers (< 100 breeding 
birds) of arctic terns (S. paradisaea) have nest- 
ed in coastal Washington in the past but not now 
(Speich and Wahl 1989). Small numbers (< 100 
breeding birds) of gull-billed and royal terns (S. 
nilotica and S. maxima) recently colonized the 
southern California coast, although gull-billed 
terns have nested inland at the Salton Sea for a 
few decades. The status of black terns 
{Chlidonias niger) is not known. 

Alcids (Alcidae) 

Pigeon guillemot (Cepphus columba) popu- 
lations have remained stable overall (Fig. 3), but 
major fluctuations have occurred in response to 
El Nino events at the South Farallon Islands and 
on the Oregon coast (Hodder and Graybill 
1985; Ainley and Boekelheide 1990). A signifi- 
cant population and new nesting areas have 
been found recently in southern California, 
although higher numbers reflect both better sur- 
vey techniques and population increases (Carter 
et al. 1992). Ancient murrelets 
(Synthliboramphus antic/mis) nested on the 
Washington coast in the early 1900's but no 
longer do (Speich and Wahl 1989). Cassin's 



auklets {Ptychoramphus aleuticus) have 
declined at the largest known colony in the 
region at the South Farallon Islands, probably 
because of high gull predation and loss of bur- 
row-nesting habitat from soil erosion (Carter et 
al. 1992; W.J. Sydeman, unpublished data). 
However, lower numbers also were found at 
Prince Island in southern California where 
numbers of nesting gulls are lower. Differences 
in survey techniques probably account for part 
of the lower numbers found recently, but other 
data on soil conditions, densities of nesting 
gulls, and gull predation support a decline at the 
South Farallon Islands (W.J. Sydeman, unpub- 
lished data). Hundreds also were killed in the 
1984 Puerto Rican and 1986 Apex Houston oil 
spills (Ford et al. 1987; Page et al. 1990). 

Rhinoceros auklets (Cerorhinca monocera- 
ta) have increased throughout the region. 
Largest numbers occur at Protection and 
Destruction islands, but burrow occupancy has 
fluctuated widely between years (Wilson and 
Manuwal 1986; U.W. Wilson, unpublished 
data). The South Farallon Islands were recolo- 
nized after a 100-year absence in the early 
1970's (Ainley and Lewis 1974) and reached 
saturation levels by the late 1980's (Carter et al. 
1992; Ainley et al. 1994). Nesting has recently 
extended to the Channel Islands (Carter et al. 
1992). Thousands of rhinoceros auklets were 
killed in the 1986 Apex Houston oil spill (Page 
etal. 1990). 

The largest tufted puffin (Fratercula cirrha- 
ta) populations occur along the west coast of the 
Olympic Peninsula (Speich and Wahl 1989), but 
their status there is not well known. In Puget 
Sound, this species has declined substantially 
(U.W. Wilson, unpublished data). At small 
colonies in Oregon and California, their num- 
bers appear stable (Carter et al. 1992; Fig. 3), 
despite impacts due to El Nino at the South 
Farallon Islands (Ainley and Boekelheide 1990; 
Ainley et al. 1994). They have recently recolo- 
nized southern California where they have not 
nested since the early 1900's (Carter et al. 
1992). 

Common murres (Una aalge) are the domi- 
nant member of the breeding seabird communi- 
ty on the west coast but they have declined sub- 
stantially in central California and Washington 
(Figs. 3, 4) because of the combined effects of 
high mortality from gill-net fishing and oil 
spills plus poor reproduction during intense El 
Nino events. In central California, large histori- 
cal declines in the late 1800's and early 1900's 
almost led to the extinction of this population 
(Ainley and Lewis 1974). Population growth 
occurred, however, between the 1950's and the 
1970's, producing about 230,000 breeding birds 
by 1980-82 (Takekawa et al. 1990). Over 
70,000 murres were estimated to have been 



Our Living Resoura 



Birds 



47 



killed in gill nets in central California between 
1979 and 1987, before heavy fishing restrictions 
were imposed in 1987 to stop mortality 
(Takekawa et al. 1990). Additional mortality 
(10,000+ murres) occurred during the 1984 
Puerto Rican and 1986 Apex Houston oil spills 
(Ford et al. 1987; Page et al. 1990). At the South 
Farallon Islands, reproductive success was 
almost nil during intense El Nino events in 1983 
and 1992 (Ainley and Boekelheide 1990; W.J. 
Sydeman, unpublished data). Because of these 
and other factors, the central California popula- 
tion declined by over 60% from 1982 to 1989 
and has not recovered (Fig. 4; Takekawa et al. 
1990; Carter et al. 1992; Ainley et al. 1994; 
H.R. Carter, unpublished data). 

In Washington, murre numbers crashed dur- 
ing the 1982-83 El Nino (Wilson 1991), 
although there was heavy mortality from gill 
nets at this time; mortality from gill nets still 
continues in Puget Sound. In addition, certain 
colonies have been disturbed by low-flying air- 
craft, especially near military bases. Numbers 
of breeding murres in Washington are lower 
than indicated in Figs. 3 and 4 because many 
birds counted in colonies in recent years (and 
used to derive estimates) do not appear to be 
breeding (U.W. Wilson, unpublished data). 
Significant mortality occurred during the 1984 
Arco Anchorage, 1988 Nestucca, and 1991 
Tenyo Maru oil spills. In the Nestucca spill 
alone, about 30,000 murres were estimated to 
have died (Ford et al. 1991). The Washington 
population of murres has been almost extirpat- 
ed over the last decade and has not recovered. 

In contrast, murre populations in Oregon and 
northern California have been stable or increas- 
ing to date, despite human disturbance at sever- 
al colonies (Takekawa et al. 1990; R.W. Lowe, 
unpublished data) and some losses of Oregon 
birds from oil spills and the use of gill nets in 
Washington. In addition, these areas were 
known to experience lower productivity through 
colony abandonment during intense El Nino 
conditions in 1993 (Fig. 4; H.R. Carter, unpub- 
lished data; J.E. Takekawa and R.W. Lowe, 
unpublished data). Thus, it appears clear that 
decline and lack of recovery of populations in 
central California and Washington have resulted 
primarily from human causes, especially gill 
nets and oil spills. 

Marbled murrelets probably have declined 
substantially throughout the region largely 
because of the direct loss of most (90%-95%) of 
their old-growth forest nesting habitat to large- 
scale logging since the mid-1800's (Carter and 
Morrison 1992; FEMAT 1994). About 10,000- 
20,000 birds remain. In addition, hundreds of 
murrelets have been killed in gill nets and oil 
spills in central California, Puget Sound, and off 
the Olympic Peninsula (Carter and Morrison 



1992; H.R. Carter, unpublished data). Murrelets 
appear to have very low reproductive rates 
(based on nests examined and at-sea counts of 
juveniles), probably because of high avian nest 
predation in fragmented forests and possibly 
lower breeding success during intense El Nino 
events. This species was listed as threatened in 
California, Oregon, and Washington in 1992, 
and is being considered carefully with regard to 
the future of old-growth forests and the timber 
industry in this region. Small populations in 
California, Oregon, and southwestern 
Washington are isolated and susceptible to 
extinction from various potential disturbances 
in the future. 




Oregon 



(100,000's) 



I 



ND ND ND ND ND ND ND ND 



I 



25 
20 
15 



Central California 



(10,000's) 



ND 



ND 




ND ND ND 



ND ND 



79 80 81 82 83 



85 86 87 



Year 



90 91 92 93 



The Xantus' murrelet (Synthliboramphus 
hypoleucus) persists in very low numbers 
(2,000-5,000 breeding birds) only in southern 
California. Numbers breeding at the largest 
colony at Santa Barbara Island probably have 
declined between the mid-1970's and 1991 
(Fig. 3; Carter et al. 1992). The decline may 
have occurred because of many factors, includ- 
ing census differences. Poor reproduction, how- 
ever, has occurred because of high levels of 
avian and mammalian predation and has proba- 
bly led to this decline. Other smaller colonies 
may disappear because of mortality from oil 
spills from offshore platforms in Santa Barbara 
Channel and oil tanker traffic into Los Angeles 



Fig. 4. Status and trends of 
breeding populations of common 
murres in Washington. Oregon, 
and central California. ND — no 
data available. Sources: WA 
(Wilson 1991; U.W.Wilson, 
unpublished data); OR (Varoujean 
and Pitman 1979; R.W. Lowe, 
unpublished data); and Central 
CA (Takekawa et al. 1990; Carter 
etal. 1992; H.R. Carter and J.E. 
Takekawa, unpublished data). 



48 



Birds — Our Living Resources 



harbor and other factors. Larger numbers of 
nesting birds are now suspected in southern 
California (H.R. Carter, unpublished data). A 
significant portion of the small world popula- 
tion of this species nests in southern California 
while the remainder nests on the northwest 
coast of Baja California. Mexico. This candi- 
date species may be considered for federal and 
state listing in the near future. 

Future Efforts 

Because of the continuing decline of and 
threats to seabirds on broad regional and local 
levels along the west coast, efforts to determine 
status and trends of seabirds must be extended 
beyond current levels. Long-term efforts must 
be shared among many federal and state agen- 
cies, universities, and private groups, including 
( 1 ) the development of a coordinated long-term 
monitoring and research program, including 
data-base development and maintenance; (2) 
extending monitoring to all coastal and inland 
areas and species; (3) developing new method- 
ologies for surveying nocturnal species of mur- 
relets, auklets, and storm-petrels; (4) conduct- 
ing studies of specific conservation problems 
such as loss of nesting habitats (e.g., old-growth 
forests), gill-net mortality (e.g., Puget Sound), 
oil-spill mortality, human disturbance, water 
developments, and agricultural practices; (5) 
restoring lost or depleted seabird colonies and 
habitats; and (6) examining the possible long- 
term effects of human fisheries and global cli- 
mate change on seabird prey resources and nest- 
ing habitats. 

References 

Ainley, D.G., and R.J. Boekelheide, eds. 1990. Seabirds of 
the Farallon Islands: ecology, dynamics, and structure of 
an upwelling-system community. Stanford University 
Press. Stanford. CA. 450 pp. 

Ainley, D.G., and G.W. Hunt. Jr. 1991. The status and con- 
servation of seabirds in California. Pages 103-114 in J. P. 
Croxall, ed. Seabird status and conservation: a supplement. 
International Council of Bird Preservation Tech. Bull. 1 I. 

Ainley. D.G., and T.J. Lewis. 1974. The history of Farallon 
Island marine bird population, 1854-1972. Condor 
76:432-446. 

Ainley, D.G., W.J. Sydeman, S.A. Hatch, and U.W. Wilson. 
1994. Seabird population trends along the west coast of 
North America: causes and extent of regional concor- 
dance. Studies in Avian Biology 15:1 19-133. 

Anderson. D.W., and F. Gress. 1983. Status of a northern 
population of California brown pelicans. Condor 85:79- 
88. 

Anderson, D.W., J.R. Jehl, R.W. Risebrough. L.A. Woods. 
L.R. DeWeese. and W.G. Edgeeomb. 1975. Brown peli- 
cans: improved reproduction off the southern California 
coast. Science 190:806-808. 

Bartonek, J.C., and D.N. Netlleship, eds. 1979. 
Conservation of marine birds of northern North America. 
U.S. Fish and Wildlife Service. Wildlife Res. Rep. 11. 
319 pp. 



Boekelheide. R.J., and D.G Ainley. 1989. Age, resource 
availability, and breeding effort in Brandt's cormorant. 
Auk 106:389-401. 

Briggs, K.T.. W.B. Tyler. D.B. Lewis, and D.R. Carlson. 
1987. Bird communities at sea off California: 1975 to 
1983. Studies in Avian Biology 1 1. 74 pp. 

Carter, H.R.. and M.L. Morrison, eds. 1992. Status and con- 
servation of the marbled murrelet in North America. 
Proceedings of a 1987 Pacific Seabird Group 
Symposium. Proceedings of the Western Foundation of 
Vertebrate Zoology 5. Camarillo. CA. 134 pp. 

Carter, H.R., G.J. McChesney, D.L. Jaques, C.S. Strong. 
M.W. Parker, J.E. Takekawa. D.L. Jory. and D.L. 
Whitworth. 1992. Breeding populations of seabirds in 
California, 1989-1991. Vol 1. U.S. Fish and Wildlife 
Service, Dixon, CA. [Unpublished final report.] 

Carter, H.R., A.L. Sowls, M.S. Rodway, U.W. Wilson, R.W. 
Lowe. F. Gress, and D.W. Anderson. Status of the dou- 
ble-crested cormorant on the west coast of North 
America. Colonial Waterbirds. In press. 

Ford. R.G.. G.W. Page, and H.R. Carter. 1987. Estimating 
mortality of seabirds from oil spills. Pages 747-751 in 
Proceedings of the 1987 Oil Spill Conference. American 
Petroleum Institute, Washington, DC. 

Ford, R.G., D.H. Varoujean, D.R. Warrick. W.A. Williams. 
D.B. Lewis. C.L. Hewitt, and J.L. Casey. 1991. Seabird 
mortality resulting from the Nestucca oil spill incident 
winter 1988-89. Ecological Consulting Incorporated. 
Portland, OR. [Unpublished report.] 

Forest Ecosystem Management Assessment Team 
(FEMAT). 1994. Forest ecosystem management: an eco- 
logical, economic, and social assessment. U.S. 
Departments of Agriculture and Interior. Washington. 
DC. 

Gress, F., R.W. Risebrough. D.W. Anderson. L.F. Kiff. and 
J.R. Jehl, Jr. 1973. Reproductive failures of double-crest- 
ed cormorants in southern California and Baja 
California. Wilson Bull. 85:197-208. 

Henny, C.J., L.J. Blus, S.P. Thompson, and U.W. Wilson. 
1989. Environmental contaminants, human disturbance 
and nesting of double-crested cormorants in northwest- 
ern Washington. Colonial Waterbirds 12:198-206. 

Hodder. J., and M.R. Graybill. 1985. Reproduction and sur- 
vival of seabirds in Oregon during the 1982-83 El Nino. 
Condor 87:535-541. 

Hunt. G.L.. R.L. Pitman, M. Naughton. K. Winnett. A. 
Newman. P.R. Kelly, and K.T. Briggs. 1979. 
Reproductive ecology and foraging habits of breeding 
seabirds. Pages 1-399 in Summary of marine mammal 
and seabird surveys of the southern California Bight area 
1975-1978. Vol. 3 — Investigators' reports. Part 3. 
Seabirds — Book 2. University of California-Santa Cruz. 
For U.S. Bureau of Land Management. Los Angeles, CA. 
Contract AA550-CT7-36. [Unpublished report.] 

Jones and Stokes Associates. 1993. Environmental impact 
report for the review of Mono Basin water rights of the 
City of Los Angeles. Draft. May. (JSA 90-171.) Prepared 
for California State Water Resources Control Board. 
Division of Water Rights. Sacramento. CA. 

Nettleship. D.N.. G.A. Sanger, and P.F. Springer, eds. 1984. 
Marine birds: their feeding ecology and commercial fish- 
eries relationships. Proceedings of the Pacific Seabird 
Group Symposium. Canadian Wildlife Service Spec. 
Publ.. Ottawa, Ontario. 220 pp. 

Page, G.W., H.R. Carter, and R.G. Ford. 1990. Numbers of 
seabirds killed or debilitated in the 1986 Apex Houston 
oil spill in central California. Pages 164-174 in S.G. 
Sealy. ed. Auks at sea. Proceedings of an International 
Symposium of the Pacific Seabird Group. Studies in 
Avian Biology 14. 

Sealy. S.G.. ed. 1990. Auks at sea. Proceedings of an 
International Symposium of the Pacific Seabird Group. 
Studies in Avian Biology 14. 180 pp. 



Our Living Resources Birds 



49 



Sowls, A.L., A.R. DeGange, J.W. Nelson, and G.S. Lester. 

1980. Catalog of California seabird colonies. U.S. Fish 

and Wildlife Service, FWS/OBS 37/80. 371 pp. 
Speich, S.M., and T.R. Wahl. 1989. Catalog of Washington 

seabird colonies. U.S. Fish and Wildlife Service, 

Biological Rep. 88(6). 510 pp. 
Takekawa, J.E., H.R. Carter, and T.E. Harvey. 1990. Decline 

of the common murre in central California, 1980-1986. 

Pages 149-163 in S.G. Sealy, ed. Auks at sea. 

Proceedings of an International Symposium of the 

Pacific Seabird Group. Studies in Avian Biology 14. 
Varoujean, D.H., and R.L. Pitman. 1979. Oregon seabird 

survey 1979. U.S. Fish and Wildlife Service, Portland. 

OR. Unpublished report. 



Vermeer, K., K.T. Briggs. K.H. Morgan, and 1). Siegel- 
Causey, eds. 1993. The status, ecology, and conservation 
of marine birds of the North Pacific. Proceedings of a 
Pacific Seabird Group Symposium. Canadian Wildlife 
Service Spec. Publ. Ottawa, Ontario. 263 pp. 

Wilson, U.W. 1991. Responses of three seabird species to El 
Nino events and other warm episodes on the Washington 
coast, 1979-1990. Condor 93:853-858. 

Wilson, U.W., and D.A. Manuwal. 1986. Breeding biology 
of the rhinoceros auklet in Washington. Condor 88:143- 
155. 



For further information: 

Harry R. Carter 

National Biological Service 

California Pacific Science Center 

6924 Tremont Rd. 

Dixon, CA 95620 



About 100 million seabirds reside in marine 
waters of Alaska during some part of the 
year. Perhaps half this population is composed 
of 50 species of nonbreeding residents, visitors, 
and breeding species that use marine habitats 
only seasonally (Gould et al. 1982). Another 30 
species include 40-60 million individuals that 
breed in Alaska and spend most of their lives in 
U.S. territorial waters (Sowls et al. 1978). 
Alaskan populations account for more than 
95% of the breeding seabirds in the continental 
United States, and eight species nest nowhere 
else in North America (USFWS 1992). 

Seabird nest sites include rock ledges, open 
ground, underground burrows, and crevices in 
cliffs or talus. Seabirds take a variety of prey 
from the ocean, including krill, small fish, and 
squid. Suitable nest sites and oceanic prey are 
the most important factors controlling the natur- 
al distribution and abundance of seabirds. 

The impetus for seabird monitoring is based 
partly on public concern for the welfare of these 
birds, which are affected by a variety of human 
activities like oil pollution and commercial fish- 
ing. Equally important is the role seabirds serve 
as indicators of ecological change in the marine 
environment. Seabirds are long-lived and slow to 
mature, so parameters such as breeding success, 
diet, or survival rates often give earlier signals of 
changing environmental conditions than popula- 
tion size itself. Seabird survival data are of inter- 
est because they reflect conditions affecting 
seabirds in the nonbreeding season, when most 
annual mortality occurs (Hatch et al. 1993b). 

Techniques for monitoring seabird popula- 
tions vary according to habitat types and the 
breeding behavior of individual species (Hatch 
and Hatch 1978, 1989; Byrd et al. 1983). An 
affordable monitoring program can include but 
a few of the 1,300 seabird colonies identified in 
Alaska, and since the mid-1970's, monitoring 
efforts have emphasized a small selection of 
surface-feeding and diving species, primarily 
kittiwakes (Rissa spp.) and murres (Uria spp.). 
Little or no information on trends is available 
for other seabirds (Hatch 1993a). The existing 



monitoring program occurs largely on sites 
within the Alaska Maritime National Wildlife 
Refuge, which was established primarily for the 
conservation of marine birds. Data are collected 
by refuge staff, other state and federal agencies, 
private organizations, university faculty, and 
students. 

Status of Monitored Birds 

Kittiwakes 

Kittiwakes are small, pelagic (open sea) 
gulls that range widely at sea and feed on a vari- 
ety of small fish and plankton, which they cap- 
ture at the sea surface. Black-legged kittiwakes 
(Rissa tridacnia) have been studied intensively 
because they are widely distributed and easy to 
observe. Among 10 locations for which popula- 
tion trend data are available, 3 show significant 
declines since the mid-1970's, 3 show increas- 
es, and 4 show no consistent trends (Fig. I ). The 
overall trend is unknown, although widespread 
declines are anticipated because of a downward 



Seabirds in 
Alaska 



by 
Scott A Hatch 

John F. Piatt 
National Biological Service 




Dense colonics oi common murres I ' no aalge) 
Islands, western Gull ol Alaska 



It ledges here on the Scnmli 



50 



Birds — Our Living Resources 




BLKI (897 birds) 



St. George Is 




I — i — i — i — I — i — i — i — I — i — i — I — I — i — i — i — i — I — r- 



St. Paul Is 




RLKI (115 birds) 




(239 nests) 



100 

75- 
50 
25 
0- 

100 
75- 
50- 
25 
0- 



Semidi Is. 

~BLKI ~ 

" (480 birdsT 



V^ 



C. Thompson 




BLKI (4,088 birds) 



C. Peirce 

BLKI 
Tl ,295 birdsj~ 



IT^V 



Buldir Is 



56 60 



72 75 78 81 84 87 90 
Year 




56 60 



72 75 78 81 
Year 



84 87 



0.7- 



45 



\36 (colony years) 
\33 



Fig. 1. Population trends of black-legged kittiwakes (BLKI) and red-legged kittiwakes (RLKI) at 
selected colonies in Alaska. The maximum count of birds or nests is indicated for each location. 
Dashed lines indicate significant regressions (P < 0.05) of data collected since 1970 (P is a mea- 
sure of the confidence that the decline or increase is statistically reliable. P < 0.05 indicates a 
high probability that the population trend depicted actually occurred). See Hatch et al. 1993a and 
references cited therein for data sources. 

trend in the production of offspring (Fig. 2); 
some large colonies fail chronically. On 
Middleton Island, for example, breeding has 
been a total or near-total failure in 10 of the last 
12 years (1983-94; Hatch et al. 1993a; Hatch, 
unpublished data). The colony is declining at an 
average rate of 7% per year (equal to adult mor- 
tality), suggesting there is no recruitment (Hatch 
et al. 1993b). If survival estimates obtained on 
Middleton apply generally, the near-term future 
of kittiwakes is unfavorable because average 
productivity of 0.2 chicks per pair (Fig. 2) is 
inadequate to maintain populations. 

Where red-legged kittiwakes (R. brevi- 
rostris) have been monitored, they show popu- 
lation trends similar to black-legged kittiwakes 
(Fig. 1). In 1989 their population was down by 
50% in the Pribilof Islands, but they were more 
numerous at Buldir Island than in the 
mid-1970's (Byrd and Williams 1993). Because 
most of the world population of red-legged kit- 
tiwakes breeds in the Pribilofs (75% on St. 
George Island), their decline at that location is 
cause for concern. 




o.o 



i — i — i — i — i — i — i — i — i — 

77 79 81 83 85 
Year 



~ i — i 
87 



Fig. 2. Productivity (chicks 
fledged per nest built) of black- 
legged kittiwakes in Alaskan 
colonies, 1976-89. The number of 
colony-years included in each 
mean is indicated. See Hatch et al. 
1993a for raw data. 



Murres 

Murres are large-bodied, abundant, and 
wide-ranging seabirds that feed mostly on 
schools of fish they pursue by diving underwa- 
ter, sometimes to depths of 100-200 m (330-650 
ft). Repeated counts of one or both murre 
species (common murre, Uria aalge, and 
thick-billed murre, U. lomvia) are available for 
12 locations in Alaska (Fig. 3). Since 1970 com- 
mon murres have declined significantly at two 
colonies, and thick-billed murres have declined 
at one. Murres (species not distinguished) 
increased at two colonies over the same period. 
Between the 1950's and the 1970's, murres 
increased at one location (Middleton Island) 
and declined at another (Cape Thompson), but 
they have since been relatively stable at both 
colonies. In 1989 the Exxon Valdez oil spill 
killed substantial numbers of common murres 
at several colonies in the Gulf of Alaska (Piatt et 
al. 1990a). 

Available data are insufficient to identify 
overall trends. Murres are relatively consistent 
producers of young, averaging 0.5-0.6 chicks per 
pair annually in both species (Byrd et al. 1993). 

Threatened and Endangered Species 

No breeding seabirds are currently listed as 
threatened or endangered in Alaska. The 
short-tailed albatross (Diomedea albatrus), with 
fewer than 1,000 individuals surviving, breeds 
in Japan but visits Alaskan waters during most 
months of the year. The species is vulnerable to 
incidental take by commercial fishing gear, 
especially gill nets and longlines (Sherburne 
1993). 

Three species that breed in Alaska were 
recently listed as category 2 (possibly qualify- 
ing for threatened or endangered status, but 
more information is needed for determination): 
the red-legged kittiwake, marbled murrelet 
(Brachyramphus marmoratus), and Kittlitz's 
murrelet (B. brevirostris). As noted previously, 
red-legged kittiwakes have declined substantial- 
ly on the Pribilof Islands (Fig. 1 ). Marine bird 
surveys conducted in Prince William Sound in 
1972-73 and 1989-93 suggest a significant 
decline of marbled murrelets in that area 
(Klosiewski and Laing 1994). This finding is 
corroborated by Audubon Christmas Bird 
Counts from coastal sites in Alaska, which 
reveal a downward trend since 1972 (Piatt, 
unpublished data). Kittlitz's murrelet also 
showed a decline in the Prince William Sound 
surveys (Klosiewski and Laing 1994). With an 
estimated population of fewer than 20,000 birds 
range-wide (van Vliet 1993). this species is one 
of the rarest of auks (Family Alcidae). Both 
murrelets were adversely affected by the Exxon 
Valdez oil spill (Piatt et al. 1990a). 



Our Living Resoun < 



llmh 



SI 



Other Species 

Scant information is available to assess 
numerical changes for most seabird species in 
Alaska. We know that some species were seri- 
ously reduced or locally extirpated by foxes 
introduced to islands in the 1800's and early 
1900's. About 450 islands from southeastern 
Alaska to the western Aleutians were used as 
release sites for arctic {Alopex lagopus) and red 
foxes (Vulpes vulpes) (Bailey 1993). The species 
most affected included open-ground nesters such 
as gulls (Lams spp.), terns (Sterna spp.), and ful- 
mars (Fulmarus glacialis), and burrowing birds 
like ancient murrelets (Synthliboramphus antiqu- 
us), Cassin's auklets (Ptychoramphus aleuticus), 
tufted puffins (Fratercula cirrhatd), and 
storm-petrels (Oceanodroma spp.). In spite of 
natural die-offs and eradication efforts, foxes 
remain on about 50 islands to which they were 
introduced (Bailey 1993). 

Recent counts suggest that fulmars are 
increasing at two of their major colonies 
(Semidi Islands and Pribilof Islands), and sever- 
al small colonies have been established since 
the mid-1970's (Hatch 1993b). Counts of least 
and crested auklets (Aethia pusilla and A. 
cristatella) also indicate possible increases at 
two colonies in the Bering Sea (Piatt et al. 
1990b; Springer et al. 1993). 

Red-faced cormorants (Phalacrocorax urile) 
declined about 50% on the Semidi Islands 
between 1978 and 1993, while pelagic cor- 
morants (P. pelagicus) increased on Middleton 
Island between 1956 and the mid-1970's 
(Hatch, unpublished data). Glaucous-winged 
gulls (Larus glaucescens) increased on 
Middleton from none breeding in 1956 to more 
than 20,000 birds in 1993 (Hatch, unpublished 
data); this species has also shown marked 
increases following removal of introduced foxes 
at several sites in the Aleutian Islands (Byrd et 
al. 1994). Marine bird surveys in Prince 
William Sound (Klosiewski and Laing 1994) 
suggest that arctic terns (Sterna paradisaea), 
glaucous-winged gulls, pelagic cormorants, 
horned puffins (Fratercula cornicidata), and 
pigeon guillemots (Cepphus columba) have all 
declined in that area. Terns and guillemots have 
recently increased on several Aleutian Islands 
following fox removal (Byrd et al. 1994). 

Factors Affecting Seabirds 

Alaskan seabirds are killed incidentally in 
drift gill nets used in high seas (DeGange et al. 
1993), and oil pollution poses a significant 
threat, as demonstrated by the Exxon Valdez 
spill. There is little doubt, however, that the 
introduction of exotic animals, especially foxes, 
but also rats, voles, ground squirrels, and rabbits 




TBMU (1,335 birds) 



St. Matthew Is 



COMU (1,528 birds) 



i i i i ' i i i i 



St. Lawrence Is. 
(1.123 murres) 



100 
75 
50 
25 




100 
75 
50 
25 




Semidi Is. 



(3,117 murres) 



X^ 



Bluff 

(2,541 COMU) 




C. Peirce 



(2,749 COMU) 



xz 



C. Thompson 



100 
75 
50 
25 


100 
75 
50 
25 





St. George Is. 



(1,842 birds) 



TBMU 



C. Lisburne 
(23,428 murres) 



(19,613 birds) 



St. Paul Is 




Buldir Is 



COMU (2,933 birds) 



56 60 70 73 76 79 82 85 88 91 




56 60 70 73 76 79 82 85 88 91 



Year 



has been the most damaging source of direct 
mortality associated with human activity 
(Bailey 1993). Unlike one-time catastrophes, 
introduced predators exert a continuous nega- 
tive effect on seabird populations. 

Changes in food supply, whether natural or 
related to human activity, are another important 
influence on seabird populations. The postwar 
period from 1950 to the 1990's has seen explo- 
sive growth and constant change in commercial 
fisheries of the northeastern Pacific (Alverson 
1992). Driving these changes, or in some cases 
possibly driven by them, are major shifts in the 
composition of marine fish stocks. In the Gulf 
of Alaska, for example, a shift occurred in the 
late 1970's and early 1980s toward greater 
abundance of groundfish (cod, Gadus macro- 
cephalus: various flatfishes; and especially 
walleye pollock, Theragra chalcogramma), 
possibly at the expense of small forage species 
such as herring (Clupea harengus), sandlance 
(Ammodytes hexapterus), and capelin (Mallotm 
villosus; Alverson 1992) (Fig. 4). Coincident 
with these changes, diets of a variety of seabirds 
such as murres. murrelets, and kirtiwakes have 
shifted from being predominant]) capelin-based 



COMU 
TBMU 



murres 
regressions 



Fig. 3. Population trends ol com- 
mon natures (COMU) and 
thick-billot murres i IBMlial 
selected colonies in Alaska 
Counts of "murres" included 
unspecified numbers ol common 
and thick-billed murres. The max- 
imum count of individuals is indi- 
cated for each location Dashed 
hues indicate significant regies 
sions </' < 0.05) ol data collected 
since 1970 See Hatch 1993a foi 

data sources 



52 



Birds — Our Living Resources 



20 



Pollock 



15 



Fig. 4. Temporal changes in 
marine fish stocks of the Gulf of 
Alaska: total pollock biomass 
(age 2+) from stock assessment 
surveys by the National Marine 
Fisheries Service, 1975-90 (above; 
Marasco and Aron 1991 ), and 
catch per unit effort of capelin in 
midwater trawls in Pavlov Bay, 
western Gulf of Alaska, 1972-92 
(below; P. Anderson, NMFS, 
unpublished data). 



For further information: 

Scott A. Hatch 

National Biological Service 

Alaska Science Center 

Anchorage. AK 99503 



10 



imi 




72 74 76 78 



80 82 84 86 
Year 



88 90 



to pollock-based (Piatt, unpublished data). 
Seabird declines and breeding failures corre- 
spond to the shift, as do drastic declines in har- 
bor seals (Phoca vitulina) and northern sea lions 
(Eumetopias jubatus) in the Gulf of Alaska 
(Merrick et al. 1987; Pitcher 1990). 

The wholesale removal of large quantities of 
fish biomass from the ocean is likely to have 
major, if poorly known, effects on the marine 
ecosystem. An emerging issue is whether fish 
harvests are altering marine ecosystems to the 
detriment of seabirds and other consumers like 
pinnipeds and whales. 

The relative role of fishing and natural envi- 
ronmental variation in regulating these systems 
is another matter for long-term research. In any 
case, seabird monitoring will continue to pro- 
vide valuable insights into marine food webs, 
especially changes that affect the ocean's 
top-level consumers, including humans. 

References 

Alverson, D.L. 1992. A review of commercial fisheries and 
the Steller sea lion {Eumetopias jubatus): the conflict 
arena. Reviews in Aquatic Sciences 6:203-256. 

Bailey, E.P. 1993. Fox introductions on Alaskan islands: his- 
tory, impacts on avifauna, and eradication. U.S. Fish and 
Wildlife Service, Resour. Publ. 193. 54 pp. 

Byrd, G.V., R.H. Day, and E.P. Knudson. 1983. Patterns of 
colony attendance and censusing of auklets at Buldir 
Island, Alaska. Condor 85:274-280. 

Byrd, G.V., and J.C. Williams. 1993. Red-legged kittiwake 
(Rissa brevirostris). Pages 1-12 in The birds of North 
America, 60. A. Poole and F Gill, eds. The Academy of 
Natural Sciences. Philadelphia: The American 
Ornithologists' Union, Washington, DC. 

Byrd. G.V.. E.C. Murphy. G.W. Kaiser. A.Y. Kondratyev, and 
Y.V. Shibaev. 1993. Status and ecology of offshore 
fish-feeding alcids (murres and puffins) in the North 
Pacific. Pages 176-186 in K. Vermeer, K.T. Briggs, K.H. 
Morgan, and D. Siegel-Causey, eds. The status, ecology, 
and conservation of marine birds of the North Pacific. 
Canadian Wildlife Service. Ottawa. 

Byrd, G.V., J.L. Trapp, and C.F Zeillemaker. 1994. Removal 
of introduced foxes: a case study in restoration of native 



birds. Transactions of the 59th North American Wildlife 
and Natural Resources Conference. Wildlife Management 
Institute. Washington. DC. In press. 

DeGange, A.R.. R.H. Day. J.E. Takekawa. and V.M. 
Mendenhall. 1993. Losses of seabirds in gill nets in the 
North Pacific. Pages 204-21 1 in K. Vermeer, K.T. Briggs, 
K.H. Morgan, and D. Siegel-Causey, eds. The status, ecol- 
ogy, and conservation of marine birds of the North Pacific. 
Canadian Wildlife Service, Ottawa. 

Gould, P.J., D.J. Forsell, and C.J. Lensink. 1982. Pelagic dis- 
tribution and abundance of seabirds in the Gulf of Alaska 
and eastern Bering Sea. U.S. Fish and Wildlife Service 
FWS/OBS-82/48. 294 pp. 

Hatch, S.A. 1993a. Population trends of Alaskan seabirds. 
Pacific Seabird Group Bull. 20:3-12. 

Hatch, S.A. 1993b. Ecology and population status of northern 
fulmars Fulmarus glacialis of the North Pacific. Pages 
82-92 in K. Vermeer, K.T. Briggs, K.H. Morgan, and D. 
Siegel-Causey, eds. The status, ecology, and conservation 
of marine birds of the North Pacific. Canadian Wildlife 
Service, Ottawa. 

Hatch, S.A.. G.V. Byrd, D.B. Irons, and G.L. Hunt, Jr. 1993a. 
Status and ecology of kittiwakes {Rissa tridactyla and R. 
brevirostris) in the North Pacific. Pages 140-153 in K. 
Vermeer, K.T. Briggs. K.H. Morgan, and D. Siegel-Causey. 
eds. The status, ecology, and conservation of marine birds 
of the North Pacific. Canadian Wildlife Service. Ottawa. 

Hatch, S.A., and M.A. Hatch. 1978. Colony attendance and 
population monitoring of black-legged kittiwakes on the 
Semidi Islands, Alaska. Condor 90:613-620. 

Hatch, S.A., and M.A. Hatch. 1989. Attendance patterns of 
murres at breeding sites: implications for monitoring. 
Journal of Wildlife Management 53:483-493. 

Hatch, S.A., B.D. Roberts, and B.S. Fadely. 1993b. Adult sur- 
vival of black-legged kittiwakes Rissa tridactyla in a 
Pacific colony. Ibis 135:247-254. 

Klosiewski, S.P., and K.K. Laing. 1994. Marine bird popula- 
tions of Prince William Sound, Alaska, before and after the 
Exxon Valdez oil spill. U.S. Fish and Wildlife Service, 
Anchorage. AK. 89 pp. 

Marasco, R., and W. Aron. 1991. Explosive evolution — the 
changing Alaska groundfish fishery. Reviews in Aquatic- 
Sciences 4:299-315. 

Merrick. R.L.. T.R. Loughlin. and D.G. Calkins. 1987. 
Decline in abundance of the northern sea lion. Eumetopias 
jubatus, in Alaska, 1956-86. Fishery Bull. 85:351-365. 

Piatt, J.F., C.J. Lensink, W. Butler, M. Kendziorek. and D.R. 
Nysewander. 1990a. Immediate impact of the "Exxon 
Valdez" oil spill on marine birds. Auk 107:387-397. 

Piatt. J.F., B.D. Roberts, and S.A. Hatch. 1990b. Colony 
attendance and population monitoring of least and crested 
auklets on St. Lawrence Island. Alaska. Condor 92:97- 1 06. 

Pitcher. K.W. 1990. Major decline in number of harbor seals. 
Phoca vitulina richardsi. on Tugidak Island, Gulf of 
Alaska. Marine Mammal Science 6:121-134. 

Sherburne. J. 1993. Status report on the short-tailed albatross 
Diomedea albatrus. U.S. Fish and Wildlife Service. 
Ecological Services. Anchorage. AK. 58 pp. 

Sowls, A.L., S.A. Hatch, and C.J. Lensink. 1978. Catalog of 
Alaskan seabird colonies. U.S. Fish and Wildlife Service 
FWS/OBS-78/78. 254 pp. 

Springer, A.M., A.Y. Kondratyev. H. Ogi. Y.V. Shibaev, and 
G.B. van Vliet. 1993. Status, ecology, and conservation of 
Synthliboramphus mtirrelets and auklets. Pages 187-201 in 
K. Vermeer. K.T Briggs. K.H. Morgan, and D. 
Siegel-Causey. eds. The status, ecology, and conservation 
of marine birds of the North Pacific. Canadian Wildlife 
Service. Ottawa. 

USFWS. 1992. Alaska seabird management plan. U.S. Fish 
and Wildlife Service. Division of Migratory Birds. 
Anchorage. AK. 102 pp. 

van Vliet, G. 1993. Status concerns for the "global" popula- 
tion of Kittlitz's murrelet: is the "glacier murrelet" reced- 
ing? Pacific Seabird Group Bull. 20:15-16. 



Our Living Resources — Birds 



S3 



Colonial waterbirds, that is, seabirds (gulls, 
terns, cormorants, pelicans) and wading 
birds (herons, egrets, ibises), have attracted the 
attention of scientists, conservationists, and the 
public since the turn of the century when plume 
hunters nearly drove many species to extinction. 
The first national wildlife refuge at Pelican 
Island, Florida, was founded to conserve a large 
nesting colony of the brown pelican {Pelecanus 
occidentalis). The National Audubon Society 
also established a game warden system to mon- 
itor and protect important waterbird colonies. 
These efforts helped establish federal laws to 
protect migratory birds and their nesting habi- 
tats in North America. 

Although the populations of many species 
rebounded in the early part of the 20th century, 
major losses and alteration of coastal wetlands 
still threaten the long-term sustainability of 
many colonial waterbirds. A national, coordi- 
nated monitoring program is needed to monitor 
population status and trends in colonial water- 
birds (Erwin et al. 1993). The Canadian 
Wildlife Service has recently established a 
national seabird monitoring program (D. 
Nettleship, CWS, personal communication). In 
addition, better coordination and cooperation 
for monitoring waterbirds are needed on both 
their breeding grounds in North America and 
their wintering grounds in Latin America where 
wetland loss is also a critical problem (Erwin et 
al. 1993). This article summarizes the status 
and trends of selected waterbird species in 
North America, but excludes Alaska, Hawaii, 
and the Pacific coast, which are described else- 
where. 

Population Surveys 

Data on the population status of colonial 
waterbirds come from many sources. The 
Breeding Bird Survey (Peterjohn and Sauer 
1993) is useful as a visual index for the more 
widely distributed species that occur along 
coasts and across the interior of the United 
States and Canada (e.g., great blue herons 
[Ardea herodias] and herring gulls [Larus 
argentatus]), but it is not effective for many 
waterbird species that nest in wetlands. 

Recently, Christmas Bird Count (CBC) data 
have been analyzed, providing an index to num- 
bers of wintering birds (J.R. Sauer, National 
Biological Service, personal communication). 
For waterbirds, these counts must be used with 
caution since water conditions can have a major 
effect on the feeding distribution of waterbirds 
during the count period in December. Thus, 
trends in CBC counts may indicate more about 
trends in wetland conditions than trends in pop- 
ulations of any particular waterbird species. 



More precise estimates of species' popula- 
tions at colony sites have been conducted over 
the years by state, federal, and private organiza- 
tions. Although a few states (e.g., Florida, 
Illinois, Massachusetts, Texas, and Virginia) 
have conducted annual surveys over a long peri- 
od for at least some species, there is little con- 
sistency among their methods and the frequen- 
cy of surveys (Erwin et al. 1985). Many data on 
breeding populations are kept at the state level, 
but these data seldom predate 1980, precluding 
assessment of long-term trends in many of these 
long-lived species. 

Even though more than 50 species of colo- 
nial waterbirds breed in the United States, 
Canada, and Mexico, this article focuses on the 
22 species for which sufficient data are avail- 
able to indicate population changes, at least at a 
regional level. 




Pelecaniformes 

Pelicans and their allies (cormorants, anhin- 
gas) suffered from DDT use, and their numbers 
plummeted to the point where the eastern and 
California brown pelicans became endangered. 
The eastern subspecies, however, was recently 
removed from the threatened list because of its 
rapid numerical and range increases (Table). 

The American white pelican (Pelecanus <r\ 
throrhynchos) has shown similar sharp increas- 
es in the western regions of Canada and die- 
United States (Evans and Knopf L993). Double- 



Colonial 
Waterbirds 

by 

R. Michael Erwin 

National Biological Service 



Common tern (Sterna hirundo) 



54 



Birds — Our Living Resources 



Table. Regional, national, and 
continental population status and 
trends of selected colonial water- 
birds in the United States" as 
reported by the Breeding Bird 
Survey, Christmas Bird Counts, 
and other sources. 



Species 


Region 


Population status 


BBS/CBC trend" 
% change % +/-routes 


Years 




Early period 


Recent period 


References 


Pelecaniformes 


American white pelican 


Continent 






+5.3" 




1966-91 


BBS 


U.S. 


17,872 nests (1964) 


22,299 nests (1980-81) 








1 


Canada 


14,103 (1967-69) 


53,345 (1985-86) 








1 


Mexico 


Sporadic (100 nests) 










1 


U.S. 






+3.8"' 




1966-89 


CBC (winter) 


Eastern brown pelican 


U.S. 


7,800-8,300(1970-76) 


26,461 (1989) 


NA 


«-' 




2 


Double-crested cormorant 


Continent 






+6.5*" 


+0.61"* 


1966-91 


BBS 


U.S. 






+2.3" 


+0.61*" 






Canada 






+11.5"* 


+0.64* 






U.S. 






+8.2*** 




1966-89 


CBC (winter) 


Ciconiiformes 


Great blue heron 


Continent 






+1.5" 


0.60*" 


1966-91 


BBS 




U.S. 






+1.9 


0.61"* 








Canada 






+0.7 ns 


0.54* 






Great blue heron 


U.S. 






+2.2*" 




1966-89 


CBC 


Snowy egret 


U.S. 






+2.0" 




1966-89 


CBC 


Reddish egret 


U.S. Gulf coast 


1,700-2,200 pr. (1976-78) 


1,370-1,900 pr. (1989-90) 








3,4,5,6 


Black-crowned night-heron 


U.S. 






+2.8 




1966-89 


CBC 


White ibis 


Southeast U.S. 


40,000-80,000 pr.(1967-71) 


22,000-50,000 pr. (1987-93) 








7 




U.S. 






+5.0** 




1966-89 


CBC 


White-faced ibis 


Western U.S. 


4,500-5,500 pr. (1967-75) 


13,000-13,500 pr. (1985) 








8 


U.S. 






+7.6** 




1966-89 


CBC 


Wood stork 


Southeast U.S. 


2,500-5,200 pr. (1976-82) 


6,729 pr. (1993) 








9,10 




U.S. 






+1.3 ns 




1966-89 


CBC 


Charadriiformes 


Razorbill 


N. Gulf St. Lawrence, Can. 


16,200 birds (1960) 


2,380 birds (1982) 








11 


Atlantic puffin 


Canada (Witless Bay) 


300,000-340,000 pr.(1973) 


225,000 pr.(1978-80) 








11 




• U.S. 


125 pr. (1977) 


135pr.(1993) 








12 


Great black-backed gull 


U.S. 






+3.6" 




1966-89 


CBC 


Herring gull 


Atlantic coast U.S. 


110,000 pr.(1 978-82) 


< 100,000 pr. (1988-92) 








13 




U.S. 






+0.5 ns 




1966-89 


CBC 


Ring-billed gull 


Continent 






+7.9" 


+0.60'" 


1966-91 


BBS 


U.S. 






+16.5" 


+0.58*" 






Canada 






+5.7* 


+0.62"* 






U.S. 






+4.2*" 




1966-89 


CBC 


Franklin's gull 


Continent 






-6.0 ns 




1966-91 


BBS 




U.S. 






-19.2"* 










Canada 






-1.2 ns 








Gull-billed tern 


Mid-Atlantic U.S. (VA-SC) 


1,100-1,600 pr. (1977) 


1,125-1625 pr. (1993) 








14,15,16 


Gulf coast U.S. (TX-AL) 


1,200-2,100 pr, (1977) 


3,000 pr. (1990) 








3,4,5 


U.S. 






-1.5* 




1966-89 


CBC 


Forster's tern 


Continent 






-2.4 ns 


-0.58* 




BBS 




U.S. 






-3.2 ns 


-0.60" 




BBS 




Canada 






Insult, data 










U.S. 






f4.3*" 






CBC 


Common tern 


Great Lakes U.S. 


1,691 nests (1977) 


1,916 nests (1989) 








17,18 


Roseate tern 


N. Atlantic U.S. 


2,855-3,285 pr. (1976-80) 


3,200 pr. (1993) 








19,20 




U.S. Caribbean 


Uncertain pre-1975 


1,900-2,500 pr. (1975-80) 








13,18 


Least tern (interior ssp.) 


Mississippi River 


4,100-4,700 birds (1986-87) 


6,833 birds (1991) 






1986-91 


21 


Black tern 


Continent 






-3.9" 


-0.59*" 


1966-92 


BBS 




U.S. 






-5.6'" 


-0.64*" 








Canada 






-3.4 


-0.52 ns 







Excluding Alaska, Hawaii, and the Pacific coast states. 

"Breeding Bird Survey trends statistically test for an annual (% change) trend (H : trend = 0) and % of increasing (+) or decreasing (-) routes (H : no. 
routes + = no. routes -). Probability levels: *P< 0.10;" P< 0.05; *" P< 0.01. A lower Pvalue means there is more confidence that the trend is real. A 
population trend change at the P< 0.10 level is considered statistically significant; ns = not significant. Christmas Bird Count trends are conducted similar 
to annual BBS trend (JR. Sauer, NBS, unpublished data). 

c Sources: numbers refer to literature reference number; BBS = Breeding Bird Survey results (JR. Sauer and B. Peterjohn, NBS, personal communica- 
tion); CBC = Christmas Bird Count trend results (JR. Sauer, personal communication). 

1— Evans and Knopf 1993; 2— P. Wilkerson, South Carolina Wildlife and Marine Resources Department; 3— Lange, in press; 4— Portnoy 1978; 5— Martin 
and Lester 1990; 6— Runde 1991; 7— P. Frederick, University of Florida, unpublished data; 8— D. Manry, unpublished data; 9— Ogden et al. 1987; 10— J. 
Ogden and M. Coulter, National Park Service, unpublished data; 11— Nettleship and Birkhead 1985; 12— B. Allen, Maine Department of Inland Fisheries 
and Wildlife, unpublished data; 13— Nisbet, in press; 14— Spendelow and Patton 1988; 15— Erwin 1979; 16— J. Parnell and P. Wilkerson, University of 
North Carolina and South Carolina Wildlife and Marine Resources Department, unpublished data; 17— Scharf et al. 1992; 18— Blokpoel and Tessier 1993; 
19— Gochfeld 1983; 20— J.A. Spendelow, NBS, unpublished data; 21— E. Kirsch and J. Sidle, NBS, unpublished data. 



crested cormorant (Phalacrocorax auritus) pop- 
ulations also declined during the 1940-70 peri- 
od, probably because of DDT and other pesti- 
cides; however, this species has increased dra- 
matically across Canada and the northern 
United States (Table). In the Great Lakes and 



elsewhere, this species' increases have attracted 
considerable attention because of the negative 
effects on fisheries and on the aquaculture 
industry (Blokpoel and Scharf 1991; Blokpoel 
and Tessier 1991; Nettleship and Duffy, in 
press). 



Our Living Resoun < 



limit 



55 



Ciconiiformes 

Heron, egret, and ibis nesting colonies were 
reduced along much of the U.S. coastline in the 
early 1900's as a result of the millinery trade; 
however, the species have all recovered their 
former ranges. Great blue herons are the most 
abundant and ubiquitous of the wading birds in 
North America; all indications suggest that their 
populations have increased, especially in the 
United States (Butler 1992; Table). One reason 
for this trend may be that winter survival has 
increased as herons feed heavily at aquaculture 
facilities in the southern United States. 

The reddish egret {Egretta rufescens) is list- 
ed as a species of management concern to the 
USFWS (OMBM 1994). It nests in small num- 
bers along the gulf coast and in southern Florida 
(Table). Reddish egrets seem to have declined 
some in Texas (Lange, in press) and Louisiana 
(Portnoy 1978; Martin and Lester 1990; 
Figure), but the data are not adequate in Florida 
to assess trends. 

Snowy egrets (E. thula) were prized by 
plume traders at the turn of the century, and the 
species suffered dramatic population declines; 
however, by the 1970's these egrets had recov- 
ered their former range. More recently, their 
populations declined in some Atlantic regions 
such as Virginia (Williams et al. 1990) and 
southern Florida (Robertson and Kushlan 1974; 
Ogden 1978; Table). 

The black-crowned night-heron {Nycticorax 
nycticorax), which occurs across all of North 
America, may be declining in parts of Canada, 
south to Texas (Davis 1993) and perhaps 
Virginia (Williams et al. 1990; Table). 

Ibises are more nomadic in their breeding 
distribution than are other wading birds. White 
ibis (Eudocimus albus) have declined markedly 
in southern Florida as a result of hydrologic 
changes in the Everglades (Robertson and 
Kushlan 1974; Ogden 1978). Their breeding 
distribution has shifted northward, and large 
colonies exist in Georgia and the Carolinas 
(Ogden 1978; Bildstein 1993). Over the entire 
southeastern United States the species may not 
have undergone major changes, although state 
estimates have been erratic (twofold changes in 
2-3 years; Table). 

The white-faced ibis (Plegadis chihi) was 
formerly (1987) on the USFWS management 
concern list, but is not on the 1994 national list 
(OMBM 1994). Population data for the central 
and western populations (noncoastal) indicate a 
marked increase in the numbers of these ibis 
from the early 1970's to 1985 (D. Manry, per- 
sonal communication; Table). 

Wood storks (Mycteria americana), which 
have been federally listed as endangered since 
1984, nest from Florida north to South Carolina 



in the United States, in Cuba, and in enormous 
numbers in the river deltas of eastern Mexico, 
especially the Usumacinta-Grijalva Delta. Stork 
colonies have shifted north from the Everglades 
to central and northern Florida, Georgia, and 
South Carolina since the 1970's (Robertson and 
Kushlan 1974; Ogden 1978; Ogden et al. 1987). 
Recent inventories of nesting populations in the 
United States indicate a modest increase in 
numbers over the past 10-15 years (Table; 
Figure). 

Because of the mobility of wood storks and 
ibis, monitoring them requires a regional 
approach to ensure standardization in survey 
timing and methods. Individual state inventories 
are inadequate to address many highly mobile 
species. 

Charadriiformes 

This order of colonial-nesting waterbirds 
includes the alcids (murres, puffins, auks), 
shorebirds, gulls, terns, and black skimmers 
(Rynchops niger). Although some species of 
alcids and terns were nearly extirpated by 
hunters or millinery traders during the early 
1900's, they rebounded well in many areas. 

Alcid populations are rare in the eastern 
United States. In maritime Canada, however, 
alcid numbers are substantial (Nettleship and 
Birkhead 1985; Erskine 1992), though there is 
concern over Canada's razorbill (Alca tarda) 
populations, which declined by more than 75% 
from 1960 to 1982 (Nettleship and Birkhead 
1985). These declines may be the result of con- 
flicts with commercial fisheries. 

Canadian populations of Atlantic puffins 
(Fratercula arctica) have declined a great deal 
in some areas. The largest Atlantic puffin 
colony in North America is at Witless Bay, 
Newfoundland (61% of continental breeding 
total); this colony has declined by 25%-35% 
from 1973 to 1980 (Nettleship and Birkhead 
1985). Again, competition between birds and 
commercial fisheries (capelin) may be causing 
much of the decline. In Maine, a successful 
transplant program has been in effect for more 
than a decade to reintroduce nesting Atlantic 
puffins onto several coastal islands (Kress and 
Nettleship 1988); numbers remain small, how- 
ever (Table). 

Gull populations have increased substantial- 
ly from the middle part of the century to the pre- 
sent (Buckley and Buckley 1984; Nisbet. in 
press). Great black-backed gulls (Lams mari- 
nus) have increased in some mid-Atlantic states 
but have probably declined in Maine (Nisbet. in 
press; Table). Herring gull populations probably 
peaked around 1980 at about 110.000 pairs 
along the northeastern U.S. coastline, but popu- 
lations may have declined during the 1980's 



endangered 



I of concern 



5 4 



Wood stork 



76-82 



93 
Roseate lern, North 
Atlantic population 




20- 



76-80 
Interior least tern 



93 




35- 



86-87 



20 



■i 15 



1 Reddish egret 
Jt 



76-78 



89-90 



Black tern 



V^, 



•s 1 



"^.\. 



U ' ' M ' : I I I | | M M J I I I I | I I F I | I 

66 71 76 81 86 91 
Year 

Kijjure. Trends i»l selected colo 
nial waterbirds either endangered 
oi (in the I s Fish and Wildlife 
Service's list <>i species ol man 
agemenl concern in the lower is 
states (excluding the Pacific coast) 
Black tern trends are count indices 
from the Breeding Hint Survej 
(mean 01 average numbei ol birds 
pa nnito. Lightei coloi "•!>»>« -- 
range of variation in estimates. 



56 



Birds — Our Living Resources 



(Nisbet, in press); BBS and CBC data do not 
show any change (Table). Changes in landfill 
practices that have reduced food supplies along 
the northeastern coast may have reduced winter 
survival and slowed the population growth of 
this species. In the Great Lakes, however, her- 
ring gulls have shown a dramatic increase since 
the late 1970's. 

Ring-billed gulls (L. delawarenis) continue 
to increase across the northern tier of states, 
Canada, and the Great Lakes (Blokpoel and 
Scharf 1991; Blokpoel and Tessier 1991; 
Table). The BBS and CBC data suggest signifi- 
cant increases in the United States and Canada 
(Table). Refuge and resource managers are con- 
cerned over the reported decline in the 
Franklin's gull (L. pipixcan), an interior, marsh- 
nesting species that may be vulnerable to agri- 
cultural pesticides (White and Kolbe 1985). The 
BBS trends indicate that the numbers of this 
species significantly declined in the United 
States from 1966 to 1991. However, adding 
1992 and 1993 data indicates a nonsignificant 
decline in the United States, which raises the 
question of the value of BBS data for this flock- 
feeding species (J.R. Sauer, personal communi- 
cation). 

Gull-billed terns (Sterna nilotica) are a 
species of special concern to many coastal 
states and were on the former (1987) USFWS 
management list. Recent population figures 
from Texas (Lange, in press), Louisiana (Martin 
and Lester 1990), and the mid- Atlantic region 
(Virginia to South Carolina) suggest that the 
population is reasonably stable over the long 
term but erratic from year to year (Table). 

The Forster's tern (5. forsteri) nests both 
along coasts and across the interior of the north- 
ern tier of states and Canadian provinces. State 
surveys do not suggest declines in most states 
from New Jersey (CD. Jenkins, New Jersey 
Division of Fish, Game and Wildlife, personal 
communication) to Virginia (Erwin 1979). Data 
are insufficient in the Great Lakes to assess 
trends. The trends from the BBS and CBC are 
contradictory, with breeding trends indicating 
declines and wintering trends a significant 
increase. This species is erratic in its nesting 
and probably not sampled well by either of 
these surveys. 

Common terns (S. hirundo), while abundant 
and increasing along the U.S. northeastern coast 
(Buckley and Buckley 1984), are considered 
endangered, threatened, or a species of special 
concern in six Great Lakes states and Ontario 
(Blokpoel and Scharf 1991; Scharf et al. 1992). 
Even though tern numbers increased from 1977 
to 1989 in the U.S. Great Lakes (Table), the 
number of their colony sites has declined from 
31 to 23. Competition with the ring-billed gull 
is a major factor in this decline (Scharf et al. 



1992). 

The roseate tern (S. dougallii) is an endan- 
gered species (since 1987) and breeds in two 
populations in the western Atlantic. The west- 
ern North Atlantic population includes the mar- 
itime provinces south to Long Island, New York 
(with a few possibly from New Jersey to 
Georgia); the U.S. Neotropical population is 
confined to Puerto Rico, the Virgin Islands, and 
southern Florida. In the northern population, the 
number of breeding pairs ranged from 2,855 to 
3,285 pairs during the 1976-80 period 
(Gochfeld 1983) to 3,200 estimated pairs in 
1993 (J. Spendelow, National Biological 
Service, personal communication; Table; 
Figure). In the southern U.S. population, pair 
estimates from the 1976-79 period range from 
about 1,900 (Gochfeld 1983) to about 2,600 
pairs in the Florida Keys. Puerto Rico, and the 
Virgin Islands (Blokpoel and Tessier 1993; 
Table). Earlier records are sparse in this region, 
making trends difficult to determine. 

The least tern (S. antillarum) is divided into 
three subspecies in the United States and 
Canada; the interior (S.a. athalassos) and 
California (S.a. browni) subspecies are listed as 
endangered. In the Mississippi River drainages, 
the interior least tern seems to have increased 
from the 1986-87 period to 1991 (E. Kirsch and 
J. Sidle, NBS, unpublished data; Table; Figure). 
The 1993 floods probably prevented recent 
nesting in many river stretches. 

The black tern (Chlidonias niger) is listed as 
either endangered or a species of concern in 
many northern states, including New York. 
Iowa, Illinois, Wisconsin, Ohio, and Indiana. Its 
population has decreased at the BBS continen- 
tal and U.S. levels from 1966 to 1992 (Table; 
Figure). From 1982 to 1991, BBS data indicate 
a significant increase in Canada with continued 
decrease in the United States. This suggests a 
species' displacement to the north, possibly a 
result of changes in wetland conditions in the 
northern tier of the United States. A confound- 
ing factor may also be that the Canadian surveys 
have been more intensive for this species in 
recent years. 

References 

Bildstein. K.L. 1993. White ibis: wetland wanderer. 
Smithsonian Institution Press, Washington. DC. 242 pp. 

Blokpoel. H., and W.C. Scharf. 1991. Status and conserva- 
tion of seabirds nesting in the Great Lakes of North 
America. Pages 17-41 in J. Croxall. ed. Status and con- 
servation of the world's seabirds. International Council 
for Bird Preservation, Cambridge. England. 

Blokpoel, H.. and G.D. Tessier. 1991. Distribution and 
abundance of colonial waterbirds nesting in the Canadian 
portions of the lower Great Lakes system in 1990. 
Canadian Wildlife Service Tech. Rep. Series 117. 16 pp. 

Blokpoel. H.. and G.D. Tessier. 1993. Atlas of colonial 
waterbirds nesting on the Canadian Great Lakes. 1989- 
1991. Part I. Cormorants, culls, and island-nesting terns 



Our Living Resources — Birds 



57 



on Lake Superior in 1989. Canadian Wildlife Service 
Tech. Rep. Series 181. 96 pp. 

Buckley, P. A., and F.G. Buckley. 1984. Seabirds of the north 
and middle Atlantic coasts of the United States: their sta- 
tus and conservation. Pages 101-134 in J. P. Croxall, 
P.G.H. Evans, and R.W. Schreiber, eds. International 
Council for Bird Preservation Tech. Publ. 2. Cambridge, 
England. 

Butler. R.W. 1992. Great blue heron (Ardea herodias). 
Pages 1-20 in A. Poole and F. Gill, eds. The birds of 
North America, No. 25. Academy of Natural Sciences, 
Philadelphia, PA, and The American Ornithologists' 
Union, Washington, DC. 

Davis, W.E., Jr. 1993. Black-crowned night-heron 
(Nycticorax nycticorax). Pages 1-20 in A. Poole and F. 
Gill, eds. The birds of North America, No. 74. Academy 
of Natural Sciences, Philadelphia, PA, and The American 
Ornithologists' Union, Washington, DC. 

Erskine, A.J. 1992. Atlas of breeding birds of the maritime 
provinces. McCurdy Printing, Halifax, Nova Scotia. 270 
pp. 

Erwin, R.M. 1979. Coastal waterbird colonies: Cape 
Elizabeth, Maine to Virginia. U.S. Fish and Wildlife 
Service FWS/OBS-79/10. 212 pp. 

Erwin, R.M., PC. Frederick, and J.L. Trapp. 1993. 
Monitoring of colonial waterbirds in the United States: 
needs and priorities. Pages 18-22 in M. Moser, R.C. 
Prentice, and J. van Vessem, eds. Waterfowl and wetland 
conservation in the 1990's — a global perspective. 
Proceedings of the International Waterfowl and Wetlands 
Research Bureau Symposium, St. Petersburg Beach, FL. 
International Waterfowl and Wetlands Research Bureau 
Special Publ. 26, Slimbridge, UK. 

Erwin, R.M., PH. Geissler, M.L. Shaffer, and D.A. 
McCrimmon, Jr. 1985. Colonial waterbird monitoring: a 
strategy for regional and national evaluation. Pages 342- 
357 in W. McComb, ed. Proceedings of a Workshop on 
Management of Nongame Species and Ecological 
Communities. University of Kentucky Agricultural 
Experiment Station, Lexington. 

Evans, R.M., and F.L. Knopf. 1993. American white pelican 
{Pelacanus erythrorhynchos). Pages 1-24 in A. Poole and 
F. Gill, eds. The birds of North America, No. 57. 
Academy of Natural Sciences, Philadelphia PA. and The 
American Ornithologists' Union.Washington, DC. 

Gochfeld, M. 1983. The roseate tern: world distribution and 
status of a threatened species. Biological Conservation 
25:103-125. 

Kress, S.W., and D.N. Nettleship. 1988. Re-establishment 
of Atlantic puffin (Fratercula arctica) at a former breed- 
ing site in the Gulf of Maine. Journal of Field 
Ornithology 59:161-170. 

Lange, M. Texas coastal waterbird colonies: 1973-1990 
census summary, atlas, and trends. U.S. Fish and Wildlife 
Service and Texas Parks and Wildlife Department, 
Angleton, TX. 209 pp. In press. 

Martin, R.P, and G.D. Lester. 1990. Atlas and census of 
wading bird and seabird colonies in Louisiana, 1990. 



Louisiana Department of Wildlife and Fisheries and 
Louisiana Natural Heritage Program, Special Publ. 3, 
Baton Rouge. 182 pp. 

Nettleship. D.N., and T.R. Birkhead, eds. 1985. The Atlantic 
Alcidae. Academic Press, New York. 574 pp. 

Nettleship, D.N., and D.C. Duffy, eds. The double-crested 
cormorant: biology, conservation, and management. 
Colonial Waterbirds 17 (Special Publ.). In press. 

Nisbet, I.C.T Seabirds of the eastern United States: status 
and conservation. In D.N. Nettleship, ed. Seabirds of 
North America: status and conservation requirements. A 
special science publication in association with Stichting 
Greenpeace Council, Amsterdam, The Netherlands. In 
press. 

OMBM. 1994. Migratory nongame birds of management 
concern in the United States: the 1994 list. U.S. Fish and 
Wildlife Service, Office oi Migratory Bird Management, 
Washington, DC. 

Ogden, J.C. 1978. Recent population trends of colonial 
wading birds on the Atlantic and Gulf Coastal Plains. 
Pages 137-154 in A. Sprunt, IV. J.C. Ogden, and S. 
Winckler, eds. Wading birds. National Audubon Society 
Res. Rep. 7, New York. 

Ogden, J.C, D.A. McCrimmon. Jr., G.T. Bancroft, and 
B.W. Patty. 1987. Breeding populations of the wood 
stork in the southeastern United States. Condor 89:752- 
759. 

Peterjohn, B.G.. and J.R. Sauer. 1993. North American 
Breeding Bird Survey annual summary, 1990-91. Bird 
Populations 1:1-15. 

Portnoy. J.W. 1978. Nesting colonies of seabirds and wad- 
ing birds-coastal Louisiana, Mississippi, and Alabama. 
U.S. Fish and Wildlife Service FWS/OBS-77/07. 102 pp. 

Robertson, W.B., Jr., and J. A. Kushlan. 1974. The south 
Florida avifauna. Pages 414-452 in Memoir 2 environ- 
ments of south Florida: present and past. Miami 
Geological Society report, FL. 

Runde, D. 1991. Trends in wading bird nesting populations 
in Florida, 1976-78 and 1986-89. Final performance 
report, Division of Wildlife, Florida Game and 
Freshwater Fish Commission, Tallahassee. 

Scharf, W.C., G.W. Shugart. and J.L. Trapp. 1992. 
Distribution and abundance of gull, tern and cormorant 
colonies of the U.S. Great Lakes, 1989 and 1990. U.S. 
Fish and Wildlife Service, Office of Migratory Bird 
Management, Washington, DC. 89 pp. 

Spendelow, J. A., and S.R. Patton. 1988. National atlas of 
coastal waterbird colonies in the contiguous United 
States: 1976-82. U.S. Fish and Wildlife Service 
Biological Rep. 88(5). 326 pp. 

White, D.H., and E.J. Kolbe. 1985. Secondary poisoning of 
Franklin's gulls in Texas by monocrotophos. Journal of 
Wildlife Diseases 21:76-78. 

Williams, B., J.W. Akers, J.W. Via. and R.A. Beck. 1990. 
Longitudinal surveys of the beach nesting and colonial 
waterbirds of the Virginia barrier islands, 1975-1987. 
Virginia Journal of Science 41:381-388. 



For further information: 

R. Michael Erwin 

National Biological Service 

Patuxent Environmental Science 

Center 

114 10 American Holly Dr. 

Laurel. MD 20708 



The North American group of shorebirds 
includes 48 kinds of sandpipers, plovers, 
and their allies, many of which live for most of 
the year in coastal marine habitats; others live 
principally in nonmarine habitats including 
grasslands, freshwater wetlands, and even sec- 
ond-growth woodlands. Most North American 
shorebirds are highly migratory, while others 
are weakly migratory, or even nonmigratory in 
some parts of their range. Here we discuss 
shorebirds east of the 105th meridian (roughly 



east of the Rocky Mountains). Historically, 
populations of many North American species 
were dramatically reduced by excessive gun- 
ning (Forbush 1912). Most populations recov- 
ered after the passage of the Migratory Bird 
Treaty Act of 1918, although some species 
never recovered and others have declined again. 
High proportions of entire populations of 
shorebirds migrate by visiting one or a small 
number of "staging sites,'" areas where the birds 
accumulate fat to provide fuel before continuing 



Shorebirds: 
East of the 
105th 
Meridian 



58 



Birds — Our Living Resources 



by 

Brian A. Harrington 

Manomet 

Observatory for Conservation 

Sciences 



with their long-distance, nonstop flights to the 
next site (Morrison and Harrington 1979; 
Senner and Howe 1984; Harrington et al. 1991). 
Growing evidence (Schneider and Harrington 
1981) indicates that staging areas are unusually 
productive sites with highly predictable but sea- 
sonally ephemeral "blooms" of invertebrates, 
which shorebirds use for fattening. In some 
cases, especially for "obligate" coastal species, 
specific sites are traditionally used; even other 
species sites may shift between years. Because 
of this, conservationists believe some species 
are at risk through loss of strategic migration 
sites (Myers et al. 1987). Other species are 
threatened by the loss of breeding and wintering 
habitats (Page et al. 1991; Haig and Plissner 
1993; B. Leachman and B. Osmundson, U.S. 
Fish and Wildlife Service, unpublished data). 

The predicted consequences of global warm- 
ing, such as sea-level change, will also strongly 
affect the intertidal marine habitats, which 
many species of shorebirds depend upon. Some 
of the strongest warming effects will be at high 
latitudes, including those where many shore- 
birds migrate to breed, as well as south temper- 
ate latitudes, where many of them winter. 

Population Trend Data 

Information on population trends in North 
American shorebirds comes largely from stud- 
ies designed for other purposes, except in the 
case of a few species that breed within latitudes 
covered by the Breeding Bird Survey (BBS) and 
one game species, the American woodcock 
(Scolopax minor). We divide these studies into 
two types, those based on surveys during breed- 
ing and nonbreeding seasons. 

Population trend data from breeding seasons 
come mostly from studies of declining or 
threatened species such as piping plovers 
(Charadrius melodus; Haig and Plissner 1993), 
mountain plovers (C. montanus; Graul and 
Webster 1976; F.L. Knopf, U.S. Fish and 
Wildlife Service, unpublished data), and snowy 
plovers (G alexandrinus; Page et al. 1991). 
Additional data come from the BBS and from 
special survey efforts on game species such as 
American woodcock (Sauer and Bortner 1991). 

Nonbreeding season data come mostly from 
aerial surveys of migrants on Delaware Bay 
during spring (Clark et al. 1993), of migrants by 
the International Shorebird Surveys (ISS) dur- 
ing spring and fall (Harrington et al. 1989), and 
by the Maritimes Shorebird Surveys (MSS) in 
eastern Canada during fall (Morrison et al. 
1994). Although none of these projects was 
designed principally to gather data for popula- 
tion trend monitoring, they are the only data 
bases on migrant species that have been sys- 
tematically compiled through a period of years. 



The Christmas Bird Counts are an exception; 
they are conducted when most shorebirds are 
south of the United States. 

Largely voluntary efforts of the ISS of 
Manomet Observatory, the MSS of the 
Canadian Wildlife Service, the BBS of the 
National Biological Service, and surveys on 
Delaware Bay (DELBAY) coordinated by New 
Jersey and Delaware state wildlife agencies 
have produced rough data useful for trend 
analysis. Because the BBS is conducted during 
the breeding season and is based on roadside 
surveys, its value is greatest in analyzing popu- 
lation change of broadly distributed shorebirds 
common in temperate latitudes where survey 
effort is greatest. The ISS, MSS, and DELBAY 
projects have focused on migration season 
counts and, therefore, are the best (though not 
ideal) available resources for monitoring north- 
ern-breeding shorebirds, which include most 
species in North America. 

Plovers 

Three of the eight species of plover that reg- 
ularly occur east of the 105th meridian (snowy 
plover, piping plover, and mountain plover) are 
species of concern (endangered, threatened, or 
candidate species); killdeer (C. vociferus) and 
perhaps black-bellied plover (Pluvialis 
squatarola) are in decline (Table). In North 
America, all of these except the black-bellied 
plover are distributed principally in temperate 
latitudes; snowy, piping, and mountain plovers 
breed in special, localized habitats (principally 
sandy beaches, salt lakes, and salt flats for 
snowy and piping plovers, short-grass prairie 
for mountain plovers). There has been no evalu- 
ation of trends for Wilson's plover {Charadrius 
wilsonia), typically a beach-nesting species in 
southern North America. There are no statisti- 
cally significant population changes in 
American golden- (P. dominica) and semi- 
palmated plovers (C. semipalmatus). 

Oystercatchers, Avocets, and Stilts 

No significant population changes have been 
detected in the three species of these groups east 
of the 105th meridian (Table). 

Sandpipers 

This is the largest family of shorebirds. Five 
species of this family listed in the Table — willet 
(Catoptrophorus semipalmatus), upland sand- 
piper (Bartramia longicauda), long-billed 
curlew (Numenius americanus), marbled' god- 
wit (Limosa fedoa), and American woodcock — 
commonly breed in the contiguous 48 United 
States. Two others, the long-billed curlew, 
which nest principally in short-grass prairie, 
and the American woodcock found in second- 



Our Living Resources Hints 



5 ( > 



growth woodland, show significant population 
declines. Upland sandpipers (tall-grass habitats, 
including croplands) show a significant 
increase. The remaining sandpiper species 
breed principally north of the contiguous 48 
states. Six of these — ruddy turnstone {Arenaria 
interpres), red knot (Calidris canutus), sander- 
ling (C. alba), white-rumped sandpiper (C. fus- 
cicollis), Baird's sandpiper (C bairdii), and 
buff-breasted sandpiper (Tryngites 

subruficollis) — are principally high-latitude 
breeders; two (red knot and sanderling) of the 
three species for which trend analysis data are 
available are in decline (Table). The remaining 
species can be grouped as taiga or middle Arctic 
breeders; seven of these have not been evaluat- 
ed for population trend change; five species — 
whimbrel (Numenius phaeopus), semipalmated 
sandpiper (Calidris pusilla), least sandpiper (C. 
minutilla), short-billed dowitcher 

(Limnodromus griseus), and common snipe 
(Gallinago gallinago) — were in significant 
decline (Table), and four species — greater and 
lesser yellowlegs (Tringa melanoleuca and T. 
flavipes), spotted sandpiper (Actitis tnacularia), 
and dunlin (C. alpina) — showed no significant 
change (Table). No species showed significant- 
ly increased population trends. 

Phalaropes 

Only one (Wilson's phalarope; Phalaropus 
tricolor) of the three species of North American 
phalaropes has been evaluated for population 
change, and it showed significant declines 
(Table). 

Summary and 
Recommendations 

Population trend evaluation has been con- 
ducted for 27 of 41 shorebird species common 
in the United States east of the 105th meridian. 
Of the 27 species for which trend data are avail- 
able, 12 show no change, 1 increased, and 14 
decreased (Table). There were no clear correla- 
tions with habitat. 

It is important that shorebird populations are 
monitored nationally, yet most species are hard 
to monitor because they inhabit regions that are 
difficult to access for much of the year. 
Migration seasons appear to be the most practi- 
cal time for monitoring most species. 
Unfortunately, sampling for population moni- 
toring during nonbreeding seasons presents a 
group of unresolved analytical challenges. 
Additional work on existing data can help iden- 
tify how or whether broad, voluntary, or profes- 
sional networks can collect data that will better 
meet requirements for monitoring population 
change. 



References 

Chirk. K.E., L.J. Niles, and J. Burger. 1993. Abundance and 
distribution of migrant shorebirds in Delaware Bay. 
Condor 95:69-705. 

Forbush, E.H. 1912. Game birds, wild-fowl, and shore 
birds. Massachusetts State Board of Agriculture, Boston. 
622 pp. 

Graul, W.D., and L.E. Webster. 1976. Breeding status of the 
mountain plover. Condor 78:265-267. 

Haig, S.. and J.H. Plissner. 1993. Distribution and abun- 
dance of piping plovers: results and implications of the 
1991 international census. Condor 95: 145-156. 

Harrington, B.A., F.J. Leeuwenberg, S. Lara Resende. R. 
McNeil, B.T. Thomas, J.S. Grear, and E.F. Martinez. 
1991. Migration and mass change of white-rumped sand- 
pipers in North and S >uth America. Wilson Bull. 
103:621-636. 



Table. Species, major habitats, 
and population change in North 
American breeding shorebirds in 
the United States east of the 1 05th 
meridian.* 



Scientific name 


Common name 


Habitat 


Reference 
and status 


Significance 




Pluvialis squatarola 


Black-bellied plover 


Coastal 


a- d+ 


P< 0.10(a) ns(d) 




P. dominica 


American golden-plover 


Upland 


d- 


ns 




Charadrius alexandrinus 


Snowy plover 


Coastal 


g threatened 






C. wilsonia 


Wilson's plover 


Coastal 


unknown 






C. semipalmatus 


Semipalmated plover 


Mixed 


a- d+ 


ns(a) ns(d) 




C. melodus 


Piping plover 


Coastal 


c threatened 






C. vociterus 


Killdeer 


Upland 


b- 


P<0.05 




C. montanus 


Mountain plover 


Upland 


b+ 


ns 




Haematopus palliatus 


American oystercatcher 


Coastal 


unknown 






Himantopus mexicanus 


Black-necked stilt 


Fresh water 


b- 


ns 




Recurvirostra americana 


American avocet 


Fresh water 


b- 


ns 




Tringa melanoleuca 


Greater yellowlegs 


Mixed 


a- 


ns 




T. Ilavipes 


Lesser yellowlegs 


Mixed 


a+ 


ns 




T solitaria 


Solitary sandpiper 


Fresh water 


unknown 






Catoptrophows semipalmatus 


Willet 


Coastal 


a± b+ d- 


ns(a) ns(b) ns(d) 




Actitis macularia 


Spotted sandpiper 


Fresh water 


b+ 


ns 




Bartramia longicauda 


Upland sandpiper 


Upland 


b+ 


P<0.05 




Numenius phaeopus 


Whimbrel 


Coastal 


a-d+ 


P< 0.01(a) ns(d) 




N. americanus 


Long-billed curlew 


Upland 


b- 


P<0.05 




Limosa haemastica 


Hudsonian godwit 


Coastal 


unknown 






L ledoa 


Marbled godwit 


Mixed 


b+ 


ns 




Arenaria interpres 


Ruddy turnstone 


Coastal 


a- d+ e- 


ns(a) ns(d) ns(e) 




Calidris canutus 


Red knot 


Coastal 


a d- e- 


ns(a) P< 0.10(d) ns(e) 




C. alba 


Sanderling 


Coastal 


a- d- e- 


P< 0.01(a) ns(d)P< 0.01(e) 


C. pusilla 


Semipalmated sandpiper 


Mixed 


a- d- e- 


ns(a)P< 0.02(d) P< 0.05(e) 


C. mauri 


Western sandpiper 


Mixed 


unknown 






C. minutilla 


Least sandpiper 


Mixed 


a+ d- 


ns(a)P< 0.05(d) 




C. fuscicollis 


White-rumped sandpiper 


Mixed 


unknown 






C. bairdii 


Baird's sandpiper 


Fresh water 


unknown 






C. melanotos 


Pectoral sandpiper 


Fresh water 


unknown 






C. maritima 


Purple sandpiper 


Coastal 


unknown 






C. alpina 


Mixed 


d-e± 


ns(d) ns(e) 




C himantopus 


Stilt sandpiper 


Fresh water 


unknown 






Tryngites subrulicollis 


Buff-breasted sandpiper 


Upland 


unknown 






Limnodromus griseus 


Short-billed dowitcher 


Coastal 


a- d- e+ 


P< 0.05(a) P< 08(d) P = 012(e) 


L scolopaceus 


Long-billed dowitcher 


Fresh water 


unknown 






Gallinago gallinago 


Common snipe 


Fresh water 


b- 


P<0.05 




Scolopax minor 


American woodcock 


Special 


b-f- 


P< 0.05(b) P< 0.05(f) 




Phalaropus tricolor 


Wilson's phalarope 


Fresh water 


b- 


P<0 05 




P.lobatus 


Red-necked phalarope 


Special 


unknown 






P. tulicana 


Red phalarope 


Special 


unknown 







' In the "reference and status" column and the "significance" column, "a" through "g" refer to a reference in footnote " The 
reference footnotes also give the years the survey was conducted. If "+" follows the letter in the "reference and status* col- 
umn, the population is increasing. II "-" follows the letter, the population is declining. In the "significance" column, "ns" means 
population increase or decrease is not significant. "P" is a measure ot the confidence that the decline or increase is actually 
significant. A lower Pvalue means there is more confidence that the trend is real. A population trend change at the P< 0.10 
level is considered statistically significant, 
"a- Howe et al. (1989) for 1972-83. 

b— B.G. Peterphn, NBS, unpublished analysis, National Biological Service. Breeding Bird Survey, 1982-91 

c — Haig and Plissner 1993 

d— Morrison et al., in press 1974-91. 

e- Clark etal. 1993 for 1986-92. 

f — Sauer and Bortner 1991. 

g— U. S. Fish and Wildlife Service, Office of Endangered Species, unpublished data 



60 



Birds — Our Living Resources 



For further information: 

Brian A. Harrington 

Manomet Observatory for 

Conservation Sciences 

Manomet. MA 02345 



Harrington, B.A., J.P. Myers, and J.S. Grear. 1989. Coastal 
refueling sites for global bird migrants. Pages 4293-4307 
in O.T. Magoon, H. Converse, D.Miner, L.T. Tobin, and 
D. Clark, eds. Proceedings of the Sixth Symposium on 
Coastal and Ocean Management. American Society of 
Civil Engineers, New York. 

Howe, M.A., P.H. Geissler, and B.A. Harrington. 1989. 
Population trends of North American shorebirds based 
on the International Shorebird Survey. Biological 
Conservation 49:185-200. 

Morrison. R.I.G., C. Downes, and B. Collins. 1994. 
Population trends of shorebirds on fall migration in east- 
ern Canada, 1974-1991. Wilson Bull. 106. In press. 

Morrison, R.I.G., and B.A. Harrington. 1979. Critical 
shorebird resources in James Bay and eastern North 
America. Pages 498-507 in Transactions of the 44th 
North American Wildlife and Natural Resources 
Conference. Wildlife Management Institute. Washington. 
DC. 



Myers, J. P., R.I.G. Morrison, P.Z. Antas, B.A. Harrington. 

T.E. Lovejoy, M. Sallaberry, S.E. Senner, and A. Tarak. 

1987. Conservation strategy for migratory species. 

American Scientist 75:19-26. 
Page, G., L.E. Stenzel, W.D. Shuford, and C.R. Bruce. 

1991. Distribution and abundance of the snowy plover on 

its western North American breeding grounds. Journal of 

Field Ornithology 62:245-255. 
Sauer, J.R., and J.B. Bortner. 1991. Population trends from 

the American woodcock singing-ground survey. 1970- 

88. Journal of Wildlife Management 55:300-312. 
Schneider, DC. and B.A. Harrington. 1981. Timing of 

shorebird migration in relation to prey depletion. Auk 

98:197-220. 
Senner, S.E., and M.A. Howe. 1984. Conservation of 

Nearctic shorebirds. Pages 379-421 in J. Burger and B. 

Olla, eds. Shorebirds: breeding behavior and popula- 
tions. Plenum Press, New York. 



Western 
North 
American 
Shorebirds 

by 

Robert E. Gill, Jr. 

Colleen M. Handel 

National Biological Service 

Gary W. Page 
Point Reyes Bird Observatory 



Shorebirds are a diverse group that includes 
oystercatchers, stilts, avocets, plovers, and 
sandpipers. They are familiar birds of 
seashores, mudflats, tundra, and other wetlands, 
but they also occur in deserts, high mountains, 
forests, and agricultural fields. Widespread loss 
and alteration of these habitats, especially wet- 
lands and grasslands during the past 150 years, 
coupled with unregulated shooting at the turn of 
the century, resulted in population declines and 
range contractions of several species throughout 
North America. In the western portion of the 
continent, efforts to monitor the status and 
trends of shorebirds have been in effect for only 
the past 15-25 years and for only a few species. 
Methods exist to monitor population trends for 
most shorebirds, but only broadscale, interna- 
tional efforts, relying largely on volunteer help, 
will accomplish this. 

In this article we address shorebirds primar- 
ily in western North America, the region west of 
the Continental Divide from northern Alaska to 
southern Mexico. The 12 states, a Canadian 
province and territory, and the western portion 
of Mexico within this region represent about 
25% of the North American landmass (Fig. 1). 
Western North America includes portions of 
three broad ecological domains: the Polar 
Domain, encompassing the tundra and boreal 
forests that cover most of Greenland, Canada, 
and Alaska; the Humid Temperate Domain, 
including the humid midlatitude forests and 
shrublands within the United States, southern 
portions of the Canadian prairie provinces, and 
along the west coast of North America; and the 
Dry Domain, encompassing the short-grass 
prairies, sagebrush provinces, and deserts (Fig. 
1; Bailey 1978, 1989). 



Sources of Data 

We derived seasonal distribution of shore- 
birds within these ecological domains from 
numerous sources, mostly range maps in field 
guides, books, and our familiarity with the birds 
within the region (AOU 1983; Robbins et al. 
1983; Hayman et al. 1986; Godfrey 1987; 
National Geographic Society 1987; Paulson 
1993). 

No continent-wide protocol exists for moni- 
toring the status and trends of North American 
shorebirds. Current information has largely 
been acquired through independent programs 
sponsored by a combination of federal, state, 
and private conservation agencies. Efforts have 
mostly been regional, including broadscale 
monitoring directed primarily at birds during 
the nonbreeding season (Howe et al. 1989; Gill 
and Handel 1990; Page et al. 1992; Skagen and 
Knopf 1993; Morrison et al. 1994) or have 
focused on individual species (Handel and Dau 
1988; Gill et al. 1991; Page et al. 1991; Haig 
1992; Handel and Gill 1992a; Knopf 1994; F.L. 
Knopf, USFWS, unpublished report). We have 
relied primarily on this information and that of 
our ongoing studies to summarize the status and 
trends of shorebirds in western North America. 

Shorebirds of the Region 

Breeding 

Among the 5 1 species that regularly breed in 
North America, 47 (92%) do so within western 
North America (Table). Within this region, the 
Polar Domain supports the greatest number of 
breeding species (37), including 5 that breed 
nowhere else on the continent. The Humid 



Our Living Resources — Birds 



61 



Temperate Domain provides breeding areas for 
20 species while only 12 breed in the Dry 
Domain (Fig. 1). The number of species breed- 
ing within the domains in the West generally 
exceeds those breeding east of the Continental 
Divide, even though the eastern area is much 
larger. 

Western North American shorebirds nest in a 
variety of habitats, although most species (53%) 
are restricted to either coastal or interior wet- 
lands (Page and Gill 1994). About a third of the 
species nest primarily on uplands, especially 
Arctic and subarctic tundra and dry temperate 
grasslands. 

Wintering 

Thirty-six (70%) of the continent's breeding 
species winter in western North America, 
including seven that are restricted to the region 
(Table). The continental distribution of species 
shifts southward in winter, but numbers are still 
higher in the West than in the East (Fig. 1 ). Only 
4 of the 37 species breeding in the Polar 
Domain of western North America remain there 
during winter. About 30 species spend the win- 
ter in the Humid Temperate and Dry domains. 
Populations of 12 (25%) of western North 
America's breeding species spend the winter 
entirely on other continents or throughout 
Oceania (see glossary; Table). 

Most shorebirds use a much broader range 
of habitats during winter than during the breed- 
ing period. All species use one or more coastal 
habitats in winter and two-thirds of the species 
also use interior habitats (Page and Gill 1994). 
Wetlands, the single-most important habitat 
both along the coast and in the interior of west- 
ern North America, are used by about 80% of all 
species. Sandy and rocky shorelines along the 
Pacific coast are also important habitats and are 
used by about a quarter of the species (Page and 
Gill 1994). 

Migrating 

All species of North American shorebirds 
are migratory to some degree, with the possible 
exception of both species of oystercatchers and 
Wilson's plover; they are not migratory in the 
true sense but do make short, local movements. 
Shorebirds migrate in spring and fall over three 
broadly defined corridors encompassing the 
western, central, and eastern portions of the 
continent to wintering areas in North, Central, 
and South America (Morrison and Myers 1 989). 
Other migratory corridors funnel Arctic breed- 
ers from western North America across the 
Pacific Ocean to wintering areas in Asia, 
Australasia, and Oceania (see glossary; Gill and 
Handel 1981; Handel and Gill 1992b; Page and 
Gill 1994). The distances traveled between 



No. wintering 
species 



No. nesting 
species 



High (30-40) 




breeding and wintering grounds vary greatly 
within and among species, often exceeding 
8,000 km (5,000 mi) for such species as 
Hudsonian and bar-tailed godwits. 

Wetlands are the most important habitat 
used by shorebirds during spring and fall migra- 
tions. Throughout western North America about 
140 discrete wetlands and several additional 
wetland complexes (e.g., Central Valley of 
California) have been identified as being impor- 
tant to shorebirds during these periods (Fig. 2). 
Most staging areas (85%) host populations of 
1,000-10,000 birds, but 18 sites support 
100,000-1 million shorebirds during the peak of 
migration (Fig. 2). Because shorebirds use dif- 
ferent migration pathways and strategies during 
spring and fall, the locations of critical staging 
areas shift between the two seasons (Fig. 2). 



Status and Trends 

Size of Populations 

Population estimates exist for only about a 
quarter of the species that breed or winter in 
western North America (Table), and even these 
few vary widely in terms of statistical rigor and 
precision. These estimates range between 



Fig. 1. Number of shorebird 
species regularly breeding and 
wintering within three broad eco- 
logica 1 domains of North America 
west and east of the Continental 
Divide (dashed line). 



62 



Birds — Our Living Resources 



Table. Seasonal occurrence and status and trends of populations of shorebirds in North America west and east of the Continental Divide. 



Species 



Occurrence 



Population 



Breeding 



Wintering 



Size 



Trend 



Black-bellied plover (Pluvialis squatarola) 
Pacific golden-plover (P. fulva) 
American golden-plover (P. dominica) 
Snowy plover {Charadrius alexandrinus) 

Wilson's plover (C. wilsonia) 
Common ringed plover (C. hiaticula) 
Semipalmated plover (C. semipalmatus) 
Piping plover (C. melodus) 
Killdeer (C. vociferus) 

Mountain plover (C. montanus) 



Both regions Both regions 

Western Western 

Both regions Absent 

Both regions Both regions 



Both regions 
Eastern 
Both regions 
Eastern 
Both regions 



Both regions 
Absent 
Both regions 
Mostly eastern 
Both regions 



Unknown 
Unknown 
Unknown 
18,500 b 

Unknown 
Unknown 
Unknown 
4,700 b 
Unknown 



Both regions Mostly western 5,000-15,000 b 



American oystercatcher (Haematopus palliatus) Both regions Both regions Unknown 

Black oystercatcher (H. bachmam) Western Western 7,600 b 

Black-necked stilt (Himantopus mexicanus) Both regions Both regions 25,000 w 

American avocet (Recun/irostra americana) Both regions Both regions 100,000+ w 



Greater yellowlegs (fringa melanoleuca) 
Lesser yellowlegs ( T. flavipes) 
Solitary sandpiper ( T. solitaria) 
Willet (Catoptrophorus semipalmatus) 



Wandering tattler (Heteroscelus incanus) 
Spotted sandpiper [Actitis macularia) 



Both regions 
Both regions 
Both regions 
Both regions 



Hudsonian godwit {Limosa haemastica) 
Bar-tailed godwit (L lapponica) 
Marbled godwit (L fedoa) 



Ruddy turnstone (Arenaria interpres) 

Black turnstone (A. melanocephala) 

Surfbird (Aphriza virgata) 

Red knot (Calidris canutus) 

Sanderling (C. alba) 

Semipalmated sandpiper (C. pusilla) 

Western sandpiper (C. maun) 

Least sandpiper (C. minutilla) 

White-rumped sandpiper (C. luscicollis) 

Baird's sandpiper (C. bairdii) 

Pectoral sandpiper (C. melanotos) 

Purple sandpiper (C. maritima) 

Rock sandpiper (C. plilocnemis) 

Dunlin (C. alpina) 

Stilt sandpiper (C. himantopus) 

Buff-breasted sandpiper ( Tryngites subruficollis) 

Short-billed dowitcher (Limnodromus griseus) 

Long-billed dowitcher (L scolopaceus) 

Common snipe (Gallinago gallinago) 

American woodcock (Scolopax minoi) 
Wilson's phalarope (Phalaropus tricolor) 



Red-necked phalarope (Plobatus) 
Red phalarope (P. fulicaria) 



Both regions 
Both regions 
Both regions 
Both regions 



Western Western 

Both regions Both regions 



Upland sandpiper (Bartramia longicauda) Both regions Absent 



Eskimo curlew (Numenius borealis) 
Whimbrel (N. phaeopus) 
Bristle-thighed curlew (N. tahitiensis) 
Long-billed curlew (N. americanus) 



Unknown 
Unknown 
Unknown 
Unknown 



Unknown 
Unknown 



Unknown 



Both regions 


Absent 


25-50 b 


Both regions 


Both regions 


Unknown 


Western 


Absent 


7,000 b 


Both regions 


Both regions 


Unknown 


Both regions 


Absent 


Unknown 


Western 


Absent 


25,000-40,000 b 


Both regions 


Both regions 


100,000+ w 


Both regions 


Both regions 


Unknown 


Western 


Western 


61 ,000-99,000 b 


Western 


Western 


50,000-70,000 s 


Both regions 


Both regions 


Unknown 


Both regions 


Both regions 


Unknown 


Both regions 


Absent 


Unknown 


Western 


Both regions 


Unknown 


Both regions 


Both regions 


Unknown 


Both regions 


Absent 


Unknown 


Both regions 


Absent 


Unknown 


Both regions 


Absent 


Unknown 


Eastern 


Eastern 


Unknown 


Western 


Western 


Unknown 


Both regions 


Both regions 


450,000-600,000 ' 


Both regions 


Both regions 


Unknown 


Both regions 


Absent 


Unknown 


Both regions 


Both regions 


Unknown 


Both regions 


Both regions 


Unknown 


Both regions 


Both regions 


Unknown 


Eastern 


Eastern 


Unknown 


Both regions 


Both regions 


1,500,000 f 


Both regions 


Absent 


Unknown 


Both regions 


Western 


Unknown 



Unknown 

Unknown 

Unknown 

Population decline and range contraction past century; significant decline in western region past 

25 yr (Page et al. 1991; Page and Gill 1994) 

Unknown 

Unknown 

Declining (Haig 1992) 

Decline of 2.0% per yr in western region past 25 yr; 5.3% decline per yr last 10 yr (J. Sauer and S. 
Droege, NBS, unpublished data) 

Population decline and range contraction past century; continental decline 3.6% per yr 
past 25 yr (Knopf 1994; F.L. Knopf, USFWS, unpublished report) 
Unknown 

Unknown (Page and Gill 1994) 

Population decline and range contraction past century; no significant change in population 
size past 25 yr (Page and Gill 1994; J. Sauer and S. Droege, NBS, unpublished data) 
Population decline past century; decline of 3.6% per yr in western region past 10 yr 
(Page and Gill 1994; G. Page, unpublished data; J. Sauer and S. Droege, NBS, unpublished data) 
Unknown 
Unknown 
Unknown 

Population decline and range contraction past century; population increase of 2.8% per 
yr in United States past 25 yr; 0.5% increase in West in past 10 yr (Page and Gill 1994; 
J. Sauer and S. Droege, NBS, unpublished data) 
Unknown 

Population stable over continent and western region past 25 yr (J. Sauer and S. Droege, 
NBS, unpublished data) 

Population decline and range contraction past century; 3.6% annual increase on continental 
basis past 25 yr; no significant trend in western region (Page and Gill 1994; J. Sauer and 
S. Droege, NBS, unpublished data) 

Almost extirpated over past century; may be extinct (Gollop et al. 1986; Alexander et al. 1991) 
Unknown 

Unknown (Gill and Redmond 1992; C. Handel, unpublished data) 
Population decline and range contraction over past century; annual decrease of 3.0% on 
continental basis past 10 yr (J. Sauer and S. Droege, NBS, unpublished data) 
Unknown 

Unknown (Page and Gill 1994; R. Gill, unpublished data) 

Population decline and range contraction over past century; no significant trend throughout 
continent or western region past 25 yr (Page and Gill 1994; G. Page, unpublished data; 
J. Sauer and S. Droege, NBS, unpublished data) 
Unknown 

Unknown (Handel and Gill 1992a) 
Unknown (Page and Gill 1994) 
Unknown 
Unknown 
Unknown 
Unknown 
Unknown 
Unknown 
Unknown 
Unknown 
Unknown 
Unknown 
w Unknown (Page and Gill 1994) 
Unknown 
Unknown 
Unknown 
Unknown 

Population stable past 25 yr but 3.9% decline per yr on continental basis during past 10 yr; decline 
in western region not significant past 10 yr (J. Sauer and S. Droege, NBS, unpublished data) 
Unknown 

Population decline past century; expansion of range past 50 yr; annual population declines 
of 7.5% throughout United States and 8.1% in central region during past 10 yr (Jehl 1988; 
Page and Gill 1994; J. Sauer and S. Droege, NBS, unpublished data) 
Unknown 
Unknown 




Population estimates for Western North America unless otherwise stated (see Fig. 1 
ual birds for b — breeding season, f — fall, w — winter, and s — spring. Geographic 



). Sources for estimates of population size given with trend information. Population size ■ 
regions under population trend are defined in Robbins et al. (1986). 



- estimated number of individ- 



Our Living Resources — Birds 



63 



10,000 and 100,000 individuals for most popu- 
lations, but number from as few as 25 birds for 
the endangered Eskimo curlew to about 
500,000 for the Pacific race of the dunlin 
(Calidris alpina pacifica). A few other species 
for which some data are available, such as west- 
ern sandpiper and Wilson's phalarope, have 
populations that exceed a million (Page and Gill 
1994). 

Population Trends 

For most species, reliable quantitative data 
on population trends are either not available or 
too recent to assess trends. Assessment of long- 
term population trends is based largely on his- 
torical accounts of relative abundance and dis- 
tribution and knowledge of habitat alteration 
within breeding and wintering ranges. 
Nonetheless, populations of several species of 
western North American shorebirds have 
declined significantly over the past 150 years 
(Page and Gill 1994). One Arctic breeder, the 
Eskimo curlew, is on the verge of extinction 
(Gollop et al. 1986; Alexander et al. 1991). 
Conversion of native grasslands for agriculture, 
loss of wetlands, and market hunting before the 
turn of the century have been attributed as fac- 
tors primarily responsible for these declines. No 
species is known to have increased in overall 
population size over this period. 

Information on more recent population 
trends comes primarily from the North 
American Breeding Bird Survey (BBS), a sys- 
tem of roadside surveys designed primarily to 
monitor populations of breeding landbirds. The 
BBS does not sample most western shorebird 
breeding populations very well because of its 
sporadic coverage, poor sampling of wetland 
habitats, and lack of coverage of the most 
important shorebird breeding grounds in the 
Arctic, which are roadless. Despite these limita- 
tions, BBS does provide valuable trend infor- 
mation, particularly for grassland species in the 
temperate zone. Additional information on pop- 
ulation trends can also be obtained from surveys 
that target species of concern, such as the snowy 
plover (Page et al. 1991), or particular habitats 
of concern, such as the Arctic Coastal Plain of 
Alaska (D. Troy Ecological Assoc, and British 
Petroleum Exploration, unpublished report; 
Andres 1994). 

Recent survey data show a mixture of 
declining, increasing, and apparently stable 
population trends (Table). Over the past 25 
years, western populations of willet and upland 
sandpiper appear to have been rebounding (J. 
M. Sauer and S. Droege, unpublished data). 
Numbers of several other species, such as the 
black-necked stilt, marbled godwit, and spotted 
sandpiper, appear to have stabilized (J.M. Sauer 
and S. Droege, unpublished data). Western pop- 




ulations of several other species, however, have 
significantly declined over the past 25 years, 
including the snowy plover, killdeer, mountain 
plover, American avocet, long-billed curlew, 
common snipe, and Wilson's phalarope (Table). 
Such relatively short-term trends among wet- 
land species are difficult to interpret, however, 
as they may reflect changes in distribution in 
response to drought conditions rather than 
absolute declines in population size (Page and 
Gill 1994). 

Most changes in populations appear linked 
to habitat alteration. For example, since 1970 
the snowy plover, heavily dependent on coastal 
habitats, has disappeared as a breeding species 
from over 60% of its historic California nesting 
sites (Page and Stenzel 1981). Introducing 
plants to stabilize sand dunes, increasing recre- 
ational use of beaches, and heavy nest predation 
by feral foxes threaten to reduce coastal popula- 
tions further (Page and Gill 1994). Fluctuating 
water levels in interior wetlands result in unpre- 
dictable changes in availability of nesting habi- 
tat away from the coast (Page et al. 1991 ). The 
breeding range of the mountain plover has con- 
tracted markedly in several western states and 
the continental population has declined signifi- 
cantly during the past 25 years, probably 
because of habitat degradation on wintering 
grounds in central and southern California 
(Knopf 1994; F.L. Knopf, NBS. unpublished 



Fig. 2. Location of important 
staging areas in western North 
America used by shorebirds dur- 
ing spring and fall migration. Size 
of dot indicates the estimated peak 
number of shorebirds at each site. 



64 



Birds — Our Living Resources 



report). Given the substantial loss of wetlands 
throughout all western states except Alaska 
(median loss of 37%; Page and Gill 1994) and a 
similar loss of native grasslands (Knopf 1994), 
it is likely that other species of temperate-breed- 
ing shorebirds for which we have no trend data 
have also suffered population declines. 

Shorebirds breeding throughout the remote 
and sparsely populated Polar Domain have been 
least affected by loss of breeding habitats. Most 
of these species, however, are dependent on 
wetlands and other greatly altered habitats out- 
side this region during winter and migration. 
Information from long-term studies in Europe 
suggests that populations of Arctic-breeding 
shorebirds can be affected by conditions on the 
wintering grounds as well as by those on the 
breeding grounds (Goss-Custard and Moser 
1988; Moser 1988). Arctic breeders such as the 
buff-breasted sandpiper, upland sandpiper, and 
American golden-plover winter primarily in 
grassland habitats of the pampas in South 
America. These habitats have been virtually 
eliminated by agricultural development (Bucher 
and Nores 1988; Blanco et al. 1993). The bris- 
tle-thighed curlew, unique among shorebirds 
because of its flightlessness during molt (Marks 
1993), is threatened by problems associated 
with increasing human populations on winter- 
ing grounds in Oceania, including the introduc- 
tion of mammalian predators (Marks et al. 
1990; Gill and Redmond 1992). 




Surfbirds (Aphiza virgata) and 
black turnstones (Arcnaria 
mckmocephala). 



In long-term studies of shorebirds nesting at 
Prudhoe Bay on Alaska's North Slope between 
1981 and 1992, considerable annual variation in 
nesting density and nest success has been found 
in several species of shorebirds (D. Troy, Troy 
Ecological Associates and British Petroleum 
Exploration, unpublished report). Much of this 
variation has been attributed to predation and 
environmental factors such as snow cover and 
temperature at the start of the breeding season. 



However, among eight species of intensively 
monitored shorebirds, only dunlin (Calidris 
alpina articola) have exhibited a general, but 
not significant, downward trend in nesting den- 
sity over this 10-year period. 

Detecting Future Trends 

To conserve the tremendous biodiversity of 
our shorebird resources in western North 
America, we suggest a two-tiered monitoring 
program that addresses trends in both habitat 
availability and shorebird population size. In 
this program we should: 

• Identify and map the current geographic extent 
and quality of breeding, staging, and wintering 
habitats important to shorebirds. particularly 
those species with relatively small populations or 
restricted habitat requirements; 

• Monitor the extent and quality of these habitats, 
evaluating them at periodic intervals; 

• Develop cooperative, international programs to 
monitor trends in shorebird populations; 

• Monitor a representative sample of shorebird 
populations and evaluate trends in comparison 
with changes in critical habitats; and 

• Establish cooperative, international agreements to 
protect critical breeding, staging, and wintering 
habitats, with priority given to those species with 
low numbers, specific habitat requirements, and 
immediate threats. 

Recently developed technology and conti- 
nental habitat mapping now provide the tools to 
identify and map the current extent of wetlands 
and other habitats important to shorebirds of 
western North America. By coupling this with 
current information on shorebird distribution 
and habitat requirements, we will be able to 
identify areas critical for shorebirds. The same 
technology can be used to monitor changes in 
these habitats over time. 

Several existing programs can be adapted or 
modified to provide reliable information on 
trends in size of several shorebird populations. 
Each species needs to be evaluated individually 
to determine where it could be monitored most 
cost-effectively — breeding grounds, staging 
areas, or wintering grounds. Programs such as 
the International Shorebird Survey, Breeding 
Bird Survey, and Christmas Bird Count can be 
used to coordinate efforts of large numbers of 
volunteers to simultaneously collect informa- 
tion on several species of shorebirds. For many 
other species like the snowy plover, buff-breast- 
ed sandpiper, and bristle-thighed curlew — of 
particular concern or difficult to monitor with 
these programs — specific surveys need to be 
designed and repeated periodically to effective- 
ly monitor population trends. 



Our Living Resources — Birds 



65 



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Bailey, R.G. 1978. Description of the ecoregions of the 
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Blanco, D., R. Banchs, P. Canevari, and M. Oesterheld. 
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Bucher, E.H., andM. Nores. 1988. Present status of birds in 
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For further information: 

Robert E. Gill. Jr. 

National Biological Service 

Alaska Science Center 

1011 E. Tudor Rd. 
Anchorage, AK 99503 



Raptors, or birds of prey, which include the 
hawks, falcons, eagles, vultures, and owls, 
occur throughout North American ecosystems. 
As predators, most of them kill other verte- 
brates for their food. Compared to most other 
animal groups, birds of prey naturally exist at 
relatively low population levels and are widely 
dispersed within their habitats. The natural 
scarcity of raptors, combined with their ability 



to move quickly, the secretive behavior of many 
species, and the difficulties of detecting them in 
rugged terrain or vegetation, all make determin- 
ing their population status difficult. 

As top predators, raptors are key species for 
our understanding and conservation of ecosys- 
tems. Changes in raptor status can reflect 
changes in the availability of their prey species, 
including population declines of mammals. 



Raptors 



by 

Mark R. Fuller 

Charles J. Henny 

Petra Boliall Wood 

National Biological Service 



66 



Birds — Our Living Resources 



Northern goshawk (Accipiter gen- 
tilis) in adult plumage, is an exam- 
ple of a raptor species for which 
there is concern about status. 



birds, reptiles, amphibians, and insects. 
Changes in raptor status also can be indicators 
of more subtle detrimental environmental 
changes such as chemical contamination and 
the occurrence of toxic levels of heavy metals 
(e.g., mercury, lead). Consequently, determin- 
ing and monitoring the population status of rap- 
tors are necessary steps in the wise management 
of our natural resources. 

Methods 

We did not compile summary statistics or 
analyze data for any species; rather, we only 
have summarized the interpretations and analy- 
ses of others. Our summary of raptor status 
draws largely on the biological literature and on 
state and federal government reports. Much of 
this information is summarized in Johnsgard 
(1988), Palmer (1988), and White (1994) and in 
proceedings sponsored by the National Wildlife 
Federation (NWF 1988, 1989a, 1989b, 1990, 
1991). Other information is from unpublished 
data (S.W. Hoffman, HawkWatch International; 
J.C. Bednarz, Arkansas State University; and 
W.R. DeRagon, U.S. Army Corps of 
Engineers). 

Interpretations and analyses to determine 
raptor status and trends can be characterized in 
four general types: impressions of biologists 
and of other serious observers of wildlife; 
impressions or nonstatistical analyses of orga- 
nized searches or of tallies of birds seen (e.g., 
Christmas Bird Counts); statistical analyses of 
intensive quantitative status surveys; and statis- 
tical analyses of standardized counts, incorpo- 
rating estimates of the survey effort (e.g., num- 
ber of persons, time expended, area covered). 

Our conclusion about the status of each 
species (Table) is usually applied on a nation- 
wide scale, but often must be qualified because 
of local or regional concerns. These reflect 




habitat modification or contamination for which 
we did not have information on a broader scale. 
We used statistical results when available, but 
usually our conclusions are based on impres- 
sions or qualitative analyses because only that is 
available on a scale across the species' range, or 
the United States. 

Selected Species 

Ospreys 

Nesting ospreys {Pandion haliaetus) are con- 
centrated along the Atlantic coast. Great Lakes, 
the northern Rocky Mountains, and in the 
Pacific Northwest. Most regional populations 
declined through the early 1970"s, but the mag- 
nitude of decline varied, with the North Atlantic 
coast and Great Lakes being most severe. After 
the 1972 nationwide ban of the insecticide DDT. 
raptor productivity improved and population 
numbers increased in most areas. Ospreys also 
benefited from reservoir construction, especially 
in the West. Osprey numbers generally are sta- 
ble, but in some areas they are still increasing. 
The large stick nests of ospreys, like those of 
bald eagles {Haliaeetus leucocephalus), are rel- 
atively conspicuous, thus aiding counts of occu- 
pied nests, which are used as a measure of pop- 
ulation size. Counts from most states in the early 
1980's provided an estimate of about 8.000 nest- 
ing pairs. Also, because several osprey popula- 
tions were studied for many years, a general 
knowledge of their population dynamics permits 
a greater understanding of this species' status. 

Snail Kite 

The endangered snail kite {Rostrhamus 

sociabilis) breeds in central and southern 
Florida, the northern extent of the species' 
range, where it is associated with wetlands that 
are affected by management of water levels. 
From 1900 to 1960 the population declined; 
however, it then increased, and now remains 
stable with fluctuations from 300 to 800 birds 
(R.E. Bennetts, University of Florida, personal 
communication). 

Bald Eagles 

Many local bald eagle populations showed 
sharp declines (25% to 100%) from 1950 to the 
1970's. Populations were adversely affected by 
shooting, habitat destruction, and organochlo- 
rine pesticides (primarily DDT). The bird was 
protected by the Bald Eagle Protection Act of 
1940. In 1978 it was reclassified as endangered 
in 43 states and threatened in 5. With the docu- 
mented effects of DDT on reproduction, early 
studies emphasized locating breeding pairs and 
monitoring reproductive success. 



Our Living Resources — Birds 



67 



After the nationwide ban of DDT in 1972, 
bald eagle reproduction improved and popula- 
tions began increasing. In 1981 about 1,300 
pairs nested in the United States outside Alaska. 
The active protection of nesting habitat and 
release of hand-reared eagles aided the popula- 
tion increase. In 1993 at least 4,016 pairs of 
bald eagles nested in the contiguous United 
States, with an estimated additional 20,000- 
25,000 pairs in Alaska. Bald eagles nesting 
along the shorelines of Lakes Superior, 
Michigan, Huron, and Erie have lower repro- 
ductive rates and relatively high concentrations 
of the toxic DDE and PCB compounds 
(Bowerman 1993). Bald eagles nesting in 
Maine also have low reproductive success, 
probably because of environmental contami- 
nants. 

Habitat loss remains a threat in many areas. 
Historically there was a continuous (though 
scattered) distribution of bald eagles in the 
Southwest, south into Sonora and Baja 
California, Mexico, where now only a remnant 
population exists. Because population increases 
were not uniform throughout the range, the U.S. 
Fish and Wildlife Service has proposed down- 
listing this species from endangered to threat- 
ened in certain geographic areas. 

Hawks 

Populations of sharp-shinned hawks 
{Accipiter striatus) in the Midwest might be 
increasing, but analyses of eastern hawk migra- 
tion count stations reveal a drop in numbers of 
juveniles, and blood samples collected from 
sharp-shinned hawks in the Northeast contained 
high DDE pesticide concentrations. Many other 
factors could be involved in a population 
decline, however. The sharp-shinned hawk pro- 
vides an example of how monitoring can warn 
researchers of a potential, long-term decline in 
a regional population. 

Similarly, the northern goshawk (A. gentilis) 
counts of eastern migrants suggest a stable pop- 
ulation, but analyses of counts from the West 
reveal a decline. There is no widespread stan- 
dardized design for surveying goshawks during 
the breeding season. 

Habitat loss has reduced the number of 
Harris' hawks (Parabuteo unicinctus), whose 
northern range extent is the southwestern 
United States. Searches reveal that Harris' 
hawks have been extirpated from some areas 
such as the Colorado River Valley, California 
and Arizona, and that clearing of brush for agri- 
culture likely has led to more than 50% reduc- 
tion in Texas in the winter. 

The biological status of the ferruginous hawk 
(Buteo regalis) remains uncertain because it is 
stable in some areas (e.g., Great Plains), but 
declining in other areas (e.g., half the western 



Table. Status and trends of raptors in the United States. 



Species 


Status/trend 


Comment' 


Black vulture (Coragyps atratus) 


Stable 


Population estimation difficult because of 
flocking and wide-ranging behavior, secretive 
nesting 


Turkey vulture (Catharles aura) 


Stable 




California condor (Gymnogyps californianus) 


Endangered; extirpated 
from wild, 1987 


Captive propagation and release underway 


Osprey (Pandion haliaetus) 


Increasing 


Good information 


Hook-billed kite (Chondrohierax uncinates) 


Unknown 


Extreme northern range limit 


American swallow-tailed kite (Elanoides Meatus) 


Stable 


Greatly reduced from historical range 


White-tailed kite (Elanus caerulcus) 


Increasing 


Recent range expansion 


Snail kite {Rostrhamus sociabilis) 


Endangered, stable 


Northern range limit 


Mississippi kite (Ictinia mississippiensis) 


Increasing 


Range expansion 


Bald eagle (Haliaeetus leucocephalus) 


Threatened or endan- 
gered in contiguous 
U.S.; increasing 


Status reassessment underway 


Northern harrier (Circus cyaneus) 


Stable 


Nomadic, no standard survey; local concern 


Sharp-shinned hawk (Accipiter striatus) 


Stable 


Regional differences 


Cooper's hawk (A cooperii) 


Stable 




Northern goshawk (A. gentilis) 


Unknown 


C2; petition to list A.g. laingr, threatened 


Common black hawk (Buteogallus anthracinus) 


Stable 


Limited distribution 


Harris' hawk (Parabuteo unicinctus) 


Stable 


Fragmented distribution, northern range limit 


Gray hawk (Buteo nitidus orAusturina plagiata) 


Stable 


C2; limited distribution, northern range limit 


Hawaiian hawk (B. solitarius) 


Endangered 


Difficult to survey, limited distribution 


Red-shouldered hawk (B. lineatus) 


Stable 


Local concern 


Broad-winged hawk (B. platypterus) 


Stable 


Migration count decline in 1980's 


Puerto Rican broad-winged hawk (B.p. brunnescens) Unknown 


C2; limited distribution 


Short-tailed hawk (B. brachyurus) 


Stable 


Northern range limit; about <500 birds in U.S. 


Swainson's hawk (B. swainsori) 


Unknown 


C3; local concern 


White-tailed hawk (B. albicaudatus) 


Stable 


Northern range limit, about 200-400 birds in 
U.S. 


Zone-tailed hawk (B. albonotatus) 


Stable 


Northern range limit, about 100 pairs in U.S. 


Red-tailed hawk (B. jamaicensis) 


Stable 


Local increases; Breeding Bird Survey data 


Ferruginous hawk (B. regalis) 


Unknown 


C2 


Rough-legged hawk (B. lagopus) 


Stable 




Golden eagle (Aquila chrysaetos) 


Stable 




Crested caracara (Caracara plancus) 


Unknown 


Northern range limit 


American kestrel (Falco sparverius) 


Stable 


Breeding Bird Survey data 


American kestrel, Florida (F.s. paulus) 


Declining 


C2 


Merlins (F. columbanus) 


Stable 




Aplomado falcon (F femoralis septentrionalis) 


Endangered 


Northern range limit; captive propagation 
and release underway 


American peregrine falcon (F. peregrinus anatum) 


Endangered; increasm; 


! 


Arctic peregrine falcon (F.p. tundrius) 


Threatened 


Proposed to delist 


Gyrialcon (F. rusticolus) 


Stable 




Prairie falcon (F. mexicanus) 


Stable 




Barn owls ( Tyto alba) 


Stable 


Local concern 


Flammulated owl (Otus flammeolus) 


Unknown 


Recent surveys reveal more birds, larger range 


Virgin Islands screech-owl (O. nudipes newtoni) 


Unknown 


C2; limited distribution 


Eastern screech-owl (O. asio) 


Stable 




Western screech-owl (0. kennicottii) 


Stable 




Whiskered screech-owl (0. trichopsis) 


Unknown 


Northern range limit 


Great horned owl (Bubo virgmianus) 


Stable 




Snowy owl (Nyctea scandiaca) 


Stable 


U.S. breeding, AK only 


Northern hawk owl (Surnia ulula) 


Unknown 


U.S. breeding. AK, northern Minnesota 


Northern pygmy owl (Glaucidium gnoma) 


Unknown 


Current survey efforts 


Ferruginous pygmy owl (G. brasilianum cactorum) 


Unknown 


C2; northern range limit 


Elf owl (Micrathene whitneyi) 


Unknown 


Current survey efforts 


Burrowing owl (Athene cunicularia) 


Declining 


Local concern 


Northern spotted owl (Strix o. caurina) 


Threatened 


Current survey efforts 


Mexican spotted owl (S.o. lucida) 


Threatened 


Current survey efforts 


California spotted owl (S.o. occidentalis) 


Unknown 


C2; current survey efforts 


Barred owl (S. varia) 


Stable 


Western range expansion 


Great gray owl (S. nebulosa) 


Stable 




Long-eared owl (Asio otus) 


Stable 


Local concern 


Short-eared owl (A flammeus) 


Stable 


Local concern 


Boreal owl (Aegolius funereus) 


Stable 


Population estimation difficult 


Northern saw-whet owl (A. acadicus) 


Stable 


Concern in southeast AK 



'Category 2 (C2)— Proposal to list is possibly appropriate but available data are not conclusive for threalened or endan- 
gered status. 
Category 3 (C3)— Proven more abundant or widespread than previously believed or not sublet to identifiable threat. 



68 



Birds — Our Living Resources 



The U.S. Department of the Interior has 
investigated the deaths of more than 
4,300 bald and golden eagles (Haliaeetus 
leucocephalus and Aquila chrysaetos) since 
the early 1960's as part of an ongoing effort 
to monitor causes of wildlife mortality. The 
availability of dead eagles for study depends 
on finding carcasses in fair to good condition 
and transporting them to the laboratory. 
Such opportunistic collection and the fact 
that recent technological advances have 
enhanced our diagnostic capabilities, partic- 
ularly for certain toxins, mean that results 
reported here do not necessarily reflect actu- 
al proportional causes of death for all eagles 
in the United States throughout the 30-year 
period. This type of sampling does, however, 
identify major or frequent causes of death. 
Most diagnosed deaths of eagles in our 



30- 



! Bald eagles 
Golden eagles 




Accidental Gunshot Electrocution Poisoning 
trauma 



Fig. 1. Causes of mortality of bald and golden 
eagles over the past 30 years. 




study resulted from accidental trauma, gun- 
shot, electrocution, and poisoning (Fig. 1). 
Accidental trauma, such as impacts with 
vehicles, power lines, or other structures, 
was the most frequent cause of death in both 
eagle species (23% of bald and 27% of gold- 
en). Gunshot killed about 15% of each 
species. Electrocution was twice as frequent 
in golden (25%) than in bald eagles (12%), 
probably because of the preference of gold- 
en eagles for prairie habitats and their use of 
utility poles as perches. 

Lead poisoning was diagnosed in 338 
eagles from 34 states (Fig. 2). Eagles 
become poisoned by lead after consuming 
lead shot and, occasionally, bullet fragments 
present in food items. Agricultural pesticides 
accounted for most remaining poisonings; 
organophosphorus and carbamate com- 
pounds killed 139 eagles in 25 states (Fig. 
3). Eagles are exposed to these chemicals in 
a variety of ways, often by consuming other 
animals that died of direct poisoning or from 
baits placed to deliberately kill wildlife. 

Overall, poisonings were more frequent 
in bald eagles (16%) than golden eagles 
(6%). The reasons for this are unclear, but 




Necropsy examination of a bald eagle at the 
National Wildlife Health Center. Madison, 
Wisconsin. 



may be related to factors that influence sub- 
mission of carcasses for examination or dif- 
ferences in species' preferences for agricul- 
tural, rangeland. and wetland habitats. 



For further information: 

J. Christian Franson 

National Biological Service 

National Wildlife Health Center 

6006 Schroeder Rd. 

Madison, WI 53711 





pi 4 
/ 14 

i» ( 1 
\ 9 \ 






IX 










*"U 




16 J 
/ 7 

1 / 


19 
10 I 

/ 1 ° 
4 


9 \ 

1 23 f 

22 

7l?\ 16 


43 
9 I 


12 J 


i 1 




I 10 


| 14 
J 5 


L 4 












2 Ji 










>-~^-~, 






& 


^ 














l<14\ 





\ 3 


~" 7 
14 ( 

1 


Tvi 
/ 3 




1- 




^jT> 


J 21 


-2-2 
Ki8 


15 
14 L 

/ 7 

5 


2 I 


2f\* 

> 1 m. 
7 Vr 

— / 2 

) 4\L 


7 


1 2 


~~\ 1 


yK> 



Fig. 2. Nationwide distribution of lead-poisoned eagles. 



Fig. 3. Nationwide distribution of eagle poisonings caused by 
organophosphorus and carbamate pesticides. 



Our Living Resources — Birds 



69 



states). Status determination is complicated by 
the low density of nesting birds and fluctuations 
in breeding associated with cycles of prey abun- 
dance. It remains in Category 2, i.e., possibly 
appropriate to propose to list but available data 
are not conclusive for threatened or endangered 
status. 

Falcons 

American peregrine falcon (Falco peregrinus 
anatum) populations declined as a result of con- 
tamination by DDT and other organochlorine 
pesticides. The species was extirpated as a 
breeding bird in the eastern United States and 
declared endangered elsewhere. Peregrine 
recovery has been accomplished in the eastern 
United States and supplemented in the West 
(except Alaska) by release of hundreds of pere- 
grines bred in captivity. Now several generations 
originating from released peregrines have sur- 
vived and produced young in the wild. In some 
locales (e.g., parts of California), however, 
young are still not produced at normal rates. In 
Alaska nesting numbers of the Arctic subspecies 
increased naturally, and it was downlisted to 
threatened status in 1984. Now the Artie pere- 
grine falcon is proposed for removal from the 
Endangered Species List. 

Owls 

The distribution of the ferruginous pygmy 
owl {Glaucidium brasilianum cactorum) 
extends north only into southern Arizona and 
southern Texas, and concern exists about its sta- 
tus because of the fragmentation and loss of 
deciduous riparian woodlands and remnant 
mesquite habitat. The subspecies occurring 
there, the cactus ferruginous pygmy owl, was 
elevated from Category 2 as of March 1993 and 
is being considered for listing as threatened. 

The spotted owl (Strix occidentalis) is being 
surveyed extensively and studied because the 
northern and Mexican subspecies are threat- 
ened. In the Pacific Northwest the threat to 
these owls is loss of old-growth forest, and in 
the Southwest, general loss of forest habitat. 
The attention focused on spotted owls has 
resulted in the only standardized, broad-scale 
survey of an owl species. Since 1968 the num- 
ber of known owl nesting areas in Oregon has 
increased from 27 records (9 sightings, 18 spec- 
imens) to about 2,700 separate sites known to 
be occupied by pairs or single birds sometime 
within the last 5 years (E. Forsman, U.S. Forest 
Service, personal communication). This does 
not reflect an increase in owls; rather, it reflects 
our ignorance of owl numbers and distribution, 
largely resulting from lack of survey effort. 



Conclusions 

Raptors, as top predators, naturally occur at 
low densities relative to many other organisms. 
As a group, raptors are poorly surveyed and 
there are few quantitative data with which to 
determine their population status and trends. A 
summary of our assessment of the status and 
population trends of the 60 species and sub- 
species of raptors we considered (Table) 
includes the following: 2 are declining in num- 
bers and 5 are increasing; 16 (27%) are thought 
to be stable; 19 (32%) are classified as stable, 
but this assessment is qualified because of local 
or regional concerns or poor information; the 
information for 12 (20%) is so poor that we 
could not determine their status; 7 (12%) of 
these species or subspecies are endangered or 
threatened; and 9 (15%) are in Category 2 or 3, 
reflecting recent concern that they might be 
endangered or threatened. 

We must learn more about the distribution 
and population dynamics of all our raptor 
species. With knowledge of their status and 
trends and information about their distribution 
and habitat requirements, we can avoid expen- 
sive, disruptive, last-resort management of these 
birds. With knowledge of their ecology, we can 
conserve biodiversity. 

References 

Bowerman, W.W. 1993. Regulation of bald eagles 

(Haliaeetus leucocephalus) productivity in the Great 

Lakes Basin: an ecological and toxological approach. 

Ph.D. dissertation, Michigan State University, East 

Lansing. 291 pp. 
Johnsgard, P.A. 1988. North American owls: biology and 

natural history. Smithsonian Institution Press, 

Washington, DC. 295 pp. 
NWF. 1988. Proceedings of the Southwest Raptor 

Management Symposium and Workshop. Scientific and 

Tech. Series 11, National Wildlife Federation. 

Washington, DC. 395 pp. 
NWF. 1989a. Proceedings of the Western Raptor 

Management Symposium and Workshop. Scientific and 

Tech. Series 12, National Wildlife Federation, 

Washington, DC. 320 pp. 
NWF. 1989b. Proceedings of the Northeast Raptor 

Management Symposium and Workshop. Scientific and 

Tech. Series 13, National Wildlife Federation, 

Washington, DC. 356 pp. 
NWF. 1990. Proceedings of the Southeast Raptor 

Management Symposium and Workshop. Scientific and 

Tech. Series 14, National Wildlife Federation, 

Washington, DC. 248 pp. 
NWF. 1991. Proceedings of the Midwest Raptor 

Management Symposium and Workshop. Scientific and 

Tech. Series 15. National Wildlife Federation, 

Washington, DC. 290 pp. 
Palmer, R.S., ed. 1988. Handbook of North American birds. 

Vols. 4 and 5. Yale University Press, New Haven, CT 

433 pp. and 462 pp. 
White, CM. 1994. Population trends and current status of 

selected western raptors. Studies in Avian Biology 

15:161-172. 



For further information: 

Mark R. Fuller 

National Biological Service 

Raptor Research and Technical 

Assistance Center 

3948 Development Ave. 

Boise, ID 83705 



70 



Birds — Our Living Resources 



Return of 
Wild Turkeys 



by 
James G. Dickson 
U.S. Forest Service 



The wild turkey {Meleagris gallopavo) is a 
large gallinaceous bird characterized by 
strong feet and legs adapted for walking and 
scratching, short wings adapted for short rapid 
flight, a well-developed tail, and a stout beak 
useful for pecking. These birds probably origi- 
nated some 2 to 3 million years ago in the 
Pliocene epoch. Molecular data suggest this 
genetic line diverged from pheasant-like birds 
about 1 1 million years ago. There are two 
species in the genus, the wild turkey of the 
United States, portions of southern Canada, and 
northern Mexico; and the ocellated turkey (M. 
ocellata) in the Yucatan region of southern 
Mexico, Belize, and northern Guatemala. This 
article focuses on the return of the wild turkey. 

Sources of Information 

Historical information on turkeys comes 
from documented accounts of early explorers, 
which have been summarized by Mosby and 
Handley (1943) and Schorger (1966). Recent 
national population estimates are composite fig- 
ures obtained from individual state wildlife 
management agencies. Researchers use many 
survey techniques including harvest estimates, 
brood counts, winter flock surveys, and hunter 
and landowner observations. Kennamer et al. 
(1992) recently summarized state estimates. At 
present, there is no consistent, widespread mon- 
itoring technique. 




Wild turkey {Meleagris gallopavo). 

Life History 

According to most accounts, wild turkeys 
were quite abundant at the time of European 
colonization of North America. Wild turkeys 
became a major food of these settlers as they 
moved westward across the forested eastern 
United States. Turkeys were also used for cloth- 
ing, ornamentation, and food by many Native 
American tribes. As the nation grew in the 
1800's, wild turkey numbers dwindled. The 
birds were harvested without restraint and mar- 
keted for human consumption. In addition, their 
forest habitat was cleared for agriculture and 
wood products. In the early 1900's, population 
numbers continued to decline. By 1920, wild 
turkeys were extirpated from 1 8 of the 39 states 
of their ancestral range (Mosby and Handley 
1943). 



Fig. 1. Distribution of the wild 
turkey in the United States and 
Mexico in 1989 (Stangel et al. 
1992). 




Our Living Resoura 



Buds 



71 



After the early 1900's little change occurred 
in wild turkey distribution and populations until 
after World War II when resources were direct- 
ed to restoring and managing the nation's 
wildlife populations, including the wild turkey. 
A technique that many state agencies believed 
to be promising, but did not work, was artificial 
propagation of game-farm or pen-raised 
turkeys. Turkeys raised in captivity were not 
properly imprinted on (recognition and attach- 
ment) wild hens and did not have the experience 
and survival skills necessary to live and repro- 
duce in the wild. 

Restoration through trapping wild turkeys in 
the wild and relocating them was the proper 
solution, but this technique was not easily 
accomplished with the wary bird. Development 
of the rapidly propelled cannon net, originally 
designed for capturing waterfowl, was a major 
factor in relocating large numbers of wild 
turkeys for restoration. Thousands of wild 
turkeys were captured or moved with this tech- 
nique or variations of it; in addition, drop nets 
and immobilizing drugs were used. 

Several other factors contributed to the 
return of the wild turkey: the maturing of the 
eastern forests, which had been almost elimi- 
nated; increased knowledge from research; 
spread of sound management practices; and bet- 
ter protection of new flocks vulnerable to 
poaching. 

The restoration of the wild turkey is a great 
wildlife management success story. In the early 
part of this century only tens of thousands of 
wild turkeys were found in a few remote areas. 
By 1959 the total population approached one- 
half million (Kennamer et al. 1992), and by 
1994 almost all of the forested eastern United 



States and much of the forested West had been 
restocked (Fig. 1 ), with the total population now 
probably approaching 4 million (Fig. 2). At pre- 
sent, there are viable wild turkey populations 
with hunting seasons in every state but Alaska, 
and the annual harvest exceeds one-half million 
turkeys. The state wildlife management agen- 
cies, aided by the National Wild Turkey 
Federation and supported by sportmen's dollars, 
undertook a tremendous task and achieved dra- 
matically successful results (Dickson 1992). 
Turkey hunting continues to be pursued by mil- 
lions of dedicated hunters. 

Future population expansion is expected to 
be somewhat limited. Most suitable turkey habi- 
tat has been stocked, and, generally, populations 
in these areas have already gone through their 
high-productivity phase. Population expansion 
is also limited because appropriate habitat will 
be lost as the human population expands. 

References 

Dickson. J.G.. ed. 1992. The wild turkey: biology and man- 
agement. Stackpole Books. Harrisburg. PA. 463 pp. 

Kennamer, J.E., M. Kennamer, and R. Brenneman. 1992. 
History. Pages 6-17 in J.G. Dickson, ed. The wild turkey: 
biology and management. Stackpole Books. Harrisburg, 
PA. 

Mosby, H.S.. and CO. Handley. 1943. The wild turkey in 
Virginia: its status, life history and management. 
Virginia Division of Game and Inland Fisheries, 
Richmond. P-R Project. 281 pp. 

Schorger. A.W. 1966. The wild turkey: its history and 
domestication. University of Oklahoma Press. Norman. 
625 pp. 

Stangel. P.W., J.I. Smith, and PL. Leberg. 1992. 
Systematics and population genetics. Pages 18-28 in J.G. 
Dickson, ed. The wild turkey: biology and management. 
Stackpole Books. Harrisburg. PA. 




59 70 80 86 90 
Year 

Pig. 2. Estimated U.S. wild turkey 
population, 1959-90 (from 
Kennamer et al. 1992). 



For further information: 

James G. Dickson 

U.S. Forest Service 

Wildlife Habitat Laboratory 

PO Box 7600. SFA Station 

Nacogdoches, TX 75962 



The mourning dove (Zenaida macroura) is 
one of the most widely distributed and 
abundant birds in North America (Droege and 
Sauer 1990). It is also the most important U.S. 
game bird in terms of numbers harvested. The 
U.S. fall population of mourning doves has 
been estimated to be about 475 million 
(Tomlinson et al. 1988; Tomlinson and Dunks 
1993). 

The breeding range of the mourning dove 
extends from the southern portions of the 
Canadian Provinces throughout the continental 
United States into Mexico, the islands near 
Florida and Cuba, and scattered areas in Central 
America (Aldrich 1993; Fig. 1). Although some 
mourning doves are nonmigratory, most 
migrate south to winter in the United States 
from northern California to Connecticut, south 
throughout most of Mexico and Central 
America to western Panama. 

Within the United States, three areas contain 



breeding, migrating, and wintering mourning 
dove populations that are largely independent of 
each other (Kiel 1959). In 1960 three areas were 
established as separate management units: the 
Eastern (EMU), Central (CMU), and Western 
(WMU;Fig. 1). 

The two main tools used to manage mourn- 
ing doves are an annual breeding population 
survey (known as the Mourning Dove Call- 
count Survey; Dolton 1993a, b) and harvest sur- 
veys. The Call-count Survey provides an annu- 
al index to population size as well as data for 
determining long-term trends in dove popula- 
tions. State harvest surveys and the National 
Migratory Bird Harvest Information Program, 
begun in 1992, estimate dove harvest. In addi- 
tion, recoveries from banded doves have pro- 
vided vital information for managing the 
species (Hayne 1975: Dunks et al. 1982; 
Tomlinson et al. 1988). 



Mourning 
Doves 



by 

David D. Dolton 

U.S. Fish and Wildlife Service 



72 



Birds — Our Living Resources 




Main wintering range 

Northern limit of wintering range 



Fig. 1. Breeding and wintering 
ranges of mourning doves and 
mourning dove management units 
in the United States. 



Status and Trends 

The Eastern Management Unit includes 27 
states— 30% of the U.S. land area. The 1993 
population indices were 18.3 doves heard and 
14.9 doves seen per route (Dolton 1993b; Fig. 
2). Both estimates are above the long-term trend 
estimates. Between 1966 and 1993, the popula- 
tion has been relatively stable. Dove harvest in 
the EMU was relatively constant from 1966 to 
1987, with between 27.5 million and 28.5 mil- 
lion birds taken. The latest estimate, a 1989 sur- 
vey, indicated that the harvest had dropped to 
about 26.4 million birds shot by an estimated 
1.3 million hunters (Sadler 1993). 

The Central Management Unit consists of 14 
states containing 46% of the U.S. land area. Of 
the three units, the CMU has the highest mourn- 
ing dove population index. The 1993 index for 
the unit of 23.9 doves heard per route is slight- 
ly below the long-term trend estimate (Dolton 
1993b; Fig. 2). For doves seen, the estimate of 
26.8 is also below what was expected. Even 
though there appears to be an increase in doves 
seen and a slight decrease in doves heard 
between 1966 and 1993, in statistical terms 
there is no significant trend indicated for either 
count. Although hunting pressure and harvest 
varied widely among states, dove harvest in the 
CMU generally increased between 1966 and 
1987 to an annual average of about 13.5 million 



birds. In 1989 almost 11 million doves were 
taken by about 747,000 hunters (Sadler 1993). 

The Western Management Unit comprises 
seven states and represents 24% of the land area 
in the United States. The 1993 population 
indices of 9.3 doves heard and 8.5 doves seen 
per route are slightly above their long-term 
trend estimates (Dolton 1993b; Fig. 2). 
Significant downward trends in numbers of 
doves heard and seen for the unit occurred 
between 1966 and 1993. From 1987 to 1993, 
however, a significant positive trend occurred in 
the unit although the indices were still below 
those of the 1960's. After a decline in the dove 
breeding population, dove harvest in the WMU 
declined significantly. In the early 1970's, about 
7.3 million doves were taken by an estimated 
450,000 hunters. By 1989, the harvest had 
dropped to about 4 million birds shot by about 
285,000 hunters (Sadler 1993). 

In summary, mourning dove populations in 
the EMU and CMU are relatively stable. 
Although the population of doves in the WMU 
declined from a high in the mid-1960's, it 
appears that it stabilized during the past 7-10 
years. U.S. dove harvest appears to be decreas- 
ing. The mourning dove remains an extremely 
important game bird, however, especially since 
more doves are harvested than all other migra- 
tory game birds combined. A 1991 survey indi- 
cated that the mourning dove provided about 
9.5 million days of hunting recreation for 1.9 
million people (USFWS and U.S. Bureau of 
Census 1993). 

Year-to-year population changes are normal 
and expected. Although populations are rela- 
tively stable in the Eastern and Central 
Management units, declining long-term trends 
in the past two decades are cause for concern in 
the Western Unit and in local areas elsewhere. A 
combination of factors may have been detri- 
mental to dove populations in some areas: habi- 
tat and agricultural changes including loss of 
nesting habitat through reclamation and indus- 
trial and urban development, changes in agri- 
cultural practices that may have reduced food 
sources, and possibly overharvest of doves in 
local areas. In California, for example, many 
live oak trees have been cut for wood products 
resulting in a loss of nesting habitat. 
Reclamation projects or lowered water tables 
eliminated thousands of acres of mesquite nest- 
ing habitat in Arizona. Since many doves from 
the WMU winter in Mexico during a 5- to 6- 
month period each year, agricultural changes 
there may negatively affect doves. 

In the CMU, agricultural changes were eval- 
uated and compared with dove population 
trends in the eastern group of states (R.R. 
George, Texas Parks and Wildlife Department, 
unpublished data); mourning dove population 



Our Living Resources — Birds 



73 



indices appeared to be most closely correlated 
with changes in number of farms (positive) or 
farm size (negative). In addition, an analysis 
identified number of farms and acres of soy- 
beans, oats, and sorghum over time as good 
indicators of the number of doves heard. 

Early records indicate that mourning doves 
were present, although not abundant, when the 
United States was settled by colonists (Reeves 
and McCabe 1993). The resulting clearing of 
forests, introduction of new food plants, grazing 
and trampling by livestock that promoted seed- 
producing plants used by doves, and the cre- 
ation of stock ponds providing more widely dis- 
tributed drinking water in the arid West all ben- 
efited the mourning dove so that they are prob- 
ably more numerous now than in colonial times. 

These birds are quite adaptable and readily 
nest and feed in urban and rural areas. The 
mourning dove has recently even expanded its 
range northward. 

References 

Aldrich, J.W. 1993. Classification and distribution. Pages 
47-54 in T.S. Baskett, M.W. Sayre, R.E. Tomlinson, and 
R.E. Mirarchi, eds. Ecology and management of the 
mourning dove. Stackpole Books, Harrisburg, PA. 

Dolton, D.D. 1993a. The Call-count Survey: historic devel- 
opment and current procedures. Pages 233-252 in T.S. 
Baskett, M.W. Sayre, R.E. Tomlinson, and R.E. Mirarchi, 
eds. Ecology and management of the mourning dove. 
Stackpole Books, Harrisburg, PA. 

Dolton, D.D. 1993b. Mourning dove breeding population 
status, 1993. U.S. Fish and Wildlife Service. Laurel, MD. 
16 pp. 

Droege, S„ and J.R. Sauer. 1990. North American Breeding 
Bird Survey annual summary 1989. U.S. Fish and 
Wildlife Service Biological Rep. 90(8). 16 pp. 

Dunks, J.H., R.E. Tomlinson, H.M. Reeves, D.D. Dolton, 
C.E. Braun, and T.P. Zapatka. 1982. Migration, harvest, 
and population dynamics of mourning doves banded in the 
Central Management Unit, 1967-77. U.S. Fish and 
Wildlife Service Special Sci. Rep.— Wildlife 249. 128 pp. 

Hayne, D.W. 1975. Experimental increase of mourning 
dove bag limit in Eastern Management Unit, 1965-72. 
Southeastern Association of the Game and Fish 
Commissioners Tech. Bull. 2. 56 pp. 

Kiel, W. H., Jr. 1959. Mourning dove management units — a 
progress report. U.S. Fish and Wildlife Service Special 
Sci. Rep.— Wildlife 42. 24 pp. 



long-term trend 




CMU 




30 



WMU 




66 68 70 72 74 76 78 80 82 
Year 



90 92 



Reeves, H.M., and R.E. McCabe. 1993. Historical perspec- 
tive. Pages 7-46 in T.S. Baskett, M.W. Sayre, R.E. 
Tomlinson, and R.E. Mirarchi, eds. Ecology and man- 
agement of the mourning dove. Stackpole Books, 
Harrisburg, PA. 

Sadler, K.C. 1993. Mourning dove harvest. Pages 449-458 
in T.S. Baskett, M.W. Sayre, R.E. Tomlinson, and R.E. 
Mirarchi. eds. Ecology and management of the mourning 
dove. Stackpole Books, Harrisburg, PA. 

Tomlinson, R.E., D.D. Dolton, H.M. Reeves, J.D. Nichols, 
and L.A. McKibben. 1988. Migration, harvest, and pop- 
ulation characteristics of mourning doves banded in the 
Western Management Unit, 1964-77. U.S. Fish and 
Wildlife Service Tech. Rep. 13. 101 pp. 

Tomlinson, R.E., and J.H. Dunks. 1993. Population charac- 
teristics and trends in the Central Management Unit. 
Pages 305-340 in T.S. Baskett, M.W. Sayre, R.E. 
Tomlinson, and R.E. Mirarchi, eds. Ecology and man- 
agement of the mourning dove. Stackpole Books, 
Harrisburg, PA. 

USFWS and U.S. Bureau of the Census. 1993. 1991 
National survey of fishing, hunting, and wildlife-associ- 
ated recreation. U.S. Government Printing Office, 
Washington, DC. 124 pp. 



Fig. 2. Population indices of 
mourning doves in the Eastern 
(EMU). Central (CMU), and 
Western (WMU) Management 
units, 1966-93. 



For further information: 

David D. Dolton 

U.S. Fish and Wildlife Service 

Office of Migratory Bird 

Management 

II 500 American Holly Dr. 

Laurel, MD 20708 



The common raven (Corvus corax) is a large 
black passerine bird found throughout the 
northern hemisphere including western and 
northern North America. Ravens are scavengers 
that frequently feed on road-killed animals, 
large dead mammals, and human refuse. They 
kill and eat prey including rodents, lambs 
(Larsen and Dietrich 1970), birds, frogs, scorpi- 
ons, beetles, lizards, and snakes. They also feed 
on nuts, grains, fruits, and other plant matter 
(Knight and Call 1980; Heinrich 1989). Their 
recent population increase is of concern because 
ravens eat agricultural crops and animals whose 
populations may be depleted. 



Ravens are closely associated with human 
activities, frequently visiting solid-waste land- 
fills and garbage containers at parks and food 
establishments, being pests of agricultural 
crops, and nesting on many human-made struc- 
tures. In two recent surveys in the deserts of 
California (FaunaWest Wildlife Consultants 
1989; Knight and Kawashima 1993), ravens 
were more numerous in areas with more human 
influences, and were often indicators of the 
degree to which humans affect an area. 

Annual Breeding Bird Surveys (BBS) con- 
ducted nationwide by the U.S. Fish and Wildlife 
Service (USFWS) indicated that raven 



Common 
Ravens in the 
Southwestern 
United States, 
1968-92 

by 

William I. Boarman 

Kristin H. Berry 

National Biological Service 



74 



Birds — Our Living Resources 



Fig. 1. Juvenile desert tortoise 
shell found beneath an active 
raven nest. The hole in the shell 
was probably pecked open by a 
raven to eat the organs. 



populations in several parts of the country sig- 
nificantly increased during 1965-79 (Robbins et 
al. 1986). This increase concerns resource man- 
agers because ravens feed on agricultural crops 
and animal species of interest to humans. For 
instance, in the deserts of the southwestern 
United States, ravens prey on young desert tor- 
toises (Gopherus agassizii; Berry 1985; Fig. 1), 
which in the Mojave and Colorado deserts are 
listed as a threatened species by the USFWS 
(Federal Register 1990). Because of high levels 
of raven predation on tortoises, the Bureau of 
Land Management has taken action to reduce 
this predation (BLM 1990, 1994). We report 
here on a 24-year trend in raven abundance 
along roadsides in the deserts of the southwest- 
ern United States and surrounding regions, 
where increasing raven populations interest 
resource management agencies (BLM 1990; 
USFWS 1994). 




Our analysis of BBS 1968-92 data focuses 
on arid lands and neighboring habitats in 
California, Nevada, Utah, and Arizona. We used 
data from 137 39.2-km (24.5-mi) routes within 
the following BBS strata: Great Basin Desert; 
mountain highlands of Arizona; Sonoran- 
Colorado Desert; Mojave Desert; basins and 
ranges, including portions of the northern 
Mojave and Great Basin deserts; Central Valley; 
and southern California grasslands, California 
foothills (southern California routes only), and 
Los Angeles ranges combined into one (coastal 
southern California). 

Status and Trends 

Between 1968 and 1992, the latest year for 
which data were available, raven populations 
increased significantly (P < 0.01) throughout 
the study area (Fig. 2), in spite of relatively high 
variances among routes. Raven sightings 
increased 76-fold in the Central Valley of 
California, 14-fold in the Sonoran-Colorado 
Desert, and 10- fold in the Mojave Desert over 
the 24-year period. Statistically significant but 
lower increases in raven populations were expe- 



rienced in the heavily urbanized coastal south- 
ern California strata. The results for the moun- 
tain highlands stratum are questionable because 
of a low number of routes (n -1\ B. Peterjohn. 
NBS, personal communication). 

In three studies, raven numbers were highest 
along powerlines, intermediate along highways, 
and lowest in open desert areas (Austin 1971; 
FaunaWest Wildlife Consultants 1989; Knight 
and Kawashima 1993). These reports and obser- 
vations of raven use of human-based resources 
for food, water, and nesting substrate (Knight 
and Call 1980; FaunaWest Wildlife Consultants 
1989; Heinrich 1989) suggest that high raven 
populations are a result of human subsidies 
(Boarman 1993). 

Increased raven populations may be a con- 
cern for threatened and endangered species if 
increased numbers of ravens result in greater 
predation. In California alone, there are 96 
threatened or endangered species, some of 
which are or may be at risk of increased raven 
predation if raven populations continue to grow. 
On San Clemente Island, ravens are a predator 
of the endangered San Clemente Island logger- 
head shrike (Lanius ludovicianus mearnsi), and 
along coastal California they prey on endan- 
gered populations of the California least tern 
(Sterna antillarum browni; Belluomini 1991). 
The carcasses of 1 1 chuckwallas [Sauromalus 
obesus), a candidate species for listing as threat- 
ened or endangered by the USFWS, were 
recently found beneath one raven nest (personal 
observation). This finding may be a rare occur- 
rence, but if raven populations continue to 
increase, more ravens may begin to prey on 
chuckwallas. We are conducting more research 
to understand the foraging ecology and popula- 
tion biology of ravens and their effects on their 
prey populations. This research will help us 
determine how much of a threat ravens pose to 
the region's biodiversity and learn how to 
reduce these effects. 




Fig. 2. A 24-year trend in the average (mean) number of 
raven sightings within each stratum studied. 



Our Living Resources — Birds 



75 



References 

Austin, G.T. 1971. Roadside distribution of the common 
raven in the Mohave Desert. California Birds 2:98. 

Belluomini. L.A. 1991. The status of the California least 
tern at Camp Pendleton, California during the breeding 
season of 1990. Natural Resources Management Branch, 
Southwest Division Naval Facilities Engineering 
Command, San Diego, CA. 77 pp. 

Berry, K.H. 1985. Avian predation on the desert tortoise in 
California. Report to Southern California Edison, Co. 
Bureau of Land Management, Riverside, CA. 20 pp. 

BLM. 1990. Draft raven management plan for the 
California Desert Conservation Area. Bureau of Land 
Management, Riverside, CA. 59 pp. 

BLM. 1994. Environmental assessment for 1994 experi- 
mental program to shoot ravens. Bureau of Land 
Management, Riverside, CA. 8 pp. 

Boarman, W.I. 1993. When a native predator becomes a 
pest: a case study. Pages 191-206 in S.K. Majumdar, 
E.W. Miller, D.E. Baker, E.K. Brown, J.R. Pratt, and R.F. 
Schmalz. eds. Conservation and resource management. 
Pennsylvania Academy of Sciences, Easton. 

FaunaWest Wildlife Consultants. 1989. Relative abundance 
and distribution of the common raven in the deserts of 
southern California and Nevada during spring and sum- 
mer of 1989. Bureau of Land Management, Riverside, 
CA. 60 pp. 

Federal Register. 1990. Endangered and threatened wildlife 
and plants; determination of threatened status for the 
Mojave population of the desert tortoise. Federal 
Register 55:12178-12191. 

Heinrich, B. 1989. Ravens in winter. Summit Books, New 
York. 379 pp. 

Knight, R., and M. Call. 1980. The common raven. Bureau 
of Land Management Tech. Note 344. 61 pp. 

Knight, R., and J. Kawashima. 1993. Responses of raven 
and red-tailed hawk populations to linear right-of-ways. 
Journal of Wildlife Management 57:266-271. 




Larsen, K.H., and J.H. Dietrich. 1970. Reduction of a raven 
population on lambing grounds with DRC-1339. Journal 
of Wildlife Management 34:200-204. 

Robbins, C.S., D. Bystrak, and P.H. Geissler. 1986. The 
Breeding Bird Survey: its first fifteen years, 1965-1979. 
U.S. Fish and Wildlife Service Resour. Publ. 157. 196 pp. 

USFWS. 1994. Desert tortoise (Mojave population) recov- 
ery plan. U.S. Fish and Wildlife Service, Portland, OR. 
73 pp. 



Common raven (Corvus corax). 



For further information: 

William I. Boarman 

National Biological Service 

Desert Tortoise Research Project 

6221 Box Springs Blvd. 

Riverside, CA 92507 



Resident sandhill cranes formed a continuous 
population in Georgia and Florida and 
widely separated populations along the Gulf 
Coastal Plain of Texas, Louisiana, Mississippi, 
and Alabama (Figure). The Mississippi sandhill 
crane (Grus canadensis pulla) was one of the 
widely separated populations on the Coastal 
Plain that bred in pine savannas in southeastern 
Mississippi, just east of the Pascagoula River to 
areas just west of the Jackson County line, 
south to Simmons Bayou, and north to an east- 
west line 8-16 km (5-10 mi) north of 
VanCleave. 

Agricultural and industrial development 
including World War II ship building, fire sup- 




Recorded historic range 
• 1897-1931 ® 1960 



Figure. Range of Mississippi sandhill cranes. 



pression, and forestry practices destroyed much 
of the sandhill crane's habitat in Jackson 
County, Mississippi. The U.S. Fish and 
Wildlife Service (USFWS) added the 
Mississippi sandhill crane to the endangered 
species list in 1973 and established the 
Mississippi Sandhill Crane National Wildlife 
Refuge in 1974. The USFWS began captive 
breeding at the Patuxent Wildlife Research 
Center (PWRC) in 1965 to protect the sub- 
species during habitat restoration and to provide 
stock for reintroduction. 

Morphological, physiological, and genetic 
differences exist among crane subspecies 
(Aldrich 1972). Mississippi birds mature earlier 
and begin egg production about 6 weeks later 
than Florida sandhill cranes. Genetic studies 
(Dessauer et al. 1992; Jarvi et al. 1994) show a 
level of heterozygosity {see glossary) in the 
wild Mississippi population about half that in 
other sandhill cranes. As in other small popula- 
tions, cranes seem to have genetic weaknesses. 
In the captive population, for example, 17% of 
all birds die from detectable heart murmurs and 
when released to the wild, 36% with heart mur- 
mur and 83% without heart murmurs survive 
for 1 year after release. 



Mississippi 

Sandhill 

Cranes 



by 

George F. Gee 

National Biological 

Service 

Scott G. Hereford 

U.S. Fish and Wildlife 

Service 



76 



Birds — Our Living Resources 



Table 1. Estimated numbers of 
Mississippi sandhill cranes on the 
Mississippi Sandhill Crane 
National Wildlife Refuge, 1929- 
93. 



Status and Trends 

Population Decline 

In the 1800's the species was abundant 
enough for farmers to consider it a pest. 
Although population studies only started 
recently, it appears the population has been 
small for most of this century (Table 1 ). 



Year 


Wild 


Captive released 


Total 


1929 






50-100 


1949 






50+ 


1969 






50-60 


1975 




30-50 


1978 






40-50 


1979 






40-50 


1980 






50 


1981 


41 


9 


50 


1982 


41 


9 


50 


1983 


34 


9 


43 


1984 


27 


13 


40 


1985 


13 


19 


32 


1986 


23 


18 


41 


1987 


17 


16 


33 


1988 


21 


23 


44 


1989 


21 


33 


54 


1990 


24 


49 


73 


1991 


19 


73 


92 


1992 


20 


88 


108 


1993 


20 


115 


135 



Until the 1940's, the human population in 
Jackson County was small, and the remnant 
population of Mississippi sandhill cranes 
remained stable. The suitable pine savanna 
habitat shrunk from over 40,500 ha (100,000 
acres) in 1940 to 10,530 ha (26,000 acres) in the 
1960's, which were designated as critical habi- 
tat by the USFWS. The USFWS requested a 
population study in 1960 when Mississippi pro- 
posed building Interstate Highway 10 through 
the last of the crane habitat. The Nature 
Conservancy, the U.S. Department of 
Transportation, and State of Mississippi donat- 
ed land to the refuge. 

Recent Reintroductions 

The first releases of hand-reared birds failed. 
Thus, releases of Mississippi sandhills on the 
refuge during the 1980's were birds raised by 
their parents or surrogate parents. These parent- 
reared birds proved wilder than the hand-reared 
birds and adapted well to the pine savanna. 
Unfortunately, the parent-rearing technique 
reduced production and increased expenses. 

The PWRC developed a new hand-rearing 
technique that visually isolated chicks from 
humans and imprinted them on adult sandhill 
cranes in the chick-rearing area. Caretakers 
dressed in sheets to hide their human form when 
handling birds, and encounters with cranes were 
limited. Juveniles were placed in socialization 
pens in the fall to form three cohorts (parent- 



reared, hand-reared, and a mixed group). A gen- 
tle release on the refuge allowed the birds to 
leave the release pen when ready and to return 
for food for a period after release. Surprisingly, 
a greater percentage of hand-reared birds has 
survived than the parent-reared birds, although 
both groups have paired and produced fertile 
eggs. The releases increased the refuge popula- 
tion from 44 in 1988 to 135 in 1993 (Table 1). 

Status in Jackson County, Mississippi 

The population decline of the Mississippi 
sandhill crane reflects the loss of the mesic and 
hydric pine savanna once abundant in the area. 
Savannas occur on coastal terraces, elevated 
ridges, and uplands. Fire frequency and intensi- 
ty, combined with soil type and hydrology, pro- 
vide successional regulation of the savanna. 
Woody, forested communities replace the 
savanna without fire. Before ditching, the flat 
topography of the terraces allowed sheet flow of 
water across the terraces and supported exten- 
sive areas of open savanna. When the refuge 
was established, about 75% of the crane savan- 
nas had been destroyed (by residential or com- 
mercial development) or changed to one of sev- 
eral different forest types. Only 5% of the orig- 
inal savanna type that supported the cranes 
remains on the Gulf Coastal Plain. For this rea- 
son, Mississippi sandhill cranes now occur only 
on the refuge and adjacent private lands in 
southeastern Mississippi. 

The Mississippi sandhill crane population 
nests only on the 7,8 1 3-ha ( 1 9,300-acre) refuge. 
The only other large tract of remnant savanna 
that might be suitable nesting habitat exists 
southeast of the refuge on the proposed Grand 
Bay National Wildlife Refuge. Savanna used by 
the Mississippi sandhill crane exists as highly 
fragmented remnants that the refuge must man- 
age to provide nesting, foraging, and roosting 
sites (Table 2). 

Mortality and natural recruitment may also 
restrict population viability. Predation (primari- 
ly mammalian) causes high mortality during the 
first year of life. Other factors that may limit 
populations include tumors, contaminants, 
microbial pathogens, and parasites. The preva- 
lence of tumors in the wild Mississippi sandhill 
crane population far exceeds that expected in 
other birds and mammals. 



Table 2. Mississippi sandhill crane nesting sites on 
refuge, by habitat. 



Typ» of habitat 


Number 


Percentage 


Open savanna 


82 


49 


Swamp edges 


62 


38 


Pine plantations 


12 


7 


Forest edges 


8 


5 


Cleared lands 


2 


1 



Our Living Resources — Birds 



77 



Research Needs 

Research needs include assessing the effects 
of prescribed burns and other mechanical tech- 
niques on habitat restoration and crane use; 
assessing the effects of water levels, water-level 
fluctuations, and hydrology on crane nesting 
and fledging success; determining the level of 
propagation and captive release conditioning 
needed to maintain population size during 
restoration; developing genetic management to 
protect the gene pool; and determining disease 
and contaminant sources for tumors and poor 
reproductive success in captive and wild flocks. 



References 

Aldrich, J. 1972. A new subspecies of sandhill cranes from 
Mississippi. Proceedings of the Biological Society of 
Washington 85(5):63-70. 

Dessauer, H.C., G.F. Gee, and J.S. Rogers. 1992. Allozyme 
evidence for crane systematics and polymorphisms with- 
in populations of sandhill, sarus, Siberian, and whooping 
cranes. Molecular Phylogenetics and Evolution 1(4):279- 
288. 

Jarvi, S.I., G.F. Gee, M.M. Miller, and W.E. Briles. 1994. 
Detection of haplotypes of the major histocompatibility 
complex in Florida sandhill cranes. Journal of Heredity. 
In press. 



For further information: 

George F Gee 

National Biological Service 

Patuxent Environmental Science 

Center 

Laurel, MD 20708 



The piping plover (Charadrius melodus) is a 
wide-ranging, beach-nesting shorebird 
whose population viability continues to decline 
as a result of habitat loss from development and 
other human disturbance (Haig 1992). In 1985 
the species was listed as endangered in the 
Great Lakes Basin and Canada and threatened 
in the northern Great Plains and along the U.S. 
Atlantic coast. The U.S. Fish and Wildlife 
Service (USFWS) is proposing that birds in the 
northern Great Plains also be listed as endan- 
gered. 

Each year, many breeding areas are censused 
and some winter surveys are conducted. In 
1991 biologists from Canada, the United States, 
Mexico, and various Caribbean nations carried 
out a simultaneous census of piping plovers at 
all known breeding and wintering sites. Census 
goals were to establish baseline population lev- 
els for all known piping plover sites and to cen- 
sus additional potential breeding and wintering 
sites (Figure). 

Status 

This census covered 2,099 sites, resulting in 
the highest number of breeding and wintering 
piping plovers ever recorded. It will be repeated 
three or four more times over the next 15-20 
years for more accurate assessment of popula- 
tion trends. 

Winter Census 

The total number of wintering birds (3,451) 
reported constituted 63% of the breeding birds 
(5,486) counted (Tables 1, 2). Most birds (55%; 
N = 1,898) were found along the Texas coast 
where the census concentrated on birds in previ- 
ously uncensused stretches of Laguna Madre's 
back bays. The highest concentration of birds in 
local sites was also reported in Texas (Haig and 
Plissner 1993). Although the 1991 census dis- 
covered more wintering birds than had been pre- 



viously reported, a large proportion of piping 
plovers were not seen in the winter census. 

Better census efforts in Louisiana, northern 
Cuba, and on many of the smaller Caribbean 
islands may reveal additional winter sites. 
Previous reviews of their distribution did not 
indicate that birds moved farther south than the 
Caribbean (Haig and Oring 1985). Relatively 
few birds are seen on the Atlantic coast in win- 
ter, a contrast to the 36% of plovers that breed 
along the Atlantic coast. Thus, the largest gap in 
our understanding of piping plover distribution 
during winter appears to be in locating winter 
sites for Atlantic coast breeders. 

Breeding Census 

All known piping plover breeding sites were 
censused in 1991 (Table 2). Piping plovers were 
widely distributed in small populations across 
their breeding range (Figure); most adults 
(63.2%) bred in the northern Great Plains and 
prairies of the United States and Canada. Thirty- 
six percent were found on the Atlantic coast and 



Piping Plovers 



by 

Susan Haig 

National Biological Service 

Jonathan H. Plissner 

University of Georgia 

Editor's note: This paper is largely a 
synopsis of a paper by Haig and Plissner 
(1993) in Condor. 




Breeding 


No. of 


Winter 


census 


birds 


census 





1-10 


■ 


O 


11-50 


■ 


O 


51 -100 


■ 


O 


101 -200 


■ 


O 


201 - 300 


■ 



Figure. Distribution of piping plovers throughout the annual cycle in 1991 



78 



Birds — Our Living Resources 



Table 1. Numbers of wintering 
piping plovers and sites where 
birds occurred in 1991. 



Location 


Birds 


Sites 


U.S. Atlantic 


North Carolina 


20 


7 


South Carolina 


51 


8 


Georgia 


37 


6 


Florida 


70 


9 


Total 


178 


30 


U.S. Gulf 


Florida 


481 


31 


Alabama 


12 


1 


Mississippi 


59 


7 


Louisiana 


750 


23 


Texas 


1,904 


64 


Total 


3,206 


126 


Mexico Gulf 


27 


4 


Caribbean 


Bahamas 


29 


1 


Turks and Caicos 








Cuba 


11 


1 


Jamaica 








Puerto Rico 








Cayman Islands 








Total 


40 


2 


Combined total 


3,451 


162 



less than 1% occurred on the Great Lakes. Sites 
with the highest concentrations of breeding 
birds also were found in the northern Great 
Plains (also known in Canada as the Great 
Prairie); however, each local population consist- 
ed of only a small (less than 8%) proportion of 
the total breeding population. Local populations 
were even smaller on the Atlantic coast. 

Migration Areas 

Atlantic coast piping plovers are commonly 
seen on east coast beaches during spring and fall 
migration. Migration routes of inland birds are 
poorly understood, however. Only a few occur- 
rences of piping plovers have been reported at 
seemingly appropriate inland migration sites 
such as Kirwin National Wildlife Refuge in 
Kansas, Cheyenne Bottoms Wildlife 
Management Area in Kansas, and Great Salt 
Plains National Wildlife Refuge in Oklahoma. It 
appears that inland birds may fly nonstop to gulf 
coast sites. 

Trends 

Because simultaneous, species-wide census- 
es were not conducted in the past, assessing pop- 
ulation trends is difficult. Examination of long- 
term census data at specific sites is useful in 
some cases. Most midcontinent sites that have 
been monitored for 10 years or more have expe- 
rienced a decline (Table 3). The cumulative 
effects of problems in the prairies have been 
modeled, and results indicate that piping plovers 
in the Great Plains are now declining by 7% 
annually (Ryan et al. 1993), a devastating trend 
for the species. Atlantic coast numbers remain 
stable; however, there has been unprecedented 
effort to protect piping plovers along the U.S. 
Atlantic coast. Results from previous censuses 



(Table 3) should be considered rough population 
estimates; as is true with many bird species, we 
have little information regarding the intensity of 
census efforts in those population estimates. 

Threats 

In the northern Great Plains, water-level reg- 
ulation policies on the major rivers (e.g., Platte, 
Missouri) serve as a direct source of chick mor- 
tality and an indirect source of habitat loss 
through vegetation encroachment and flooding 
(Schwalbach 1988; Sidle et al. 1992). We know 
that because 20% of northern Great Plains 
(Great Prairie) birds use river sites, loss of pro- 
ductivity on rivers such as the Missouri can 



Table 2. Piping plover breeding census. 


1991. 


Location 


Adults 


Sites where piping 
plovers occurred 


Atlantic Coast 


Canada 


New Brunswick 


203 


24 


Newfoundland 


7 


1 


Nova Scotia 


113 


34 


Prince Edward Island 


110 


20 


Quebec 


76 


11 


St. Pierre/Miquelon 


4 


2 


Canada Atlantic total 


513 


92 


U.S. 


Maine 


38 


8 


Massachusetts 


293 


50 


Rhode Island 


47 


7 


Connecticut 


67 


7 


New York 


338 


69 


New Jersey 


280 


22 


Delaware 


10 


3 


Maryland 


35 


1 


Virginia 


270 


14 


North Carolina 


86 


14 


South Carolina 


2 


1 


U.S. Atlantic total 


1,466 


196 


Atlantic total 


1,979 


288 


Great Lakes 


Duluth, MN 








Wisconsin 1 1 


Michigan 


39 


14 


Long Point, Ontario 








Great Lakes total 


40 


15 


Northern Great Plains/Prairie 


Canada Prairie 


Alberta 


180 


27 


Saskatchewan 


1,172 


71 


Manitoba 


80 


12 


Lake of Woods, Ontario 


5 


1 


Canada Prairie total 


1,437 


111 


U.S. Great Plains 


Montana 


308 


39 


North Dakota 


992 


115 


South Dakota 


293 


47 


Lake of Woods, MN 


13 


1 


Colorado 


13 


4 


Nebraska 


398 


106 


Iowa 


13 


2 • 


Kansas 








Oklahoma 








U.S. Great Plains total 


2,030 


314 


Combined totals 


Canada 


1.950 


203 


United States 


3,536 


525 


Total 


5,486 


728 



Our Living Resources — Birds 



79 



significantly affect annual productivity for the 
species. A similar threat to piping plovers occurs 
on Lake Diefenbaker in Saskatchewan, the 
largest piping plover breeding site in the world, 
where each year water levels are raised soon 
after parents have laid their clutches, resulting in 
a loss of all nests. 

Avian and mammalian predation is a problem 
throughout the species' breeding range, although 
population numbers appear to be stabilizing on 
the Atlantic coast and the Great Lakes as a result 
of using predator exclosures over nests (Rimmer 
and Deblinger 1990; Mayer and Ryan 1991; 
Melvin et al. 1992). Human disturbance contin- 
ues to be a problem on the Atlantic coast (Strauss 
1990), and in the Great Lakes, piping plovers 
may also be suffering from a lack of viable habi- 
tat (Nordstrom 1990). Comparison of food avail- 
ability at northern Great Plains sites with Great 
Lakes sites indicated lower diversity and abun- 
dance of invertebrates on the Great Lakes. 
Finally, recent evidence suggests that Great 
Lakes birds may be suffering from high levels of 
toxins (i.e., PCB's), which may be a prime factor 
in low productivity and population growth 
' (USFWS, East Lansing, Michigan, personal 
communication). 

The discovery of the high proportion of win- 
tering piping plovers on algal and sand flats has 
significant implications for future habitat pro- 
tection. Current development of these areas on 




Piping plover (Charadrius melodus). 

Laguna Madre in Texas and Mexico, increased 
dredging operations, and the continuous threat 
of oil spills in the Gulf of Mexico will result in 
serious loss of piping plover wintering habitat. 

In summary, piping plovers suffer from many 
factors that may cause their extinction in the 
next 50 years. Most devastated are the Great 
Lakes and northern Great Plains birds whose 
viability is severely threatened. Unfortunately, 
recovery is hindered by a lack of knowledge 
about the winter distribution, status of winter 
sites, adequate water-management policy in 
western breeding sites, and direct human distur- 
bance on the Atlantic coast. 



Location 


1st est. 


2nd est. 


1991 
census 


% 

Change 

1st est. 

1991 


% 
Change 


Year 


No. 


Year 


No. 


2nd est. 
1991 


Atlantic Coast 


Newfoundland 


1968 


30 


1984 


4 


7 


-72 


+75 


Cadden Beach, 
Nova Scotia 


1976 


56 


1983 


28 


20 


-64 


-29 


Maine 


1976 


48 


1982 


12 


38 


-21 


+217 


Rhode Island 


1945 


80 


1983 


20 


47 


-41 


+135 


Connecticut 


1980 


40 


1983 


34 


67 


+68 


+97 


Long Island, NY 


1939 


1,000 


1983 200 


338 


-66 


+69 


New Jersey 


1980 


118 


1983 


64 


280 


+137 


+338 


Delaware 


1978 


80 


1984 


18 


10 


-88 


-44 


Maryland 


1972 


85 


1984 


25 


35 


-59 


+40 


Great Lakes 


Michigan 


1979 


77 


1982 


14 


39 


-49 


+179 


Wisconsin 


1900 


140 


1983 


6 


1 


-99 


-83 


Northern Great Plains/Prairie 


Big Quill Lake, 
Saskatchewan 


1978 


210 


1984 


186 


151 


-28 


-19 


Chain Lakes, 
Alberta 


1976 


50 


n.a. 


n.a 


. 9 


-72 


n.a. 


Lake Manitoba, 
Manitoba 


1980 


27 


1984 


9 


3 


-89 


-67 


Lake of the 
Woods, MN 


1982 


44 


1986 


32 


13 


-70 


-59 


Niobrara River, 
NE 1978 


1981 


92 


1985 


100 


110 


+20 


+10 



Table 3. Changes in numbers of 
piping plovers at specific breeding 
areas.* 



'Sources are listed in Haig and Oring (1985) and Haig and Plissner 
(1993). 



References 

Haig, S.M. 1992. The piping plover. Pages 1-18 in A. Poole, 
P. Stettenheim, and F. Gill, ed. Birds of North America. 
American Ornithologists' Union, Washington. DC. 

Haig, S.M., and L.W. Oring. 1985. Distribution and status 
of the piping plover throughout the annual cycle. Journal 
of Field Ornithology 56:334-345. 

Haig, S.M., and J.H. Plissner. 1993. Distribution and abun- 
dance of piping plovers: results and implications of the 
1991 International Census. Condor 95:145-156. 

Mayer, P.M., and M.R. Ryan. 1991. Electric fences reduce 
mammalian predation on piping plover nests and chicks. 
Wildlife Society Bull. 19:59-62. 

Melvin. S.M.. L.H. Maclvor. and C.R. Griffin. 1992. 
Predator exclosures: a technique to reduce predation at 
piping plover nests. Wildlife Society Bull. 20:143-148. 

Nordstrom. L.H. 1990. Assessment of habitat suitability for 
reestablishment of piping plovers on the Great Lakes 
National Seashores. M.S. thesis. University of Missouri, 
Columbia. 36 pp. 

Rimmer, D.W., and R.D. Deblinger. 1990. Use of predator 
exclosures to protect piping plover nests. Journal of 
Field Ornithology 61:217-223. 

Ryan, M.R.. B.G. Root, and P.M. Mayer. 1993. Status of the 
piping plover in the Great Plains of North America: a 
demographic simulation model. Conservation Biology 
7:581-591. 

Schwalbach, M.J. 1988. Conservation of least terns and pip- 
ing plovers along the Missouri River and its major tribu- 
taries in South Dakota. M.S. thesis. South Dakota State 
University, Brookings. 43 pp. 

Sidle, J.G., D.E. Carlson, E.M. Kirsch. and J.J. Dinan. 1992. 
Flooding: mortality and habitat renewal for least terns 
and piping plovers. Colonial Waterbirds 15:132-136. 

Strauss. E. 1990. Reproductive success, life history patterns, 
and behavioral variation in a population of piping plovers 
subjected to human disturbance. Ph.D. dissertation, Tufts 
University, Boston, MA. 123 pp. 



For further information: 

Susan M. Haig 

National Biological Service 

Forest and Range Ecosystem 

Science Center 

Oregon State University 

3200 SW Jefferson Way 

Corvallis. OR 97331 



80 



Birds — Our Living Resources 



California 
Condors 



by 

Oliver H. Pattee 
National Biological Service 

Robert Mesta 
U.S. Fish and Wildlife Service 



The California condor (Gymnogyps calif orni- 
anus) is a member of the vulture family. 
With a wingspan of about 3 m (9 ft) and weigh- 
ing about 9 kg (20 lb), it spends much of its time 
in soaring flight visually seeking dead animals 
as food. The California condor has always been 
rare (Wilbur 1978; Pattee and Wilbur 1989). 
Although probably numbering in the thousands 
during the Pleistocene epoch in North America, 
its numbers likely declined dramatically with 
the extinction of most of North America's large 
mammals 10,000 years ago. Condors probably 
numbered in the hundreds and were nesting res- 
idents in British Columbia, Washington, 
Oregon, California, and Baja California around 
1800. In 1939 the condor population was esti- 
mated at 60-100 birds, and its home range was 
reduced to the mountains and foothills of 
California, south of San Francisco and north of 
Los Angeles. 

Conservation to halt the condor's decline 
included establishing the Sisquoc (1937) and 
Sespe (1947) condor sanctuaries within the Los 
Padres National Forest, obtaining fully protect- 
ed status under California Fish and Game Code 
(1953), placement on California's first state 
endangered species list (1971), and, finally, 
being listed by the federal government under 
the Endangered Species Act of 1973 (Wilbur 
1978). The success of these efforts could not be 
judged, however, because verifiable status and 
trends data did not become available until 1982. 
By using these data, we confirmed the decline 
in condor numbers over the past 50 years was 
even greater than thought. 

Population estimates before 1939 were 
based entirely on guesswork and interpretation 
of the fossil record, historical accounts, muse- 
um collections, or anecdotal observations by 
early naturalists and scholars. We believed there 
were fewer condors because they were no 
longer seen in many areas where they were once 
commonly observed. The condor's plight gener- 
ated widespread interest among conservation- 
ists to know the actual population size and its 
rate of decline. 

Koford (1953) conducted the first major life- 
history study of the California condor and pro- 
vided the first documented enumeration of the 
species. His count was based on numbers seen 
in the largest single flocks with an unspecified 
adjustment for condors not seen. Another esti- 
mate in 1965 (Miller et al. 1965) compared 
flock sizes seen in the late 1950's and early 
1960's with those reported by Koford. 

A yearly survey was begun by volunteers in 
1965 and continued through 1981 (except for 
1979). This survey used multiple observers at 
strategic sites who counted all condors seen for 
a 2-day period in October (Mallette and 




California condor (Gymnogyps calif ornianus). 

Borneman 1966; Wilbur 1980). The yearly pop- 
ulation estimates of this October survey were 
quite different from year to year and failed to 
provide any statistical measures of variability, 
although results did show a gradual downward 
trend in condor numbers. 

The annual October survey was replaced in 
1982 by a counting method (Snyder and 
Johnson 1985) using photographs of soaring 
condors to recognize differences in feather pat- 
terns. This method allowed individuals to be 
identified and counted. Although an improve- 
ment over previous techniques, this method is 
time consuming and only works when there are 
few animals. The photographic census was dis- 
continued after 1985 because all condors had 
been marked with uniquely colored and num- 
bered tags and radio transmitters. 

Trends 

Data used to determine the population size 
of California condors before 1982 (Figure) were 
biased for many reasons. Foremost was the fact 
that no surveyors could explain how they used 
the number of condors they saw to estimate how 
many condors actually existed. Nor could they 
say how sure they were of being right. 
Consequently, the severity of the decline and 
number of condors dying were grossly underes- 
timated. Because management was unaware of 
the severity of the decline and urgency of the 
crisis, critical decisions to save the condors 



Our Living Resources — Birds 



81 



were delayed. For example, the ability to recog- 
nize individuals based on methods that started 
in 1982 (Table) allowed us to realize we had lost 
five adult condors (about 30% of the wild pop- 
ulation) during winter 1984-85. Understanding 
the critical nature of this loss ultimately led to 
the decision to capture the remaining wild birds. 

As of January 1994 there were 66 birds, and 
the future of the captive population appears 
bright. The World Center for Birds of Prey in 
Boise, Idaho, became the third captive site in 
September 1993, joining the San Diego Wild 
Animal Park and the Los Angeles Zoo. The 
George Miksch Avian Research Center in 
Bartlesville, Oklahoma, is scheduled to become 
the fourth captive breeding facility in 1994. We 
expect all captive flocks to do well and contin- 
ue to increase, providing young birds for release 
in California as well as yet-to-be selected sites 
in Arizona and New Mexico. 

Timely and accurate status and trends data 
will continue to be important to the condor 
recovery program as more birds are released. 
Not only will these data be needed to monitor 
the success of the release, but also they are 
essential for identifying problems, which is 
especially critical because no known or suspect- 
ed mortality factors in California have been sig- 
nificantly reduced, much less eliminated. The 
relocation of all released California condors to a 
site near the Sisquoc Sanctuary after the death 
of the fourth bird (three lost to powerline colli- 
sions) reflects the close monitoring necessary to 
ensure that appropriate actions can be taken as 
quickly as possible. 

With the wild population consisting of only 
nine young birds with a restricted range and still 
dependent on artificial feeding stations, conven- 
tional radiotelemetry and tagging have been 
adequate. As the number of birds increase and 
their territories expand, however, conventional 
methods for monitoring and locating birds will 
be unable to fulfill the recovery program's 
needs. For the release program to succeed, we 
will need to identify and remove or avoid key 
mortality factors such as the powerline collision 
hazard at the first site. To accomplish this, we 




Year 


No. of captive No. of wild 
birds birds 


Total 


1982 




3 21 


24 


1983 




9 16 


25 


1984 




16 11 


27 


1985 




21 6 


27 


1986 




25 2 


27 


1987 




27 


27 


1988 




28 


28 


1989 




32 


32 


1990 




40 


40 


1991 




52 


52 


1992 




56 7 


63 


1993 




66 9 


75 


60 


, Koford 1 95C 






50 




* Wilbur 1980 




w 40 




4 


\ 


o 
-o 

o 

o 

o 30 

d 

20 


Miller etal 


1965\ 


A 

A \ Wilbur 1980 




Vl\__ 


October Surveys --*L/ \ \\ 
(1965-81) 


(averaged) 


10 





1 1 I 





Table. Status of the wild and cap- 
tive California condor populations, 
1982-93. 



1950 



60 



70 



90 2000 10 



Year 



will need to monitor and locate dozens of indi- 
vidual condors scattered over a million or more 
hectares. Equipment to do this exists but has not 
been modified or adequately tested for use on 
condors. Eventually a simple, inexpensive sur- 
vey procedure will be needed to track the wild 
condor population as it increases and starts 
reproducing. Developing these procedures now 
is essential. 

References 

Koford, C.B. 1953. The California condor. National 

Audubon Society Res. Rep. 4. 154 pp. 
Mallette, R.D., and J.C. Borneman. 1966. First cooperative 

survey of the California condor. California Fish and 

Game 52:185-203. 
Miller, A.H., I. McMillan, and E. McMillan. 1965. The cur- 
rent status and welfare of the California condor. National 

Audubon Society Res. Rep. 6. 61 pp. 
Pattee, O.H., and S.R. Wilbur. 1989. Turkey vulture and 

California condor. Pages 61-65 in Proceedings of the 

Western Raptor Management Symposium and 

Workshop. National Wildlife Federation, Washington, 

DC. 320 pp. 
Snyder, N.F.R., and E.V. Johnson. 1985. Photographic cen- 

susing of the 1982-1983 California condor population. 

Condor 87:1-13. 
Wilbur, S.R. 1978. The California condor, 1966-76: a look 

at its past and future. U.S. Fish and Wildlife Service 

North American Fauna 72. 136 pp. 
Wilbur, S.R. 1980. Estimating the size and trend of the 

California condor population, 1965-1978. California 

Fish and Game 66:40-48. 



Figure. Estimates of the 
California condor population, 
1945-82 (Snyder and Johnson 
1985). Used with permission from 
the Condor©. 



California condors have a wingspan of about 3 m or 9 ft. 



For further information: 

Oliver H. Pattee 

National Biological Service 

Patuxent Environmental Science 

Center 

15 10 American Holly Dr. 

Laurel, MD 20708 



82 



Birds — Our Living Resources 



Audubon's 
Crested 
Caracara in 
Florida 



by 

James N. Layne 

Archbold Biological Station 



Audubon's crested caracara 
(Caracara plancus audubonii) in 
Florida. 



Audubon's crested caracara {Caracara plan- 
cus audubonii) is a species characteristic of 
the grassland ecosystems of central Florida and 
is one of the state's most distinctive birds. The 
Florida population is threatened and widely 
separated from the main species' range, which 
extends from extreme southwestern Louisiana, 
southern Texas, and southern Arizona to the tip 
of South America, including Tierra del Fuego 
and the Falkland Islands. Another isolated pop- 
ulation occurs on Cuba and the Isle of Pines. 




The number of Florida caracaras is believed 
to have undergone a substantial decline from the 
early historic level in the 1950's and 1960's 
(Layne in press), with the total state population 
estimated at 250 in the early 1950's (Sprunt 
1954) and fewer than 100 birds in the late 
1960's (Heinzman 1970). Based on the appar- 
ent continuing decrease in its numbers, 
Florida's population of Audubon's crested 
caracara was federally listed as threatened in 
1987 (Federal Register 1987). As part of a gen- 
eral study of the life history, ecology, and 
behavior of the caracara in Florida, I monitored 
its distribution and population status from 1972 
to 1991. 

Information was obtained from road and off- 
road searches in all parts of the known range; 
systematic roadside and aerial surveys in a 
5,116-km 2 (1,975-mi 2 ) area within the core 
portion of the range; published records; muse- 
um specimens; and sighting reports from over 
500 cooperators. Logistical limitations prevent- 
ed surveying the entire potential Florida range 
thoroughly enough in any given year to obtain a 
reasonably accurate picture of the distribution 
and total population. Thus, estimates of the 
statewide distribution and numbers were based 
on records combined over 5-year periods: 1972- 
76, 1977-81, 1982-86, and 1987-91. Searches 
were most intensive from 1972 to 1981 and in 
the final period 1987-91. Because areas along 



public roads were surveyed more intensively 
than those remote from highways, there was a 
lower probability of detecting caracaras whose 
territories did not overlap roads than those 
whose territories included roads. This bias 
appeared to be at least partially compensated for 
by a tendency of caracaras to concentrate along 
highways because of the attraction of roadkills 
as a food source. 

Status and Trends 

The breeding range of Audubon's crested 
caracara in Florida (Fig. 1), based on records 
from the most recent 5 -year period of the study 
(1987-91), did not differ significantly from that 
during 1973-76 (Layne 1978). Caracaras were 
documented in 20 counties in central peninsular 
Florida, with most locations in the same 5- 
county area as in the earlier years. Counties 
with 10% or more of the 183 estimated loca- 
tions during 1987-91 included (number of loca- 
tions in parentheses) Glades (41), Highlands 
(34), Okeechobee (23), and Osceola (18). The 
data indicate no obvious change has occurred in 
the overall range or core area of the distribution 
of the caracara in Florida from that shown by 
Howell (1932). As there had been relatively lit- 
tle alteration of the natural habitats of the state 
up to that time, Howell's range map is assumed 
to reflect the early historical distribution. 

The estimated number of adult caracaras 
during 5-year intervals from 1972 to 1991 
ranged from 196 to 312 (Fig. 2). The variation 
between periods reflects differences in sam- 
pling effort rather than changes in actual num- 
bers. Thus, the adult population over the 20- 
year period appears to have been stable with a 
minimum of about 300 individuals in 150 terri- 
tories. Further evidence that the population 
remained generally stable between 1972 and 




Breeding range: 
■ Core area 

Overall limits 
• • • Range boundaries 



Mam species' range 



Fig. 1. Breeding range of Audubon's crested caracara in 
Florida based on records from 1987 to 1991; range bound- 
aries shown by Howell ( 1932). and main species' range in 
western United States. 



Our Living Resources — Birds 



83 



1991 is the similarity in adult-immature age 
ratios during this interval (Fig. 2). Although 
immatures could not be censused accurately 
because they tend to wander individually or in 
aggregrations after the break up of family 
groups, they are believed to have numbered 
between 100 and 200 in any one year, giving a 
total statewide population of 400-500. 

The estimate of the minimum adult popula- 
tion includes single adults observed in an area 
only once during a 5-year interval as represent- 
ing a pair on an established territory. Assuming 
that such individuals were actually unmated 
transients reduces the estimated adult popula- 
tion to about 230 individuals. Regardless of 
which estimate of the adult population during 
1972-91 is accepted, it is highly unlikely that 
the Florida population was reduced to fewer 
than 100 birds between 1967 and 1970 
(Heinzman 1970). 

Although the range of Audubon's crested 
caracara in Florida appears to have remained 
unchanged for the past 60 years and numbers 
have been stable over at least the past 20 years, 
the future status of the population is still of con- 
cern. Most birds occur on private ranchlands 
subject to habitat degradation or loss from 
intensification of agricultural practices or other 
development. The most immediate threat is 
large-scale conversion of native range and 
improved pasture habitats to citrus groves. 

A decline in the Florida caracara population 



within the next 10 years appears likely if citrus 
conversion and other habitat losses continue at 
the present rate. Because caracaras are relative- 
ly long-lived and strongly attached to their ter- 
ritories, residents may persist in a territory 
despite unfavorable changes, but may not be 
replaced by new individuals when they finally 
leave or die. The result may be a significant 
time lag before the effects of deleterious habitat 
changes are reflected in an actual population 
decline. The magnitude of the time lag in detec- 
tion of any trend in the Florida distribution and 
population of Audubon's crested caracara also 
will depend upon the effectiveness of future 
monitoring efforts. 

References 

Federal Register. 1987. Endangered and threatened wildlife 
and plants: threatened status for the Florida population of 
Audubon's crested caracara. Federal Register 
52(128):25229-25232. 

Heinzman, G. 1970. The caracara survey, a four year report. 
Florida Naturalist 43:149. 

Howell, A.H. 1932. Florida bird life. Florida Department of 
Game and Freshwater Fish. Tallahassee. 479 pp. 

Layne, J.N. 1978. Audubon's caracara (Caracara cheriway 
auduboni). Pages 34-36 in H.W. Kale II, ed. Birds, rare 
and endangered biota of Florida. Vol. 2. University Press 
of Florida. Gainesville. 

Layne. J.N. Audubon's crested caracara [Polyborus plancus 
audubonii). In J. A. Rodgers, H.W. Kale II, and H. Smith, 
eds. Birds, rare and endangered biota of Florida. 2nd ed. 
University Press of Florida. Gainesville. In press. 

Sprunt, A., Jr. 1954. Florida bird life. Coward-McCann, 
New York. 527 pp. 



300 



53% 



55% 



250 



.200 



150 



| 100 



50 



61% 



II 
II I 



72-76 77-81 82-86 87-91 
Year 

Fig. 2. Estimated numbers of 
adult Audubon's crested caracaras 
in Florida over 5-year intervals 
from 1972 to 1991, based on the 
assumption that localities where 
adults were recorded represent ter- 
ritories occupied by an adult pair. 
Percentage of locations that had 
immature birds versus those that 
had adults are given above bars. 



For further information: 

James N. Layne 

Archbold Biological Station 

PO Box 2057 

Lake Placid. FL 33862 



Since the arrival of Columbus in Puerto Rico, 
the Taino Indian has disappeared and the 
parrot has just barely survived (Wadsworth 
1949; Snyder et al. 1987). The Puerto Rican 
parrot (Amazona vittata) had shared its habitat 
with the peaceful Taino Indians for centuries 
before the arrival of European settlers in the 
Caribbean. 

Status and Trends 

Upon arrival of the Spanish in 1493, the 
Puerto Rican parrot lived in all major habitats of 
Puerto Rico and the adjacent smaller islands of 
Culebra, Mona, Vieques, and possibly the 
Virgin Islands (Snyder et al. 1987). Parrots 
occupied eight major climax or old-growth for- 
est types (Little and Wadsworth 1964) that cov- 
ered Puerto Rico and were interspersed only by 
small, scattered, sandy, or marshy areas near the 
coast (Snyder et al. 1987). Parrots nested in cav- 
ities of large trees that were plentiful throughout 
the forests. Fertile, moist lowland forests in the 
coastal plain as well as forested mountain val- 
leys contained much of the fruits and seeds nec- 



essary to feed a thriving parrot population. The 
forests of Puerto Rico probably supported a par- 
rot population of 100,000-1,000,000 at the end 
of the 15th century (Snyder et al. 1987; Wiley 
1991). 

Little habitat change occurred in Puerto Rico 
during the first 150 years of European settle- 
ment. By 1650 the Spanish population had 
increased to 880 (Snyder et al. 1987); parrots 
still occupied all major habitats and were plen- 
tiful (Fig. 1). During the next two centuries the 
human population soared to almost 500,000 
(Fig. 1 ), and clearing for agriculture, especially 
in the lowlands, eradicated forests in Puerto 
Rico (Wadsworth 1949). By 1836 reports by 



Humans 




Puerto Rican 
Parrots 

by 

J. Michael Meyers 

National Biological Service 



1500 



1600 



1700 1800 
Year 



1900 



2000 



Fig. 1. Population trends of 
humans and Puerto Rican parrots 
since 1500 (Snyder et al. 1987 and 
U.S. Census data; all data for the 
year 2000 are projected). 
Populations are converted to log , 
for showing trends. 



84 



Birds — Our Living Resources 



Moritz, a German naturalist, indicated that the 
Puerto Rican parrot population had begun to 
decline (Snyder et al. 1987). 

By 1900 the human population had doubled 
to a million (Fig. 1). About 76% of the land area 
of Puerto Rico had been converted from forest 
to agriculture (Snyder et al. 1987); less than 1% 
of the old-growth forest remained after more 
than 400 years of European civilization. At this 
time, the parrot population must have been low, 
but no data exist. By 1937 U.S. Forest Service 
(USFS) rangers estimated the Puerto Rican par- 
rot population at about 2,000 birds (Wadsworth 
1949). A few years later, parrots were found 
only in the Luquillo Mountains, formerly a for- 
est reserve of the Spanish Crown and now man- 
aged by the USFS. This area contained the last 
forest habitat suitable for Puerto Rican parrots. 

Population surveys of the Puerto Rican par- 
rot were not conducted until the 1950's. Early 
estimates of the parrot population in Puerto 
Rico are based on few written records and gen- 
eral observations (Snyder et al. 1987), knowl- 
edge of the parrot's biology, and extrapolation 
of population surveys conducted by 
Rodriguez- Vidal (1959). During the 1950's, 
Rodriguez- Vidal of the Puerto Rico Department 
of Agriculture and Commerce conducted the 
first extensive study of the Puerto Rican parrot. 
He reported a population of 200 Puerto Rican 
parrots by the mid- 1950's (Fig. 2). About 20 
years later the population had dwindled to 14 
individuals that inhabited an isolated rain forest 
of the Luquillo Mountains. 



Puerto Rican parrot {Amazona vit- | 
tata). B 




In 1968 Kepler, U.S. Fish and Wildlife 
Service (USFWS), organized parrot surveys by 
placing observers at strategic sites, including 
overlooks from prominent rocks, road-cuts, and 
building roofs. Snyder et al. (1987) improved 
the survey method in 1972 by constructing 10 
treetop lookouts in areas of major parrot use. 
Parrot surveys are conducted from these plat- 
forms during the breeding season and pre- and 
postbreeding season (Snyder et al. 1987). 
Observers collect information on parrot num- 
bers, directions, and their distance from the 
platform by the time of day. By 1993 this tree- 
top lookout system was expanded to 38 plat- 
forms (Vilella and Garcia 1994). 

In 1968 implementation of the Puerto Rican 
Parrot Recovery Plan began; it is a cooperative 
effort of scientists and managers of the Puerto 
Rico Department of Environmental and Natural 
Resources, USFS (Caribbean National Forest 
and International Institute of Tropical Forestry), 
USFWS Puerto Rican Parrot Field Office, and 
the National Biological Service. After the 
recovery program began, the parrot population 
increased to 47 birds by 1989 (Wiley 1980; 
Lindsey et al. 1989; Meyers et al. 1993); how- 
ever, about 50% of the population was 
destroyed by Hurricane Hugo that same year. A 
small population of 22-24 individuals remained 
in late 1989 (Fig. 2). Since then, the population 
recovered to 38-39 by early 1994 (F.J. Vilella. 
USFWS, personal communication). After the 
hurricane, the number of successful nesting 
pairs increased from a maximum of 5 to 6 pairs 
from 1991 to 1993 (Meyers et al. 1993; Vilella 
and Garcia 1994). 

Research and Management 

Puerto Rican parrots declined in relation to 
the increasing human population (Fig. 1 ). 
Conversion of forests to agriculture and loss of 
forest habitat, on which the species depended 
for food and nest cavities, was the primary 
cause for decline. Shooting parrots for food or 
protection of crops and capture for pets were 
secondary causes for decline. The remnant par- 
rot population in the Luquillo Mountains was 
further stressed when trails and roads were cre- 
ated and when human uses of the forest timber 
were encouraged in the early 1900's (Snyder et 
al. 1987). Storms before the arrival of 
Europeans probably had little effect on the par- 
rot population because the population was more 
widespread, and hurricanes tend to affect only a 
small geographic area. Severe hurricanes in 
1898, 1928, 1932, and 1989 reduced small, 
now-isolated populations even further. The 
apparent ability of the population to rebound 
after these storms is suggested by increases in 
the parrot population and in nesting pairs after 



Our Living Resources — Birds 



85 



2000 




37 50 



Fig. 2. Population trends of the Puerto Rican parrot in the 
20th century. 

Hurricane Hugo hit the island in 1989 (Meyers 
etal. 1993). 

Intense research and management strategies 
during the last 27 years have prevented the 
extinction of the Puerto Rican parrot. Much of 
the effort to rebuild the population has involved 
research and management of nesting sites 
(Wiley 1980; Snyder et al. 1987; Lindsey et al. 
1989; Wiley 1991). Predators, such as black rats 
{Rattus rattus) and pearly-eyed thrashers 
(Margarops fuscatus), have been controlled 
(Snyder et al. 1987). Bot fly (Philornis spp.) 
infestations of nestlings are still a minor prob- 
lem (Lindsey et al. 1989). Management of nests 
by fostering captive-reared young into wild 
nests, guarding nests, controlling honey bees 
(Apis mellifero), improving and maintaining 
existing nest cavities, and creating enhanced 
nesting cavities should increase the population 
of the Puerto Rican parrot (Wiley 1980; Lindsey 
et al. 1989; Wiley 1991; Lindsey 1992; Vilella 
and Garcia 1994). 

Hurricanes will continue to threaten the wild 
population of the Puerto Rican parrot. 
Researchers estimate that storms equal to the 
intensity of Hugo (sustained winds of 166 km/h 
or 104 mi/h) occur at least every 50 years in 
northeastern Puerto Rico (Scatena and Larsen 
1991). The risk of extinction caused by hurri- 
canes will be reduced by establishing a geo- 
graphically separated wild population (USFWS 
1987). 

Introduced parrots and parakeets are com- 
mon in Puerto Rico, including some of the 
genus Amazona. Monitored populations of 
these non-native birds have increased from 50% 
to 250% during 1990-93 (J.M. Meyers, 
National Biological Service, unpublished data). 
If they expand their ranges to include older 
forests, these populations may pose a threat to 
the Puerto Rican parrot by introducing diseases 



and by competing for resources. At present, 
none of the introduced Amazona populations 
are found near the Luquillo Mountains; howev- 
er, orange-fronted parakeets (Aratinga canicu- 
laris) have foraged and nested in these moun- 
tains at lower elevations (J.M. Meyers, NBS, 
unpublished data). 

As the Puerto Rican parrot population 
increases, it is possible that suitable nesting sites 
may limit population growth. Before this occurs, 
research and management should concentrate on 
increasing the wild population. The ability of the 
Puerto Rican parrot to expand its population in a 
manner similar to the exotic parrots in Puerto 
Rico, in a variety of natural and human-altered 
environments, should not be underestimated and 
may be the key to its recovery. 

References 

Lindsey, G.D. 1992. Nest guarding from observational 
blinds' strategy for improving Puerto Rican parrot nest 
success. Journal of Field Ornithology 63:466-472. 

Lindsey, G.D.. M.K. Brock, and M.H. Wilson. 1989. 
Current status of the Puerto Rican parrot conservation 
program. Pages 89-99 in Wildlife management in the 
Caribbean islands. Proceedings of the Fourth Meeting of 
Caribbean Foresters. U.S. Department of Agriculture. 
Institute of Tropical Forestry, Rio Piedras. Puerto Rico. 

Little. E.L., Jr., and F.H. Wadsworth. 1964. Common trees 
of Puerto Rico and the Virgin Islands (reprint). 
Agriculture Handbook 249. U.S. Department of 
Agriculture, Washington. DC. 556 pp. 

Meyers, J.M., F.J. Vilella. and W.C. Barrow, Jr. 1993. 
Positive effects of Hurricane Hugo: record years for 
Puerto Rican parrots nesting in the wild. Endangered 
Species Tech. Bull. 27:1.10. 

Rodriguez- Vidal, J. A. 1959. Puerto Rican parrot study. 
Monographs of the Department of Agriculture and 
Commerce 1. San Juan. Puerto Rico. 15 pp. 

Scatena, F.N., and M.C. Larsen. 1991. Physical aspects of 
Hurricane Hugo in Puerto Rico. Biotropica 23:317-323. 

Snyder, N.R.F., J.W. Wiley, and C.B. Kepler. 1987. The par- 
rots of Luquillo: natural history and conservation of the 
Puerto Rican parrot. Western Foundation of Vertebrate 
Zoology, Los Angeles, CA. 384 pp. 

USFWS. 1987. Recovery plan for the Puerto Rican parrot, 
Amazona vittata. U.S. Fish and Wildlife Service. Atlanta. 
GA. 69 pp. 

Vilella. F.J.. and E.R. Garcia. 1994. Post-hurricane manage- 
ment of the Puerto Rican parrot. In J. A. Bissonette and 
PR. Krausman, eds. International Wildlife Management 
Congress Proceedings. The Wildlife Society, 
Washington. DC. In press. 

Wadsworth, F.H. 1949. The development of the forested 
land resources of the Luquillo Mountains, Puerto Rico. 
Ph.D. dissertation. University of Michigan. Ann Arbor. 
481 pp. 

Wiley, J.W. 1980. The Puerto Rican parrot (Amazona vitta- 
ta)'- its decline and the program for its conservation. 
Pages 133-159 in R. E. Pasquier. ed. Conservation of new 
world parrots. International Council for Bird 
Preservation Tech. Publ. 1. Smithsonian Institute Press. 
Washington. DC. 

Wiley, J.W. 1991. Status and conservation of parrots and 
parakeets in the Greater Antilles. Bahama Islands, and 
Cayman Islands. Bird Conservation International 1:187- 
214. 



For further information: 

J. Michael Meyers 

National Biological Service 

Patuxent Environmental 

Science Center 

PO Box N 

Palmer, Puerto Rico 00721-0501 

USA 



86 



Birds — Our Living Resources 



Red-cockaded 
Woodpeckers 



by 

Ralph Costa 

U.S. Fish and Wildlife Service 

Joan L. Walker 

U.S. Forest Service 



Table. Number of red-cockaded 
woodpecker active clusters, by 
state and land ownership category, 
for various years between 1 990- 
94.* 



The red-cockaded woodpecker (RCW; 
Picoides borealis) is a territorial, nonmigra- 
tory, cooperative breeding species (Lennartz et 
al. 1987). Ecological requirements include habi- 
tat for relatively large home ranges (34 to about 
200 ha or 84 to about 500 acres; Connor and 
Rudolph 1991); old pine trees with red-heart 
disease for nesting and roosting (Jackson and 
Schardien 1986); and open, parklike forested 
landscapes for population expansion, dispersal 
(Connor and Rudolph 1991), and necessary 
social interactions. 

Historically, the southern pine ecosystems, 
contiguous across large areas and kept open with 
recurring fire (Christensen 1981), provided ideal 
conditions for a nearly continuous distribution 
of RCWs throughout the South. Within this 
extensive ecosystem red-cockaded woodpeckers 
were the only species to excavate cavities in liv- 
ing pine trees, thereby providing essential cavi- 
ties for other cavity-nesting birds and mammals, 
as well as some reptiles, amphibians, and inver- 
tebrates (Kappes 1993). The loss of open pine 
habitat since European settlement precipitated 
dramatic declines in the bird's population and 
led to its being listed as endangered in 1970 
(Federal Register 35:16047). 

We obtained historic RCW distribution data, 
arranged by state and county, from published 
sources (Jackson 1971; Hooper et al. 1980), and 
interviews with various red-cockaded wood- 
pecker experts. Current distribution and abun- 
dance data were obtained from natural resource 
agencies and knowledgeable biologists. Most 
records were reported between January 1993 
and March 1994, and most represent direct cen- 
sus data. Specific references are available from 
R. Costa (Table). 

Several terms are used to describe red-cock- 
aded woodpecker abundance. "Group" refers to 
birds that cooperate to rear the young from a sin- 
gle nest. It usually consists of a breeding male 
and female, and zero to four helpers, usually the 
group's male offspring from previous breeding 
seasons. For reporting purposes, single bird 







Ownership 




State 


Federal 


State 


Private 


Total 


Alabama 


150 


8 


25 


183 


Arkansas 


35 





121 


156 


Florida 


1,063 


128 


94 


1,285 


Georgia 


431 


2 


218 


651 


Kentucky 


5 








5 


Louisiana 422 


10 


73 


505 


Mississippi 


152 





22 


174 


North Carolina 


408 


162 


163 


733 


Oklahoma 





9 


1 


10 


South Carolina 


456 


39 


186 


681 


Tennessee 


1 








1 


Texas 


218 


26 


61 


305 


Virginia 








5 


5 


Total 


3,341 


384 


969 


4,694 




'For information on references, contact R. Costa. 



Red-cockaded woodpecker (Picoides borealis). 

groups (usually male) are tallied. The collection 
of cavity trees used by a group for nesting and 
roosting is the "cluster." Although single tree 
clusters do occur, typically each cluster consists 
of 2 to more than 15 cavity trees and may occu- 
py 2 to more than 4 ha (5 to more than 10 acres). 
Each group normally occupies and defends only 
one cluster. "Population" refers to the aggrega- 
tion of groups that are more distant than 29 km 
(18 mi) from the nearest group. A single isolat- 
ed group may constitute a population. 

Historical Distribution and 
Abundance 

The historical range of this species covered 
southeast Virginia to east Texas and north to por- 
tions of Tennessee, Kentucky, southeast 
Missouri, and eastern Oklahoma (Figure). The 
range included the entire longleaf pine ecosys- 
tem, but the birds also inhabited open shortleaf, 
loblolly, and Virginia pine forests, especially in 
the Ozark-Ouachita Highlands and the southern 
tip of the Appalachian Highlands. 

Red-cockaded woodpecker abundance was 
described variously as fairly common (Woodruff 
1907), locally common (Murphey 1939). com- 
mon (Chapman 1895), or abundant (Audubon 
1839). Occasional occurrences were noted for 
New Jersey (Hausman 1928), Pennsylvania 
(Gentry 1877), Maryland (Meanly 1943). and 
Ohio (Dawson and Jones 1903). 



Our Living Resources — Birds 



87 



The distribution map (Figure) displays only 
counties for which specimens or reliable sources 
can be cited. The gaps in the distribution 
undoubtedly contained red-cockaded wood- 
peckers in the past. Most counties without doc- 
umented occurrences are found in the longleaf 
pine-shortleaf pine-loblolly pine-hardwoods 
transition areas in the east gulf region (Figure), 
where richer soils and rolling topographies were 
associated with intense agriculture and inter- 
rupted fire regimes. Such areas possibly sup- 
ported smaller populations that were quickly 
lost with the forest clearing and therefore were 
never recorded. 

Status and Causes of Decline 

Red-cockaded woodpeckers survive as very 
small (1-5 groups) to large (groups of 200 or 
more) populations. There are at least small pop- 
ulations in most states with historical occur- 
rences (Table). Except for a population of about 
90 groups in southern Arkansas and northern 
Louisiana, the largest populations are found 
within the historical longleaf pine ecosystem. 
Other populations outside the longleaf pine 
range consist of fewer than 20 groups in single 
or several adjacent counties. Within the longleaf 
range, there are 4 populations with more than 
200 groups and 1 1 populations with more than 
100 groups; all but one are found on federal 
lands. The remaining longleaf pine-associated 



populations are small and isolated. Such small 
populations are threatened by adverse effects of 
demographic isolation, increased predation and 
cavity competition, and stochastic (random) nat- 
ural events such as hurricanes. 

The decline of the red-cockaded woodpecker 
coincided with the loss of the longleaf ecosys- 
tem. As forests were cleared, birds were isolated 
in forest tracts where unmerchantable trees were 
left. Aerial and ground photographs from the 
1930's show that scattered medium to large trees 
(0.4-2 per ha or 1-5 per acre) were left in many 
stands. The culled trees (undoubtedly including 
red-cockaded woodpecker cavity trees) provided 
residual nesting and foraging habitat for the 
birds. In some places these trees remain and are 
used by red-cockaded woodpeckers today. 

Since the 1950's, on lands managed for for- 
est products, the forest structure and composi- 
tion changed in conjunction with clearcutting, 
short timber rotations, conversion of longleaf 
stands to other pine species, and "clean" forestry 
practices (removal of cavity, diseased, or defec- 
tive trees). These practices eliminated much of 
the remaining red-cockaded woodpecker habi- 
tat. Additionally, aggressive fire suppression 
promoted the development of a hardwood mid- 
story in pine forests. The adverse impacts of a 
dense midstory on RCW populations are well- 
documented (Connor and Rudolph 1989; Costa 
andEscano 1989). 




Figure. Distribution of red-cock- 
aded woodpeckers by county and 
state. Most historical RCW 
records are cited from Jackson 
1971 and Hooper et al. 1980. For 
information on references, contact 
R. Costa. 



Birds — Our Living Resources 



Recent Developments and the 
Future 

The Red-cockaded Woodpecker Recovery 
Plan (USFWS 1985) specifies that rangewide 
recovery will be achieved when 15 viable popu- 
lations are established and protected by ade- 
quate habitat management programs. The recov- 
ery populations are to be distributed across the 
major physiographic provinces and within the 
major forest types that can be managed to sus- 
tain viable populations. Each recovery popula- 
tion will likely require 400 breeding pairs (or 
500 active clusters, as some clusters are occu- 
pied by single birds or contain nonbreeding 
groups) to ensure long-term population viability 
(Reed et al. 1993; Stevens, in press). At a densi- 
ty of 1 group/80-120 ha (200-300 acres; 
USFWS 1985; USFS 1993), landscapes of at 
least 40,000 ha (100,000 acres) will be needed 
to support viable populations. Most forested 
pine areas large enough to supply this habitat are 
on public, mostly federal, lands. 

With two exceptions (Hooper et al. 1991; 
USFS, Apalachicola National Forest, FL, 
unpublished data), there is no evidence that red- 
cockaded woodpecker populations can expand 
to viable levels without considerable human 
intervention. Conversely, numerous population 
extirpations have been documented (Baker 
1983; Costa and Escano 1989; Cox and Baker, 
in press). Ensuring the survival of the species, 
even in the short term (50 years), will require 
landscape-scale habitat and population manage- 
ment to provide the forest structure and compo- 
sition needed for nesting and foraging habitat 
and population expansion; and to manage limit- 
ing factors (primarily a lack of suitable cavity 
trees, cavity competition, and demographic iso- 
lation) that can extirpate small populations. Both 
strategies are part of management guidelines 
drafted by several federal land stewards (USFS 
1993; U.S. Army 1994; USFWS 1994). 

These ecosystem management plans promote 
practices that minimize landscape fragmenta- 
tion, retain suitable numbers of potential cavity 
trees well distributed throughout the landscape, 
and restore the original forest cover by planting 
the appropriate pine species. They recommend 
the use of growing-season fires to control hard- 
woods, create open forest conditions, and begin 
to restore the understory plant communities of 
the pine ecosystems. Stabilization and growth of 
small high-risk populations will be aided by cre- 
ating artificial red-cockaded woodpecker cavi- 
ties (Copeyon 1990) and translocating juvenile 
birds from stable larger populations into small 
ones (Rudolph et al. 1992). Technologies that 
minimize or eliminate predation and competi- 
tion problems are available (Carter et al. 1989). 



During the past 4-7 years, several popula- 
tions have stabilized or increased (Gaines et al.. 
in press; Richardson and Stockie, in press) as a 
result of implementing conservation biology 
principles — that is, integrating available tech- 
nology with the species' life history and ecolog- 
ical requirements. The limited number of juve- 
nile birds, however, may hinder recovery 
progress in all populations simultaneously. 

References 

Audubon, J.J. 1839. Ornithological biography. Vol. 5. A. 
and C. Black, Edinburgh. 

Baker, W.W. 1983. Decline and extirpation of a population 
of red-cockaded woodpeckers in northwest Florida. Pages 
44-45 in D.A. Wood., ed. Red-cockaded Woodpecker 
Symposium II Proceedings. Florida Game and 
Freshwater Fish Commission. Tallahassee. 

Carter, J.H., III, J.R. Walters, S.H. Everhart. and P.D. Doerr. 
1989. Restrictors for red-cockaded woodpecker cavities. 
Wildlife Society Bull. 17:68-72. 

Chapman, F.M. 1895. Handbook of birds of eastern North 
America. D. Appleton and Co.. New York. 431 pp. 

Christensen, N.L. 1981. Fire regimes in southeastern ecosys- 
tems. U.S. Forest Service Gen. Tech. Rep. WO-26: 112- 
136. 

Connor, R.N.. and DC. Rudolph. 1989. Red-cockaded 
woodpecker colony status and trends on the Angelina. 
Davy Crockett and Sabine National forests. U.S. Forest 
Service, Southern Forest Experiment Station. Res. Paper 
SO-250. 15 pp. 

Connor. R.N., and D.C. Rudolph. 1991. Forest habitat loss, 
fragmentation, and red-cockaded woodpecker popula- 
tion. Wilson Bull. 103 (3): 446-457. 

Copeyon. C.K. 1990. A technique for constructing cavities 
for the red-cockaded woodpecker. Wildlife Society Bull. 
18:303-311. 

Costa. R.. and R.E. Escano. 1989. Red-cockaded woodpeck- 
er status and management in the Southern Region in 
1986. U.S. Forest Service Southern Region Tech. Publ 
R8-TP 12.71 pp. 

Cox. J., and W.W. Baker. In press. Distribution and status of 
the red-cockaded woodpecker in Florida: 1992 update. 
Red-cockaded Woodpecker Symposium III: species 
recovery, ecology and management. Stephen F. Austin 
State University. Nacogdoches. TX. 

Dawson, W.L.. and L. Jones. 1903. The birds of Ohio. Vol. 
I. The Wheaton Publishing Co.. Columbus. OH. 671 pp. 

Gaines. G.D.. W.L. Jarvis. and K. Laves. In press. Red-cock- 
aded woodpecker management on the Savannah River 
Site: a management/research success story. Red-cockaded 
Woodpecker Symposium III: species recovery, ecology 
and management. Stephen F. Austin State University. 
Nacogdoches. TX. 

Gentry. T.G. 1877. Life-histories of birds of eastern 
Pennsylvania. Vol. 2. J.H. Choate. Salem. MA. 

Hausman, L.A. 1928. Woodpeckers, nuthatches, and creep- 
ers of New Jersey. New Jersey Agricultural Experiment 
Station Bull. 470:1-48. 

Hooper. R.G.. D.L. Krusac. and D.L. Carlson. 1991. An 
increase in a population of red-cockaded woodpeckers. 
Wildlife Society Bull. 19:277-286. 

Hooper, R.G.. L.J. Niles. R.F. Harlow, and G.W. Wood. 
1982. Home ranges of red-cockaded woodpeckers in 
coastal South Carolina. Auk 99(4):675-682. 

Hooper. R.G.. A.F. Robinson, and J. A. Jackson. 1980. The 
red-cockaded woodpecker: notes on life history and man- 
agement. U.S. Forest Service. Southeastern Area. State 
and Private Forestry, Gen. Rep. SA-GR 9. 8 pp. 

Jackson. J. A. 1971. The evolution, taxonomy, distribution, 
past populations and current status of the red-cockaded 
woodpecker. Pages 4-29 in R.L. Thompson, ed. The 



Our Living Resources — Birds 



89 



Ecology and Management of the Red-cockaded 
Woodpecker, Proceedings of a Symposium. Bureau of 
Sport Fisheries and Wildlife and Tall Timbers Research 
Station. Tallahassee, FL. 

Jackson, J. A., and B.J. Schardien. 1986. Why do red-cock- 
aded woodpeckers need old trees? Wildlife Society Bull. 
14:318-322. 

Kappes, J.J. 1993. Interspecific interactions associated with 
red-cockaded woodpecker cavities at a north Florida site. 
M.S. thesis, University of Florida, Gainesville. 75 pp. 

Lennartz, M.R., R.G. Hooper, and R.F. Harlow. 1987. 
Sociality and cooperative breeding of red-cockaded 
woodpeckers (Picoides borealis). Behavioral Ecology 
and Sociobiology 20:77-88. 

Meanly, R.M. 1943. Red-cockaded woodpecker breeding in 
Maryland. Auk 60:105. 

Murphey. E.E. 1939. Dryobates borealis (Vieillot), in A.C. 
Bent, Life histories of North American woodpeckers. 
Smithsonian Institution U.S. National Museum Bull. 
174:72-79. 

Reed, J.M., J.R. Walters, T.E. Emigh, and D.E. Seaman. 
1993. Effective population size in red-cockaded wood- 
peckers: population and model differences. Conservation 
Biology 7(2):302-308. 

Richardson, D., and J. Stockie. In press. Intensive manage- 
ment of a small red-cockaded woodpecker population at 



Noxubee National Wildlife Refuge. Red-cockaded 
Woodpecker Symposium III: Species Recovery, Ecology 
and Management. Stephen F. Austin State University, 
Nacogdoches, TX. 

Rudolph, DC, R.N. Connor, D.K. Carrie, and R.R. 
Schaefer. 1992. Experimental reintroduction of red-cock- 
aded woodpeckers. Auk 109(4):914-916. 

Stevens, E.E. In press. Population viability for red-cockaded 
woodpeckers. Red-cockaded Woodpecker Symposium 
III: Species Recovery, Ecology and Management. 
Stephen F. Austin State University, Nacogdoches, TX. 

U.S. Army. 1994. Management guidelines for the red-cock- 
aded woodpecker on army installations. U.S. Army Legal 
Services Agency, Arlington, VA. 19 pp. 

USFS. 1993. Draft environmental impact statement for the 
management of the red-cockaded woodpecker and its 
habitat on national forests in the Southern Region. U.S. 
Forest Service, Southern Region, Atlanta, GA. 460 pp. 

USFWS. 1985. Red-cockaded woodpecker recovery plan. 
U.S. Fish and Wildlife Service, Atlanta, GA. 88 pp. 

USFWS. 1994. Draft strategy and guidelines for the recov- 
ery and protection of the red-cockaded woodpecker on 
national wildlife refuges. U.S. Fish and Wildlife Service, 
Atlanta, GA. 50 pp. 

Woodruff, E.S. 1907. Some interesting records from south- 
ern Missouri. Auk 24:348-349. 



For further information: 

Ralph Costa 

U.S. Fish and Wildlife Service 

Red-cockaded Woodpecker Field 

Office 

Department of Forest Resources 

Clemson University 

261 Lehotsky Hall 

Box 341003 
Clemson, SC 29634 



The southwestern willow flycatcher 
{Empidonax traillii extimus) occurs, as its 
name implies, throughout most of the south- 
western United States (Fig. 1). It is a 
Neotropical migrant songbird, i.e., one of many 
birds that return to the United States and 
Canada to breed each spring after migrating 
south to the Neotropics (Mexico and Central 
America) to winter in milder climates. In recent 
years, there has been strong evidence of 
declines in many Neotropical migrant songbirds 
(e.g.. Finch and Stangel 1993), including the 
southwestern willow flycatcher (Federal 
Register 1993). The flycatcher appears to have 
suffered significant declines throughout its 
range, including total loss from some areas 
where it historically occurred. These declines, 
as well as the potential for continued and addi- 
tional threats, prompted the U.S. Fish and 
Wildlife Service (USFWS) to propose listing 
the southwestern willow flycatcher as an endan- 
gered species (Federal Register 1993). 

The southwestern willow flycatcher is one of 
four distinct races of willow flycatchers that 
breed in North America. All races breed in 
shrubby or woodland habitats, usually adjacent 
to, or near, surface water or saturated soil. 
Riparian areas — woodland and shrub areas 
along streams and rivers — are particularly 
favored. In fact, the southwestern willow fly- 
catcher is a riparian obligate, breeding only in 
riparian vegetation. It prefers tall, dense wil- 
lows and cottonwood habitat where dense vege- 
tation continues from ground level to the tree 
canopy. Southwestern willow flycatchers 
appear to breed in stands of the exotic and inva- 
sive tamarisk {Tamarix spp.) only at locations 



above 625 m (2,051 ft) elevation (Federal 
Register 1993), and where the tamarisk stands 
have suitable structural characteristics (Fig. 2). 
Thus, many areas dominated by tamarisk are 
not suitable flycatcher habitat. Being a riparian 
obligate, the southwestern willow flycatcher is 
particularly sensitive to the alteration and loss 
of riparian habitat (including tamarisk inva- 
sion), which is a widespread and pervasive 
problem throughout the Southwest. 

Because of the decline and precarious status 
of southwestern willow flycatchers, it is impor- 
tant to document the status of the species, where 
it occurs, how many individuals are present, and 
where they are successfully breeding. 
Information on trends is also important in man- 
aging and protecting the species. Grand Canyon 



Southwestern 
Willow 

Flycatchers in 
the Grand 
Canyon 



by 

Mark K. Sogge 
National Biological Service 




Fig. 1. Breeding distribution of the southwestern willow flycatcher. Dotted line represents areas 
where distribution is uncertain. 



90 



Birds — Our Living Resources 




Fig. 2. Southwestern willow fly- 
catcher breeding territory in 
tamarisk habitat along the 
Colorado River in the Grand 
Canyon. 



National Park, the USFWS, and the U.S. 
Bureau of Reclamation have been regularly 
monitoring the status of the southwestern wil- 
low flycatcher in the Grand Canyon since 1982. 
The National Biological Service's Colorado 
Plateau Research Station at Northern Arizona 
University has conducted this monitoring since 
1992. The Grand Canyon is one of the few areas 
with such a long record of willow flycatcher 
population data; the only others are the Santa 
Margarita and Kern rivers in southern 
California. 

Methods 

Our monitoring program involved intensive 
surveys of about 450 km (280 mi) of the 
Colorado River in Arizona between Glen 
Canyon Dam (Lake Powell) and upper Lake 
Mead. This portion of the river flows from ele- 
vation 945 m (3,100 ft) at the dam to 365 m 
( 1 ,200 ft) at Lake Mead. We walked through or 
floated along all potential southwestern willow 
flycatcher habitat patches along the river corri- 
dor and looked and listened for willow fly- 



Fig. 3. Surveyor broadcasting 
taped vocalizations and looking for 
response from willow flycatchers. 




catchers. Although willow flycatchers look very 
similar to several other flycatchers, they can be 
readily identified by their distinctive "fitz-bew" 
song. To increase the chance of detecting resi- 
dent flycatchers, we played a tape recording of 
willow flycatcher songs and calls (Fig. 3) as we 
moved through our survey areas. This technique 
usually elicits a response from any resident 
southwestern willow flycatchers that may be 
present (Tibbitts et al. 1994). We conducted sur- 
veys from May through July at about 160 habi- 
tat patches each year (1992 and 1993), and 
made repeated trips to each site (Sogge et al. 
1993). 



Status and Trends 

Surveys conducted between 1982 and 1991 
looked only at the upper 1 14 km (71 mi) of the 
river and counted primarily singing males. 
Within this same stretch, we detected only two 
singing male willow flycatchers in 1992, and 
three in 1993. These willow flycatchers were 
found only in the dense riparian habitat domi- 
nated by tamarisk, but including some willows 
along the river corridor above 860 m (2,800 ft) 
elevation. The breeding population of south- 
western willow flycatchers in the Grand 
Canyon was very low: we found only one nest 
in 1992, and only three in 1993. Worse yet, each 
of the three 1993 willow flycatcher nests was 
brood-parasitized by brown-headed cowbirds 
(Molothrus ater), and none produced young 
willow flycatchers. With such a small breeding 
population, and the potential for severe loss of 
breeding effort due to cowbirds, there is con- 
cern over the continued survival of the species 
within Grand Canyon. 

Based on comparison with past willow fly- 
catcher surveys in the Grand Canyon (river mi 
0-71; Brown 1988, 1991), willow flycatchers 
have declined since the mid-1980's (Fig. 4). 
Because we could conduct more surveys and 
our methods were more likely to detect fly- 
catchers than the pre- 1992 surveys (conducted 
without using tape playback), the population 
decline of the southwestern willow flycatcher in 
Grand Canyon may be even more dramatic than 
our data indicate. 

We did find willow flycatchers in areas of 
the river corridor where surveys had not been 
previously conducted: three in 1992 and five in 
1993. Two other willow flycatchers were also 
found during separate bird studies on the river 
corridor. These birds were found in tamarisk 
(above 530 m; 1.900 ft) or willow (below 530 
m; 1,900 ft) habitats. None of these wiHow fly- 
catchers established territories or bred, howev- 
er, and most were probably migrants simply 
passing through the area (Sogge et al. 1993). 



Our Living Resources — Birds 



91 




Fig. 4. The numbers of singing male southwestern willow 
flycatchers and flycatcher nests detected in the Grand 
Canyon (river mi to 71), 1982-93. Dotted lines represent 
years when surveys were not conducted. 

The low breeding population, historical 
declines, and potentially limited productivity in 
the Grand Canyon reflect the plight of the 
southwestern willow flycatcher throughout its 
range. Declines have been noted virtually 
everywhere the flycatcher occurs, and threats to 
its survival are widespread and immediate. As 
human activities such as urbanization, water 
diversion, agriculture, and grazing in riparian 
areas continue in the Southwest, so do the loss 
and alteration of riparian habitat. Vital winter- 
ing habitat in Mexico and Central America is 
also being lost to similar human activities. 

Brood parasitism by brown-headed cowbirds 
is another significant threat to southwestern wil- 
low flycatchers within the Grand Canyon and in 
many other areas. In fact, cowbirds may be one 
of the greatest threats in areas where breeding 
habitat is protected, such as the Grand Canyon 
and other national parks and protected areas. 
Cowbirds lay their eggs in the nests of other 
birds (the host), who subsequently abandon the 
nests or raise the cowbird chicks. Female cow- 
birds will sometimes remove or destroy host 
eggs, and cowbird chicks often monopolize the 
parental care of the hosts. Thus, cowbird para- 
sitism can reduce the number of host young pro- 
duced, and in some cases, cowbirds may be the 
only young successfully raised by the host. 
Such effects have been recorded for southwest- 
ern willow flycatchers in the Grand Canyon and 
in other areas as well (Federal Register 1993). 
Conversely, control and removal of cowbirds 
have resulted in local increases in southwestern 
willow flycatchers and other songbirds. 
Cowbird brood parasitism is related to riparian 
loss and fragmentation because cowbird para- 
sitism is highest in fragmented habitats. 

The southwestern willow flycatcher is a 
unique and valuable part of the riparian com- 
munity in the Southwest. Although recent and 
planned future surveys provide important status 
and distributional information on the flycatcher 
in the Grand Canyon and a few other areas with- 



in Arizona, there is a critical need for basic sur- 
veys and ecological research (including the 
effect of brown-headed cowbirds) on this 
species throughout most of its range, particular- 
ly in New Mexico, southern Utah, and 
Colorado. As a riparian obligate species whose 
continued existence is directly tied to the future 
of our remaining riparian habitats, its precarious 
status and historic decline help illustrate the 
need for riparian preservation and management. 
Such management is important not only for the 
southwestern willow flycatcher, but also for all 
plant and animal species that make up and 
depend on these valuable riparian areas. 




References 

Brown, B.T. 1988. Breeding ecology of a willow flycatcher 
population in Grand Canyon, Arizona. Western Birds 
19(l):25-33. 

Brown, B.T. 1991. Status of nesting willow flycatchers 
along the Colorado River from Glen Canyon Dam to 
Cardenas Creek, Arizona. U.S. Fish and Wildlife Service 
Endangered Species Rep. 20. 34 pp. 

Federal Register. 1993. Proposal to list the southwestern 
willow flycatcher as an endangered species, and to des- 
ignate critical habitat. U.S. Fish and Wildlife Service 23 
July 1993. Federal Register 58:39495-39522. 

Finch, D.M.. and P.W. Stangel. 1993. Status and manage- 
ment of Neotropical migratory birds; 1992 September 
21-25; Estes Park, CO. Gen. Tech. Rep. RM-229. U.S. 
Forest Service, Rocky Mountain Forest and Range 
Experiment Station. Fort Collins, CO. 422 pp. 

Sogge, M.K., T.J. Tibbitts, and S.J. Sferra. 1993. Status of 
the southwestern willow flycatcher along the Colorado 
River between Glen Canyon Dam and Lake Mead — 
1993. Summary report. National Park Service 
Cooperative Park Studies Unit, Northern Arizona 
University, U.S. Fish and Wildlife Service, and Arizona 
Game and Fish Department. 69 pp. 

Tibbitts, T.J., M.K. Sogge, and S.J. Sferra. 1994. A survey 
protocol for the southwestern willow flycatcher 
(Empidonax traillii extimus). National Park Service Tech. 
Rep. NPS/NAUCPRS/NRTR-94/04. 24 pp. 



Southwestern flycatcher 
(Empidonax traillii extimus). 



For further information: 

Mark K. Sogge 

National Biological Service 

Colorado Plateau Research Station 

Northern Arizona University 

Box 5614 

Flagstaff, AZ 86011 



pfe 









Mammals 



Overview 



Many mammalian popula- 
tion studies have been ini- 
tiated to determine a species' biological or eco- 
logical status because of its perceived econom- 
ic importance, its abundance, its threatened or 
endangered state, or because it is viewed as our 
competitor. As a result, data on mammalian 
populations in North America have been 
amassed by researchers, naturalists, trappers, 
farmers, and land managers for years. 

Inventory and monitoring programs that pro- 
duce data about the status and trends of mam- 
malian populations are significant for many rea- 
sons. One of the most important reasons, how- 
ever, is that as fellow members of the most 
advanced class of organisms in the animal king- 
dom, the condition of mammal populations 
most closely reflects our condition. In essence, 
mammalian species are significant biological 
indicators for assessing the overall health of 
advanced organisms in an ecosystem. 

Habitat changes, particularly those initiated 
by humans, have profoundly affected wildlife 
populations in North America. Though Native 
Americans used many wildlife species for food, 
clothing, and trade, their agricultural and land- 
use practices usually had minimal adverse 
effects on mammal populations during the pre- 
European settlement era. In general, during the 
post-Columbian era, most North American 



mammalian populations significantly declined, 
primarily because of their inability to adapt and 
compete with early European land-use practices 
and pressures. 

Habitat modification and destruction during 
the settlement of North America occurred very 
slowly initially. Advances in agriculture and 
engineering accelerated the loss or modification 
of habitats that were critical to many species in 
climax communities. These landscape transfor- 
mations often occurred before we had any 
knowledge of how these environmental changes 
would affect native flora and fauna. Habitat 
alterations were almost always economically 
driven and in the absence of land-use regula- 
tions and conservation measures many species 
were extirpated. 

In addition to rapid and sustained habitat and 
landscape changes from agricultural and silvi- 
cultural practices, other factors such as unregu- 
lated hunting and trapping, indiscriminate 
predator and pest control, and urbanization also 
contributed significantly to the decline of once- 
bountiful mammalian populations. These prac- 
tices, individually and collectively, have been 
directly correlated with the decline or extinction 
of many sensitive species. 

The turn of the century brought a new focus 
on conservation efforts in this country. 
Populations of some species, such as the white- 



by 

Science Editor 

Benjamin N. Tuggle 

U.S. Fish and Wildlife 

Service 

Chicago Illinois 

Field Office 

Barrington, Illinois 60010 



94 



Mammals — Our Living Resources 



tailed deer {Odocoileus virginianus), showed 
marked recovery after regulatory and conserva- 
tion strategies began. Ardent wildlife manage- 
ment and conservation programs, started pri- 
marily for game species, have increased our 
knowledge and understanding of species and 
habitat interactions. Conservation programs 
have also positively affected many species that 
share habitat with the target species the pro- 
grams are designed to aid. To complement these 
efforts, however, integrated regulatory legisla- 
tion and conservation policies that specifically 
help sustain nontarget species and their habitats 
are still imperative. 

The increased emphasis on the importance 
of managing for biological diversity and adopt- 
ing an ecosystem approach to management has 
enhanced our efforts to move from resource- 
management practices that are oriented to sin- 
gle species to strategies that focus on the long- 
term conservation of native populations and 
their natural habitats. Thus, an integrated and 
comprehensive inventory and monitoring pro- 



gram that coordinates data on the status and 
trends of our natural resources is critical to suc- 
cessfully manage habitats that support a diverse 
array of plant and animal species. 

This section provides knowledge on the sta- 
tus and trends of some higher vertebrate species 
that occupy some of this country's most diverse 
ecosystems. Many articles discuss historical 
and present species distribution, while others 
discuss the need for further research to fill our 
gaps of knowledge regarding the species. The 
articles cover a range of mammal species, some 
that have benefited greatly from past conserva- 
tion efforts, and others that are now threatened 
or endangered, with the effort to recover them 
just beginning. Some species have been directly 
affected by habitat loss or modification, others 
by past hunting and trapping pressures. 

We should not forget that our survival 
depends on wildlife, particularly higher verte- 
brates, nor should we forget that the status of 
wildlife populations serves as an advance indi- 
cator of overall environmental quality. 



Marine 
Mammals 



by 

Anne Kinsinger 

National Biological Service 

Summarized from National 

Oceanic and Atmospheric 

Administration (1994) 



At least 35 species of marine mammals are 
found along the U.S. Atlantic coast and in 
the Gulf of Mexico: 2 seal species, 1 manatee, 
and 32 species of whales, dolphins, and por- 
poises (see Table 1 for status of selected 
species). Seven of these species are listed as 
endangered under the Endangered Species Act 
(ESA). At least 50 species of marine mammals 
are found in U.S. Pacific waters: 1 1 species of 
seals and sea lions; walrus; polar bear; sea otter; 
and 36 species of whales, dolphins, and por- 
poises; 1 1 species are listed as endangered or 
threatened under the ESA (see Table 2 for the 
status of selected species). 



Table 1. Status of selected Atlantic and Gulf of Mexico coast species of marine mammals. 



Species and geographic area Abundance 



Status 



Trends 



Official status in 
designated U.S. waters 



Fin whale, NE U.S. 5,200 

Humpback whale, NW Atlantic 5,100(2,888-8,112) 



Northern right whale, NW 

Atlantic 

Pilot whales, NE U.S. 

Bottlenose dolphin 

NE U.S. coastal type 



350 

Unknown 



NE U.S. offshore type 

Gulf of Mexico (offshore and 

coastal types) 

Whitesided dolphin, NE U.S. 
Spotted dolphin, NE U.S. 
Harbor porpoise, Gulf of Maine 47,200 
Harbor seal, NE U.S. 26,000 

Beaked whales (six species in 
U.S. waters) 



Unknown 

10,000-13,000 

35,000-45,000 



27,600 
200 



Unknown 



Unknown 

Possibly 65% of 1850 

population 

Probably <5% of original 

number 

Unknown 

Possibly down by 50% 

1987-88 

Unknown 

Possibly down by 50% 

1987-88 

Unknown 

Unknown 

Unknown 

Unknown 

Unknown 



Unknown 
Unknown 

Unknown 
Unknown 



Endangered' 
Endangered' 

Endangered' 



Unknown Depleted' 



Unknown 

Unknown 
Unknown 
Unknown 
Increasing 



Proposed as threatened' 



Unknown 



'Endangered Species Act. 
"Marine Mammal Protection Act. 



NMFS Assessments 

The National Marine Fisheries Service 
(NMFS), an agency within the National Oceanic 
and Atmospheric Administration (NOAA), con- 
ducts research and status studies on many of 
these marine mammals under the authorities of 
the Magnuson Fisheries Conservation and 
Management Act, the Marine Mammal 
Protection Act (MMPA), and the ESA. The 
results of the status surveys include information 
required by the MMPA and the ESA on abun- 
dance (population size); status (as compared 
with historical levels or current viability); trends 
(changes in abundance); and status in U.S. 
waters. These results, published annually by 
NOAA, are the basis for this summary (NOAA 
1994). 

Estimates of abundance in U.S. waters are 
available for many, though not all, marine mam- 
mal species. Information on status and trends, 
however, is extremely limited because so little is 
known of the basic life history of many marine 
mammal species that scientists can determine 
neither status nor whether a population estimate 
represents a healthy, sustainable population. 
Moreover, long-term trends in many populations 
cannot be determined because historical popula- 
tion data are not available. 

The NMFS provides assessments for 139 
stocks (i.e., populations of species or groups of 
species that are treated together for manage- 
ment) of marine mammals; the status of 120 
stocks is unknown, and trend data are only 



Our Living Resources — Mammals 



95 



available for 19 stocks. The recently reautho- 
rized MMPA requires the NMFS to conduct 
periodic assessments of marine mammal stocks 
that occur in U.S. waters. For this reason, better 
status and trends data are likely to become 
available over the next few years. 

Abundance and status data for selected 
marine mammals are summarized in Table 1 
(Atlantic species) and Table 2 (Pacific species). 
Trend data are mixed, but a number of conser- 
vation success stories have come from marine 
mammals. The bowhead and grey whales have 
shown significant population increases, as have 
California sea lions, the northern elephant seal, 
harbor seals in California, Oregon, Washington, 
and the Northeast, and the southern sea otter. 
These increases are largely the result of prohi- 
bition of commercial whaling by the 
International Whaling Commission (IWC) and 
by protection enacted under the MMPA and 
ESA. Other marine mammal populations, such 
as the Steller sea lion and the common dolphin 
in the eastern tropical Pacific, are still declining. 
Causes of decline in marine mammal popula- 
tions include bycatch associated with commer- 
cial fishing, illegal killings, strandings, entan- 
glement, disease, ship strikes, altered food 
sources, and possibly exposure to contaminants. 

Population Trends 

Whales 

The eastern North Pacific stock of grey 
whale (Eschrichtius robustus) is rising (Fig. 1) 
and is one success story in species restoration. 
The NMFS estimates that the historical popula- 
tions of grey whales in 1896 were around 
15,000-20,000. While current population levels 
are below the estimated carrying capacity of 
24,000, they appear higher than historical levels 
and represent a substantial gain. The population 
growth rate between 1968 and 1988 was 3.3% 
per year. After 3 years of review, on 15 June 
1994, this species was removed from protection 
(delisted) under the ESA, an indication of suc- 
cessful management. 

y? • 

g 20- 

°- no data 



Table 2. Status of selected Pacific coast species of marine mammals. 




i | I I | I I | I I | I I | I I 
m 67 70 73 76 79 82 85 88 
Year 

Fig. 1. Estimated population of grey whales, 1967-90 
(NOAA 1994). 



Species and area Abundance 



Status 



Trends 



Official status in des- 
ignated U.S. waters 



Fin whale 

Humpback whale, E 

Pacific 

Northern right whale 

Bowhead whale, W. 

Arctic 

Grey whale 



935 

-1,400 



Unknown 
7,500 



20,869 (19,200- 

22,700) 



E. tropical Pacific dolphins 

NE spotted 731,000 

W/S spotted 1,298,000 

Coastal spotted 30,000 

E spinner 631,800 



Whitebelly spinner 


1,019,000 


N common 


476,300 


Central common 


406,100 


S common 


2,210,900 


Common (pooled) 


3,093,300 


Striped 


1,918,000 


Harbor porpoise 




SE Alaska 


2,052 


W Gulf of Alaska 


1,273 


N California 


10,000 


Central California 


3,806 


Inland Washington 


3,298 


Oregon/Washington 


23,701 


Hawaiian monk seal 


1,550 



Unknown 

Probably less than 15% of 

1850 population 

Unknown 

About 40% of 1848 

population size 

Recovered to historical 1845 

abundance levels 

Depleted 

Unknown 

Unknown 

Depleted, 44% of late 

1 950's population 

Unknown 

Unknown 

Unknown 

Unknown 

Unknown 

Unknown 



Unknown 
Unknown 

Unknown 

Increasing at 3.1%/yr, 

1978-88 

Increasing at 3.3%/yr, 

1968-88 

Declining 
Stable 
Stable 
Stable 

Stable 

Declining 

Stable 

Stable 

Stable 

Stable 



Endangered* 

Endangered' 

Endangered' 
Endangered' 

Removed from ESA 
listing June 1994 



Depleted" 



Declined 50% since 1950's 



California sea lion 
(CA, OR, WA) 
Harbor seal 

Alaska 

California 

Oregon/Washington 
Northern fur seal 

Pribilof Islands 

San Miguel 
Steller sea lion 
Northern Pacific 



111,016 Unknown 

Unknown 
63,000 
23,113 
45,713 



Unknown, pup counts 
declining to variable 
Increasing 10.2%/yr 
since 1983 
Increasing? 
Declining 
Increasing 
Increasing 



Endangered* 




982,000 < 40% of 1 950's population 

6,000 
1 1 6,000 < 22% of late 1 950's population 



No significant trend Depleted" 

since 1983 on St. Paul Is. 

Increasing 

Declined 73% since 1 960 Threatened* 



'Endangered Species Act. 
"Marine Mammal Protection Act. 

The bowhead whale (Balaena mysticetus) is 
an endangered species that has shown a signifi- 
cant increase since the IWC adopted new rules 
in 1980 regulating its harvest for subsistence 
purposes by Native Americans (Fig. 2). The 
total prewhaling (before the mid-1800's) popu- 
lation of the bowhead whale is believed to have 
been 12,000-18,000; NMFS estimates that by 
1900 it was probably in the low thousands. The 
current population of 7,500 is about 40% of its 
estimated 1848 population level (Table 2), more 
than 3 times the population low reached in 
1980. The bowhead whale population has been 
growing by about 3% per year since 1978. 

The endangered western North Atlantic pop- 
ulation of right whales (Eubalaena glacialis) is 
considered by NMFS to be the only northern 
hemisphere right whale population with a sig- 
nificant number of individuals, about 300-350 
animals (Table 1 ). Other stocks are considered 
virtually extinct: only five to seven sightings 
have been made in the last 25 years. Estimates 
of the pre- 18th century population are as high as 



96 



Mammals — Our Living Resources 



5 6 



Fig. 2. Actual counts of bowhead 
whales, 1978-90 (NOAA 1994). 



For further information: 

Michael Payne 

National Marine Fisheries Service 

Office of Protected Resources 

F/PR2 

1335 East-West Highway 

Silver Spring, MD 20910 




78 79 



nd nd nd nd 
H — I — I — h 
81 82 83 84 85 86 87 88 89 90 91 92 93 

Year 



10,000. NMFS believes that human influences 
such as ship strikes and net entanglements are 
affecting about 60% of the population. The 
agency notes that the annual loss of even a sin- 
gle right whale has measurable effect on the 
population, by greatly inhibiting recovery of the 
species. 

Dolphins and Porpoises 

The coastal migratory stock of Atlantic bot- 
tlenose dolphin (Tursiops truncatus) is listed as 
depleted under the MMPA (Table 1). This 
coastal stock incurred a loss of up to 50% dur- 
ing a 1987-88 die-off. Long-term trends are 
unknown, but the stock may require as many as 
50 years to recover. 

Harbor porpoises {Phocoena phocoena) 
occur on both U.S. coasts and are faring rela- 
tively well. The northwestern Atlantic harbor 
porpoise is found from Newfoundland, Canada, 
to Florida. The NMFS 1991-92 population esti- 
mate of the Gulf of Maine population is 47,200 
(Table 1 ), but estimates of abundance for other 
populations do not exist. NMFS has found that 
harbor porpoise mortality from sink gill-net 
fisheries along the east coast of North America 
from Canada to North Carolina appears large 
compared with the species' natural reproduction 
rates. Management actions are being taken to 
address this issue, but long-term trends are 
unknown. On the west coast, NMFS's com- 
bined population estimate for northern 
California, Oregon, and Washington coastal 
stocks is 45,713. 

The NMFS assesses 10 stocks of eastern 
tropical Pacific dolphins. Although population 
trends for most populations cannot be detected, 
the northeastern stocks of offshore spotted dol- 
phin and the common dolphin may be declining 
(Table 2). These two stocks, as well as the east- 
ern spinner and the striped dolphin, are inciden- 
tally taken in the international fishery for yel- 
lowfin tuna in the tropical Pacific waters off 



Mexico and Central America. Although mortali- 
ty has been reduced in recent years, populations 
are still declining, or at best not increasing. 

Seals and Sea Lions 

According to the NMFS, harbor seal (Phoca 
vitulina) populations have increased recently 
throughout much of their range because of pro- 
tection by the MMPA. Recent NMFS surveys 
estimate that at least 26,000 harbor seals inhabit 
the Gulf of Maine (Table 1). Populations of 
California harbor seals are also increasing; a 
recent survey resulted in a count of about 23,000 
harbor seals residing in the Channel Islands and 
along the California mainland (Table 2), an 
increase from about 12,000 in 1983. The popu- 
lation of harbor seals in Oregon and Washington 
has been estimated at 45,700, and is also 
increasing. Harbor seal counts in the Central 
Gulf of Alaska, however, have declined signifi- 
cantly in the past two decades; numbers are cur- 
rently estimated by NOAA at 63,000 seals. 

The northern fur seal (Callorhinus ursinus) 
is considered depleted under the MMPA. 
Production on one of its major breeding areas, 
Alaska's Pribilof Islands, dropped more than 
60% between 1955 and 1980, but has since sta- 
bilized. The current population is less than 40% 
of the mid-1950's level; no significant trend in 
the Pribilof Islands population has been noted 
since 1983 (Table 2). 

The northern sea lion or Steller sea lion 
(Eumetopias jubatus) is listed as threatened 
under the ESA. Species numbers have declined 
sharply throughout its range in the last 34 years 
(Table 2). The number of adults and juveniles in 
U.S. waters dropped from 154,000 in 1960 to 
40,000 in 1992, a reduction of 73%. Most of 
this decline occurred in Alaska waters, and is 
believed due to a combination of factors, 
including incidental kills, illegal shooting, 
changes in prey availability and biomass, and 
perhaps other unidentified factors. 

The U.S. population of California sea lions 
(Zalophus californianus) is increasing at a rate 
of about 10% annually. In 1990, NMFS esti- 
mated that the U.S. population was 111.000 
individuals (Table 2). A number of human-relat- 
ed interactions, such as incidental take during 
fishing, entanglement, illegal killing, and pollu- 
tants, result in sea lion deaths. 

Reference 

NOAA. 1994. Our living ocean: report on the status of U.S. 
living marine resources. 1993. NOAA Tech. 
Memorandum NMFS-F/SPO-15. National Oceanic and 
Atmospheric Administration, National Marine Fisheries 
Service, Silver Spring, MD. 136 pp. 



Our Living Resources — Mammals 



97 



The Indiana bat (Myotis sodalis) is an endan- 
gered species that occurs throughout much 
of the eastern United States (Fig. 1 ). Although 
bats are sometimes viewed with disdain, they 
are of considerable ecological and economic 
importance. Bats consume a diet consisting 
largely of nocturnal insects and thereby are a 
natural control for both agricultural pests and 
insects that are annoying to humans. 
Furthermore, many forms of cave life depend 
upon nutrients brought into caves by bats in the 
form of guano or feces (Missouri Department of 
Conservation 1991). 




• Priority 1 hibernacula 
□ Range of bat 



Fig. 1. Range of the Indiana bat and locations of Priority 
1 hibernacula (see text for definitions). 



Indiana bats use distinctly different habitats 
during summer and winter. In winter, bats con- 
gregate in a few large caves and mines for hiber- 
nation and have a more restricted distribution 
than at other times of the year. Nearly 85% of 
the known population winters in only seven 
caves and mines in Missouri, Indiana, and 
Kentucky, and approximately one-half of the 
population uses only two of these hibernacula. 

In spring, females migrate north from their 
hibernacula and form maternity colonies in pre- 
dominantly agricultural areas of Missouri, 
Iowa, Illinois, Indiana, and Michigan. These 
colonies, consisting of 50 to 150 adults and 
their young, normally roost under the loose bark 
of dead, large-diameter trees throughout sum- 
mer; however, living shagbark hickories {Carya 
ovata) and tree cavities are also used occasion- 
ally (Humphrey et al. 1977; Gardner et al. 1991; 
Callahan 1993; Kurta et al. 1993). 

As a consequence of their limited distribu- 
tion, specific summer and winter habitat 
requirements, and tendency to congregate in 
large numbers during winter, Indiana bats are 
particularly vulnerable to rapid population 
reductions resulting from habitat change, envi- 
ronmental contaminants, and other human dis- 
turbances (Brady et al. 1983). Additionally, 
because females produce only one young per 



year, recovery following a population reduction 
occurs slowly. Concerns arising from the high 
potential vulnerability and slow recovery rate 
have led to a long-term population monitoring 
effort for this species. 

Bat Census Design 

The first rangewide census of wintering 
Indiana bats was made in 1975. All subsequent 
population data were gathered according to 
standardized cave census techniques established 
by the Indiana Bat Recovery Team in 1983 
(Brady et al. 1983). Data presented in this arti- 
cle are based upon counts made at 2-year inter- 
vals at Priority 1 hibernacula, which are caves 
where winter populations exceeding 30,000 
bats have been recorded. We chose to use data 
only from Priority 1 caves because they contain 
the majority of bats in the population. During 
midwinter cave censuses, bats hanging singly 
and in small clusters of up to 25 were counted 
individually. The number of bats in larger clus- 
ters was determined by multiplying the surface 
area of the cluster by bat density (Fig. 2). 

Bat Populations: Trends and 
Recovery Prospects 

Before the 1970's, the population status of 
Indiana bats was poorly understood because the 
locations of many of their winter hibernacula 
were unknown, and the counts that were con- 
ducted were made irregularly and inconsistent- 
ly. The 1975 census established a benchmark of 
nearly 450,000 bats using Priority 1 hibernacu- 
la. Since 1983 the number of bats tallied has 
declined significantly, reaching a low of 
347,890 during the most recent census in 1993 
(Fig. 3). 



Indiana Bats 



by 

Ronald D. Drobney 

National Biological Service 

Richard L. Claw son 

Missouri Department of 

Conservation 




Hibernating cluster of Indiana bats. 



98 



Mammals — Our Living Resources 



"ST4- 

b 

o 

o 

o 

<=>3 



Missouri 




Kentucky 



83 85 87 89 91 93 

Year 

Fig. 3. State and national trends 
for Indiana bats, 1983-93. 



For further information: 

Ronald D. Drobney 

National Biological Service 

Missouri Cooperative Fish and 

Wildlife Research Unit 

112 Stephens Hall 
University of Missouri 
Columbia, MO 65211 



Although the national trend indicates a 22% 
decline during the past 10 years, this decrease 
has not been consistent across the species' win- 
ter range (Fig. 3). Most of the decrease in the 
10-year national census results can be account- 
ed for by a precipitous 34% decline in the num- 
ber of bats counted in Missouri. A more favor- 
able pattern has been noted in Indiana, where 
numbers have increased, and in Kentucky, 
where the population has remained relatively 
stable. 

Recovery efforts have included placing gates 
or fences across cave entrances to eliminate dis- 
turbances to hibernating bats. These exclusion 
devices have not halted population declines, 
suggesting that other factors are negatively 
influencing bat populations. 

Another potential threat is the loss of habitat 
used by maternity colonies. Maternity roost 
sites in dead trees exposed to sunlight and locat- 
ed in upland forests and near streams are partic- 
ularly important. Losses of these sites through 
streamside deforestation and stream channeliza- 
tion pose significant threats to population 
recovery. 

Pesticides and other environmental contami- 
nants represent additional hazards. Indiana bats 
are exposed to lingering residues of chlorinated 
hydrocarbon pesticides such as aldrin and hep- 
tachlor. These products have been banned since 
the 1970's, but persist in the soil and in insects 
upon which bats feed. Potential detrimental 
effects of the new generation of pesticides, 
including organophosphates, are unknown. 



The long-term prognosis for Indiana bat 
populations is uncertain. The fact that wintering 
populations appear to be increasing in Indiana 
and are remaining relatively stable in Kentucky 
provides the basis for some optimism. A better 
understanding of their summer habitat require- 
ments and factors affecting survival and repro- 
duction is needed so that more effective recov- 
ery efforts can be formulated. It is important to 
recognize, however, that even if the factors that 
are negatively influencing Indiana bat popula- 
tions are removed, recovery will occur slowly 
because this species has a low reproductive rate. 

References 

Brady, J.T., R.K. LaVal. T.H. Kunz. M.D. Tuttle. D.E. 
Wilson, and R.L. Clawson. 1983. Recovery plan for the 
Indiana bat. U.S. Fish and Wildlife Service, Washington. 
DC. 94 pp. 

Callahan, E.V. 1993. Indiana bat summer habitat require- 
ments. M.S. thesis. University of Missouri. Columbia. 74 
pp. 

Gardner, J.E., J.D. Garner, and J.E. Hofmann. 1991. 
Summer roost selection and roosting behavior of Myotis 
sodalis (Indiana bat) in Illinois. Final report. Illinois 
Natural History Survey, Illinois Department of 
Conservation, Champaign. 56 pp. 

Humphrey, S.R., A. R. Richter, and J.B. Cope. 1977. 
Summer habitat and ecology of the endangered Indiana 
bat, Myotis sodalis. Journal of Mammalogy 58:334-346. 

Kurta, A., D. King, J. A. Teramino, J.M. Stribley. and K.J. 
Williams. 1993. Summer roosts of the endangered 
Indiana bat {Myotis sodalis) on the northern edge of its 
range. American Midland Naturalist 129:132-138. 

Missouri Department of Conservation. 1991. Endangered 
bats and their management in Missouri. Missouri 
Department of Conservation. Jefferson City. 8 pp. 



Gray Wolves 



by 

L. David Mech 

National Biological Service 

Daniel H. Pletscher 

University of Montana 

Clifford J. Martinka 
National Biological Service 



The gray wolf (Canis lupus) originally occu- 
pied all habitats in North America north of 
about 20° north latitude (in Mexico), except for 
the southeastern United States, where the red 
wolf (C. rufus) lived. By 1960 the wolf was 
exterminated by federal and state governments 
from all of the United States except Alaska and 
northern Minnesota. Until recently, 24 sub- 
species of the gray wolf were recognized for 
North America, including 8 in the contiguous 
48 states. After the gray wolf was listed as an 
endangered species in 1967, recovery plans 
were developed for the eastern timber wolf {C.l. 
lycaon), the northern Rocky Mountain wolf 
(C.l. irremotus), and the Mexican wolf (C.l. bai- 
leyi). The other subspecies in the contiguous 
United States were considered extinct. 

The Eastern Timber Wolf Recovery Plan 
(U.S. Fish and Wildlife Service 1992) set as cri- 
teria for recovery the following conditions: a 
viable wolf population in Minnesota consisting 
of at least 200 animals, and either a population 
of at least 100 wolves in the United States with- 
in 160 km (100 mi) of the Minnesota popula- 



tion, or a population of at least 200 wolves if 
farther than 160 km (100 mi) from the 
Minnesota population. The Northern Rocky 
Mountain Wolf Recovery Plan (U.S. Fish and 
Wildlife Service 1987) defined recovery as 
when at least 10 breeding pairs of wolves inhab- 
it each of three specified areas in the northern 
Rockies for 3 successive years. The Mexican 
Wolf Recovery Plan (U.S. Fish and Wildlife 
Service 1982) called for a self-sustaining popu- 
lation of at least 100 Mexican wolves in a 
12,800-km 2 (4,941 -mi 2 ) range. 

A recent revision of wolf subspecies in 
North America (Nowak 1994), however, 
reduced the number of subspecies originally 
occupying the contiguous 48 states from eight 
to four. It classified the wolf currently inhabit- 
ing northern Montana as being C.l. occidental- 
is, primarily a Canadian and Alaskan wolf. It 
considered C.l. nubilus to be the wolf remaining 
in most of the range of the former "northern 
Rocky Mountain wolf and the present range of 
the eastern timber wolf; this leaves the eastern 
timber wolf extinct in its former U.S. range, sur- 



Our Living Resources — Mammals 



99 



viving now only in southeastern Canada. The 
new classification may have implications for the 
recovery criteria propounded by the Eastern 
Timber Wolf and Northern Rocky Mountain 
Wolf recovery plans. The reclassification did 
not change the status of the Mexican wolf. 

This article is based on a review of the liter- 
ature and recent personal communications. 
Most of the studies cited depended primarily on 
the use of aerial radio-tracking and observation 
(Mech 1974; Mech et al. 1988). 

Population Status by Region 

Lake Superior Region 

After wolves were protected in 1974 by the 
Endangered Species Act of 1973, their numbers 
and distribution in Minnesota increased, and 
individuals began recolonizing Wisconsin 
(Mech and Nowak 1981). The population 
increased in Wisconsin and began recolonizing 
Michigan (Hammill 1993). The Minnesota pop- 
ulation increased at about 3% per year (Fuller et 
al. 1992); its distribution continues to increase 
(Paul 1 994). The best estimate of its current size 
is 1,740-2,030 wolves. Wisconsin and mainland 
Michigan each supported an estimated 50+ 
wolves in early 1994 (A.R Wydeven, Wisconsin 
Department of Natural Resources, personal 
communication; J. Hammill, Michigan 
Department of Natural Resources, personal 
communication), and Isle Royale National Park 
about 14 wolves (Peterson 1994). 

As wolves increased in Minnesota, they also 
began dispersing westward into North and South 
Dakota (Licht and Fritts 1994). The only records 
from these states involve 10 wolves killed from 
1981 through 1992, but the possibility remains 
that small populations may occur in some of the 
more remote areas. Sufficient prey certainly exist 
there, so if dispersing wolves from Minnesota 
and Manitoba are not killed by humans, they 
should be able to breed and start populations. 

Western United States 

Wolves were virtually absent in the western 
United States (other than an occasional animal 
that disperses from Canada) from the mid- 
1930's through 1980 (Ream and Mattson 1982). 
The nearest breeding population through this 
period was probably in Banff National Park, 
Alberta. Wolves were completely protected in 
extreme southeastern British Columbia in the 
1960's (Pletscher et al. 1991). This led to recol- 
onization of the area and adjacent northwestern 
Montana, and in 1986 a den was documented in 
Glacier National Park, Montana (Ream et al. 
1989). This population, which straddles the 
Canadian border, has since grown to four packs 
and about 45 wolves. 

Three breeding packs have been reported 




elsewhere in western Montana (Fritts et al. 
1994), all probably founded by animals that dis- 
persed from Glacier National Park. 
Additionally, an animal that dispersed from 
Glacier is in northeastern Idaho, and a wolf shot 
in 1992 just south of Yellowstone National Park 
was genetically related to Glacier wolves (Fritts 
et al. 1994). Animals that have dispersed, pri- 
marily from the Glacier area, have begun back- 
filling the area between Glacier National Park 
and Jasper National Park, Alberta (Boyd et al. 
1994). This connection to larger wolf popula- 
tions in Canada will enhance the viability of the 
U.S. population. 

Although occasional wolves have been 
sighted in Wyoming and Washington and 
numerous sightings have been reported from 
central Idaho, no reproduction has been docu- 
mented in these states, with the possible excep- 
tion of litters in Washington in 1990 (S.H. 
Fritts, U.S. Fish and Wildlife Service, personal 
communication). An environmental impact 
statement on the reintroduction of wolves to 
Yellowstone and central Idaho was completed 
in early 1994. 

Factors Impeding Wolf Recovery 

In small populations, the death of any indi- 
vidual can seriously impede recovery, meaning 
that factors that may not affect larger popula- 
tions may hinder recovery of smaller ones. Such 
factors hindering the recovery of wolves include 
illegal and accidental killing of wolves by 
humans, canine parvovirus (Mech and Goyal 
1993; Johnson et al. 1994; Wydeven et al. 
1994), sarcoptic mange (A. P. Wydeven et al., 
Wisconsin Department of Natural Resources, 
personal communication), possibly Lyme dis- 
ease (Thieking et al. 1992), and heartworm 
(Dirofilario immitis; Mech and Fritts 1987). Of 
these, only killing by humans is subject to 
human control. 



Gray wo\{ (Canis lupus). 



100 



Mammals — Our Living Resources 



For further information: 

L. David Mech 

National Biological Service 

North Central Forest Experiment 

Station 

1992FolwellAve. 

St. Paul, MN 55108 



Future Outlook 

All wolf populations in the contiguous 48 
states are increasing. Minnesota wolves occupy 
all suitable areas there and even have been col- 
onizing agricultural regions where the Eastern 
Timber Wolf Recovery Team felt they should 
not be (U.S. Fish and Wildlife Service 1992). 
Thus, in 1993, the Department of Agriculture's 
Animal Damage Control Program destroyed a 
record 139 wolves for livestock depredation 
control (Paul 1994). As wolf populations con- 
tinue to grow in other newly colonized areas, 
there may be an increasing need for control of 
those wolves preying on livestock (Fritts 1993). 
Because the public has so strongly supported 
wolf recovery and reintroduction, it may be dif- 
ficult for many to understand the need for con- 
trol. Thus, strong efforts at public education 
will be required. 

References 

Boyd, D.K.. P.C. Paquet. S. Donelon, R.R. Ream. D.H. 
Pletscher. and C.C. White. 1994. Dispersal characteristics 
of a recolonizing wolf population in the Rocky Mountains. 
In L.D. Carbyn, S.H. Fritts, and D.R. Seip. eds. Ecology 
and conservation of wolves in a changing world. Canadian 
Circumpolar Institute, Edmonton, Alberta. In press. 

Fritts, S.H. 1993. The downside of wolf recovery. 
International Wolf 3(1): 24-26. 

Fritts, S.H., E.E. Bangs, J. A. Fontaine, W.G. Brewster, and 
J.F. Gore. 1994. Restoring wolves to the northern Rocky 
Mountains of the United States. In L.D. Carbyn, S.H. 
Fritts, and D.R. Seip, eds. Ecology and conservation of 
wolves in a changing world. Canadian Circumpolar 
Institute. Edmonton, Alberta. In press. 

Fuller, T.K., W.E. Berg, G.L. Radde, M.S. Lenarz. and G.B. 
Joselyn. 1992. A history and current estimate of wolf dis- 
tribution and numbers in Minnesota. Wildlife Society Bull. 
20:42-55. 

Hammill, J. 1993. Wolves in Michigan: a historical perspec- 
tive. International Wolf 3:22-23. 

Johnson, M.R.. D.K. Boyd, and D.H. Pletscher. 1994. 
Serology of canine parvovirus and canine distemper in 
relation to wolf (Cams lupus) pup mortalities. Journal of 
Wildlife Diseases 30:270-273. 

Licht, D.S., and S.H. Fritts. 1994. Gray wolf (Canis lupus) 
occurrences in the Dakotas. American Midland Naturalist 
132:74-81. 



Mech. L.D. 1974. Current techniques in the study of elusive 
wilderness carnivores. Pages 315-322 in Proceedings of 
the 11th International Congress of Game Biologists. 
National Swedish Environment Protection Board. 
Stockholm. 

Mech, L.D., and S.H. Fritts. 1987. Parvovirus and heartworm 
found in Minnesota wolves. Endangered Species Tech. 
Bull. 12(5-6): 5-6. 

Mech, L.D., S.H. Fritts, G. Radde, and W.J. Paul. 1988. Wolf 
distribution in Minnesota relative to road density. Wildlife 
Society Bull. 16:85-88. 

Mech, L.D., and S.M. Goyal. 1993. Canine parvovirus effect 
on wolf population change and pup survival. Journal of 
Wildlife Diseases 29:330-333. 

Mech, L.D., and R.M. Nowak. 1981. Return of the gray wolf 
to Wisconsin. American Midland Naturalist 105:408-409. 

Nowak. R.M. 1994. Another look at wolf taxonomy. In L.D. 
Carbyn. S.H. Fritts. and DR. Seip. eds. Ecology and con- 
servation of wolves in a changing world. Canadian 
Circumpolar Institute, Edmonton. Alberta. In press. 

Paul, W.J. 1994. Wolf depredation on livestock in Minnesota: 
annual update of statistics 1993. U.S. Department of 
Agriculture, Animal Damage Control, Grand Rapids, MN. 
10 pp. 

Peterson. R.O. 1994. Out of the doldrums for Isle Roy ale 
wolves? International Wolf 4(2): 19. 

Pletscher, D.H., R.R. Ream, R. Demarchi. W.G. Brewster, and 
E.E. Bangs. 1991. Managing wolf and ungulate popula- 
tions in an international ecosystem. Transactions of the 
North American Wildlife and Natural Resources 
Conference 56:539-549. 

Ream, R.R.. M.W. Fairchild. D.K. Boyd, and A.J. Blakesley. 
1989. First wolf den in western U.S. in recent history. 
Northwestern Naturalist 70:39-40. 

Ream, R.R.. and U.I. Mattson. 1982. Wolf status in the north- 
em Rockies. Pages 362-381 in F.H. Harrington and P.C. 
Paquet. eds. Wolves of the world. Noyes Publishing. Park 
Ridge, NJ. 

Thieking, A., S.M. Goyal. R.F. Berg. K.L. Loken. L.D. Mech. 
and R.P Thiel. 1992. Seroprevalence of Lyme disease in 
Minnesota and Wisconsin wolves. Journal of Wildlife 
Diseases 28:177-182. 

U.S. Fish and Wildlife Service. 1982. Mexican wolf recovery 
plan. USFWS, Albuquerque, NM. 103 pp. 

U.S. Fish and Wildlife Service. 1987. Northern Rocky 
Mountain wolf recovery plan. USFWS, Denver, CO. 119 
pp. 

U.S. Fish and Wildlife Service. 1992. Recovery plan for the 
eastern timber wolf. USFWS. Twin Cities. MN. 73 pp. 

Wydeven, A.P.. R.N. Schultz. and R.P. Thiel. 1994. Gray wolf 
monitoring in Wisconsin — 1979-1991. In L.D. Carbyn. 
S.H. Fritts. and D.R. Seip. eds. Ecology and conservation 
of wolves in a changing world. Canadian Circumpolar 
Institute. Edmonton. Alberta. In press. 



Black Bears in 

North 

America 

by 

Michael R. Vaughan 

National Biological Service 

Michael R. Pelton 

University of Tennessee 



Habitat loss, habitat fragmentation, and 
unrestricted harvest have significantly 
changed the distribution and abundance of 
black bears (Ursus americanus) in North 
America since colonial settlement. Although 
bears have been more carefully managed in the 
last 50 years and harvest levels are limited, 
threats from habitat alteration and fragmenta- 
tion still exist and are particularly acute in the 
southeastern United States. In addition, the 
increased efficiency in hunting techniques and 
the illegal trade in bear parts, especially gall 
bladders, have raised concerns about the effect 



of poaching on some bear populations. Because 
bears have low reproductive rates, their popula- 
tions recover more slowly from losses than do 
those of most other North American mammals. 
Black bear populations are difficult to inven- 
tory and monitor because the animals occur in 
relatively low densities and are secretive by 
nature. Black bears are an important game 
species in many states and Canada and are an 
important component of their ecosystems. It is 
important that they be continuously and careful- 
ly monitored to ensure their continued exis- 
tence. 



Our Living Resources — Mammals 



101 



Black Bear Survey Data 

Information on the distribution and status of 
black bears in North America came from sever- 
al unpublished reports and scientific publica- 
tions. Traffic USA (McCracken et al. 1995) 
reports periodically on the status of black bears 
in North America. Two reports on the status and 
conservation of the bears of the world were pre- 
sented at meetings of the International 
Conference on Bear Research and Management 
in 1970 and 1989 (Cowan 1972; Servheen 
1990). Finally, much of the information for this 
report is from data collected by survey for a 
report by the International Union for the 
Conservation of Nature and Natural 
Resources/Species Survival Commission 
(IUCN/SSC) Bear Specialist Group (Pelton et 
al. 1994). 

Range and Status 

Black bears historically ranged over most of 
the forested regions of North America, includ- 
ing all Canadian provinces, Alaska, all states in 
the conterminous United States, and significant 
portions of northern Mexico (Hall 1981; Fig. 1). 
Their current distribution is restricted to rela- 
tively undisturbed forested regions (Pelton 
1982; Pelton et al. 1994; Fig. 2). Black bears 
can still be found throughout Canada with the 
exception of Prince Edward Island (extirpated 
in 1937), and in at least 40 of the 50 states; their 
status in Mexico is uncertain (Leopold 1959; 
Fig. 2). 

In the eastern United States black bear range 
is continuous throughout New England but 
becomes increasingly fragmented from the mid- 
Atlantic down through the Southeast (Maehr 





1984). In the Southeast, most populations are 
now restricted to the Appalachian mountain 
chain or to coastal areas intermittently in all 
states from Virginia to Louisiana (J. Wooding, 
Florida Freshwater Fish and Game 
Commission, unpublished data). 

Recently, 1 1 Canadian provinces and territo- 
ries reported stable black bear populations, and 
10 provinces and territories estimated popula- 
tion sizes totaling about 359,000-373,000 
(Pelton et al. 1994; McCracken et al. 1995; 
Table 1). Bears are legally harvested in all 
Canadian provinces and territories; total annual 
mortality from all sources (e.g., hunting, road 
kills, nuisance kills) is estimated at more than 
23,000 (Pelton et al. 1994). 



Province 


Population estimate 


Trend 


Alberta 


39,600 


Stable 


British Columbia 


121,600 


Stable 


Manitoba 


25,000 


Stable 


New Brunswick 


Unknown 


Stable/declining* 


Newfoundland 


6,000-10,000 


Stable 


Northwest Territories 


5,000+" 


Stable 


Nova Scotia 


3,000 


Stable 


Ontario 


65,000-75,000 


Stable/increasing 


Quebec 


60,000 


Stable 


Saskatchewan 


24,000" 


Stable 


Yukon 


10,000 


Stable 


Total 


359,200-373,200 





Fig. 1. Historical distribution of the American black bear 
(modified from Hall 1981). 



' Stable — East and Northeast; declining — West and Central. 
"1991 or 1992 estimates from McCracken et al. (1995). 

Thirty-eight of 40 states responding to a 
1993 survey (Pelton et al. 1994) reported stable 
or increasing populations; only Idaho and New 
Mexico reported decreasing populations (Table 
2). Based on data from 38 states, the total pop- 
ulation estimate for black bears in the United 
States ranges from about 307,000 to 332,000 
(excluding South Dakota and Wyoming). Black 
bears are listed as threatened or endangered in 
Florida, Louisiana, Mississippi, South Dakota, 



Fig. 2. Present distribution of the 
American black bear, based on 
survey responses from provinces 
and states (Pelton 1994) and 
research projects in Mexico (D. 
Doan, Texas A & I University, per- 
sonal communication). 



Table 1. Population estimates and 
trends of American black bears in 
Canada (adapted from Pelton et al. 
1994). 



102 



Mammals — Our Living Resources 



Table 2. Population estimates and 
trends of American black bears in 
the United States (adapted from 
Pelton et al. 1994). 



and Texas; rare in Missouri; and protected in 
Kentucky. They are unclassified in Connecticut. 
The remainder of the 40 states responding to the 
survey classify black bears as a game species 
(Table 2). In 1970 Arizona and Nevada listed 
black bears as a protected species and Texas 
listed them as game (Cowan 1972); thus the cur- 
rent classifications (Table 2) represent an 
upgrade in status for Arizona and Nevada and a 
downgrade for Texas. The status of bears in all 
remaining states covered in both surveys 
remained essentially unchanged. 

The Southern Appalachian Region 
(Tennessee, North Carolina, South Carolina, 
and Georgia) is an area of special concern, and 
bear populations there have been routinely 
monitored since the late 1960's by the Southern 
Appalachian Bear Study Group. Initial esti- 
mates placed the population at 2,000-2,500 
bears. The establishment of a network of black 
bear sanctuaries in the 1970's, scattered 
throughout the national forests in North 
Carolina, Tennessee, and Great Smoky 
Mountains National Park, provided protection 



State 


Estimated 
population size 


Population trend 


Status 


Alabama 


<50 


Stable 


Game 


Alaska 


100,000* 


Stable 


Game 


Arizona 


2,500 


Stable 


Game 


Arkansas 


2,200 


Slightly increasing 


Game 


California 


20,000 


Slightly increasing 


Game 


Colorado 


8,000-12,000 


Unknown 


Game 


Connecticut 


15-30 


Increasing 


Unclassified 


Florida 


1,000-2,000 


Stable 


Threatened 


Georgia 


1,700 


Slightly increasing 


Game 


Idaho 


20,000-25,000* 


Slightly decreasing 


Game 


Kentucky 


<200 


Increasing 


Protected 


Louisiana 


200-400 


Slightly increasing 


Threatened 


Maine 


19,500-20,500 


Stable 


Game 


Maryland 


175-200 


Slightly increasing 


Game 


Massachusetts 


700-750 


Slightly increasing 


Game 


Michigan 


7,000-10,000 


Slightly increasing 


Game 


Minnesota 


15,000 


Increasing 


Game 


Mississippi 


<50 


Slightly increasing 


Endangered 


Missouri 


50-130 


Increasing 


Rare 


Montana 


15,000-20,000 


Stable 


Game 


Nevada 


300 


Increasing 


Game 


New Hampshire 


3,500 


Increasing 


Game 


New Jersey 


275-325 


Increasing 


Game 


New Mexico 


3,000 


Decreasing 


Game 


New York 


4,000-5,000 


Slightly increasing 


Game 


North Carolina 


6,100 


Increasing 


Game 


Oklahoma 


120 


Increasing 


Game 


Oregon 


25,000 


Increasing 


Game 


Pennsylvania 


7,500 


Stable 


Game 


South Carolina 


200 


Slightly increasing 


Game 


South Dakota 


Unknown 


Unknown 


Threatened 


Tennessee 


750-1,500 


Increasing 


Game 


Texas 


50* 


Increasing 


Threatened 


Utah 


800-1,000 


Slightly increasing 


Game 


Vermont 


2,300 


Stable 


Game 


Virginia 


3,000-3,500 


Slightly increasing 


Game 


Washington 


27,000-30,000 


Increasing 


Game 


West Virginia 


3,500 


Increasing 


Game 


Wisconsin 


6,200 


Slightly increasing 


Game 


Wyoming 


Unknown 


Stable 


Game 


Total 


306,935-331,805 








'1991 estimates from McCracken et al. (1995). 



Black bear (Ursus americanus). 

for bears in the region, and estimates remain at 
2.000-2,500 bears. 

Two of 16 recognized subspecies of black 
bears (Hall 1981) require special mention: the 
Louisiana bear (U.a. luteolus), with a range of 
east Texas, all of Louisiana, and southern 
Mississippi; and the Florida bear (U.a. flori- 
danus), with a range of Florida and southern 
Alabama. The U.S. Fish and Wildlife Service 
was petitioned in 1987 and 1990 to list the 
Louisiana bear and the Florida bear, respective- 
ly, as endangered species under the Endangered 
Species Act of 1973. In 1992 the Louisiana bear 
was officially placed on the federal endangered 
species list as a threatened species, and the 
Florida bear was placed in a "warranted but pre- 
cluded" category. This latter category indicates 
that although biological evidence supports list- 
ing, several other species of higher priority are 
awaiting listing and will be listed before the 
Florida bear. At present, the U.S. Fish and 
Wildlife Service is considering listing bears in 
southern but not northern Florida. 

Given the data available, the total minimum 
population of black bears reported in North 
America approaches 650,000-700.000. Total 
annual mortality (mostly from hunting) for the 
United States (more than 19,000) and Canada 
(more than 23,000) exceeds 42.000. which is 
less than 10% of the known population. Many 
state wildlife agencies accept that bear popula- 
tions can sustain 20%-25% annual harvest mor- 
tality, with the understanding that some areas 
are more sensitive to overharvest than others. 
Thus, except for those in the southeastern 
United States and in Idaho and New Mexico, 
North American black bear populations appear 
stable or on the increase. Only concentrated 
research on isolated populations of bears 
remaining in the southeastern United States will 
answer questions concerning the long-term via- 
bility of those populations. 



Our Living Resources — Mammals 



103 



References 

Cowan, I.M. 1972. The status and conservation of bears 

(Ursidae) of the world — 1970. International Conference 

on Bear Research and Management 2:343-367. 
Hall, E.R. 1981. The mammals of North America. 2nd ed. 

John Wiley and Sons, New York. 1,181 pp. 
Leopold. A.S. 1959. Wildlife of Mexico. University of 

California Press, Berkeley. 608 pp. 
Maehr. D.S. 1984. Distribution of black bears in eastern 

North America. Eastern Workshop on Black Bear 

Research and Management 7:74. 
McCracken, C, K.A. Johnson, and D. Rose. 1995. Status, 

management, and commercialization of the American 



black bear (Ursus americanus). Traffic USA. 

Washington, DC. In press. 
Pelton, M.R. 1982. Black bear. Pages 504-514 in J. A. 

Chapman and G.A. Feldhamer, eds. Wild mammals of 

North America; biology, management, and economics. 

John Hopkins University Press, Baltimore and London. 
Pelton, M.R., F. vanManen. A. Coley, K. Weaver, J. 

Pedersen, and T. Eason. 1994. Black bear conservation 

action plan — North America. IUCN/SSC Bear Specialist 

Group Tech. Rep. In press. 
Servheen, C. 1990. The status and conservation of the bears 

of the world. International Conference on Bear Research 

and Management. Monograph Series 2. 32 pp. 



For further information: 

Michael R. Vaughan 

National Biological Service 

Virginia Cooperative Fish and 

Wildlife Research Unit 

Virginia Polytechnic Institute and 

State University 

Blacksburg. VA 24061 



Grizzly bears (Ursus arctos) once roamed 
over most of the western United States from 
the high plains to the Pacific coast (Fig. 1 ). In the 
Great Plains, they seem to have favored areas 
near rivers and streams, where conflict with 
humans was also likely. These grassland griz- 
zlies also probably spent considerable time 
searching out and consuming bison that died 
from drowning, birthing, or winter starvation, 
and so were undoubtedly affected by the elimi- 
nation of bison from most of the Great Plains in 
the late 1800's. They are potential competitors 
for most foods valued by humans, including 
domesticated livestock and agricultural crops, 
and under certain limited conditions are also a 
potential threat to human safety. For these and 
other reasons, grizzly bears in the United States 
were vigorously sought out and killed by 
European settlers in the 1800's and early 1900's. 

Between 1850 and 1920 grizzlies were elim- 
inated from 95% of their original range, with 
extirpation occurring earliest on the Great Plains 
and later in remote mountainous areas (Fig. la). 
Unregulated killing of grizzlies continued in 
most places through the 1950's and resulted in a 
further 52% decline in their range between 1920 
and 1970 (Fig. lb). Grizzlies survived this last 
period of slaughter only in remote wilderness 
areas larger than 26,000 km 2 (10,000 mi 2 ). 
Altogether, grizzly bears were eliminated from 
98% of their original range in the contiguous 
United States during a 100-year period. 

Because of this dramatic decline and the 
uncertain status of grizzlies in areas where they 
had survived, their populations in the contiguous 
United States were listed as threatened under the 
Endangered Species Act in 1975. High levels of 
grizzly bear mortality in the Yellowstone area 
during the early 1970's were also a major impe- 
tus for this listing. Grizzly bears persist as iden- 
tifiable populations in five areas (Fig. lb): the 
Northern Continental Divide, Greater 
Yellowstone, Cabinet- Yaak, Selkirk, and North 
Cascade ecosystems. All these populations 
except Yellowstone's have some connection with 
grizzlies in southern Canada, although the cur- 
rent status and future prospects of Canadian 
bears are subject to debate. The U.S. portions of 



these five populations exist in designated recov- 
ery areas, where they receive full protection of 
the Endangered Specie^ Act. 

Grizzlies potentially occur in two other areas: 
the San Juan Mountains of southern Colorado 
and the Bitterroot ecosystem of Idaho and 
Montana. There are no plans for augmenting or 
recovering grizzlies in the San Juan Mountains, 
and serious consideration is being given to rein- 
troducing grizzlies into the Bitterroots as an 
"experimental nonessential" population. 




Grizzly Bears 



by 

David J. Mattson 

R. Gerald Wright 

Katherine C. Kendall 

Clifford J. Martinka 

National Biological Service 



Distribution in 1850 
■ Distribution in 1970-90 
□ Occasional sightings or 

potential occurrences 



Fig. 1. Approximate distribution 
of grizzly bears in 1 850 compared 
to 1920 (a; Merriam 1922) and 
1970-90 (b). Local extinction 
dates, by state, appear in (a). 
Populations identified in (b) are 
NCE — North Cascades ecosys- 
tem, SE — Selkirk ecosystem. 
CYE — Cabinet- Yaak ecosystem, 
BE — Bitterroot ecosystem, 
NCDE — Northern Continental 
Divide ecosystem, GYE — 
Greater Yellowstone ecosystem. As 
indicated in (b), a grizzly was 
killed in the San Juan Mountains 
of southern Colorado in 1979. 



104 



Mammals — Our Living Resources 



Table. Recent population and 
trend estimates for areas in the 
contiguous United States occupied 
or potentially occupied by grizzly 
bears (NCDE — Northern 
Continental Divide ecosystem, 
GYE — Greater Yellowstone 
ecosystem, CYE — Cabinet- Yaak 
ecosystem, C — Cabinet portion 
only (95% confidence interval), 
SE — Selkirk ecosystem, NCE — 
North Cascades ecosystem, BE — 
Bitterroot ecosystem, SJE — San 
Juan ecosystem). 



Status and Trends 

Recent research in the Northern Continental 
Divide, Yellowstone, and Selkirk ecosystems 
has produced growth and size estimates for 
these grizzly bear populations. Study results, 
however, have been compromised by either 
small sample sizes, incomplete coverage, or 
possibly unrepresentative samples. These types 
of studies are also relatively expensive and 
require the capture and radio tagging of bears, 
although without the aid of radio tagging, it is 
even more difficult to directly count or other- 
wise monitor grizzly bear populations in their 
extensive, typically forested, ranges. 

Because of these difficulties, we have only 
rough estimates of size for U.S. grizzly bear 
populations. Many grizzlies exist only in the 
Northern Continental Divide and Yellowstone 
ecosystems. We can be confident that there are 
at least 175 bears in the Northern Continental 
Divide ecosystem and 142 in the Yellowstone 
ecosystem, and a minimum of about 360 in the 
entire contiguous United States (Table). On the 
other hand, it is unlikely that more than 75 ani- 
mals inhabit each of the Cabinet-Yaak, Selkirk, 
and North Cascade populations. 

We have few reliable estimates of population 
trends for the same reasons that we have few 
reliable estimates of population size. In most 
cases we do not have any information on trends 
or the populations are so small (as in the 
Selkirks) that the death of only a few individu- 
als can turn a growing population into a declin- 
ing one (Table). Current best estimates for the 
Northern Continental Divide and Yellowstone 



Minimum 
population estimate 



Population estimate 
assuming 60% sightabi!ity a 



Area Average (mean) Range (95% CI) Average (mean) Range (95% CI) Trend estimate b Long-term viability 



NCDE C 


242 d 


175-308 


404 


293-514 


Stable to slightly + e 


? 


NCDE f 


302 d 


219-384 


502 


365-640 






GYE9 


197 d 


142-252 


329 


237-420 


ca. +0.01 h 


? 


CYE 1 


<15 




29 


9-551 


? 


Not viable 


SE k 


26-36 ' 




9 




to +0.02 k , recently-" 1 


Not viable 


NCE n 


10-20' 




<50' 




? 


Not viable 


BE 







Possible presence 




? 


Not viable 


SJE 







Possible presence 




? 


Not viable 



a Based on results trom Aune and Kasworm (1989) suggesting that 60% of adult females were observed in their study 
area. Accordingly, minimum population estimates are divided by 0.6. 

Expressed as an increasing (+) or decreasing (-) population, where available in terms of per capita rate of increase or 
decrease per year. A "?" indicates populations for which there are no substantive or reliable estimates of trend. 
c Data from USFWS (1993) and MFWP (1993). 

d Mean and 95% confidence intervals for 3-year sums of "unduplicated" adult females observed in an area (n - 4 years, 
except for CYE n = 3 years) minus known adult female mortality for the corresponding 3-year period, divided by 0.284 (the 
assumed proportion of adult females in the population) for NCDE and GYE. 
e From Keating (1986), Aune and Kasworm (1989), McLellan (1989), and MFWP (1993). 

'Using 22.8% adult females in the population and assuming a 1:1 adult sex ratio, based on the upper 95% confidence inter- 
val for estimates of percentage of adults in grizzly bear populations from the NCDE (MFWP 1993). 
9Data from Knight etal. (1993). 
h From Knight etal. (1988). 

'Data for 1986-90 from MFWP (1993). Minimum population estimate is for the Cabinet portion only. Data from USFWS 
(1993). 

'The lower confidence interval = 0, but 9 bears were radio-marked and known to be alive. 
k FromWielgus(1993). 
'including bears in adjacent Canada. 

m From R.B. Wielgus, University of British Columbia, Vancouver, personal communication (1994). 
"From Almack et al. (1991). 



areas suggest that these largest populations have 
been stable or slightly increasing in recent 
years. Even for these relatively well-studied 
populations, however, obtaining a reliable esti- 
mate of trends is difficult because of large and 
diverse study areas, small samples, and poten- 
tially biased observations. 

Long-term viability of a population or 
species is achieved when there are enough ani- 
mals and sufficient secure and productive habi- 
tat to ensure that the population or species will 
survive for the indefinite future. Certainly, 
direct mortality that accompanied the arrival of 
European settlers had catastropic consequences 
for grizzly bears. Other catastrophes related to 
disease, climate change, and changes in human 
values could yet be visited upon grizzlies. 

Viability analysis is not an exact science, yet 
there are some rules of thumb that can be used 
to identify populations at substantially greater 
risk of extinction than others. For example, 
among existing isolated populations of brown 
bears (also U. arctos) and grizzly bears world- 
wide, only populations that were reduced to no 
fewer than about 450 bears responded with 
rapid growth when given protection. 
Conversely, even with protection, populations 
smaller than 200 continued to decline (Mattson 
and Reid 1991). All of these smaller popula- 
tions also occupied areas less than 10,000 km 2 
(3,900 mi 2 ) at the time they were given legal 
protection. This relationship between range size 
and vulnerability is consistent with the fact that 
only North American grizzly populations occu- 
pying areas larger than 26,000 km 2 (10,500 
mi 2 ) in 1920 survived to the present. The 
Selkirk and Cabinet-Yaak ecosystems are about 
5,200 km 2 (about 2,000 mi 2 ) and the remaining 
ecosystems are about 24,600-29,500 km 2 
(about 9,500-11,400 mi 2 ). We expect popula- 
tions with current ranges less than 29,500 km 2 
(1 1,400 mi 2 ) to be at substantially greater risk 
of extinction. 

Exchange of genes among individuals and 
populations is also important to survival of pop- 
ulations. Allendorf et al. (1991) estimated that 
populations of about 500 interbreeding grizzlies 
may be required to maintain normal levels of 
genetic diversity. This genetically effective pop- 
ulation size equates to total population sizes of 
around 2,000 because not all bears breed. Given 
that the maximum documented movement of 
grizzly bears away from their mother's range is 
45-105 km (28-65 mi; Blanchard and Knight 
1991), it is unlikely that populations separated 
by a greater distance exchange breeding ani- 
mals. Furthermore, bear movement across these 
gaps is entirely dependent upon their surviving 
often hostile conditions. 

No grizzly bear population in the contiguous 
United States could be considered robust by our 



Our Living Resources — Mammals 



J 05 



rules of thumb for population viability. Clearly, 
the small populations of the North Cascade, 
Selkirk, and Bitterroot ecosystems, the San 
Juan Mountains, and the U.S. portion of the 
Cabinet-Yaak ecosystem are not viable. 
Although the North Cascade ecosystem is close 
to 26,000 km 2 (10,000 mi 2 ), its prospects are 
compromised by its isolation, even from popu- 
lations in Canada. Similarly, although the 
Cabinet-Yaak and Selkirk populations can 
potentially receive bears that have dispersed 
from other populations, their 5,200-km 2 (2,000- 
mi 2 ) ranges are within the size boundaries of 
many U.S. populations that went extinct 
between 1920 and 1970 (Fig. 2) and are similar 
to those of European populations that appear to 
be declining toward extinction. 

Prospects for the larger Northern 
Continental Divide and Greater Yellowstone 
populations are better but still uncertain. The 
Yellowstone population is probably no larger 
than 420 animals (Table) and is very isolated, 
making its long-term status tenuous. The 
Northern Continental Divide population proba- 
bly has the best prospects because it is the 
largest population, in the largest area, and with- 
in the range of movement of other grizzly bear 
populations. Nonetheless, even this population 
is near the thresholds of 450 animals and the 
26,000-km 2 (10,000-mi 2 ) range size historical- 
ly associated with persistence of grizzlies in the 
United States and Europe. 

The prognosis for the Selkirk, Cabinet-Yaak, 
and Northern Continental Divide populations 
might be improved if their connections with 
Canadian grizzly populations were considered. 
These southern Canadian grizzlies, however, do 
not have protection comparable to the U.S. 
Endangered Species Act and, outside of national 
parks, they are all hunted. There is also serious 
debate over the status of Canadian grizzly popu- 
lations, especially in southwest Alberta and the 
northern Selkirks. Thus, there is no evidence that 
Canadian grizzlies will guarantee the long-term 
survival of neighboring U.S. populations. 

Implications 

Since listing of the species under the 
Endangered Species Act in 1975, populations 
have probably stabilized in the Yellowstone and 
Northern Continental Divide ecosystems. Little if 
any of the former range has been reoccupied, 
however, and five of seven potential or existing 
populations do not have optimistic prospects, and 
even the two largest populations remain at risk. 

About 88% of all grizzly bears that have 
been studied and died within the United States 
during the last 20 years were killed by humans, 
both legally and illegally. Humans remain the 
almost exclusive source of grizzly mortality, 



despite protection under the Endangered 
Species Act. Improved protection of these pop- 
ulations is accordingly dependent upon reduc- 
ing the frequency of contact between grizzly 
bears and humans, primarily by managing lev- 
els of human activity in areas where we want 
grizzly bears to survive. 

The Selkirk and Cabinet-Yaak grizzly bear 
populations may also need to be augmented by 
management if they are to survive beyond the 
next 100 years, whereas the North Cascade, 
Bitterroot, and San Juan populations will 
require the import of bears from elsewhere if 
they are to grow or persist even in the short 
term. The Yellowstone and Northern 
Continental Divide populations will need at 
least existing levels of protection, along with 
reliable monitoring and timely management. 

References 

Allendorf, F.W.. R.B. Harris, and L.H. Metzgar. 1991. 
Estimation of effective population size of grizzly bears 
by computer simulation. Pages 650-654 in E.C. Dudley, 
ed. The unity of evolutionary biology: Proceedings of the 
Fourth International Congress of Systematic and 
Evolutionary Biology. Vol. 2. Dioscorides Press, 
Portland, OR. 

Almack, J. A., W.L. Gaines, PH. Morrison, J.R. Eby, R.H. 
Naney, G.F. Wooten, S.H. Fitkin, and E.R. Garcia. 1991. 
North Cascades grizzly bear ecosystem evaluation: final 
report. Interagency Grizzly Bear Committee, Denver, 
CO. 146 pp. 

Aune, K., and W. Kasworm. 1989. Final report: East Front 
grizzly studies. Montana Department of Fish, Wildlife, 
and Parks, Helena. 332 pp. 

Blanchard, B.M., and R.R. Knight. 1991. Movements of 
Yellowstone grizzly bears. Biological Conservation 
58:41-67. 

Keating, K.A. 1986. Historical grizzly bear trends in 
Glacier National Park, Montana. Wildlife Society Bull. 
14:83-87. 

Knight. R.. J. Beecham, B. Blanchard, L. Eberhardt, L. 
Metzgar, C. Servheen, and J. Talbott. 1988. Report of the 
Yellowstone grizzly bear population task force: equiva- 
lent population size for 45 adult females. Interagency 
Grizzly Bear Committee. Denver, CO. 8 pp. 

Knight, R.R., B.M. Blanchard, and D.J. Mattson. 1993. 
Yellowstone grizzly bear investigations: annual report of 
the Interagency Study Team 1992. National Park Service. 
Bozeman, MT 26 pp. 

Mattson, D.J.. and M.W. Reid. 1991. Conservation of the 
Yellowstone grizzly bear. Conservation Biology 5:364- 
372. 

McLellan, B.N. 1989. Dynamics of a grizzly bear popula- 
tion during a period of industrial resource extraction. 3. 
Natality and rate of increase. Canadian Journal of 
Zoology 67:1865-1868. 

Merriam, C.H. 1922. Distribution of grizzly bears in U.S. 
Outdoor Life (December):405-406. 

MFWR 1993. Five year update of the programmatic envi- 
ronmental impact statement: the grizzly bear in north- 
western Montana, 1986-1990. Montana Department of 
Fish, Wildlife, and Parks, Helena. 228 pp. 

USFWS. 1993. Grizzly bear recovery plan. U.S. Fish and 
Wildlife Service, Missoula, MT. 181 pp. 

Wielgus, R.B. 1993. Causes and consequences of sexual 
habitat segregation in grizzly bears. Ph.D. thesis. 
University of British Columbia, Vancouver. 88 pp. 



For further information: 

David J. Mattson 

National Biological Service 

Cooperative Park Studies Unit 

Department of Fish and Wildlife 

Resources 

University of Idaho 

Moscow, ID 83843 



106 



Mammals — Our Living Resources 



Black-footed 
Ferrets 

by 

Dean Biggins 

Jerry Godbey 

National Biological Service 



120 

100 

d 8 °- 

75 60 

-40- 
20 
0- 



S^ 



I I 



<1900 00-19 20-39 40-59 60-79 
Years 

Fig. 1. Black-footed ferrets col- 
lected before 1980. 



=■ 3 




83 84 85 86 87 88 89 90 91 92 
Year 

Fig. 2. Black-footed ferret popu- 
lation from Meeteetse. Wyoming. 
1983-92 (all captive from 1986 to 
present). 



The black-footed ferret (Mustela nigripes) 
was a charter member of endangered 
species lists for North America, recognized as 
rare long before the passage of the Endangered 
Species Act of 1973. This member of the weasel 
family is closely associated with prairie dogs 
(Cynomys spp.) of three species, a specializa- 
tion that contributed to its downfall. Prairie 
dogs make up 90% of the ferret diet; in addition, 
ferrets dwell in prairie dog burrows during day- 
light, venturing out mostly during darkness. 
Trappers captured black-footed ferrets during 
their quests for other species of furbearers. 
Although the species received increased atten- 
tion as it became increasingly rare, the number 
of documented ferrets fell steadily after 1940 
(Fig. 1), and little was learned about the animals 
before large habitat declines made studies of 
them difficult. These declines were brought 
about mainly by prairie dog control campaigns 
begun before 1900 and reaching high intensity 
by the 1920's and 1930's. 

Much of what is known about black-footed 
ferret biology was learned from research during 
1964-74 on a remnant population in South 
Dakota (Linder et al. 1972; Hillman and Linder 
1973), and from 1981 to the present on a popu- 
lation found at Meeteetse, Wyoming, and later 
transferred to captivity (Biggins et al. 1985; 
Forrest et al. 1988; Williams et al. 1988). Nine 
ferrets from the sparse South Dakota population 
(only 1 1 ferret litters were located during 1964- 
72) were taken into captivity from 1971 to 
1973, and captive breeding was undertaken at 
the U.S. Fish and Wildlife Service's Patuxent 
Wildlife Research Center in Maryland 
(Carpenter and Hillman 1978). Although litters 
were born there, no young were successfully 
raised. The last of the Patuxent captive ferrets 
died in 1978, and no animals were located in 
South Dakota after 1979. 

Black-footed ferrets were "rediscovered" in 
prairie dog complexes at Meeteetse in 1981, 
giving conservationists what seemed a last 
chance to learn about the species and possibly 
save it from extinction. That population 
remained healthy (70 ferret litters were counted 
from 1982 to 1986) through 1984 (Fig. 2), a 
period when much was learned about ferret life 
history and behavior. In 1985, sylvatic plague, a 
disease deadly to prairie dogs, was confirmed in 
the prairie dogs at Meeteetse, creating fear that 
the prairie dog habitat vital for ferrets would be 
lost. In addition, field biologists were reporting 
a substantial decrease in the number of ferrets 
detected. The fear of plague was quickly over- 
shadowed by the discovery of canine distemper 
in the ferrets themselves. It is a disease lethal to 
ferrets. 

In 1985 six ferrets were captured to begin cap- 




Black-footed ferrets, almost extinct by 1985. are being 
reintroduced from captive breeding but still lack genetic 
diversity. 

tive breeding, but two of them brought the dis- 
temper virus into captivity, and all six died 
(Williams et al. 1988). A plan was formulated to 
place more animals from Meeteetse into captivi- 
ty to protect them from distemper and to start the 
breeding program. By December 1985, only 10 
ferrets were known to exist, 6 in captivity and 4 
at Meeteetse. The following year, the surviving 
free-ranging ferrets at Meeteetse produced only 
two litters, a number thought too small to sustain 
the wild population. Because both the Meeteetse 
and captive populations were too small to sustain 
themselves, all remaining ferrets were removed 
from the wild, resulting in a captive population of 
18 individuals by early 1987. 

Captive breeding of ferrets eventually 
became successful (Fig. 2). Although the captive 
population is growing, researchers fear the con- 
sequences of low genetic diversity (already doc- 
umented by O'Brien et al. 1989) and of inbreed- 
ing depression (see glossary). A goal of the 
breeding program is to retain as much genetic 
diversity as possible, but the only practical way 
to increase diversity is to find more wild ferrets. 
In spite of intensive searches of the remaining 
good ferret habitat and investigations of sighting 
reports, no wild ferrets have been found. 

The captive breeding program now is pro- 
ducing sufficient surplus ferrets for reintroduc- 
tion into the wild; 187 ferrets were released into 
prairie dog colonies in Shirley Basin, Wyoming, 
during 1991-93. Challenges facing the black- 
footed ferret reintroduction include low sur- 
vivorship of released ferrets due to high disper- 
sal and losses to other predators; unknown 
influence of low genetic diversity; canine dis- 
temper hazard; indirect effect of plague on 
prairie dogs and possible direct effect on ferrets; 
and low availability of suitable habitat for rein- 
troduction. The scarcity of habitat reflects a 
much larger problem with the prairie dog 
ecosystem and needs increased attention. 

At the turn of this century, prairie dogs 
reportedly occupied more than 40 million ha 



Our Living Resources — Mammals 



107 



(100 million acres) of grasslands, but by 1960 
that area had been reduced to about 607,500 ha 
(1.5 million acres; Marsh 1984). Much reduc- 
tion was attributed to prairie dog control pro- 
grams, which continue. For example, in South 
Dakota in the late 1980's, $6.2 million was 
spent to apply toxicants to prairie dog colonies 
on Pine Ridge Indian Reservation (Sharps 
1988). At least two states (Nebraska and South 
Dakota) have laws prohibiting landowners from 
allowing prairie dogs to flourish on their prop- 
erties; if the land manager does not "control" 
the "infestation," the state can do so and bill 
expenses to the owner (Clarke 1988). 

Sylvatic plague also has been devastating to 
prairie dogs and was the likely cause of the dra- 
matic decline in prairie dogs at Meeteetse. 
Although the Meeteetse complex recently sup- 
ported the densest and most vigorous popula- 
tion of black-footed ferrets ever known, it can- 
not be considered as ferret habitat now because 
of plagued-induced losses of prairie dogs. 
Plague is present in most of the monitored 
white-tailed prairie dog (Cynomys leuciirus) 
complexes, including the Shirley Basin ferret 
reintroduction site (Table). The plague's persis- 
tence could be responsible for the generally 
lower densities of white-tailed prairie dogs 
(averaging fewer than seven prairie dogs per 
hectare or fewer than three per acre). 

Several prairie dog complexes have been eval- 
uated as sites for reintroduction of black-footed 
ferrets (Table). The evaluation involves grouping 
clusters of colonies separated by fewer than 7 km 
(4.3 mi) into complexes, based on movement 
capabilities of ferrets (Biggins et al. 1993); these 
areas include some of the best prairie dog com- 
plexes remaining in the states. Nevertheless, 
other extensive prairie dog complexes were not 
considered for ferret reintroduction. 

Most of the original range of the black-foot- 



ed ferret was associated with black-tailed prairie 
dog (Cynomys ludovicianus) complexes, which 
now exhibit the highest population densities of 
all prairie dogs (Table). Black-footed ferret rein- 
troductions recently began at black-tailed prairie 
dog complexes near Malta, Montana, and 
Badlands National Park, South Dakota (Table). 
At present, the best example of a large complex 
of black-tailed prairie dogs is near Nuevos Casas 
Grandes, Chihuahua, Mexico (Table). It supports 
an impressive associated fauna and is a potential 
reintroduction site for black-footed ferrets. 

Ramifications of a healthy prairie dog 
ecosystem extend well beyond black-footed fer- 
rets. The prairie dog is a keystone species of the 
North American prairies. It is an important pri- 
mary consumer, converting plants to animal 
biomass at a higher rate than other vertebrate 
herbivores of the short-grass prairies, and its 
burrowing provides homes for many other 
species of animals and increases nutrients in 
surface soil. This animal also provides food for 
many predators. We estimated it takes 700-800 
prairie dogs to annually support a reproducing 
pair of black-footed ferrets and a similar bio- 
mass of associated predators (Biggins et al. 
1993), suggesting that large complexes of 
prairie dog colonies are necessary to support 
self-sustaining populations of these second- 
order consumers. 

The 98% loss of the productive prairie dog 
ecosystem has not yet motivated legal protec- 
tion or plans for management. There is no fed- 
eral legislation directly promoting the welfare 
of the prairie dog ecosystem (even on public 
lands), and the only existing state legislation 
promotes poisoning. 

To develop a plan for remedial action, sever- 
al immediate research needs are apparent in the 
prairie dog ecosystem: determine the relative 
diversity and abundance of invertebrates and 



State 


Site 


Prairie dog 
species* 


Complex size 
(ha) 


Hectares of 
prairie dogs 


Prairie dogs 
estimate 


Prairie dogs/ha 
colony 


United States 


Arizona 


Aubrey Valley 


Gunnison's 


44,167 


7,390 


34,067 


4.61 


Colorado 


Little Snake 


White-tailed 


252,075 


31,624 


36,875 


1.17 




Wolf Creek 


White-tailed 


65,607 


3,174 


20,009 


6.30 




Sterling 


Black-tailed 


57,824 


2,366 


16,786 


7.10 


Montana 


Custer Creek 


Black-tailed 


38,879 


425 


16,750 


39.39 




Malta Bureau of Land Management 


Black-tailed 


583,430 


7,600 


167,299 


22.01 




Charles M. Russell Refuge 


Black-tailed 


28,508 


896 


22,371 


25.00 


North Dakota 


Roosevelt National Park 


Black-tailed 


14,126 


594 


39,270 


66.11 




Marmarth National Park 


Black-tailed 


7,257 


548 


21,208 


38.70 




Fort Yates 


Black-tailed 


6,739 


579 


20,823 


35.96 


South Dakota 


Badlands National Park 


Black-tailed 


17,016 


1,669 


74,081 


44.39 


Wyoming 


Meeteetse 


White-tailed 


53,846 


5,111 


1,299 


0.25 




Shirley Basin 


White-tailed 


48,987 


20,612 


75,155 


3.65 




Medicine Bow 


White-tailed 


74,958 


27,235 


24,492 


0.90 




Recluse 


Black-tailed 


98,802 


7,181 


59,895 


8.34 




Bolton Ranch 


White-tailed 


28,068 


4,420 


7,858 


1.78 




Kinney Rim 


White-tailed 


43,509 


7,220 


608 


0.08 


Mexico 


Chihuahua 


Nuevos Casas Grandes 


Black-tailed 


87,866 


54,541 


994,986 


18.24 




Three species of prairie dogs make 
up 90% of the black-footed ferret's 
diet; prairie dog burrows are also 
used by the ferrets during the day. 



Table. Prairie dog complexes 
evaluated for black-footed ferret 
reintroductions. (Some data from 
Black-footed Ferret Interstate 
Coordinating Committee.) 



"Gunnison's prairie dog (Cynomys gunnisom), white-tailed prairie dog (C. leucurus), and black-tailed prairie dog (C ludovicianus). 



108 



Mammals — Our Living Resources 



—i m —~ »>f ..-.»**Mh*>^ 



Prairie dog control campaigns, 
like this one in Arizona, circa 
19 13, contributed to the decline of 
the black-footed ferret. 



For further information: 

Dean E. Biggins 

National Biological Service 

Midcontinent Ecological Science 

Center 

4512 McMurry Ave. 

Fort Collins, CO 80525 



small- to medium-sized vertebrates on prairie 
dog complexes, as well as the degree of depen- 
dence on prairie dogs of selected associated 
species; examine the effect of complex size, as 
well as constituent colony sizes, numbers, and 
juxtaposition on diversity and abundance of 
associated species; investigate the recent histo- 
ry of plague on selected complexes to determine 
the relation between complex size (and mor- 
phology) and resistance to decimation by 
plague; and develop methods for reestablishing 
prairie dog colonies and reconstructing com- 
plexes in suitable areas where prairie dogs have 
been extirpated. 

The black-footed ferret cannot be reestab- 
lished on the grasslands of North America in 
viable self-sustaining populations without large 
complexes of prairie dog colonies. The impor- 
tance of this system to other species is not com- 
pletely understood, but large declines in some 
of its species should serve as a warning. The 
case of the black-footed ferret provides ample 
evidence that timely preventive action would be 
preferable to the inefficient "salvage" opera- 
tions. Furthermore, there is considerable risk of 
irreversible damage (e.g., genetic impoverish- 
ment) with such rescue efforts. 

References 

Biggins, D.E., B.J. Miller, L. Hanebury. R. OakJeaf, A. 
Farmer, R. Crete, and A. Dood. 1993. A technique for 
evaluating black-footed ferret habitat. Pages 73-88 in J.L. 
Oldemeyer, D.E. Biggins. B.J. Miller, and R. Crete, eds. 
Management of prairie dog complexes for the reintro- 
duction of the black-footed ferret. U.S. Fish and Wildlife 
Service Biological Rep. 13. 

Biggins, D.E., M.H. Schroeder. S.C. Forrest, and L. 
Richardson. 1985. Movements and habitat relationships 
of radio-tagged black-footed ferrets. Pages 1 1.1-11.17 in 
S.H. Anderson and D.B. Inkley. eds. Proceedings of the 
Black-footed Ferret Workshop. Wyoming Game and Fish 



Department, Cheyenne. 

Carpenter, J.W., and C.N. Hillman. 1978. Husbandry, repro- 
duction, and veterinary care of captive ferrets. 
Proceedings of the American Association of Zoo 
Veterinarians Workshop, Knoxville. TN. 1979:36-47. 

Clarke, D.C. 1988. Prairie dog control — a regulatory view- 
point. Pages 119-120 in D.W. Uresk and G. Schenbeck. 
eds. Eighth Great Plains Wildlife Damage Control 
Workshop Proceedings. U.S. Forest Service Gen. Tech. 
Rep. RM- 154. 

Forrest, S.C, D.E. Biggins. L. Richardson, T.W. Clark, T.M. 
Campbell III, K.A. Fagerstone, and E.T. Thome. 1988. 
Population attributes for the black-footed ferret (Mustela 
nigripes) at Meeteetse, Wyoming, 1981-1985. Journal of 
Mammalogy 69(2):261-273. 

Hillman, C.N., and R.L. Linder. 1973. The black-footed fer- 
ret. Pages 10-20 in R.L. Linder and C.N. Hillman. eds. 
Proceedings of the Black-footed Ferret and Prairie Dog 
Workshop. South Dakota State University Publications. 
Brookings. 

Linder. R.L., R.B. Dahlgren. and C.N. Hillman. 1972. 
Black-footed ferret-prairie dog interrelationships. Pages 
22-37 in Proceedings of the Symposium on Rare and 
Endangered Wildlife of the Southwestern U.S. New 
Mexico Department of Game and Fish. Santa Fe. 

Marsh, R.E. 1984. Ground squirrels, prairie dogs and mar- 
mots as pests on rangeland. Pages 195-208 in 
Proceedings of the Conference for Organization and 
Practice of Vertebrate Pest Control. ICI Plant Protection 
Division, Fernherst, England. 

O'Brien. S.J.. J.S. Martenson, M.A. Eichelberger. E.T. 
Thome, and F. Wright. 1989. Biochemical genetic vari- 
ation and molecular systematics of the black-footed fer- 
ret, Mustela nigripes. Pages 21-33 in Conservation biol- 
ogy and the black-footed ferret. Yale University Press. 
New Haven, CT. 

Sharps, J. 1988. Politics, prairie dogs, and the sportsman. 
Pages 117-118 in D.W. Uresk and G. Schenbeck. eds. 
Eighth Great Plains Wildlife Damage Control Workshop 
Proceedings. U.S. Forest Service Gen. Tech. Rep. RM- 
154. 

Williams. E.S.. E.T. Thome. M.J.G. Appel. and D.W. 
Belitsky. 1988. Canine distemper in black-footed ferrets 
{Mustela nigripes) from Wyoming. Journal of Wildlife 
Diseases 24:385-398. 



American 
Badgers in 
Illinois 



by 

Barbara Ver Steeg 

Illinois Natural History 

Survey 

Richard E. Warner 
University of Illinois 



The American badger (Taxidea taxus) is a 
medium-sized carnivore found in treeless 
areas across North America, such as the tall- 
grass prairie (Lindzey 1982). Badgers rely pri- 
marily on small burrowing mammals as a prey 
source; availability of badger prey may be 
affected by changes in land-use practices that 
alter prey habitat. In the midwestern United 
States most native prairie was plowed for agri- 
cultural use beginning in the mid-1800's 
(Burger 1978). In the past 100 years. Midwest 
agriculture has shifted from a diverse system of 
small farms with row crops, small grains, hay, 
and livestock pasture to larger agricultural oper- 
ations employing a mechanized and chemical 
approach to cropping. The result is a more uni- 
form agricultural landscape dominated by two 
primary row crops, corn and soybeans. The 
effects of such land-use alterations on badgers 



are unknown. In addition, other human activi- 
ties such as hunting and trapping have no doubt 
had an impact on native vertebrates such as the 
badger. Our ongoing study was initiated to 
determine the distribution and status of badgers 
in Illinois. 

Trends in carnivore abundance are difficult 
to evaluate because most species are secretive 
or visually cryptic. Trapping records, one of the 
earliest historical data sources for furbearers, 
are virtually nonexistent for badgers in the 
1800's (Obbard et al. 1987). In Illinois, badgers 
have been protected from harvest since 1957. 
Furthermore, population estimates derived from 
furbearer harvest data are complicated by mar- 
ket price bias (Erickson 1982). Thus, data for 
estimating long-term population trends in 
Illinois badgers are few and flawed. Our 
approach is to document and evaluate current 



Our Living Resources — Mammals 



109 



population parameters, behavior, and habitat 
use in the context of present and historical habi- 
tat quality and availability. 

Most research on badgers has been limited 
to the western United States. Although results 
have varied somewhat among these studies, 
average densities (estimated subjectively from 
mark-recapture and home range data) have 
ranged from 0.38 to 5 badgers/km 2 (0.98-12.95 
badgers/mi 2 ). We use radio telemetry to collect 
intensive data at a field site in west-central 
Illinois. Preliminary results suggest that indi- 
vidual badger home range size in Illinois is an 
order of magnitude larger than that of western 
badgers, implying that badger density in Illinois 
is much lower. The home range size estimates 
of two badgers in Minnesota were also larger 
than those reported for western states (Sargeant 
and Warner 1972; Lampe and Sovada 1981). 

More than 65% of the Illinois landscape is 
under intensive row-crop agriculture (Neely and 
Heister 1987). Although badger prey exist 
throughout Illinois, available prey in row crops 
is limited to small species such as the deer 
mouse (Peromyscus maniculatus), which occur 
in low uniform densities. Important prey species 
reported in the West, such as ground squirrels 
(Spermophilus spp.), have average densities 
similar to Illinois deer mice, but they are much 
larger animals and may be concentrated into 
easily hunted loose colonies (Messick and 
Hornocker 1981; Minta 1990). 

In Illinois, badgers appear to use most fre- 
quently cover types that are relatively undis- 
turbed by plowing, including hayfields, pas- 
tures, and linear habitats such as roadsides and 
fencelines. These habitats offer the greatest con- 
centration of small mammalian prey and the 
lowest frequency of agricultural disturbance. If 
badgers are limited by available prey, it is pos- 
sible that the current badger population density 
is lower than when native prairie and its accom- 
panying prey species' populations dominated 
the landscape. 

Although badgers are legally protected in 
Illinois, human-induced mortality such as vehi- 
cle collisions and agricultural accidents take a 
toll on populations. Large predators that might 
prey on adult badgers, such as the black bear 
(Ursus americanus), gray wolf {Canis lupus), 
and mountain lion (Felis concolor), have been 
extirpated since the 19th century (Hoffmeister 
1989). However, our study shows that predation 
by coyotes {Canis latrans) and domestic dogs 
significantly affects juvenile badgers; fewer 
than 70% of juveniles survive to dispersal, 
reducing overall recruitment. 

The badger's range may be expanding east- 
ward from its former boundaries within the 
Midwest; observations of range expansion in 
Missouri, southern Illinois, Indiana, and Ohio 




American badger {Taxidea ta.xus). 



suggest that agricultural practices have converted 
previously forested acres to more suitable badger 
habitat (Moseley 1934; Leedy 1947; Mumford 
1969; Hubert 1980; Mumford and Whitaker 
1982; Long and Killingley 1983; Gremillion- 
Smith 1985; Whitaker and Gammon 1988). 

Our study revealed that badgers are distrib- 
uted and breeding throughout Illinois. The 
dynamics of badger range expansion are diffi- 
cult to pinpoint, in part because of the cryptic 
nature of the species. In Illinois and probably 
the agricultural Midwest in general, individual 
badgers move over such large areas that live 
sightings or indications of badger presence are 
few and far between. Opportunistic observa- 
tions to evaluate local badger distribution 
underestimate geographic range; thus, a focused 
regionwide attempt to evaluate badger range in 
the Midwest might demonstrate a wider distri- 
bution than expected. 

Badgers in Illinois appear to be a species with 
intermediate status: though they are neither 
abundant nor of high economic value, they are 
widely distributed and have adapted to a greatly 
altered environment. Understanding what factors 
cause a species such as the badger to become 
more or less abundant is vitally important in con- 
servation biology and wildlife management. 

References 

Burger, G.V. 1978. Agriculture and wildlife. Pages 89-107 in 
H.P. Brokaw, ed. Wildlife and America. Council on 
Environmental Quality, Washington. DC. 

Erickson, D.W. 1982. Estimating and using furbearer harvest 
information. Pages 53-66 in G.C. Sanderson, ed. Midwest 
furbearer management. Central Mountains and Plains 
Section of The Wildlife Society, Wichita, KS. 

Gremillion-Smith, C. 1985. Range extension of the badger 
(Taxidea taxus) in southern Illinois. Transactions of the 
Illinois Academy of Science 78:1 11-1 14. 

Hoffmeister. D.F. 1989. Mammals of Illinois. University of 
Illinois Press, Urbana, IL. 348 pp. 

Hubert, G.F.. Jr. 1980. Badger status evaluation. Illinois 
Department of Conservation. Job Completion Report. 
Federal Aid Project W-49-R-34, Study XII. 12 pp. 

Lampe, R.P.. and M.A. Sovada. 1981. Seasonal variation in 
home range of a female badger (Taxidea taxus). Prairie 
Naturalist 15:55-58. 

Leedy, D.L. 1947. Spermophiles and badgers move east- 
ward in Ohio. Journal of Mammalogy 28:290-292. 



110 



Mammals — Our Living Resources 



For further information: 

Barbara Ver Steeg 

Illinois Natural History Survey 

607 E. Peabody Dr. 

Champaign, IL 61820 



Lindzey. F.G. 1982. The North American badger. Pages 
653-663 in J. A. Chapman and G.A. Feldhammer, eds. 
Wild mammals of North America. Johns Hopkins 
University Press, Baltimore, MD. 

Long, C.A., and C.A. Killingley. 1983. The badgers of the 
world. Charles C. Thomas Publishers, Springfield, IL. 
404 pp. 

Messick, J. P., and M.G. Hornocker. 1981. Ecology of the 
badger in southwestern Idaho. Wildlife Monograph 76. 
53 pp. 

Minta, S.C. 1990. The badger, Taxidea taxus, (Carnivora: 
Mustelidae): spatial-temporal analysis, dimorphic terri- 
torial polygyny, population characteristics, and human 
influences on ecology. Ph.D. thesis, University of 
California, Davis. 317 pp. 

Moseley, E.L. 1934. Increase of badgers in northwestern 
Ohio. Journal of Mammalogy 15:156-158. 

Mumford, R.E. 1969. Distribution of the mammals of 
Indiana. Indiana Academy of Science Monograph 
1. 114 pp. 



Mumford. R.E.. and J.O. Whitaker. Jr. 1982. Mammals of 
Indiana. Indiana University Press, Bloomington, IN. 
537 pp. 

Neely, R.D.. and C.G. Heister, compilers. 1987. The natur- 
al resources of Illinois: introduction and guide. Illinois 
Natural History Survey Special Publ. 6. 224 pp. 

Obbard, M.E., J.G. Jones, R. Newman, A. Booth. A.J. 
Satterthwaite, and G. Linscombe. 1987. Furbearer har- 
vests in North America. Pages 1007-1038 in M. Novak. 
J. A. Baker, M.E. Obbard, and B. Malloch, eds. Wild 
furbearer management and conservation in North 
America. The Ontario Trappers Association and the 
Ministry of Natural Resources, Toronto, Ontario. 

Sargeant, A.B., and D.W. Warner. 1972. Movements and 
denning habits of a badger. Journal of Mammalogy 
53:207-210. 

Whitaker, J.O., Jr., and J.R. Gammon. 1988. Endangered 
and threatened vertebrate animals of Indiana: their distri- 
bution and abundance. Indiana Academy of Science 
Monograph 5. 122 pp. 



California Sea 
Otters 



by 

James A. Estes 

Ronald J. Jameson 

James L. Bodkin 

David R. Carlson 

National Biological Service 



Information on the size, distribution, and pro- 
ductivity of the California sea otter population 
is broadly relevant to two federally mandated 
goals: removing the population's listing as 
threatened under the Endangered Species Act 
(ESA) and obtaining an "optimal sustainable 
population" under the Marine Mammal 
Protection Act. Except for the population in cen- 
tral California, sea otters (Enhydra lutris) were 
hunted to extinction between Prince William 
Sound, Alaska, and Baja California (Kenyon 
1969). Wilson et al. (1991), based on variations 
in cranial morphology, recently assigned sub- 
specific status (E. I. nereis) to the California sea 
otter. Furthermore, mitochondrial DNA analysis 
has revealed genetic differences among popula- 
tions in California, Alaska, and Asia (NBS, 
unpublished data). 

In 1977, the California sea otter was listed as 
threatened under the ESA, largely because of its 
small population size and perceived risks from 
such factors as human disturbance, competition 




Sea otter (Enhydra lutris). 



with fisheries, and pollution. Because of unique 
threats and growth characteristics, the California 
population is treated separately from sea otter 
populations elsewhere in the North Pacific. 

Survey Design 

Data on the size and distribution of the 
California sea otter population have been gath- 
ered for more than 50 years. In 1982 we devel- 
oped a survey technique in which individuals in 
most of the California sea otter's range are 
counted from shore by groups of two observers 
using binoculars and spotting scopes. 
Supplemental data for each sighting include 
group size, activity, number and size of pups, 
and habitat. Areas that cannot be counted from 
shore are surveyed from a low-flying aircraft. 
Rangewide surveys are done in late spring and 
mid-autumn. 

Population Trends, 1914-93 

The California sea otter population has 
increased steadily through most of the 1900's 
(Fig. 1). Rate of increase was about 5% per year 
until the mid-1970's. Although only one survey 
was completed between 1976 and 1982, the col- 
lective data suggest that population growth had 
ceased by the mid-1970's, and that the population 
may have declined by as much as 30% between 
the mid-1970's and early 1980's. Counts made 
since 1983 have increased at about 5%-6% per 
year. In spring 1993, 2,239 California sea otters 
were counted. 

The California sea otter's lineal range (dis- 
tance along the 9-m [5-fathom] isobath between 
the northernmost and southernmost sightings) 
has also increased, although more slowly and 
erratically than the population size (data sum- 
marized by Riedman and Estes 1990). The 



Our Living Resources — Mammals 



111 




T 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 — 

14 24 34 44 54 64 74 84 94 

Year 

Fig. 1. Trends in abundance of the California sea otter 
population, 1914-93. 

direction of range expansion was predominate- 
ly southward before 1981, but northward there- 
after. Comparison between spring surveys con- 
ducted in 1983 and 1993 (Fig. 2) is sufficient to 
draw several conclusions. First, the population's 
range limits changed little during this 10-year 
period, even though large numbers of individu- 
als accumulated near the range peripheries. 
Second, population density increased through- 
out this time, although rates of increase were 
lowest near the center of the range. Finally, the 
relative abundance of individuals has remained 
largely unchanged (compare Fig. 2a [1983 J 
with Fig. 2b [1993], noting the similarity in 
forms of distributions for kilometer segments 
10-21). 

Although the number of dependent pups 
counted in spring surveys almost doubled 
between 1983 and 1993, the geographic range 
within which these pups were born has changed 
very little (Fig. 2). Rate of annual pup produc- 
tion ranged from 0. 14 to 0.28, but in most years 
it varied between 0.18 and 0.21. There are no 
obvious trends in rate of annual pup production 
between 1983 and 1993. Although the incre- 
mental change in the population from one year 
to the next appeared positively related to the 
annual number of births, this relationship can- 
not be shown to be statistically significant. 

Implications 

From the mid-1970's to the early 1980's, the 
California sea otter population ceased growing 
and probably declined. Entanglement mortality 
in a coastal set-net fishery was the likely cause 
of this decline (Wendell et al. 1985). 
Restrictions were imposed on the fishery in 
1982, and the population apparently responded 
by resuming its prior rate of increase. 

The maximum rate of increase for sea otter 
populations is about 20% per year. Except for 
the California otters, all increasing populations 
for which data are available have grown at about 



this rate (Estes 1990). These patterns, coupled 
with the absence of any size- or density-related 
reduction in growth rates, make the relatively 
slow rate of increase in the California popula- 
tion perplexing. 

Although the ultimate reason for disparate 
growth rates among sea otter populations is 
unknown, we believe that causes relate more to 
increased mortality than diminished reproduc- 
tion. While it is difficult to compare popula- 
tion-level reproductive rates between sea otters 
in Alaska and California, longitudinal studies of 



150 



125 



100 



° 75 



Spring 1983 census 



25 



200 



175 



150 



125 



^100 



75 



50 



25 



a. 




















i, J 1 1 

i iiiiiiiiii i, 


1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 

Independents 
Spring 1993 census ■ p ups 


b. 




























ill. 




ll II 


Ill Nil 


I II I ill L, 



5 7 9 11 13 15 17 19 21 23 25 27 29 
20-km segment, north (1) to south (29) 



Fig. 2. Distribution and abun- 
dance of California sea otters in 
1983 (a) and 1993 (b). Data are 
from the spring surveys. 



112 



Mammals — Our Living Resources 



For further information: 

J. A. Estes 

National Biological Service 

University of California 

Santa Cruz, CA 95064 



marked individuals in the two regions indicate 
that both age of first reproduction and annual 
birth rate of adult females are similar. 
Furthermore, the close similarity between the 
theoretical maximum rate of increase and 
observed rates of population increase for sea 
otters in Washington, Canada, and portions of 
Alaska suggests that mortality from birth to 
senescence in these populations is quite low. In 
contrast, rates of mortality in the California sea 
otter are comparatively high, with an estimated 
40%-50% of newborns lost before weaning 
(Siniff and Ralls 1991; Jameson and Johnson 
1993; Riedman et al. 1994). This alone would 
significantly depress a population's potential 
rate of increase. Furthermore, the age composi- 
tion of beach-cast carcasses in California indi- 
cates that most postweaning deaths occur well 
in advance of physiological senescence (Pietz et 
al. 1988; Bodkin and Jameson 1991). These pat- 
terns likely explain the depressed rate of 
increase in the California sea otter population. 

Although the demographic patterns of mor- 
tality in California sea otters are becoming 
clear, the causes of deaths remain uncertain. 
There is growing evidence for the importance of 
predation by great white sharks (Carcharodon 
carcharias). Contaminants may also be having 
a detrimental effect on California sea otters, 
although as yet there is no direct evidence for 
this. However, polychlorinated biphenyl (PCB) 
and DDT levels, known to be high in the 
California Current, are also high in the liver and 
muscle tissues of California sea otters (Bacon 
1994). Of particular concern are that average 
PCB levels in California sea otters approach 
those that cause reproductive failure in mink, 
which are in the same family as otters; and 
preweaning pup losses are especially high in 
primiparous {see glossary) females. This latter 
point may be significant because environmental 



contaminants that accumulate in fat can be 
transferred via milk in extraordinarily high con- 
centrations, especially to the first-born young in 
species such as the sea otter which has pro- 
longed sexual immaturity. 

References 

Bacon, C.E. 1994. An ecotoxicological comparison of 
organic contaminants in sea otters (Enhydra lutris) 
among populations in California and Alaska. M.S. thesis. 
University of California, Santa Cruz. 55 pp. 

Bodkin, J.L., and R.J. Jameson. 1991. Patterns of seabird 
and marine mammal carcass deposition along the central 
California coast, 1980-1986. Canadian Journal of 
Zoology 69(5):1 149-1 155. 

Estes, J. A. 1990. Growth and equilibrium in sea otter popu- 
lations. Journal of Animal Ecology 59:385-401. 

Jameson, R.J., and A.M. Johnson. 1993. Reproductive char- 
acteristics of female sea otters. Marine Mammal Science 
9(2):156-167. 

Kenyon, K.W. 1969. The sea otter in the eastern Pacific 
Ocean. North American Fauna 68:1-352. 

Pietz. P., K. Ralls, and L. Ferm. 1988. Age determination of 
California sea otters from teeth. Pages 106-115 in D.B. 
Siniff and K. Ralls, eds. Population status of California 
sea otters. Final report to the Minerals Management 
Service. U.S. Department of the Interior 
14-12-001-3003. 

Riedman. M.L., and J. A. Estes. 1990. The sea otter 
(Enhydra lutris): behavior, ecology, and natural history. 
U.S. Fish and Wildlife Service Biological Rep. 90(14). 
126 pp. 

Riedman M.L.. J. A. Estes, M.M. Staedler, A. A. Giles, and 
D.R. Carlson. 1994. Breeding patterns and reproductive 
success of California sea otters. Journal of Wildlife 
Management 58:391-399. 

Siniff D.B. , and K. Ralls. 1991. Reproduction, survival, and 
tag loss in California sea otters. Marine Mammal Science 
7(3):21 1-229. 

Wendell. F.E., R.A. Hardy, and J.A. Ames. 1985. 
Assessment of the accidental take of sea otters. Enhydra 
lutris. in gill and trammel nets. Marine Research Branch. 
California Department of Fish and Game. 30 pp. 

Wilson, D.E., M.A. Bogan, R.L. Brownell. Jr.. A.M. Burdin. 
and M.K. Maminov. 1991. Geographic variation in sea 
otters. Enhydra lutris. Journal of Mammalogy 
72(l):22-36. " 



White-tailed 
Deer in the 
Northeast 



by 

Gerald L. Storm 

National Biological Service 

William L. Palmer 

Pennsylvania Game 

Commission 



Populations of white-tailed deer (Odocoileus 
virginianus) have changed significantly 
during the past 100 years in the eastern United 
States (Halls 1984). After near extirpation in the 
eastern states by 1 900, deer numbers increased 
during the first quarter of this century. The 
effects of growing deer populations on forest 
regeneration and farm crops have been a con- 
cern to foresters and farmers for the past 50 
years. 

In recent years, deer management plans have 
been designed to maintain deer populations at 
levels compatible with all land uses. Conflicts, 
however, between deer and forest management 
or agriculture still exist in the Northeast. Areas 
that were once exclusively forests are now a 
mixture of forest, farm, and urban environments 



that create increased interactions and conflicts 
between humans and deer, including deer-vehi- 
cle collisions. Management of deer near urban 
environments presents a unique challenge for 
local resource managers (Porter 1991). 

This report describes trends in abundance of 
white-tailed deer in the northeastern United 
States, relationships between harvest and popu- 
lation estimates, and conflicts between deer and 
other resources. 

Data Surveys 

We contacted biologists in each of 13 north- 
eastern states to acquire estimates of deer popu- 
lation size, harvest, and deer-vehicle collisions. 
We featured harvest data for antlered deer from 



Our Living Resources — Mammals 



113 



all 1 3 states to describe deer abundance during 
1983-92, as well as data from selected states to 
describe relations between deer harvests and 
population size. 

Biologists in the northeastern states also pro- 
vided information on trends in reported con- 
flicts between deer and land use and other nat- 
ural resources. We determined the proportion of 
states that expressed conflicts for particular cat- 
egories such as deer and agriculture, deer and 
forestry, or deer and other resources. 



Population Estimates and 
Management Implications 

White-tailed deer populations have 
increased in all 13 northeastern states during 
1983-92, based on either population estimates 
or number of antlered deer harvested. 
Population estimates for nine states indicated an 
increase from less than 1 .5 million in the early 
1980's to 1.8 million in the early 1990's (Fig. 
1). Deer density in the deer range of these states 



Even though states are responsible for 
managing deer within their boundaries, 
they do not control all land areas. The level 
of management for a state may be an eco- 
logical or political unit. However, states usu- 
ally lack data on deer and their habitats for 
small units such as municipalities, parks, 
refuges, or military facilities, and they are 
not directly responsible for management of 
these special areas. Presented here are exam- 
ples of two state parks, two national parks 
and a national historic site, and three nation- 
al wildlife refuges. 

Parks 

Ridley Creek and Tyler state parks in 
Pennsylvania provide two examples of 
where attempts have been made to manage 
high deer densities in and around urban 
areas. Such high densities pose significant 
problems because of deer feeding on orna- 
mental plants and deer-vehicle collisions. At 
Ridley Creek State Park, a 1,052-ha (2,600- 
acre) area near Philadelphia, hunters har- 
vested 97-344 deer per year during eight 
controlled hunts held between 1983 and 
1992. From 160 to 491 deer were observed 
during annual counts made from helicopters 
(no count was made in 1990). A count of 491 
in 1983 indicated that the deer density was 
in excess of 46.7 deer/km 2 (121 deer/mi 2 ) in 
the park. Hunter harvests resulted in a sig- 
nificant herd reduction, as 160 deer were 
counted in 1992 compared to 491 in 1983. 

Controlled hunts were conducted during 
4 years— 1987, 1988, 1989, and 1991— at 
Tyler State Park in eastern Pennsylvania. 
The hunts in December 1987 and January 
1988 yielded a kill of 487 deer; this number 
equates to 70.3 deer harvested per km 2 (182 
deer/mi 2 ) on the 692-ha (1,710-acre) park. 
During 1987, 455 deer were counted during 
aerial surveys compared to 49 during 1992, 
indicating that controlled hunts resulted in a 
significant reduction in deer abundance at 
Tyler State Park. 

National Parks 

The 2,335-ha (5,770-acre) Catoctin 
Mountain National Park, administered by 
the National Park Service in Maryland, has 



Deer Management at 
Parks and Refuges 



been noticeably affected by deer since at 
least 1981. Estimates of deer density indicat- 
ed an increase from 9.6 to 23.5 deer/km 2 (25 
to 61 deer/mi 2 ) between 1986 and 1989. The 
presence of deer at this density has led to 
concern over the effect of deer on native 
plants, including rare species. The National 
Park Service is preparing an environmental 
assessment to review various management 
alternatives and to select a strategy to man- 
age deer at Catoctin Mountain Park. Unlike 
in state parks, harvest of deer from National 
Park Service lands is difficult, if not illegal, 
to implement; hence, management options 
are more limited. 

Estimates of deer abundance at 
Gettysburg National Military Park and 
Eisenhower National Historic Site from 
1987 through 1992 indicated an increase 
from 721 to 1,018 deer on a 2,862-ha (7,072- 
acre) area near Gettysburg in Adams County, 
Pennsylvania (Storm et al. 1992; Tzilkowski 
and Storm 1993). The 1992 population 
equates to a density of 35.5 deer/km 2 (92 
deer/mi 2 ), which is 10 times higher than that 
prescribed by the Pennsylvania Game 
Commission for Adams County. The deer 
herd at Gettysburg has been associated with 
high levels of damage to farm crops and for- 
est plant communities, as well as deer-vehi- 
cle collisions. An environmental impact 
statement is being prepared to develop a 
strategy for managing the Gettysburg deer 
population. 

Refuges 

The number of deer harvested by hunters 
increased twofold between 1983 and 1992 at 
each of the three national wildlife refuges 
examined. During 1992, the number of deer 
taken by hunters was 165 (17.8/km 2 
[46/mi 2 ]) for Eastern Neck, 210 (7.7/km 2 
[20/mi 2 ]) for Great Swamp, and 109 
(4.2/km 2 [1 1/mi 2 ]) at Montezuma. Although 



we did not obtain estimates of prehunt pop- 
ulations at these three refuges, if we assume 
that 35% of the population was killed, the 
prehunt herd size at the Great Swamp 
Refuge was 600 deer, which equates to 22 
deer/km 2 (57 deer/mi 2 ). 

Harvests by hunters appear to control 
deer at national wildlife refuges, despite the 
fact that each refuge manager has a unique 
set of cultural and biological attributes to 
consider in deer management. Although 
hunting is a viable deer management alter- 
native for most refuges, there is still a need 
to monitor the size of deer herds, determine 
the most suitable technique to survey deer at 
each refuge and the most useful demograph- 
ic data, and monitor plant communities to 
assess the effect of feeding by deer on plant 
resources. 




White-tailed deer fawn. 



References 



Storm, G.L., D.F. Cottam, R.H. Yahner, and J.D. 
Nichols. 1992. A comparison of two techniques 
for estimating deer density. Wildlife Society 
Bull. 20:197-203. 

Tzilkowski, W.M., and G.L. Storm. 1993. 
Detecting change using repeated measures 
analysis: white-tailed deer abundance at 
Gettysburg National Military Park. Wildlife 
Society Bull. 21:411-414. 



114 



Mammals — Our Living Resources 



2.0 




83 84 85 86 87 88 89 90 91 92 
Year 
Fig. 1. The trend in the size of the 
white-tailed deer population in 
nine northeastern states 
(Connecticut, Delaware, Maine, 
Massachusetts, New Hampshire, 
New York, Pennsylvania, Rhode 
Island, Vermont), 1983-92. 



Fig. 2. The harvest of antlered 
white-tailed deer (number per 
square mi or 259 ha of deer range) 
in 13 northeastern states in 1983 
(first value) and in 1992 (second 
value); estimates for Virginia and 
West Virginia include young-of- 
the-year males (button bucks). 



has increased from 4.3 deer/km 2 (11.1 
deer/mi 2 ) in 1983 to 5.5 deer/km 2 (14.2 
deer/mi 2 ) in 1992. Density estimates ranged 
from 2.7 deer/km 2 (7.1 deer/mi 2 ) in Rhode 
Island to 9.7 deer/km 2 (25.1 deer/mi 2 ) in 
Pennsylvania. The total 1992 population of 
white-tailed deer in the Northeast (including 
estimates provided by personal communication 
with biologists from Maryland, New Jersey, 
Virginia, and West Virginia) was estimated at 
about 3.0 million. 

The total antlered (Fig. 2) and antlerless har- 
vest for all 1 3 states was estimated at 600,000 in 
1983 and 900,000 in 1992. Managers manipu- 
late the harvest of antlered to antlerless deer to 
obtain a desired population (i.e., appropriate 
age and sex ratios). During the past decade, deer 
populations in the Northeast have continued to 
increase except in states that harvested marked- 
ly more antlerless than antlered deer. In 
Pennsylvania, for example, the deer population 
increased until the harvest of antlerless deer 
reached levels necessary to curb the upward 
trend in the population. In contrast, 
Massachusetts has consistently harvested more 
antlered than antlerless deer and the population 




1983 value/1992 value 



continues to increase. These two examples illus- 
trate how a prescribed harvest of antlerless deer 
can be used to achieve a population response 
that is consistent with each state's management 
objective. The magnitude of the antlerless and 
antlered deer harvest is a key factor for adjust- 
ing populations. The actual female-male ratio in 
the population, reproductive rates, and the sex- 
specific mortality caused by nonhunting factors 
also affect the population trends of each state. 
Ten of 1 3 states responded to the request for 




White-tailed deer (Odocoileus virginianus). 

information on deer conflicts during the past 
decade; only two of these indicated no conflict 
between current deer populations and land use 
or other natural resources. Four of the eight 
states with conflicts indicated increasing trends 
in agriculture-deer conflicts. Conflicts increased 
between deer and urban habitats in eight states, 
and vehicle-deer collisions increased in seven of 
the states. Seven states indicated they had prob- 
lems between deer and forest regeneration, and 
two of these states indicated the problem was 
becoming commoner. Seven states reported deer 
conflicts with parks and refuges; such problems 
included lack of forest regeneration as well as 
deer feeding on ornamental shrubs on private 
property. Four of these states indicated increas- 
ing trends in these kinds of problems. 

Conclusions and Present 
Outlook 

The trends in abundance of deer in north- 
eastern states are largely a function of regulated 
harvests by hunters. A significant amount of 
information on annual harvest by hunters and 
deer demographics is available in each north- 
eastern state. Thus, the process of managing 
white-tailed deer may serve as a model to eval- 
uate monitoring techniques, population dynam- 
ics, and effects of wildlife on cultural and other 
natural resources. 

Managers of parks and refuges need better 
information to predict trends in regeneration 
and development of forests and the role of deer 
in forest regeneration. This will require the use 
of new and appropriate survey techniques 
(Wiggers and Beckerman 1993) and the ability 
to evaluate, interpret, and manage data acquired 
during long-term monitoring of deer and habi- 
tats used by deer (Tzilkowski and Storm 1993). 
Management goals can only be achieved 
through knowledge of trends in deer abundance 



Our Living Resources — Mammals 



115 



and a better understanding of public attitudes 
toward natural resources. 

References 

Halls, L.K., ed. 1984. White-tailed deer: ecology and man- 
agement. Stackpole Books, Harrisburg, PA. 870 pp. 

Porter, W.F. 1991. White-tailed deer in eastern ecosystems: 
implications for management and research in national 
parks. Natural Resources Report NPS/NRSUNY/NRR- 
91/05, National Park Service, Denver, CO. 57 pp. 



Tzilkowski, W.M., and G.L. Storm. 1993. Detecting change 
using repeated measures analysis: white-tailed deer 
abundance at Gettysburg National Military Park. Wildlife 
Society Bull. 21:411-414. 

Wiggers, E.P., and S.F. Beckerman. 1993. Use of thermal 
infrared sensing to survey white-tailed deer populations. 
Wildlife Society Bull. 2 1 :263-268. 



For further information: 

Gerald L. Storm 

National Biological Service 

Pennsylvania Cooperative Fish 

and Wildlife Research Unit 

University Park, PA 16802 



North American elk or wapiti (Cervus ela- 
phus) represent how a wildlife species can 
recover even after heavy exploitation of popula- 
tions and habitats around the turn of the centu- 
ry. This species is highly prized by wildlife 
enthusiasts and by the hunting public, which 
has provided the various state wildlife agencies 
with ample support to restore populations to 
previously occupied habitats and to manage 
populations effectively. Additionally, the Rocky 
Mountain Elk Foundation, founded in 1984, has 
promoted habitat management, acquisition, and 
proper hunting ethics among many segments of 
the hunting public. 

Current population size is estimated at 
782,500 animals for the entire elk range (Rocky 
Mountain Elk Foundation 1989). Projections of 
population trends for the national forests and for 
the entire U.S. elk range are for continued 
increases through the year 2040 (Flather and 
Hoekstra 1989). 

This species occupies more suitable habitat 
than at any time in the century, and populations 
are at all-time highs (Figure). Elk populations in 
the United States primarily occupy federally 
managed lands, including national forests, pub- 
lic lands, national parks, and several wildlife 
refuges. Substantial populations occur on pri- 
vate holdings, including large ranches and 
reservations owned by Native Americans. 
Populations have been introduced into 
Michigan and Pennsylvania and recently have 
expanded in Nevada and California. In Canada, 
elk have increased their range into northern 
British Columbia since 1950 and occupy crown 
lands in Alberta, British Columbia, and 
Manitoba. Elk populations in the mountain 
parks of Jasper, Yoho, Kootenay, and Banff are 
an important part of the fauna, and the popula- 
tions in Elk Island National Park and Riding 
Mountain National Park have been extensively 
investigated. In Alberta and the western United 
States, an industry centered around ranching elk 
has proliferated in recent years. 

Perhaps the most spectacular improvement 
in elk populations is in California, where one 
population that originally consisted of about 
600 individuals in the Owens Valley has now 
grown to over 2,500 Tule elk in 22 different 



populations (Phillips 1993). Aquiring habitat 
and reintroducing elk are the major reasons for 
the increase. 

Problems associated with elk management 
include the reduced life expectancies of males, 
which in some areas are attributable to hunting. 
This problem has been aggravated by increased 
access to formerly inaccessible habitat, allow- 
ing more bulls to be hunted. Additionally, elk 
have moved into more accessible habitats that 
provide less cover during hunting seasons. In 
some cases, hunting has increased enough to 
lower bull elk life expectancies even in areas 
where access has not increased. Means to 
address these issues include reductions in sea- 
son lengths, quotas on bulls either through 
hunter registration or limited-entry permit 
hunts, closures of extensive areas to vehicle 
access during the hunting season, and more 
integrated management of timber harvest to 
accommodate the needs of elk for escape cover. 

Such restrictions vary in their effectiveness, 
depending upon numbers and distribution of 
hunters, other human disturbances, and the 
amount and kind of forest involved. In open 
pine forests, for example, restricting access 
may be less effective than in denser fir forests, 
making other hunting regulations, such as limit- 
ed-entry hunts, necessary. Elk occupying open 
rangelands where conifer cover is poorly dis- 
tributed are largely subject to limited-entry 
hunting. Elk are sensitive to human activity 




North 
American Elk 



by 

James M. Peek 

University of Idaho 




Figure. Distribution of elk in 
North America as of 1978. based 
on information provided by 
provincial and state wildlife agen- 
cies (modified from Thomas and 
Toweill 1982, used with permis- 
sion, Wildlife Management 
Institute). 



116 



Mammals — Our Living Resources 



For further information: 

James M. Peek 

University of Idaho 

Department of Fish and Wildlife 

Resources 

Moscow, ID 83843 



even in national parks where they are not hunt- 
ed and may become partially conditioned to 
human presence. Recreational, logging, graz- 
ing, seismic, and mining activities must be 
restricted to times and places where animals are 
least affected. 

As elk numbers have increased in farming 
areas, depredation on cash crops has also 
increased. Efforts to address this issue include 
special "depredation" hunts designed to move 
animals away from problem areas or to reduce 
populations, planting less palatable crops, fenc- 
ing hay and valuable crops to prevent access by 
elk, feeding elk, and hazing to discourage use. 
An integrated and specially tailored approach is 
often necessary to address this important prob- 
lem. 

Whether the high densities of elk that occur 
within Yellowstone National Park are perceived 
to be a problem depends upon one's viewpoint. 
Current research on the condition of park plant 
communities heavily used by wintering elk sug- 
gests that factors interact to influence these 
communities. Grasslands that have been pro- 
tected for more than 30 years did not exhibit 
changes in productivity when compared with 
grazed grasslands (Coughenour 1991). On the 
other hand, when protected stands are compared 
with stands open to browsing, it appears that 
woody plants may have been adversely altered 
through prolonged heavy grazing (Chadde and 
Kay 1991). Past actions that affected plants 
include fire protection, concentrated grazing 
pressure by bison (Bison bison) in some areas, 
and altered grizzly bear (Ursus arctos) feeding 
behavior. Within Yellowstone Park, the prospec- 
tive restoration of wolf (Canis lupus) popula- 
tions and changes in grizzly bear populations 
since the elimination of artifical food sources 
will undoubtedly affect elk populations that 
exist primarily within the park. 

Natural changes in habitat across the west- 
ern elk range have largely benefited elk. Efforts 
to improve range conditions by modifying live- 
stock grazing practices will provide more for- 
age for elk, even if losses in woody plants may 
reduce the habitat quality for deer. Better live- 
stock management should also mean accommo- 
dating elk habitat use by providing ungrazed 
pastures within grazing allotments and by 



manipulating livestock grazing so plants retain 
their palatability to elk. As livestock is managed 
more effectively across western public lands, 
forage plants that wildlife use will benefit, thus 
also benefiting elk. 

On the other hand, some traditional 
high-quality elk winter habitats, which contain 
serai (see glossary) shrub ranges that developed 
after large fires earlier this century, are now 
growing into conifer stands. Some conifers like 
Douglas fir (Pseudotsuga menziesii) are palat- 
able and highly digestible for elk, and even 
pole-size stands can provide needed cover dur- 
ing severe winters or hunting seasons. As 
conifers dominate a larger proportion of the 
winter ranges and associated spring habitats, 
however, they shade out other species and habi- 
tat quality may deteriorate, eventually hurting 
elk populations. These long-term changes are 
not easily dealt with in short-term management 
efforts. 

Nevertheless, the future of elk populations in 
North America seems secure. Demand for hunt- 
ing as well as the nonconsumptive values of elk 
will ensure the success of substantial popula- 
tions. Elk populations will benefit from 
improved habitat conditions on arid portions of 
the range, improved livestock management, 
more effective integrated management of forest- 
ed habitats, and continued implementation of 
fire management policies in the major wilder- 
ness areas and national parks. 

References 

Chadde, S.W., and C.E. Kay. 1991. Tall willow communi- 
ties on Yellowstone's northern range: a test of the "natur- 
al regulation" paradigm. Pages 231-262 in R.B. Keiter 
and M.S. Boyce. eds. The greater Yellowstone ecosys- 
tem. Yale University Press, New Haven, CT. 

Coughenour, M.B. 1991 . Biomass and nitrogen responses to 
grazing of upland steppe on Yellowstone's northern win- 
ter range. Journal of Applied Ecology 28:71-82. 

Rather, C.H., and T.W. Hoekstra. 1989. An analysis of the 
wildlife and fish situation in the United States: 
1989-2040. U.S. Department of Agriculture Forest 
Service Gen. Tech. Rep. RM-178. 147 pp. 

Phillips. B. 1993. Good news for tules: Destanella Flat. 
Bugle 10:21-31. 

Rocky Mountain Elk Foundation. 1989. Wapiti across the 
West. Bugle 6:138-140. 

Thomas. J.W.. and D.E. Toweill, eds. 1982. Elk of North 
America. Stackpole Books. Harrisburg, PA. 698 pp. 



«**R 



.-*?i 



Reptiles and Amphibians 




Overview 



Amphibians and reptiles 
are important elements of 
our national biological heritage and deserve 
special attention. They are crucial to the natural 
functioning of many ecological processes and 
key components of important ecosystems. In 
some areas certain species are economically 
consequential; others are aesthetically pleasing 
to many people, and as a group they represent 
significant segments of the evolutionary history 
of North America. Knowledge gained from past 
study of amphibian development and metamor- 
phosis has contributed immensely to our under- 
standing of basic biological processes and has 
directly benefited humans. 

The native herpetofauna of the continental 
United States includes about 230 species of 
amphibians (about 62% of which are salaman- 
ders and 38% frogs) and some 277 species of 
reptiles (about 19% turtles, 35% lizards, 45% 
snakes, and less than 1% crocodilians). If the 
list were expanded to include native species 
from Puerto Rico and the U.S. Virgin Islands in 
the Caribbean, Hawaii, the Trust Territory of the 
Pacific Islands, and the U.S. Territories in the 
Pacific, the amphibian list would increase by 
about 20 native species (all frogs) and another 5 
non-native frog species. If the reptile inventory 
were expanded similarly, the list would increase 



by 2 turtles, 83 lizards, 18 snakes, and 1 croco- 
dilian. Another 2 species of turtles, 17 lizards, 2 
snakes, and 1 crocodilian have been introduced. 
An updated summary of this information is 
scheduled for publication later this year 
(McDiarmid, unpublished data). 

Many U.S. reptile and amphibian checklists 
and field guides have been written over the past 
50 years. The data for such summaries come 
from researchers working with various aspects 
of the biology of amphibians and reptiles and 
are found in many scientific publications. These 
summary field guides give the impression that 
the herpetofauna of the United States is well 
known and well studied. When we realize how 
little is known of the herpetofauna of compara- 
ble areas in South America, such an assumption 
is valid. A cursory review of U.S. data, howev- 
er, provides a somewhat different view. Since 
1978 the total herpetofaunal diversity of the 
United States has increased by almost 12%, 
from 454 to 507 species. Much of that increase, 
though, has resulted from a new knowledge of 
complex groups of species (e.g., eastern pletho- 
dontid salamanders) through the application of 
molecular techniques to gain a better under- 
standing of the patterns of species formation 
and of the phylogenetic (evolutionary) history 
of certain groups. New species are still being 



by 
Science Editor 

Roy W. McDiarmid 

National Biological 

Service 
National Museum of 

Natural History 
Washington, DC 20560 



118 



Reptiles and Amphibians — Our Living Resources 



discovered in relatively populated parts of the 
country (e.g., salamanders from California; D. 
Wake, Museum of Vertebrate Zoology, 
University of California, Berkeley, personal 
communication). 

Baseline information of the status and health 
of U.S. populations of amphibians and reptiles 
is remarkably sparse. No national program of 
monitoring populations of amphibians and rep- 
tiles, comparable to the North American 
Breeding Bird Survey (now coordinated by the 
National Biological Service), is operational. 
Programs in some states (e.g., Kansas, Illinois, 
Maryland, Wisconsin) have been moderately 
successful in monitoring amphibians, but clear- 
ly a national program is needed. Long-term data 
(more than 10 years) from specific sites in many 
habitats in different parts of the country were 
and are essential to detect continental or global 
patterns of change in the distribution and abun- 
dance of species' populations. A recent publica- 
tion (Heyer et al. 1994) recommended standard 
guidelines and techniques for monitoring 
amphibian populations and habitats; a similar 
volume on reptiles is planned. What remains is 
to establish a national program for such moni- 
toring studies; the Declining Amphibian 
Populations Task Force, a part of the Species 
Survival Commission of the World 
Conservation Union, together with the National 
Biological Service, should play major roles in 
establishing such programs for amphibians. 
Similarly, organizations that deal with the con- 
servation of turtles and crocodilians need to be 
expanded to develop an effective national mon- 
itoring program for reptiles. 

Habitat degradation and loss seem to be the 
most important factors adversely affecting 
amphibian and reptile populations in North 
America. The drainage and loss of small aquat- 
ic habitats and their associated wetlands have 
had a major adverse effect on many amphibian 
species and some reptiles. 

Many other factors in the decline of reptiles 
and amphibians have been implicated; most, 
perhaps all, are human-caused. For example. 



non-native species of gamefish introduced for 
sport have been implicated in the decline of frog 
populations in mountainous areas of some west- 
ern states. Similarly, the introduction, acciden- 
tal or intentional, of other non-native species 
(e.g., bullfrogs in western states, anoline lizards 
in south Florida, and snakes in Guam) has 
harmed native species in other parts of the coun- 
try. Although populations of a few species have 
been severely impacted for diverse reasons (see 
the articles on California native frogs and the 
Tarahumara frog [Rana tarahumarae]), it is not 
too late to prevent the extirpation of others. 
Certain management and conservation deci- 
sions based on adequate scientific data and 
careful planning have proven successful {see 
articles on Coachella Valley fringe-toed lizard 
[Uma inomata] and the American alligator 
[Alligator mississippiensis]), but too often these 
initiatives are reactive and occur only after a 
species is in trouble. 

Clearly, a better coordinated national pro- 
gram that looks at all species of amphibians and 
reptiles is desirable. Local and state programs to 
monitor amphibian and reptile populations are 
beginning; these efforts need to be expanded 
nationally. It is obvious that early detection of 
problems is crucial to successful remedial 
action. In many ways, a national program of 
monitoring amphibian and reptile populations is 
like preventive medicine; the earlier a problem 
is detected, the greater the likelihood of suc- 
cessful treatment and the lower the cost. A 
proactive national program based on standard- 
ized scientific methodology and applied across 
all species and habitats will go a long way 
toward ensuring that amphibians and reptiles 
remain a healthy component of our national bio- 
logical heritage. They are too important overall 
to receive anything less. 

Reference 

Heyer, W.R., M.A. Donnelly. R.W. McDiarmid. L.-A.C. 
Hayek, and M.S. Foster, eds. 1994. Measuring and mon- 
itoring biological diversity: standard methods for 
amphibians. Smithsonian Institution Press. Washington. 
DC. 364 pp. 



Turtles 



by 

Jeffrey E. Lovich 

National Biological Service 



Turtles have existed virtually unchanged for 
the last 200 million years. Unfortunately, 
some of the same traits that allowed them to 
survive the ages often predispose them to 
endangerment. Delayed maturity and low and 
variable annual reproductive success make tur- 
tles unusually susceptible to increased mortality 
through exploitation and habitat modifications 
(Brooks et al. 1991; Congdon et al. 1993). 

In general, turtles are overlooked by wildlife 
managers in spite of their ecological signifi- 
cance and importance to humans. Turtles are, 
however, important as scavengers, herbivores, 



and carnivores, and often contribute significant 
biomass to ecosystems. In addition, they are an 
important link in ecosystems, providing disper- 
sal mechanisms for plants, contributing to envi- 
ronmental diversity, and fostering symbiotic 
associations with a diverse array of organisms. 
Adults and eggs of many turtles have been used 
as a food resource by humans for centuries 
(Brooks et al. 1988; Lovich 1994). As use pres- 
sures and habitat destruction increase, manage- 
ment that considers the life-history traits of tur- 
tles will be needed. 



Our Living Resources — Reptiles and Amphibians 



119 



Documenting Turtle Population 
Status 

I reviewed the population trends of turtles in 
the United States by examining most references 
(Ernst et al. 1994) that document the trends of 
turtle species and populations. Because few 
long-term studies (lasting more than one gener- 
ation of the species examined) have focused on 
turtles, data on population fluctuations over 
time are generally unavailable (but see Gibbons 
1990; Congdon et al. 1993). Techniques for 
conducting population studies of turtles and 
analyzing the data are summarized in Gibbons 
(1990). 

Although we know less than desired about 
the actual extent of population fluctuations in 
most turtle populations, we do know that many 
turtles in the United States are at great risk of 
decline and extinction. Of the 55 native turtle 
species in the United States and its offshore 
waters, 25 (45%) require conservation, and 21 
(38%) are protected or are candidates for pro- 
tection under the Endangered Species Act. Of 
the 1 1 species and subspecies listed as candi- 
dates for protection under the ESA, 4 are con- 
sidered declining, and 7 have unknown popula- 
tion statuses (Table). All tortoises and marine 



turtles require conservation action. Of the 
remaining 46 turtle species (aquatic and semi- 
aquatic forms), 16 (35%) require conservation 
action. The percentage of U.S. turtles requiring 
conservation action (45%) is similar to that of 
the world (41%; IUCN/SSC Tortoise and 
Freshwater Turtle Specialist Group 1991). 

Although no turtles in the United States are 
known to have become extinct since European 
colonization (Honegger 1980), many species 
have experienced significant declines in num- 
bers and distribution during the last 100 years. 
For example, several bog turtle (Clemmys muh- 
lenbergii) populations in western New York, 
and all populations in western Pennsylvania, are 
apparently extirpated (Collins 1990; Ernst et al. 
1994). Some populations of the spotted turtle 
(C. guttata) have also shown dramatic declines 
(Lovich 1989). Even wide-ranging, formerly 
common species such as the common box turtle 
(Terrapene Carolina; Ernst et al. 1994), desert 
tortoise (Gopherus agassizii; USFWS 1993), 
gopher tortoise (G. polyphemus; McCoy and 
Mushinsky 1992), common slider (Trachemys 
scripta; Warwick 1986), and the alligator snap- 
ping turtle (Macroclemys temminckii; Pritchard 
1989) have declined significantly, underscoring 
the importance of monitoring "common" 



Family and species 


Common name 


Status* 


Cheloniidae 


Sea turtles 




Caretta caretta 


Loggerhead 


Threatened 


Chelonia mydas 


Green sea turtle 


Endangered or threatened according to population or geographic area 


Eretmochelys imbricata 


Hawksbill 


Endangered 


Lepidochelys kempii 


Kemp's ridley 


Endangered 


L olivacea 


Olive ridley 


Endangered or threatened according to population or geographic area 


Chelydridae 


Snapping turtles 




Macroclemys temminckii 


Alligator snapping turtle 


Unknown but vulnerable; C 2 candidate 


Dermochelyidae 


Leatherback sea turtles 




Dermochelys coriacea 


Leatherback 


Endangered 


Emydidae 


Semi-aquatic pond turtles 




Clemmys insculpta 


Wood turtle 


May become threatened if trade not brought under control 


C. marmorata 


Western pond turtle 


Declining; C 2 candidate 


C. muhlenbergii 


Bog turtle 


Unknown; are or may be threatened by international trade; C 2 candidate 


Emydoidea blandingii 


Blanding's turtle 


Declining; C 2 candidate 


Graptemys barbouri 


Barbour's map turtle 


Unknown; C 2 candidate 


G. caglei 


Cagle's map turtle 


Unknown 


G. flavimaculata 


Yellow-blotched map turtle 


Threatened, but insufficiently known; may be threatened by international trade 


G. oculifera 


Ringed map turtle 


Threatened; restricted distribution 


Malaclemys terrapin 


Diamondback terrapin 


Some populations unknown, others declining; C 2 candidate; listing 
applies to population or geographic area 


Pseudemys alabamensis 


Alabama red-bellied turtle 


Endangered; restricted distribution 


P. rubriventris 


Red-bellied turtle 


Endangered, according to population or geographic area 


Kinosternidae 


Mud and musk turtles 




Kinosternon flavescens 


Yellow mud turtle 


Unknown; C 2 candidate; listing applies to population or geographic area 


K. hirtipes 


Mexican rough-footed mud turtle 


Unknown; C 2 candidate; listing applies to population or geographic area 


Sternotherus depressus 


Flattened musk turtle 


Threatened 


Testudinidae 


Tortoises 




Gopherus agassizii 


Desert tortoise 


Some populations threatened, others are C 2 candidates; may become threatened 
if trade not brought under control. Status of Sonoran Desert population unknown 


G. berlandieri 


Texas tortoise 


May become threatened if trade not brought under control 
Receiving some conservation action 


G. polyphemus 


Gopher tortoise 


Declining. Some populations threatened, others are C 2 candidates; may become 
threatened if trade not controlled. Receiving some conservation action 


Trionychidae 


Softshell turtles 




Apalone spinifera 


Spiny softshell turtle 


Are or may be affected by international trade 



Table. U.S. turtle species in need 
of conservation. 



C 2 Possibly qualifying for threatened or endangered status, but more information is needed for determination. 



120 



Reptiles and Amphibians — Our Living Resources 




Barbour's map turtle (Graptemys barbouri) is restricted to the Apalachicola River system of 
Alabama, Florida, and Georgia. The species is a candidate for listing under the Endangered 
Species Act. 

species (Dodd and Franz 1993). The alarming 
decline of marine turtle populations is discussed 
later in this section. 

Perhaps the best data on long-term popula- 
tion changes in turtles are for the diamondback 
terrapin {Malaclemys terrapin), a species 
exploited heavily during the 19th century as a 
gourmet food (McCauley 1945; Carr 1952). 
Terrapin populations declined rapidly, causing 
some states to set seasons and limits for their 
protection as early as 1878. The market for ter- 
rapin meat eventually waned, and terrapin pop- 
ulations recovered somewhat because their 
habitat remained largely intact. Unfortunately, 
some terrapin populations may be declining 
again because of renewed regional harvesting 
(Garber 1988), increased habitat destruction, 
mortality from vehicles, and drowning in crab 
traps (Ernst et al. 1994). 

Some turtle species, such as members of the 
map turtle genus Graptemys, have restricted 
ranges (Lovich and McCoy 1992) that place 
them at extreme risk of extinction. In addition, 
the popularity of many species, particularly tor- 
toises, as pets, contributes to the decline of wild 
populations (IUCN/SSC 1989; Ernst et al. 
1994). Disease also appears to contribute to 
population declines in some turtles (Balazs 
1986; Dodd 1988; Jacobson et al. 1991) and 
even seems a major challenge to the recovery of 
the federally threatened desert tortoise (USFWS 
1993). 

Because of individual longevity, delayed 
maturity, and long generation times of turtles, 
long-term studies are required to monitor the 
dynamics of turtle populations (Gibbons 1990); 
recovery of most threatened species will be 



slow. Programs in which hatchlings are propa- 
gated in captivity and later released into the 
wild will do little to assist the recovery of turtles 
until the ultimate causes of decline are correct- 
ed (Frazer 1992). 

Efforts to conserve turtles in the United 
States should be concentrated in areas of high 
species diversity, where many species have lim- 
ited distributions, and where populations are at 
great risk. Notable high-risk areas include shal- 
low wetlands inhabited by freshwater turtles 
and coastal zones occupied by sea turtles. The 
most significant area of turtle endemism in the 
United States is along the Coastal Plain of the 
Gulf of Mexico (Lovich and McCoy 1992). 
Eleven species of turtles in the southeastern 
United States, where diversity is high (Iverson 
and Etchberger 1989; Iverson 1992). require 
conservation action, adding to the importance 
of implementing immediate conservation pro- 
grams in that region. 

References 

Balazs. G.H. 1986. Fibropapillomas in Hawaiian green tur- 
tles. Marine Turtle Newsletter 39: 1-3. 

Brooks, R.J., G.P. Brown, and D.A. Galbraith. 1991. Effects 
of a sudden increase in natural mortality of adults on a 
population of the common snapping turtle (Chelydra ser- 
pentina). Canadian Journal of Zoology 69:1314-1320. 

Brooks, R.J.. D.A. Galbraith. E.G. Nancekivell, and C.A. 
Bishop. 1988. Developing guidelines for managing snap- 
ping turtles. Pages 174-179 in R.C. Szaro, K.E. Severson. 
and D.R. Patton, tech. coords. Management of amphib- 
ians, reptiles, and small mammals in North America. 
U.S. Forest Service Gen. Tech. Rep. RM-166. 

Carr, A.F. 1952. Handbook of turtles. The turtles of the 
United States. Canada, and Baja California. Comstock 
Publishing Associates. Cornell University Press. Ithaca. 
NY. 542 pp. 

Collins. D.E. 1990. Western New York bog turtles: relicts of 
ephemeral islands or simply elusive? Pages 151-153 in 
R.S. Mitchell, C.J. Sheviak. and D.J. Leopold, eds. 
Ecosystem management: rare species and significant 
habitats. Proceedings of the Fifteenth Annual Natural 
Areas Conference. New York State Museum Bull. 471. 

Congdon. J.D.. A.E. Dunham, and R.C. Van Loben Sels. 
1993. Delayed sexual maturity and demographics of 
Blanding's turtles (Emydoidea blandingtff. implications 
for conservation and management of long-lived organ- 
isms. Conservation Biology 7:826-833. 

Dodd. C.K.. Jr. 1988. Disease and population declines in the 
flattened musk turtle Stemotherus depressus. American 
Midland Naturalist 1 19:394-401. 

Dodd, C.K., Jr.. and R. Franz. 1993. The need for status 
information on common herpetofaunal species. 
Herpetological Review 24:47-49. 

Emst. C.H.. J.E. Lovich. and R.W. Barbour. 1994. Turtles of 
the United States and Canada. Smithsonian Institution 
Press, Washington. DC. In press. 

Frazer. N.B. 1992. Sea turtle conservation and halfway 
technology. Conservation Biology 6:179-184. 

Garber. S.B. 1988. Diamondback terrapin exploitation. 
Plastron Papers 17(6): 18-22. 

Gibbons. J.W., ed. 1990. Life history and ecology of the 
slider turtle. Smithsonian Institution Press. Washington. 
DC. 368 pp. 

Honegger, R.E. 1980. List of amphibians and reptiles either 
known or thought to have become extinct since 1600. 
Biological Conservation 19:141-158. 



Our Living Resources — Reptiles and Amphibians 



121 



IUCN/SSC. 1989. The conservation biology of tortoises. 
Occasional Papers of the International Union for the 
Conservation of Nature and Natural Resources, Species 
Survival Commission (SSC) 5. 204 pp. 

IUCN/SSC Tortoise and Freshwater Turtle Specialist 
Group. 1991. Tortoises and freshwater turtles: an action 
plan for their conservation. 2nd ed. International Union 
for the Conservation of Nature and Natural Resources, 
Gland, Switzerland. 48 pp. 

Iverson, J.B. 1992. Global correlates of species richness in 
turtles. Herpetological Journal 2:77-81. 

Iverson. J.B., and C.R Etchberger. 1989. The distributions 
of the turtles of Florida. Florida Scientist 52:119-144. 

Jacobson, E.R., J.M. Gaskin, M.B. Brown, R.K. Harris, 
C.H. Gardiner, J.L. LaPoite, H.P. Adams, and C. 
Reggiardo. 1991. Chronic upper respiratory tract disease 
of free-ranging desert tortoises (Xerobates agassizii). 
Journal of Wildlife Diseases 27:296-316. 

Lovich, J.E. 1989. The spotted turtles of Cedar Bog, Ohio: 
historical analysis of a declining population. Pages 23-28 
in R.C. Glotzhober, A. Kochman, and W.T. Schultz, eds. 
Proceedings of Cedar Bog Symposium II. Ohio 
Historical Society. 

Lovich, J.E. 1994. Biodiversity and zoogeography of non- 
marine turtles in Southeast Asia. Pages 381-391 in S.K. 



Majumdar, F.J. Brenner, J.E. Lovich, J.F. Schalles, and 
E.W. Miller, eds. Biological diversity: problems and 
challenges. Pennsylvania Academy of Science, Easton. 
PA. In press. 

Lovich, J.E., and C.J. McCoy. 1992. Review of the 
Graptemys pulchra group (Reptilia, Testudines, 
Emydidae), with descriptions of two new species. Annals 
of Carnegie Museum 61:293-315. 

McCauley, R.H. 1945. The reptiles of Maryland and the 
District of Columbia. Privately printed, Hagerstown, 
MD. 194 pp. 

McCoy, E.D.. and H.R. Mushinsky. 1992. Studying a 
species in decline: changes in populations of the gopher 
tortoise on federal lands in Florida. Florida Scientist 
55:116-124. 

Pritchard, P.C.H. 1989. The alligator snapping turtle: biolo- 
gy and conservation. Milwaukee Public Museum. WI. 
104 pp. 

USFWS. 1993. Draft recovery plan for the desert tortoise 
(Mojave population). U.S. Fish and Wildlife Service, 
Portland, OR. 170 pp. 

Warwick, C. 1986. Red-eared terrapin farms and conserva- 
tion. Oryx 20:237-240. 



For further information: 

Jeffrey E. Lovich 

National Biological Service 

Midcontinent Ecological Science 

Center 

Palm Springs Field Station 

63-500 Garnet Ave. 

PO Box 2000 

North Palm Springs, CA 

92258 



Five species of marine turtles frequent the 
beaches and offshore waters of the south- 
eastern United States: loggerhead (Caretta 
caretta), green (Chelonia mydas), Kemp's rid- 
ley (Lepidochelys kempii), leatherback 
(Dermochelys coriacea), and hawksbill 
(Eretmochelys imbricata). All five are reported 
to nest, but only the loggerhead and green turtle 
do so in substantial numbers. Most nesting 
occurs from southern North Carolina to the 
middle west coast of Florida, but scattered nest- 
ing occurs from Virginia through southern 
Texas. The beaches of Florida, particularly in 
Brevard and Indian River counties, host what 
may be the world's largest population of log- 
gerheads. 

Marine turtles, especially juveniles and 
subadults, use lagoons, estuaries, and bays as 
feeding grounds. Areas of particular importance 
include Chesapeake Bay, Virginia (for logger- 
heads and Kemp's ridleys); Pamlico Sound, 
North Carolina (for loggerheads); and Mosquito 
Lagoon, Florida, and Laguna Madre, Texas (for 
greens). Offshore waters also support important 
feeding grounds such as Florida Bay and the 
Cedar Keys, Florida (for green turtles), and the 
mouth of the Mississippi River and the north- 
east Gulf of Mexico (for Kemp's ridleys). 
Offshore reefs provide feeding and resting habi- 
tat (for loggerheads, greens, and hawksbills), 
and offshore currents, especially the Gulf 
Stream, are important migratory corridors (for 
all species, but especially leatherbacks). 

Most marine turtles spend only part of their 
lives in U.S. waters. For example, hatchling log- 
gerheads ride oceanic currents and gyres (giant 
circular oceanic surface currents) for many 



years before returning to feed as subadults in 
southeastern lagoons. They travel as far as 
Europe and the Azores, and even enter the 
Mediterranean Sea, where they are susceptible 
to longline fishing mortality. Adult loggerheads 
may leave U.S. waters after nesting and spend 
years in feeding grounds in the Bahamas and 
Cuba before returning. Nearly the entire world 
population of Kemp's ridleys uses a single 
Mexican beach for nesting, although juveniles 
and subadults, in particular, spend much time in 
U.S. offshore waters. 

The biological characteristics that make sea 
turtles difficult to conserve and manage include 
a long life span, delayed sexual maturity, differ- 
ential use of habitats both among species and 
life stages, adult migratory travel, high egg and 
juvenile mortality, concentrated nesting, and 
vast areal dispersal of young and subadults. 
Genetic analyses have confirmed that females 
of most species return to their natal beaches to 
nest (Bowen et al. 1992; Bowen et al. 1993). 
Nesting assemblages contain unique genetic 
markers showing a tendency toward isolation 
from other assemblages (Bowen et al. 1993); 
thus, Florida green turtles are genetically differ- 
ent from green turtles nesting in Costa Rica and 
Brazil (Bowen et al. 1992). Nesting on warm 
sandy beaches puts the turtles in direct conflict 
with human beach use, and their use of rich off- 
shore waters subjects them to mortality from 
commercial fisheries (National Research 
Council 1990). 

Marine turtles have suffered catastrophic 
declines since European discovery of the New 
World (National Research Council 1990). In a 
relatively short time, the huge nesting assem- 



Marine 
Turtles in the 
Southeast 

by 

C. Kenneth Dodd, Jr. 

National Biological Service 



122 



Reptiles and Amphibians — Our Living Resources 



blages in the Cayman Islands, Jamaica, and 
Bermuda were decimated. In the United States, 
commercial turtle fisheries once operated in 
south Texas (Doughty 1984), Cedar Keys, 
Florida Keys, and Mosquito Lagoon; these fish- 
eries collapsed from overexploitation of the 
mostly juvenile green turtle populations. Today, 
marine turtle populations are threatened world- 
wide and are under intense pressure in the 
Caribbean basin and Gulf of Mexico, including 
Cuba, Mexico, Hispaniola, the Bahamas, and 
Nicaragua. Subadult loggerheads are captured 
extensively in the eastern Atlantic Ocean and 
Mediterranean Sea. Thus, marine turtles that 
hatch or nest on U.S. beaches or migrate to U.S. 
waters are under threats far from U.S. jurisdic- 
tion. Marine turtles can be conserved only 
through international efforts and cooperation. 

Information on the status and trends of 
southeastern marine turtle populations comes 
from a variety of sources, including old fishery 
records, anecdotal accounts of abundance, 
beach surveys for nests and females, and trawl 
and aerial surveys for turtles offshore. Surveys 
for marine turtles are particularly difficult 
because most of their lives are spent in habitats 
that are not easily surveyed. Hence, most status 
and trends information comes from counting 
females and nests. Few systematic long-term 
(more than 10-20 years) surveys have been con- 
ducted; the most notable are the nesting surveys 
at Cumberland Island and adjacent barrier 
islands in Georgia (T.H. Richardson, University 
of Georgia, unpublished data), and beaches 
south of Melbourne in Brevard County, Florida 
(Ehrhart et al. 1993). Beach monitoring is fairly 
widespread in many areas of the Southeast, but 
coverage varies considerably among beaches 
and field crews. The only long-term sampling of 
lagoonal or bay populations occurs at Mosquito 
Lagoon and Chesapeake Bay. although short- 
duration surveys have sampled Florida Bay. 
Pamlico Sound, and Laguna Madre. Trawl sur- 
veys of inlets and ship channels and aerial sur- 
veys of offshore waters have been undertaken 
periodically. 

Loggerhead and Green Turtles 

The number of turtles nesting fluctuates sub- 
stantially from one year to the next, making 
interpretation of beach counts difficult. The 
Florida nesting populations of loggerheads and 
green turtles appear stable based on 12 years of 
data from east-central Florida (Ehrhart et al. 
1993; Fig. 1). The green turtle nesting popula- 
tion may be increasing because of protective 
measures over the last 20 years or so, although 
the number of nesting females is still low 
(assuming 3-5 nests per female). North of 
Florida, nesting loggerhead numbers are declin- 



ing 3%-9% a year in Georgia and South 
Carolina (National Research Council 1990). 
The main cause of mortality is drowning in 
shrimp and fish nets (National Research 
Council 1990). although turtle excluder devices 
(TEDs; Fig. 2a) have helped reduce mortality 
(Fig 2b; Henwood et al. 1992). Large juveniles 
are most susceptible to drowning, and this is a 
critical life stage in the population dynamics of 
sea turtles (Crouse et al. 1987). 

Few data are available for lagoonal turtles, 
although similar numbers have been captured in 
Mosquito Lagoon and Chesapeake Bay from 
one year to the next. Loggerhead and green tur- 
tle populations, both adult and subadult, have 
undoubtedly declined from historical levels 
because of beach development and disturbance, 
the collection of eggs, and destructive fishing 




82 83 84 85 86 87 88 89 90 91 92 93 
Nesting season (year) 




82 83 84 85 86 87 88 89 90 91 92 93 
Nesting season (year) 

Fig. 1 a. Loggerhead nest totals in south Brevard County. 
Florida. 1982-93. b. Green turtle nest totals in south 
Brevard County. Florida. 1982-93. From Ehrhart et al. 
(1993). 



Our Living Resources — Reptiles and Amphibians 



123 



practices. Most high-level nesting occurs on the 
remaining undeveloped or lightly developed 
beaches. Even there, plans for development and 
disorientation from lights pose serious and con- 
tinuing problems. 

Kemp's Ridley 

At one time, more than 40,000 females nest- 
ed in a single mass nesting (termed "arribada") 
in Tamaulipas, Mexico. Several arribadas prob- 
ably occurred each year. Since 1947 a drastic 
reduction in the number of nesting females 
caused the near extinction of this species (Ross 
et al. 1989). Today only about 400-500 turtles 
nest each year despite stringent protection of the 
nesting beach. The principal threat to this 
species is incidental take during shrimp fishing. 

Leatherback and Hawksbill 

The leatherback and hawksbill are rare 
nesters in the southeastern United States, but 
offshore waters are important for feeding, rest- 
ing, and as migratory corridors. The status and 
trends of these species in U.S. offshore waters 
are unknown, although they are severely threat- 
ened throughout the Caribbean. Leatherbacks 
are taken by trawlers or are otherwise entangled 
in nets. Hawksbills are sought, especially in 
Cuba, for their shell, which is used for jewelry 
and similar items. The solitary nesting habits of 
hawksbills make them particularly difficult to 
monitor. 

Summary 

Sea turtles are threatened by beach develop- 
ment, light pollution, ocean dumping, incidental 
take in trawl and longline fisheries, disease 
(especially fibropapillomas), and many other 
variables. Because sea turtles are long-lived 
species, trends are difficult to monitor. Present 
methods of beach monitoring are extremely 
labor-intensive, expensive, and biased toward 
one segment of the population. Very little is 
known about marine turtle life-history and habi- 
tat requirements away from nesting beaches, 
and virtually nothing is known about male tur- 
tles. Because the effectiveness of measures 
aimed at protecting turtles may not be seen for 
decades, known conservation strategies should 
be favored over unproven mitigation schemes. 
Acquiring nesting habitat should be encour- 
aged. One of the most important management 
measures to protect sea turtles, especially of the 
juvenile and subadult size class, in the south- 
eastern United States, Caribbean, and western 
Atlantic Ocean is the use of TEDs to minimize 
drowning in commercial fisheries. Mature 




Finfish opening 



Fig. 2a. Schematic of a turtle excluder device (TED). 
From Watson et al. (1986). 

females should also be protected because of 
their importance to future reproduction. 
Researchers need to identify migratory routes, 
feeding and developmental habitat, and ways to 
minimize adverse impacts during all life-histo- 
ry stages. 

References 

Bowen, B., J.C. Avise, J.I. Richardson, A.B. Meylan. D. 
Margaritoulis, and S.R. Hopkins-Murphy. 1993. 
Population structure of loggerhead turtles (Caretta caret- 
ta) in the northwestern Atlantic Ocean and 
Mediterranean Sea. Conservation Biology 7:834-844. 

Bowen, B.W., A.B. Meylan, J. P. Ross, C.J. Limpus, G.H. 
Balazs, and J.C. Avise. 1992. Global population structure 
and natural history of the green turtle (Chelonia mydas) 
in terms of matriarchal phylogeny. Evolution 46:865- 
881. 

Crouse, D.T.. L.B. Crowder, and H. Caswell. 1987. A stage- 
based population model for loggerhead sea turtles and 
implications for conservation. Ecology 68:1412-1423. 

Doughty, R.W. 1984. Sea turtles in Texas: a forgotten com- 
merce. Southwestern Historical Quarterly 88:43-70. 

Ehrhart, L.H.. W.E. Redfoot, R.D. Owen, and S.A. Johnson. 
1993. Studies of marine turtle nesting beach productivity 
in central and south Brevard County, Florida, in 1993. 
Report to Florida Department of Environmental 
Protection, Institute of Marine Research, St. Petersburg. 
20 pp. 

Henwood, T, W. Stuntz, and N. Thompson. 1992. 
Evaluation of U.S. turtle protective measures under exist- 
ing TED regulations, including estimates of shrimp 
trawler related mortality in the wider Caribbean. 
National Oceanic and Atmospheric Administration Tech. 
Memorandum NMFS-SEFSC-303. 15 pp. 

National Research Council. 1990. Decline of the sea turtles. 
Causes and prevention. National Academy Press, 
Washington, DC. 259 pp. 

Ross, J. P., S. Beavers, D. Mundell, and M. Airth-Kindree. 
1989. The status of Kemp's ridley. Center for Marine 
Conservation, Washington, DC. 51 pp. 

Watson, J.W., J.F. Mitchell, and A.K. Shah. 1986. Trawling 
efficiency device: a new concept for selective shrimp 
trawling gear. Marine Fisheries Review 48:1-9. 



° 20 



= 15 




TEDs 



No TEDs 



Fig. 2b. Incidental capture of sea 
turtles in inshore and offshore 
waters of the United States before 
and after regulations requiring the 
use of TEDs on the U.S. shrimp 
fleet. From Henwood et al. (1992). 



For further information: 

C. Kenneth Dodd, Jr. 

National Biological Service 

Southeastern Biological Science 

Center 

7920 N.W. 71 st St. 

Gainesville, FL 32653 



124 



Reptiles and Amphibians — Our Living Resources 



Amphibians 



by 

R. Bruce Bury 

P. Stephen Corn 

C. Kenneth Dodd, Jr. 

Roy W. McDiarmid 

Norman J. Scott, Jr. 

National Biological Service 



Amphibians are ecologically important in 
most freshwater and terrestrial habitats in 
the United States: they can be numerous, func- 
tion as both predators and prey, and constitute 
great biomass. Amphibians have certain physio- 
logical (e.g., permeable skin) and ecological 
(e.g., complex life cycle) traits that could justi- 
fy their use as bioindicators of environmental 
health. For example, local declines in adult 
amphibians may indicate losses of nearby wet- 
lands. The aquatic breeding habits of many ter- 
restrial species result in direct exposure of egg, 
larval, and adult stages to toxic pesticides, her- 
bicides, acidification, and other human-induced 
stresses in both aquatic and terrestrial habitats. 
Reported declines of amphibian populations 
globally have drawn considerable attention 
(Bury et al. 1980; Bishop and Petit 1992; 
Richards et al. 1993; Blaustein 1994; Pechmann 
and Wilbur 1994). 

Approximately 230 species of amphibians, 
including about 140 salamanders and 90 anu- 
rans (frogs and toads) occur in the continental 
United States. Because of their functional 
importance in most ecosystems, declines of 
amphibians are of considerable conservation 
interest. If these declines are real, the number of 
listed or candidate species at federal, state, and 
local levels could increase significantly. 
Unfortunately, because much of the existing 
information on status and trends of amphibians 
is anecdotal, coordinated monitoring programs 
are greatly needed. 

Faunal Comparisons 

North American amphibian species exhibit 
two major distributional patterns, endemic and 




Disjunct populations of same species 
O Of concern or state-protected 
■ Federally protected 
A Extirpated U.S. population of Tarahumara frog (Rana tarahumarae) 

Figure. Distribution of U.S. endemic amphibian species; those west of the 100th meridian tend 
to be more broadly dispersed. 



widespread. Endemic species (Figure) tend to 
have small ranges or are restricted to specific 
habitats (e.g., species that occur only in one 
cave or in rock talus on a single mountainside). 
Declines are documented best for endemic 
species, partly because their smaller ranges 
make monitoring easier. Populations of 
endemics are most susceptible to loss or deple- 
tions because of localized activities (Bury et al. 
1980; Dodd 1991). Examples of endemic 
species affected by different local impacts 
include the Santa Cruz long-toed salamander 
(Amby stoma macrodactylum croceum) in 
California, the Texas blind salamander 
(Typhlomolge rathbuni) in Texas, and the Red 
Hills salamander (Phaeognathus hubrichti) in 
Alabama; these three species are listed as feder- 
ally threatened or endangered. 

The number of endemic species that have 
suffered losses or are suspected of having 
severe threats to their continued existence has 
increased in the last 15 years (Table). In part, 
the increase reflects descriptions of new species 
with restricted ranges, but the accelerating pace 

Table. The number of amphibian species showing docu- 
mented or perceived declines in 1980 (Bury et al. 1980) 
and 1994. 



Distribution pattern 


Number of species 


1980 1994 


Endemic or relict 


33 52 


Widespread 


5 33 



of habitat alteration is the primary threat. 

The ranges of most endemics in the western 
states (26 species) are widely dispersed across 
the landscape. In contrast, endemics in the east- 
ern and southeastern states (25 species) tend to 
be clustered in centers of endemism, such as in 
the Edwards Plateau (Texas), Interior (Ozark) 
Highlands (Arkansas, Oklahoma), Atlantic 
Coastal Plain (Texas to Virginia), and uplands 
or mountaintops in the Appalachian Mountains 
(West Virginia to Georgia). 

Widespread species often are habitat gener- 
alists. Many were previously common, but have 
shown regional or rangewide declines (Hine et 
al. 1981; Corn and Fogelman 1984; Hayes and 
Jennings 1986; Table). Reported declines of 
widespread species often lack explanation, per- 
haps because these observations have only 
recently received general attention or because 
temporal and spatial variations in population 
sizes of many amphibians are not well under- 
stood. Some reports are for amphibians in rela- 
tively pristine habitats where human impacts 
are not apparent. 

A few examples of declines in widespread 
species illustrate the threats they face across the 
country: 



Our Living Resources — Reptiles and Amphibians 



125 



Amphibians predominate in small forest streams 
of the Pacific Northwest. Because timber is har- 
vested without adequate streamside protection, 
many populations of the tailed frog (Ascaphus 
truei) and torrent salamanders (Rhyacotriton 
spp.) have been severely affected; some popula- 
tions soon will warrant consideration for listing. 

The western toad (Bufo boreas) once was com- 
mon in the Rocky Mountains, but now occurs at 
fewer than 20% of known localities from south- 
ern Wyoming to northern New Mexico. 

Many salamander and frog populations in the 
southeastern United States have been negatively 
affected, some severely, because of degradation 
of stream habitats (e.g., the hellbender, 
Cryptobranchus alleganiensis) and conversion of 
natural pinewood and hardwood forests and asso- 
ciated wetlands (e.g., gopher frog, Rana capito) 
to plantation forestry, agriculture, and urban uses. 

Leopard frogs (Rana spp.), which are used in 
teaching and research institutions, were once 
abundant in most of the United States. 
Populations in this diverse group have declined, 
sometimes significantly, in midwestern, Rocky 
Mountain, and southwestern states. 



Causes of Declines 

No single factor has been identified as the 
cause of amphibian declines, and many unex- 
plained declines likely result from multiple 
causes. Human-caused factors may intensify 
natural factors (Blaustein et al. 1994b) and pro- 
duce declines from which local populations 
cannot recover and thus they go extinct. Known 
or suspected factors in those declines include 




Western toad (Bufo boreas). 

destruction and loss of wetlands (Bury et al. 
1980); habitat alteration, such as impacts from 
timber harvest and forest management (Corn 
and Bury 1989; Dodd 1991; Petranka et al. 
1993); introduction of non-native predators, 
such as sportftsh and bullfrogs, especially in 
western states (Hayes and Jennings 1986; 
Bradford 1989); increased variety and use of 
pesticides and herbicides (Hine et al. 1981); 
effects of acid precipitation, especially in east- 
ern North America and Europe (Freda 1986; 
Beebee et al. 1990; Dunson et al. 1992); 
increased ultraviolet radiation reaching the 
ground (Blaustein et al. 1994a); and diseases 
resulting from decreased immune system func- 
tion (Bradford 1991; Carey 1993; Pounds and 
Crump 1994). 



A Success Story: 

The Barton Springs 
Salamander 



A success story from the Edwards Plateau 
in Texas illustrates the importance of 
baseline ecological data, current science, 
and the types of partnerships essential for 
conservation of amphibians. The recently 
described Barton Springs salamander 
(Eurycea sosorum) occurs only in three 
springs within about 300 m (984 ft) of each 
other within the city limits of Austin. This 
salamander has one of the smallest known 
distributions of any North American verte- 
brate. 

Pools associated with the two primary 
springs had been developed as municipal 
swimming and wading pools, and standard 



cleaning procedures had eliminated most 
salamanders. With cooperation of city 
authorities and local volunteers, pool main- 
tenance practices detrimental to the sala- 



mander were modified, and populations of 
the salamander seem to be increasing and 
expanding their ranges within the spring sys- 
tem. 




Barton Springs salamander (Eurycea sosorum). 



126 



Reptiles and Amphibians — Our Living Resources 



For further information: 

R. Bruce Bury 

National Biological Service 

200 S.W. 35th St. 

Corvallis, OR 97333 



Amphibian populations also may vary in 
size because of natural factors, particularly 
extremes in the weather (Bradford 1983; Corn 
and Fogelman 1984). The size of amphibian 
populations may vary, sometimes dramatically, 
from year to year, so what is perceived as a 
decline may be part of long-term fluctuations 
(Pechmann et al. 1991). The effect of global cli- 
mate change on amphibians is speculative, but it 
has the potential for causing the loss of many 
species. 

Monitoring Needs 

A profound need exists for national coordi- 
nation of regional inventories and population 
studies, including a national effort to monitor 
amphibians on parks, forests, wildlife refuges, 
and other public lands. Only through long-term 
studies will better data on population changes 
through time and between sites become avail- 
able. Such data are essential to evaluating the 
status and trends of amphibian species in the 
United States. Some regional surveys and 
inventories exist but only for a few species; 
these studies should be expanded into a coordi- 
nated effort with long-term monitoring of popu- 
lations at many sites across the country as the 
goal. 

In addition, more research is needed to 
determine the impact of natural and human- 
caused factors on the different life-history 
stages and environments of amphibians. Also, 
the assumption that amphibians are good indi- 
cators needs to be tested rigorously (Pechmann 
and Wilbur 1994). Likewise, understanding the 
dynamics of populations between habitats and 
regions, and the roles amphibians play in aquat- 
ic and terrestrial ecosystems is essential. 
Detailed work on the ecology of species and the 
factors implicated in declines needs to continue. 

References 

Beebee, T.J.C.. R.J. Flower, A.C. Stevenson. S.T. Patrick, 
P.G. Appleby, C. Fletcher, C. Marsh. J. Natkanski, B. 
Rippey. and R.W. Battarbee. 1990. Decline of the natter- 
jack toad Bufo calamita in Britain: palaeoecological. 
documentary, and experimental evidence for breeding 
site acidification. Biological Conservation 53:1-20. 

Bishop. C.A., and K.E. Petit, eds. 1992. Declines in 
Canadian amphibian populations: designing a national 
monitoring strategy. Canadian Wildlife Service 
Occasional Paper 76:1-120. 

Blaustein, A.R. 1994. Chicken Little or Nero's fiddle? A 
perspective on declining amphibian populations. 
Herpetologica 50:85-97. 



Blaustein, A.R.. P.D. Hoffman, D.G. Hokit, J.M. Kiesecker. 
S.C. Walls, and J.B. Hays. 1994a. UV repair and resis- 
tance to solar UV-B in amphibian eggs: a link to popula- 
tion declines? Proceedings of the National Academy of 
Sciences 91:1791-1795. 

Blaustein, A.R.. D.B. Wake, and W.P. Sousa. 1994b. 
Amphibian declines: judging stability, persistence, and 
susceptibility of populations to local and global extinc- 
tion. Conservation Biology 8:60-71. 

Bradford, D.F. 1983. Winterkill, oxygen relations, and ener- 
gy metabolism of a submerged dormant amphibian. Rana 
muscosa. Ecology 64:1 171-1 183. 

Bradford. D.F. 1989. Allotopic distribution of native frogs 
and introduced fishes in high Sierra Nevada lakes of 
California: implication of the negative effect of fish 
introductions. Copeia 1989:775-778. 

Bradford, D.F. 1991. Mass mortality and extinction in a 
high-elevation population of Rana muscosa. Journal of 
Herpetology 5:174-177. 

Bury, R.B., C.K. Dodd. Jr., and G.M. Fellers. 1980. 
Conservation of the Amphibia of the United States: a 
review. U.S. Fish and Wildlife Service Res. Publ. 134:1- 
34. 

Carey, C. 1993. Hypothesis concerning the causes of the 
disappearance of boreal toads from the mountains of 
Colorado. Conservation Biology 7:355-362. 

Corn, P.S., and R.B. Bury. 1989. Logging in western 
Oregon: responses of headwater habitats and stream 
amphibians. Forest Ecology and Management 29:39-57. 

Corn, PS., and J.C. Fogelman. 1984. Extinction of montane 
populations of the northern leopard frog (Rana pipiens) 
in Colorado. Journal of Herpetology 18:147-152. 

Dodd, C.K., Jr. 1991. The status of the Red Hills salaman- 
der Phaeognathus hubrichti, Alabama. USA, 1976-1988. 
Biological Conservation 55:57-75. 

Dunson, W.A., R.L. Wyman, and E.S. Corbett. 1992. A 
symposium on amphibian declines and habitat acidifica- 
tion. Journal of Herpetology 16:349-352. 

Freda. J. 1986. The influence of acidic pond water on 
amphibians: a review. Water, Air, and Soil Pollution 
30:439-450. 

Hayes, M.P.. and M.R. Jennings. 1986. Decline of ranid 
frog species in western North America: are bullfrogs 
{Rana catesbeiana) responsible? Journal of Herpetology 
20:490-509. 

Hine, R.L., B.L. Les, and B.F Hellmich. 1981. Leopard 
frog populations and mortality in Wisconsin. 1974-76. 
Wisconsin Department of Natural Resources Tech. Bull. 
122:1-39. 

Pechmann, J.H.K.. D.E. Scott, R.D. Semlitsch. J. P. 
Caldwell. L.J. Vitt, and J.W. Gibbons. 1991. Declining 
amphibian populations: the problem of separating human 
impacts from natural fluctuations. Science 253:892-895. 

Pechmann, J.H.K.. and H.M. Wilbur. 1994. Putting declin- 
ing amphibian populations in perspective: natural fluctu- 
ations and human impacts. Herpetologica 50:65-84. 

Petranka. J.W.. M.E. Eldridge. and K.E. Haley. 1993. 
Effects of timber harvesting on southern Appalachian 
salamanders. Conservation Biology 7:363-370. 

Pounds. J. A., and M.L. Crump. 1994. Amphibian declines 
and climate disturbance: the case of the golden toad and 
harlequin frog. Conservation Biology 8:72-85. 

Richards, S.J.. K.R. McDonald, and R.A. Alford. 1993. 
Declines in populations of Australia's endemic tropical 
rainforest frogs. Pacific Conservation Biology 1:66-77. 



Our Living Resources — Reptiles and Amphibians 



127 



The American alligator (Alligator mississip- 
piensis) is an integral component of wetland 
ecosystems in Florida. Alligators also provide 
aesthetic, educational, recreational, and eco- 
nomic benefits to humans. Because of the com- 
mercial value of alligator hides for making 
high-quality leather products, alligator hunting 
was a major economic and recreational pursuit 
of many Floridians from the mid-1800's to 
1970. The Florida alligator population varied 
considerably during the 1900s in response to 
fluctuating hunting pressure caused by unstable 
markets for luxury leather products. 

The declining abundance of alligators during 
the late 1950's and early 1960's led to the 1967 
classification of the Florida alligator population 
as endangered throughout its range. Federal and 
international regulations imposed during the 
1970's and 1980's helped control trade of alli- 
gator hides, and illegal hunting of alligators was 
checked. The Florida alligator population 
responded immediately to protection and was 
reclassified as threatened in 1 977 and as threat- 
ened because of its similarity in appearance to 
the American crocodile (Crocodylus acutus) in 
1985 (Neal 1985). 

Assessments of Florida's alligator popula- 
tion were based on sporadic surveys before 
1974 (Wood et al. 1985). The Florida Game and 
Fresh Water Fish Commission implemented 
annual night-light surveys that used spotlights 
to detect alligator eyeshine in 1 974 to provide a 
more objective basis for assessing population 
trends (Wood et al. 1985). Although all areas 
were not sampled every year, these data are the 
best available for alligator populations in 
Florida and are useful for estimating population 
trends (Woodward and Moore 1990). Because 
survey areas were not a random sample of all 
alligator habitat in Florida, trend results are 
applicable only to deepwater habitats and navi- 
gable wetlands. 




• 1974-82 
01983-92 



Design of Alligator Surveys, 
1974-92 

We conducted night-light counts (Woodward 
and Marion 1978) with high-intensity spotlights 
from boats on 54 areas throughout Florida (Fig. 
1) during 1974-92 (Woodward and Moore 
1990). The number of areas surveyed in any 
year ranged from 7 in 1974 to 43 in 1980. In 
1983 the number of areas surveyed was reduced 
to 22 to allow observers to conduct replicate 
counts on areas each year (Fig. 1). Eighteen of 
the 22 areas were subjected to alligator harvests 
of some type. 



American 
Alligators in 
Florida 

by 

Allan R. Woodward 
Florida Game and Fresh 
Water Fish Commission 

Clinton T. Moore 
U.S. Fish and Wildlife Service 




Fig. 1. Locations of survey areas for night-light counts of 
alligators in Florida, 1974-92. 



We analyzed observed densities of alligators 
per kilometer (0.62 mile) of shoreline to esti- 
mate trends for each area during the periods 
1974-92 and 1983-92. Size classes correspond- 
ed to the overall population, juveniles (0.3-1.2 
m [1-4 ft]), harvestable sizes (1.2 m or longer [4 
ft or longer]), and adults (1.8 m or longer [6 ft 
or longer]; hatchlings less than 0.3 m long [1 ft] 
were excluded from trend analysis). 

Count densities represent only alligators 
observed during the survey. Most (more than 
65%) alligators were submerged during surveys 
and not detected (Murphy 1977; Brandt 1989; 
Woodward and Linda 1993). Alligators in wet- 
lands adjacent to surveyed areas may have been 
undetected (Woodward and Linda 1993). 
Counts, however, do provide a relative measure 
of alligator abundance that is useful for estimat- 
ing population trends, provided that rates of 
detection do not vary annually. 

Status and Trends 

From 1974 to 1992, the density of alligators 
on surveyed wetlands increased an average 41% 



Alligators at dusk, Payne's Prairie 
State Preserve, Florida. 



128 



Reptiles and Amphibians — Our Living Resources 



or 1.9% annually. Average annual densities of 
harvestable alligators increased 2.7%, while 
average annual densities of adults increased 
2.5%. The 0.5% average annual increase in 
counts of juvenile alligators during 1974-92 
was not significant. These trends confirm that 
the Florida alligator population increased dur- 
ing the apparent recovery of the 1970's and 
1980's (Neal 1985). We observed cyclic pat- 
terns in abundance over time for all size classes 
(Fig. 2). Cyclic population levels may represent 
varying availability of counted alligators due to 
fluctuations in water level not fully accounted 
for in our analyses. They may also reflect pop- 
ulation changes brought about by periodic 
droughts or, to a lesser extent, severe winters. 




0.3m -1.2m (1-4 ft) 



S 4 





1 .8 m or longer (6 ft or longer) 



74 



76 



78 



82 



84 



% 



92 



Year 



Fig. 2. Annual indices (mean 
number of alligators detected per 
linear kilometer [0.62 mi] of sur- 
vey route) and smoothed trend 
estimates (Cleveland 1979) for 
three size classes of the statewide 
alligator population in Florida, 
1974-92. 



From 1983 to 1992, observed densities of 
adult alligators declined 3.2% per year, but we 
did not detect such trends in other size classes 
(Fig. 2). It is too early to draw conclusions con- 
cerning the influence of harvests on alligator 
populations since legal harvesting began in 
1987 because of the variable nature of night- 
light alligator counts and the uncertain effects 
of wariness. Relatively stable populations of 
juveniles and harvestable alligators indicate that 
hatchling recruitment (replenishment) is suffi- 
cient to replace alligators lost through harvest. 
Consequently, alligator harvests do not seem to 
have negatively affected the Florida alligator 
population as a whole. 

Historically, the Florida alligator population 
was threatened by habitat loss and excessive 
illegal hunting (Hines 1979), but recently envi- 
ronmental contamination has been associated 
with population declines. Wetland drainage and 
alteration during the 1900's destroyed alligator 
habitat and permanently reduced alligator pop- 



ulations in some wetlands, particularly in fresh- 
water marshes (Neal 1985). State legislation, 
most recently the Wetlands Protection Act of 
1984 (Florida Statutes 403.91), has significant- 
ly protected remaining wetlands, but alteration 
and loss of wetlands persist. Between the mid- 
1970's and mid- 1980's, 10,542 ha (26,030 
acres) of wetlands per year were lost to agricul- 
ture and other development (Frayer and Hefner 
1 99 1 ). Thus, habitat loss remains a threat to alli- 
gator populations. 

Illegal hunting is now negligible and has 
been replaced by regulated, managed harvests. 
Florida implemented a nuisance alligator con- 
trol program in 1978 in response to increasing 
problem alligators during the 1970's (Hines and 
Woodward 1980). Because the nuisance alliga- 
tor program targets individual alligators, the 
removal of these animals is unlikely to measur- 
ably affect alligator populations (Hines and 
Woodward 1980; Jennings et al. 1989). The 
state game commission introduced managed 
harvests of alligators and their eggs in 1987 to 
create conservation incentives by enhancing 
economic value of wild alligators (Wiley and 
Jennings 1990). Studies of the effects of harvest 
on alligator populations demonstrated that har- 
vests are sustainable at certain rates (Jennings et 
al. 1988; Woodward et al. 1992). Annual moni- 
toring and effective control of harvest rates 
ensure that populations will not suffer long- 
term depletion. 

More recently, environmental toxins have 
been implicated in the sharp decline of the alli- 
gator population on Lake Apopka, Florida's 
third-largest lake (Woodward et al. 1993; 
Guillette et al. 1994). Widespread pollution of 
wetlands by potentially toxic petrochemicals 
and metals may threaten the long-term viability 
of other alligator populations within Florida. 
For the present, the status of the Florida alliga- 
tor population is secure; however, continued 
habitat loss and toxic contamination will nega- 
tively affect alligator populations and may 
eventually compromise their conservation. 

References 

Brandt, L.A. 1989. The status and ecology of the American 
alligator (Alligator mississippiensis) in Par Pond. 
Savannah River Site. M.S. thesis. Florida International 
University, Fort Lauderdale. 89 pp. 

Cleveland, W.S. 1979. Robust locally weighted regression 
and smoothing scatterplots. Journal of the American 
Statistical Association 74:829-836. 

Frayer. W.E., and J.M. Hefner. 1991. Florida wetlands: sta- 
tus and trends, 1970 - s to 1980's. U. S. Fish and Wildlife 
Service, Atlanta. 33 pp. 

Guillette, L.J., Jr.. T.S. Gross. G.R. Masson, J.M. Matter. 
H.F Percival, and A.R. Woodward. 1994. Developmental 
abnormalities of the gonad and abnormal sex- hormone 
concentrations in juvenile alligators from contaminated 
and control lakes in Florida. Environmental Health 
Perspectives 102:680-688. 



Our Living Resources — Reptiles and Amphibians 



129 



Hines, T.C. 1979. The past and present status of the 
American alligator in Florida. Proceedings of the Annual 
Conference of the Southeastern Association of Fish and 
Wildlife Agencies 33:224-232. 

Hines, T.C, and A.R. Woodward. 1980. Nuisance alligator 
control in Florida. Wildlife Society Bull. 8:234-241. 

Jennings, M.L., H.F. Percival, and A.R. Woodward. 1988. 
Evaluation of alligator hatchling and egg removal from 
three Florida lakes. Proceedings of the Annual 
Conference of the Southeastern Association of Fish and 
Wildlife Agencies 42:283-294. 

Jennings, M.L., A.R. Woodward, and D.N. David. 1989. 
Florida's nuisance alligator control program. Pages 29- 
36 in S.R. Craven, ed. Proceedings of the Fourth Eastern 
Wildlife Damage Control Conference, Madison, WI. 

Murphy, T.M. 1977. Distribution, movement, and popula- 
tion dynamics of the American alligator in a thermally 
altered reservoir. M.S. thesis, University of Georgia, 
Athens. 64 pp. 

Neal, W. 1985. Endangered and threatened wildlife and 
plants; reclassification of the American alligator in 
Florida to threatened due to similarity of appearance. 
Federal Register 50(1 19):25,672-25,678. 

Wiley, E.N., and M.L. Jennings. 1990. An overview of alli- 
gator management in Florida. Pages 274-285 in 



Proceedings of the Tenth Working Meeting Crocodile 
Specialist Group. IUCN The World Conservation Union, 
Gland, Switzerland. 

Wood, J.M., A.R. Woodward, S.R. Humphrey, and T.C. 
Hines. 1985. Night counts as an index of American alli- 
gator population trends. Wildlife Society Bull. 13:262- 
273. 

Woodward, A.R., and S.B. Linda. 1993. Alligator popula- 
tion estimation. Final Report, Florida Game and Fresh 
Water Fish Commission, Tallahassee. 36 pp. 

Woodward, A.R., and W.R. Marion. 1978. An evaluation of 
night-light counts of alligators. Proceedings of the 
Annual Conference of the Southeastern Association of 
Fish and Wildlife Agencies 32:291-302. 

Woodward, A.R., and C.T Moore. 1990. Statewide alligator 
surveys. Final Report, Florida Game and Fresh Water 
Fish Commission, Tallahassee. 24 pp. 

Woodward, A.R., C.T. Moore, and M.F. Delany. 1992. 
Experimental alligator harvest. Final Report, Florida 
Game and Fresh Water Fish Commission, Tallahassee. 
118 pp. 

Woodward, A.R., H.F. Percival, M.L. Jennings, and C.T. 
Moore. 1993. Low clutch viability of American alligators 
on Lake Apopka. Florida Scientist 56:52-63. 



For further information: 

Allan R. Woodward 

Florida Game and Fresh Water 

Fish Commission 

4005 S. Main St. 

Gainesville, FL 32601 



The Coastal Plain of the southeastern United 
States contains a rich diversity of reptiles 
and amphibians (herpetofauna). Of the 290 
species native to the Southeast, 170 (74 amphib- 
ians, 96 reptiles) are found within the range of 
the remnant longleaf pine (Pinus palustris) 
ecosystem (Fig. 1). Many of these species are 
not found elsewhere, particularly those amphib- 
ians that require temporary ponds for reproduc- 
tion. Many Coastal Plain species are listed fed- 
erally or by states as endangered or threatened 
or are candidates for listing (Fig. 1). Examples 
include the flatwoods salamander (Ambystoma 
cingulatum), striped newt (Notophthalmus per- 
striatits), Carolina and dusky gopher frogs 
(Rana capito capito and R.c. sevosa), eastern 
indigo snake {Drymarchon corais couperi), 
gopher tortoise (Gopherus polyphemus), eastern 
diamondback rattlesnake (Crotalus adaman- 
teus), and Florida pine snake (Pituophis 
melanoleucus mugitus). 

Studies in the Southeast 

Information on the status and trends of the 
Coastal Plain herpetofauna comes from limited 
studies of selected species or populations, most- 
ly within the last decade. The only intensive 
long-term quantitative and community-based 
studies have been at the Savannah River Site on 
the upper Coastal Plain of South Carolina. Most 
other studies have been distributional surveys 
for species such as Red Hills salamanders 
{Phaeognathus hubrichti), gopher frogs, striped 
newts, flatwoods salamanders, gopher tortoises, 
and Florida scrub lizards (Sceloporus woodi). 
Few studies have reported detailed habitat 



requirements for suspected declining species 
throughout their range. Surveys generally range 
1-2 years in duration. Other trend information is 
derived from studies conducted by university 
scientists, private organizations, or state 
resource agencies. Concern for the future of the 
entire herpetofaunal community in the 
Southeast rests mostly on the well-documented 
loss of the old-growth longleaf pine ecosystem, 
although few community-based herpetofaunal 
surveys have been undertaken in this habitat. 

Status 

The fire-adapted longleaf pine community 
once stretched from southeastern Virginia to 
eastern Texas (Fig. 2). At present, less than 14% 
of the historical 282,283 km 2 (70 million acres) 
longleaf pine forest remains (Means and Grow 
1985; Noss 1989), and most of it is on private 
land. Less than 1% is old-growth forest. 
Conversion of longleaf pine forests for agricul- 
ture, timber plantations, and urban needs (Ware 
et al. 1993) is accelerating (Fig. 3) and probably 
threatens the continued existence of many 
amphibian and reptile species, particularly in 
southern Georgia and Florida. For example, 
longleaf pine forests in Florida declined from 
30,756 km 2 (7.6 million acres) in 1936 to only 
3,845 km 2 (0.95 million acres) in 1989, an 88% 
decrease (Cerulean 1991). In southeastern 
Georgia the longleaf pine forest declined 36% 
(to 931 km 2 [230,000 acres]) between 1981 and 
1988 (Johnson 1988). Most of this conversion 
has been from second- or third-growth longleaf 
pine stands to slash or loblolly pine plantation 
forestry. 



Reptiles and 
Amphibians in 
the 

Endangered 
Longleaf Pine 
Ecosystem 

by 

C. Kenneth Dodd, Jr. 

National Biological Service 



130 



Reptiles and Amphibians — Our Living Resources 



| Reptiles & amphibians in range 
of Longleaf pine 

EfiVR/D 




Fig. 1. Reptiles and amphibians 
within the southeastern Coastal 
Plain. Green bars = total number; 
Gold bars = number of species in 
need of conservation and manage- 
ment. E = endangered, T = threat- 
ened, R = rare, D = declining. 



Fig. 2. Historical distribution of 
the longleaf pine ecosystem in the 
southeastern Coastal Plain. Chart 
shows the present total number of 
species of amphibians and reptiles 
in various southeastern states. 



The effects of the loss of the longleaf pine 
ecosystem on the herpetofaunal community 
have never been assessed directly, but several 
species are known to have been affected. For 
example, the number of gopher tortoises, a key 
species within the longleaf pine ecosystem, has 
declined by an estimated 80% during the last 
100 years (Auffenberg and Franz 1982). More 
than 300 invertebrates and 65 vertebrates use 
gopher tortoise burrows (Jackson and Milstrey 
1989; Fig. 4), so an 80% reduction in gopher 
tortoises could represent a substantial reduction 
in the biodiversity of the longleaf pine ecosys- 
tem. 

Amphibians that breed in temporary ponds 
have been particularly affected both because of 
direct habitat destruction and the slower loss of 
wetland breeding sites by ditching. Breeding, 
foraging, and overwintering sites are also 
affected by certain types of forest plantation site 
preparation. Only five populations of striped 
newts remain in Georgia (Dodd 1993; L. 
LaClaire, USFWS, personal communication); 
the flatwoods salamander has disappeared from 
the eastern section of its range; gopher frogs are 
nearly extirpated in North Carolina, Alabama, 
and Mississippi; and dusky salamanders 
{Desmognathus spp.) appear to havedeclined or 
disappeared in coastal South Carolina and 
peninsular Florida. 

On the other hand, the long-term communi- 
ty studies at the Savanna River Site, where the 
destructive effects of plantation forestry are not 
prevalent, do not reveal declining trends, 
although some amphibian populations there 
fluctuate widely from one year to the next in 



80 



60 



40 



20 







mr rrp 



VA NC SC GA FL AL MS LA TX 




Longleaf pine 
Urban areas 
Human population 



15 

13 




Fig. 3. Trend in loss of longleaf pine forest in relation to 
urban development and increases in human population in 
Florida, 1930-90 (Cerulean 1991; used with permission 
from The Nature Conservancy). 

both numbers and reproductive output 
(Pechmann et al. 1991). A 5-year study on a 
north Florida biological preserve disclosed 
declining amphibian numbers, but the study 
coincided with a severe regional drought (Dodd 
1992). In west-central Florida, amphibian com- 
munities have changed composition because of 




Fig. 4. The distribution of the gopher tortoise (Gopherus 
polyphemus) in the southeastern United States. The chart 
shows the number of species of various taxa known to use 
its burrow and the number of plant taxa described from the 
longleaf pine-wiregrass ecosystem. 



Our Living Resources — Reptiles and Amphibians 



131 



urbanization (Delis 1993), but the long-term 
effects of the change are unknown. The overall 
status of the Red Hills salamander (federal 
threatened list) remained the same from 1976 to 
1 988 (Dodd 1 99 1 ). although habitat loss contin- 
ued from plantation forestry. Virtually no data 
exist for terrestrial reptile populations or com- 
munities except for the gopher tortoise. 
Anecdotal information for all terrestrial reptiles 
suggests population declines, particularly in 
areas affected by imported red fire ants 
{Solenopsis invicta). 

Local centers of amphibian and reptile diver- 
sity need to be identified within the remaining 
longleaf pine community. Surveys, basic life- 
history studies of sensitive species, and long- 
term monitoring of amphibian and reptile popu- 
lations need to be initiated. Many species that 
are restricted to wetland and upland habitats 
appear to be declining, but precise baseline data 
are lacking. Factors impeding the identification 
of population trends include the longevity of 
many species, the effects of periodic natural 
events such as drought, and what appear to be 
random population fluctuations. At the same 
time, when the known extent of habitat loss is 
coupled with declining trends elsewhere 
(Blaustein and Wake 1990; Wyman 1990) that 
result from unknown or hypothesized causes 
(UVB light, acidity, heavy metals, estrogen- 
mimicking compounds, roads, habitat fragmen- 
tation), the study and monitoring of amphibian 
and reptile populations in remnant southeastern 
longleaf pine forests will become especially 
imperative. 

References 

Auffenberg, W., and R. Franz. 1982. The status and distrib- 
ution of the gopher tortoise (Gopherus polyphemus). 



Pages 95-126 in R.B. Bury, ed. North American tortois- 
es: conservation and ecology. U.S. Fish and Wildlife 

Service Res. Rep. 12. 
Blaustein, A.R., and D.B. Wake. 1990. Declining amphibian 

populations: a global phenomenon? Trends in Ecology 

and Evolution 5:203-204. 
Cerulean, S.I. 1991. The preservation 2000 report. Florida's 

natural areas — what have we got to lose? The Nature 

Conservancy, Winter Park, FL. 74 pp. 
Delis, PR. 1993. Effects of urbanization on the community 

of anurans of a pine flatwood habitat in west central 

Florida. M.S. thesis, University of South Florida, 

Tampa. 47 pp. 
Dodd, C.K., Jr. 1991. The status of the Red Hills salaman- 
der Phaeognathus hubrichti, Alabama, USA, 1976-1988. 

Biological Conservation 55:57-75. 
Dodd, C.K., Jr. 1992. Biological diversity of a temporary 

pond herpetofauna in north Florida sandhills. 

Biodiversity and Conservation 1:125-142. 
Dodd, C.K., Jr. 1993. Distribution of striped newts 

(Notophthalmus perstriatus) in Georgia. Report to U.S. 

Fish and Wildlife Service, Jacksonville. FL. 52 pp. 
Jackson. D.R., and E.G. Milstrey. 1989. The fauna of 

gopher tortoise burrows. Florida Nongame Wildlife 

Program Tech. Rep. 5:86-98. 
Johnson, T.G. 1988. Forest statistics for southeast Georgia, 

1988. USDA Forest Service Resour. Bull. SE-104. 53 

pp. 
Means. D.B., and G. Grow. 1985. The endangered longleaf 

pine community. ENFO (Florida Conservation 

Foundation) Sept: 1-12. 
Noss, R.F. 1989. Longleaf pine and wiregrass: keystone 

components of an endangered ecosystem. Natural Areas 

Journal 9:211-213. 
Pechmann, J.H.K., D.E. Scott, R.D. Semlitsch, J. P. 

Caldwell, L.J. Vitt, and J.W. Gibbons. 1991. Declining 

amphibian populations: the problem of separating human 

impacts from natural fluctuations. Science 253:892-895. 
Ware, S.. C. Frost, and P.D. Doerr. 1993. Southern mixed 

hardwood forest: the former longleaf pine forest. Pages 

447-493 in W.H. Martin, S.G. Boyce, and A.C. 

Echternacht, eds. Biodiversity of the southeastern United 

States. Lowland terrestrial communities. John Wiley and 

Sons, New York. 
Wyman, R.L. 1990. What's happening to the amphibians? 

Conservation Biology 4:350-352. 



For further information: 

C. Kenneth Dodd, Jr. 

National Biological Service 

Southeastern Biological Science 

Center 

7920 N.W. 71 st St. 

Gainesville, FL 32653 



Many recent declines and extinctions of 
native amphibians have occurred in cer- 
tain parts of the world (Wake 1991; Wake and 
Morowitz 1991). All species of native true frogs 
have declined in the western United States over 
the past decade (Hayes and Jennings 1986). 
Most of these native amphibian declines can be 
directly attributed to habitat loss or modifica- 
tion, which is often exacerbated by natural 
events such as droughts or floods (Wake 1991). 
A growing body of research, however, indicates 
that certain native frogs are particularly suscep- 
tible to population declines and extinctions in 
habitats that are relatively unmodified by 
humans (e.g., wilderness areas and national 
parks in California; Bradford 1991; Fellers and 
Drost 1993; Kagarise Sherman and Morton 
1993). To understand these declines, we must 



document the current distribution of these 
species over their entire historical range to learn 
where they have disappeared. 

In 1988 the California Department of Fish 
and Game commissioned the California 
Academy of Sciences to conduct a 6-year study 
on the status of the state's amphibians and rep- 
tiles not currently protected by the Endangered 
Species Act. The study's purpose was to deter- 
mine amphibians and reptiles most vulnerable 
to extinction and provide suggestions for future 
research, management, and protection by state, 
federal, and local agencies (Jennings and Hayes 
1993). This article describes the distribution and 
status of all native true frogs in California as 
determined by the California Fish and Game 
study. 



Native Ranid 
Frogs in 
California 



by 

Mark R. Jennings 
National Biological Service 



132 



Reptiles and Amphibians — Our Living Resources 



Status 

All species studied have suffered declines in 
distribution and abundance, largely because of 
habitat loss or modification from farming, graz- 
ing, logging, urban development, suppression 
of brush fires, and flood-control or water-devel- 
opment projects. The species have also been 
affected by the widespread introduction of ver- 
tebrate and invertebrate aquatic predators. 

Northern Red-legged Frog (Rana aurora 
aurora) 

This frog, restricted to lower elevations (300 
m [984 ft]) of the north coast region of 
California (Fig. 1), has disappeared from about 
15% of its historical range in California. It is 
not in danger of extinction in the state. 




Fig. 1. Historical and current distribution of the northern red-legged frog, California red-legged 
frog, and Cascades frog in California based on 2,068 museum records and 302 records from other 
sources. Dots indicate locality records based on verified museum specimens. Squares indicate 
locality records based on verified sightings (e.g., field notes, photographs, published papers). Red 
dots and green squares denote localities where native frogs are extant. Gold dots and blue squares 
indicate where native frogs are presumed extinct. Figure modified from Jennings and Haves 
(1993). 



California Red-legged Frog {R.a. draytonii) 

This frog was originally found over most of 
California below 1,524 m (500 ft) and west of 
the deserts and the Sierra Nevada crest (Fig. 1 ). 
Although the California red-legged frog has 
now disappeared from about 75% of its histori- 
cal range in the state, around the turn of the cen- 
tury it was abundant enough to support an 
important commercial fishery in the San 
Francisco fish markets (Jennings and Hayes 
1984). California red-legged frogs have almost 
completely disappeared from the Central Valley 
and southern California since 1970 and are cur- 
rently proposed for listing as endangered by the 
U.S. Fish and Wildlife Service (Federal 
Register 1994). 

Cascades Frog (R. cascadae) 

The Cascades frog was originally found in 
northern California above 230 m (755 ft; Fig. 
1), where it was historically very abundant. 
Since the mid-1970's, the species extensively 
declined, disappearing from about 50% of its 
range in the state. No habitat loss hypothesis 
adequately explains why this frog survived with 
current land-use practices for over 50 years 
before its decline. It is still abundant in 
California only in the northern third of its range 
on lands under federal ownership. 

Foothill Yellow-legged Frog (R. boylii) 

This frog was originally found over most of 
California below 1 ,829 m (6,000 ft), west of the 
deserts and the Sierra-Cascade crest (Fig. 2). In 
many locations before 1970, populations con- 
tained hundreds of individuals (Zweifel 1955), 
but the frog has now completely disappeared 
from southern California and from about 45% 
of its historical range over the entire state. Most 
populations were apparently healthy until the 
mid-1970's, when a population crash occurred 
in southern California and the Sierra Nevada 
foothills after several years of severe floods and 
drought, which may have been responsible for 
the declines, although it is not certain. Because 
this species was an important component of the 
food web in many streamside ecosystems, its 
loss has probably negatively affected several 
organisms, such as garter snakes (Thamnophis 
spp.), which historically relied upon it as a 
major food source. 

Spotted Frog (R. pretiosa) 

The spotted frog was historically recorded 
only from scattered localities in the extreme 
northeastern part of California below 1,372 m 
(4,500 ft), where it was apparently restricted to 
large marshy areas filled by warmwater (more 
than 20°C [68°F]) springs (Fig. 2). It has now 



Our Living Resources — Reptiles and Amphibians 



133 



disappeared from about 99% of its range, and is 
only known from one location in the state. It 
appears to be on the verge of extinction in 
California. 

Yavapai Leopard Frog (R. yavapaiensis) 

This frog was originally found along the 
Colorado River and in the Coachella Valley of 
southeastern California (Fig. 2). It has not been 
seen in the state since the mid-1960's and now 
seems to be extinct at all sites examined. This 
leopard frog has been replaced in California by 
the introduced bullfrog (R. catesbeiana) and the 
Rio Grande leopard frog (R. berlandieri), which 
are able to thrive in human-modified reservoirs 
and canals in the Yavapai leopard frog's original 
range (Jennings and Hayes 1994). 

Mountain Yellow-legged Frog (R. muscosa) 

This species was historically abundant in the 
Sierra Nevada at elevations largely above 1,829 
m (6,000 ft), and also in the San Gabriel, San 
Bernardino, and San Jacinto mountains of 
southern California above 369 m (1,210 ft; Fig. 
3). The mountain yellow-legged frog has disap- 
peared from about 50% of its historical range in 
the Sierra Nevada and about 99% of its histori- 
cal range in southern California. Some 
researchers believe that the widespread intro- 
duction of non-native trout into high-elevation 
lakes is the major reason for the decline of this 
species in the Sierra Nevada (Bradford 1989; 
Bradford et al. 1993). The species, however, 
experienced massive die-offs in many parts of 
its range during the 1970's (Bradford 1991) 
after several years of severe floods and drought, 
and continues to decline in relatively pristine 
areas such as wilderness areas and national 
parks. 

Such observations indicate that present land- 
management practices of setting aside large 
tracts of land for the "protection of biodiversi- 
ty" may not be adequate for ensuring the con- 
tinued survival of this species. Already, the loss 
of this frog over large areas has negatively 
affected organisms such as the western terrestri- 
al garter snake (Thamnophis elegans), which 
relied upon it as a major food source (Jennings 
et al. 1992). To keep these populations from 
extinction, resource managers may need to ini- 
tiate active management efforts for mountain 
yellow-legged frogs (such as fish eradication 
programs in selected high-elevation lakes, fenc- 
ing of riparian zones to exclude livestock graz- 
ing, and relocating hiking trails and camp- 
grounds away from sensitive riparian habitats). 

Northern Leopard Frog (R. pipiens) 

This frog was historically recorded from 
scattered localities below 1,981 m (6,500 ft) in 



^mM 




Northern red-legged frog (Rana aurora aurora). 




Fig. 2. Historical and current distribution of the foothill yellow-legged frog, spotted frog, and 
Yavapai leopard frog in California based on 3,316 museum records and 171 records from other 
sources. Dots indicate locality records based on verified museum specimens. Squares indicate 
locality records based on verified sightings (e.g., field notes, photographs, published papers). Red 
dots and green squares denote localities where native frogs are extant. Gold dots and blue squares 
indicate where native frogs are presumed extinct. Figure modified from Jennings and Hayes 
(1993). 



134 



Reptiles and Amphibians — Our Living Resources 




Fig. 3. Historical and current distribution of the mountain yellow-legged frog, and presumed 
native populations of the northern leopard frog in California based on 2.565 museum records and 
673 records from other sources. Dots indicate locality records based on verified museum speci- 
mens. Squares indicate locality records based on verified sightings (e.g.. field notes, photographs, 
published papers). Red dots and green squares denote localities where native frogs are extant. 
Gold dots and blue squares indicate where native frogs are presumed extinct. Figure modified 
from Jennings and Hayes (1993). 



the eastern part of California (Fig. 3). Some 
populations were introduced into the state with- 
in the past 100 years (Jennings and Hayes 
1993), most around the turn of the century 
(Storer 1925). This species has disappeared 
from about 95% of its range in California and is 
now found only in one national wildlife refuge 
near the Oregon border. Most localities where 
this frog was historically found have not 
changed appreciatively during the past 50 years, 
so the reasons for the species' decline and dis- 
appearance remain a mystery. 



For further information: 

Mark R. Jennings 
National Biological Service 

Alaska Science Center 

Piedras Blancas Field Station 

PO Box 70 

San Simeon, CA 93452 



References 

Bradford. D.F. 1989. Allotopic distribution of native frogs 
and introduced fishes in the high Sierra Nevada lakes of 
California: implication of the negative effects of fish 
introductions. Copeia 1989(3):775-778. 

Bradford, D.F. 1991. Mass mortality and extinction in a 
high elevation population of Rana muscosa. Journal of 
Herpetology 25(2): 174- 177. 

Bradford, D.F., D.M. Graber. and F. Tabatabai. 1993. 
Isolation of remaining populations of the native frog. 
Rana muscosa, by introduced fishes in Sequoia and 
Kings Canyon National Parks. California. Conservation 
Biology 7(4):882-888. 

Federal Register. 1994. Endangered and threatened wildlife 
and plants; proposed endangered status for the California 
red-legged frog. Federal Register 59(22):4888-4895. 

Fellers, G.M.. and C.A. Drost. 1993. Disappearance of the 
Cascades frog Rana cascadae at the southern end of its 
range. California. USA. Biological Conservation 
65(2):177-181. 

Hayes, M.P., and M.R. Jennings. 1986. Decline of ranid 
frog species in western North America: are bullfrogs 
(Rana catesbeiana) responsible? Journal of Herpetology 
20(4):490-509. 

Jennings, M.R., and M.P. Hayes. 1984. Pre-1900 overhar- 
vest of the California red-legged frog (Rana aurora dray- 
tonii): the inducement for bullfrog (Rana catesbeiana) 
introduction. Herpetologica 41(1 ):94-103. 

Jennings, M.R., and M.P. Hayes. 1993. Amphibian and rep- 
tile species of special concern in California. Final report 
submitted to the California Department of Fish and 
Game. Inland Fisheries Division. Rancho Cordova, under 
Contract (8023). 336 pp. 

Jennings, M.R., and M.P. Hayes. 1994. Decline of native 
ranid frogs in the desert southwest. In PR. Brown and 
J.W. Wright, eds. Proceedings of the Conference on the 
Herpetology of the North American Deserts. 
Southwestern Herpetologists Society. Spec. Publ. 5. In 
press. 

Jennings. W.B.. D.F. Bradford, and D.F. Johnson. 1992. 
Dependence of the garter snake Thamnophis elegans on 
amphibians in the Sierra Nevada of California. Journal of 
Herpetology 26(4):503-505. 

Kagarise Sherman. C. and M.L. Morton. 1993. Population 
declines of Yosemite toads in the eastern Sierra Nevada 
of California. Journal of Herpetology 27(2): 186-198. 

Storer. T.I. 1925. A synopsis of the amphibia of California. 
University of California Publications in Zoology 27:1- 
343. 

Wake, D.B. 1991. Declining amphibian populations. 
Science 253(5022):860. 

Wake. D.B.. and H.J. Morowitz. 1991. Declining amphibian 
populations — a global phenomenon? Findings and rec- 
ommendations. Alytes 9(1 ):33-42. 

Zweifel, R.G. 1955. Ecology, distribution, and systematica 
of frogs of the Rana boylei group. University of 
California Publications in Zoology 54(4):207-292. 



Our Living Resources — Reptiles and Amphibians 



135 



The desert tortoise {Gopherus agassizii) is a 
widespread species of the southwestern 
United States and Mexico. Within the United 
States, desert tortoises live in the Mojave, 
Colorado, and Sonoran deserts of southeastern 
California, southern Nevada, southwestern 
Utah, and western Arizona (Fig. 1). A substan- 
tial portion of the habitat is on lands adminis- 
tered by the U.S. Department of the Interior. 

The U.S. government treats the desert tor- 
toise as an indicator or umbrella species to mea- 
sure the health and well-being of the ecosys- 
tems it inhabits. The tortoise functions well as 
an indicator because it is long-lived, takes 12-20 
years to reach reproductive maturity, and is sen- 
sitive to changes in the environment. In 1990 
the U.S. Fish and Wildlife Service listed the 
species as threatened in the northern and west- 
ern parts of its geographic range (Fig. 1) 
because of widespread population declines and 
overall habitat loss, deterioration, and fragmen- 
tation. 

Because some populations exhibit signifi- 
cant genetic, morphologic {see glossary), and 
behavioral differences, the Desert Tortoise 
Recovery Team identified six distinctive popu- 
lation segments (Fig. 1) for critical habitat pro- 
tection and long-term conservation within the 
Mojave and Colorado deserts (e.g., Lamb et al. 
1989; USFWS 1994). The population segments 
are representative of distinctive climatic, floris- 
tic, and geographic regions. 

Surveys 

The primary sources of information on sta- 
tus and trends of desert tortoise populations are 
from study plots established by the U.S. Bureau 
of Land Management and state fish and game 
agencies. More than 30 permanent study plots, 
each of which is 2.6 km 2 or larger (1 mi 2 or 
more), are surveyed at intervals ranging from 2 
to 10 years. Study plots provide data on popula- 
tion characteristics, including density, size-age 
class structure, sex ratios and numbers of breed- 
ing females, recruitment of juveniles into the 
adult population, causes of death, and mortality 
rates (Berry 1990). Researchers use mark- 
recapture techniques to conduct 60-day surveys 
in spring for live and dead tortoises. 

Trends for habitat condition on study plots 
are measured by using quantitative data on 
native and exotic annual and perennial vegeta- 
tion (Berry 1990). Associated data on past and 
recent human activities or influences include 
numbers of visitors per season; density of dirt 
roads, trails, and vehicle tracks; levels and types 
of livestock grazing; and acreage disturbed by 
mining and mineral development and utility 
corridors. 



The data base for the six population seg- 
ments varies considerably; some segments con- 
tain several plots that have been sampled for 1 1- 
17 years, whereas others have few plots that 
have been sampled only 1 or 2 years (Berry 
1990; USFWS 1994). 

Trends 

Condition and trends in tortoise populations 
vary within and between population segments. 
One measure of population condition is change 
in density. Examples of changes in density for 
nine study plots in California and Nevada are 
shown in Fig. 2 (Berry 1990; D.B. 
Hardenbrook, Nevada Division of Wildlife, and 
S. Slone, Bureau of Land Management, person- 
al communication). The greatest declines in 



Desert 
Tortoises in 
the Mojave 
and Colorado 
Deserts 



by 

Kristin H. Berry 

Philip Medica 

National Biological Service 




densities, for all size classes and for breeding 
females (up to 90%), occurred in the western 
Mojave segment between the 1970's and 
1990's. Similar declines (30%-60%) also 
occurred in the eastern Colorado Desert seg- 
ment between 1979 and 1992, with the greatest 
declines registered at the Chuckwalla Bench 
plot (Fig. 2). Moderate declines of 20%-25% 
were reported from some sites in the eastern 
Mojave Desert segment (Piute Valley and 
Goffs). The northeastern Mojave also exhibited 
declines on some plots (e.g., Ivanpah Valley and 
Gold Butte). In contrast, the northern Colorado 
Desert population segment showed indications 
of growth in the breeding adults at one plot 
(Ward Valley), and the upper Virgin River seg- 
ment appears stable (USFWS 1994). 



Fig. 1. U.S. range of the desert 
tortoise {Gopherus agassizii). The 
six population segments for desert 
tortoises federally listed as threat- 
ened occur in parts of the Mojave 
and Colorado deserts that lie north 
and west of the Colorado River. 




Desert tortoise (Gopherus agas- 
sizii). 



136 



Reptiles and Amphibians — Our Living Resources 



300- 



®lvanpah Valley: ($) Desert Tortoise Natural Area: fg\ Chuckwalla Bench: 

northeastern Mojave Desert, ^ western Mojave Desert, CA ^ eastern Colorado Desert, 



CA (1979-90) 



(1979-92) 



©Ward Valley: 
northern Colorado Desert, 
CA (1980-91) 



©Goffs: 
eastern Mojave Desert, CA 
(1980, 1990) 




250 



©Piute Valley: 
eastern Mojave Desert, NV 
(1983, 1989) 



fp\ Sheep Mountain: 
vis eastern Mojave Desert, NV 
(1984, 1992) 



©Gold Butte: 
northeastern Mojave Desert, 
NV (1986, 1990) 



©Trout Canyon 
eastern Moj; 
(1987,1992 



eastern Mojave Desert, NV 



all sizes j 



95% 

confidence 

interval 



— 200- 



Midpoint 
for density 
estimates 



\l 




95% 

confidence 

interval 



Year 



90 



80 



Year 



90 



Year 



90 



80 Year 



90 



Fig. 2. Examples of changes in 
desert tortoise population densities 
at nine study sites in California 
and Nevada. The midpoint for 
density estimates of all sizes of 
tortoises (orange line) is shown by 
a dot on a bar representing the 
95% confidence interval (CI); the 
midpoint for density estimates for 
adult tortoises only (red lines) is 
depicted by a square on a bar rep- 
resenting the 95% CI. Causes of 
declines vary by site. 



Causes of population declines differed 
somewhat within and between population seg- 
ments, but were primarily related to human 
activities. Higher than normal losses or mortal- 
ity rates were attributed to many causes, such as 
illegal collecting, vandalism, upper respiratory 
tract disease or shell disease, predation by com- 
mon ravens, crushing by vehicles both on and 
off roads, and trampling by livestock (BLM 
1988; USFWS 1994). For example, 14.6%- 
28.9% of desert tortoise carcasses collected 
from western Mojave plots in the 1970's and 
early 1980's showed signs of gunshots (tortois- 
es were shot while still alive), but only 0%- 
3.1% of carcasses from the less-visited eastern 
Mojave and northern Colorado deserts showed 
such signs (Berry 1986). Deaths from vehicles 
on paved roads were also highest in the western 
Mojave, where densities of dirt roads and vehi- 
cle trails are higher than elsewhere. 

Of particular concern is the recent appear- 
ance of a highly infectious and usually fatal 
upper respiratory tract disease caused by the 
bacterium Mycoplasma agassizii. The disease, 
apparently introduced through the release of 
captive tortoises (Jacobson 1993), has caused 



the deaths of thousands of wild tortoises in the 
Mojave Desert during the last few years (K.H. 
Berry, unpublished data). 

Fragmented and deteriorated habitats also 
affect population vitality. Populations in areas 
with high levels of exotic annual plants are 
declining at substantially higher rates than those 
in less disturbed areas. 

In summary, tortoise populations occurring 
in relatively undisturbed and remote areas with 
little vehicular access and low human visitation 
generally were stable, or exhibited lower rates 
of decline than tortoise populations in areas 
with high levels of disturbance, high vehicular 
access, and high human visitation. 

References 

Berry, K.H. 1986. Incidence of gunshot deaths in desert tor- 
toises in California. Wildlife Society Bull. 14:127-132. 

Berry, K.H. 1990. The status of the desert tortoise in 
California in 1989 (with amendments to include 1990- 
1992 data sets). Draft report from U.S. Bureau of Land 
Management to U.S. Fish and Wildlife Service. Region 
i. Portland. OR. 

BLM. 1988. Desert tortoise habitat management on the pub- 
lic lands: a rangewide plan. U.S. Bureau of Land 
Management. Washington. DC. 23 pp. 



Our Living Resources — Reptiles and Amphibians 



137 



Jacobson, E.R. 1993. Implications of infectious diseases for 
captive propagation and introduction programs of threat- 
ened/endangered reptiles. Journal of Zoo and Wildlife 
Medicine 24(3):245-255. 

Lamb, T., J. Avise, and J.W. Gibbons. 1989. Phylogeo- 
graphic patterns in mitochondrial DNA of the desert tor- 
toise (Xerobates agassizi) and evolutionary relationships 



among the North American gopher tortoises. Evolution 
43(l):76-87. 
USFWS. 1994. Desert Tortoise (Mojave Population) 
Recovery Plan. U.S. Fish and Wildlife Service, Portland, 
OR. 77 pp. + appendices. 



For further information: 

Kristin H. Berry 

National Biological Service 

Riverside Field Station 

6221 Box Springs Blvd. 

Riverside, CA 92507 



Fringe-toed lizards {Uma spp.) inhabit many 
of the scattered windblown sand deposits of 
southeastern California, southwestern Arizona, 
and northwestern Mexico. These lizards have 
several specialized adaptations: elongated 
scales on their hind feet ("fringes") for added 
traction in loose sand, a shovel-shaped head and 
a lower jaw adapted to aid diving into and mov- 
ing short distances beneath the sand, elongated 
scales covering their ears to keep sand out, and 
unique morphology (form or structure) of inter- 
nal nostrils that allows them to breathe below 
the sand without inhaling sand particles. 

While these adaptations enable fringe-toed 
lizards to successfully occupy sand dune habi- 
tats, the same characteristics have restricted 
them to isolated sand "islands." Three fringe- 
toed lizard species live in the United States: the 
Mojave (U. scopaha), the Colorado Desert (£/. 
notata), and the Coachella Valley (U. inornata). 
Of the three, the Coachella Valley fringe-toed 
lizard has the most restricted range and has been 
most affected by human activities. In 1980 this 
lizard was listed as a threatened species by the 
federal government. 

In 1986 the Coachella Valley Preserve sys- 
tem was established to protect habitat for the 
Coachella Valley fringe-toed lizard. This action 
set several precedents: it was the first Habitat 
Conservation Plan established under the 
revised (1982) Endangered Species Act and the 
newly adopted Section 10 of the act, it estab- 
lished perhaps the only protected area in the 
world set aside for a lizard, and its design was 
based on a model of sand dune ecosystem 
processes, the sole habitat for this lizard. Three 
disjunct sites in California, each with a discrete 
source of windblown sand, were set aside to 
protect fringe-toed lizard populations: 
Thousand Palms, Willow Hole, and Whitewater 
River. Collectively, the preserves protect about 
2% of the lizards' original range. 

Eight years after the establishment of the 
preserve system, few Coachella Valley fringe- 
toed lizards exist outside the boundaries of the 
three protected sites. Barrows (author, unpub- 
lished data) recently identified scattered pockets 
of windblown sand occupied by fringe-toed 
lizards in the hills along the northern fringe of 
the valley, but only at low densities. Fringe-toed 
lizard populations within the protected sites 
have been monitored yearly since 1986. During 



this period, California experienced one of its 
most severe droughts, which ended in spring 
1991. Numbers of fringe-toed lizards within the 
Thousand Palms and Willow Hole sites 
declined during the drought, but rebounded 
after 1991 (Fig. 1). By 1993, after three wet 
springs, lizard numbers had increased substan- 
tially. 

Lizards at the Whitewater River site were 
intensively monitored since 1985 by using 
mark-recapture methods to count the population 
on a 2.25-ha (5.56-acre) plot. In 1986 this site 




87 



89 
Year 



had the highest population density of the three 
protected sites. As with the other two sites, the 
Whitewater River population declined through- 
out the drought, but only increased slightly after 
the drought broke in 1991 (Fig. 2). 
Compounding the drought effect, much of the 
fine sand preferred by fringe-toed lizards was 
blown off the site during the dry years. This 
condition was unique to the Whitewater River 




Coachella 
Valley Fringe- 
toed Lizards 

by 

Cameron Barrows 

The Nature Conservancy 

Allan Muth 

Mark Fisher 

University of California, Boyd 

Deep Canyon Desert 

Research Center 

Jeffrey Lovich 
National Biological Service 



Fig. 1. The mean number of 
lizards per transect at the 
Thousand Palms and Willow Hole 
sites, 1986-93. Data were pooled 
from five 10 x 1,000 m (32.8 x 
3,281 ft) transects. All transects 
were sampled six times each year, 
and all sampling was conducted 
within a 6-week span in the late 
spring of each year. 



Coachella Valley fringe-toed lizard 
(Uma inornata). 



138 



Reptiles and Amphibians — Our Living Resources 



Fig. 2. The known population size 
of a Coachella Valley fringe-toed 
lizard population on a 2.25-ha 
(5.56-acre) study plot on the 
Whitewater River preserve. 



For further information: 

Cameron Barrows 

The Nature Conservancy 

53277 Avenida Diaz 

La Quinta, CA 92253 




Year 



site; the other two protected sites have much 
deeper sand deposits and are less susceptible to 
wind erosion. New windblown sand was 
deposited on the Whitewater River site in 1993 
after a period of high rainfall. The population 
appears to be increasing in response to these 
favorable conditions. 



The decline in fringe-toed lizards during the 
monitoring period appears to be the result of 
responses to natural fluctuations in habitat. The 
dynamic nature of sand dune systems, coupled 
with the lizards' apparent sensitivity to drought, 
underlines the importance of preserve design. 
Appropriate designs anticipate the effect of nat- 
ural habitat fluctuation. 

The ecological model that governed the 
design of the Coachella Valley Preserve system 
was reevaluated in 1993 with one disturbing 
result. A primary sand source was identified that 
supplies the sand dunes at the Thousand Palms 
site, but was not emphasized sufficiently in the 
original model and design. Fortunately, the sand 
source and its path to the existing preserve have 
not been affected severely by human develop- 
ment at this time, so options for correcting the 
design's shortcomings are still available. The 
fringe-toed lizard population sustained by this 
sand source has been the largest of the three 
sites for the past few years. Monitoring the 
lizards without investigating ecosystem 
processes would not have identified the design 
error until it was too late to correct. 



Disappearance 
of the 

Tarahumara 
Frog 



by 

S.F. Hale 

Herpetologist 

C.R. Schwalbe 

National Biological Service 

J.L. Jar chow 

Sonora Pet Hospital, 

Tucson, AZ 

C.J. May 

Pima Community College 

C.H. Lowe 

University of Arizona 

T.B. Johnson 

Arizona Game and Fish 

Department 



In the spring of 1983 the last known 
Tarahumara frog in the United States was 
found dead. Overall, the species seems to be 
doing well in Mexico, although the decline of 
more northern populations are of concern. The 
Tarahumara frog (Rana tarahumarae) inhabits 
seasonal and permanent bedrock and bouldery 
streams in the foothills and main mountain mass 
of the Sierra Madre Occidental of northwestern 
Mexico. It ranges from northern Sinaloa, 
through western Chihuahua and eastern and 
northern Sonora, and until recently into extreme 
south-central Arizona (Fig. 1). Arizona locali- 
ties, all in Santa Cruz County, include three 
drainages in the Atascosa-Pajarito Mountains 
(Campbell 1931; Little 1940; Williams 1960) 
and three in the Santa Rita Mountains (Hale et 
al. 1977). 

Population Estimates, 1975-93 

We have drawn our review from museum 
records, the published literature, and reports, 
journal entries, and personal observations by 
the authors, other biologists, and knowledge- 
able persons. From May 1975 through June 
1977, we conducted an ecological, demograph- 
ic, and life-history study of the population at 
Big Casa Blanca Canyon (Santa Rita 
Mountains). 

Between 1980 and 1993, we visited 22 of 30 
historical Tarahumara frog localities. We sur- 



veyed 43 additional streams with potential habi- 
tat and found Tarahumara frogs at 25 new local- 
ities in Mexico. Localities were extensively 
searched, often both day and night, sometimes 
repeatedly. Frogs and tadpoles were counted, 
size-classed, and sexed when possible. Time, 
streamwater pH, air, substrate and water tem- 
peratures, habitat description and condition, and 
relative abundances of other aquatic vertebrates 
were noted. 

During the summers of 1982-83, rain sam- 
ples were collected at The Nature 
Conservancy's Sonoita Creek and Canelo Hills 
preserves for pH determination and heavy metal 
analysis. Both sites are within 22-56 km (14-35 
mi) of declining frog populations and 64-129 
km (40-80 mi) north and northwest of copper 
smelters. Streamwater samples from sites of 
declining populations in Sycamore and Big 
Casa Blanca canyons in Arizona and Carabinas 
Canyon in northeastern Sonora were also col- 
lected for pH and heavy metal analyses. 

Decline of Populations 

In April 1974, 27 dead and dying 
Tarahumara and leopard frogs were observed at 
Sycamore Canyon, Atascosa-Pajarito 
Mountains, the best-known and most frequently 
visited Tarahumara frog population. The last 
sightings of Tarahumara frogs in that range 
were in the summer of 1974. 



Our Living Resources — Reptiles and Amphibians 



139 



The decline of the Santa Rita Mountains 
population began in 1977 (Fig. 2). Total num- 
bers of frogs (adults and juveniles) captured 
plummeted from 252 in 1976 to 46 in 1977; 
estimated total population size fell from a max- 
imum 1,020 frogs to 625 (Hale and May 1983). 
In June 1977 some captured frogs became unre- 
sponsive and often died, apparently from the 
stress of capture, a response not previously 
observed. In 1978 no frogs marked in prior 
years, nor tiny larvae attributable to that year's 
breeding, were found. Larger tadpoles from 
1976-77 persisted. Twenty newly metamor- 
phosed frogs were observed in 1978 and 40 in 
1979; from 1980 to 1982 we saw one to three 
frogs attributable to those frogs. In spring 1983 
the last known Tarahumara frog in the United 
States was found dead. Repeated visits (some 
times yearly) to all former Arizona localities 
have yielded no additional sightings. 

Three of seven populations studied from 
1981 to 1986 in northern Sonora appeared 
healthy, with adult and juvenile frogs as well as 
both small and large larvae, suggesting a stable, 
reproductive population. Frogs were not seen at 
three other sites where they had been found in 
the 1970's and early 1980's. The last popula- 
tion, in Carabinas Canyon, Sierra El Tigre, 
which contained numerous frogs and tadpoles, 
was in the initial stages of a major decline when 
first observed in fall 1981. Within a year all 
frogs had disappeared from the downstream end 
of this population, but frogs in the upper portion 
of the drainage appeared to have suffered no 
decline in numbers through our most recent 
visit to the site in 1986. 

Carabinas Canyon frogs displayed clinical 
signs suggestive of heavy metal poisoning, 
including irregular muscular activity and failure 
of muscular coordination (ataxia), partial paral- 
ysis of the hind legs, dilated pupils unrespon- 
sive to light, and a loss of the righting response. 
The skin was often dry on the head and back. 
Symptoms were amplified by the stress of cap- 
ture and handling. Frogs displaying obvious 
signs of heavy metal poisoning were already 
dying. 

Field examinations of dead frogs showed no 
evidence of gross pathological disorders. Skin 
cultures showed no common pathogens; species 
representing probable normal skin flora and 
opportunistic secondary pathogens attacking a 
debilitated host were present. Histopathological 
examinations of five dying frogs (E. Jacobson, 
J. Hillis Miller Health Center, College of 
Veterinary Medicine, Gainesville, Florida) 
revealed no gross pathologies (Hale and May 
1983; Hale and Jarchow 1988). 

Populations of Chiricahua and Yavapai leop- 
ard frogs (Rana chiricahuensis and R. yava- 
paiensis) declined with the Tarahumara frog 




where they occurred together, although leopard 
frogs were not eliminated from most 
Tarahumara frog sites. In Sycamore Canyon, 
Chiricahua leopard frogs have managed to 
maintain a small but viable population near 
Yank Spring, but numbers decrease downstream 
in previously favorable leopard frog habitat. 
The Chiricahua leopard frog has experienced 
catastrophic declines elsewhere, and is in dan- 
ger of disappearing from most of its range 
(Clarkson and Rorabaugh 1989). 

Rain collected at the Sonoita Creek and 
Canelo Hills preserves in the summers of 1982 

250- 



Fig. 1. Range of the Tarahumara 
frog, Rana tarahumarae. Copper 
smelters are at Douglas, AZ (now 
closed), and Cananea and 
Nacozari, Sonora. Historical loca- 
tions include both surveyed popu- 
lations that appeared stable, and 
unvisited historical localities 
(Campbell 1931; Little 1940; 
Williams 1960; Hale et al. 1977; 
Hale and May 1983; Hale and 
Jarchow 1988). 



200 



150 



100- 



50 



Juveniles 
Adults 



I 



75 77 79 81 83 85 87 
Year 



91 93 



Fig. 2. Number of Tarahumara 
frogs captured 1975-93, Big Casa 
Blanca Canyon, Santa Rita 
Mountains. Santa Cruz County, 
AZ (Hale and May 1983). 



140 



Reptiles and Amphibians — Our Living Resources 



Tarahumara frog (Rana tarahu- 
marae) in Mexico. 




For further information: 

S.F. Hale 

Hcrpetologist 

1 39 W. Suffolk Dr. 

Tucson, AZ 85704 



and 1983 was consistently very acidic, attrib- 
uted primarily to particulates produced by a 
copper smelter in Douglas, Arizona (Blanchard 
and Stromberg 1987), which has since been 
shut down. The alkaline soils in the area may 
buffer the streams from the acid rain; stream pH 
values were always slightly basic. 

Analyses of water from affected streams 
showed consistently elevated levels of cadmi- 
um, a toxic metal, especially in relation to lev- 
els of the essential metal, zinc. In several 
species of vertebrates, sensitivity to cadmium 
toxicity is reduced with zinc supplementation 
(Supplee 1963; Webb 1972). At Sycamore 
Canyon and Big Casa Blanca Canyon localities, 
frogs survived longest near springs where zinc 
concentrations were highest. Levels of arsenic 
in streamwater were occasionally elevated 
(Hale and Jarchow 1988). 

Although the proximity of operating copper 
smelters is correlated with population declines 
in Tarahumara and leopard frogs, exact causes 
of declines are not clear. No declines in frogs 
were noted until the 1970's, yet copper smelter 
emissions were much higher in the areas of 
declines in the early 1900's than recently. One 
of our hypotheses that accounts for the timing 
of the declines relates them to a long-term 
leaching of acid-soluble zinc from canyon 
walls, accumulation of insoluble cadmium in 
stream sediment, and sediment accumulation in 
stream pools from infrequent heavy rains before 
declines. 

In southern and central Sonora, ranid frog 
populations appeared stable and reproductive at 
least through 1986; no population declines or 
extirpations were noted, either of Tarahumara or 
leopard frogs. Populations visited since 1986 do 
not appear to be declining. 

Conclusions 

We are confident that the Tarahumara frog 
no longer occurs in the United States, based 
upon repeated surveys of historical and poten- 
tial habitat in southern Arizona. Although 
repeated surveys since 1983 in Mexico have not 
been as extensive as in the United States, sites 
visited in central and southern Sonora apparent- 
ly continue to support healthy frog populations. 

We conclude that the Tarahumara frog is not 



threatened with extinction throughout its range 
at this time, although the sudden declines and 
local extirpations in northern populations, coin- 
cident with declines of leopard frogs, are a seri- 
ous concern. 

State and federal resource management 
agencies in both Arizona and Sonora. Mexico, 
with independent biologists and the Arizona- 
Sonora Desert Museum (ASDM) and Centro 
Ecologico de Sonora have formed the 
Tarahumara Frog Reestablishment Oversight 
Group. This group proposes to reestablish the 
Tarahumara frog in selected historical sites and 
maintain captive frog populations at ASDM and 
elsewhere to provide stock for additional rein- 
troduction. By intensively monitoring reintro- 
duced populations and measuring important 
environmental variables we hope to determine 
the cause of declines in native ranid frogs in this 
area. Rain, streamwater, and air quality will be 
assessed continuously at each site, including 
pH, heavy metals, solar radiation (especially 
ultraviolet), and air particulates. Stream bottom 
substrate and tissue samples from frogs and frog 
prey and predator species will be sampled for 
heavy metals. Only after the causes of the 
declines have been identified and corrected can 
we expect long-term reestablishment of 
Tarahumara frogs and recovery of leopard 
frogs. 

References 

Blanchard. C.L.. and M. Stromberg. 1987. Acidic precipita- 
tion in southeastern Arizona: sulfate, nitrate and trace- 
metal deposition. Atmospheric Environment 21:2375- 
2381. 

Campbell. B. 1931. Rana tarahumarae. a frog new to the 
United States. Copeia 1931:164. 

Clarkson. R.W.. and J.C. Rorabaugh. 1989. Status of leop- 
ard frogs (Rana pipiens complex: Ranidae) in Arizona 
and southeastern California. Southwestern Naturalist 
34:531-538. 

Hale. S.F.. and J.L. Jarchow. 1988. The status of the 
Tarahumara frog (Rana tarahumarae) in the United 
States and Mexico: Part 2. C.R. Schwalbe and T.B. 
Johnson, eds. Report to Arizona Game and Fish 
Department. Phoenix, and Office of Endangered Species. 
U.S. Fish and Wildlife Service. Albuquerque. NM. 101 
pp. 

Hale. S.F., and C.J. May. 1983. Status report for Rana 
tarahumarae Boulenger. Arizona Natural Heritage 
Program. Tucson. Report to Office of Endangered 
Species. U.S. Fish and Wildlife Service. Albuquerque. 
NM. 99 pp. 

Hale. S.F. F. Retes, and T.R. Van Devender. 1977. New pop- 
ulations of Rana tarahumarae (Tarahumara frog) in 
Arizona. Journal of the Arizona Academy of Science 
11:134-135. 

Little. E.L., Jr. 1940. Amphibians and reptiles of the 
Roosevelt Reservoir area, Arizona. Copeia 1940:260- 
265. 

Supplee. W.C. 1963. Antagonistic relationship between 
dietary cadmium and zinc. Science 139:1 19-120. 

Webb, M. 1972. Protection by zinc against cadmium toxic- 
ity. Biochemical Pharmacology 21:2767-2771. 

Williams, K.L. 1960. Taxonomic notes on Arizona herpeto- 
zoa. Southwestern Naturalist 5:25-36. 









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Overview 



The inescapable conclu- 
sion from the data pre- 
sented in this section is that within historical 
time, native fish communities have undergone 
significant and adverse changes. These changes 
generally tend toward reduced distributions, 
lowered diversity, and increased numbers of 
species considered rare. These changes have 
been more inclusive and more dramatic in the 
arid western regions where there are primarily 
endemic (native) species, but similar, though 
more subtle changes, have occurred throughout 
the country. These trends are the same whether 
one focuses on faunas (Johnson; Starnes; and 
Walsh et al., this section) or on populations or 
genetic variation within a single species 
(Marnell; Miller et al.; and Philipp and 
Claussen, this section). Changes in fish commu- 
nities may be indicative of the overall health of 
an aquatic system; some species have narrow 
habitat requirements. 

The fact that fish populations have changed 
over historical time should not come as any 
great surprise. We have massively modified fish 
habitat through the very water demands that 
define our society (domestic, agricultural, and 
industrial water supplies; waste disposal; power 
generation; transportation; and flood protec- 
tion). All of these activities have resulted in 



controlling or modifying the flow or degrading 
the quality of natural waters. In addition, almost 
all contaminants ultimately find their way into 
the aquatic system. Species of fishes that have 
evolved under the selection pressures imposed 
by natural cycles have often been unable to 
adapt to the changes imposed on them as a 
result of human activities. 

Physical and chemical changes in their habi- 
tats are not the only stresses that fishes have 
encountered over time. Through fish manage- 
ment programs, the aquarium trade, and acci- 
dental releases, many aquatic species have been 
introduced to new areas far beyond their native 
ranges. Although these introductions were often 
done with the best of intentions, they have 
sometimes subjected native fish species to new 
competitors, predators, and disease agents that 
they were ill-equipped to withstand. 

The data presented by Philipp and Claussen 
(this section) further suggest that managed fish 
populations (hatchery-stocked populations) 
have a lower genetic diversity than unmanaged 
populations. In other words, theoretically, the 
smaller the gene pool, the less likely a species 
may be able to adapt to changing environmental 
conditions. 

It appears unlikely that the forces that have 
led to these changes in our fish fauna will lessen 



Science Editor 

O. Eugene Maughan 

National Biological 

Service 

Arizona Cooperative Fish 

and Wildlife Research Unit 

University of Arizona 

Tucson, AZ 85721 



142 



Fishes — Our Living Resources 



significantly in the immediate future. Therefore, 
if we are to preserve the diversity and adaptive 
potential of our fishes, we must understand 
much more of their ecology. Vague generaliza- 
tions about habitat requirements or the results of 
biotic interactions are no longer enough. We 



must know quantitatively and exactly how fish- 
es use habitat and how that use changes in the 
face of biotic pressures. Only when armed with 
such information are we likely to reduce the 
current trends among our native fishes. 



Imperiled 

Freshwater 

Fishes 

by 

James E. Johnson 
National Biological Service 



Figure. Number of fishes consid- 
ered imperiled and number of 
native freshwater fishes of the con- 
tiguous United States by state 
(redrawn from Warren and Burr 
1994). 



The United States is blessed with perhaps 
800 species of native freshwater fishes (Lee 
et al. 1980; Moyle and Cech 1988; Warren and 
Burr 1994). These fishes range from old, primi- 
tive forms such as paddlefish, bowfin, gar, and 
sturgeon, to younger, more advanced fishes, 
such as minnows, darters, and sunfishes. They 
are not equally distributed across the nation, but 
tend to concentrate in larger, more diverse envi- 
ronments such as the Mississippi River drainage 
(375 species; Robison 1986; Warren and Burr 
1994). Drainages that have not undergone 
recent geological change, such as the Tennessee 
and Cumberland rivers, are also rich in native 
freshwater fishes (250 species; Stames and 
Etnier 1986). Fewer native fishes are found in 
isolated drainages such as the Colorado River 
(36 species; Carlson and Muth 1989). More arid 
states west of the 100th meridian average about 
44 native fish species per state, while states east 
of that boundary average more than three times 
that amount (138 native species; Figure). 

Extinction, dispersal, and evolution are natu- 
rally occurring processes that influence the 
kinds and numbers of fishes inhabiting our 
streams and lakes. More recent human-related 
impacts to aquatic ecosystems, such as 
damming of rivers, pumping of aquifers, addi- 
tion of pollutants, and introductions of 



non-native species, also affect native fishes, but 
at a more rapid rate than natural processes. 
Some fishes are better able to withstand these 
rapid changes to their environments or are able 
to find temporary refuge in adjacent habitats; 
fishes that lack tolerance or are unable to retreat 
face extinction. 

In 1979 the Endangered Species Committee 
of the American Fisheries Society (AFS) devel- 
oped a list of 251 freshwater fishes of North 
America judged in danger of disappearing 
(Deacon et al. 1979), 198 of which are found in 
the United States. A decade later, AFS updated 
the list (Williams et al. 1989), noting 364 taxa 
of fishes in some degree of danger, 254 of 
which are native to the United States. Both AFS 
lists used the same endangered and threatened 
categories defined in the Endangered Species 
Act of 1973, and added a special concern cate- 
gory to include fishes that could become threat- 
ened or endangered with relatively minor dis- 
turbances to their habitat. These imperiled 
native fishes are the first to indicate changes in 
our surface waters; thus their status provides us 
with a method of judging the health of our 
streams and lakes. This article compares the two 
AFS data sets to assess the trends in the status 
of freshwater fishes in the United States over 
the past decade. 







Our Living Resources — Fishes 



143 



Basis of the American Fisheries 
Society Listings 

The 1979 and 1989 AFS listings were based 
entirely on biological considerations throughout 
the geographic range of the taxon and ignored 
jurisdictional or political considerations. For 
example, the johnny darter {Etheostoma 
nigrum) is a small darter found in clear streams 
from the East coast to the Continental Divide; 
the species reaches the western periphery of its 
range in Colorado. Johnny darters are rare in 
Colorado, which recognizes the species' rarity 
(Johnson 1987). Throughout most of its range, 
however, the johnny darter is common and thus 
was not included in the AFS listing. Only those 
taxa that appear imperiled are included in the 
lists; populations were not considered unless 
they were distinct enough to be recognized as 
subspecies. 

The preliminary 1979 AFS listing was 
obtained by asking knowledgeable fishery sci- 
entists which fishes should be included. Those 
taxa were added to a 1972 listing of protected 
fishes (Miller 1972) that was then sent out to 
every state and to selected federal agencies for 
review. 

The native fish faunas of some areas of the 
country are better studied than others and may 
therefore be better represented in the listing. 
The 1989 listing used knowledgeable biologists 
but not extensive agency review to build upon 
the 1979 listing. These two data bases provide 
the best information presently available on rare 
native fishes of the United States. 

Changes in the Status of Native 
Freshwater Fishes, 1979-89 

Analysis of the 1989 list provides some 
basic information on the status and trends of the 
native fishes of the United States. About one- 
fourth of our native freshwater fishes are per- 
ceived to be imperiled. Ninety-three percent of 
imperiled species are in trouble because of the 
deteriorating quality of the aquatic habitats on 
which they depend; this deterioration results 
from physical, chemical, and biological effects 
to our surface waters and underground aquifers. 
Overuse, introduction of non-native species, 
disease, and other problems that also affect our 
native fishes cause much less endangerment 
than habitat destruction. 

The increase of taxa of fishes between the 
1979 (189 taxa) and 1989 (254 taxa) AFS list- 
ings does not include 19 taxa that were removed 
from the 1989 listing because of extinction, tax- 
onomic revisions, or better information on sta- 
tus. Seventy-five imperiled taxa that did not 
appear in the 1979 AFS listing were added to 



Species 


Population trend 


Pallid sturgeon (Scaphirhynchus albus) 


Declined 


Longjaw Cisco (Coregonus alpenae) 


Extinct 


Deepwater Cisco (C. johannae) 


Extinct 


Blackfin Cisco (C. nigripinnis) 


Extinct 


Alvord cutthroat trout (Oncorhynchus clarki ssp.) 


Extinct 


Fish Creek Springs tui chub (Gila bicolor euchila) 


Improved 


Independence Valley tui chub (G.b. isolata) 


Extinct 


Thicktail chub (G. crassicauda) 


Extinct 


Chihuahua chub (G. nigrescens) 


Improved 


Least chub (lotichthys phlegethontis) 


Declined 


White River spinedace (Lepidomeda albivallis) 


Declined 


Cape Fear shiner (Nolropis mekistocholas) 


Declined 


Blackmouth shiner (N. melanostomus) 


Declined 


Oregon chub (Oregonichthys crameri) 


Declined 


Blackside dace (Phoxinus cumberlandensis) 


Declined 


Loach minnow (Rhinichthys cobilis) 


Declined 


White River sucker (Catostomus clarki intermedius) 
Zuni bluehead sucker (C. discobolus yarrow!) 


Declined 
Improved 


Shortnose sucker (Chasmistes brevirostris) 


Declined 


June sucker (C. Hows mictus) 


Declined 


Lost River sucker {Deltistes luxatus) 


Declined 


Razorback sucker (Xyrauchen texanus) 


Declined 


Pygmy madtom (Noturus stanauli) 


Declined 


Alabama cavefish (Speoplatyrhinus poulsoni) 


Declined 


Preston springfish (Crenichthys baileyi albivallis) 


Declined 


White River springfish (C.b. baileyi} 


Declined 


Moorman springfish (C.b. thermophilus) 


Declined 


Railroad Valley springfish (C. nevadae) 


Declined 


Devils Hole pupfish (Cyprinodon diabolis) 


Improved 


Desert pupfish (C. macularius) 


Declined 


Amistad gambusia (Gambusia amistadensis) 


Extinct 


San Marcos gambusia (G georgei) 


Extinct 


Gila topminnow (Poeciliopsis occidentalis) 


Improved 


Spring pygmy sunfish (Elassoma sp. ) 


Improved 


Sharphead darter (Etheostoma acuticeps) 


Improved 


Amber darter (Percina antesella) 


Declined 


Blue pike (Stizostedion vitreum glaucum) 


Extinct 


Utah Lake sculpin (Cottus echinatus) 


Extinct 


Shoshone sculpin (C. greenei) 


Declined 



Table. Population trends for 
endangered, threatened, and spe- 
cial concern freshwater fishes of 
the United States whose status 
changed between 1979 and 1989 
(Williams et al. 1989). 



the 1989 AFS listing, an increase of 38% in a 
single decade. In addition, the status of 39 fish- 
es was changed: 7 taxa improved (e.g., changed 
from threatened to special concern), 22 taxa 
declined, and 10 taxa were recognized as 
extinct (Table). No fish was removed from the 
1989 AFS listing because of successful recov- 
ery efforts, indicating that our freshwater fishes 
continue to decline overall, and factors causing 
those changes appear difficult to reverse. 

The relation between declining aquatic habi- 
tats and fishes facing extinction is not as simple 
as might be expected. Species with limited dis- 
tributions are more likely to be jeopardized by 
changes in their local aquatic habitats than are 
species with extensive ranges. Many fishes on 
the lists have local distributions, and a few, such 
as the Clear Creek gambusia (Gambusia hete- 
rochir) and Devils Hole pupfish {Cyprinodon 
diabolis), are limited to a single spring. These 
unique fishes could be lost by a single, isolated 
event. Some of the widespread species included 
in the listings — such as paddlefish {Polyodon 
spathula) and six taxa of sturgeons — depend on 
large rivers, and their inclusion indicates wide- 
spread threats to these extensive habitats. 

States with the most listed (imperiled) 
species include California (42), Tennessee (40), 
and Nevada (39). Somewhat fewer listed fishes 
are found in Alabama (30), Oregon (25), Texas 
(23), Arizona (22), Virginia (21), North 



144 



Fishes — Our Living Resources 



For further information: 

James E. Johnson 

National Biological Service 

Arkansas Cooperative Research 

Unit 

Department of Biological Sciences 

University of Arkansas 

Fayetteville, AR 72701 



Carolina (21), New Mexico (20), and Georgia 
(20; Figure). Regionally, the Southwest has the 
highest mean number of fish species listed per 
state (22.5), closely followed by the Southeast 
(19.3); the northeastern states have the lowest 
mean number of native fish species in trouble 
(3.7). Nearly half (48%) of the southwestern 
native fishes are jeopardized, followed by fishes 
of the Northwest (19%), the Southeast (10%), 
the Midwest (6.4%), the central states (5.9%), 
and the Northeast (4.3%; Warren and Burr 
1994). 

The AFS will likely update its listing of 
native fishes in peril toward the end of this 
decade, thus providing us with more than 20 
years of information on the status of these fish- 
es, a short time in the overall life of a species 
but a good data base upon which to evaluate the 
environmental health of our streams and lakes. 
If the trend over the last decade continues, we 
can expect a further decline in the richness of 
our native fishes. In addition, as aquatic habitat 
deterioration becomes more extensive, we can 
expect to see an increase in the listing of wide- 
spread fishes. 

References 

Carlson, C.A.. and R.T. Muth. 1989. The Colorado River: 
lifeline of the American Southwest. Pages 220-239 in 
D. R Dodge, ed. Proceedings of the International Large 



Rivers Symposium. Canadian Journal of Fisheries and 
Aquatic Sciences, Special Publ. 106. 

Deacon, J.E., G. Kobetich, J.D. Williams, S. Contreras, et 
al. 1979. Fishes of North America endangered, threat- 
ened, or of special concern: 1979. Fisheries 4(2):30-44. 

Johnson, J.E. 1987. Protected fishes of the United States 
and Canada. American Fisheries Society. Bethesda. MD. 
42 pp. 

Lee, D.S., C.R. Gilbert, C.H. Hocutt, R.E. Jenkins. D.E. 
McAllister, and J.R. Stauffer, Jr. 1980. Atlas of North 
American freshwater fishes. North Carolina State 
Museum of Natural History. 254 pp. (Reissued 1981 with 
appendix; 867 pp.) 

Miller, R.R. 1972. Threatened freshwater fishes of the 
United States. Transactions of the American Fisheries 
Society 101(2):239- 252. 

Moyle, P.B., and J.J. Cech, Jr. 1988. Fishes: an introduction 
to ichthyology. Prentice Hall. Englewood Cliffs, NJ. 559 
pp. 

Robison, H.W. 1986. Zoogeographic implications of the 
Mississippi River basin. Pages 267-285 in C.H. Hocutt 
and E.O. Wiley, eds. The zoogeography of North 
American freshwater fishes. John Wiley and Sons, Inc., 
New York. 

Starnes, W.C., and D.A. Etnier. 1986. Drainage evolution 
and fish biogeography of the Tennessee and Cumberland 
rivers drainage realm. Pages 325-361 in C.H. Hocutt and 
E.O. Wiley, eds. The zoogeography of North American 
freshwater fishes. John Wiley and Sons, New York. 

Warren, M.L.. and B.M. Burr. 1994. Status of freshwater 
fishes of the United States: overview of an imperiled 
fauna. Fisheries 19(1):6-18. 

Williams, J.E.. J.E. Johnson. D.A. Hendrickson, S. 
Contreras-Balderas, J.D. Williams, M. Navarro- 
Mendoza. D.E. McAllister, and J.E. Deacon. 1989. 
Fishes of North America endangered, threatened, or of 
special concern: 1989. Fisheries 14(6):2-20. 



Southeastern 

Freshwater 

Fishes 



by 

Stephen J. Walsh 

Noel M. Burkhead 

James D. Williams 
National Biological Service 



North America has the richest fauna of tem- 
perate freshwater fishes in the world, with 
about 800 native species in the waters of 
Canada and the United States. The center of this 
diversity is in the southeastern United States, 
where as many as 500 species may exist (62% 
of the continental fauna north of Mexico). Many 
coastal marine species also enter fresh waters of 
the Southeast, and at least 34 foreign fish 
species are established in the region. 

Although freshwater fishes of the United 
States are better studied than any fish fauna of 
comparable scope in the world (Lee et al. 1980; 
Hocutt and Wiley 1986; Matthews and Heins 
1987; Page and Burr 1991; Mayden 1992), large 
gaps exist in scientific knowledge about the 
biology and ecology of most species. New 
species are still being discovered, and the tax- 
onomy of other species is being refined. 

Seriously declining populations of freshwa- 
ter fishes in the United States concern the sci- 
entific community (Deacon et al. 1979; 
Williams et al. 1989; Moyle and Leidy 1992; 
Warren and Burr 1994). This article briefly 
summarizes the current conservation status of 
southeastern freshwater fishes; the Southeast is 
emphasized because of its important fish biodi- 
versity and to focus attention on the growing 




Principal causes of declining fish resources in the 
Southeast are due to habitat perturbations, such as loss of 
forested stream cover, mining activities, and impound- 
ments, as at this site in northern Georgia. 

problem of adverse human impacts on the 
region's aquatic habitats (Mount 1986; 
Burkhead and Jenkins 1991; Etnier and Starnes 
1991; Warren and Burr 1994). 

Hydrologic Regions 

The southeastern United States as defined 
here is delimited on the north and west by the 
Ohio and Mississippi rivers. The following 
hydrologic regions (Fig. 1) are defined on the 
basis of common geophysical characteristics 
and similar fish faunas of the drainages within 



Our Living Resources — Fishes 



145 



each region (Hocutt and Wiley 1986): (a) 
Atlantic Slope — coastal waters from the 
Roanoke River (Virginia) southward to the 
Altamaha River (Georgia); (b) Peninsular — 
waters from the Satilla River (Georgia) to the 
Ochlockonee River (Florida); (c) Lower 
Apalachicola Basin — waters from the 
Apalachicola River (Florida) westward to the 
Perdido River (Alabama); (d) Lower Mobile 
Basin — lowland portions of the Tombigbee and 
Alabama rivers and tributaries (Alabama and 
Mississippi); (e) Lower Mississippi — the 
Mississippi River and its eastern tributaries 
below the Ohio River (Mississippi, Tennessee, 
and Kentucky); (f) Interior Plateau — upland 
waters of the middle and lower Ohio River and 
southern tributaries, including the lower 
Cumberland and Tennessee rivers (Kentucky 
and Tennessee); and (g) Southern Appalachians 
— upland waters of the mountains in the geo- 
logical provinces known as the Cumberland 
Plateau, Valley and Ridge, Blue Ridge, and 
Piedmont, south of the Kanawha (West 
Virginia) and Roanoke rivers. Many fishes are 
widely distributed in the Southeast and occur in 
two or more hydrologic regions. 

Imperiled Freshwater Fishes 

The Southeast has about 485 known species 
of native freshwater fishes, representing 27 
families. Most of the diversity of the southeast- 
ern fish fauna is in five families: the darters and 
perches (family Percidae; 31.3%); the minnows 
(family Cyprinidae; 29.7%); the madtoms and 
bullhead catfishes (family Ictaluridae; 6.8%); 
the suckers (family Catostomidae; 6.6%); and 
the sunfishes and basses (family Centrarchidae; 
5.8%). The greatest diversity is in the 
Appalachian Mountains and Interior Plateau 
(Fig. 1 ), but other regions of the Southeast also 
harbor many more species than do similar-sized 
geographic areas elsewhere in the United 
States. 

As of January 1994 the U.S. Fish and 
Wildlife Service (USFWS) had designated 15 
southeastern fish species as endangered and 1 2 
as threatened, representing 6% of the entire 
regional fish fauna. Ninety-three fish taxa 
(19%) are imperiled (endangered, threatened, or 
of special concern) in the Southeast, including 
proposed listings and those recognized by other 
authors (Williams et al. 1989). During the past 
25 years, only seven species were upgraded by 
the USFWS, mainly because of discovery of 
new populations, inadequate knowledge at the 
time of listing, or invalid taxonomy. No endan- 
gered or threatened species have been delisted. 
A steady upward trend in designation of imper- 
iled southeastern fishes has occurred in the last 
20 years (Fig. 2); the number of species con- 






No. of 
species 


% 
imperiled 


K Southern Appalachians 
Interior Plateau 


350 
229 


18.3 
11.4 


■H Lower Mississippi Basin 
1 1 Lower Mobile Basin 


183 
161 


6.0 

4.9 


Lower Apalachicola Basin 126 
!■ Peninsular 97 


6.3 
4.1 


68S Atlantic Slope 


141 


7.1 



sidered imperiled by the USFWS increased 
from 3 (less than 1%) in 1974 to 84 (17%) in 
1994 (USFWS listings only). During the 10- 
year period from 1979 to 1989, the number of 
species considered imperiled by the American 
Fisheries Society increased from 63 (13%) to 81 
(17%; Fig. 2). 

An alarming 21% of the nearly 300 species 
of minnows and darters are imperiled in the 
Southeast. Considered alone, more than 30% of 
the 150 species of darters are in trouble, repre- 
senting the highest total number of species in 
any one family. Madtom catfishes (genus 
Noturus) are also disproportionally imperiled 
among large families of more than 30 species 
(Etnier and Starnes 1991; Warren and Burr 
1994). Among smaller groups of fishes, the 
most severe status is among the sturgeons and 
paddlefish, where seven of the eight (86%) 
southeastern species are in jeopardy. In terms of 
ecological requirements, most imperiled species 
are those that live in small to large creeks and 
small rivers, are closely associated with clean 
stream-bottom substrates, or are isolated in 
spring and cave environments. 

On a regional scale, the greatest number of 
imperiled species occurs in the highland areas 
of the Appalachians and Interior Plateau, 



100 



80 



9- 60 



40 



20 





81 


84 




71^- 


76 


45/^ 


' 59 






3_USENS-^ 


74 76 78 80 82 84 86 
Year 


88 90 92 


94 



Fig. 1. Total numbers of freshwa- 
ter fishes and percentage imper- 
iled by hydrographic region of the 
southeastern United States. 



Fig. 2. Total numbers of imperiled 
fishes in the Southeast during the 
last 20 years, as recognized by the 
American Fisheries Society (AFS) 
and the U.S. Fish and Wildlife 
Service (USFWS). Numbers repre- 
sent imperiled species during years 
of listing activity. 



146 



Fishes — Our Living Resources 



Spottin chub 












Former distribution (pre-1930's) 










xT"^ -* 










y^ Virginia r^2, 


CO 




Kentucky 






f*25f^ 


I — ■// ® 








#C-— 


l^v^ y — 


•$ 








T^/J^ 




CD 


Tennessee 






'..J- 


*-^\/ ^ s ~t = °*< / ^ 
















kf/l^ 


/Ja> 




^pi 


c 


JKTv. \ 




j^ 






\ I I Hange 




^ 


Georgia 




\ o Collection sites 



Current distribution 




Fig. 3. An example of habitat frag- 
mentation, decline, and isolation 
of populations of a southeastern 
freshwater fish, the endangered 
spotfin chub (Cyprinella 
monacha). Former (pre-1930's) 
and present range in yellow. 




Tangerine darter (Percina auranti- 
aca). 




Mountain redbelly dace (Phoxinus 
oreas). 



followed by the Coastal Plain subregions (Fig. 
1 ). This geographic trend is correlated with both 
a high level of diversity in the respective hydro- 
logic regions and the quite localized or endem- 
ic distributions of many species. Especially 
important are a number of watersheds that har- 
bor many species confined within those 
drainages; these watersheds include the 
Tennessee River, the Mobile Basin, the 
Cumberland River, and the Roanoke and James 
rivers (Warren and Burr 1994). Most jeopar- 
dized species have restricted distributions, but 
the number of more geographically widespread 
species that are disappearing from large por- 
tions of their ranges is increasing. 

Two species of southeastern fishes have 
become extinct in the last century: the harelip 
sucker (Moxostoma lacerum) and the whiteline 
topminnow (Fundulus albolineatus). At least 
one other species, the least darter {Etheostoma 
microperca), has disappeared from the southern 
portion of its range that falls within the region 
covered here. The slender chub (Erimystax 
cahni) has not been seen since 1987 and may be 
near extinction. Two other species peripheral to 
the Southeast are feared extinct: the Scioto 
madtom (Noturus trautmani) and the Maryland 
darter (Etheostoma sellare; Etnier 1994). 

The declining status of freshwater fishes 
among divergent taxonomic groups and across 



broad habitat types and geographic areas is 
interpreted as evidence for widespread and per- 
vasive threats to the entire North American fish 
fauna (Moyle and Leidy 1992; Warren and Burr 
1994). In the Southeast, fish declines are the 
result of the same factors that cause global dete- 
rioration of aquatic resources, primarily habitat 
loss and degraded environmental conditions. 
The principal causes of freshwater fish impedi- 
ment in the Southeast and other areas of the 
United States are dams and channelization of 
large rivers, urbanization, agriculture, defor- 
estation, erosion, pollution, introduced species, 
and the cumulative effects of all these factors 
(Moyle and Leidy 1992; Warren and Burr 
1994). The most insidious threat to southeastern 
fishes is sedimentation and siltation resulting 
from poor land-use patterns that eliminate suit- 
able habitat required by many bottom-dwelling 
species. Cumulative effects of physical habitat 
modifications have caused widespread frag- 
mentation of many fish populations in the 
Southeast (Fig. 3), presenting difficult chal- 
lenges for those trying to reverse and restore 
diminished fish stocks. 

Aquatic resources are often resilient and 
capable of recovery, given favorable conditions. 
Conservation of southeastern fishes will require 
significant changes in land management and 
socioeconomic factors (Moyle and Leidy 1992; 
Warren and Burr 1994), but such changes are 
necessary to stem future losses of biodiversity. 
The first step required is to improve public edu- 
cation on the value and status of native aquatic 
organisms. For resource managers and policy 
makers, increased efforts must be made to 
assume proactive management of entire water- 
sheds and ecosystems; establish networks of 
aquatic preserves; restore degraded habitats; 
establish long-term research, inventory, and 
monitoring programs on fishes; and adopt 
improved environmental ethics concerning 
aquatic ecosystems (Warren and Burr 1994). 
The southeastern fish fauna is a national trea- 
sure of biodiversity that is imminently threat- 
ened. If this precious heritage is to be passed on, 
its stewardship must be improved through coop- 
erative actions of all public and private sectors 
within the region. 

References 

Burkhead, N.M., and R.E. Jenkins. 1991. Fishes. Pages 
321-409 in Virginia's Endangered Species: Proceedings 
of a Symposium. McDonald and Woodward Publishing 
Co.. Blacksburg.VA. 672 pp. 

Deacon, J.E.. G. Kobetich. J.D. Williams. S. Contreras. et 
al. 1979. Fishes of North America endangered, threat- 
ened, or of special concern: 1979. Fisheries 4(2):30-44. 

Etnier, D.A. 1994. Our southeastern fishes — what have we 
lost and what are we likely to lose. Southeastern Fishes 
Council Proceedings 29:5-9. 

Etnier. D.A., and W.C. Starnes. 1991. An analysis of 
Tennessee's jeopardized fish taxa. Journal of the 
Tennessee Academy of Science 66(4): 1 29- 1 33. 



Our Living Resources — Fishes 



147 



Hocutt, C.H., and E.O. Wiley, eds. 1986. The zoogeography 
of North American freshwater fishes. John Wiley and 
Sons, Inc., New York. 866 pp. 

Lee, D.S., C.R. Gilbert, C.H. Hocutt, R.E. Jenkins. D.E. 
McAllister, and J.R. Stauffer, Jr. 1980. Atlas of North 
American freshwater fishes. North Carolina State 
Museum of Natural History. Raleigh. 854 pp. (Reissued 
in 1981 with appendix; 867 pp.) 

Matthews, W.J., and D.C. Heins, eds. 1987. Community and 
evolutionary ecology of North American stream fishes. 
University of Oklahoma Press, Norman. 310 pp. 

Mayden. R.L., ed. 1992. Systematics, historical ecology, 
and North American freshwater fishes. Stanford 
University Press. CA. 969 pp. 

Mount. R.H.. ed. 1986. Vertebrate animals of Alabama in 
need of special attention. Alabama Agricultural 
Experiment Station. Auburn University. 124 pp. 



Moyle, P.B.. and R.A. Leidy. 1992. Loss of biodiversity in 
aquatic ecosystems: evidence from fish faunas. Pages 
127-169 in PL. Fiedler and S.K. Jain, eds. Conservation 
biology: the theory and practice of nature conservation, 
preservation and management. Chapman and Hall, New 
York. 507 pp. 

Page. L.M., and B.M. Burr. 1991. A field guide to freshwa- 
ter fishes of North America north of Mexico. Peterson 
field guide series. Houghton Mifflin Co.. Boston. MA. 
432 pp. 

Warren. M.L., Jr., and B.M. Burr. 1994. Status of freshwa- 
ter fishes of the United States: overview of an imperiled 
fauna. Fisheries 19(1):6-18. 

Williams. J.E.. J.E. Johnson. D.A. Hendrickson. S. 
Contreras-Balderas, J.D. Williams. M. Navarro- 
Mendoza, D.E. McAllister, and J.E. Deacon. 1989. 
Fishes of North America endangered, threatened, or of 
special concern: 1989. Fisheries 14(6):2-20. 



For further information: 

Stephen J. Walsh 

National Biological Service 

Southeastern Biological Science 

Center 

7920 NW 71st St. 

Gainesville. FL 32653 



Species are composed of genetically diver- 
gent units usually interconnected by some 
(albeit low) level of gene flow (Soule 1987). 
Because of this restriction in gene flow, natural 
selection can genetically tailor populations to 
their environments through the process of local 
adaptation (Wright 1931). 

Because freshwater and anadromous (i.e., 
adults travel upriver from the sea to spawn) fish- 
es are restricted by the boundaries of their 
aquatic habitats, genetic subdivisions may be 
more pronounced for these vertebrates than for 
others. Consequently, managers of programs for 
these species must realize that the stock (i.e., 
local discrete populations), and not the species 
as a whole, must be the units of primary man- 
agement concern (Kutkuhn 1981). 

Genetic variability in a species occurs both 
among individuals within populations as well 
as among populations (Wright 1978). Variation 
within populations is lost through genetic drift 
(see glossary; Allendorf et al. 1987), a process 
increased when population size becomes small. 
Variation among populations is lost when previ- 
ously restricted gene flow between populations 
is increased for some reason (e.g., stocking, 
removal of natural barriers such as waterfalls); 
differentiation between populations is lost as a 
result of the homogenization of two previously 
distinct entities (Altukhov and Salmenkova 
1987; Campton 1987). 

Beyond this loss of genetic variation, mixing 
two groups can result in outbreeding depres- 
sion, which is the loss of fitness in offspring that 
results from the mating of two individuals that 
are too distantly related (Templeton 1987). This 
loss in fitness is caused by the disruption of the 
process that produced advantageous local adap- 
tations through natural selection. Inbreeding 
depression, on the other hand, is the loss of fit- 
ness produced by the repeated crossing of relat- 
ed organisms. The area of optimal relatedness 
occurs between inbreeding depression and out- 
breeding depression. 



Loss of Genetic Integrity 
Through Stocking 

Many sportfish populations are managed by 
using a combination of harvest regulation, habi- 
tat manipulation, and stocking. Jurisdiction for 
these activities falls to federal, state, tribal, and 
local governments, as well as private citizens. 
Many resource managers in the past were 
unaware of the long-term consequences that 
stocking efforts would have on the genetic 
integrity of local populations (Philipp et al. 
1993). 

Fish introductions can be classified into 
three types: non-native introductions, in which a 
given species of fish is introduced into a body of 
water outside its native range (regardless of any 
political boundaries); stock transfers, in which 
fish from one stock are introduced into a water 
body in a different geographic region inhabited 
by a different stock of that same species, yet are 
still within their native range; and genetically 
compatible introductions, in which fish are 
removed from a given water body and they, or 
more often their offspring, are introduced back 
into that water body or another water body that 
is still within the boundaries of the genetic stock 
serving as the hatchery brood source (Philipp et 
al. 1993). 

Although non-native introductions may 
often cause ecological problems for the envi- 
ronments in which they are introduced, they can 
also cause genetic problems if they hybridize 
with closely related native species. Examples of 
this are the hybridization of introduced small- 
mouth bass (Micropterus dolomieu) and spotted 
bass (M. punctulatus) with native Guadalupe 
bass (M. treculi) in Texas (Morizot et al. 1991), 
and the hybridization of introduced rainbow 
trout {Oncorhynchus mykiss) with native 
Apache trout (O. apache; Carmichael et al. 
1993). The greatest degree of genetic damage, 
that is, the loss of genetic variation among pop- 
ulations, is caused by stock transfers, a common 



Loss of 

Genetic 

Diversity 

Among 

Managed 

Populations 



by 

David P. Philipp 

Julie E. Claussen 

Illinois Natural History 

Survey 



14H 



Fishes — Our Living Resources 



- Native range 
] FL subspecies 



■ Hybrid subspecies 
□ North, subspecies 




Figure. Loss of genetic variation 
among largemouth bass popula- 
tions, a. The native range of the 
largemouth bass (Micropterus 
salnwides) is delineated by the red 
lines (MacCrimmon and Robbins 
1975). As first described by Bailey 
and Hubbs (1949), the Florida sub- 
species. M.S. floridanus, was 
restricted to peninsular Florida 
(blue); the northern subspecies, 
M.s. salnwides, covered most of the 
rest of the range of the species; and 
there was a relatively small inter- 
grade zone between the two result- 
ing from some indeterminable com- 
bination of natural hybridization 
and human-caused mixing of 
stocks, b. The expansion of the 
intergrade by 1980 was described 
by Philipp et al. (1983). Because 
detailed ranges were not explored 
in all states, and because this inter- 
grade zone expansion was likely 
caused by state stocking programs, 
entire states are classified according 
to whether the intergrade zone was 
expanded, c. The current intergrade 
zone is now even larger because of 
the addition of more states in which 
largemouth bass containing at least 
some M.s. floridanus genes are 
being introduced either by the state 
fish and game agencies themselves 
or by private groups. Notice that the 
(.-lit ire southern and eastern portion 
of the original range of the northern 
subspecies, M.s. salmoides. is at 
risk of being inundated with M.s. 
floridanus genes. 



practice among fisheries management agencies 
and the private sector. 

Largemouth Bass 

Largemouth bass (Micropterus salmoides) 
exemplify how introduction programs cause the 
loss of genetic diversity. The original range of 
the largemouth bass was restricted to parts of 
the central and southeastern United States 
(Figure), extending northward into some of 
southern Ontario (MacCrimmon and Robbins 
1975). Bailey and Hubbs (1949), however, 
described two subspecies. The Florida sub- 
species, M.s. floridanus, was formerly restricted 
to much of peninsular Florida (Figure, a), 
whereas the range of the northern subspecies, 
M.s. salmoides, extended north and west of an 
intergrade zone that included parts of South 
Carolina, Georgia, Alabama, and northern 
Florida. It is likely, though, that the intergrade 
zone had already been expanded from the orig- 
inal natural hybrid zone as a result of early fish 
stocking programs. 

Since 1949, however, much more serious 
stocking efforts have extended this intergrade 
zone. A survey of largemouth bass populations 
conducted in the late 1970's (Philipp et al. 
1983) revealed that the intergrade zone had 
grown considerably larger through the deliber- 
ate stocking efforts of the involved state agen- 
cies (Figure, b). Additional introductions of 
M.s. floridanus since that genetic survey have 
now spread the genes of that subspecies across 
the entire southern range of M.s. salmoides 
(Figure, c). 

This introduction of the Florida largemouth 
has compromised the genetic integrity of all the 
populations of the northern largemouth bass 
into which the species has been introduced 
(populations in Texas, Oklahoma, Arkansas, 
Louisiana, Mississippi, Tennessee, Alabama, 
Georgia, South Carolina, North Carolina. 
Virginia, and Maryland, at a minimum). Those 
now-genetically mixed populations have lost 
much of their distinctness because of the loss of 
among-population genetic variation that accom- 
panies this type of homogenization. Populations 
other than those in the water bodies actually 
stocked will be affected as well because of 
inevitable gene flow into and between other 
connected populations. As a result, genetic 
integrity is now at risk for all populations of this 
important sportfish species throughout the 
southern and eastern portions of its native 
range. 

In addition, because the two subspecies have 
quite different characteristics (Cichra et al. 
1982; Fields et al. 1987; Kleinsasser et al. 
1990), these massive stock transfers will likely 
result in outbreeding depression. More specifi- 



cally, the Florida subspecies exhibits signifi- 
cantly poorer survival, growth, and reproductive 
success in Illinois than does the northern sub- 
species (Philipp 1991; Philipp and Whitt 1991). 
Also, the offspring resulting from crossing the 
two subspecies (in either direction) are less fit 
in Illinois than are the offspring of the pure 
northern subspecies (Philipp 1991). These 
results extend to populations of the northern 
subspecies across its range from Texas to 
Minnesota (unpublished data). 

Conclusions 

The genetic integrity of largemouth bass 
stocks, and likely of many other managed fish 
species as well, is eroding as a result of man- 
agement programs that inadvertently permit or 
deliberately promote stock transfers. This caus- 
es not only the loss of genetic variation among 
populations, but through outbreeding depres- 
sion it is also probably negatively affecting the 
fitness of many native stocks involved. We need 
to address genetic integrity when restoring 
native populations. 

References 

Allendorf, F.W., N. Ryman, and F.M. Utter. 1987. Genetics 
and fishery management past, present, and future. Pages 
1-19 in N. Ryman and F.M. Utter, eds. Population genet- 
ics and fishery management. Washington Sea Grant 
Program, Seattle. 

Altukhov, Y.P., and E.A. Salmenkova. 1987. Stock transfer 
relative to natural organization, management and conser- 
vation of fish populations. Pages 333-344 in N. Ryman 
and F.M. Utter, eds. Population genetics and fishery man- 
agement. Washington Sea Grant Program. Seattle. 

Bailey. R.M.. and C.L. Hubbs. 1949. The black basses 
[Micropterus) of Florida, with description of a new 
species. University of Michigan Museum of Zoology 
Occasional Papers 516:1-40. 

Campton, D.E. 1987. Natural hybridization and introgres- 
sion in fishes; methods of detection and interpretation. 
Pages 161-192 in N. Ryman and F.M. Utter, eds. 
Population genetics and fishery management. 
Washington Sea Grant Program. Seattle. 

Carmichael, G.J., J.N. Hanson, M.E. Schmidt, and D.C. 
Morizot. 1993. Introgression among Apache, cutthroat, 
and rainbow trout in Arizona. Transactions of the 
American Fisheries Society 122:121-130. 

Cichra, C.E., W.H. Neill, and R.L. Noble. 1982. Differentia] 
resistance of northern and Florida largemouth bass to 
cold shock. Proceedings of the Southeastern Association 
of Fish and Wildlife Agencies 34( 1980): 19-24. 

Fields, R., S.S. Lowe, C. Kaminski, G.S. Whitt, and D.P. 
Philipp. 1987. Critical and chronic thermal maxima of 
northern and Florida largemouth bass and their recipro- 
cal F, and F-, hybrids. Transactions of the American 
Fisheries Society 1 16:856-863. 

Kleinsasser. L.J.. J.H. Williamson, and B.G. Whiteside. 
1990. Growth and catchability of northern Florida and F, 
hybrid largemouth bass in Texas ponds. North American 
Journal of Fisheries Management 10:462-468. 

Kutkuhn, J.H. 1981. Stock definition as a necessary basis 
for cooperative management of Great Lakes fish 
resources. Canadian Journal of Fisheries and Aquatic 
Sciences 38:1476-1478. 

MacCrimmon, H.R., and W.H. Robbins. 1975. Distribution 
of the black basses in North America. Pages 56-66 in 



Our Living Resources — Fishes 



149 



R.H. Stroud and H. Clepper. eds. Black bass biology and 
management. Sport Fishing Institute, Washington, DC. 

Morizot, D.C., S.W. Calhoun, L.L. Clepper, M.E. Schmidt, 
J.H. Williamson, and G.J. Carmichael. 1991. 
Multispecies hybridization among native and introduced 
centrarchid basses in central Texas. Transactions of the 
American Fisheries Society 120:283-289. 

Philipp. D.P. 1991. Genetic implications of introducing 
Florida largemouth bass, Micropterus salmoides flori- 
danus. Canadian Journal of Fisheries and Aquatic- 
Sciences 48( 1 ):58-65. 

Philipp, D.P., W.F. Childers, and G.S. Whitt. 1983. A bio- 
chemical genetic evaluation of the northern and Florida 
subspecies of largemouth bass. Transactions of the 
American Fisheries Society 1 12:1-20. 

Philipp, D.P, J.M. Epifanio, and M.J. Jennings. 1993. 
Conservation genetics and current stocking practices: are 
they compatible? Fisheries 18:14-16. 



Philipp, DP, and G.S. Whitt. 1991. Survival and growth of 
northern, Florida, and reciprocal Fj hybrid largemouth 
bass in central Illinois. Transactions of the American 
Fisheries Society 120:156-178. 

Soule, M.E., ed. 1987. Conservation biology: the science of 
scarcity and diversity. Sinauer Associates, Inc., 
Sunderland, MA. 584 pp. 

Templeton, A.R. 1987. Coadaptation and outbreeding 
depression. Pages 105-116 in M.E. Soule, ed. 
Conservation biology: the science of scarcity and diver- 
sity. Sinauer Associates, Inc., Sunderland, MA. 

Wright, S. 1931. Evolution in Mendelian populations. 
Genetics 16:97-159. 

Wright, S. 1978. Evolution and the genetics of populations. 
Vol. 4. Variability within and among natural populations. 
University of Chicago Press, IL. 



For further information: 

David P. Philipp 

Illinois Natural History Survey 

Center for Aquatic Ecology 

607 E. Peabody Dr. 

Champaign, IL 61820 



The Colorado River and its tributaries have 
undergone drastic alterations from their nat- 
ural states over the past 125 years. These alter- 
ations include both physical change or elimina- 
tion of aquatic habitats and the introductions of 
numerous non-native species, particularly fish. 
Ironically, several more species occur at most 
localities today than were historically present 
before these alterations. This situation compli- 
cates the use of biodiversity as a litmus test for 
monitoring trends of either the deterioration or 
the health of an aquatic ecosystem. 

An Altered Ecosystem 

Over its entire basin (Figure), the Colorado 
River has been changed from its natural state 
perhaps as much as any river system in the 
world. The demands for water and power in the 
arid West have drastically altered the system by 
impoundments, irrigation diversions, diking, 
channelization, pollutants, and destruction of 
bank habitats by cattle grazing and other prac- 
tices. Some reaches, ranging from desert spring 
runs to main rivers, have been completely dewa- 
tered or, seasonally, their flows consist almost 
entirely of irrigation return laden with silt and 
chemical pollutants. The Gila River of Arizona, 
one of the Colorado's largest tributaries, has not 




Captive bonytail (Gila elegans), rarest of the larger river 
species in the Colorado River Basin. 



flowed over its lower 400 km (248 mi) since the 
early 1900's. These alterations and their effects 
on the fish fauna have been discussed by sever- 
al authors (Miller 1961; Minckley and Deacon 
1968; Stalnaker and Holden 1973; Carlson and 
Muth 1989; Minckley and Deacon 1991). Only 
a few small tributaries, mostly at higher eleva- 
tions, retain most of their natural characteris- 
tics. 

Native Fish Fauna 

Despite the expansive drainage basin 
(631,960 km 2 [243,937 mi 2 ]) of the Colorado 
River, the system supported only a relatively 
small number of native fish species compared 
with basins of much smaller size east of the 
Continental Divide. The Colorado Basin's 
native fauna, however, was nearly unique. If 
two former marine invaders are removed from 
the 51 native taxa known from the system 
(Table 1 ), 42 of the 49 that remain (86%) are 
considered endemic to the system. The greatest 
diversity of taxa (44) was distributed in the 
Lower Basin downstream of the Arizona-Utah 
border, in a variety of habitats that include 
mainstem rivers, smaller tributaries, and isolat- 
ed springs. The Upper Basin was much less 
diverse, containing 14 species, including a sub- 
set of the Lower Basin fauna plus 4 headwater 
species that occur in cooler water and a warm 
spring endemic. Basinwide, about 5 species 
occurred mostly in mainstem river or larger trib- 
utary habitats, 37 were restricted to smaller, in 
some cases isolated, habitats, and 7 were more 
generally distributed among different habitat 
types. 

Trends 

As a consequence of habitat alterations, the 
prevailing trend among native fish populations 
in the Colorado River Basin has been drastic 



Colorado 
River Basin 
Fishes 



by 

Wayne C. Starnes 
Smithsonian Institution 



150 



Fishes — Our Living Resources 




x Dams 



Figure. Colorado River Basin. 



reductions that include decreased abundance in 
all or part of their ranges, overall range reduc- 
tions, or virtual or actual extinctions (Tables 1 
and 2). Presently, 40 of the 49 strictly freshwa- 
ter, native species are considered either possibly 
or actually jeopardized or are extinct (Table 1). 
Of the 40, 1 2 are of special concern. 25 are con- 
sidered endangered or threatened, and 3 are 
believed extinct. 

In the Lower Basin, only 3 of the 10 native 
species that inhabited the mainstem of the lower 
Colorado River remained by the 1940's but by 
the 1960's, none remained. In the lower Salt 
River portion of the Gila River system, the orig- 
inal complement of 14 taxa was also reduced to 
3 by the 1940's and to 2 by the 1960's; today, 
they are probably extirpated. In the early 
1900's, the isolated springs of the Pluvial White 
River system in southern Nevada harbored 17 
endemic taxa; today, 1 of those taxa is extinct, 9 
endangered, 3 threatened, and the remainder of 



Table 1. Native fish taxa of the Colorado River Basin 
including currently recognized subspecies. Taxa denoted 
by * may eventually prove genetically distinct from popu- 
lations outside the Colorado River Basin. Those denoted 
"(m)" are marine invaders. Status of jeopardized and 
extinct species appears in parentheses: E = endangered; 
T = threatened; SC = special concern; X = extinct (based. 
in part, on Carlson and Muth 1989; Williams et al. 1989; 
and the National Biological Service's Category 2 list). 
Common names bracketed with quotation marks indicate 
that those species are undescribed and not officially 
named. 



Scientific name 


Common name 


Family Elopidae 


Elops affinis (m) 


Machete 


Family Cyprinidae 


Agosia chrysogaster 


Longfin dace 


Gilacypha (E) 


Humpback chub 


67. elegans (E) 


Bonytail 


G. intermedia (SC) 


Gila chub 


G. robusta jordani (E) 


Pahranagat chub 


G. robusta robusta (SC) 


Roundtail chub 


G. seminuda (E) 


Virgin chub 


Lepidomeda albivallis (E) 


White River spinedace 


L a/Ms (X) 


Pahranagat spinedace 


L mollispinis mollispinis (T) 


Virgin spinedace 


Lm. pratensis (E) 


Big Spring spinedace 


L vittata (T) 


Little Colorado spinedace 


Meda fulgida (T) 


Spikedace 


Moapa coriacea (E) 


Moapa dace 


Plagopterus argentissimus (E) 


Woundfin 


Ptychocheilus lucius (E) 


Colorado squawfish 


Rhinichthys cobitis (T) 


Loach minnow 


ft deaconi (X) 


Las Vegas dace 


ft osculus osculus 


Speckled dace 


ft osculus ssp.(SC) 


"Preston speckled dace" 


ft osculus ssp. (SC) 


"Meadow Valleys speckled dace" 


ft osculus ssp. (SC) 


"White River speckled dace" 


fto. thermalis (SC) 


Kendall Warm Springs dace 


R.o. velifer (SC) 


Pahranagat speckled dace 


Family Catostomidae 


Catostomus clarki clarki 


Desert sucker 


C.c. intermedius (E) 


White River sucker 


C. clarki ssp. (E) 


"Meadow Valley sucker" 


C discobolus discobolus 


Bluehead sucker 


C.d. yarrowi (SC) 


Zuni sucker 


C. insignis 


Sonora sucker 


C. latipinnis (SC) 


Flannelmouth sucker 


C. platyrhynchus 


Mountain sucker 


C. sp.(SC) 


"Little Colorado sucker" 


Xyrauchen texanus (E) 


Razorback sucker 


Family Salmonidae 


Oncorhynchus apache (T) 


Apache trout 


0. clarki pleuriticus (SC) 


Colorado cutthroat trout 


0. gilae (T) 


Gila trout 


Prosopium Williamson! ' 


Mountain whitefish 


Family Goodeidae 


Crenichthys baileyi albivallis (E) 


Preston springfish 


C.b. baileyi (E) 


White River springfish 


C.b. grandis (E) 


Hiko springfish 


C.b. moapae (T) 


Moapa springfish 


C.b. thermophilus (T) 


Moorman springfish 


C nevadae (T) 


Railroad Valley springfish 


Family Cyprinodontidae 


Cyprinodon macularius macularius 


(E) Desert pupfish 


C sp. (X) 


"Monkey Springs pupfish" 


Family Poeciliidae 


Poeciliopsis occidentalis (SC) 


Gila topminnow 


Family Cottidae 


Cottus bairdi' 


Mottled sculpin 


C. beldingi' 


Paiute sculpin 


Family Mugilidae 


Mugil cephalus (m) 


Striped mullet 



Our Living Resources — Fishes 



151 



special concern. On the other hand, a few small 
tributaries, by virtue of their isolation, rare 
intermittent flows in lower reaches, and physi- 
cal barriers, have been spared significant alter- 
ations or invasions by non-native species and 
retain an intact native fauna (e.g., Redfield 
Canyon, Arizona, Table 2). 

In the larger rivers of the Upper Basin, such 
as the Green, lower Yampa, and most of the 
upper Colorado, most native taxa are extant but 
one or two (razorback sucker [Xyrauchen tex- 
anus], possibly bony tail [Gila elegans]), are re- 
presented by very rare individuals that may not 
be reproducing; all native fishes are greatly 
exceeded in numbers and kind by non-native 
taxa. In smaller tributaries of that region, varied 
numbers of native taxa persist; in the worst 
affected streams (e.g.. most Green River tribu- 
taries in Utah), most taxa have been replaced by 
non-native taxa (author's observation). 

Case studies of two endangered Colorado 
River species, which are hallmarks to conserva- 
tionists, further elucidate patterns of decline 
among these fishes. They are large, long-lived 
(20-50 years) species that inhabit larger 
streams. The Colorado squawfish (Ptycho- 
cheilus lucius) is a highly migratory (Tyus 
1990) predatory minnow. Perhaps because of 
fragmentation or impediment of migratory 
routes, its original extensive range has been 
reduced by roughly two-thirds, and it is uncom- 
mon where it remains. The last confirmed report 
in the Gila River was in 1950 and the last in the 
Lower Basin in 1975 (Miller 1961; Minckley 
1973; Maddux et al. 1993). 

The fourth species, the humpback chub 
(Gila cypha), is strictly a denizen of turbulent 
canyon reaches so difficult to sample that it was 
not discovered until 1946; it ranged from 
Boulder Canyon on the lower Colorado 
throughout canyon reaches of the Upper Basin 
well into Wyoming. Today, it occurs only in 
Grand Canyon, Arizona (Maddux et al. 1993), 
near the confluence of the Colorado and Little 
Colorado rivers, and in five Upper Basin canyon 
areas (rare in three), although the genetic "puri- 
ty" of the Upper Basin populations is ques- 
tioned. Recovery plans are in place for these 
fish as well as the bonytail and the razorback 
sucker. These fish are all easily propagated in 
captivity. It is otherwise difficult to find any- 
thing positive in the history of these or other 
Colorado Basin native fishes over the past sev- 
eral decades. 

Non-native Species 

Concomitant with the pervasive physical 
alteration of the Colorado River ecosystem has 
been both purposeful and accidental introduc- 
tions of at least 72 non-native fish taxa (Maddux 



et al. 1993), including those indigenous to other 
North American basins and more exotic species. 
Alterations of the ecosystem's natural charac- 
teristics have apparently tipped the ecologic 
balance in favor of many of the non-native 
species that now vastly outnumber natives in 
numbers of species (Table 2), population densi- 
ty, and often biomass at most localities. There is 
evidence that some, such as the extremely per- 
vasive red shiner (Cyprinella lutrensis), dis- 
place native taxa (Douglas et al. 1994) while 
others, such as channel and flathead catfish 
(Ictalurus punctatus and Pylodictis olivaris), 
are known predators on larval and juvenile 
native species (several references in Maddux et 
al. 1993). The introduced white sucker 
(Catostomus commersoni) is hybridizing exten- 
sively with native suckers throughout much of 
the Upper Basin (author's observation), possi- 
bly threatening the genetic integrity of those 
taxa. These and other interactions between non- 
native and native taxa may have significant neg- 
ative effects on native fishes. The dominance 
held by non-native fishes may be symptomatic 
of the overall degree of alteration of the 
Colorado River ecosystem and could potential- 
ly confound future studies of biodiversity. 



Table 2. Overall and relative 
abundance of native and non- 
native fishes from various locali- 
ties in the Colorado River Basin. 
Numbers for 1 800's represent 
original complements of native 
taxa. For subsequent years, total 
abundance is followed by ratio of 
non-native to native taxa in paren- 
theses. Sources: Miller 1961; 
Taba et al. 1965; Vanicek et al. 
1970; Stalnakerand Holden 1973; 
Cross 1975; Holden and Stalnaker 
1975a,b;Suttkusetal. 1976; 
Carlson et al. 1979; Miller et al. 
1982; Valdez et al. 1982; Valdez 
1984,1990; Wick et al. 1985; 
Platania and Bestgen 1988; 
Griffith and Tiersch 1989. 



Localitv Survey date 


Lui/ditiy 


1800's 


1940's 


ea. 1965 


ca. 1975 


ca.1985 


Yampa-Green River area, CO-UT 


10 




21(12/9) 


22(13/9) 


24(15/9) 


White River, CO-UT 


9 


- 


- 


13(7/6) 


12(5/7) 


Dolores River, CO 


9 


- 




11(7/4) 


16(12/4) 


Colorado River, Lake Powell, UT to Gunnison River, CO 


10 


- 


15(9/6) 


29(19/10) 


31(23/8) 


San Juan River, NM 


9 


- 






18(12/6) 


Colorado River, Grand Canyon, AZ 


10 


- 


- 


19(15/4) 


" 


Virgin River, AZ-UT 


6 






19(13/6) 


- 


Lower Colorado River, AZ-CA 


10 


12(9/3) 


11(11/0) 


- 


. 


Salt River near Phoenix, AZ 


14 


9(6/3) 


22(?0/2) 




- 


Redfield Canyon, San Pedro River system, AZ 


5 








5(0/5) 



Altered Species Diversity and 
Biodiversity Studies 

While native taxa have declined, there have 
actually been two- to threefold increases in the 
number of species at most localities in the 
Colorado Basin because of the success of intro- 
duced taxa (Table 2). If future biodiversity mon- 
itoring is to truly gauge positive and negative 
shifts in the health of the Colorado River 
ecosystems, then an accurate baseline is neces- 
sary. A baseline describing unaltered native 
fauna might be an ideal but unattainable goal. 
That line could be approached, however, by 
divesting faunal lists of all non-native taxa and 
determining, as much as possible, the true 
extent of diversity of that which remains. In 
fish, it is practical to do so to the level of dis- 
tinctive populations through studies of genetic 
variability. With luck, it is even possible to 



152 



Fishes — Our Living Resources 



For further information: 

Wayne C. Starnes 

Smithsonian Institution 

Division of Fishes MRC 159 

Washington. DC 20560 



include extirpated populations through DNA 
studies of museum specimens if historic mater- 
ial is available. 

Once a baseline is determined, researchers 
and managers can know where to try to "hold 
the line" in maintaining diversity through man- 
agement and protection. Of course, on a sys- 
temwide basis, the baseline diversity of a pris- 
tine system can never be reattained because 
genetically unique populations have already 
been lost. On a more local basis, however, pos- 
itive increments and recovery of the habitat are 
indicated if monitoring reveals increased diver- 
sity resulting from the successful reestablish- 
ment of taxa which were conserved in other, 
less altered, portions of the system. 

For monitoring purposes, when non-native 
species are added to biodiversity determina- 
tions, we must carefully tease out the cause of 
shifts toward or from the "desired baseline" 
which, in the case of the Colorado River, is 
probably a value far less than the present over- 
all number of species. Thus, "desirable" out- 
comes may be indicated by overall decreases in 
diversity caused by the disappearance of non- 
native taxa as an indicator of habitat "healing," 
but not so by the loss of native taxa. 
Conversely, actual increases may yet be positive 
if caused by reestablishment of native taxa, but 
may be an indicator of further degradation if 
caused by success of additional non-natives. 
Realistically, monitoring will have to include, in 
addition to determinations of diversity, attention 
to shifts in dominance among native and non- 
native species, which can be indicative of both 
positive and negative trends. 

References 

Carlson, C.A., and R. Muth. 1989. The Colorado River: life- 
line of the West. Pages 220-239 in D.P. Dodge, ed. 
Proceedings of the International Large River Symposium. 
Canadian Special Publ. in Fishery and Aquatic Sciences 
106. 

Carlson, C.A., C.G. Prewitt. D.E. Snyder, and E.J. Wick. 
1979. Fishes and macroinvertebrates of the White and 
Yampa rivers, Colorado. Bureau of Land Management, 
Biological Sciences Series 1. Denver, CO. 276 pp. 

Cross, J.N. 1975. Ecological distribution of the fishes of the 
Virgin River. M.S. thesis, University of Nevada, Las 
Vegas. 1 87 pp. 

Douglas, M.E.. PC. Marsh, and W.L. Minckley. 1994. 
Indigenous fishes of western North America and the 
hypothesis of competitive displacement: Meda fulgida 
(Cyprinidae) as a case study. Copeia 1994:9-19. 

Griffith. J.S.. and T.R. Tiersch. 1989. Ecology of fishes in 
Redfield Canyon, Arizona, with emphasis on Gila robusta 
intermedia. Southwestern Naturalist 34:131-164. 

Holden, P.B., and C.B. Stalnaker. 1975a. Distribution of fish- 
es in the Dolores and Yampa river systems of the Upper 
Colorado Basin. Southwestern Naturalist 19:403-412. 



Holden, P.B., and C.B. Stalnaker. 1975b. Distribution and 
abundance of mainstream fishes of the Middle and Upper 
Colorado River basins. 1967-1973. Transactions of the 
American Fisheries Society 104:217-231. 

Maddux, H.R., L.A. Fitzpatrick, and W.R. Noonan. 1993. 
Colorado River endangered fishes critical habitat draft 
biological support document. U.S. Fish and Wildlife 
Service, Salt Lake City, UT. 225 pp. 

Miller, R.R. 1961. Man and the changing fish fauna of the 
American Southwest. Papers of the Michigan Academy of 
Science, Arts, and Letters 46:365-404. 

Miller, W.H., D. Archer, H.M. Tyus, and R.M. McNatt. 1982. 
Yampa River fishes study, final report. Colorado River 
Fishery Project. U.S. Fish and Wildlife Service. Salt Lake 
City, UT. 79 pp. 

Minckley, W.L. 1973. Fishes of Arizona. Arizona Game and 
Fish Department. Phoenix. 293 pp. 

Minckley, W.L., and J.E. Deacon. 1968. Southwestern fishes 
and the enigma of endangered species. Science 
159:1424-1432. 

Minckley. W.L., and J.E. Deacon, eds. 1991. Battle against 
extinction: native fish management in the American West. 
University of Arizona Press, Tucson. 517 pp. 

Platania, S.P, and K.R. Bestgen. 1988. An interim report on 
the fishes of the lower San Juan River. New Mexico. 1987. 
New Mexico Department of Game and Fish. Santa Fe. 61 
pp. 

Stalnaker, C.B., and PB. Holden. 1973. Changes in native 
fish distribution in the Green River system. Utah- 
Colorado. Utah Academy of Science. Arts, Letters 
Proceedings 50:25-32. 

Suttkus, R.D.. G.H. Clemmer, C. Jones, and C.R. Shoop. 
1976. Survey of fishes, mammals and herpetofauna of the 
Colorado River and adjacent riparian areas of the Grand 
Canyon National Park. Grand Canyon National Park 
Colorado River Research Serial Contribution 34. 48 pp. 

Taba, S.S., J.R. Murphy, and H.R. Frost. 1965. Notes on the 
fishes of the Colorado River near Moab, Utah. Utah 
Academy of Science, Arts. Letters Proceedings 42:280- 
283. 

Tyus. H.M. 1990. Potamodromy and reproduction of 
Colorado River squawfish (Ptychocheilus lucius). 
Transactions of the American Fisheries Society 1 19:1035- 
1047. 

Valdez. R. 1984. A survey of fish collections in the White 
River, Utah. Report for White River Shale Corporation, 
Ecosystem Research Institute, Logan. UT. 39 pp. 

Valdez. R. 1990. The endangered fish of Cataract Canyon. 
Bio/West Report 134-3 for Bureau of Reclamation. Salt 
Lake City. UT. 94 pp. 

Valdez. R.. P. Mangan, M. Mclnemy, and R.P Smith. 1982. 
Tributary report: fishery investigations of the Gunnison 
and Dolores rivers. Pages 322-365 in Colorado River 
Fisheries Project Final Report of Field Investigations. Part 
2. U.S. Fish and Wildlife Service, Salt Lake City, UT. 

Vanicek, CD.. R.H. Kramer, and D.R. Franklin. 1970. 
Distribution of Green River fishes in Utah and Colorado 
following closure of Flaming Gorge Dam. Southwestern 
Naturalist 14:297-315. 

Wick, E.J., J.A. Hawkins, and C.A. Carlson. 1985. Colorado 
squawfish and humpback chub habitat monitoring. 1981- 
1982. Colorado State University Larval Fish Lab and 
Colorado Division of Wildlife Rep. SE 3-6. 41 pp. 

Williams, J.E.. J.E. Johnson. D.A. Hendrickson. S. 
Contreras-Balderas. J.D. Williams. M. Navarro- 
Mendoza, D.E. McAllister, and J.E. Deacon. 1989. Fishes 
of North America endangered, threatened, or of special 
concern: 1989. Fisheries 14:2-80. 



Our Living Resources — Fishes 



153 



The indigenous fishery of Glacier National 
Park has been radically altered from its pris- 
tine condition during the past half-century 
through introductions of non-native fishes and 
the entry of non-native species from waters out- 
side the park. These introductions have adverse- 
ly affected the native westslope cutthroat trout 
{Oncorhynchus clarki lewisi; Fig. 1) throughout 
much of its park range. 

The effects of non-native fishes on indige- 
nous fisheries have been reviewed by Taylor et 
al. (1984), Marnell (1986), and Moyle et al. 
(1986). Effects of fish introductions in Glacier 
National Park include establishment of non- 
native trout populations in historically Ashless 
waters, genetic contamination (i.e., hybridiza- 
tion) of some native westslope cutthroat trout 
stocks, and ecological interferences with vari- 
ous life-history stages of native trout. 

Research conducted in the park during the 
1980's addressed the genetic effects of fish 
introductions on native trout. Of 47 lakes 
known or suspected to contain cutthroat trout or 
trout hybrids, 32 lakes contained viable popula- 
tions of cutthroat trout, rainbow trout (O. 
mykiss), or hybrids. Trout introduced in the 
other waters were evidently unable to sustain 
themselves through natural reproduction. 




Fig. 1. Westslope cutthroat trout (Oncorhynchus clarki 
lewisi). 




Fig. 2. Yellowstone cutthroat trout (Oncorhynchus clarki 
bouvieri). 

About 30 trout sampled from each lake 
underwent laboratory genetic analyses. Close 
agreement of the results from two analytical 
procedures yielded a high degree of confidence 
in the conclusions (Marnell et al. 1987). Genetic 
classifications in Tables 1 and 2 reflect the com- 
bined results of the analyses. 

Fourteen pure strain populations of west- 
slope cutthroat trout persist in 15 lakes (i.e., 
some interconnected lakes contain a single trout 
population) in the North and Middle Fork 
drainages of the Flathead River; the species was 
historically present in these waters (labeled as 
"stable" populations in Table 1). 

Pure strain native trout also inhabit four 



other Middle Fork lakes (i.e., Avalanche, 
Snyder, and Upper and Lower Howe lakes), but 
it is unclear whether they are indigenous or 
were transplanted from other park waters. 
Recent findings from sediment paleolimnology 
studies suggest that trout have been present in at 
least one of these lakes for more than 300 years 
(D. Verschuren, University of Minnesota, and 
author, unpublished data). Hence, trout popula- 
tions in these four lakes are tentatively classi- 
fied as indigenous (Table 1 ). 

Introduced populations of Yellowstone cut- 
throat trout (O. clarki bouvieri; Fig. 2) and trout 
hybrids including cutthroat-rainbow trout (O. 
clarki spp. x O. mykiss) occur in 13 lakes dis- 
tributed among the three continental drainages 



Lake 


Area (ha) 


Trout 
classification* 


Population 
status" 


North Fork, Flathead R. 


Akokala 


9 


WCT 


Stable 


Arrow 


23 


WCT x YCT 


Hybrid 


Bowman 


691 


WCT 


Unstable 


Camas 


8 


YCT 


Non-native 


Cerulean 


20 


WCT 


Stable 


Evangeline 


28 


YCT 


Non-native 


Grace 


32 


WCT x YCT 


Hybrid 


Kintla 


688 


WCT 


Unstable 


Logging 


444 


WCT 


Unstable 


Quartz 


349 


WCT 


Stable 


Lower Quartz 


67 


WCT 


Stable 


Middle Quartz 


19 


WCT 


Stable 


Trout 


86 


WCT 


Stable 


Middle Fork, 1 


: lathead R. 






Avalanche 


23 


WCT 


Stable 


Fish 


3 


WCT x YCT 


Hybrid 


Harrison 


101 


WCT 


Unknown 


Hidden 


110 


YCT 


Non-native 


Lincoln 


14 


WCT 


Stable 


Lower Howe 


12 


WCT 


Stable 


Lower Isabel 


17 


WCT 


Stable 


McDonald 


2,760 


WCT 


Unstable 


Ole 


2 


WCT 


Stable 


Snyder 


2 


WCT 


Stable 


Upper Howe 


3 


WCT 


Stable 


Upper Isabel 


6 


WCT 


Stable 



: WCT — pure strain westslope cutthroat trout. 
YCT — the introduced Yellowstone cutthroat trout, 
x — two or more species have hybridized. 

'Stable — native population exists in a pristine environment. 
Unstable — declining condition resulting from presence of competing 
non-native species. 

Hybrid and non-native populations — classified without regard to popu- 
lation condition. 



Lake 


Area (ha) 


Trout 
classification* 


Population 
status" 


South Saskatchewan River 


Lower Slide 


15 


YCT x RBT 


Hybrid 


Otokomi 


9 


YCT x RBT 


Hybrid 


Red Eagle 


55 


YCT x WCT x RBT 


Hybrid 


Upper Slide 


5 


YCT x RBT 


Hybrid 


Upper Missouri River Drainage 


Katoya 


4 


YCT 


Non-native 


Morning Star 


4 


YCT 


Non-native 


Old Man 


17 


YCT 


Non-native 



"YCT— introduced Yellowstone cutthroat trout, 
x — two or more species have hybridized. 
RBT— rainbow trout. 
WCT — westslope cutthroat trout. 

"Hybrid and non-native populations are classified without regard to popu- 
lation condition. 



Cutthroat 
Trout in 
Glacier 
National Park, 
Montana 

by 
Leo F. Marnell 

National Biological Service 



Table 1. Status and trends of cut- 
throat trout and their hybrids in the 
North and Middle Fork, Flathead 
River drainages of Glacier 
National Park, Montana. 



Table 2. Status and trends of non- 
native and hybrid trout populations 
in the South Saskatchewan and 
Missouri river drainages of Glacier 
National Park. Montana. 



154 



Fishes — Our Living Resources 



For further information: 

Leo F. Marnell 

National Biological Service 

Midcontinent Ecological Science 

Center 

Glacier Field Station 

Glacier National Park 

West Glacier, MT 59936 



that form their headwaters in Glacier National 
Park (Tables 1 and 2). Native cutthroat trout 
were not found east of the Continental Divide in 
the Missouri River or South Saskatchewan 
River drainages within the park. 

In addition to genetic concerns, ecological 
disturbances associated with the presence of 
introduced fishes have compromised the native 
westslope cutthroat fishery. Fish are no longer 
stocked in park waters; however, several waters, 
including some that contain undisturbed native 
fisheries, remain vulnerable to invasion by non- 
native migratory species. Introduced kokanee 
salmon (O. nerka), a specialized planktivore, 
are believed to be competing with juvenile 
stages of native trout in some waters, especially 
during periods of winter ice cover when plank- 
ton may be limited. Predation by introduced 
lake trout (Salvelinus namaycush) has also been 
implicated in the decline of native cutthroat 
trout in several large glacial lakes in the North 
and Middle Fork drainages (Marnell 1988). 
Native cutthroat trout have been compromised 
by fish introductions and invasions throughout 
about 84% of their historic range in Glacier 
National Park (Marnell 1988). 

Although native cutthroat trout have been 
adversely affected throughout a large portion of 
their park range, the species has not been lost 



from any water where it was historically pre- 
sent. Glacier National Park remains one of the 
last strongholds of genetically pure strains of 
lacustrine (i.e., lake-adapted) westslope cut- 
throat trout. This fact could have important 
implications for reestablishment of this unique 
subspecies throughout the central Rocky 
Mountains, where this trout has disappeared 
from most of its original range. 

References 

Marnell, L.F 1986. Impacts of hatchery stocks on wild fish 
populations. Pages 339-347 in R.H. Stroud, ed. Fish cul- 
ture in fisheries management. American Fisheries 
Society, Bethesda, MD. 

Marnell, L.F. 1988. Status of the westslope cutthroat trout in 
Glacier National Park, Montana. American Fisheries 
Society Symposium 4:61-70. Bethesda. MD. 

Marnell, L.F, R.J. Behnke, and FW. Allendorf. 1987. 
Genetic identification of cutthroat trout (Salmo clarki) in 
Glacier National Park, Montana. Canadian Journal of 
Fisheries and Aquatic Sciences 44:1830-1839. 

Moyle. P.B., H. Li. and B.A. Barton. 1986. The 
Frankenstein effect: impact of introduced fishes in North 
America. Pages 415-426 in R.H. Stroud, ed. Fish culture 
in fisheries management. American Fisheries Society. 
Bethesda, MD. 

Taylor, J.N., W.R. Courtenay, Jr., and J. A. McCann. 1984. 
Known impacts of exotic fishes in the continental United 
States. Pages 322-373 in W.R. Courtenay, Jr., and J.R. 
Stauffer, eds. Distribution, biology, and management of 
exotic fishes. Johns Hopkins University Press. Baltimore. 
MD. 



Columbia 
River Basin 
White 
Sturgeon 

by 

Allen I. Miller 

Timothy D. Counihan 

Michael J. Parsley 

Lance G. Beckman 

National Biological Service 



White sturgeon (Acipenser transmontanus), 
the largest freshwater fish in North 
America, live along the west coast from the 
Aleutian Islands to central California (Scott and 
Crossman 1973). Genetically similar reproduc- 
ing populations inhabit three major river basins: 
Sacramento-San Joaquin, Columbia, and Fraser. 
The greatest number of white sturgeon are in 
the Columbia River Basin. 

Historically, white sturgeon inhabited the 
Columbia River from the mouth upstream into 
Canada, the Snake River upstream to Shoshone 
Falls, and the Kootenai River upstream to 
Kootenai Falls (Scott and Crossman 1973; 
Figure). White sturgeon also used the extreme 
lower reaches of other tributaries, but not exten- 
sively. Current populations in the Columbia 
River Basin can be divided into three groups: 
fish below the lowest dam, with access to the 
ocean (the lower Columbia River); fish isolated 
(functionally but not genetically) between 
dams; and fish in several large tributaries. 

The Columbia River has supported impor- 
tant commercial, treaty, and recreational white 
sturgeon fisheries. A commercial fishery that 
began in the 1880's peaked in 1892 when 2.5 
million kg ^5.5 million lb) were harvested 
(Craig and Hacker 1940). By 1899 the popula- 
tion had been severely depleted, and annual har- 
vest was very low until the early 1940's, but the 



population recovered enough by the late 1940's 
that the commercial fishery expanded. A 1.8-m 
(6-ft) maximum size restriction was enacted to 
prevent another population collapse. Total har- 
vest doubled in the 1970's and again in the 
1980's because of increased treaty and recre- 
ational fisheries. From 1983 to 1994, 15 sub- 
stantial regulatory changes were implemented 
on the mainstem Columbia River downstream 
from McNary Dam as a result of increased fish- 
ing. Columbia River white sturgeon are still 
economically important. Recreational, commer- 
cial, and treaty fisheries in the Columbia River 
downstream from McNary Dam were valued at 
$10.1 million in 1992 (Tracy 1993). 

Several factors make white sturgeon rela- 
tively vulnerable to overexploitation and 
changes in their environment. The fish may live 
more than 100 years (Rieman and Beamesderfer 
1990), and overexpolitation is well documented 
for long-lived, slow-growing fish (Ricker 
1963). Female white sturgeon are slow to reach 
sexual maturity; in the Snake River they mature 
at age 15-32 (Cochnauer 1981). Mature females 
in the Columbia Basin only spawn every 2-1 1 
years (Stockley 1981; Cochnauer 1983; Welch 
and Beamesderfer 1993). Sustainable harvest 
levels vary for impoundments in the Columbia 
River. Several impoundments are managed as 
groups, making overexploitation more likely in 



Our Living Resources — Fishes 



155 



impoundments with low sustainable harvest 
levels. 

White sturgeon populations in free-flowing 
and inundated reaches of the Columbia River 
Basin have been negatively affected by the abun- 
dant hydropower dams in most of the mainstem 
Columbia and Snake rivers (Rieman and 
Beamesderfer 1990). These dams have altered 
the magnitude and timing of discharge, water 
depths, velocities, temperatures, turbidities, and 
substrates, and have restricted sturgeon move- 
ment within the basin. Sturgeons in other river 
basins have declined in response to dam-induced 
habitat alterations (Artyukhin et al. 1978). 

Mainstem Columbia River 

Abundance and growth of white sturgeon are 
greatest in the lower Columbia River (Figure). 
These fish use estuarine and marine habitats as 
well as riverine habitats, allowing them to feed 
on anadromous prey fishes (those fishes travel- 
ing upriver from the sea to spawn; Tracy 1993). 
Although the lower Columbia River population 
may be the only one in this basin that is abun- 
dant and stable, even it is at some risk of col- 
lapse (Rieman and Beamesderfer 1990). Of the 
1 1 populations isolated between dams 
upstream, white sturgeon are known to be rela- 
tively abundant in only 3 (Figure). White stur- 
geon densities in three of the remaining eight 
populations are much lower than in the abun- 
dant populations. Data are sparse for the 
remaining five populations, although Zinicola 
and Hoines (1988) reported that in 1988 fewer 
than 10 white sturgeon were harvested in each 
of four of these impoundments and only 34 in 
another. 

Although the lower Columbia River popula- 
tion probably declined during the 1980's, adop- 
tion of more restrictive harvest regulations 
appears to have stabilized the population (Tracy 
1993). Successful spawning occurs each year in 
this reach (McCabe and Tracy 1993). Catch- 
per-unit-effort of most size groups in the three 
populations for which data are available 
declined considerably from 1987 to 1991; fish- 
eries there have collapsed and the populations 
are at risk of collapse (Beamesderfer and Rien 
1993). Recruitment in some populations 
appears limited to years with high river dis- 
charges in spring (Miller and Beckman 1993). 
Although most of the mainstem populations 
appear unstable, their genetic similarity to the 
stable lower Columbia River population has 
excluded them from consideration for listing 
under the federal Endangered Species Act. 

Overexploitation and poaching have reduced 
population size (Beamesderfer and Rien 1993), 
and impoundments and altered hydrographs 
caused by development of the hydropower sys- 





7 



i.^ Libby Dam 
[Kootenai Falls 



Lower 
Monumental 
Dam _ 

O tittle' 
% Ice Goose 
J Harbor Dam 
McNary Dam 
Dam 



Abundant 

Abundant but below 
historical levels 

Sparse 

Endangered (ESA) 

Extirpated 

Unknown 



Montana 



Oregon 



^^h 



Shoshone Falls 




tern have altered critical spawning habitat 
(Parsley et al. 1993). Because the factors identi- 
fied as causing declines in other white sturgeon 
populations are present to varying degrees in 
each of the other eight upstream impoundments, 
these populations are likely declining as well. 

Kootenai River 

Current research on white sturgeon in the 
Kootenai River indicates that this population is 
unstable and declining. The U.S. Fish and 
Wildlife Service listed the Kootenai River pop- 
ulation as endangered in 1994. 

This population has declined to fewer than 
1 ,000 fish, about 80% of which are more than 20 
years old. Apperson and Anders (1990) conclud- 
ed that virtually no recruitment has occurred 
since 1974, soon after Libby Dam began regu- 
lating flows, thereby altering historical dis- 
charge patterns of the river. This altering of dis- 
charge patterns is thought to be a major causal 
factor limiting recruitment into this unique stur- 
geon population. Research on the Kootenai 
River is examining the effects of increased dis- 
charge on the spawning behavior of white stur- 
geon. During 1993 increased discharges resulted 
in the collection of only three white sturgeon 
eggs despite intensive efforts to collect early 
lifestages of white sturgeon (Marcuson 1994). 

Fishing for white sturgeon in the Kootenai 
River has been regulated in Idaho since 1944, in 
Montana since 1957, and in British Columbia 
since 1952, indicating that overharvesting may 
have been affecting population size. Fishing for 
white sturgeon has been closed in Montana 
since 1979, and catch and release angling 



Figure. Distribution and status of 
white sturgeon in the U.S. portion 
of the Columbia River Basin. 



156 



Fishes — Our Living Resources 



- . ■■ a. -.y ..AVfc-», J^.' 




Fifteen-hundred-pound white stur- 
geon caught near Payette. Idaho, 
circa 1911. 



restrictions have been in place since 1984 in 
Idaho and 1990 in British Columbia. 

Snake River 

The Snake River has 12 dams from its mouth 
upstream to Shoshone Falls in Idaho. White 
sturgeon are believed to exist in small numbers 
in the lower three pools on the Snake River 
formed by Ice Harbor, Lower Monumental, and 
Little Goose dams (Zinicola and Hoines 1988). 
Of the nine impoundments upstream from Little 
Goose Dam, white sturgeon are relatively abun- 
dant in two, present at low numbers in six, and 
are absent in another (PSMFC 1992). 

Although little is known about the early life 
history and spawning habitat requirements of 
white sturgeon in the Snake River, the construc- 
tion and operation of the river's dams are likely 
to have the same effects as the impoundments 
on the Columbia and Kootenai rivers. White 
sturgeon appear more abundant in regions of the 
Snake River where free-flowing river habitat 
exists (PSMFC 1992), such as between Lower 
Granite and Hells Canyon dams where 76% of 
the river is free-flowing. Conversely, white stur- 
geon are not present in the impoundments cre- 
ated by Hells Canyon Dam and not abundant in 
the impoundment created by Oxbow Dam, 
which constitute two continuous slackwater 
regions (Welsh and Reid 1971). 

While free-flowing sections of the Snake 
River exist in varying proportions between the 
dams, impoundments upstream of these sec- 
tions influence both water temperature and the 
annual discharge pattern. At least 28 sturgeon 
died during July 1990 because of low dissolved- 
oxygen levels in Brownlee Pool (PSMFC 
1992). Sturgeon production in the Snake River 
also appears limited by dewatering from irriga- 
tion diversions (Lukens 1981) and small spawn- 
ing populations (Cochnauer et al. 1985). 



Harvest of white sturgeon from the Snake 
River has had a definite negative impact on 
these populations, but the magnitude of the 
effect is unknown. Commercial fishing was per- 
mitted on the Snake River until 1943; then 
increasingly restrictive regulations were imple- 
mented from 1944 to 1969. In 1970 catch and 
release regulations were imposed on the entire 
river. A recommendation has been made that 3 
of the 12 reaches of the Snake River discussed 
in this article be completely closed to fishing 
(Cochnauer et al. 1985). 

Summary 

Habitat changes (e.g., decreased discharges 
resulting in decreased spawning habitat) caused 
by development of the hydropower system have 
contributed to white sturgeon population 
declines in the Columbia River Basin; spawning 
habitat has been particularly affected by dams. 

Overharvest of white sturgeon has caused 
population declines in several Columbia River 
Basin populations, both historically and in the 
past two decades. Recent management changes 
have helped alleviate overharvest in much of the 
Columbia River Basin, but refinement of man- 
agement strategies is still needed in some areas. 

The status of the 25 Columbia River Basin 
white sturgeon populations varies considerably: 
1 is stable and abundant; 5 are relatively abun- 
dant, but probably at lower levels than in the 
past; 12 are sparse and many are declining; 5 
have unknown status but creel data suggest they 
are sparse; 1 is sparse, declining, and listed 
under the Endangered Species Act; and white 
sturgeon have probably been extirpated from 
another. Conditions that have contributed to 
stock declines in other white sturgeon popula- 
tions are present in populations whose status is 
unknown, suggesting that populations with 
unknown status may also be declining. 

References 

Apperson, K.A.. and P.J. Anders. 1990. Kootenai River 
white sturgeon investigations and experimental culture, 
annual progress report 1989. Bonneville Power 
Administration. Division of Fish and Wildlife Project 88- 
65. 50 pp. 

Artyukhin. Y.K., A.D. Sukhoparova. and L.G. Fimukhira. 
1978. The gonads of sturgeon. Acipenser giildenstcidii. in 
the littoral zone below the dam of the Volograd water 
engineering system. Journal of Ichthyology 18:912-923. 

Beamesderfer. R.C., and T.A. Rien. 1993. Dynamics and 
potential production of white sturgeon populations in 
three lower Columbia River reservoirs. Pages 175-206 in 
R.C. Beamesderfer and A. A. Nigro. eds. Status and habi- 
tat requirements of the white sturgeon populations in the 
Columbia River downstream from McNary Dam. Vol 1 . 
Final Report to Bonneville Power Administration. 
Portland. OR. 



Our Living Resources — Fishes 



157 



Cochnauer, T.G. 1981. Survey status of white sturgeon 
populations in the Snake River, Bliss Dam to C.J. Strike 
Dam. Idaho Department of Fish and Game, River and 
Stream Investigations, Job Performance Rep., Project F- 
73-R-2, Job I-b, Boise. 25 pp. 

Cochnauer, T.G. 1983. Abundance, distribution, growth, 
and management of white sturgeon Acipenser transmon- 
tanus in the middle Snake River. Idaho. Ph.D. disserta- 
tion. University of Idaho, Moscow. 52 pp. 

Cochnauer, T.G., J.R. Lukens, and F.E. Partridge. 1985. 
Status of white sturgeon, Acipenser transmontanus, in 
Idaho. Pages 127-133 in F.P. Binkowski and S.I. 
Doroshov, eds. North American sturgeons: biology and 
aquaculture potential. Dr. W. Junk, Dordrecht, The 
Netherlands. 

Craig, J. A., and R.L. Hacker. 1940. The history and devel- 
opment of the fisheries of the Columbia River. U.S. 
Bureau of Fisheries Bull. 49(32): 132-2 16. 

Lukens, J.R. 1981. Snake River sturgeon investigations: 
Bliss Dam upstream to Shoshone Falls. Idaho 
Department of Fish and Game, Boise. 24 pp. 

Marcuson, P. 1994. Kootenai River white sturgeon investi- 
gations, annual progress report 1993. Bonneville Power 
Administration. Division of Fish and Wildlife Project. 
88-65. 67 pp. 

McCabe, G.T., Jr., and C.A. Tracy. 1993. Spawning charac- 
teristics and early life history of white sturgeon 
Acipenser transmontanus in the Lower Columbia River. 
Pages 19-49 in R.C. Beamesderfer and A. A. Nigro, eds. 
Status and habitat requirements of the white sturgeon 
populations in the Columbia River downstream from 
McNary Dam. Vol. 1 . Final Report to Bonneville Power 
Administration, Portland, OR. 

Miller, A. I., and L.G. Beckman. 1993. A recruitment index 
for white sturgeon in the Columbia River downstream 
from McNary Dam. Pages 141-166 in R.C. 
Beamesderfer and A. A. Nigro, eds. Status and habitat 
requirements of the white sturgeon populations in the 
Columbia River downstream from McNary Dam. Vol. 2. 
Final Report to Bonneville Power Administration, 
Portland, OR. 



PSMFC. 1992. White sturgeon management framework 
plan. Pacific States Marine Fisheries Commission, 
Portland, OR. 201 pp. 

Parsley, M.J., L.G. Beckman, and G.T McCabe, Jr. 1993. 
Spawning and rearing habitat use by white sturgeons in 
the Columbia River downstream from McNary Dam. 
Transactions of the American Fisheries Society 
122(2):2 17-227. 

Ricker, W.E. 1963. Big effects from small causes: two 
examples from fish population dynamics. Journal of the 
Fisheries Research Board of Canada 20:257-264. 

Rieman, B.E., and R.C. Beamesderfer. 1990. White stur- 
geon in the lower Columbia River: is the stock overex- 
ploited? North American Journal of Fisheries 
Management 10:388-396. 

Scott, W.B., and E.J. Crossman. 1973. Freshwater fishes of 
Canada. Fisheries Research Board of Canada Bull. 184, 
Ottawa. 966 pp. 

Stockley. C. 1981. Columbia River sturgeon. Washington 
Department of Fisheries Prog. Rep. 150, Olympia. 28 pp. 

Tracy, C.A. 1993. Status of white sturgeon resources in the 
mainstem Columbia River. Final Report. 
Dingell/Johnson-Wallop/Breaux Project F-77-R, 
Washington Department of Fisheries, Battleground. 16 
pp. 

Welch, D.W.. and R.C. Beamesderfer. 1993. Maturation of 
female white sturgeon in lower Columbia River 
impoundments. Pages 89-108 in R.C. Beamesderfer and 
A. A. Nigro, eds. Status and habitat requirements of the 
white sturgeon populations in the Columbia River down- 
stream from McNary Dam. Vol. 2. Final Report to 
Bonneville Power Administration, Portland, OR. 

Welsh, T.L., and W.W. Reid. 1971. Hells Canyon fisheries 
investigations: 1970 annual report. Idaho Department of 
Fish and Game, Boise. 56 pp. 

Zinicola, T, Jr., and L.J. Hoines. 1988. Washington state 
sport catch report. Washington Department of Fisheries, 
Olympia. 83 pp. 



For further information: 

Allen I. Miller 

National Biological Service 

Northwest Biological Science 

Center 

Columbia River Research 

Laboratory 

M.P. 5.48L Cook-Underwood Rd. 

Cook, WA 98605 




Invertebrates 



Overview 



Invertebrates are impres- 
sive in abundance and 
diversity, living on land and in water and air. 
Many species are borne to distant places on air 
and water currents, and via modern transporta- 
tion. 

Of the millions of species of animals world- 
wide, about 90% are invertebrates, that is, ani- 
mals without backbones (Opler, Powell, this 
section). The arthropods, or jointed-leg inverte- 
brates such as beetles, account for 75% of this 
total. More than 90,000 described insect species 
inhabit North America (Hodges, Powell, this 
section); the Lepidoptera (butterflies and 
moths) alone account for about 1 1 ,500 of these 
(Powell, this section). 

Within an acre of land and water, hundreds 
of different invertebrates form an ecological 
web of builders, gatherers, collectors, predators, 
and grazers, all interacting with each other and 
each a necessary component of a healthy 
ecosystem. The large macroscopic inverte- 
brates — like bees, beetles, butterflies, grasshop- 
pers, snails, and earthworms — are well known, 
but other invertebrates are almost invisible 
because they are extremely tiny or camouflaged 
for protection. We have just begun to under- 
stand the ecology of some commercially impor- 
tant species, but we understand very little about 
the behavior, communication, and function of 



many other invertebrates within various ecosys- 
tems. 

Each individual invertebrate is a highly com- 
plex, specialized animal. Some molt (change or 
metamorphose) into several distinct life stages. 
For example, some insects transform from egg 
to larva, then to pupa, and finally emerge as a 
terrestrial winged adult. Some aquatic inverte- 
brates do not have pupal stages, and the larvae 
(nymphs or naiads) grow progressively larger 
by molts. Earthworms bear cocoons that each 
contain about six miniature juveniles; they also 
reproduce by fragmentation (architomy). 

Changes to the environment can disrupt 
basic interactions of invertebrate species, there- 
by affecting other organisms in the food chain. 
Disruptions of natural food cycles may cause 
drastic changes in the community structure and 
ecological web of life. This is especially true of 
the fauna that dwell in fragile ecosystems like 
caves and springs (Webb, see box). Eventually 
even humans are affected by changes to food 
webs and destruction of beneficial habitat for 
wildlife. 

Most invertebrates can survive extreme nat- 
ural events like severe storms, blizzards, and 
flooding. When confronted by unnatural distur- 
bances, however, such as excessive siltation 
from urban and highway developments, 
eutrophication (excessive nutrients) by runoff 



by 

Science Editor 

William T. Mason, Jr. 

National Biological 

Service 

Southeastern Biological 

Science Center 

7920 NW 71st St. 

Gainesville, FL 32653 



160 



Invertebrates — Our Living Resources 




Leaf miner moth (Acrocercops 
arbutella). 




Citophilus mealybug 
(Pseudot occus calceolariae). 



from agricultural lands, and contamination of 
aquatic habitats by toxic substances and acids, 
invertebrate populations can be severely dam- 
aged. Airborne toxicants like acid rain are 
harmful to the long-term well-being of insects. 
If disturbances are sufficient, natural fauna may 
be extirpated (removed or lost) and replaced by 
more tolerant kinds. This "unbalanced" situa- 
tion usually results in a population explosion of 
a few species (e.g., Tubificidae: Oligochaeta 
and red-blooded Chironomidae: Diptera). Such 
a biological reaction makes these aquatic inver- 
tebrates excellent bioindicators of overall envi- 
ronmental conditions (Bartsch and Ingram 
1959). The use of aquatic invertebrates for 
bioassay (testing the toxicity of substances to 
"standard" test organisms) has greatly helped to 
minimize adverse effects of contaminants on 
aquatic life. 

Butterflies and moths are particularly sus- 
ceptible to environmental disturbances (Opler, 
this section), although their responses to mild 
disturbances and changes may be slow, lasting 
decades (Otte, Swengel, and Swengel and 
Swengel, this section). McCabe (this section) 
concludes that some of the flux in biodiversity 
is likely due to the "edge effect" at the interface 
from one habitat to another, and not necessarily 
to anthropogenic (human-caused) disturbances. 

In the aquatic realm, organic chemicals and 
other toxic substances, acids and alkalis, and 
mine drainage can quickly decimate popula- 
tions of mussels, mayflies, and stoneflies, 
whereas reduced water flow and introduction of 
pollutants like silt and excessive nutrients 
(Mason et al., Webb, this section) cause a slow, 
relentless destruction of the indigenous fauna. 

In the past 50 years, nearly 72% of the 
United States' 297 native mussel species have 
become endangered, threatened, or of special 
concern (Williams and Neves, this section). 
Their populations have been damaged because 
of siltation, point and nonpoint source pollu- 
tion, and outright habitat destruction. 

The zebra mussel (Dreissena polymorpha) 
and some other nonindigenous species repre- 
sent "biological pollution" (Schloesser and 
Nalepa, this section), and should be considered 
much like toxic pollution for control and treat- 
ment. Non-native zebra mussels lack predators 
and have invaded nearly the full length of the 
Mississippi River and its major tributaries, 
threatening the native mussel fauna of the east- 
ern United States (Williams and Neves, this sec- 
tion). The impact of the zebra mussel and other 
nonindigenous species is covered in greater 
detail in the "Non-native Species" section of 
this report. 

Historical data bases (e.g., Otte, this section) 
have traditionally focused on commercially 
important invertebrate species such as clams 



and oysters. In contrast, little information exists 
on the status and trends of nonconsumptive. 
indigenous invertebrate life, and existing data 
are often not in formats for use in modern deci- 
sion-making tools (Messer et al. 1991 ). 

An important, often-overlooked problem 
with providing scientifically credible data 
involves the taxonomy and systematics (identi- 
fication and classification) of organisms. Today, 
our museum collections of invertebrates are 
often old and worn out, and there are few 
trained taxonomists to renew archival materials. 
In fact, many "type" specimens used for origi- 
nal species' descriptions in the early 1900's are 
unusable, making comparisons of recently col- 
lected specimens impossible. 

Canada has been doing continuous biomoni- 
toring for several decades, which has now 
resulted in status and trends analyses of subtle 
perturbations like acidification (Chmielewski 
and Hall 1993). It is clear that the success of 
future assessments in the United States will 
greatly depend on availability of and access to 
high-quality data; stop-gap measures are unlike- 
ly to prove successful because of inconsisten- 
cies caused by differing collection methods, 
taxonomy, and reporting units. 

This section is organized by general articles 
on invertebrates and followed by terrestrial and 
aquatic case studies. The authors drew on orig- 
inal data, often unpublished, and therefore, 
although some of the studies may appear out- 
dated, this does not detract from the usefulness 
of the examples. 

Basic research on the taxonomy and ecology 
of species and communities is urgently needed 
as groundwork for future status and trend 
assessments. Complex ecological relationships 
are poorly understood. Only a few working 
ecosystem models (e.g., Chesapeake Bay) are 
sufficiently developed to allow semi-quantita- 
tive predictions about cause-effect relationships 
between some biologic components (e.g., 
plankton) and abiotic conditions. Other biolog- 
ical components need to be added to the model- 
ing framework, especially as related to food 
web interactions. Future status and trends 
information gathering should be supportive of 
ecosystem model development wherever possi- 
ble. 

References 

Bartsch. A.F.. and W.M. Ingram. 1959. Stream life and the 
pollution environment. Public Works 90: 104-1 10. 

Chmielewski. CM., and R.J. Hall. 1993. Changes in the 
emergence of blackflies (Diptera: Simuliidae) over 50 
years from Algonquin Park streams: is acidification the 
cause? Canadian Journal of Fisheries and Aquatic 
Sciences 50:1517-1529. 

Messer. J.J.. R.A. Linthurst. and W.S. Overton. 1991. An 
EPA program for monitoring ecological status and 
trends. Environmental Monitoring and Assessment 
17:67-78. 



Our Living Resources — Invertebrates 



161 



Insects are the most diverse group of organ- 
isms (Wheeler 1990); potentially they are 
highly indicative of environmental change 
through close adaptation to their environment; 
they represent the majority of links in the com- 
munity foodchain; and they likely have the 
largest biomass of the terrestrial animals 
(Holden 1989). Thus, knowledge about them is 
fundamental to studying the environment. 

The 34 orders of insects have 90,968 
described species and an estimated 72,500+ 
undescribed species in 653 families and 12,578 
genera (Arnett 1985; Kosztarab and Schaefer 
1990) in America north of Mexico. Of the 
described species 71,931 are in the orders 
Coleoptera (beetles, 23,640), Diptera (flies, 
19,562), Hymenoptera (ants, bees, wasps, and 
sawflies, 17,429), and Lepidoptera (moths and 
butterflies, 11,300). Undescribed species are 
distributed mainly among Homoptera (aphids, 
leafhoppers, scale insects, and allies, 4,334), 
Coleoptera (2,627), Diptera (41,622), 
Hymenoptera ( 1 8,57 1 ), and Lepidoptera (2,700; 
Kosztarab and Schaefer 1990). 

Some aspects of the immature stages of 
8,668 species are known (Kosztarab and 
Schaefer 1990); however, very few are fully 
known (i.e., documented with voucher speci- 
mens and publications with illustrations of 
eggs, each larval instar, and pupae). Detailed 
knowledge of the immature stages is important 
because insects often are present as adults for a 
short period during the year, but are present as 
eggs, larvae, or pupae during most of the year. 
Taxonomic literature useful for identifying 
described species is available for less than 30% 
of them in the adult stage. No major order has 
been subjected to revisionary study at the spe- 
cific level, and only two such projects are under 
way, Lepidoptera (Dominick 1971+) and 
Diptera (Griffiths 1980+). Some smaller orders, 
some families, and many genera have been 
revised for North America (e.g., bethylid wasps 
[Evans 1978], cerambycid beetles [Linsley and 
Chemsak 1961-84], chrysidid wasps [Bohart 
and Kimsey 1982], dragonflies [Odonata; 
Needham and Westfall 1955], grasshoppers 
[Orthoptera; Otte 1981, 1983], lady beetles 
[Gordon 1985], springtails [Collembola; 
Christiansen and Bellinger 1980-81], thrips of 
Illinois [Thysanoptera; Stannard 1968], and 
beetles of the Pacific Northwest [Hatch 1953- 
71]). Several family or ordinal groups have been 
revised for Canada and the northern United 
States. Diptera (Stone et al. 1965; Systematic 
Entomology Laboratory, U.S. Department of 
Agriculture, unpublished), Heteroptera (Henry 
and Froeschner 1988), and Hymenoptera 
(Krombein et al. 1979) have been cataloged. 
The Lepidoptera have a checklist (Hodges et al. 



1983). A nomenclatorial data base (BIOTA, 
Biosystematic Information on Terrestrial 
Arthropods, available via Internet or on CD- 
ROM) for terrestrial arthropods (less Crustacea) 
is being developed and coordinated by the 
Systematic Entomology Laboratory, USDA 
(Hodges 1994). 

For all major orders much revisionary work 
is needed to define and discriminate among 
species, genera, and higher taxa in a broad sense 
and with recognition of variation in nearly all 
characters. From these works field guides and 
identification manuals must be developed. 
Literature for lay workers and students should 
provide identification to the species level by 
state or region as this information is necessary 
for conducting surveys (Keys to British 
Insects — a continuing publication series of the 
Royal Entomological Society, London — is an 
excellent example). 

Several states have programs to document 
their fauna with publications and voucher mate- 
rial: California Insect Survey, Florida State 
Collection of Arthropods, Illinois Natural 
History Survey, New York State Natural History 
Survey, and Insects of Virginia, Blacksburg. 
Few state faunal lists exist; the few that do are 
outdated or limited: all insects of New York 
(Leonard 1926) and North Carolina (Brimley 
1938, 1942; Wray 1950, 1967); Lepidoptera of 
Florida (Kimble 1965), Maine (Brower 1974, 
1983, 1984), New York (Forbes 1923, 1948, 
1954, 1960), and Pennsylvania (Tietz 1952). 
Checklists or faunal lists of Odonata exist for 39 
states and provinces (Westfall 1984). Surveys 
by county are under way for Kentucky 
(Lepidoptera, University of Louisville, unpub- 
lished data), Maryland (scattered orders and 
families, Maryland Entomological Society), 
Missouri (moths, J.R. Heitzman, unpublished 
data), Ohio (Lepidoptera, Ohio Lepidopterists; 
Metzler 1980; Iftner et al. 1992; Rings et al. 
1992; unpublished data), and the western 
United States (butterflies; Stanford and Opler 
1993). Extensive data have been collected on 
the distribution of Alaskan butterflies by the 
Alaska Lepidoptera Survey (Philip, University 
of Alaska, unpublished data). 

No site in North America has been fully sur- 
veyed for all insects; however, the Mount Desert 
Island, Maine, survey (Procter 1946) was an 
early attempt to do so. Of an estimated 6,000 
species, 3,400 have been reported from the H.J. 
Andrews Experimental Forest, Oregon (Parsons 
et al. 1991). Craters of the Moon National 
Monument, Idaho (Horning and Barr 1970); 
Deep Creek in San Bernardino County, 
California (S.I. Frommer, University of 
California, Riverside, unpublished data); and 
Pawnee Grasslands, Colorado (Kumar et al. 



Diversity and 
Abundance of 
Insects 



by 

Ronald W. Hodges 

U.S. Department of 

Agriculture Systematic 

Entomology Laboratory 




Leaf-footed bug (Thasus sp.). 




Mantidfly (Mantispa interrupta). 



162 



Invertebrates — Our Living Resources 




Robber fly (Diogmites sym- 
machus). 




Spurge hawkmoth (Hyles euphor- 

biae). 



1976) have been intensively surveyed for 
insects but none of the surveys approaches 
completion. A constant problem has been the 
inability to identify all the numerous taxa. 

Sampling for taxa, except for aquatics, is 
based mainly on adults; results are highly vari- 
able, depending on the competency of the sam- 
plers, knowledge of habits of organisms, weath- 
er during sampling periods, and phases of the 
moon and wavelength of light (for those species 
attracted to light). With exceptions (aquatic 
insects; Merritt et al. 1984), sampling tech- 
niques to estimate species diversity within an 
area have not been developed or are preliminary 
for limited taxa. 

Identification of adults within large orders 
depends on highly trained, experienced taxono- 
mists who have access to good collections and 
libraries; very few taxonomists exist relative to 
the number of taxa. Identifications in collec- 
tions must be held suspect unless the taxa have 
been revised in contemporary terms and the 
specimens studied and vouchered by the revisor 
(Hodges 1976) or other specialist. 

Individuals capable and willing to provide 
authoritative identifications are becoming fewer 
each year. Many have retired or could retire. 
There has been a significant redirection of sys- 
tematists from basic revisionary work to other 
research areas. Nearly 30% fewer persons are 
entering the field because the likelihood of 
obtaining a position upon completion of train- 
ing is extremely poor (Lutz 1994). Technical 
and monetary support for systematists and cura- 
tors always has been limited and is becoming 
more restricted. 

Collections vary in size from small private 
collections to the 30+ million specimens in the 
National Insect Collection in the National 
Museum of Natural History. Many state univer- 
sities, particularly in the Midwest and on the 
West Coast, have collections of 1+ million spec- 
imens, as do several private and public institu- 
tions. Despite this large number, many species 
are represented by few specimens and almost 
none with comprehensive representation by 
county and by state. 

Surveys of many taxa are possible but 
require individuals to initiate them; sufficient 
taxonomic literature and research to enable 
recognition of taxa; curatorial support for 
preparing, sorting, and identifying specimens 
and potential supervision of the surveys; and 
adequate collection and library facilities for 
species recognition and permanent storage of 
voucher specimens. 

These comments are meant to provide per- 
spective on the status of systematic entomology 
and thus the role insects may have in the work 
of the National Biological Service. 



References 

Arnett, R.H. 1985. American insects: a handbook of the 
insects of America north of Mexico. Van Nostrand 
Reinhold Co., New York. 850 pp. 

Bohart, R.M., and S.S. Kimsey. 1982. A synopsis of the 
Chrysididae in America north of Mexico. Memoirs of the 
American Entomological Institute 33:1-266. 

Brimley, C.S. 1938. The insects of North Carolina. North 
Carolina Department of Agriculture, Raleigh. 560 pp. 

Brimley, C.S. 1942. Supplement to insects of North Carolina. 
North Carolina Department of Agriculture, Raleigh. 39 pp. 

Brower, A.E. 1974. A list of the Lepidoptera of Maine — Part 

1, the macrolepidoptera. Life Sciences and Agriculture 
Experiment Station Tech. Bull. 66:1-136. 

Brower, A.E. 1983. A list of the Lepidoptera of Maine — Part 

2. Maine Department of Conservation and the Department 
of Entomology Tech. Bull. 109:1-60. 

Brower. A.E. 1984. A list of the Lepidoptera of Maine — Part 

2 (concluded). Maine Department of Conservation and the 

Department of Entomology Tech. Bull. 1 14:1-70. 
Christiansen, K.A.. and P. Bellinger. 1980-81. The 

Collembola of North America north of the Rio Grande, a 

taxonomic analysis. Grinnell College. Grinnell. IA. 4 vols. 
Dominick, R.B.. ed. 1971+. The moths of America north of 

Mexico, including Greenland. The Wedge Entomological 

Research Foundation, Washington. DC. [19 parts] 
Evans, H.E. 1978. The Bethylidae of America north of 

Mexico. Memoirs of the American Entomological Institute 

27:1-332. 
Forbes, W.T.M. 1923. The Lepidoptera of New York and 

neighboring states. Part 1 . Cornell University Agricultural 

Experiment Station Memoir 68:1-729. 
Forbes, W.T.M. 1948. The Lepidoptera of New York and 

neighboring states. Part 2. Cornell University Agricultural 

Experiment Station Memoir 274:1-263. 
Forbes. W.T.M. 1954. The Lepidoptera of New York and 

neighboring states. Part 3. Cornell University Agricultural 

Experiment Station Memoir 329:1-433. 
Forbes, W.T.M. 1960. The Lepidoptera of New York and 

neighboring states. Part 4. Cornell University Agricultural 

Experiment Station Memoir 371:1-188. 
Gordon. R.D. 1985. The Coccinellidae (Coleoptera) of 

America north of Mexico. Journal of the New York 

Entomological Society 93(1): 1-912. 
Griffiths, C.D.G.. ed. 1980+. Flies of the Nearctic Region. E. 

Schweizerbart'sche Verlagsbuchhandlung. Stuttgart. [19 

parts] 
Hatch, M.H. 1953-71. The beetles of the Pacific Northwest. 

Part 1: Introduction and Adephaga, 340 pp.: Part 2: 

Staphyliniformia. 384 pp.; Part 3: Pselaphidae and 

Diversicornia I. 503 pp.: Part 4: Macrodactyles. 

Palpicornes. and Heteromera, 268 pp.; Part 5: 

Rhipiceroidea, Sternoxi, Phylophaga. Rhynchophora, and 

Lamellicornia, 662 pp. University of Washington Press. 

Seattle. 
Henry, T.J.. and R.C. Froeschner. 1988. Catalog of the 

Heteroptera, or true bugs, of Canada and the continental 

United States. E.J. Brill, Leiden. The Netherlands. 958 pp. 
Hodges. R.W. 1976. Presidential address 1976 — what insects 

can we identify? Journal of the Lepidopterists* Society 

30:245-251. 
Hodges. R.W. 1994. BIOTA. Association of Systematics 

Collection Newsletter 21(6):72. 
Hodges. R.W., et al., eds. 1983. Check list of the Lepidoptera 

of America north of Mexico. E.W. Classey Ltd. and the 

Wedge Entomological Research Foundation. London. 

England. 284 pp. 
Holden. C. 1989. Entomologists wane as insects wax. Science 

246:754-756. 
Horning. D.S., Jr., and W.F. Barr. 1970. Insects'of Craters of 

the Moon National Monument, Idaho. University of Idaho 

College of Agriculture Miscellaneous Series 8:1-118. 



Our Living Resources — Invertebrates 



163 



Iftner, D.C.. J.A. Shuey, and J.V. Calhoun. 1992. Butterflies 

and skippers of Ohio. Ohio Biological Survey Bull. 9(1):1- 

212. 
Kimble, C.P. 1965. Lepidoptera of Florida. Arthropods of 

Florida and Neighboring Land Areas 1:1-363. 
Kosztarab, M., and C.W. Schaefer. 1990. Conclusions. Pages 

241-247 in M. Kosztarab and C.W. Schaefer, eds. 

Systematics of the North American insects and arachnids: 

status and needs. Virginia Agricultural Experiment Station 

Information Series 90- 1 . 
Krombein, K.V., P.D. Hurd, Jr., D.R. Smith, and B.D. Burks. 

1979. Catalog of the Hymenoptera in America north of 

Mexico. Smithsonian Institution Press, Washington, DC. 

2,735 pp. 
Kumar, R., R.J. Lavigne, J.E. Lloyd, and R.E. Pfadt. 1976. 

Insects of the Central Plains Experimental Range Pawnee 

National Grassland. University of Wyoming Agricultural 

Experiment Station Science Monograph 32:1-74. 
Leonard, M.D., ed. 1926. A list of the insects of New York 

with a list of the spiders and certain other allied groups. 

Cornell University Agricultural Experiment Station 

Memoir 101:1-1,121. 
Linsley, E.G., and J.A. Chemsak. 1961-84. The 

Cerambycidae of North America. Parts 1-7. University of 

California Press, Berkeley. 
Lutz, D. 1994. More than stamp collecting. American 

Scientist 82(2): 120-121. 
Merritt, R.W., K.W. Cummins, and V.H. Resch. 1984. 

Collecting, sampling, and rearing methods for aquatic 

insects. Pages 11-26 in R.W. Merritt and K.W. Cummins, 

eds. An introduction to the aquatic insects of North 

America. Kendall/Hunt, Dubuque. IA. 
Metzler, E.H. 1980. Annotated checklist and distribution 

maps of the royal moths and giant silkworm moths 

(Lepidoptera: Saturniidae) in Ohio. Ohio Biological 

Survey Biological Notes 14:1-10. 
Needham, J.G., and M.J. Westfall, Jr. 1955. A manual of the 

dragonflies of North America (Anisoptera). University of . 

California Press, Berkeley. 615 pp. 



Otte, D. 1981. North American grasshoppers. Vol. 1. 

Gomphocerinae and Acridinae. Harvard University Press, 

Cambridge, MA. 275 pp. 
Otte, D. 1983. North American grasshoppers. Vol. 2. 

Oediodinae. Harvard University Press, Cambridge, MA. 

366 pp. 
Parsons, G.R., G. Cassis, A.R. Moldenke, J.D. Lattin, et al. 

1991. Invertebrates of the H.J. Andrews Experimental 
Forest, Western Cascade Range, Oregon. V: An annotated 
list of insects and other arthropods. U.S. Forest Service 
General Tech. Rep. 290:1-168. 

Procter, W. 1946. Biological survey of the Mount Desert 

Region. Part 7. Wistar Institute, Philadelphia, PA. 566 pp. 

Rings, R.W., E. H. Metzler, F. J. Arnold, and D.H. Harris. 

1992. The owlet moths of Ohio, order Lepidoptera family 
Noctuidae. Ohio Biological Survey Bull. 9(2): 1-222. 

Stanford, R.E., and PA. Opler. 1993. Atlas of western U.S.A. 

butterflies, including adjacent parts of Canada and Mexico. 

Published by authors, Denver, CO. 275 pp. 
Stannard, L.J. 1968. The thrips, or Thysanoptera, of Illinois. 

Illinois Biological Monographs 25:1-200. 
Stone, A., C.W. Sabrosky, W.W. Wirth, et al. 1965. A catalog 

of the Diptera of America north of Mexico. Agriculture 

Handbook 276:1-1696. 
Tietz, H.M. 1952. The Lepidoptera of Pennsylvania. 

Pennsylvania State College, School of Agriculture, 

Agriculture Experiment Station. State College, PA. 194 pp. 
Westfall, M.J., Jr. 1984. Odonata. Pages 126-176 in R.W. Merritt 

and K.W. Cummins, eds. An introduction to the aquatic 

insects of North America. Kendall/Hunt, Dubuque, IA. 
Wheeler, Q.D. 1990. Insect diversity and cladistic constraints. 

Annals of the Entomological Society of America 

83(6):1031-1047. 
Wray, D.L. 1950. Insects of North Carolina: second supple- 
ment. North Carolina Department of Agriculture, Raleigh. 

59 pp. 
Wray, D.L. 1967. Insects of North Carolina: third supplement. 

North Carolina Department of Agriculture, Raleigh. 181 pp. 




Tiger beetle (Cicindela hirticollis). 



For further information: 

Ronald W. Hodges 

Systematic Entomology Laboratory, 

USDA 

c/o National Museum of Natural 

History, MRC- 168 

Washington, DC 20560 



Grasshoppers (Orthoptera:Acrididae) are 
perhaps the most important grazing herbi- 
vores in the nation's grasslands, which from a 
human standpoint, are the most important 
food-producing areas. The damage that 
grasshoppers do to plants varies with the 
species. A few dozen species at most are highly 
injurious to crops, while those that feed on eco- 
nomically unimportant plants may have no 
measurable impact, and those that feed on detri- 
mental plants are highly beneficial. Given such 
differences, it becomes important to distinguish 
properly between harmful and beneficial 
species. Grasshopper abundance in all kinds of 
grasslands means they are an important factor in 
the ecological equation. Their economic impor- 
tance — positive and negative — means that they 
must be included in all studies of grassland and 
desert-grassland communities. 



Sciences in Philadelphia (ANSP) reveal that 
approximately 20% of the U.S. species repre- 
sented in the existing ANSP collection are 
undescribed (Otte 1981; unpublished data). 
Most new species belong to the very large genus 
Melanoplus, which contains some of the most 
injurious grasshopper species known. A consid- 
erable number of undescribed species are from 
the eastern states, from approximately central 
Texas to New England. New species are turning 
up even in extremely well-studied areas such as 
Michigan and Florida. It is expected that at least 
tens of species remain to be discovered in the 
coastal ranges of California, and many other 
mountain peaks in the western states should 
have species unique to them. Much of the acad- 
emy's collecting efforts have been directed to 
investigating the grasshopper faunas of such 
mountain peaks ("sky islands"). 



Grasshoppers 



by 

Daniel Otte 

Academy of Natural Sciences, 

Philadelphia 



Taxonomic Status 

More than 1,000 species of grasshoppers 
have been described from the United States 
(Otte 1976, 1994, unpublished data base). 
Taxonomic revisions at the Academy of Natural 



Natural Range Increases 

Great Lakes Region 

Documenting natural range changes requires 
that comparable collections be made at several 



164 



Invertebrates — Our Living Resources 



points in time. The only such case involving 
grasshoppers that I am aware of involves the 
ranges of two grasshopper species along the 
Great Lakes shores. Trimerotropis huroniana 
and T. maritima displace one another on the 
dunes surrounding the Great Lakes, with T. 
huroniana occupying the northern shores and T. 
maritima the southern shores (Otte 1970). The 
boundary between these two species has shifted 
in the last seven decades. The two species may 
well be competitive on four different lakefronts, 
on the north-south shores of Lakes Michigan 
and Huron. 

Prairie Peninsula 

In southern Michigan the bandwing 
grasshopper (Pardalophora haldemani) was 
abundant in 1943 and the related species, P. 
apiculata, was rare (Cantrall 1943). By 1968 P. 
haldemani had been completely replaced by P. 
apiculata, probably because subtle habitat 
changes gave P. apiculata an advantage over the 
strictly prairie species P. haldemani. 

Unnatural Range Increases 

Precise documentation of range changes in 
grasshoppers could be achieved if historical col- 
lecting sites could be resurveyed today. We are 
reasonably certain, though, that the cutting of 
eastern forests (mainly during the last century) 
opened up habitats for numerous species adapt- 
ed to grasslands and forest edges. Numerous 
prairie margin species now occur widely in the 
eastern United States in areas that were almost 
completely covered by forests. By colonizing 
roadsides, other species have become extremely 
widely distributed. The Carolina locust 
(Dissosteira Carolina), for example, is a ubiqui- 
tous roadside species that is now found in pre- 
viously heavily forested regions. Whether the 
overall range (outer limits of the range) has 
changed is debatable because the species inhab- 
its river margins and small natural eroded areas 
within the eastern forest region. 

In the western United States, certain species 
do well in eroded habitats that often result from 
overgrazing. Thus, the ranges of species spe- 
cializing on eroded ground probably increased 
along with increases in grazing. The clear- 
winged grasshopper (Camnula pellucida), a 
pest species from the northern Great Plains that 
greatly damages crops in the northern United 
States and western Canada, is now extremely 
abundant in overgrazed mountain meadows in 
the western states and is a good indicator of 
meadow degradation there. 

Many pest species specialize on agricultural 
fields; their ranges have increased because of 
irrigation and the planting of crops in normally 
desert habitats (e.g., migratory grasshopper 



[Melanoplus sanguinipes], two-striped 
grasshopper [M. bivittatus], and differential 
grasshopper [M. differentialis]). Ball et al. 
(1942) documented numerous cases of 
grasshoppers moving into areas altered by agri- 
cultural practices. 

Range Reductions and 
Extinctions: Case Studies 

The Rocky Mountain Locust 

Although it was the most abundant species 
during much of the last century in western 
North America, the Rocky Mountain locust (M. 
spretus) is now extinct; no specimens have been 
collected in this century. This species spread its 
destruction over many western states and was 
the source of great difficulty for early farmers 
east of the Rocky Mountains. The complete dis- 
appearance of the species has puzzled biologists 
for decades. The most reasonable hypothesis is 
that this species reproduced mainly along river 
valleys in Montana and Idaho and that with the 
heavy grazing of these habitats, beginning in the 
last part of the 1800's, these breeding areas 
were so heavily disturbed that breeding was dis- 
rupted (Lockwood and DeBrey 1990). Today, 
frozen remains of this species can still be found 
in glaciers in Montana. 

California Coastal Ranges 

The ANSP collections revealed that two 
undescribed species of Melanoplus were collect- 
ed only in what is now downtown San 
Francisco. Recent revisions of the Marginatus 
group of the genus Melanoplus (Otte 1981, 
1994, unpublished data base) reveal that the 
coastal ranges of California contain numerous 
members of this group, but that the ranges of 
many of the species are extremely limited. A 
subgroup of the Marginatus group speciated 
around the San Francisco Bay area, two species 
are known from the Berkeley area, two from San 
Francisco proper, and several from the north 
side of San Francisco Bay. The San Francisco 
species were collected in the first decade of this 
century when some natural vegetation still exist- 
ed in San Francisco. South of San Francisco 
these species are replaced by related species. 
Several other species in the group are known 
only from the Monterey Bay region, and one 
species only from a single locality. 

Two Rare Species 

Two individuals of an extremely rare 
grasshopper species (Eximacris superbum 
Hebard) were collected in south Texas. 
Repeated efforts to collect the species have not 
met with success, although the species possibly 



Our Living Resources — Invertebrates 



165 



breeds only during winter or in the early spring 
and might still turn up when an effort is made 
to collect it in early spring. The only relative in 
this genus (E. phenax Otte) is known from a sin- 
gle male collected at Big Cedar in the Kiamichi 
Mountains of Oklahoma. Searches for this 
species have also been unsuccessful; again, it is 
possible that the species overwinters in the adult 
stage and therefore is not present during normal 
grasshopper breeding times. 

Mountain Islands 

Some species of grasshopper are known 
only from mountain tops (sky islands). In the 
East, some Melanoplus species are known from 
single balds (grassy mountain summits) in the 
Appalachian region (three new species are 
presently being described; Otte, unpublished 
data). In the western United States members of 
the Montanus group are also known only from 
single localities (A.B. Gurney, unpublished 
data). Surveys of mountains in Colorado, New 
Mexico, Arizona, Utah, and Nevada showed 
that some of these species have not yet been 
described and are believed to occur only on sin- 
gle mountains. 

Within their limited ranges on mountains, 
the grasshopper species are further limited by 
environmental disturbance. I have encountered 
many overgrazed mountain meadows, some- 
times even highly isolated ones surrounded by 
forest. These differ from ungrazed meadows 
chiefly in the height of the vegetation and the 
number of plant species there, and consequent- 
ly in the incidence of short-winged grasshop- 
pers. Collections from high mountain passes, 
where meadows are partly protected from cattle 
by fences along the road, show a clear effect of 
vegetation length on diversity: in the protected 
areas, nonflying grasshopper species are pre- 
sent, sometimes in large numbers, but are 
absent in grazed areas, while flying species, 
which have wide distributions (weedy species), 
are common. The principal reason for the dif- 
ference appears to be that short-winged, nonfly- 
ing species are highly vulnerable to bird preda- 
tion, and without protective vegetation are 
unable to survive. 

Pleistocene Islands in Northern Florida 

The northern half of Florida contains a num- 
ber of habitats that remained exposed as islands 
during interglacial periods. Several grasshopper 
groups have species associated with these for- 
mer islands and species' ranges are highly 
restricted (Hubbell 1932). These areas are also 



ideal for farming and therefore have been great- 
ly altered during the last 50-80 years. It is 
extremely likely that some species never col- 
lected were lost. It remains to be seen which 
species collected earlier this century still exist. 

Management Implications 

Large differences exist in range sizes 
between species that can fly and those that can- 
not (Otte 1979). In the latter group are numer- 
ous species known from a single or a few local- 
ities. Most of these inhabit island habitats (iso- 
lated bogs, prairie openings within the eastern 
forests, balds on the Appalachian range, moun- 
tain meadows on western mountaintops, ham- 
mocks in Florida, and perhaps coastal islands 
along the East coast). Many species in these 
regions have probably already been lost. Others 
can be saved by creating new sanctuaries and 
properly modifying existing ones. Within such 
regions it should be possible to set aside small 
sanctuaries or strings of sanctuaries from which 
cattle and other grazing mammals are excluded. 
Such sanctuaries already exist along highways 
where cattle are kept away from roadsides and 
railways. 

References 

Ball, E.D., E.R. Tinkham. R. Flock, and C.T. Vorhies. 1942. 
The grasshoppers and other Orthoptera of Arizona. Tech. 
Bull. Arizona College of Agriculture 93:275-373. 

Cantrall, I.J. 1943. The ecology of the Orthoptera and 
Dermaptera of the George Reserve, Michigan. 
Miscellaneous Publ. of the University of Michigan 
Museum of Zoology 54:1-184. 

Hubbell, T.H. 1932. A revision of the puer group of the 
North American genus Melanoplus, with remarks on the 
taxonomic value of the concealed male genitalia in the 
Cyrtacanthacridinae (Acrididae). University of Michigan 
Museum of Zoology Miscellaneous Publ. 23:1-64. 

Lockwood, J. A., and L.D. DeBrey. 1990. A solution for the 
sudden and unexplained extinction of the Rocky 
Mountain locust, Melanoplus spretus (Walsh). 
Environmental Entomology 19:1194-1205. 

Otte. D. 1970. A comparative study of communicative 
behavior in grasshoppers. University of Michigan 
Museum of Zoology Miscellaneous Publ. 141:1-168. 

Otte, D. 1976. Species richness patterns of New World 
desert grasshoppers in relation to plant diversity. Journal 
of Biogeography 3:197-207. 

Otte. D. 1979. Biogeographic patterns in flight capacity of 
Nearctic grasshoppers (Orthoptera, Acrididae). 
Entomological News 90(4): 153- 158. 

Otte. D. 1981. The North American grasshoppers. Vol 1. 
Acrididae: Gomphocerinae and Acridinae. Harvard 
University Press, Cambridge, MA. 275 pp. 

Otte, D. 1994. The Orthoptera species file: computer cata- 
log to the genera and species of world grasshoppers. 
Academy of Natural Sciences of Philadelphia. 
Unpublished data base. 



For further information: 

Daniel Otte 

Academy of Natural Sciences 

Department of Entomology 

1900 Benjamin Franklin Parkway 

Philadelphia, PA 19103 



166 



Invertebrates — Our Living Resources 



The Changing 
Insect Fauna 
of Albany's 
Pine Barrens 



by 

Tim L. McCabe 

New York State Museum 



Table. Insect species historically 
recorded from the Albany pine 
barrens but now extirpated (modi- 
fied after McCabe et al. 1993). 



Sand plains and similar inland sand deposits 
are desertlike islands in a sea of moist land. 
Because of rapid drainage of rainwater, sand 
plains are modern-day refugia that represent 
drier conditions that have existed off and on 
during the past 10,000 years. Drainage makes 
for drier soils that mimic prairie conditions and 
consequently harbor prairie relicts; thus these 
communities support a specialized flora and 
fauna. Sand barrens abound with rare or endem- 
ic forms, many of which are endangered. 

The Albany pine barrens is a sand plains 
community and one of a relatively few scrub- 
oak {Quercus ilicifolia), pitch-pine (Pinus rigi- 
da) communities. Around the turn of the centu- 
ry, the Albany pine barrens was the site of inten- 
sive collecting by museum entomologists. 
Consequently, it has a historically well-docu- 
mented and diverse insect fauna, making it pos- 
sible to compare the fauna after a century of 
transition. Today, the region is heavily urban- 
ized, and only 15.5 km 2 (6 mi 2 ) of the original 
104 km 2 (40 mi 2 ) of natural barrens remain. As 
this habitat has been lost, 3 1 species of butter- 
flies, moths, and skippers (Lepidoptera) have 
become locally extinct during the last century 
(McCabe et al. 1993). The past two decades 
have witnessed the most rapid change to the 



Order 



Family 



Species 



Coleoptera 
Diptera 

Odonata 
Lepidoptera 



■■■■■MH 



Cicindelidae 
Asilidae 

Libellulidae 
Hespenidae 



Nymphalidae 
Noctuidae 







Geometridae 



Megalopygidae 
Saturniidae 

Sphingidae 



Cicindela patruela 
Cyrtopogon laphriformis 
Promachus bastardii 
Williamsonia lintneri 
Poanes viator 
Erynnis brizo 
E. persius 
Speyeria idalia 
Phyciodes batesii 
Acronicta lanceolaria 
A. radcliflei 
Agroperina lutosa 
Anomogyna badicollis 
Argyrostrotis quadrifiliaris 
Catocala pretiosa 
Eugraphe subrosea 
Homohadena badistriga 
Lithophane georgii 
L. lepida 
L. semiusta 
L thaxleri 
Platypolia anceps 
Psectraglaea carnosa 
Pyrelerra ceromatica 
Xylena cineritia 
X. thoracica 
Xylotype capax 
Metarrhanthis apiciaria 
Brephos inlans 
Semiothisa eremiata 
Megalopyge cnspata 
Citheronia sepulchralis 
C. imperials 
Hemaris gracilis 
Darapsa versicolor 



Albany pine barrens as well as the most dra- 
matic decline of its resident insects. 

Insect Surveys and Data 
Collection 

A general survey of all insect species includ- 
ed collections made using malaise traps, light 
traps, and netting. Because pine barren commu- 
nities require regular disturbance regimes (e.g., 
fire) to maintain the unique open habitats that 
characterize them, we evaluated insects in areas 
that had been recently burned. Postburn sites of 
1,5, 12, and 30 years of age were sampled. I 
gathered published records from numerous 
sources and, through comparison with recent 
catalogs and museum holdings, I attempted to 
identify those species that have a restricted dis- 
tribution or at least are unusual for New York 
State (McCabe et al. 1993). The population of 
the Karner blue butterfly (Lycaeides melisso 
samuelis) was the focus of an intensive moni- 
toring program using a visual transect method 
(Higgins et al. 1991; McCabe et al. 1993; 
Meyer and McCabe 1993). Better known and 
easily identified groups have also been evaluat- 
ed (McCabe and Huether 1985 [1986]; McCabe 
1985; McCabe et al. 1993: McCabe and C. 
Weber, unpublished data). 

Changes in Species Composition 

The group for which I am able to make the 
most reliable comparisons is the Lepidoptera. 
particularly the owlet moths (Noctuidae). 
Unfortunately, I began investigations too late 
(1980) to witness the extirpation of many of the 
species historically recorded from Albany's 
pine barrens (Table). Of the 31 species of 
Lepidoptera extirpated from the pine barrens, 5 
are partial to wetland habitats, which have suf- 
fered severely in the pine barrens: a skipper 
{Poanes viator), a sphinx {Darapsa versicolor), 
and three owlets (Agroperina lutosa, Eugraphe 
subrosea, and Argyrostrotis quadrifiliaris). Two 
owlet species (Xylena cineritia and Acronicta 
lanceolaria) are known to cycle in and out of an 
area in unpredictable patterns; thus their recent 
absence is thought temporary. Most of the 
remaining species now have distributions to the 
south (owlets: Catocala pretiosa, Pyreferra 
ceromatica, and Xylotype capax; flannel moth: 
Megalopyge crispata; giant silkworm moths: 
Citheronia sepulchralis and C. imperialis) or to 
the north (owlets: Xestia (Anomogyna) badicol- 
lis, Lithophane georgii, L. lepida, L. 'semiusta, 
L. thaxteri, Platypolia anceps, and Xylena tho- 
racica: geometer: Brephos infans: sphinx: 
Hemaris gracilis). Many of these species are 



Our Living Resources — Invertebrates 



167 



not restricted to pitch-pine barrens, but the 
Albany pine barrens represents important habi- 
tat at the extreme edges of their ranges. 

The species at the margins of their distribu- 
tion in Albany have witnessed losses almost 
equally divided between north and south, sug- 
gesting that regular "pulses" of an insect 
species' distribution account for more species 
losses than can be attributed to the nearly seven- 
fold loss of habitat. It therefore seems appropri- 
ate to look closer at those species whose decline 
is most relevant to habitat loss. 

The owlets Psectraglaea carnosa and 
Chaetaglaea cerata are usually found in coastal 
heath habitats but have been recorded from 
Albany. Chaetaglaea cerata is at precariously 
low levels in Albany, and P. carnosa is now local- 
ly extinct. Recent records of C. cerata and the 
last reports of P. carnosa were from an area of the 
pine barrens adjacent to the current landfill. 

Another once-common species in the pine 
barrens is the owlet Homohadena badistriga, 
but I have observed this moth only once during 
the last 4 years (1989-93). Homohadena badi- 
striga caterpillars show a marked preference for 
the native shrub Lonicera dioica over all other 
Lonicera in the area. This shrub species, which 
appears to be a favorite browse of deer (person- 
al observation), has become far less abundant in 
the past 12 years (J. Mattox, Bard College, per- 
sonal communication). None of 27 bushes of L. 
dioica I had visited in 1982 exist today. 

The owlet Agrotis stigmosa, which favors 
the periphery of open dunes, has a simpler story. 
The two most substantial open dunes in the 
Albany barrens have recently been developed, 
and A. stigmosa has subsequently been rarely 
encountered and may soon be lost. 

The Karner blue butterfly {Lycaeides melis- 
sa samuelis), now listed as an endangered 
species, has markedly declined in the Albany 
barrens (Figure). This species appears to be a 
barrens relict that has been losing ground over 
all of the Northeast. Its larvae feed on Lupinus 
perennis (lupine). Another lycaenid butterfly, 
Incisalia irus, also dependent on lupine, has 
suffered a similar decline. The continued 
decline of L. melissa samuelis on the Albany 
pine plains (Figure) is illustrated by using both 
recent data (Higgins et al. 1991; Meyer and 
McCabe 1993) and earlier population estimates 
of Cryan (1980) and Schweitzer (1988, 1990). 
This downward trend continues even though 
some sites now support more lupine than a 
decade ago and appear to be well protected. 

Pine Barrens Management 

Native pine barrens plants such as pitch 
pines, New Jersey tea, and lupine are very diffi- 
cult to establish successfully. Seedlings are 



shaded out by scrub oak. Young pitch pines are 
heavily browsed by deer and severely attacked 
by an introduced pine sawfly; younger plants 
are completely defoliated. Lupines are devoured 
by cottontail rabbits. Most characteristic pine 
barrens plants require open, disturbed sites. 

Fire has been scientifically employed as a 
management practice on the Albany barrens 
only quite recently. Scrub oak successfully 
regenerates after burns, as does the locust, 
Robinia pseudoacacia, a tree introduced from 
the Southeast for fence posts. One of the pine 
barrens rarities is Chytonix sensilis, a fungus- 
feeding moth. The year after a burn, fire-black- 
ened trunks support luxurious growths of this 
fungus. Despite this, C. sensilis was most abun- 
dant in 12-year-old burn sites where hardly any 
fungus had been present. In areas unburned for 
more than 30 years, only C. sensilis females 
were collected. One 12-year-old site is the same 
one that supports Chaetaglaea cerata and had 
supported P. carnosa, suggesting that a burn 
frequency of at least 1 2 years is best to promote 
some of the choicest pine barrens associates. I 
trapped moths extensively in postburn sites of 1, 
5, 12, and 30 years of age. No site was available 
with a postburn age between 12 and 30 years; 
an optimal burn frequency will likely fall some- 
where within this range. A frequent burn sched- 
ule would be highly detrimental to insect 
species very susceptible to fires, such as one of 
the elfin butterflies, Incisalia henrici. 

Species on the periphery of their range may 
not be reliable indicators of habitat quality. 
Natural fluctuation in range limits appears more 
significant than formerly considered. This can 
be attested to by the extirpation of 3 1 , and the 
addition of 32, moth species. The decline of 
characteristic pine barrens species has to be 
examined on a case-by-case basis. 

The Albany pine barrens has also been 
adversely affected by vehicular traffic, wind- 
breaks created by roads and buildings, develop- 
ment of open dunes, introductions of exotic 
species, and even the frequency of fires, which 
promote some and compromise other pine barren 
rarities. Cutting to create oak openings should be 
considered as a management practice. In addi- 
tion, open dunes may have to be artificially 
maintained where artificial windbreaks interfere. 

References 

Cryan, J.F. 1980. The Karner blue butterfly (Lycaeides 
melissa samuelis Nabokov) in the Hudson Valley sand 
belt of New York. Part 2. An annotated list of Hudson 
Valley sand belt populations and their status. A report for 
the New York State Department of Environmental 
Conservation. 

Higgins, L.E..T.L. McCabe, A. Meyer, and M. Rusch. 1991. 
Albany pine bush preserve — 1991 entomological report. 
Prepared for The Nature Conservancy and the City of 
Albany, NY. 




Figure. Decline of the Karner 
blue butterfly at Willow Avenue 
site in Albany (McCabe et 
al.1993). 



16H 



Invertebrates — Our Living Resources 



For further information: 

Tim L. McCabe 

New York State Museum 

The State Education Department 

University of the State of New York 

Albany, NY 12230 



McCabe, T.L. 1985. An annotated list of pine bush caddis 

(Insecta: Trichoptera). Skenectada 3:17-18. 
McCabe, T.L., and J.P. Huether. 1985(1986]. An annotated 

list of pine bush Cerambycidae (Insecta: Coleoptera). 

Skenectada 3:19-23. 
McCabe, T, A. Meyer, C. Weber, and L. Higgins. 1993. 

Albany pine bush project 1991-1992 entomological 

report. Submitted to the Eastern New York Chapter of 

The Nature Conservancy. Ill pp. 
Meyer, A.M., and T.L. McCabe. 1993. Albany pine bush 

project. Karner blue butterfly report. The Nature 

Conservancy. Unpublished report. 



Schweitzer, D.F. 1988. Supplement to 1988 Karner blue 
population studies: the Crossgates Mall population. A 
consultant's report to the City of Albany. NY. 
Unpublished report. 5 pp. 

Schweitzer, D.F. 1990. The 1990 status of selected Karner 
blue remnants in Saratoga and Albany counties. New 
York, with a discussion of monitoring methods. New 
York Department of Environmental Conservation, 
Endangered Species Unit. 



Lepidoptera 
Inventories in 
the 

Continental 
United States 



by 

Jerry A. Powell 

University of California, 

Berkeley 

Essig Museum of Entomology 



Lepidoptera (butterflies and moths) make up 
about 13% of the described and named 
90,000 insect species of North America ( 1 1,500 
named) and are among the better known large 
orders, although no complete inventory of 
Lepidoptera species exists for any state, county, 
or locality in North America. 

The rationale for local or regional inventory 
of insects is related to their importance in biodi- 
versity. Insects make up 75% of all described 
animals, and in natural communities their 
species outnumber those of all other higher 
organisms combined. Thus interrelationships 
between insects and other organisms form the 
■most prevalent and comprehensive elements of 
the fabric of biological communities. 

Lepidoptera are the major group of plant- 
feeding insects, and local inventories of 
Lepidoptera can help indicate the stability and 
diversity of plant communities. When we have 
several reasonably complete local inventories of 
Lepidoptera in different regions of the country, 
we will be able to make predictions about over- 
all insect — and therefore biological — diversity, 
and about relationships between plant and 
insect species richness on a local or regional 
basis. Such knowledge will lead to more effi- 
cient methods of assessing the health and loss of 
biological diversity. 

Once a baseline inventory is done, monitor- 
ing of changes in species richness and abun- 
dance to assess the ecological health of the 
community can be carried out. Inventory of a 
diverse group of insects such as the Lepidoptera 
must involve various approaches and collecting 
procedures. This article summarizes the status 
of local and state inventories of Lepidoptera and 
suggests a model for planning comparable fau- 
nal inventories of major insect groups. 

Lepidoptera Surveys 

To gather information on the status of cur- 
rent inventories, I mailed a one-page question- 
naire to 25 lepidopterists thought to be develop- 
ing local or state lists. Nearly all responded, and 
several are conducting more than one census. 
Early in 1993 I published a request for informa- 
tion on inventories in the News of The 



Lepidopterists ' Society, which is distributed to 
about 1,000 members in North America. The 
responses were fewer than I had expected; there 
may be many more inventories in progress than 
those reported to me. For completed local and 
state lists, I searched the literature, but the 
results are likely to be incomplete because such 
lists are lengthy and often are published in 
obscure literature not well referenced by 
abstracting services. 

A thorough local inventory must depend 
upon diverse methods: daytime searches for 
butterflies and diurnal moths, nighttime collec- 
tions of moths attracted to ultraviolet (UV) or 
mercury vapor lights, and rearing caterpillars 
(larvae) to the adult stage. In some regions a 
fourth approach, "sugaring," the attraction of 
moths to sweet, fermenting bait, is effective for 
many species not readily attracted to lights. 
Generating an inventory for a large group of 
insects such as Lepidoptera is difficult because 
the season that each species can be found may 
be short; species abundance varies widely from 
year to year; several techniques and specialists' 
experience are needed to complete a thorough 
census; and, beginning early in the survey, indi- 
viduals of vagrant species are encountered. 

A major problem in compiling an inventory 
is the identification of species. This is easily 
accomplished for butterflies (6% of the 
Lepidoptera), and there are hundreds of local 
and state lists (Field et al. 1974). Identifications 
are accessible for the larger moths (macrolepi- 
doptera), including inchworm moths 
(Geometridae), giant silkworm moths 
(Satumiidae), hawk moths (Sphingidae), owlet 
moths (Noctuidae). and related families. 
However, for many so-called "microlepi- 
doptera" (primitive suborders, leaf miner and 
leaf roller moths, etc.), 10%-90% of the local 
species in some families are undescribed. As a 
result, most state and local lists have dealt only 
with macrolepidoptera or have treated the 
microlepidoptera species only cursorily. 

Inventories and Trends 

There are published Lepidoptera lists or sur- 
veys in progress from at least 30 states, and 



Our Living Resources — Invertebrates 



169 



local inventories of at least raacrolepidoptera 
for 35 or more reserves, counties, or islands in 
the continental United States. The tendency of 
lepidopterists to compile state and local lists, 
which had been expressed primarily by faunal 
studies of butterflies (Field et al. 1974), increas- 
ingly has encompassed moths. Half of the state 
lists and 85% of the local inventories have been 
published since 1964, and there are an even 
larger number in progress. More of these 
include microlepidoptera than before probably 
because of considerable progress in the descrip- 
tive taxonomy of most families during the past 
35 years (e.g., Covell 1984). 

State Lists 

The older and more comprehensive state lists 
are in the eastern United States (Fig.l). The 
most complete state lists of Lepidoptera are 
those for New York (Forbes 1923-60), New 
Jersey (Smith 1910; Muller 1965-76), and 
Maine (Brower 1974-86), although these lists 
have many identification problems. The most 
active are in Ohio, Kentucky, Mississippi, 
Florida (Kimball 1965), and Texas. There are 
lists primarily or only of macrolepidoptera for 
some states, including Arizona (Bailowitz et al. 
1990), Michigan (Moore 1955), Pennsylvania 
(Tietz 1952), and Maryland (D.C. Ferguson et 
al., National Museum of Natural History, 
unpublished data). Lists of described species for 
the western states are now being done (Fig. 1). 

Local Inventories 

Thirty-five local inventories have been pub- 
lished or are in progress (Fig. 1). These vary 
greatly in moth families included, geographic 
size, and number of years in progress. Several 
inventories, including those of Martha's 
Vineyard and Nantucket, Massachusetts (Jones 
and Kimball 1943); Mount Desert Island, 
Maine (Proctor 1946); Welder Wildlife Refuge, 
Texas (Blanchard et al. 1985); Ash Canyon, 
Arizona (N. McFarland, Sierra Vista, AZ, 
unpublished data); and three in California 
(McFarland 1965; Powell, unpublished data) 
span 10-50 years and are estimated to be 85%- 
95% complete (Table). 

Unfortunately, no two inventories can be 
meaningfully compared because they vary in 
important parameters. Many have recorded only 
macrolepidoptera, often only one sampling 
approach was emphasized, inventories are made 
of sites that vary greatly in size, inventory dura- 
tion ranges considerably (Table), and the meth- 
ods of recording data are often inconsistent. 

A Model Inventory 

We have been conducting inventories in 
California to document species discovery rates 




o Inventories of single sites 
■ Comprehensive lists 
□ Macrolepidoptera lists 
Preliminary lists in progress 



and other comparative data. The most compre- 
hensive inventory is at the University of 
California Big Creek Reserve in coastal 
Monterey County, an area of diverse habitats 
and elevations. The census has been carried out 
primarily by specialists' visits. We have sam- 
pled in all months, on 175 dates, recording 
every species in each sample; we spent 180 per- 
sonnel-days for diurnal species, recorded more 
than 260 UV light samples, and processed 1,350 
larval collections and their rearing. The census 
(more than 900 species) is believed more than 
90% complete, with 3% or fewer of the species 
in each three-date sample new to the list during 
dates 155-175 (Fig. 2). Butterflies and diurnal 
moths make up 16% of the total, and microlepi- 
doptera recorded only as larvae make up anoth- 
er 9%. 

The species discovery rate was slow because 
we could not sample the whole reserve during 
each visit, and most of the effort followed a 
consummate fire in the fourth year of our 12- 
year inventory; many species were first collect- 
ed in year 9 or 10. Nevertheless, the results pro- 
vide a realistic idea of the effort required in a 
complex community to achieve a reliable 
species accumulation curve (Fig. 2). 



State* 


Area (km 2 ) 


Duration 
(years) 


% est. 
censused 


No. of 
species 


Arizona macro 


<10 


13 


>95 


900 + 


California macro 


<10 


10 


>95 


278 


California micro 


<10 


25 


80-85 


160 


California micro 


16 


12 


85-90 


376 


Florida macro 


<10 


2 


80-90 


318 


Illinois micro 


200 


50 


90-95 


945 


Maine macro 


<10 


4 


<70 


349 


New Jersey macro 


<10 


5 


90 


410 


New York macro 


100 


30 + 


>95 


872 


Oregon macro 


<10 


1.5 


70-80 


360 


Texas macro 


30 


24 + 


50-70 ? 


481 


West Virginia macro 


<10 


6 


90 


400 



Fig. 1. Distribution of state and 
local inventories of Lepidoptera in 
the contiguous 48 United States. 
States having comprehensive lists 
(all families) published or in 
progress, those with macrolepi- 
doptera lists, and those with pre- 
liminary lists in progress are indi- 
cated. Dots indicate locations of 
35 local inventories of single sites, 
reserves, and islands, either pub- 
lished or in progress. 



Table. Comparison of size, dura- 
tion, estimated percentage com- 
pleted, and numbers of species 
recorded in local inventories of 
Lepidoptera, listed by state. 



" Macro — macrolepidoptera 
Micro — microlepidoptera 



170 



Invertebrates — Our Living Resources 



Fig. 2. Species discovery curve 
for all Lepidoptera at the Big 
Creek Reserve. Monterey County. 
California, based on collections 
during 1980-93. The total (910 
species) is believed to be more 
than 90% of the resident fauna. 
Points along the curve are indicat- 
ed when 50%, 67%, 75%, and 
90% of the recorded total were 
reached. 



1,000 




For further information: 

Jerry A. Powell 

Essig Museum of Entomology 

University of California, Berkeley 

201 Wellman Hall 

Berkeley, CA 94720 



20 40 60 80 100 120 140 160 180 
No. of dates 



The data from Big Creek and other invento- 
ries (e.g., Butler and Kondo 1991) demonstrate 
that short-term effort is inadequate to inventory 
insects. We cannot determine faunal composi- 
tion from a few visits to a site or even compre- 
hensive sampling over one season. If a group 
under study is relatively uniform in biology, one 
sampling or trapping technique may be ade- 
quate and a steeper species accumulation curve 
can be attained. At Big Creek, all Lepidoptera 
accumulation did not reach 50% until 25 dates, 
or 75% until 65 dates (Fig. 2). 

Planning Inventories 

A comprehensive inventory should employ 
diverse sampling approaches, as outlined previ- 
ously. Light trapping alone may be expected to 
recover about 75% of the species after extended 
effort. If monitoring changes in populations is a 
goal, a subset of the fauna (e.g., one or a few 
well-known families) should be the focus, with 
sampling standardized by method (e.g., light 
trap), site, frequency, and so forth, so as to be 
repeatable. To make local inventories compara- 
ble, data should be identified in several ways: 
(1) results should be recorded by standardized 
subsets of the area; (2) sampling effort should 
be quantified and reported (e.g., number of per- 
son-hours or days, dates, UV samples); (3) first 
records for each species should be recorded to 
document species discovery rates; (4) voucher 
specimens should be preserved, especially for 
small moths, because detailed study by a spe- 
cialist may be necessary to distinguish species. 
Ideally, every specimen can be bar-coded to the 
data base, a rapid process if carried out in tan- 
dem with data entry initially as is being done in 
Costa Rica (Janzen 1992). 

We do not know how many species of moths 
and butterflies live in any state, county, or local- 



ity in North America. We need baseline inven- 
tories that are standardized by area or sampling 
effort by which different parts of the continent 
or tropical faunas can be compared to extrapo- 
late patterns in regional, national, or world bio- 
diversity of Lepidoptera. 

References 

Bailowitz, R.A. et al. 1990. A checklist of the Lepidoptera 
of Arizona. Utahensis 10:13-32. 

Blanchard. A. et al. 1985. Checklist of Lepidoptera of the 
Rob and Bessie Welder Wildlife Refuge near Sinton, 
Texas. The Southwestern Entomologist 10:195-214. 

Brower, A.E. 1974-86. A list of the Lepidoptera of Maine. 
Parts 1. 2. Maine Agricultural Experiment Station. Tech. 
Bull. 66:1-136; 109:1-60; 114:1-70. 

Butler, L., and V. Kondo 1991. Macrolepidopterous moths 
collected by blacklight trap at Cooper's Rock State 
Forest, West Virginia: a baseline study. Agriculture and 
Forestry Experiment Station. West Virginia University, 
Bull. 705:1-25. 

Covell, C.V. 1984. A guide to the moths of eastern North 
America. Houghton-Mifflin Co., Boston, MA. 496 pp. 

Field, W.D., C.F. dos Passos, and J.H. Masters. 1974. A bib- 
liography of the catalogs, lists, faunal and other papers 
on the butterflies of North America north of Mexico 
arranged by state and province (Lepidoptera: 
Rhopalocera). Smithsonian Contributions to Zoology 
157:1-104. 

Forbes, W.T.M. 1923-60. Lepidoptera of New York and 
neighboring states, I-IV. Cornell University Agricultural 
Experiment Station Memoirs 68:1-729: 274:1-263: 
329:1-433:371:1-188. 

Janzen, D.H. 1992. Information on the bar code system that 
INBio uses in Costa Rica. Insect Coll. News 7:24. 

Jones, F.M., and C.P. Kimball. 1943. The Lepidoptera of 
Nantucket and Martha's Vineyard. Publ. Nantucket 
Maria Mitchell Assoc. 4:1-21 7. 

Kimball, C.P. 1965. The Lepidoptera of Florida. Division of 
Plant Industry, Florida Department of Agriculture. 
Gainesville. 363 pp. 

McFarland, N. 1965. The moths (Macroheterocera) of a 
chaparral plant association in the Santa Monica 
Mountains of southern California. Journal of Res. on 
Lepidoptera 4:43-74. 

Moore, S. 1955. An annotated list of the moths of Michigan, 
exclusive of Tineoidea (Lepidoptera). Museum of 
Zoology, University of Michigan, Ann Arbor. 
Miscellaneous Publ. 88:1-87. 

Muller. J. 1965-76. Supplemental list of Macrolepidoptera 
of New Jersey. Journal of the New York Entomological 
Society 73:63-77: 76:303-306: 81:66-71; 84:1 97-20L 

Proctor. W. 1946. Biological survey of the Mount Desert 
region. Part VII. The insect fauna. Wistar Institute of 
Anatomy and Biology. Philadelphia. PA. 566 pp. 

Smith. J.B. 1910. Report of the New Jersey State Museum 
for 1909. Trenton, NJ. 887 pp. 

Tietz. H.M. 1952. Lepidoptera of Pennsylvania. A manual. 
Pennsylvania State College. Agricultural Experiment 
Station. State College. PA. 194 pp. 



Our Living Resources — Invertebrates 



171 



The Xerces Society started the Fourth of July 
Butterfly Count (FJC) in 1975, sponsoring 
it annually until 1993, when the North 
American Butterfly Association (NABA) 
assumed administration. The general methods 
of the butterfly count are patterned after the 
highly successful Christmas Bird Count (CBC), 
founded in 1900 and sponsored by the National 
Audubon Society (Swengel 1990). 




Painted lady (Vanessa cardui) nectaring on showy milk- 
weed (Asclepias speciosa). 

The results of the FJC, including butterfly 
data, count-site descriptions, and weather infor- 
mation on count day, are published annually. 
The count was designed as an informal program 
for butterfly enthusiasts and the general public. 
These counts can never substitute for more for- 
mal scientific censusing because data sets from 
the counts have flaws that impair scientific 
analysis. Nevertheless, the FJC program does 
provide data that, with considerable caution, 
can be useful for science and conservation 
(Swengel 1990). FJC data have been used to 
study the biology, status, and trends of both rare 
and widely distributed species (Swengel 1990; 
Nagel et al. 1991; Nagel 1992; Swengel, unpub- 
lished data). 

Analysis and Application 

I reviewed FJC count reports and other pub- 
lications for applications of FJC data to monitor 
the status and trends of North American butter- 
fly species. These studies varied considerably in 
sample size, amount of data manipulation and 
statistical analysis, and degree of variable con- 
trol. Different methods of using FJC data 
include, in order of ascending statistical refine- 
ment: presence or absence of a species in a sub- 
set of counts; highest observed number of a 
species on a single count; individuals of a 
species per count for a subset of counts in a 
given year; and individuals of a species per 
count hours or per count miles. The subset of 
counts used to supply data for analysis also var- 
ied from a single count to all counts in a certain 
region or all counts ever reporting a given 



species during the study period. The sample sub- 
set and statistical approach are best determined 
by the nature and extent of available data. 

The rationales, methodologies, shortcom- 
ings, and validity of analyzing FJC data have 
been detailed elsewhere (Swengel 1990), but 
are based on the substantial ornithological liter- 
ature regarding the scientific use of CBC and 
other types of survey data. As ornithologists 
have clearly indicated, these kinds of data sets 
must be used with great care because (1) the 
sample sites and dates depend on when and 
where volunteer observers choose to conduct a 
count; (2) the quality of sampling and accuracy 
of data vary among counts; (3) only certain 
species are sampled adequately enough to allow 
data interpretation; and (4) the species complex 
can vary somewhat from year to year. Even with 
such constraints, these data sets are valuable 
because of the numerous sites surveyed, their 
wide geographic scope, and the relatively low 
cost of data acquisition. 

Interpreting Count Data 

For the first 1 1 years of the count program 
(1975-85), only a few dozen counts were held 
annually, but since then the number of annual 
counts has increased steadily to 209 in North 
America in 1993. Each FJC annual report since 
1982 has provided a table that details how many 
counts reported each species and which single 
count found the most individuals of each 
species. Although informal, this table indicates 
the frequency and abundance of butterfly 
species as observed in the counts. 

Several rare species with federal status under 
the Endangered Species Act have been sampled 
in the counts, as reviewed in the introduction to 
the 1993 FJC annual report (Opler and Swengel 
1994). A researcher using FJC to study rare but- 
terflies must be careful in interpreting the data, 
however. Unless a number of FJC counts are 
specifically designed to sample rare species 
well, it is unlikely that rare species will be sam- 
pled adequately enough to allow scientific 
analysis of status and trends. Even in these 
cases, however, site data for rare species report- 
ed in FJC remain useful as leads to follow in 
status surveys of extant populations for these 
species (Opler and Swengel 1994). Most likely, 
the data should be considered as augmenting 
additional, more formal scientific study and 
should be confirmed, either by alternative sur- 
vey means or by contacting the counters for 
documentation. 

Because of the larger sample size, FJC data 
may better demonstrate the population trends of 
more abundant and widespread species. For 
example, the painted lady (Vanessa cardui) is a 



Fourth of July 

Butterfly 

Count 



by 

Ann B. Swengel 
International Count Co-editor 




Monarch (Danaus plexippus) nec- 
taring on dwarf blazingstar (Liatris 
cylindracea). 



172 



Invertebrates — Our Living Resources 



% counts 




75 77 79 81 83 85 87 89 91 93 95 
Year 

Fig. 1. Number of painted ladies 
{Vanessa cardui) per count and 
percentage of counts reporting this 
species, for all counts in North 
America north of Mexico, 
1977-93. 




77 79 81 83 85 87 89 91 93 
Year 

Fig. 2. Mean number of mon- 
archs (Danaus plexippus) per 
party-hour for counts reporting the 
species east of the Rocky 
Mountains, 1977-93, and west of 
the Rocky Mountains, 1987-93. 

For further information: 

Ann B. Swengel 

North American Butterfly 

Association 

909 Birch St. 

Baraboo.WI 53913 



subtropical species with a tendency to wander 
(immigrate) outside its residential range into 
temperate regions, with periodic years of mas- 
sive invasions. FJC data clearly reflect this 
aspect of the species' natural history by show- 
ing dramatic fluctuations in painted lady fre- 
quency and abundance in the counts in 1979, 
1983, and 1992 (Swengel 1993; Fig. 1). These 
outbreaks may correlate with weather perturba- 
tions in the species' residential range (Myres 
1985; Swengel 1993). 

FJC data have also been used to document 
fluctuations in other immigrant species 
(Swengel 1990), but especially to monitor pop- 
ulation trends of the migrant monarch butterfly 
(Danaus plexippus; Swengel 1990 and unpub- 
lished data) that breeds in temperate North 
America and overwinters in Mexico and coastal 
California. The number of these butterflies fluc- 
tuates considerably (Fig. 2); fluctuations tend to 
correlate with major climatic perturbations such 
as the El Nino Southern Oscillation and major 
volcanic eruptions (Swengel, unpublished 
data). Monarchs and painted ladies often show 
dramatic fluctuations in the same years (e.g., 
1978-79, 1982-83, 1991-92), but usually they 
vary in opposite directions (Figs. 1 and 2), sug- 
gesting that the same widespread climatic phe- 
nomena tend to affect both species in different 
ways. Because conservationists are concerned 
about threats to the overwintering habitat of 
monarchs, long-term data sets such as FJC are 
valuable to check for persistent downward 
trends. 

While FJC cannot replace more formal and 
intensive scientific surveying, it does offer a 




Karner blue (Lycaeides melissa samuelis) male basking on 
grass. 

readily available and ever-enlarging data set that, 
with caution, is useful for science and conserva- 
tion because of its relative continuity, inexpen- 
siveness, large size, and widespread sampling. 

References 

Myres, M.T. 1985. A southward return migration of painted 
lady butterflies. Vanessa cardui. over southern Alberta in 
the fall of 1983, and biometeorological aspects of their 
outbreaks into North America and Europe. The Canadian 
Field-Naturalist 99:147-155. 

Nagel. H. 1992. The link between Platte River flows and the 
regal fritillary butterfly. The Braided River 4:10-1 1. 

Nagel. H.G., T. Nightengale, and N. Dankert. 1991. Regal 
fritillary butterfly population estimation and natural his- 
tory on Rowe Sanctuary, Nebraska. Prairie Naturalist 
23:145-152. 

Opler, P.A.. and A.B. Swengel. 1994. NABA-Xerces Fourth 
of July butterfly counts 1993 report. North American 
Butterfly Association. Morristown, N.I. 72 pp. 

Swengel, A.B. 1990. Monitoring butterfly populations using 
the 4th of July butterfly count. American Midland 
Naturalist 124:395-406. 

Swengel. A. 1993. Permutations of painted ladies. American 
Butterfliesl(2):34. 



Species 
Richness and 
Trends of 
Western 
Butterflies and 
Moths 

by 

Paul A. Opler 

National Biological Service 



Butterflies and large moths are among the 
best-sampled insects and as such are excel- 
lent indicators of ecological conditions or envi- 
ronmental change. Because the caterpillars of 
most Lepidoptera are herbivorous, their species 
richness is most often a reflection of plant diver- 
sity (Brown and Opler 1990). 

Management or restoration of invertebrate 
diversity requires comprehensive data about the 
status and occurrence of species. I present the 
species richness of butterflies and three moth 
families in the 17 western conterminous states 
and five smaller subareas in the West. 

Data Collection 

The species richness of western butterflies 
and moths (Lepidoptera) was determined by 
using four county-level atlases and counting the 
number of species recorded in each state or 
region (Peigler and Opler 1993; Smith 1993; 
Stanford and Opler 1993; Opler, unpublished 



data). The county atlases were developed by 
using specimen data from field surveys, private 
collections, museums, and scientific mono- 
graphs. The records analyzed include all histor- 
ical data; thus the map for a particular species 
may not represent its current status. 

Butterflies (superfamilies Papilionoidea and 
Hesperioidea), hawkmoths (Sphingidae), silk- 
moths (Satumiidae), and tiger moths (Arctiidae) 
are relatively well-sampled groups and therefore 
give a good preliminary indication of the geo- 
graphic patterns of species richness. Populations 
of the selected butterflies and moths in the 17 
conterminous western states and five subregions 
were selected as sampling units. 

The five subregions are the lower Rio 
Grande Valley of South Texas, the Big Bend 
region of Texas, the Colorado Front Range, the 
isolated mountains of southeastern Arizona and 
adjacent New Mexico (the so-called "sky 
islands"), and southern California south of the 
Transverse Ranges (Fig. 1). They were selected 



Our Living Resources — Invertebrates 



173 



based on a priori knowledge of species richness 
and patterns of endemic species occurrence. 

The number of resident butterflies was deter- 
mined by counting the number of species 
recorded for each state or region. Species 
known to be nonresidents (vagrants or sporadic 
residents) in a particular state or region were 
excluded. For the three moth families, all 
species recorded in a particular state or region, 
including vagrants, were included in the counts. 

The reader should be aware that the quantity 
and quality of the data are not sufficient to ana- 
lyze temporal trends for individual species. In 
addition, all geographic units have not been 
sampled with equal intensity. 

Status and Trends 

In the 17 western states, 915 species of but- 
terflies and moths in the studied groups are 
recorded. The number of species ranges from 
181 (20% of total species count) for North 
Dakota to 520 (57% of total species count) for 
Texas (Table 1). In general, there are fewer 
species of butterflies and moths in more north- 
ern states and in states with less topographic 
diversity, which creates less variety in terrain. 
Of course, larger states tend to have more 
species than smaller states, since large states, on 
average, have more diverse habitats and topog- 
raphy. These trends are similar to those of other 
organisms as well. 

The patterns for butterflies and the three 
moth families are similar, except that species 
richness of hawkmoths is unexpectedly high in 
Nebraska and Oklahoma (Table 1), most likely 
because of the immigration of nonbreeding 
tropical species (Smith 1993). 

Each of the five subregions is smaller than 
Washington, the smallest western state, yet 
species richness is greater in all subregions 
(except the Lower Rio Grande) than in nearly 

Table 1. Number of species of selected Lepidoptera by 
state. 



State 



Area 
km 2 (mi 2 ) 



Hawk- 
moths 



Silk- Tiger Butter- 
moths moths flies 



Total 



Arizona 


294.0(113.5) 


49 


31 


111 


246 


437 


California 


404.8(156.2) 


30 


17 


52 


225 


324 


Colorado 


268.3(103.6) 


32 


18 


71 


230 


351 


Idaho 


210.9(81.4) 


16 


7 


24 


154 


201 


Kansas 


211.9(81.8) 


23 


9 


34 


133 


199 


Montana 


376.6(145.4) 


10 


6 


27 


184 


227 


Nebraska 


198.4 (76.6) 


36 


10 


38 


170 


254 


Nevada 


284.6 (109.9) 


18 


9 


28 


181 


236 


New Mexico 


314.2(121.3) 


31 


24 


83 


272 


410 


North Dakota 


179.5 (69.3) 


30 


3 


16 


132 


181 


Oklahoma 


177.9(68.7) 


39 


13 


30 


146 


228 


Oregon 


249.2 (96.2) 


23 


9 


28 


154 


214 


South Dakota 


196.6(75.9) 


12 


7 


32 


149 


200 


Texas 


678.6(261.9) 


69 


34 


127 


290 


520 


Utah 


212.6(82.1) 


24 


14 


46 


197 


281 


Washington 


172.2 (66.5) 


17 


8 


27 


140 


192 


Wyoming 


251.2 (97.0) 


18 


7 


49 


197 


271 


Totals for western U.S. 


4,681.5(1,807.1 


99 


68 


219 


529 


915 



two-thirds (11 out of 17) of the states studied 
(Table 2). The richest subregion, with 273 
species, is the sky islands of southeastern 
Arizona and southwestern New Mexico. 
Species richness is second highest in the Front 
Range of Colorado, which straddles the 
Continental Divide and includes a large eleva- 
tional range and diverse habitats ranging from 
prairie to alpine tundra. The relatively small 
Lower Rio Grande Valley has the fewest species 
of the five subregions, but still has more species 
than some states that are almost 15 times as 
large. Moreover, the best remaining native 
habitats in this subregion amount to only a few 
thousand hectares. Sampling intensity is rela- 
tively high for the Front Range, sky islands, and 
southern California, but increased sampling 
efforts in the Lower Rio Grande Valley and Big 
Bend might add significant numbers of species. 
Each subregion has a distinct butterfly and 
moth fauna that includes many endemics — 20 
or more are potential candidates for listing as 
endangered species. Each of the four subregions 
that adjoin the Mexican border also hosts from 
a few to many Mexican species that occur 
nowhere else in the United States. 

~ j Alea Hawk- Silk- Tiger Butter- T . 
9 km 2 (mi 2 ) moths moths moths Hies 



Lower Rio Grande 3 


14.0 (5.4) 


33 


11 


11 


115 


170 


Big Bend b 


37.3(14.4) 


28 


10 


10 


151 


199 


Front Range c 


71.5(27.6) 


26 


11 


11 


176 


224 


Sky islands d 


41.4(16.0) 


41 


25 


25 


182 


273 


Southern California 6 


116.6(45.0) 


23 


14 


33 


159 


229 



a Lower Rio Grande Valley includes all of Cameron, Hidalgo, Willacy, and 

Starr counties, TX. 

b Big Bend includes all of Brewster, Jeff Davis, and Presidio counties, TX . 

c The Colorado Front Range includes all of Boulder, Clear Creek, Custer, 

Douglas, El Paso, Fremont, Gilpin, Grand, Huerfano, Jackson, 

Jefferson, Larimer, Park, Pueblo, Summit, and Teller counties. 

d Sky islands include all of Cochise and Santa Cruz counties, the eastern 

half of Pima County, AZ, and all of Hidalgo County, NM. 

e Southern California includes all of Imperial, Los Angeles, Orange, 

Riverside, San Bernardino, and San Diego counties. 

The highest species richness of western 
Lepidoptera is in the Southwest, usually in 
areas that adjoin the Mexican border. 
Invertebrates are seldom considered in manage- 
ment plans for parks, preserves, or refuges, and 
their management needs are often not the same 
as those for vertebrate wildlife or plants. 
Processes unfavorable to Lepidoptera diversity 
include overgrazing, overuse of controlled 
burns, urbanization, and excessive modification 
or recreational use of selected specialized 
ecosystems such as wetlands and dunes. 
Because invertebrates account for more than 
90% of animal species, it makes good sense for 
managers to address the health and populations 
of these species in planning and in making man- 
agement decisions. Management which favors 
high Lepidoptera species richness is usually 
similar to that which favors natural ecosystem 
processes and the maintenance of extensive 
native plant populations. 




1 . Lower Rio Grande Valley, Texas 

2. Big Bend, Texas 

3. Front Range, Colorado 

4. Sky islands, Arizona and New Mexico 

5. Southern California 

Fig. 1. Western United States 
showing five subregions of high 
species richness. 



Table 2. Number of species of 
selected Lepidoptera by subregion. 




Two tailed swallow-tail (Papilio 
multicaudata). 




Tiger moth (Gnophaela vermicula- 
ta). 



174 



Invertebrates — Our Living Resources 



For further information: 

Paul A. Opler 

National Biological Service 

Information Transfer Center 

1201 Oak Ridge Dr. 

Suite 200 

Fort Collins, CO 80525 



References 

Brown, J.W.. and P. A. Opler, 1990. Patterns of butterfly 
species density in peninsular Florida. Journal of 
Biogeography 17:615-622. 

Peigler, R.S., and PA. Opler. 1993. Moths of western North 
America. 1. Distribution of Satumiidae of western North 
America. Contributions of the C.P Gillette Insect 
Biodiversity Museum. Colorado State University, Fort 
Collins. 24 pp. 

Smith, M.J. 1993. Moths of western North America. 2. 
Distribution of Sphingidae of western North America. 
Contributions of the C.P. Gillette Insect Biodiversity 
Museum, Colorado State University, Fort Collins. 34 pp. 

Stanford. R.E., and PA. Opler. 1993. Atlas of western USA 
butterflies, including adjacent parts of Canada and 
Mexico. Published by authors, Denver, CO. 275 pp. 




Sphinx moth (Proserpinus juanita 



The Tall-grass 
Prairie 
Butterfly 
Community 



by 

Ann B. Swengel 

Scott R. Swengel 

Baraboo, Wisconsin 




■ Study sites T 1 Tall-grass prairie biome 

Fig. 1. Original boundaries of the 
tall-grass prairie biome in the 
United States ( Kisser et al. 1981) 
and locations of study sites (A.B. 
Swengel, unpublished data). 



The prairie biome is a plant community dom- 
inated by grasses and nongrassy herbs 
(wildflowers or "forbs"), with some woody 
shrubs and occasional trees. Prairie is classified 
into three major types by rainfall and conse- 
quent grass composition. The easternmost and 
moistest division is the tall-grass prairie (Risser 
et al. 1981). Although tall-grass prairie once 
broadly covered the middle of the United States 
(Fig. 1), this biome is now estimated to be at 
least 99% destroyed from presettlement by pio- 
neers, who converted it for agricultural uses. 
Prairie loss continues through plowing, extreme 
overgrazing, and development, but at varying 
degrees. Prairie is also lost passively because 
the near-total disruption of previous ecological 
processes causes shifts in floristic composition 
and structure. 

As a result of this habitat destruction, butter- 
flies and other plants and animals that are oblig- 
ate to the prairie ecosystem are rare and primar- 
ily restricted to prairie preserves. The Dakota 
skipper (Hesperia dacotae) and the regal fritil- 
lary (Speyeria idalia) are federal candidates for 
listing under the Endangered Species Act, and 
additional prairie butterfly species are on state 
lists as officially threatened or endangered. 
Patches of original prairie vegetation remain in 
preserves, parks, unintensively used farmlands 
such as hayfields and pastures, and in unused 
land. These remnants of prairie, however, are 
isolated and often in some state of ecological 
degradation. 

The existence of prairie depends on the 
occurrence of certain climatic conditions and 
disturbance processes such as animal herbivory 
and fire. These natural processes, however, are 
severely disrupted today because of the destruc- 
tion and fragmentation of the prairie biome. 
Without management intervention, the vegeta- 
tional composition and structure of prairie sites 
are altered through invasion of woody species 
and smothering under dead plant matter. Prairie 
usually requires active management to main- 
tain the ecosystem and its biodiversity, but it is 



difficult to know exactly which processes once 
naturally maintained the prairie ecosystem. 
Frequent fire, whether caused by lightning or 
set by native peoples, is usually considered the 
dominant prehistoric process that maintained 
prairie; thus management for tall-grass prairie 
in most states relies primarily or solely on fre- 
quent fire (e.g., Sauer 1950; Hulbert 1973; Vogl 
1974). Other researchers (e.g., England and 
DeVos 1969), however, assert that prairie was 
the result of grazing by large herds of ungulates 
as in the Serengeti in Africa. 

Despite this scientific conflict, it appears 
certain that successful management for main- 
taining the prairie landscape and its native 
species should be based on these natural 
processes, whatever they were. The vast diversi- 
ty and specificity of insects to certain plants and 
habitat features make them fine-tuned ecologi- 
cal indicators. Thus, butterfly conservation is 
useful not only for maintaining these unique 
species, but also for helping us monitor and 
learn about the soundness of our general 
ecosystem management. 

Survey and Classification 

We counted 90 butterfly species and 80,906 
individuals in surveys from 1988 to 1993 at 93 
prairies varying from 1 to 445 ha (3 to 1,100 
acres) in the Upper Midwest (Illinois, Iowa. 
Minnesota, Wisconsin) and southwestern 
Missouri (Fig. 1 ). Most sites are managed prin- 
cipally with fire, with burns averaging about 
25% (range 0-99% or more) of the prairie patch 
per year. Many Missouri sites are managed pri- 
marily with summer haying along with a little 
burning and cattle grazing. The vegetation in 
each survey unit was relatively uniform. 

Any species observed 100 or more times was 
designated a study species. Before analyzing 
the results, we classified the study species by 
habitat niche breadth: prairie specialist, grass- 
land, generalise and invader. We used popula- 
tion indices (individuals observed per hr in each 



Our Living Resources — Invertebrates 



175 



unit) to identify which units had relatively 
greater densities of particular species and which 
factors might account for this variation. Details 
regarding the survey and statistical methodolo- 
gies are provided elsewhere (A.B. Swengel, 
unpublished data). 

Management and Distribution 

The overwhelming destruction of prairie 
habitat has had disastrous consequences for 
prairie-specialist butterflies, not just because of 
the outright loss of appropriate living space but 
also because of habitat fragmentation. Because 
prairie-specialist butterflies are rarely encoun- 
tered outside of these fragmented prairie patch- 
es, populations at different sites may have min- 
imal gene flow and are rarely able to recolonize 
sites of local extinctions. For example, the regal 
fritillary is the most widespread prairie butterfly 
species, but it requires larger habitat patches or 
connected networks of habitat patches to main- 
tain populations. The arogos skipper (Atrytone 
arogos iowa) and ottoe skipper (Hesperia ottoe) 
also occur widely in the prairie biome but are 
more restricted in their habitat requirements, 
resulting in more localized and spotty distribu- 
tions. The Dakota skipper and poweshiek skip- 
per (Oarisma poweshiek) are most restricted in 
range, occurring only in northern prairie, and 
have further habitat restrictions within that 
range. As a result, the northern Midwest (north- 
western Iowa, western Minnesota, and the east- 
ern Dakotas) is the region where tall-grass 
prairie conservation has the most potential for 
maintaining the greatest diversity of prairie-spe- 
cialist butterflies. 




Regal fritillaries (Speyeria idalia) mating on pale purple 
coneflower (Echinacea pallida). 



Our surveys show that the management 
occurring at a prairie critically affects whether 
prairie-specialist butterflies exist at the site and 
at what abundance. Although each butterfly 
species has its own response to fire, the prairie 
specialists show a pronounced and statistically 
significant decline after fire; this decline per- 
sists 4 or more years (A.B. Swengel, unpub- 
lished data). Species with the broadest habitat 
adaptation (invaders) are most abundant in 
recently burned units and least abundant in units 
left unburned the longest. Species of intermedi- 
ate adaptations (grasslands, generalists) showed 
milder, intermediate trends. 

Unintensive haying management (a single 
annual or biennial cutting with removal of the 
clipped vegetation) is more favorable for butter- 
fly diversity. Such haying is more beneficial for 
butterflies sooner after treatment and causes a 
less pronounced variation in butterfly abun- 
dance between different treatment years. In 
general, butterflies are more abundant in the 
first years after haying than after burning; spe- 
cialists account for much of this difference (Fig. 
2). Our limited opportunities to test light graz- 
ing show that it may also serve specialist butter- 
flies better than fire. 

Prairie-specialist butterflies apparently 
respond to different management types because 
of varying degrees of mortality (e.g., fire causes 
more direct mortality than haying or grazing) 
and because of differences in continuity of 
required habitat resources (e.g., fire removes all 
cover but is followed by regrowth of thick 
cover, while unintensive haying and grazing can 
more consistently maintain moderate cover). 
Management also indirectly affects butterfly 
populations by altering the abundance and 
occurrence of plants they depend on as well as 
the vegetational structure and physical features 
they require. 

These results are consistent with butterfly 
conservation experience around the world, par- 
ticularly in Europe and Australia (Butterflies 
Under Threat Team 1986; Kirby 1992; New 
1993). Thus, simply preserving habitat is not 
sufficient to conserve insect biodiversity; suit- 
able management approaches and land uses 
compatible with the habitat's native biodiversi- 
ty must be preserved. It is possible to maintain 
plants successfully without protecting the asso- 
ciated animals, but it is impossible to maintain 
the associated animals successfully without 
protecting the plants. 

It appears desirable for managers to aim for 
diversity and patchiness in prairie-management 
approaches within and among sites rather than 
broadly applying a single management formula 
for prairie everywhere. Whether or not a site is 
managed specifically to conserve insects, 
declines and extirpations of insects specialized 



140 



=sioo 



■ burn-year 
D burn-year 1 

■ hay-year 
M hay-year 1 




All Nonspecialist Specialist 

Fig. 2. Abundance of all, nonspe- 
cialist (grassland, generalists, and 
invaders), and prairie-specialist 
study species in the first years of 
fire and hay management, 
Missouri study sites. 



776 



Invertebrates — Our Living Resources 



For further information: 

Ann B. Swengel 

909 Birch St. 

Baraboo, WI 53913 



to the habitat indicate that ecological degrada- 
tion has already occurred there, while mainte- 
nance of these species indicates success in 
ecosystem conservation. Because we found that 
management with mechanical cutting or light 
grazing appears most effective for maintaining 
both the prairie habitat and its associated spe- 
cialist insects (seeming to indicate an ecosys- 
tem adaptation to herbivory), we recommend 
that these methods should have a primary role 
in modern prairie management for the conser- 
vation of biodiversity. There is cause for opti- 
mism, however, because no known prairie but- 
terfly species have gone extinct, despite their 
rarity. Instead, these species have persisted on 
habitat remnants, showing that appropriate 
habitat preservation and management should 
translate into readily measurable conservation 
successes. 



References 

Butterflies Under Threat Team. 1986. The management of 
chalk grassland for butterflies. Joint Nature Conservation 
Committee. Peterborough, U.K. 80 pp. 

England, R.E., and A. DeVos. 1969. Influence of animals on 
pristine conditions on the Canadian grasslands. Journal of 
Range Management 22:87-94. 

Hulbert, L.C. 1973. Management of Konza Prairie to approx- 
imate pre-whiteman influences. Pages 14-19 in L.C. 
Hulbert, ed. Third Midwest prairie conference proceed- 
ings. Kansas State University. Manhattan. 

Kirby. P. 1992. Habitat management for invertebrates: a prac- 
tical handbook. Royal Society for the Protection of Birds. 
Bedfordshire. U.K. 149 pp. 

New, T.R. 1993. Conservation biology of Lycaenidae (butter- 
flies). IUCN, Gland. Switzerland. 173 pp. 

Risser, P.G., E.C. Bimey. H.D. Blocker. S.W. May. W.J. 
Parton. and J. A. Wiens. 1981. The true prairie ecosystem. 
Hutchinson Ross Publishing Co., Stroudsburg, PA. 557 pp. 

Sauer, C. 1950. Grassland climax, fire and management. 
Journal of Range Management 3:16-20. 

Vogl, R.J. 1974. Effect of fire on grasslands. Pages 139-194 in 
T.T. Kozlowski and C.E. Ahlgren, eds. Fire and ecosys- 
tems. Academic Press. New York. 



Caves and springs tend to be inhabited by 
a highly specialized and intolerant 
diversity of vertebrate and invertebrate 
species. Ongoing research on the aquatic 
and terrestrial macroinvertebrates and terres- 
trial vertebrates inhabiting 105 springs and 
caves in Illinois (Figure) surveyed from 
1 990 to 1 993 has verified the uniqueness of 
this biota and highlighted the very fragile 
ecosystem in which these organisms survive. 
Data on more than 8,000 invertebrate speci- 
mens, representing 4 phyla, 1 1 classes, and 
32 orders, have been collected and the data 
entered into a data base. More than 2,500 
specimens and 27 species of vertebrates (3 
fishes, 7 salamanders, 4 frogs, 1 turtle, 4 




Figure. Distribution of springs and caves in 
Illinois. 



The Biota of Illinois 
Caves and Springs 

by 

Donald W. Webb 

Illinois Natural History Survey 



birds, 1 raccoon, and 7 bats) were observed 
in caves, dominated by the salamanders and 
bats. 

The water chemistry of the Illinois 
springs and cave streams was typical of most 
hardwater springs, although nitrate levels in 
one spring and one cave stream in the karst 
region of Monroe County exceeded the 
Illinois Pollution Control Board"s Maximum 
Contamination Level of 10 mg/L (10 ppm), 
raising concern over the effects of agricul- 
tural runoff on the biota of Illinois cave 
streams. The detection of mercury in the tis- 
sue of amphipods and isopods was noted, 
although no detectable level of mercury was 
determined in any of the water samples test- 
ed. 

Karst limestone regions have sinks, 
underground streams, and caves. Qualitative 
collections of invertebrates and observations 
of vertebrates were made to determine 
species richness and the spatial distribution 
of each species. In caves, habitat selection 
and cave preference (entrance, twilight, and 
dark zones) were examined for aquatic 
invertebrates and terrestrial vertebrates and 
invertebrates. 

The aquatic macroinvertebrates were 
dominated in abundance and diversity by 
noninsect arthropods, several of which are 
currently on federal and state endangered 
species lists (e.g., the amphipod Gammunts 



acherondytes). In terms of abundance, the 
amphipods Gammarus minus and G. 
pseudolimneaus and the turbellarian 
Phagocata gracilis dominated surface 
springs, while the amphipod G. troglophilus 
dominated cave streams. The diversity of 
oligochaete worms, with 24 taxa, proved to 
be the most surprising feature of the study, 
especially because several unidentified taxa 
of worms were collected that may be new 
species. Varichaetadrilus angustipenis, 
although previously collected only rarely in 
Illinois, was recorded from numerous 
springs. The collection of Allonais 
paraguayensis in Old Driver Spring was the 
most interesting find; this species has been 
reported only from a locality in Louisiana 
and an aquarium in New York. The presence 
of A. paraguayensis in Illinois represents a 
significant range extension for this species. 
The occurrence of unidentifiable taxa of 
Lumbricidae and Lumbriculidae also poses 
interesting systematic questions. 

Aquatic macrophytes were scarce in 
most springs examined, although the moss 
Leptodictyum riparium was abundant in the 
spring head of Old Driver Spring and the 
forb Mentha piperita plugged the upper 
reaches of the outflow channel of Old Driver 
and Rose springs. 

The terrestrial fauna of the cave was 
dominated by insects (heleomyzid and 
mycetophilid flies, collembolans. carabid 
and staphylinid beetles, and camel crickets), 
amphibians (seven species), and bats (seven 
species). The federally listed endangered 
gray bat (Myotis grisescens) was observed in 
one cave, and the Indiana bat (A/, sodalis) in 
six caves. The state-listed endangered south- 
eastern bat (M. austroriparius) was observed 
in two caves. The federally listed endan- 
gered Pleistocene disc snail (Discus 



Our Living Resources — Invertebrates 



177 



macdintocki) is known from one cave in 
northwestern Illinois. 

Implications of Surveys 

In Illinois, the biota of springs and cave 
streams typifies the hypothesis that hardwa- 
ter springs in eastern North America are 
dominated by noninsect macroinvertebrates 
(Glazier 1991). Although amphipods and 
turbellarians were the most abundant organ- 
isms in surface springs, it was the diversity 
evident within the oligochaete worms that 
proved the most exciting feature of surface 
springs. Twenty-four taxa, four of which 
may prove new to science, and several new 
state records were found. Several new local- 
ities for the spring cavefish Forbesichthys 
agassiz were also discovered. In the cave 
streams, the amphipods were the most 
diverse and abundant macroinvertebrates, in 
particular the troglobitic amphipod 
Gammarus troglophilus. Six state-endan- 
gered macroinvertebrates are known from 
Illinois caves. 

References 

Glazier, D.S. 1991. The fauna of North American 
temperate cold springs: patterns and hypothe- 
ses. Freshwater Biology 26:527-542. 

For Further Reading on Cave and Spring 
Biota 

Colbo, M.H. 1991. A comparison of the 
spring-inhabiting genera of Chironomidae from 
the Holarctic with those from natural and man- 
made springs in Labrador, Canada. Memoirs of 
the Entomological Society of Canada 155:169- 
179. 



Erman, N.A.. and D.C. Erman. 1990. 
Biogeography of caddisfly (Trichoptera) 
assemblages in cold springs of the Sierra 
Nevada (California, USA). Contribution 200, 
California Water Resources Center, University 
of California, Riverside. 28 pp. 

Forbes, S.A. 1882. The blind cave fishes and their 
allies. American Naturalist 16(1): 1-5. 

Forester, R.M. 1991. Ostracode assemblages from 
springs in the western United States: implica- 
tions for paleohydrology. Memoirs of the 
Entomological Society of Canada 155:181- 
201. 

Gardner, J.E. 1991. Illinois caves: a unique 
resource. Pages 447-452 in L.M. Page and 
M.R. Jeffords, eds. Our living heritage: the 
biological resources of Illinois. Bull, of the 
Illinois Natural History Survey 34(4):357-475. 

Glazier, D.S., and J.L. Gooch. 1987. 
Macroinvertebrate assemblages in 

Pennsylvania (U.S.A.) springs. Hydrobiologia 
150:33-43. 

Gooch, J.L., and D.S. Glazier. 1991. Temporal and 
spatial patterns in mid-Appalachian springs. 
Memoirs of the Entomological Society of 
Canada 155:29-49. 

Peck, S.B., and K. Christiansen. 1990. Evolution 
and zoogeography of the invertebrate cave fau- 
nas of the driftless area of the upper Mississippi 
River valley of Iowa, Minnesota, Wisconsin, 
and Illinois, USA. Canadian Journal of 
Zoology 68(l):73-88. 

Peck, S.B., and J.J. Lewis. 1977. Zoogeography 
and evolution of the subterranean invertebrate 
faunas of Illinois and southeastern Missouri. 
Bull, of the National Speleological Society 
40(2):39-63. 

Pritchard, G. 1991. Insects in thermal springs. 
Memoirs of the Entomological Society of 
Canada 155:89-106. 

Roughley, R.E., and D.J. Larson. 1991. Aquatic 
Coleoptera of springs in Canada. Memoirs of 
the Entomological Society of Canada 155:125- 
140. 



Smith, l.M. 1991. Water mites (Acari: 
Parasitengona: Hydrachnida) of spring habitats 
in Canada. Memoirs of the Entomological 
Society of Canada 155:141-167. 

Webb, D.W. 1993. Status survey for a cave amphi- 
pod. Gammarus acherondytes, Hubricht and 
Mackin (Crustacea: Amphipoda) in southern 
Illinois. Illinois Natural History Survey, Center 
for Biodiversity Tech. Rep. 1993(9):l-8. 

Webb, D.W., PC. Reed, and M.J. Wetzel. 1992. 
The springs of Illinois: a report on the fauna, 
flora, and hydrogeology of six basic-water 
springs in southern Illinois. Report to the 
Illinois Nature Preserves Commission. 
Unpublished. 41 pp. 

Webb, D.W., S.J. Taylor, and J.K. Krejca. 1993. 
The biological resources of Illinois caves and 
other subterranean environments. 

Determination of the diversity, distribution, and 
status of the subterranean faunas of Illinois 
caves and how these faunas are related to 
groundwater quality. Illinois Natural History 
Survey, Center for Biodiversity Tech. Rep. 
1993 (8):M57. 

Weise, J.G. 1957. The spring cave-fish. 
Chologaster papilliferus, in Illinois. Ecology 
38:195-204. 

Williams, D.D. 1991. Life history traits of aquatic 
arthropods in springs. Memoirs of the 
Entomological Society of Canada 155:63-87. 

Williams, N.E. 1991. Geographical and environ- 
mental patterns in caddisfly (Trichoptera) 
assemblages from coldwater springs in Canada. 
Memoirs of the Entomological Society of 
Canada 155:107-124. 

For further information: 

Donald W. Webb 

Illinois Natural History Survey 

Center for Biodiversity 

607 East Peabody Dr. 

Champaign, IL 61820 



The United States has the greatest diversity of 
freshwater mussels in the world. Of the five 
families and roughly 1,000 species occurring 
globally, nearly 300 species and subspecies in 
the families Unionidae and Margaritiferidae 
reside here (Turgeon et al. 1988). The number 
of mussels historically known for each state 
varies tremendously (Fig. 1 ), but the diversity of 
freshwater mussels in just the Southeast is 
unmatched by any other area in the world. 

Mussels were an important natural resource 
for Native Americans, who used them for food, 
tools, and jewelry. During the late 1800's and 
early 1900's, mussel shells supported an impor- 
tant commercial fishery; shells were used to 
manufacture pearl buttons until the advent of 
plastic buttons in the 1940's. Today the com- 
mercial harvest of freshwater mussel shells is 
exported to Asia for the production of spherical 
beads that are inserted into oysters, freshwater 
mussels, and other shellfish to produce pearls. 



There are no federal regulations on the har- 
vest of mussels, except those species on the fed- 
eral list of endangered or threatened species. 
Several states, however, regulate size, species, 
gear used, and season that mussels can be taken. 
Japanese demand for the high-quality U.S. mus- 
sel shells in recent years pushed the price to 
$13/kg ($6/lb) in 1991. Shell exports peaked in 
1991 at more than 8 million kg (9,000 tons), but 
demand declined in 1992 and 1993 and has lev- 
eled off to about 4 million kg (4,500 tons; Baker 
1993). 

Determining Status 

In reviewing the conservation status of fresh- 
water mussels, we included all species and sub- 
species recognized in the American Fisheries 
Society list of common and scientific names of 
mollusks from the United States and Canada 



Freshwater 
Mussels: A 
Neglected and 
Declining 
Aquatic 
Resource 

by 

James D. Williams 

Richard J. Neves 

National Biological Service 



178 



Invertebrates — Our Living Resources 



number 



Fig. 1. Number of species and 
subspecies of freshwater mussels 
historically known to occur within 
each state and the percentage now 
classified as imperiled. 





Freshwater mussels from the 
Tombigbee River at Memphis 
Landing. Pickens County, 
Alabama. Southern combshell 
(Epioblasma penita); female, top. 
male, bottom. 



(Turgeon et al. 1988). Distribution data and con- 
servation status were obtained from research pub- 
lications, books, original data from biologists, 
and a recent synopsis by Williams et al. (1993). 

The status categories were based on infor- 
mation for each species throughout its geo- 
graphic range. The conservation status cate- 
gories for a mussel species were defined as fol- 
lows: endangered — in danger of extinction 
throughout all or a significant portion of its 
range; threatened — is likely to become endan- 
gered throughout all or a significant portion of 
its range; special concern — may become threat- 
ened or endangered by relatively minor distur- 
bances to its habitat; undetermined — historical 
and current distribution and abundance have not 
been evaluated recently; and currently stable — 
distribution and abundance are seemingly sta- 
ble, or may have declined in portions of range 
but not in need of immediate conservation. 

Decline of Mussels 

The decline of freshwater mussels, which 
began in the late 1800's, has resulted from var- 
ious habitat disturbances, most significantly, 
modification and destruction of aquatic habitats 
by dams and pollution. Freshwater habitats suf- 



fer not only from direct alterations by humans 
but indirectly from abuse of terrestrial habitats, 
such as from siltation, especially evident if one 
compares the levels of imperilment of aquatic 
versus terrestrial species. Master (1990) recog- 
nized 55% of North America's mussels as 
extinct or imperiled, compared to only 7% of 
the continent's bird and mammal species. 

Aquatic habitat loss comes in a variety of 
forms such as from effects of dams, dredging, 
and channelization, or from more subtle effects 
of siltation and contaminants associated with 
construction and agriculture. Dams, with their 
altered flow regimes and attendant reservoirs, 
have caused the extirpation of 30%-60% of the 
native mussel species in selected U.S. rivers 
(Williams et al. 1992; Layzer et al. 1993). 
Siltation resulting from deforestation, poor agri- 
cultural and land-use practices, and removal of 
riparian vegetation can destabilize the stream bot- 
tom and eliminate benthic organisms such as 
mollusks (Ellis 1931). Many streams that look 
healthy can be polluted by contaminants like 
heavy metals, pesticides, and acid mine drainage. 
The effects of pollution and habitat alteration on 
mussels were reviewed by Fuller (1974). 

Competition from non-native mollusks also 
has contributed to the loss of native mussel pop- 
ulations. The Asian clam (Corbicula fluminea), 
introduced to the U.S. west coast in the 1930's, 
has invaded nearly every watershed nationwide 
(McMahon 1983). Local population explosions 
of the Asian clam have adversely affected some, 
but not all, native mussels (Belanger et al. 1990; 
Leff et al. 1990). The recently introduced zebra 
mussel {Dreissena polymorpha) appears poised 
to decimate many of the remaining mussel pop- 
ulations. Zebra mussels were discovered in the 
United States at Lake St. Clair in 1988 and 
spread rapidly throughout the Great Lakes. In 
1991 they were found in the Illinois River, and 
by late 1 99 1 had spread to the Tennessee River 
(Nalepa and Schloesser 1992). They are now 
found throughout the Mississippi River and por- 
tions of its major tributaries, even to southern 
Louisiana. During the next 10-20 years, zebra 
mussels will most likely spread throughout 
most of the United States and southern Canada. 

The adverse modification and destruction of 
aquatic habitats, along with the introduction of 
nonindigenous species, have resulted in the 
decline of freshwater mussels. The percentage 
of imperiled mussel species for eastern states is 
high (Fig. 1 ). Of the 297 native mussel species 
in the United States, 71.7% are considered 
endangered, threatened, or of special concern 
(Fig. 2), including 21 mussels that are endan- 
gered and presumed extinct. Seventy species 
(23.6%) are considered to have stable popula- 
tions (Fig. 2), although many of these also have 
declined in abundance and distribution. Many 



Our Living Resource 



Invertebrates 



179 



species in the latter group occur in larger rivers 
and reservoirs and are projected to suffer severe 
declines as the zebra mussel invades these 
ecosystems. 

The rapid decline of mussels during this cen- 
tury went almost unnoticed until the past 30 
years. Although most of the described threats to 
survival of mussels have existed for more than a 
century, the increased geographic area covered 
by these threats and the cumulative effects of 
human expansion and development have now 
overwhelmed aquatic systems. 

The demise in both populations and species 
diversity of our mussel fauna is likely occurring 
in other freshwater mollusks (especially snails) 
and aquatic organisms, but too few surveys have 
been conducted to record such trends. 
Conservation and restoration should focus on 
the ecosystem and watershed level instead of 
directing concerns to the individual species. To 
effectively carry out such a broad recovery 
effort will require an unparalleled level of coop- 
eration and coordination of private, state, and 
federal agencies. Perhaps even more critical to 
the success of ecosystem and watershed conser- 
vation is the involvement of the general public, 
conservation organizations, and private corpo- 
rations. If the decline of aquatic mollusks con- 
tinues, we will witness the greatest extinction of 
these organisms experienced in modern times. 

References 

Baker, P.M. 1993. Resource management: a shell exporter's 
perspective. Pages 69-71 in K.S. Cummings, A.C. 
Buchanan, and L.M. Koch, eds. Conservation and 
Management of Freshwater Mussels. Proceedings of a 
symposium. Illinois Natural History Survey, Champaign. 



Belanger, T.V., C.G. Annis, and D.D. VanEpps. 1990. Growth 
rates of the Asiatic clam, Corbkula fluminea, in the upper 
and middle St. Johns River. Florida. Nautilus 104:4-9. 

Ellis. M.M. 1931. Some factors affecting the replacement of 
the commercial fresh-water mussels. U.S. Bureau of 
Fisheries Fishery Circular 7:1-10. 

Fuller, S.L.H. 1974. Clams and mussels (Mollusca: 
Bivalvia). Pages 215-273 in C.W. Hart and S.L.H. Fuller, 
eds. Pollution ecology of freshwater invertebrates. 
Academic Press. New York. 

Layzer, J.B., M.E. Gordon, and R.M. Anderson. 1993. 
Mussels: the forgotten fauna of regulated rivers. A case 
study of the Caney Fork River. Regulated Rivers: 
Research and Management 8:63-71. 

Leff, L.G., J.L. Burch, and J.V. McArthur. 1990. Spatial dis- 
tribution, seston removal, and potential competitive inter- 
actions of the bivalves Corbkula fluminea and Elliptio 
complanata. in a coastal plain stream. Freshwater Biology 
24:409-416. 

Master, L. 1990. The imperiled status of North American 
aquatic animals. Biodiversity Network News 3:1-2, 7-8. 

McMahon, R.F. 1983. Ecology of an invasive pest bivalve, 
Corbicula. Pages 505-561 in W.D. Russell-Hunter, ed. 
The Mollusca. Vol. 6. Ecology. Academic Press, New 
York. 

Nalepa, T.F., and D.W. Schloesser, eds. 1992. Zebra mussels: 
biology, impacts, and control. Lewis Publishers. Boca 
Raton, FL. 

Turgeon, D.D., A.E. Bogan, E.V. Coan, W.K. Emerson, W.G. 
Lyons, W.L. Pratt, C.F.E. Roper, A. Scheltema, EG. 
Thompson, and J.D. Williams. 1988. Common and scien- 
tific names of aquatic invertebrates from the United States 
and Canada: Mollusks. American Fisheries Society 
Special Publ. 16. 277 pp. 

Williams, J.D., S.L.H. Fuller, and R. Grace. 1992. Effects of 
impoundment on freshwater mussels (Mollusca: Bivalvia: 
Unionidae) in the main channel of the Black Warrior and 
Tombigbee rivers in western Alabama. Bull. Alabama 
Museum of Natural History 13:1-10. 

Williams J.D., M.L. Warren. Jr., K.S. Cummings, J.L. Harris, 
and R.J. Neves. 1993. Conservation status of freshwater 
mussels of the United States and Canada. Fisheries 
18(9):6-22. 




7.1% 


4.7% 


Endangered and 


Undetermined 


presumed extinct 


14 mussel 


21 mussel taxa 


taxa 



Fig. 2. The percentage of the U.S. 
mussel fauna classified by conser- 
vation status category: undeter- 
mined, endangered and presumed 
extinct, endangered, threatened, 
special concern, and stable. 



For further information: 

James D. Williams 

National Biological Service 

Southeastern Biological Science 

Center 

7920 N.W. 71st St. 

Gainesville, FL 32653 



An early indicator of adverse human effects 
on large open-water systems in North 
America was western Lake Erie, part of the 
Lake Huron-Lake Erie corridor of the 
Laurentian Great Lakes (Fig. 1 ). Local pollution 
of tributaries of western Lake Erie was recog- 
nized as early as 1890, when populations of 
whitefish (Salmonidae) and lake herring 
{Coregonus artedi) in the Detroit River declined 
(Beeton 1961). Waters of western Lake Erie 
stopped yielding whitefish and herring in the 
1920's-30's, but not until the 1950's, after 
extensive biological investigations, were the 
open waters of western Lake Erie believed to 
have been polluted by human "local" activities 
(National Academy of Sciences 1970). 
Eutrophication (the addition of nutrients) of 
western Lake Erie created unsuitable conditions 
(primarily low dissolved oxygen concentra- 
tions) for fish and other animals in a major por- 
tion of Lake Erie — the world's 12th largest lake. 
By the early 1960's, Lake Erie was declared 
"biologically dead" (Burns 1985). 



Among the many ecosystem components 
affected by human-induced changes to western 
Lake Erie (Burns 1985) is the native mussel 
fauna (Bivalvia: Unionidae). Reduced mussel 
populations that survived degraded conditions of 
the 1950's have been used in status and trends 
studies to evaluate traditional forms of pollution 
in western Lake Erie. Studies in the 1990's have 
focused on evaluating the effects of exotic 
species on mussel populations in the Lake 
Huron-Lake Erie corridor. Exotic species have 
recently been characterized as "biological pollu- 
tion," a new concept in evaluating status and 
trends data. Our study shows both historical, 
long-term effects from human activities and 
recent, dramatic effects from exotic species on 
mussel populations in waters of the Great Lakes. 

Sampling Populations 

The Lake Huron-Lake Erie corridor receives 
water from three of the five Laurentian Great 
Lakes, the largest freshwater system in the world 



Freshwater 
Mussels in the 
Lake Huron- 
Lake Erie 
Corridor 

by 

Don W. Schloesser 

National Biological Service 

Thomas F. Nalepa 

National Oceanic and 

Atmospheric Administration 



180 



Invertebrates — Our Living Resources 



Fig. 1. The Lake Huron-Lake Erie 
corridor, including Lake St. Clair 
and western Lake Erie (in red). 



(Fig. 1). Relatively pristine water enters the St. 
Clair River, passes through Lake St. Clair and 
the Detroit River, and enters western Lake Erie. 
Freshwater native mussels were collected by 
scuba divers in the Lake Huron-Lake Erie corri- 
dor (Fig. 1) at 46 stations during six sampling 
periods from 1961 to 1992. In Lake St. Clair, 
mussels were collected at 29 stations in 1986, 
1990, and 1992. Ten replicate quadrate samples 
(0.5 m 2 each [5.4 ft 2 ]) were obtained at each 
station and sampling date. In western Lake Erie, 
mussels were collected four times at one index 
station in 1989-91 and once at 17 historically 
sampled stations in 1961, 1982, and 1991. 
Sampling at the index station was performed 
with an epibenthic sled (46 x 25 cm [18 x 63 
in]). Sampling at the 17 historically sampled 
stations was performed with a Ponar grab sam- 
pler. Three replicate Ponar (0.05 m 2 [0.5 ft 2 ]) 
samples of the substrate were collected at each 
station. Mussels were identified following 
Clarke (1981) and comparisons with bivalve 
taxonomic reference collections. Taxonomic 
nomenclature follows Turgeon et al. (1988) and 
Williams etal. (1993). 




Historical Status 

Around 1 900 the Lake Huron-Lake Erie cor- 
ridor was characterized as having one of the 
most abundant freshwater mussel faunas in 
North American lakes (Goodrich and van der 
Schalie 1932; Mackie et al. 1980): 39 species 
(Table 1). 

Before 1990 mussel populations existed in 
most areas of the Lake Huron-Lake Erie corri- 
dor (Fig. 2). In Lake St. Clair, mussel popula- 
tions were similar in 1986 and 1990 (Table 2). 
Numbers of mussels per unit area were relative- 







Table 1. Species of native mussels historically found in 
the Lake Huron-Lake Erie corridor of the Great Lakes 
(modified from Clarke and Stansbery 1988). 

Species 

Mucket (Actinonaias ligamentina [carinata]) 

Elktoe (Alasmidonta marginata) 

Slippershell mussel (A viridis) 

Threeridge ( Amblema plicata plicata) 

Cylindrical papershell (Anodontoides lerussacianus) 

Purple wartyback (Cyclonaias tuberculata) 

Spike (Elliptio dilatata) 

Northern ritfleshell (Epioblasma toruiosa rangiana) 

Snuffbox (£ Inquetra) 

Wabash pigtoe (Fusconaia flava) 

Wavy-rayed lampmussel (Lampsilis fasciola) 

Pocketbook (L ovata) 

Eastern lampmussel (L siliquoidea) 

White heelsplitter (Lasmigona complanata complanata) 

Creek heelsplitter (A, compressa) 

Fluted-shell (L. costata) 

Fragile papershell (Leptodea Iragilis ) 

Eastern pondmussel (Ligumia nasuta) 

Black sandshell (L recta) 

Threehorn wartyback (Obliquaria reflexa) 

Hickorynut (Obovaria olivaria) 

Round hickorynut (0. subrotunda) 

Round pigtoe (Pleurobema coccineum) 

Ohio pigtoe (P. cordatum) 

Pink heelsplitter (Polamilus alatus) 

Pink papershell (P. ohiensis) 

Kidneyshell (Ptychobranchus lasciolaris) 

Giant floater (Pyganodon grandis) 

Mapleleaf (Quadrula quadrula) 

Pimpleback (0. pustulosa pustulosa) 

Salamander mussel (Simpsonaias ambigua) 

Squawfoot (Strophilus undulatus) 

Lilliput ( Toxolasma parvus) 

Fawnsfoot ( Truncilla donaciformis) 

Deertoe (T. truncata) 

Pondhorn (Uniomerus tetralasmus) 

Paper pondshell (Utlerbackia imbecillis) 

Rayed bean ( Villosa labalis) 

Rainbow ( V. iris) 

Table 2. Number of species of native mussels and aver- 
age (mean) density (number/m 2 ) in Lake St. Clair and 
western Lake Erie of the Lake Huron-Lake Erie corridor. 
1961-92. 





Lake/year 



Total no. of species 



Average (mean) 
no/m 2 



Lake St. Clair 



1986 


18 


2 


1990 


16 


2 


1992 


12 


<1 


Western Lake Erie 


1961 


8 




1982 


5 


4 


1991 









ly low (2/m 2 [0.2/ft 2 ]), but consistent, and there 
were 16-18 species found throughout the lake in 
1990. The relatively healthy populations of 
mussels are attributed to the pristine water flow- 
ing into the lake from Lake Huron (Herdendorf 
etal. 1986). 

In western Lake Erie, mussel populations 
that had survived low water quality in the 
1950's declined between 1961 and 1982 (Table 
2). Numbers declined from 10/m 2 (0.9/ft 2 ) to 
4/m 2 (0.4/ft 2 ), and the number of species 



Our Living Resources — Invertebrates 



181 






1 

<1 vs 
2 1 2 

CO 




2 




2 <1 




2 1 1 <1 
2 11 <1 




7 2 2 10 1 




14 2 2 <1 




3 , , 

1990 




Lake St. Clair 





<1 
4 <1 
1 


O 

55 




1 1 
<1 1 <1 
3 <1 


<1 




6 10 

















1992 

Lake St. Clair 





4 

8 


4 

8 
4 


/ 8 14 D 18 
8 4 
,„ 22 


4 
8 


13 




1961 




Western Lake Erie 





^ 


















<£ 






'§ 






Qi 






Q 


21 












14 







°7 





f 









7 






n 


14 










7 
1982 






Western Lake Erie 



a? 

















° 





° 


1991 






Western Lake Erie 



declined from eight to five between 1961 and 
1982. The declining populations of native mus- 
sels are attributed to pollution that originated 
from tributary rivers of the lake prior to the 
1970's. In the mid-^VO's, pollution-abatement 
programs were begun, and water and substrate 
quality began to improve in western Lake Erie 
by the mid-1980's. By the late 1980's, environ- 
mental quality improved dramatically and pol- 
lution-sensitive indicators such as burrowing 
mayflies (Hexagenia spp.) began to return to 
western Lake Erie (Farara and Burt 1993; 
Schloesser, unpublished data). 

Current Status 

In the early 1990's, however, native mussel 
populations declined dramatically in the Lake 
Huron-Lake Erie corridor, despite improve- 
ments in water and substrate quality (Fig. 2; 
Table 2). In Lake St. Clair, substantial declines 
of mussels were documented between 1990 and 
1992. Numbers and species of mussels were 
about half those found only 2 years earlier. 
Most changes in mussel populations in Lake St. 
Clair occurred in the southern portion of the 
lake, where mussels are no longer found (Fig. 
2). In Lake Erie, mussel populations virtually 
disappeared in offshore waters between 1982 
and 1991 (Fig. 2; Table 2). 

Recent changes in native mussel populations 
in the Lake Huron-Lake Erie corridor are attrib- 



uted to mortality caused by the exotic zebra 
mussel (Dreissena polymorpha); these exotics 
attach to the surface of mussels in such high 
numbers that native mussels are unlikely to be 
able to breathe and eat (Fig. 3). Intensive sam- 
pling indicated that native mussel populations 
declined rapidly between September 1989 and 
May-June 1990 (Fig. 4). Zebra mussels became 
abundant the summer of 1989, when infestation 
on clams increased from 24 mussels to 7,000 
mussels per clam (Schloesser and Kovalak 
1991; Nalepa and Schloesser 1992). 

Erosion caused by deforestation, poor agri- 
cultural practices, and destruction of riparian 
zones, and organic and inorganic pollution have 
long been recognized as other causes for mussel 
mortality (Williams et al. 1993). Our knowledge 
of the zebra mussel, however, and its coloniza- 
tion on native mussels indicates that native mus- 
sel mortalities in the 1990's are attributable to 




Fig. 2. Average (mean) densities 
(number/m 2 ) of native mussels in 
Lake St. Clair and western Lake 
Erie of the Lake Huron-Lake Erie 
corridor of the Great Lakes, 1961- 
92. 



Fig. 3. Typical native mussel (Potamilus alatus) uncolo- 
nized (left) and colonized (right) by the exotic zebra mus- 
sel (Dreissena polymorpha) in the Lake Huron-Lake Erie 
corridor of the Great Lakes. 



182 



Invertebrates — Our Living Resources 




Fig. 4. Percentage of live and 
dead native mussels collected at an 
index station in western Lake Erie 
of the Lake Huron-Lake Erie cor- 
ridor of the Great Lakes, 1989-91. 



For further information: 

Don W. Schloesser 

National Biological Service 

Great Lakes Science Center 

Ann Arbor, MI 48105 



biological pollution. Exotic species such as 
zebra mussels are being recognized as new and 
widespread threats to ecosystem stability 
throughout North America (Office of 
Technology Assessment 1993). 

References 

Beeton, A.M. 1961. Environmental changes in Lake Erie. 
Transactions of the American Fisheries Society 90:153- 
159. 

Burns, N.M. 1985. Erie: the lake that survived. Rowman and 
Allanheld, Totowa, NJ. 320 pp. 

Clarke, A.H. 1981. The freshwater molluscs of Canada. 
National Museum of Natural Sciences, Ottawa. 446 pp. 

Clarke, A.H., and D.H. Stansbery. 1988. Are some Lake Erie 
mollusks products of post-Pleistocene evolution? Pages 
85-92 in J.F. Downhower, ed. The biogeography of the 
island region of western Lake Erie. Ohio State University 
Press, Columbus. 208 pp. 

Farara, D.G, and A.J. Burt. 1993. Environmental assessment 
of western Lake Erie sediments and benthic communi- 
ties — 1991. Ontario Ministry of Environment and Energy, 
Water Resources Branch, Great Lakes Section by Beak 
Consultants Limited. Brampton, Ontario. 193 pp. 

Goodrich, C, and H. van der Schalie. 1932. The naiad 
species of the Great Lakes. Occasional Papers of the 
Museum of Zoology University of Michigan 238:8-14. 

Herdendorf, C.E., C.N. Raphael, and E. Jaworski. 1986. The 
ecology of Lake St. Clair wetlands: a community profile. 



U.S. Fish and Wildlife Service Biological Rep. 85(7.7). 
187 pp. 

Mackie, G.L., D.S. White, and T.W. Zdeba. 1980. A guide to 
freshwater mollusks of the Laurentian Great Lakes with 
special emphasis of the genus Pisidium. U.S. 
Environmental Protection Agency EPA-600/3-80-068. 
Duluth, MN. 144 pp. 

Nalepa. T.F.. and D.W. Schloesser, eds. 1992. Zebra mussels: 
biology, impacts, and control. CRC Press, Inc.. Boca 
Raton, FL. 810 pp. 

National Academy of Sciences. 1970. Eutrophication: caus- 
es, consequences, correctives. Proceedings of a sympo- 
sium. Washington. DC. 661 pp. 

Office of Technology Assessment (U.S. Congress). 1993. 
Harmful non-indigenous species in the United States. 
OTA-F-565. U.S. Government Printing Office, 
Washington, DC. 390 pp. 

Schloesser. D.W.. and W.P. Kovalak. 1991. Infestation of 
unionids by Dreissena polymorpha in a power plant canal 
in Lake Erie. Journal of Shellfish Res. 10(2): 355-359. 

Turgeon, D.D., A.E. Bogan. E.V. Coan. W.K. Emerson, W.G. 
Lyons, W.L. Pratt, C.F.E Roper. A. Scheltema. EG 
Thompson, and J.D. Williams. 1988. Common and scien- 
tific names of aquatic invertebrates from the United States 
and Canada: mollusks. American Fisheries Society 
Special Publ. 16. 277 pp. 

Williams, J.D.. M.L. Warren. Jr.. K.S. Cummings. J.L. 
Harris, and R.J. Neves. 1993. Conservation status of 
freshwater mussels of the United States and Canada. 
Fisheries 18(9):6-22. 



Aquatic 
Insects As 
Indicators of 
Environmental 
Quality 

by 

William T. Mason, Jr. 

National Biological Service 

Calvin R. Fremling 

Winona State University 

Alan V. Nebeker 

U.S. Environmental 

Protection Agency 



Aquatic insects are among the most prolific 
animals on earth, but are highly specialized 
and represent less than 1 % of the total animal 
diversity (Pennak 1978). Most people know the 
12 orders and about 11,000 species of North 
American aquatic insects (Merritt and 
Cummins 1984) only by the large adults that fly 
around or near wetlands. 

Aquatic insects are excellent overall indica- 
tors of both recent and long-term environmental 
conditions (Patrick and Palavage 1994). The 
immature stages of aquatic insects have short life 
cycles, often several generations a year, and 
remain in the general area of propagation. Thus, 
when environmental changes occur, the species 
must endure the disturbance, adapt quickly, or 
die and be replaced by more tolerant species. 
These changes often result in an overabundance 
of a few tolerant species, and the communities 
become destabilized or "unbalanced." 

Members of the order Diptera, or true flies, 
are especially good "bioindicators" of aquatic 
environmental conditions because, in addition 
to the attributes of other aquatic insects, they 
occupy the full spectrum of habitats and condi- 
tions (Paine and Gaufin 1956; Roback 1957: 
Mason 1975; Hudson et al. 1990). 

Although considerable information on 
aquatic insects and other macroinvertebrates 
has been collected since the 1950's. most stud- 
ies have been abbreviated surveys. There are 
few good examples of long-term biomonitoring 
of aquatic insects in the United States because 



of the discontinuance of most routine biomoni- 
toring in the 1980's. We present ongoing and 
past examples of surveillance monitoring of 
aquatic insects of the Ohio and Mississippi 
rivers. Our interest here centers on the immature 
stages of aquatic insects that, although usually 
unnoticed, are part of the framework of natural 
ecosystems (Fig. 1 ). 

Ohio River Aquatic Insects 

During 1963-67. aquatic insects (primarily 
midges [Diptera], caddisflies [Trichoptera], 
mayflies [Ephemeroptera], and stoneflies 
[Plecoptera]) and other benthic invertebrates 
were monitored at 80-161 km (50-100 mi) 
increments along the 1,582 km (963 mi) of the 
mainstem Ohio River from Pittsburgh. 
Pennsylvania, to Cairo, Illinois (Mason et al. 
1971 ). Rock-filled basket samplers were a pre- 
liminary collection device in addition to Ponar 
substrate grab collections. 

In the upper Ohio River from river mile to 
260 (418 km) at Addison, Ohio, during 1965- 
67, the aquatic insect diversity (Fig. la) and 
individuals (Fig. lb) in rock-filled basket sam- 
plers were low compared with collections from 
downriver sites. The macroinvertebrate fauna 
consisted mostly of pollution-tolerant midge 
larvae and worms, indicating poor to fair water 
quality. In the lower reach from Louisville to 
Evansville (distance of about 200 river miles or 
322 km) the fauna was double to triple that of 



Our Living Resources — Invertebrates 



183 



the upriver stations and contained facultative 
and some clean-water taxa, indicating improved 
water quality. 

Although the total aquatic insect diversity in 
the baskets at river mile 601 (968 km) in 1965 
exceeded those at river mile 788 (1,268 km) by 
about one-third, during the next 2 years the 
diversity at Evansville increased over that at 
Louisville by 30%-40%. This significant 
increase was probably caused by environmental 
changes (e.g., increased eutrophication that pro- 
vided more foods for these insects) that favored 
Chironomidae nonbiting midges and 
Hydropsychidae net-spinning caddisflies. 
During the 3-year period, pollution-tolerant 
species replaced some of the clean-water 
"green" species. 

Aquatic insects are also useful indicators of 
contamination of the sediments and waters that 
may have gone unnoticed by routine physico- 
chemical measurements. Uptake of toxic sub- 
stances, such as heavy metals and organochlo- 
rine compounds, causes various kinds of defor- 
mities of the larval and pupal Chironomidae 
(Hamilton and Saether 1971; Lenat 1993). 
Depending on the severity of the pollution, these 
deformed individuals do not reach maturity and 
the populations are eventually reduced (van Urk 
et al. 1992). During the 1963-67 Ohio River 
monitoring program, Mason and Lewis 
observed larval deformities in samples taken 
from the sediments from the upper reaches of 
the Ohio River near Pittsburgh, Pennsylvania, 
the lower Monongahela River, and Kanawha 
River (Mason, unpublished data). 

Management Implications 

There is a need to establish long-term moni- 
toring and reporting on macroinvertebrate popu- 
lations such as that carried out during 1963-67. A 
monitoring program could evaluate the success 
of pollution clean-up and identify biological 
indicators to help balance water uses among 
urban centers, transportation, industry, and fish- 
ing and other recreation. Water chemistry and 
physical measurements alone are not sufficient 
to determine subtle shifts in aquatic populations. 

Locating point sources of contaminants or 
thermal wastes so that they discharge directly to 
trout streams and lakes usually results in loss of 
stonefly populations, which, in turn, adversely 
affects fisheries. The effects of aerial spraying 
and other types of insecticide applications on 
stonefly and other sensitive aquatic organisms 
should be considered during site-preparation 
planning. Natural resource managers often rec- 
ommend set backs, or buffer strips of unfilled 
land adjacent to streams, as an effective way to 
minimize harm from pollution runoff. 




*- co »- 



J- CsJ 



1 6,710 Mostly worms 
b. 

m 1965 






W 2,366 


o 

° 7 


CD 1966 




a> F 


■i 1967 




=9 t; 












1 


j 


-o 4 

> 








| 


1 J 
° 2- 

1 1 




No samples 



o *- 



CO i- 



*- C\J 



c ".= 



"O 1^3 



City 

Mississippi River Ephemeroptera 

The nymphs of burrowing mayflies 
(Ephemeroptera) live in U-shaped tubes in the 
silt bottoms of shallow, slow-moving waters 
(Berner and Pescador 1988). Although mass 
emergences of adult burrowing mayflies in the 
Upper Mississippi River have been considered a 
nuisance (Fremling 1968), their abundance rep- 
resents a wealth of fish food biomass; their 
abundance also reflects environmental health. 

During 1957-69, three species of burrowing 
mayflies (Hexagenia bilineata, H, litnbata, and 
Pentagenia vittigera) were monitored in the 
3,218-km (2,000-mi) reach of the Mississippi 
River from Minneapolis, Minnesota, to New 
Orleans, Louisiana (Fremling 1964, 1970). In 
the 1930's, 29 navigation dams were built in the 
upper reaches of the Mississippi River, and bur- 
rowing mayflies became abundant in the slow- 
moving silted shallows. The insects were much 
less abundant downstream from St. Louis, 
Missouri, where no dams existed. The surveys 
of Mississippi River mayflies continue today. 

During the years 1957-69 and 1976, about 
1,300 collections of Hexagenia showed that 
most of the navigation pools and impoundments 
upstream from Minneapolis and St. Paul, 
Minnesota, supported large populations of bur- 
rowing mayflies. Both Hexagenia species were 



Fig. 1. (a) Total number of aquat- 
ic insect and other macroinverte- 
brate taxa and (b) average number 
of individuals collected in basket 
samplers in the Ohio River. 1965- 
67 (Mason et al. 1971). 



184 



Invertebrates — Our Living Resources 



For further information: 

William T. Mason, Jr. 

National Biological Service 

Southeastern Biological Science 

Center 

7920 N.W. 71st St. 

Gainesville, FL 32653 



conspicuously rare in the 48-km (30-mi) reach 
downstream from the Twin Cities. There, a 
heavy pollutant load caused low dissolved oxy- 
gen levels on the river bottom for much of the 
year. The mayflies were also rare in the upper 
reach of Lake Pepin, a large (32-km [20-mi]) 
natural impoundment farther downstream, 
where they had been abundant in years past. 
Apparently Lake Pepin was a settling basin for 
pollutants and decaying algae caused by over- 
fertilization from the Twin Cities area. 

A 1986 mayfly survey revealed that recent 
pollution abatement measures in the Twin Cities 
created favorable conditions for mayflies to 
return to densities of the 1950's-60's. The dis- 
tribution of Hexagenia species reflects the sta- 
tus of aquatic life inhabiting a large river that 
was otherwise difficult to monitor effectively or 
economically by standard chemical testing 
(Fremling 1989, 1990). 

Management Implications 

As with the Ohio River insects, there is a 
need to maintain a network of routine monitor- 
ing stations along the 3,218 km (2,000 mi) of 
the Mississippi River to learn when atypical 
emergences of mayflies and other aquatic 
insects occur. This information will allow pub- 
lic officials and administrators to pinpoint more 
intensive and detailed analytical surveys that 
could determine causes of the emergences. 

Today, the greatest future threat to the bur- 
rowing mayflies in the Mississippi River lies in 
accelerated siltation and subsequent filling of the 
navigation pools. These filled areas are rapidly 
becoming floodplain forests, a conversion that 
eliminates them as burrowing mayfly habitat, 
thereby reducing food stocks for fisheries. 

References 

Berner, L., and M.L. Pescador. 1988. The mayflies of Florida. 
University of Florida Press, Gainesville. 415 pp. 

Fremling, C.R. 1964. Mayfly distribution indicates water qual- 
ity on the Upper Mississippi River. Science 
146(3648):1 164-1 166. 

Fremling, C.R. 1968. Documentation of mass emergence of 
Hexagenia mayflies from the Upper Mississippi River. 



Transactions of the American Fisheries Society 97(3):278- 
281. 

Fremling, C.R. 1970. Mayfly distribution as a water quality 
index. Water Pollution Control Research Series 16030 
DQH 1 1/70. U.S. Environmental Protection Agency. Water 
Quality Office. Washington, DC. 39 pp. 

Fremling, C.R. 1989. Hexagenia mayflies: biological monitors 
of water quality in the Upper Mississippi River. Journal of 
the Minnesota Academy of Science 55( 1 ): 139-143. 

Fremling, C.R. 1990. Recurrence of Hexagenia mayflies 
demonstrates improved water quality in Poo! 2 and Lake 
Pepin, Upper Mississippi River. Pages 243-248 in l.C. 
Campbell, ed. Mayflies and stoneflies. Kluwer Academic 
Publishers. The Netherlands. 

Hamilton. A.L., and O.A. Saether. 1971. The occurrence of 
characteristic deformities in the chironomid larvae of sever- 
al Canadian lakes. Canadian Entomologist 103:363-368. 

Hudson. P.L., D.R. Lenat, B.A. Caldwell, and D. Smith. 1990. 
Chironomidae of the southeastern United States: a checklist 
of species and notes on biology, distribution, and habitat. 
U.S. Fish and Wildlife Service Fish and Wildlife Res. 7. 
46 pp. 

Lenat. D.R. 1993. Using mentum deformities of Chironomus 
larvae to evaluate the effects of toxicity and organic loading 
in streams. Journal of the North American Benthological 
Society 12:265-269. 

Mason, W.T., Jr. 1975. Chironomidae (Diptera) as biological 
indicators of water quality. Pages 40-51 in C.C. King and 
L.E. Elfner, eds. Organisms and biological communities as 
indicators of environmental quality. Circular 8. Ohio 
Biological Survey. Columbus. 

Mason, W.T., Jr., P.A. Lewis, and J.B. Anderson. 1971. 
Macroinvertebrate collections and water quality monitoring 
in the Ohio River Basin 1963-1967. Office of Technical 
Programs, Ohio Basin Region, and Analytical Quality 
Control Laboratory, U.S. Environmental Protection 
Agency. Cincinnati, OH. 52 pp. 

Merritt, R.W., and K.W. Cummins. 1984. Introduction. Pages 
1-3 in R.W. Merritt and K.W. Cummins, eds. An introduc- 
tion to the aquatic insects of North America. 2nd ed. 
Kendall/Hunt Publishing Company. Dubuque. IA. 

Paine. G.W., and A.R. Gaufin. 1956. Aquatic Diptera as indi- 
cators of pollution in a midwestern stream. The Ohio 
Journal of Science 56:291-304. 

Patrick. R.. and D.M. Palavage. 1994. The value of species as 
indicators of water quality. Proceedings of the Academy of 
Natural Sciences Philadelphia 145:55-92. 

Pennak, R.W. 1978. Fresh-water invertebrates of the United 
States. 2nd ed. John Wiley & Sons, Inc. New York. 803 pp. 

Roback, S.S. 1957. The immature tendipedids of the 
Philadelphia area. Academy of Natural Sciences of 
Philadelphia Monograph 9. 152 pp. 

van Urk. G., F.C.M. Kerkum, and H. Smit. 1992. Life cycle 
patterns, density, and frequency of deformities in 
Chironomus larvae (Diptera: Chironomidae) over a conta- 
minated sediment gradient. Canadian Journal of Fisheries 
and Aquatic Sciences 49:2291-2299. 



Biodiversity 
Degradation 
in Illinois 
Stoneflies 

by 

Donald W. Webb 

Illinois Natural History 

Survey 



Preliminary analysis of the recent collections 
of Illinois stoneflies indicates a reduction in 
the species richness in Illinois, a reduction in 
the spatial distribution of many species, the 
dominance of more generalist species more tol- 
erant to environmental perturbations, and the 
extirpation of several species. 

These general trends can be expanded for all 
of the central United States. The reduction in 
stream flow through the construction of locks 
and dams and the resulting effect of increased 
sedimentation have severely affected the habitat 



and niche selection available to species such as 
stoneflies that require rapidly flowing streams. 
This situation has been compounded by the ero- 
sional effects of deforestation and agricultural 
practices, which are maximizing the amount of 
land put into cultivation, as well as the 
increased problems related to nonpoint pollu- 
tion from agricultural pesticides and fertilizers. 
To properly delineate these trends, the status of 
stoneflies and most other groups of aquatic 
organisms in the central United States needs to 
be evaluated. 



Our Living Resources — Invertebrates 



1X5 



In Illinois, stoneflies (Insecta: Plecoptera) 
were collected extensively from 1926 through 
1940 by T.H. Frison (Frison 1929, 1935, 1937, 
1942), with additional winter-emerging stone- 
flies collected from 1960 to 1970 by H.H. 
Ross's "Winter Stonefly Club" (Ricker and 
Ross 1968, 1969: Ross and Ricker 1971). From 
the thousands of specimens collected, the 
Illinois Natural History Survey has an excep- 
tional record of species diversity and spatial dis- 
tribution of Illinois stoneflies. 

In 1990 we began a reevaluation of the 
species richness and spatial distribution of 
Illinois stoneflies (Webb and Harris 1993). The 
focus of this study was to compare current 
species richness and distribution patterns with 
those determined by Frison, Ross, and Ricker. 
To do this, we developed a data base for the 
Illinois specimens in the collections of the 
Illinois Natural History Survey, and we exten- 
sively resurveyed stoneflies in each of the 25 
major drainages within the state (Figure). 

Status 

We evaluated the status of each stonefly 
species on the basis of the locality information 
and classified each species as rare, uncommon, 
or common (Table). This evaluation revealed 
that 39% of the 61 species reported were known 




Figure. Twenty-five major river drainages in Illinois. 



from three localities or fewer. In addition, we 
developed a checklist of the Illinois species and 
updated their varied nomenclature. 

After 4 years of collecting we consider 13 
Illinois stonefly species rare (Acroneuria filicis 
Frison; A. perplexa Frison; Allocapnia nivicola 
[Fitch]; A. smithi Ross and Ricker; Haploperla 
brevis [Banks]; lsoperla burksi Frison; 
Nemoura trispinosa Claassen; Paragnetina 
media [Walker]; Prostoia completa [Walker]; 
Shipsa rotunda [Claassen]; Soyedina vallicular- 
ia [Wu]; Zealeuctra fraxina Ricker and Ross; 
and Z. narfi Ricker and Ross). We found that 6 
have been extirpated from Illinois (Allocapnia 
illinoensis Frison; Alloperla roberti Surdick; 
Amphinemura nigritta [Provancher]; lsoperla 
conspicua Frison; /. marlynia [Needham and 
Claassen]; Leuctra tenuis [Pictet]); 4 species 
have possibly been extirpated (Isogenoides var- 
ians [Walsh]; Leuctra sibleyi Claassen; 
Nemocapnia Carolina Banks; Paracapnia angu- 
lata Hanson), and 1 rare species (Alloperla 
caudata Frison) is common. One species, 
Soyedina vallicularia [Wu], has been added to 
the state list. 

Data from over 50,000 Illinois stonefly spec- 
imens in the collections of the Illinois Natural 
History Survey are being analyzed to determine 
the species richness and spatial distribution of 
Illinois stoneflies by drainage basin. This assess- 
ment will be based separately on earlier data 
(Frison 1929, 1935, 1937, 1942; Ricker and 
Ross 1968, 1969; Ross and Ricker 1971) and 
will evaluate these data relative to collections 
since 1990. 

Apparent Trends 

In reevaluating the current status of Illinois 
stoneflies, our first concern was the status of so 
many "rare" species in Illinois. We wanted to 
determine if the limited locality records for 
these species reflect actual rare distribution in 
Illinois, inadequate sampling, or an accidental 
occurrence (i.e., the species is not normally a 
part of the indigenous Illinois fauna). It is now 
apparent that 13 of these species are truly rare in 
Illinois; many of these are at the edge of their 
distributions. The eastern deciduous forest with 
its gravel- and cobble-bottomed streams 
extends only slightly into Illinois and several of 
these rare species are found only in these habi- 
tats. Similarly, the limestone and sandstone 
outcroppings of the Shawnee Hills in southern 
Illinois offer another area of high-quality 
streams and are home for several rare species of 
Illinois stoneflies. To a very limited extent, 
springs in Illinois are a refugia for a few rare 
species. For only one species, Alloperla cauda- 
ta, does it appear that inadequate sampling dur- 
ing April and May produced a biased picture of 






Pteronarcys pictetii, one of the 
largest stoneflies in Illinois, is 
common to big rivers. In the 
nymphal stage, this species serves 
as an important food for fish. 



1X6 



Invertebrates — Our Living Resources 



Table . Relative abundance of 
Illinois stoneflies. R — rare (1-3 
localities); U — uncommon (4-14 
localities); and C — common 
(more than 14 localities). 
Surnames within or outside paren- 
theses refer to the authors of the 
species name. 



Species 



Relative abundance 



Group Euholognatha 



Capniidae 

Capniinae 

Allocapnia 

lorbesi Frison 
granulata (Claassen) 
illinoer.sis Frison 
mystica Frison 
nivicola (Fitch) 
recta (Claassen) 
rickeri Frison 
smithi Ross & Ricker 
vivipara (Claassen) 

Nemocapnia 

Carolina Banks 

Paracapnia 

angulata Hanson 



Leuctridae 

Leuctrinae 

Leuctra 

rickeri James 
sibleyi Claassen 
tenuis (Pictet) 

Zealeuctra 

claasseni (Frison) 
fraxina Ricker & Ross 
narfi Ricker & Ross 



Nemouridae 

Amphinemurinae 
Amphinemura 

delosa (Ricker) 

nigritta (Provancher) 

varshava (Ricker) 
Nemourinae 
Nemoura 

trispinosa Claassen 
Prostoia 

completa (Walker) 
Shipsa 

rotunda (Claassen) 
Soyedina 

vallicularia (Wu) 




Taeniopterygidae 
Brachypteryinae 

Strophopteryx 

lasciata (Burmeister) 
Taeniopteryginae 
Taeniopteryx 

burksi Ricker & Ross 

lita Frison 

metequi Ricker & Ross 

nivalis (Fitch) 

parvula Banks 
Group Systellognatha 



Chloroperlidae 

Chloroperlinae 

Alloperla 

caudata Frison 
roberti Surdick 

Haploperla 

brevis (Banks) 




Perlidae 

Perlinae 

Acroneuriinae 

Acroneuriini 
Acroneuria 

abnormis (Newman) 
evoluta Klapalek 
filicis Frison 
frisoni Stark and Brown 
internata (Walker) 
perplexa Frison 






U 
R 
C 

u 

R 



Species 


Relative abundance 


Attaneuna 


ruralis (Hagen) 


C 


Perlesta 


decipiens (Walsh) 


C 


Perlinella 


drymo (Newman) 


U 


ephrye (Newman) 


u 


Perlinae 


Neoperlini 


Neoperla 


clymene (Newman) complex 


c 


Perlini 


Agnelina 


flavescens (Walsh) 


c 


Paragnetina 


kansensis (Banks) 


u 


media (Walker) 


R 


Perlodidae 


Isoperlinae 


Clioperla 


clio (Newman) 


c 


Isoperla 


bilineata (Say) 


c 


burksi Frison 


R 


conspicua Frison 


R 


decepta Frison 


C 


longiseta Banks 


u 


marlynia (Needham & Claassen) 


R 


mohri Frison 


R 


nana (Walsh) 


C 


richardsoni Frison 


U 


Perlodinae 


Perlodini 


Hydroperla 


crosbyi (Needham & Claassen) 


U 


fugitans (Needham & Claassen) 


U 


Isogenoides 


varians (Walsh) 


R 


Pteronarycidae 


Pteronarcyinae 


Pteronacrcyini 


Pteronarcys 


picletii Hagen 


C 



its distribution, as this species is found com- 
monly across the Shawnee Hills. The apparent 
or possible extirpation of 10 species of stone- 
flies from Illinois creates serious concern. None 
of the species were collected in Illinois during 
1990-94, although we are still unsure about the 
extirpation of four of these species, since they 
are large-river species and we are not satisfied 
with our collecting techniques for these habitats. 
In evaluating the changes in spatial distribu- 
tion of Illinois stoneflies, the "winter stone- 
flies," in particular, the genus Allocapnia, offer 
the best examples (Frison 1929. 1935. 1937, 
1942; Ricker and Ross 1968, 1969; Ross and 
Ricker 1971; Webb and Harris 1993). One strik- 
ing example is A. granulata. In the 1920's, 30's, 
and 60's, this species was distributed and abun- 
dant from southeastern to northern Illinois. A 
drastic reduction in the distribution of this 
species has occurred since 1970, and in the past 
4 years, this species has only been collected 
within the Rock River drainage of northern 



Our Living Resources — Invertebrates 



187 



Illinois. As yet, no cause for this reduced distri- 
bution has been proposed. This is the most spec- 
tacular example we have discovered, but similar 
distribution patterns have been noted in other 
species, particularly within the genus 
Acroneuria. Our recent collections reveal that 
generalist species — those tolerant of a variety of 
environmental perturbations — apparently are 
becoming the dominant species in Illinois. 
Allocapnia vivipard, Taeniopteryx burksi, and 
Isoperla bilineata are examples of this trend; all 
are widespread throughout Illinois in many eco- 
logical habitats. 

References 

Frison, T.H. 1929. Fall and winter stoneflies. or Plecoptera. 
of Illinois. Bull, of the Illinois Natural History Survey 
18:345-409. 



Frison, T.H. 1935. The stoneflies, or Plecoptera. of Illinois. 
Bull, of the Illinois Natural History Survey 20:281-471. 

Frison, T.H. 1937. Studies of Nearctic insects. II. 
Descriptions of Plecoptera. with special reference to the 
Illinois species. Bull, of the Illinois Natural History 
Survey 21:78-99. 

Frison, T.H. 1942. Studies of North American Plecoptera, 
with special reference to the fauna of Illinois. Bull, of the 
Illinois Natural History Survey 22:235-355. 

Ricker, W.E., and H.H. Ross. 1968. North American species 
of Taeniopteryx (Plecoptera: Insecta). Journal of the 
Fisheries Research Board Canada 25:1423-1439. 

Ricker, W.E., and H.H. Ross. 1969. The genus Zealeuctra 
and its position in the family Leuctridae (Plecoptera, 
Insecta). Canadian Journal of Zoology 47: 1 1 1 3- 1 1 27. 

Ross, H.H., and W.E. Ricker. 1971. The classification, evo- 
lution, and dispersal of the winter stonefly genus 
Allocapnia. University of Illinois Biology Monographs 
45:1-162. 

Webb, D.W., and M.A. Harris. 1993. Survey of 21 rare 
species of stoneflies (Plecoptera) in Illinois. Illinois 
Natural History Survey, Center for Biodiversity Tech. 
Rep. 1993(3):1-14. 



For further information: 

Donald W. Webb 

Illinois Natural History Survey 

Center for Biodiversity 

607 East Peabody Dr. 

Champaign, IL 61820 



■ 








nn 



VnnHH 



P/awto 



Overview 



This section describes 
trends in two of the major 
kingdoms of life on earth: the green plants of 
the Kingdom Plantae and the molds, lichens, 
and mushrooms of the Kingdom Fungi. 
Members of the plant and fungal kingdoms have 
both economic and ecological importance. Plants 
transform solar energy into usable economic 
products essential in our modern society and 
provide the basis for most life on earth by gen- 
erating oxygen as a product of photosynthesis. 
Fungi not only mediate critical biological and 
ecological processes including the breakdown 
of organic matter and recycling of nutrients, but 
they also play important roles in mutualistic 
associations with plants and animals. Members 
of the Kingdom Fungi also produce commer- 
cially valuable substances including antibiotics 
and ethanol, while other fungi are pathogenic 
and cause damage to crops and forest trees. 
Because fungi and plants play such fundamen- 
tal roles in our lives, it is important to have a 
comprehensive knowledge of the taxa com- 
prising these groups. However, at a time 
when we are increasingly recognizing the 
importance of these groups, we are impoverish- 
ing our biological heritage. Rates of species loss 
are reaching alarming levels as ecosystems are 
degraded and habitat is lost. This erosion of bio- 



logical diversity threatens the maintenance of 
long-term sustainable development and protec- 
tion of the earth's biosphere. 

Questions involving biological diversity are 
now of major concern to scientists, the general 
public, and government agencies with mandates 
for natural resource protection. Much of this 
concern has been directed toward tropical forest 
systems because of their high levels of biodi- 
versity, although other regions, including the 
United States, deserve our immediate attention. 
Certainly, a first step toward conserving biolog- 
ical diversity must be based on a firm knowl- 
edge of the numbers and distribution of existing 
species. Developing good estimates of species 
diversity is also important in describing histori- 
cal and current trends of species dynamics. 
Unfortunately, despite the existence of various 
state and regional surveys, the efforts of taxon- 
omists and natural historians, and the publica- 
tion of various floras, we still do not have pre- 
cise estimates of the status of plant and fungal 
taxa in the United States. Estimates for vascular 
plant taxa in the United States range upward 
from 17,000 species (Morin, Morse et al., this 
section). In contrast to this well-studied group, 
only 5%-10% of an estimated 1.5 million fungal 
species have been described worldwide 
(Rossman, this section). 



by 
Science Editor 

Glenn R. 

Guntenspergen 

National Biological 

Service 

Southern Science Center 

700 Cajundome Boulevard 

Lafayette, LA 70506 



190 



Plants — Our Living Resources 



Even though the bulk of information about 
our native vascular flora was collected in the 19th 
and early 20th centuries, significant data about 
the status of plants in the United States continue 
to be collected as species expand their ranges, as 
other species thought locally extirpated are redis- 
covered, as poorly surveyed areas are explored, 
and as species become extinct. Even in states like 
New York, which has a long and currently active 
program of botanical exploration, additional 
species of vascular plants continue to be docu- 
mented as poorly surveyed areas are given more 
comprehensive coverage (Miller and Mitchell, 
this section). 

Herbaria and museums continue to be impor- 
tant repositories for this information because 
collecting by their personnel represents a signif- 
icant effort at inventorying plant and fungal 
species in this country (Morin, this section). 
Unfortunately, their role is increasingly at risk as 
support for collecting declines. In other cases, a 
shortage of trained specialists will prevent an 
adequate inventory of biotic diversity. Although 
many regional checklists exist as well as excel- 
lent manuals that cover bryophyte systematics, 
floristic inventories of bryophytes have been 
hampered primarily by a lack of trained profes- 
sionals (Merrill, this section). 

The flora of the American countryside has 
been much changed since European settlement. 
Over the past 20 years alone, more than 200 
species of non-native vascular plants have been 
recorded in New York state; these species repre- 
sent an important risk to native plant communi- 
ties (Miller and Mitchell, this section). Human 
activities are responsible for the introduction of 
these invasive exotics as well as the extinction of 
some species with small geographic ranges or 



those restricted to unique habitats. 

If current trends in land-use continue, how- 
ever, even species with more widespread distri- 
butions will be at risk. For example, lichens as a 
group are declining in many areas from the 
effects of air pollution. It is estimated that as 
much as 80%-90% of the original lichen flora 
has disappeared from urbanized areas (Bennett, 
this section). Likewise, marked declines in 
macrofungi have been documented in Europe 
although similar trends in this country have not 
been published because, in part, of the incom- 
plete inventory and lack of monitoring of these 
groups in the United States (Mueller, this sec- 
tion). Among the more completely documented 
vascular plants, The Nature Conservancy reports 
that 9.8% of native species have been lost from 
at least one state, more than 200 native species 
have become extinct in the United States, and an 
additional 403 native plant taxa need protection 
under the United States Endangered Species Act 
(Morse et al., this section). 

The articles in this section represent an 
important step in describing the status of the 
plant and fungal taxa in this country. They pro- 
vide a snapshot illustrating our knowledge of 
past and current distributions of plants; the 
importance of developing a more comprehen- 
sive data base for various groups, especially the 
fungi; and the need to develop a comprehensive 
inventory of the continually changing and evolv- 
ing flora of the United States. If we are to under- 
stand the causes underlying the changes in pat- 
terns of diversity and make predictions about the 
threats of anthropogenic (human-caused) activi- 
ties, we must have a quantitative understanding 
about the nature and distribution of the taxa 
composing our flora. 



Microfungi: 
Molds, 
Mildews, 
Rusts, and 
Smuts 



Amy Y. Ross man 

U.S. Department of 

Agriculture 



Fungi are a group of organisms that exist as a 
vast network of tiny threads growing in and 
out of all kinds of organic matter. As they grow, 
the threads secrete enzymes that break down the 
substances around them, releasing nutrients into 
the environment. Without fungi, the world would 
be completely covered with organic debris that 
would not rot, and nutrients would not be avail- 
able for plant growth. All plants would die. 

Microfungi include the organisms that are 
called molds and mildews as well as rusts and 
smuts, which cause plant diseases. They grow in 
all substrates, including plants, soil, water, 
insects, cows' rumen (see glossary), hair, and 
skin. Microfungi are said to be small because 
only part of the fungus is visible at one time, if 
at all. The visible parts produce thousands of 
tiny spores that are carried by the air, spreading 
the fungus. Most of the fungal body consists of 
microscopic threads extending through the sub- 
strate in which it grows. The invisible fungal 



structure may be extremely large, often extend- 
ing for miles as, for example, the "humongous 
fungus" occurring in the north-central United 
States (Rensberger 1992). 

Among the multitudinous molds are humble 
servants such as Penicillium notation, the source 
of penicillin, and Tolyposporium niveum, a pro- 
ducer of cyclosporin, the immune-system sup- 
pressant used for organ transplant operations. In 
sustainable agriculture the fungal performers are 
agents of biological control and crop nutrition, 
helping the environment through the reduced 
use of chemical pesticides and fertilizers. Fungi 
can stop a hoard of locusts by attacking the 
chitinous insect exoskeleton or control nema- 
todes that destroy the roots of crop plants (CAB 
1993). Although strains of fungi can degrade 
plastics and break down hazardous wastes such 
as dioxin (Jong and Edwards 1991), only a frac- 
tion of these fungi have been screened as bene- 
ficial organisms. 



Our Living Resources — Plants 



191 



Microfungi can also be harmful, causing the 
irritating human affliction known as athlete's 
foot as well as disastrous diseases of crops and 
trees. The potato famine in Ireland during the 
mid- to late 1800's was caused by a fungus 
called Phytophthora infestans that rotted the 
potato crops for several years (Large 1962). 
Because of this disease, many Irish immigrated 
to the United States. Once the nature of the dis- 
ease was determined, a solution based on fungus 
control was found. Knowing what fungi exist, 
where they occur, and what they do is essential. 

Diversity of Microfungi 

The microfungi are the most diverse group of 
all the fungi but the least understood or docu- 
mented. Only about 5%-10% of all fungal 
species have been described, much less charac- 
terized and put to use or controlled. 
Investigations to explore the diversity of micro- 
fungi have shown that they are much more 
diverse than previously thought. Very small sam- 
ples of tropical rainforest leaf litter yielded up to 
145 different species of microfungi (Bills and 
Polishook 1994). About 200,000 fungal species 
have been described worldwide (Reed and Farr 
1993), yet an estimated 1-1.5 million species 
may exist (Hawksworth 1991; Rossman 1994). 

Within the United States, information has 
been published about 13,000 species of micro- 
fungi on plants or plant products (Farr et al. 
1989), probably only a fraction of the species 
thought to exist. Specimens of microfungi are 
housed in the U.S. National Fungus Collections 
and other institutions that serve as reservoirs of 
information and documentation about our 
nation's natural heritage. By comparing the 
species reported in the literature with those rep- 
resented in the collections, one can estimate the 
number of microfungi known in the United States 
at 29,000 species (Farr et al. 1989). In areas of the 
world where fungi have been well studied, the 
ratio of vascular plants to fungi is about 6 to 1, 
suggesting that there may actually be 120,000 
species of fungi within the United States. 

Internet Information 

Although the numbers and kinds of fungi in 
the United States are not known, information 
about the microfungi associated with plants and 
plant products in the United States is available 
over Internet at this telnet address: 
FUNGI.ARS-GRIN.GOV After the word OK 
appears on the screen, type login user; when 
prompted for a password, type user. By doing 
this, anyone can find out what fungi might occur 
on the flowers in his or her own backyard. Data 
can also be consulted on accurate scientific 



names of microfungi, recent literature on 
plant-associated fungi, specimens in the U.S. 
National Fungus Collections, and records of 
microfungi on plants throughout the world. In an 
instant, reports of fungi can be consulted by 
those making land-management decisions or 
helping a farmer control a disease. 

Survey and Inventory Needs 

Knowing which microfungi occur within the 
United States provides information upon which 
plant quarantine decisions are made. A wrong 
decision allowing entry of a harmful pathogen 
can profoundly affect this nation's biological 
resources. In the eastern United States, a devas- 
tating disease called chestnut blight, caused by 
Cryphonectria parasitica and unknowingly 
imported from Europe on logs, killed virtually 
all the towering chestnut trees that once domi- 
nated our forests in the last century 
(Anagnostakis 1987). Now on the forest floor 
only skeletons of the trees can be seen with 
decay fungi rotting the bleached "bones" of these 
fallen giants. 

Another disease, dogwood anthracnose, 
occurs on flowering dogwood trees in both the 
eastern and western United States. The causal 
fungus, Discula destructiva, was unknown until 
1991 (Redlin 1991). Still unknown is whether 
this fungus was imported or was already present 
in the United States before its appearance as dog- 
wood anthracnose. Because microfungi are 
small, their existence may not be noticed until 
they cause serious diseases. 

A program to inventory and monitor micro- 
fungi in the United States does not exist at pre- 
sent; thus it is impossible to determine if species 
of microfungi are increasing or declining. Efforts 
to document the biodiversity of microfungi in the 
United States are limited to reports by plant 
pathologists who encounter disease-causing 
organisms or search for useful biological-control 
organisms. Information about the occurrence and 
biology of microfungi will increase the ability to 
make accurate decisions about the importation of 
agricultural products, to control microfungi 
already present, and to determine if beneficial 
microfungi are being lost because of habitat 
destruction. With increased knowledge the unex- 
plored world of microfungi can be put to work to 
solve our most pressing environmental and agri- 
cultural problems. 

References 

Anagnostakis, S. 1987. Chestnut blight: the classical problem 
of an introduced pathogen. Mycologia 79( 1 ):23-37. 

CAB. 1993. Locust project enters phase two. Commonwealth 
Agricultural Bureau (CAB) International News. June. p. 4. 

Bills, G.F., and J.D. Polishook. 1994. Abundance and diver- 
sity of microfungi in leaf litter of a lowland rain forest in 
Costa Rica. Mycologia 86:187-198. 



192 



Plants — Our Living Resources 



For further information: 

Amy Y. Rossman 

U.S. Department of Agriculture 

U.S. National Fungus Collections 

Beltsville, MD 20705 



Farr, D„ G. Bills, G. Chamuris, and A. Rossman 1989. 

Fungi on plants and plant products in the United States. 

American Phytopathological Society Press, St. Paul, 

MN. 1,152 pp. 
Hawksworth, D.L. 1991. The fungal dimension of biodiver- 
sity: magnitude, significance, and conservation. 

Mycological Res. 95:641-655. 
Jong, S.C., and M.J. Edwards. 1991. American type culture 

collection catalogue of filamentous fungi, 18th ed. 

Rockville, MD. 667 pp. 
Large, E.C. 1962. Advance of the fungi. Dover, New York. 

488 pp. 



Redlin, S.C. 1991. Discula destructiva sp. nov.. cause of 
dogwood anthracnose. Mycologia 83:633-642. 

Reed, C.F., and D.F. Farr. 1993. Index to Saccardo's Sylloge 
Fungorum. Volumes I-XXVI IN XXIX 1882-1972. Reed 
Herbarium. Darlington. MD. 884 pp. 

Rensberger. B. 1992. Underground goliath. Michigan mush- 
room over 1,500 years old. Washington Post. April 2. 

Rossman. A.Y 1994. A strategy for an all-taxa inventory of 
fungal biodiversity. In C.I. Peng, ed. Biodiversity and ter- 
restrial ecosystems. Bull, of the Academy Sinica Institute 
Botany. In press. 



Macrofungi 



by 

Gregory M. Mueller 

The Field Museum, Chicago 




Fig. 1. Entoloma salmoneum. The 
salmon-colored entoloma is a 
common recycler of forest litter in 
North American forests. 



Macrofungi are a diverse, commonly 
encountered, and ecologically important group 
of organisms. Like most fungi, the major part of 
these organisms consists of a mass of thin, 
microscopic threads (termed mycelium) grow- 
ing in soil, decomposing leaves, and other sub- 
strate. They differ from other fungi by forming 
large, macroscopic fruitbodies at some time in 
their life; the mushrooms sold in grocery stores 
are an example of these fruitbodies. This group 
of fungi includes all mushrooms (Fig. 1), 
morels, puffballs, bracket fungi, and cup fungi. 

Macrofungi are vitally significant in forests; 
many species help break down dead organic 
material, such as dead tree trunks and leaves, 
into simple compounds usable by growing 
plants. Thus, they act as nature's recyclers, 
without which forests could not function. Some 
species are major plant pathogens (causes of 
disease) that cause millions of dollars of dam- 
age to U.S. forests each year. Still other species 
enter into a necessary, mutually beneficial asso- 
ciation with trees such as oaks, pines, firs, and 
spruces. In this association (Fig. 2), termed 
mycorrhizae, the mycelium of the fungus brings 
water and nutrients to the tree in return for tak- 
ing excess food from the tree. Neither the tree 
nor the fungus can survive without the other. 
Finally, some of these fungi form an important 
part of the diet of many small mammals and 
insects. For example, small truffle-like fungi are 
a major food source of the northern flying squir- 
rel (Glaucomys sabhnus; see box). Because 
macrofungi are an indispensable component of 
the forest ecosystem, information on which 
fungi occur in the forests and on the specific 



Fig. 2. Mycorrhizae formed 

between ponderosa pine and J 

Laccaria laccata in the laboratory. ^ 

Note the branched pine roots and I 

threadlike fungal hyphae. J 




role that they play is necessary for management 
and maintenance of our forests. 

Macrofungi also directly affect people. 
Though some fungi are deadly poisonous, oth- 
ers are prized as edibles. Commercial mush- 
room harvesting is a multimillion-dollar-a-year 
business in the United States; for example, the 
industry added an estimated $40 million to the 
Oregon economy in 1993 alone. Additionally, 
several thousand amateur mushroom hunters in 
the United States collect solely for their own 
enjoyment. 

Number of Species 

Considering the human, ecological, and eco- 
nomic importance of these organisms, it is 
somewhat surprising that there is not a good 
estimate of the number of species of macrofun- 
gi that occur in North America. Because there 
are neither checklists of North American mush- 
rooms and their relatives nor comprehensive 
regional treatments, the best estimates of North 
American diversity are based on comparisons 
with numbers of these organisms reported from 
Europe. More than 3,000 species of mushrooms 
and their relatives are reported from western 
Europe (Moser 1983), but most scientists who 
study fungi (mycologists) would estimate that 
far more species occur in North America. For 
example, more than twice as many species of 
Lactarius, Amanita, and Clitocybe are reported 
from the continental United States (Hesler and 
Smith 1979; Bigelow 1982, 1985; Jenkins 
1986) than from western Europe (Moser 1983). 

Better estimates exist for species diversity of 
the other groups of North American macrofun- 
gi. Gilbertson and Ryvarden (1986, 1987) treat- 
ed more than 400 species of polypore fungi. 
Smith et al. (1981) listed nearly 300 species of 
puffballs and relatives, and Seaver (1942, 1951) 
covered more than 350 species of cup fungi and 
other macro ascomycetes. Based on these data, 
it is reasonable to predict that there are 5,000- 
10,000 species of macrofungi in the United 
States. A compilation of herbarium records in 
U.S. and Canadian museums and universities 
would provide a good first step in predicting the 
diversity of these organisms. 



Our Living Resources — Plants 



193 




Fig. 3. Cantharellus cibarius. The chanterelle is one of the 
important fungi forming mycorrhizae with pines and oaks 
in North American forests. 

Declining Fungi 

Change in the frequency of occurrence of 
macrofungi in Europe is well documented; 
many species that form ectomycorrhizae (a kind 
of mycorrhizae; see glossary) are showing a 
marked decline, and some species involved with 
wood decay show a marked increase in fruiting. 
More than 50% of the reported species of mush- 
rooms in Europe occur on at least one country's 
"Red List" {see glossary: "red data book") 
(Arnolds and de Vries 1993), and once-common 
species such as Hydnum repandum and some of 
the chanterelles (Fig. 3) appear lost from some 



countries. Air pollution, particularly acid rain, 
has been implicated in this observed decline in 
ectomycorrhizal fungi fruiting frequency and 
diversity in Europe (Fellner 1993; Pegler et al. 
1993). Intensive collecting of edible fungi such 
as chanterelles, Hydnum, and boletes might also 
be negatively affecting fruiting patterns of these 
fungi, but additional data are needed to docu- 
ment this. In any case, the observed change in 
fungal fruiting is correlated with a decline in 
forest health, but cause and effect are hard to 
document. Rigorous studies to determine if sim- 
ilar trends in macrofungi fruiting patterns have 
occurred in the United States do not exist. 

Current Studies of Diversity 

The baseline data necessary for estimating 
fungal diversity and for investigating trends in 
fruiting patterns and frequencies of macrofungi 
in the United States and Canada are not yet 
available although various methods are begin- 
ning to be used to obtain these necessary data. 
For example, studies of species diversity and 
frequency of particular fungi in Pacific 
Northwest old-growth forests have documented 
that while a single season of collecting will 
uncover most of the decomposer macrofungi, 
mycorrhizal fungi fruit much more erratically 
(Vogt et al. 1992). Thus, to develop a reasonable 



Most Americans identify truffles as 
expensive, Epicurean delights from 
Europe, found with the aid of pigs. Because 
truffles are produced belowground, we 
remain ignorant of the rich diversity and 
importance of truffles in North America. 
Truffles (ascomycetes) and the similar- 
appearing false truffles (basidiomycetes) 
play a major role in determining the struc- 
ture and function of forest ecosystems by 
providing nutrients to many economically 
valuable trees in exchange for carbohydrates 
from the trees. This mycorrhizal (fungus 
root) symbiosis is obligate; that is, truffles 
and trees, especially conifers, cannot survive 
without each other. One of the problems in 
reforesting large areas of the Southwest is 
identifying ectomycorrhizal fungi suitable 
for inoculation of tree seedlings destined for 
sites with calcareous soils. 

Truffles and false truffles are food items 
for many animals, including many endan- 
gered or threatened species. In old-growth 
Douglas-fir (Pseudotsuga menziesii) forests, 
truffles not only provide soil nutrients to the 
trees controlling forest structure, but they 
also are an important link in the food web 
supporting the endangered spotted owl. 
Northern flying squirrels (Glaucomys sabri- 
nus) glide down to the forest floor at night to 



Truffles, Trees, and 
Biodiversity 

by 

Robert Fogel 

University of Michigan 



feed on truffles. While feeding on truffles, 
flying squirrels become vulnerable to preda- 
tion from the northern spotted owl (Strix 
occidentalis caurina), coyotes (Canis 
latrans), bobcats (Lynx rufus), and other 
predators. 

Given the undeniably important role of 
truffles in determining the structure and 
function of forest ecosystems, how much is 
known about the distribution of truffles and 
false truffles? The paucity of information 
and potential impact of surveys on our 
knowledge base can be illustrated by an 
ongoing National Science Foundation-fund- 
ed survey of the Great Basin, an area of 
712,250 km 2 (275,000 mi 2 ) between the 
Sierra Nevada and Wasatch mountains and 
including most of Nevada and parts of 



California, Idaho, Utah, Wyoming, and 
Oregon. No truffles or false truffles had been 
reported from the area before the survey. 
Over three summers, the survey produced 
1,1 19 collections of truffles and false truffles 
from 40 mountain ranges. 

In addition, the survey produced evi- 
dence for extinction of many truffles in the 
Great Basin. A few truffles obligately asso- 
ciated with a single tree species outside the 
Great Basin have switched within the Great 
Basin to new tree species, providing sup- 
porting evidence for extinction of local tree 
species. New endemic species have been 
found and the geographic ranges of some 
species greatly expanded. Populations of 
some endemic species are restricted to a sin- 
gle mountain range. 

Knowledge of truffles is important to the 
biodiversity in the United States. Without 
such knowledge, there is a danger of losing 
or degrading ecosystems through ignorance 
about the status of keystone fungal species. 
If ecosystems are lost, then species depen- 
dent on specific ecosystems will also be lost. 

For more information: 

Robert Fogel 
University of Michigan 
Ann Arbor, Ml 48109 



194 



Plants — Our Living Resources 



For further information: 

Gregory M. Mueller 
The Field Museum 

Department of Botany 
Chicago, IL 60605 



estimate of species richness and dominance, 
researchers must sample over several years. 
These studies also have documented that certain 
collecting techniques work better for some 
fungi than others, which emphasizes the need to 
develop standardized sampling protocols for 
collecting data on fungal species' richness and 
fruiting patterns. 

Satellite imagery has been combined with a 
long-term mapping program of fungal fruitbod- 
ies to assess the relative health and growth of 
particular tree-mycorrhiza fungus pairs in 
southern Mississippi (Cibula and Ovrebo 1988). 
This approach shows great promise for directly 
investigating the effect of certain fungi on tree 
health. These data, however, are based only on 
aboveground information, and there is still 
some question about how well the appearance 
of fruitbodies growing under a particular tree 
predicts what fungi are forming mycorrhizae 
with that tree at that time. To address this ques- 
tion, researchers have developed molecular 
techniques using DNA amplification proce- 
dures to compare the mycorrhizae on the roots 
of certain trees with fungal fruitbodies occur- 
ring near the tree (Bruns and Gardes 1993). The 
preliminary data documented that there is not 
always a one-to-one correlation between fruit- 
bodies and mycorrhizae, and that caution must 
be used when using fruitbodies alone. 

Further Studies 

The studies mentioned in this article illus- 
trate the range of work in the United States on 
assessing diversity and determining possible 
changes in fruiting patterns of macrofungi. 
More work is needed to document the status and 
trends of macrofungi in North America. These 
data are vital because of the integral role that 
macrofungi play in forest systems as decom- 
posers and recyclers, plant pathogens, mutual- 
ists, and food for small mammals, and because 
of the growing commercial importance of these 
fungi. 



References 

Arnolds. E.. and B. de Vries. 1993. Conservation of fungi 
in Europe. Pages 211-234 in D.N. Pegler. L. Boddy. B. 
Ing, and P.M. Kirk. eds. Fungi of Europe: investigation, 
recording and conservation. The Royal Botanic Gardens. 
Kew, U.K. 

Bigelow. H.E. 1982. North American species of Clitocybe. 
Part 1. Beihefte zur Nova Hedwigia 72:5-280. 

Bigelow, H.E. 1985. North American species of Clitocybe. 
Part 2. Beihefte zur Nova Hedwigia 81:281-471. 

Bruns, T., and M. Gardes. 1993. Molecular tools for the 
identification of ectomycorrhizal fungi: taxon-specific 
oligonucleotide probes for suilloid fungi. Molecular 
Ecology 2:233-242. 

Cibula. W.G., and C.L. Ovrebo. 1988. Mycosociological 
studies of mycorrhizal fungi in two loblolly pine plots in 
Mississippi and some relationships with remote sensing. 
Pages 268-307 in J.D. Greer, ed. Remote sensing for 
resource inventory, planning and monitoring. 
Proceedings of the Second Forest Service Remote 
Sensing Application Conference. American Society for 
Photogrammetry and Remote Sensing. Falls Church. VA. 

Fellner, R. 1993. Air pollution and mycorrhizal fungi in 
central Europe. Pages 239-250 in D.N. Pegler. L. Boddy. 
B. Ing. and P.M. Kirk. eds. Fungi of Europe: investiga- 
tion, recording and conservation. The Royal Botanic 
Gardens. Kew, U.K. 

Gilbertson. R.L., and L. Ryvarden. 1986. North American 
Polypores. Vol. 1. Fungiflora A/S. Oslo. 433 pp. 

Gilbertson, R.L., and L. Ryvarden. 1987. Pages 437-885 in 
North American Polypores. Vol. 2. Fungiflora A/S. Oslo. 

Hesler, L.R., and A.H. Smith. 1979. North American 
species of Lactarius. The University of Michigan Press, 
Ann Arbor. 841 pp. 

Jenkins, D.T 1986. Amanita of North America. Mad River 
Press, Eureka, CA. 198 pp. 

Moser, M. 1983. Keys to the Agarics and Boleti 
(Polyporales. Boletales. Agaricales. Russulales). Roger 
Phillips, London. 535 pp. 

Pegler, D.N.. L. Boddy. B. Ing. and P.M. Kirk, eds. 1993. 
Fungi of Europe: investigation, recording and conserva- 
tion. The Royal Botanic Gardens. Kew, U.K. 322 pp. 

Seaver, F.J. 1942. The North American cup fungi 
(Operculates). Rev. ed. Seaver, New York. Reprinted by 
Lubrecht and Cramer. 377 pp. + 74 plates. 

Seaver. F.J. 1951. The North American cup fungi 
(Inoperculates). Seaver. New York. 428 pp. 

Smith, A.H.. H.V Smith, and N.S. Weber. 1981. How to 
know the non-gilled fleshy fungi. 2nd ed. William C. 
Brown. Dubuque, IA. 324 pp. 

Vogt, K.A., J. Bloomfield. J.F. Ammirati. and S.R. 
Ammirati. 1992. Sporocarp production by 
Basidiomycetes. with emphasis on forest ecosystems. 
Pages 563-581 in G.C. Carroll and D.T. Wicklow, eds. 
The fungal community. Marcel Dekker. Inc.. New York. 



Lichens 



by 

James P. Bennett 

National Biological Service 



Lichens are a unique life form because they 
are actually two separate organisms, a fun- 
gus and an alga, living together in a symbiosis. 
Lichens seem to reproduce sexually, but what 
appears to be a fruiting structure is actually that 
of the fungal component. Consequently, lichens 
are classified by botanists as fungi, but are given 
their own lichen names. 

Lichens are small plant-like organisms that 
grow just about everywhere: soils, tree trunks 
and branches, rocks and artificial stones, roofs, 
fences, walls, and even underwater. They are 
famous for surviving climatic extremes and are 



even the dominant vegetation in those habitats. 
Some lichens, however, are only found in very 
specialized habitats. The diversity of lichens in 
an area, therefore, is highly dependent on habi- 
tat diversity. Many special habitats across the 
United States are declining or disappearing 
because of human activities, and some lichen 
species are consequently in decline. 

Lichens are very diverse in form: some grow 
Hat and appressed to a substrate, others are 
more leaf-like and grow free of the substrate, 
and yet others have complex filamentous and 
blade-like forms. 



Our Living Resources — Plants 



195 



Lichens are unique botanically because they 
lack any outside covering, or cuticle, and conse- 
quently are directly exposed to the atmosphere, 
which they depend upon for their nutrients and 
water, neither of which is derived from their 
hosts. Moistened lichen tissues act as blotters, 
soaking up chemicals or materials deposited on 
their surfaces. Unfortunately, this feature has 
also made them highly susceptible to air pollu- 
tants; lichens are perhaps the plant species most 
susceptible to sulfur dioxide, heavy metals, and 
acid rain. 

Lichens play important roles in ecosystems. 
They break down rocks and form soil by excret- 
ing weak acids, or in arid ecosystems like 
deserts, they help bind the soil surface by form- 
ing crusts. They are important food sources for 
invertebrates and vertebrates, including reindeer 
that eat reindeer "moss," which is actually a 
lichen (Fig. 1 ). In addition, some birds depend 
on certain lichens for nest-building materials. 
Finally, some lichens can fix nitrogen from the 
atmosphere and contribute a significant portion 
of this to certain forest ecosystems (e.g., the 
Pacific Northwest). 

A rich lichen flora in a region indicates a 
lack of disturbance in the area for two reasons. 
First, lichens can only appear in an area if both 
the fungus and alga are propagated there and 
coincide. Isolation of an area so that propagules 
(see glossary) cannot reach the area will slow 
down recolonization significantly. Second, 
lichens grow slowly, usually only a few mil- 
limeters a year. Thus, colonization of an area by 
lichen species typically does not occur even 
over the span of one human generation. 

Status 

The best estimates of the number of U.S. 
lichen species are between 3,500 and 4,000, 
grouped in about 400 genera. The current 
checklist for the United States and Canada is 
probably in excess of 3,600 (Egan 1987). 

Some species are cosmopolitan and are 
found from coast to coast. Most species, how- 
ever, are more limited in their geographic distri- 
butions. The percentage of species that are rare 
nationally is high: about one-third of more than 
400 lichens described by Hale (1979) are rare, 
and this ratio could probably be applied to the 
total number for the United States. Thirty-eight 
percent of the lichen flora of Hawaii is consid- 
ered endemic. Five lichen species have been 
nominated for federal threatened and endan- 
gered listing (Pittam 1991), and several states 
(e.g., California, Minnesota, and Missouri) have 
listed some species as threatened or endan- 
gered. 

No state has a complete lichen flora pub- 
lished. Incomplete floras or checklists are 




Fig. 1. Cladinu mitis and C. 
rangiferina (reindeer moss), 
Voyageurs National Park. MN. 



known for Alaska, California, Colorado, 
Connecticut, Florida, Hawaii, Louisiana, 
Michigan, Minnesota, North Carolina, New 
Mexico, New York, South Dakota, Tennessee, 
Texas, and Washington. Most of the rest of the 
country's lichen flora remains unexplored. 
Species for these partial checklists number in 
the several hundreds, with the exception of 
California with 999 taxa. Nationally, centers of 
diversity for lichens include the Pacific 
Northwest, California, the southern 
Appalachians, Florida, and Maine. On a more 
local scale, wetlands and floodplains tend to 
have higher numbers of lichen species than 
more arid areas. The presence of a bog or a 
rocky outcropping in an area will typically dou- 
ble the number of species present. 

There are about 10 lichen herbarium collec- 
tions with active lichen taxonomists in the 
United States, and about 5 in Canada. Many of 
these collections are poorly funded, not com- 
puterized, and stored in inadequate or outdated 
facilities. Fewer than two dozen practicing 
lichenologists work in the United States and 
Canada, and very few graduate students are 
being trained in lichenology. Most academic 
botany or biology departments do not have 
lichenologists. 

Trends 

About 100 years ago, lichens had disap- 
peared from many cities in Europe and Great 
Britain and the term "lichen desert" was coined 
to describe the phenomenon; these lichen 
deserts were caused by air pollution. Here in the 
United States, lichen deserts are well known in 
our cities and nearby rural areas, but are unfor- 
tunately poorly documented. Most information 
is anecdotal, but some studies have shown 
lichen deserts in eastern Pennsylvania (Nash 
1975), the Cuyahoga Valley in Ohio (Wetmore 
1989), northern Indiana on Lake Michigan 
(Wetmore 1988), Cedar Rapids, Iowa (Saunders 
1976), Los Angeles (Sigal and Nash 1983), 
Seattle, Washington (Johnson 1979), 



196 



Plants — Our Living Resources 




Fig. 2. Documented lichen deserts 
in the United States and Canada. 
Strong anecdotal evidence exists 
that lichen deserts also occur in 
most major cities. 



For further information: 

James P. Bennett 

National Biological Service 

Wisconsin Cooperative 

Research Unit 

University of Wisconsin-Madison 

Madison, WI 53705 



Copperhill, Tennessee (Mather 1978), and in 
Canada in Montreal (LeBlanc and De Sloover 
1970) and Sudbury (LeBlanc et al. 1972) (Fig. 
2). In some of these areas, researchers estimate 
that as much as 80%-90% of the original lichen 
flora is gone (Nash 1975; Wetmore 1989). Acid 
rain has diminished lichen diversity in remote 
rural areas such as north-central Pennsylvania 
(Showman and Long 1992), central and south- 
western Connecticut (Metzler 1980), and south- 
western Louisiana (Thompson et al. 1987). 
Sensitive species must be studied and moni- 
tored to determine the effects of air pollutants. 

Some lichens are unique to old-growth 
forests. Usnea longissima, which only grows in 
old-growth spruce forests, has vanished from 
many sites in western Europe (Esseen et al. 
1992) and may be repeating this pattern in parts 
of the United States. Other old-growth forest 
lichens, including Alectoria sarmentosa, 
Lobaria scrobiculata, and Ramalina thrausta, 
are now quite rare in the eastern United States 
because of habitat destruction and loss. 

In addition, scientific overcollecting may 
become a problem for lichens. One species, 
Gymnoderma lineare, was overcollected in 
Great Smoky Mountains National Park, 
Tennessee, in the late 1970's, and is now pro- 
posed for federal listing as endangered. 
Collecting is no longer allowed in certain areas 
(e.g., some national parks and nature preserves), 
and both the American Bryological and 
Lichenological Society and the British 
Lichenological Society do not always permit 
collecting at popular sites during their annual 
forays. Some hobby overcollecting of lichens 
for dye materials or architectural tree models is 
thought to be a problem in a few areas, but is not 
well documented. 

Trends in lichenology in this country are not 
encouraging and are at odds with trends in the 
rest of world (Galloway 1992). With fewer uni- 
versities offering training in the discipline. 



fewer surveys and lists of floras being done, less 
literature being published, and at the same time 
lichens disappearing from our ecosystems, it is 
clear that the science is heading the opposite 
direction of what is needed. Other countries, 
including England, Canada, the Netherlands, 
and Japan, are increasing funding for lichenolo- 
gy, training more students, publishing more lit- 
erature, and conserving their lichen flora. Given 
the problems confronting lichen habitats, the 
size of the United States, and the potential flora 
it may have, lichen science needs more atten- 
tion. A reasonable start would be a preliminary 
checklist for every state and an identification of 
priority areas for future surveys. 

References 

Egan. R.S. 1987. A fifth checklist of the lichen-forming, 
lichenocolous and allied fungi of the continental United 
States and Canada. Bryologist 90:77-173. 

Esseen, P.-A., B. Ehnstrom, L. Ericson, and K. Sjoberg. 
1992. Boreal forests — the focal habitats of fennoscandia. 
Chapter 7 in L. Hansson, ed. Ecological principles of 
nature conservation. Elsevier. London. 

Galloway, D.J. 1992. Biodiversity: a lichenological per- 
spective. Biodiversity and Conservation 1:312-323. 

Hale, M.E. 1979. How to know the lichens. 2nd ed. Wm. C. 
Brown Publishers, Dubuque, IA. 246 pp. 

Johnson, D.W. 1979. Air pollution and the distribution of 
corticolous lichens in Seattle, Washington. Northwest 
Science 53(4):257-263. 

LeBlanc, F.. and J. De Sloover. 1970. Relation between 
industrialization and the distribution and growth of epi- 
phytic lichens and mosses in Montreal. Canadian Journal 
of Botany 48:1485-1496. 

LeBlanc, F, D.N. Rao, and G. Comeau. 1972. The epiphyt- 
ic vegetation of Populus balsamifera and its significance 
as an air pollution indicator in Sudbury, Ontario. 
Canadian Journal of Botany 50:519-528. 

Mather. T.C. 1978. Lichens as indicators of air pollution in 
the vicinity of Copperhill. Tennessee. Georgia Journal of 
Science 36:127-139 

Metzler, K.J. 1980. Lichens and air pollution: a study in 
Connecticut. Report of Investigations 9. State Geological 
and Natural History Survey of Connecticut. 30 pp. 

Nash, T.H.. III. 1975. Influence of effluents from a zinc fac- 
tory on lichens. Ecological Monographs 45:183-198. 

Pittam. S.K. 1991. The rare lichens project, a progress 
report. Evansia 8:45-47. 

Saunders, J.R. 1976. The influence of SO, on corticolous 
lichens in Cedar Rapids, Iowa. Submitted in partial ful- 
fillment for College Honors (Biology) at Coe College. 
Cedar Rapids, I A, May 1976. 1 1 1 pp. 

Showman. R.E., and R.P. Long. 1992. Lichen studies along 
a wet sulfate deposition gradient in Pennsylvania. 
Bryologist 95:166-170. 

Sigal, L.L.. andT.H. Nash III. 1983. Lichen communities on 
conifers in southern California mountains: an ecological 
survey relative to oxidant air pollution. Ecology 64: 1 343- 
1354. 

Thompson. R.L., G.J. Ramelow, J.N. Beck, M.P. Langley, 
and J.C. Young. 1987. A study of airborne metals in 
Calcasieu Parish. Louisiana using the lichens. Parmelia 
pmesorcdiosa and Ramalina stenospora. Water, Air and 
Soil Pollution 36:295-309. 

Wetmore. CM. 1988. Lichens and air quality in Indiana 
Dunes National Lakeshore. Mycotaxon 33:25-39. 

Wetmore, CM. 1989. Lichens and air quality in Cuyahoga 
Valley National Recreation Area, Ohio. Bryologist 
92:273-281. 



Our Living Resources — Plains 



197 



Bryophytes (mosses, liverworts, and horn- 
worts) are small green plants that reproduce 
by means of spores (or vegetatively) instead of 
seeds. Most are only a few centimeters high, 
although some mosses attain a half meter (20 in) 
or more. Although often small and inconspicu- 
ous, bryophytes are remarkably resilient and suc- 
cessful. They are sensitive indicators of air and 
water pollution, and play important roles in the 
cycling of water and nutrients and in relation- 
ships with many other plants and animals. 
Information about bryophytes and their ecology 
is essential to develop comprehensive conserva- 
tion and management policies and to restore 
degraded ecosystems. 

There are three main groups of bryophytes: 
mosses (Musci); liverworts, also known as hepat- 
ics (Hepaticae); and hornworts (Anthocerotae). 
Bryophytes rank second (after the flowering 
plants) among major groups of green land plants, 
with an estimated 15,000-18,000 species world- 
wide. In North America north of Mexico, there 
are 1,320 species of mosses in 312 genera 
(Anderson et al. 1990), and 525 species of hepat- 
ics and hornworts in 119 genera (Stotler and 
Crandall-Stotler 1977), or somewhat more than 
10% of the world's bryophyte species. 

Mosses are most abundant and conspicuous in 
moist habitats, but are also found in grasslands 
and deserts, where they endure prolonged dry 
periods. Hepatics also include some arid-adapted 
species, but most are plants of humid environ- 
ments. In mosses and leafy hepatics, the conspic- 
uous plant body is leafy; in some liverworts and 
all hornworts, the plant is a flattened, ribbon-like 
"thallus" that lies flat on the ground. Bryophytes 
have no roots but are anchored by slender threads 
called rhizoids, which also play a role in the 
absorption of water and mineral nutrients. 

Bryophytes have successfully exploited many 
environments, perhaps partly because they are 
rarely in direct competition with higher plants 
(Anderson 1980). For such small organisms, the 
climate near the ground (microclimate) is often 
very different from conditions recorded by stan- 
dard meteorological methods, and shifts in tem- 
perature and humidity are often extreme. A 
remarkable adaptation of bryophytes is their abil- 
ity to remain alive for long periods without water, 
even under high temperatures, then resume pho- 
tosynthesis within seconds after being moistened 
by rain or dew. 

Ecological Roles 

Most bryophytes appear to absorb water and 
mineral nutrients directly into leaves and stems, a 
fact that makes them extremely vulnerable to air- 
borne pollutants in solution (see references in 
Longton 1980). Where abundant, bryophytes 



may constitute an important sink for moisture 
and nutrients. Mosses are reliable indicators of 
soil conditions because they tend to accumulate 
chemical elements somewhat indiscriminately. 
The analysis of concentrations of pollutants in 
older bryophyte specimens could be used to doc- 
ument increases in pollution levels over time. 

Bryophytes are also closely associated with 
organisms as diverse as protozoa, rotifers (micro- 
scopic aquatic animals), nematodes, earthworms, 
mollusks, insects, and spiders (Gerson 1982), as 
well as plants and fungi. Direct interactions of 
bryophytes include providing food, shelter, and 
nesting materials for small mammals and inverte- 
brates; indirectly, they serve as a matrix for a 
variety of interactions between organisms. 

Bryophytes occur in all types of environ- 
ments, except salt water. They occur on both 
shaded and exposed soil and rocks, the bark of 
living trees, and on decaying logs and litter in 
humid forests (evergreen and deciduous). Many 
are subaquatic in swamps, bogs, and fens, and 
some grow submerged or emergent in streams. 
There are no marine bryophytes, but a few grow 
on coastline rocks and can tolerate exposure to 
salt spray. 




In the moss-carpeted rainforests of the Pacific 
Northwest, bryophytes make up a significant pro- 
portion of the biomass. Peat moss (Sphagnum) is 
a dominant organism in northern peatland com- 
munities and is of some economic importance in 
horticulture and as an energy source. Bryophytes 
of arid grasslands and deserts are few, but there 
are mosses that appear adapted to prairies and to 
the periodic intense disturbance of grazing and 
fire (Merrill 1991). 

Floristics and Distribution 

Basic information on the distribution of 
bryophytes is available for at least the northeast- 
ern United States, eastern Canada, and the Pacific 



Bryophytes 



by 

Gary L. Smith Merrill 

The Field Museum, Chicago 



The newly discovered moss genus 
and species. Ozobryum ogalalense, 
is known only from four localities 
in northwest Kansas and adjacent 
Nebraska (Merrill 1992). The 
species forms soft, compact cush- 
ions on exposed lime-rich outcrops 
in native prairie pastures. The out- 
crops are porous and charged with 
moisture, making them a magnet 
for several species of bryophytes in 
an otherwise hostile environment. 
Ozobryum underscores the fact that 
discoveries can still be made in 
areas of the country where 
bryophytes are poorly known. 



198 



Plants — Our Living Resources 



For further information: 

Gary L. Smith Merrill 

The Field Museum 

Department of Botany 

Roosevelt Rd. at Lakeshore Dr. 

Chicago, IL 60605 



Northwest. Some parts of the continent are less 
well known, chiefly remote areas of the Rockies, 
the arid Southwest, and the Great Plains. Much 
information about the bryophytes of the interior 
plains may be "irretrievably lost since most of the 
natural grassland, with whatever mosses it may 
have sheltered, is under cultivation" (Schofield 
1980, p. 131), but fieldwork can still yield impor- 
tant discoveries (Merrill 1992) as well as basic 
distributional information. 

A much-improved picture of bryophyte distri- 
bution in North America will emerge as the result 
of the preparation of treatments for Volume 13 of 
Flora North America (scheduled for publication 
in 1996), but much of the necessary distribution- 
al information is simply not available now. 

Status 

Some bryophyte species appear to thrive in 
disturbed habitats (both "naturally" disturbed and 
those due to human activity). Many bryophytes, 
however, are quite rare, have extremely local dis- 
tributions, and are at risk. Changes in land use and 
loss of habitat represent the greatest threat to 
bryophyte diversity. Cutting forests, draining bogs 
and wetlands, and destroying rock faces by quar- 
rying and road building are especially destructive. 

Most bryophytes are unlikely to be picked for 
their own sake, but where mosses are particularly 
abundant, as in the Pacific Northwest, commercial 
harvesting for horticultural purposes can have a 
significant effect. The loss of bryophyte habitat is 
likely to have a ripple effect, since other organ- 
isms closely associated with them are also likely 
to be lost. Efforts at habitat restoration must take 
into account the difficulty of re-creating the spe- 
cialized conditions that many bryophytes require. 

Future Needs and Priorities 

Basic floristic inventories are an essential part 
of any assessment of the role of bryophytes in nat- 
ural ecosystems. While checklists are available 
that cover the whole of North America (as well as 



many states), and floristic works are available that 
make the task of identifying species easier, these 
do not provide information on the status of indi- 
vidual species. Inventories are needed to identify 
areas where many rare bryophytes occur; these 
areas should be given priority in establishing con- 
servation reserves. In addition, trained specialists 
are scarce, and their numbers are decreasing. The 
advent of modern electronic data-base technology 
makes it possible to capture important distribu- 
tional information contained in existing collec- 
tions, but this also is time-intensive and expen- 
sive. Priorities are to support basic floristic 
research on bryophytes (and the training of new 
bryologists and information specialists needed to 
deal with the formidable task of documenting 
bryophyte diversity) and to provide support to 
institutions that maintain the major national 
resource collections of bryophytes. 

References 

Anderson, L.E. 1980. Cytology and reproductive biology of 

mosses. Pages 37-76 in R.J. Taylor and A.E. Leviton. eds. 

The mosses of North America. Pacific Division of the 

American Association for the Advancement of Science. 

San Francisco. 
Anderson. L.E.. H.A. Crum. and W.R. Buck. 1990. List of the 

mosses of North America north of Mexico. Bryologist 

93:448-499. 
Gerson, U. 1982. Bryophytes and invertebrates. Pages 291- 

332 in A.J.E. Smith, ed. Bryophyte ecology. Chapman and 

Hall, New York. 
Longton, R.E. 1980. Physiological ecology of mosses. Pages 

77-1 13 in R.J. Taylor and A.E. Leviton, eds. The mosses of 

North America Symposium. Pacific Division. American 

Association for the Advancement of Science. San 

Francisco. 
Merrill. G.L. Smith. 1991. Bryophytes of Konza Prairie 

Research Natural Area. Kansas. Bryologist 94:383-391. 
Merrill. G.L. Smith. 1992. Ozobryum ogalalense (Pottiaceae). 

a new moss genus and species from the American Great 

Plains. Novon 2:256-258. 
Schofield, W.B. 1980. Phytogeography of the Mosses of 

North America (north of Mexico). Pages 131-170 in R.J. 

Taylor and A.E. Leviton, eds. The mosses of North 

America. Pacific Division of the American Association for 

the Advancement of Science. San Francisco. 
Stotler. R.. and B. Crandall-Stotler. 1977. A checklist of the 

liverworts and hornworts of North America. Bryologist 

80:405-428. 



Floristic 
Inventories of 
U.S. 
Bryophytes 

by 

Alan Whittemore 

Bruce Allen 

Missouri Botanical Garden, 

St. I Amis 



Few floristic inventories of bryophytes have 
been made in the United States, primarily 
because of lack of trained personnel. The publi- 
cation of modern manuals for the eastern United 
States for mosses (Crum and Anderson 1981) 
and liverworts and hornworts (Schuster 
1966-92) has improved the situation. The pauci- 
ty of manuals in the western United States is 
especially critical because of the uniqueness of 
the western North American flora. Eighty per- 
cent of the genera of bryophytes known to be 
endemic to temperate North America are con- 
fined to the area west of the 110th meridian 



(approximately the Rocky Mountains and 
west), but very few bryologists work there 
(Schofield 1980; Schuster 1984). 

Mosses 

Mosses are the best known of the three 
bryophyte groups and have the most species: 
1,320 species in 312 genera (Anderson et al. 
1990). The only manual of mosses that treats all 
o\~ North America north of Mexico is by A.J. 
Grout (1928-40), but is now outdated. Although 
this flora is unreliable for the mosses in the 



Our Living Resources — Plains 



199 




WrW6 •>. -!.vii>*>« 

The moss Leucolepis acanthoneuron. 

midcontinent, it covers the mosses from the 
eastern United States and the west coast regions 
well. 

The eastern forest region is the strongest 
area for moss floristics in the United States. The 
United States east of the Mississippi is covered 
well by Crum and Anderson's (1981) flora. 
Most states there have recent checklists of 
mosses. In addition, several regional floras 
cover parts of more than one state (e.g., Crum 
[1983] for upper Michigan and nearby areas and 
Redfearn [1983] for the Ozark region). 

The distribution of mosses in other parts of 
the country is not as well known. There are 
checklists of mosses for nearly every U.S. state 
(Pursell 1982), although many were published 
30-40 years ago and are outdated. The 
Southeast has the fewest checklists; the north- 
ern parts of Mississippi, Alabama, and Georgia 
and the southern parts of Arkansas are poorly 
known. 

The Southwest is also one of the least known 
U.S. areas. It has great diversity of habitats 
including mountains, grasslands, and desert 
habitats. Although checklists have been pub- 
lished for all of the states and a flora has been 
published for Utah (Flowers 1973), the mosses 
of Nevada, Arizona, New Mexico, and parts of 
Texas are probably still the least known in the 
country. The recent publication of the moss 
flora of Mexico (Sharp et al. 1994) will consid- 
erably aid workers in this region, but much 
basic floristic work needs to be done. 

Good state checklists exist for the Great 
Plains and the Pacific Northwest, wh*ch has 
checklists for the entire region as well as a 
regional flora (Lawton 1971). The Great Plains 
is reasonably well covered with checklists and 
two regional floras for all of the midcontinent. 
Moss diversity in this region is low, and many 
of the mosses are members of the eastern moss 
flora. But the mosses in this region have not 
been extensively surveyed, and the area contin- 
ues to yield surprises such as Ozobryum 
ogalalense, a new genus (Merrill 1993). 

Alaska has a checklist and work has begun 
on a synoptic flora that will cover the Arctic 



area (Mogensen 1985). Floristically, however, 
the Arctic areas of Alaska are fundamentally 
different from the rest of the United States. A 
portion of flora can be named by using Arctic 
European floras; otherwise, the flora can be 
named only by specialists with access to the 
scattered literature and a good herbarium. 

Liverworts and Hornworts 

No part of the United States can be consid- 
ered well-inventoried for liverworts or horn- 
worts. The eastern half of the country is much 
better known than the West. The preparation of 
Schuster's manual of the liverworts and horn- 
worts of eastern North America (1966-92), 
which resulted in the publication of several 
dozen new species (mostly from the southern 
Appalachians and Florida), has improved our 
knowledge of these plants in the East. Many 
taxonomic problems still need serious study, 
however, and known ranges of distribution are 
still incomplete. 

Our knowledge of the liverwort and horn- 
wort floras in the western half of the country 
has improved recently because of a series of 
local checklists (mostly of national parks and 
similar small floristic units) for the Pacific 
Northwest. For large parts of the northwestern 
United States, however, we still rely on a few 
pioneering studies from 1890 to 1940. 




The liverwort Asterella echinella. 



The most poorly known part of the country 
is undoubtedly the interior Southwest (New 
Mexico, Arizona, and surrounding regions). 
Data from this area are so scanty and inadequate 
that it is difficult to assess the regional liverwort 
and hornwort floras in any meaningful way. 
Recent studies, though, describe several new 
taxa and some range extensions. For instance, 
Mannia fragrans, which seems widespread in 
the mountains of the western United States, was 
not reported from any state west of Colorado 
before 1987. Likewise, Bischler's (1979) revi- 
sion of the xerophytic liverwort genus 
Plagiochasma increased the number of species 
known from the United States from three to five 
(adding two widespread Mexican species from 



200 



Plants — Our Living Resources 



For further information: 

Alan Whittemore 

Missouri Botanical Garden 

PO Box 299 

St. Louis, MO 63166 



Texas and Arizona). Numerous additions to the 
flora can be expected from this part of the coun- 
try if intensive fieldwork is conducted. 

Study of these plants has been handicapped 
by the lack of identification manuals over much 
of the continent. The completion of Schuster's 
manual (1966-92) has improved the situation in 
eastern North America, but there is still almost 
no usable literature from the western half of the 
country. Since the first half of the century, there 
have been no floristic treatments with identifi- 
cation aids of any kind published for any area 
west of the 110th meridian, with the single 
exception of the brief checklist of the liverworts 
and hornworts of Olympic National Park by 
Hong et al. (1989). In the whole of this large 
area, which makes up more than half of the 
country, specimens can only be identified reli- 
ably by specialists with access to rare and often 
outdated literature. Even in the well-studied 
extreme Northeast (i.e.. New England and New 
York), new taxa continue to be found (for exam- 
ple, Pellia megalospora Schust. was not 
described until 1981). Further collection and 
study will surely provide many more range 
extensions. Likewise, the very distinctive 
endemic genus Schofieldia Godfrey was not 
described from western Washington until 1976, 
even though it is without close relatives and is 
rather common in subalpine sites from north- 
western Washington north through the central 
part of the Alaska panhandle. 

References 

Anderson, L.E., H.A. Crum. and W.R. Buck. 1990. List of 
mosses of North America north of Mexico. Bryologist 
93:448-499. 



Bischler, H. 1979. Plagiochasma Lehm. et Lindenb. IV. Les 

taxa americains. Revue Bryologique et Lichenologique 

45:255-334. 
Crum, H. 1983. Mosses of the Great Lakes forest. 3rd ed. 

University of Michigan. Ann Arbor. 417 pp. 
Crum, H., and L.E. Anderson. 1981. Mosses of eastern 

North America. 2 vols. Columbia University Press. 
Flowers, S. 1973. Mosses: Utah and the West. Brigham 

Young University Press. Provo, UT. 567 pp. 
Grout, A.J. 1928-40. Moss flora of North America. 3 vols. 

Self-published, New Fane, VT. 
Hong, W.S., K. Flander, D. Stockton, and D. Trexler. 1989. 

An annotated checklist of the liverworts and hornworts of 

Olympic National Park, Washington. Evansia 6:33-52. 
Lawton. E. 1971. Moss flora of the Pacific Northwest. 

Hattori Botanical Laboratory, Nichinan. Japan. 362 pp. 
Merrill. G.S. 1993. Ozobryum ogalalense (Pottiaceae), a 

new genus and species from the American Great Plains. 

Novon 2:255-258. 
Mogensen. G.S. 1985. Illustrated moss flora of Arctic North 

America and Greenland. Bioscience 17:1-8. 
Pursell. R.A. 1982. A synopsis of moss floristics in the east- 
ern United States. Beihefte zur Nova Hedwigia 

71:451-454. 
Redfeam, P.L., Jr. 1983. Mosses of the Interior Highlands of 

North America. Revision Missouri Botanical Garden. St. 

Louis. 104 pp. 
Schofield, W.B. 1980. Phytogeography of the mosses of 

North America (north of Mexico). Pages 131-170 in R.J. 

Taylor and A.E. Leviton, eds. The Mosses of North 

America Symposium. Pacific Division. American 

Association for the Advancement of Science, San 

Francisco. 
Schuster. R.M. 1966-92. The Hepaticae and Anthocerotae 

of North America, east of the hundredth meridian. Vols. 

1 -4. Columbia University Press. New York. Vols. 5-6, 

The Field Museum. Chicago. 
Schuster, R.M. 1984. Phytogeography of the Bryophyta. 

Pages 463-626 in R.M. Schuster, ed. New manual of bry- 
ology. Vol. 1 . Hattori Botanical Laboratory. Nichinan. 

Japan. 
Sharp, A.J., H. Crum, and P.M. Eckel, eds. 1994. The moss 

flora of Mexico. Memoirs of the New York Botanical 

Garden 69. 1113 pp. 



Vascular 
Plants of the 
United States 

by 

Nancy Morin 

Missouri Botanical Garden 



Information on the plants of the United States 
can be found in floras, monographs, and var- 
ious lists and reports. Herbarium collections 
provide an invaluable record of past and current 
distributions of U.S. plants and form the basis 
for published accounts of the plants such as flo- 
ras and checklists. Properly understanding and 
managing U.S. plant resources depend on hav- 
ing physical samples that document the charac- 
teristics and distributions of plants and on the 
scientific studies of the relationships, character- 
istics, distributions, and physical requirements 
of the plants. Although such documentation 
exists for some areas of the country, many areas 
are still poorly known, and authoritative refer- 
ences are still lacking for some. 

About 1 7,000 species of vascular plants (i.e., 
flowering plants, gymnosperms, and ferns) 
occur in the contiguous United States and 
Alaska (Flora of North America Editorial 
Committee 1993); Hawaii is home to more than 
1 ,800 species of flowering plants (Wagner et al. 



1990), few of which are found on the North 
American mainland. Trees have been most com- 
pletely documented, followed by shrubs and 
showy herbaceous plants. Known distributions 
of rare plants are generally available in comput- 
erized data bases, often maintained by state 
Natural Heritage Programs. Nationwide data- 
base files for rare plants are maintained by The 
Nature Conservancy. 

Non-natives and inconspicuous natives are 
often overlooked by plant collectors and thus 
are less well documented. In much of the conti- 
nent, and especially in highly populated areas, 
however, the native flora has been altered so 
completely by humans that "native" or "natur- 
al" vegetation is almost beyond conception. 
Because of this, the historical portrait of plant 
distribution that can be drawn based on herbar- 
ium specimens is extremely valuable to under- 
stand the pre-Columbian composition of our 
flora and the relation of plants to their environ- 
ment. Modern collecting still brings many new 



Our Living Resources — Plains 



201 



species to light. Between 1975 and 1989, for 
example, 725 new taxa of vascular plants were 
reported from the conterminous United States 
alone (Hartman 1990). 

The following discussions indicate what 
published plant information and data bases exist 
and describe the level of current and historical 
plant collecting in the United States. 

Major Plant Groups 

Few families or genera in the United States 
have been studied comprehensively throughout 
their range during the past 50 years, and until 
now there has been no source that brings togeth- 
er the best existing knowledge of U.S. plant 
taxa. To provide such a resource, plant taxono- 
mists from the United States and Canada have 
established the Flora of North America project. 
Scientific information on the names, relation- 
ships, characteristics, and distributions of all 
plants that grow outside of cultivation in North 
America north of Mexico will be published in 
14 volumes and in an online data base over the 
next 8 years. To date, two volumes have been 
published (Flora of North America Editorial 
Committee 1993). As information is synthe- 
sized and published, research needs can be 
evaluated. Checklists of North American plants 
are currently available (Soil Conservation 
Service 1982; Kartesz 1994), and the Soil 
Conservation Service maintains a data base of 
Plant List of Attributes, Nomenclature, 
Taxonomy, and Symbols (PLANTS) for North 
America. 

Pteridophytes 

About 500 species of ferns and fern allies 
are found in the United States, excluding 
Hawaii where about 200 occur. The most recent 
treatment of ferns for North America is in 
Volume 2 of Flora of North America (Flora of 
North America Editorial Committee 1993). 
Recent studies involving DNA analysis, 
isozyme work, and modern statistical analyses 
have significantly improved our understanding 
of genetic relationships among groups of ferns 
(Wagner and Smith 1993). Fern groups in the 
dry areas of the Southwest especially need 
study. 

Gymnosperms 

Gymnosperms, with 118 species (none 
native to Hawaii), include the economically 
important conifers. Tremendous research has 
been done on conifers, including detailed popu- 
lation studies of individual species. The most 
recent treatment of gymnosperms for North 
America is Volume 2 of Flora of North America 
(Flora of North America Editorial Committee 



1993). The Atlas of United States Trees (Little 
1971), although somewhat outdated, is still the 
best source for precise distributional informa- 
tion for conifers. 

Angiosperms 

Most vascular plant species in the United 
States are angiosperms, those plants bearing 
what are commonly recognized as flowers. The 
large sunflower family has been intensively 
studied over the past several decades, although 
work on this family is hampered by its com- 
plexity and the difficulty of identifying individ- 
ual plants. In addition, more extensive survey- 
ing of the Southwest is needed to understand the 
family. An account of Asteraceae for the south- 
eastern United States was published in The 
Vascular Flora of the Southeastern United 
States (Radford et al. 1980); Great Basin 
species are treated in Volume 5 of the 
Intermountain Flora (Cronquist et al. 1972-94), 
and Asteraceae will appear as the final pub- 
lished volume of Flora of North America. 

The grass family is the most agriculturally 
important family in the United States, both for 
its forage value and as a source for crop and 
rangeland weeds. Researchers coordinated by 
Utah State University are revising the Manual 
of the Grasses of the United States (Hitchcock 
and Chase 1950). 

Much work on the complex legume family 
has been done by researchers in the U.S. 
Department of Agriculture. Genera such as 
Astragalus, with more than 325 species, still 
require tremendous work to understand; it is 
extremely difficult to identify individual 
species. An international program to develop a 
checklist of species in this family, with distrib- 
ution, growth habit, and economic information, 
is being carried out by the International Legume 
Data Information System (ILDIS); the Missouri 
Botanical Garden is the center for North 
American information for this project. 

The sedge family includes ecologically 
important species, especially in wetlands where 
sedges dominate. Although sedges are being 
intensively studied, individual species can be 
difficult to identify; Carex alone contains more 
than 400 species. Cyperaceae specialists have 
been collaborating on common solutions to tax- 
onomic problems in this group; volume 1 1 of 
Flora of North America will synthesize the best 
information available on the family. 

Regional Floras 

Hawaii 

The Manual of the Flowering Plants of 
Hawaii (Wagner et al. 1990) gives excellent 
coverage for flowering plants. Two fern floras 




Scleria cilata, a member of the 
sedge family, Cyperaceae. 




The fern Cyrtomiumfalcatum. 



202 



Plants — Our Living Resources 




Bouteloua gracilis-, a member of 
the grass family, Poaceae 
(Gramineae). 




The fern Polxsiichum lonchitis. 




The fern Pityrogramma trifoliata. 



are in progress. In addition, the Bishop 
Museum, the National Tropical Botanical 
Garden, and the National Museum of Natural 
History, Smithsonian Institution, are collabora- 
tively creating a data base for their flowering 
plant specimens from Hawaii, a project to be 
completed by 1996. The Bishop Museum has a 
checklist data base of native and cultivated 
plants in Hawaii, but additional collecting is 
needed to document native plants, particularly 
on Molokai and Kauai. Collecting is needed 
throughout the islands to document the intro- 
duction and spread of alien plants. Scientists at 
the National Tropical Botanical Garden have 
discovered 20 new taxa from Kauai alone since 
1990, and some 200 species of naturalized 
plants have been discovered in Hawaii in the 
past 5 years. 

Alaska 

Alaska has such a huge area of wilderness 
that basic botanical exploration is essential; 
Flora of Alaska and Neighboring Territories 
(Hulten 1968) is a useful work. In addition, a 
data base for Alaskan plants is maintained at the 
University of Alaska Museum in Fairbanks. 
Rare plants are tracked by the University of 
Alaska, the Alaska Natural Heritage Program, 
and the Alaska Rare Plant Working Group (an 
ad hoc group of botanists from state and feder- 
al agencies, the university, and nongovernmen- 
tal organizations). 

The West 

The western region of the continental United 
States is probably the least known. Some areas 
(mostly near cities with universities, along high- 
ways, and popular camping sites) are relatively 
well known, but in less populated areas not near 
paved roads, much remains to be explored. 

Three excellent floras treat the plants of the 
west coast: Vascular Plants of the Pacific 
Northwest (Hitchcock et al. 1955-69); 
Intermountain Flora (Cronquist et al. 1972-94); 
and The Jepson Manual: Higher Plants of 
California (Hickman 1993). State floras for 
Oregon (Peck 1961), Washington (Piper 1906), 
and Idaho (Davis 1952) are out of date and need 
to be revised. A revised checklist for Oregon is 
in preparation (A. Liston, Oregon State 
University, personal communication). 
Specimen data bases are being developed for 
California, Oregon, and Idaho. California 
herbaria have developed a model project 
(Specimen Management System for California 
Herbaria, SMASCH) to computerize data from 
all their California specimens. Specimens 
(including lichens and fungi) in Oregon 
herbaria are being put into a data base. 

The Klamath-Siskiyou area of California 
and Oregon, mid-elevation Sierra, and the inter- 



mountain portion of California are the most 
poorly known regions. For instance, a showy 
new species of the genus Neviusia, the 
snow-wreath, previously known from only one 
species in the southeastern United States, was 
recently discovered in 1992 in an accessible 
area of northern California (Shevock et al. 
1992). In addition, the rich flora of southwest- 
ern Oregon is poorly represented in herbaria, as 
are several counties in north-central Oregon (A. 
Liston, personal communication). 

Intermountain Area 

The number of collections from the 
Intermountain region has doubled in the past 20 
years. The Intermountain Flora (Cronquist et al. 
1972-94), which treats Utah, most of Nevada, 
southeastern Oregon, southern Idaho, and east- 
ern California, is comprehensive; five of seven 
volumes have been published. An unpublished 
flora of Nevada exists (Kartesz 1987). 

Nevada is one of the most poorly explored 
and documented states. Recent collectors have 
concentrated activity in the Great Basin moun- 
tains of Nevada and the Colorado Plateau of 
Utah. Even in areas seemingly well-collected, 
such as Zion National Park in southwestern 
Utah, a number of new species have been dis- 
covered and described since 1975 (Hartman 
1990). A Utah Flora (Welsh 1993) and Atlas of 
the Vascular Plants of Utah (Albee et al. 1988) 
are modern and thorough treatments. 

The Southwest 

Although many local floras have been pre- 
pared for the Rocky Mountain areas, few have 
been published. Data bases on distribution of 
species are also being developed for individual 
states at the University of New Mexico, Utah 
State University, Colorado State University, the 
University of Colorado, and the University of 
Wyoming. A computerized checklist is being 
prepared for New Mexico at New Mexico State 
University in Las Cruces. Most of Arizona and 
New Mexico have been poorly collected, but 
these two states are thought to be the floristical- 
ly richest areas in the United States, and new 
and surprising species are being discovered 
yearly. References for New Mexico (Martin and 
Hutchins 1980-81) are outdated or poor. In New 
Mexico, for instance, even frequently visited 
sites like the Chiricahuas still reveal treasures, 
such as Apacheria, a new genus discovered in 
1973 (Mason 1975). 

Northern Arizona University maintains a 
data base on conifers and grasses of the state; 
the remainder of its Arizona holdings are also 
being entered. In addition, the University of 
Arizona has a major data-base project. Areas 
needing more collection in Arizona include 
north of the Colorado River and parts of the 



Our Living Resources — Plants 



203 



Colorado Plateau (L.R. Landrum, Arizona State 
University, and T.J. Ayers, Northern Arizona 
University, personal communication). 

Although much of Colorado is also poorly 
known, all of Wyoming will have been surveyed 
by 1998, with recent collection data fully com- 
puterized (R. Hartman, University of Wyoming, 
personal communication). 

The Great Plains 

The Flora of the Great Plains (Great Plains 
Flora Association 1986) and its associated Atlas 
of the Flora of the Great Plains (Great Plains 
Flora Association 1977) are the result of careful 
study of the region in the 1960's and 1970's. 
The University of Kansas herbarium contains 
specimens representative of the entire flora; 
these specimens have been recently annotated 
by experts. This herbarium, in combination with 
those at the University of Nebraska, Kansas 
State University in Manhattan, North Dakota 
State University in Fargo, and the University of 
Minnesota (which has specimen data online), 
probably has fully covered this region and has 
current, active collecting programs. These 
herbaria are collaborating to develop a Central 
United States Plant Inventory Database (CUS- 
PID). South Dakota and the eastern half of 
Montana have been undercollected. 

Great Lakes 

Many poorly known and interesting species 
are restricted to the Great Lakes region, and 
other typically more northern species occur here 
(The Nature Conservancy 1994). Recent floras 
are available or are being prepared for Illinois, 
Michigan, Minnesota, and Ohio. The floras of 
Indiana and Wisconsin need to be updated. 
Information from specimens treated in recent 
volumes of the Michigan Flora (Voss 1972) is 
being entered into a data base, and the Kent 
State University herbarium is computerizing its 
collection. 

The Eastern Forest 

The region covered by the eastern forest has 
been settled longer than any other area in the 
United States. Habitats here have undergone 
tremendous alteration and many introduced 
species now dominate the landscape. These 
plants should be regularly inventoried to docu- 
ment the occurrence and spread of alien species 
and to monitor the effects of environmental 
change. For instance, in 1950, 20% of the species 
in the northeastern United States were non-native 
(Fernald 1950); in 1986, 36% of the flora of New 
York was non-native (Mitchell 1986). 

Regional, statewide, and local floristic stud- 
ies and publications are traditional in the 
Northeast, but the older work is sometimes tax- 



onomically and nomenclaturally outdated, and 
many areas remain inadequately inventoried. 
Two standard references for the vascular plants 
of the Northeast are Gray's Manual of Botany 
(Fernald 1950) and the recently revised Manual 
of Vascular Plants of Northeastern United 
States and Adjacent Canada (Gleason and 
Cronquist 1991). Seymour's (1982) The Flora 
of New England is also useful. 

Botanists in Maine, Vermont, New 
Hampshire, Connecticut, and Massachusetts are 
updating checklists or older floras or preparing 
new ones. In New York, an active collaborative 
flora project has produced 10 illustrated install- 
ments, plus a checklist (Mitchell 1986) and an 
atlas of county records (New York Flora 
Association 1990). For Pennsylvania, Rhoads 
and Klein's (1993) recent atlas is available. 

A book on the aquatic plants of northeastern 
North America is soon to be published (G.E. 
Crow, University of New Hampshire, and C.B. 
Hellquist, North Adams State College, 
Massachusetts, personal communication). In 
addition, the Association of Northeastern 
Herbaria, organized in 1991, is coordinating the 
preparation of specimen-based electronic data 
bases and the sharing of data. Specimen data 
from herbaria at the University of 
Massachusetts (Amherst), the Buffalo Museum 
of Science, the New York State Museum, and 
the University of Maine are partly or complete- 
ly stored electronically. A large computer-stored 
data base also exists for Pennsylvania plants. 

The South 

The Manual of the Vascular Plants of Texas 
(Correll and Johnston 1970) is being updated. 
A number of regional floras and checklists have 
been published within the last two decades, but 
there are no regional floras for the Rolling 
Plains or the Trans-Pecos areas. Specimen 
records at the University of Texas at El Paso 
have been computerized, and type specimens at 
the University of Texas at Austin are computer- 
ized and online. 

In general, local floras, checklists, and 
atlases are more commonly available for south- 
eastern states than are complete state floras. In 
the southeast, Alabama, Arkansas, and 
Mississippi are the most poorly known, and 
northern Florida, Georgia, northwestern 
Louisiana, and eastern Oklahoma need consid- 
erably more study. In Alabama, in particular, the 
poorly collected areas are the Coastal Plain 
north of Mobile and Baldwin counties, north to 
the Cumberland Plateau. For overviews, see The 
Vascular Flora of the Southeastern United 
States (Radford et al. 1 980), of which two of the 
five projected volumes have been published. A 
Generic Flora of the Southeastern United States 
(Wood and Miller 1958-90), which includes 




Fabaceae (Leguminosae). Baptisa 
australis, a member of the legume 
family. 




The fern Acrostichum danaeifolium. 




The fern Pityrogramma vittata. 



204 



Plants — Our Living Resources 




Picea sitchensis, a member of the 
pine family. Pinaceae. 




The fem Phanerophlebia auriculata. 




The fern Ctenitis sloanei. 




The fern Olenitis submareinalii 



keys to genera and discussions about species 
and their distributions in the Southeast, is about 
80% finished. The latest complete flora is 
Small's (1933) manual. The Manual of the 
Vascular Flora of the Carolinas (Radford et al. 
1968) is a standard and reliable reference. A 
flora of Florida and atlas of the vascular plants 
of Florida are under way (R.P. Wunderlin, 
University of South Florida, personal communi- 
cation). In addition, extensive computerized 
data bases on distribution, literature, and 
nomenclature of Florida plants exist at the 
University of South Florida. 

In Florida, the specimen coverage is incom- 
plete in sparsely populated areas (e.g., several 
eastern Panhandle counties and northeastern 
counties). At least one new species per year is 
described from Florida and these mostly have 
limited distributions and are in imperiled habi- 
tats. 

Herbaria in the southeastern United States 
have formed a consortium (Southeastern 
Regional Floral Information System) to com- 
puterize specimen records in all southeastern 
herbaria. The information from this project is 
available online at the University of Alabama. 

Invasion of weedy species is one of the most 
serious threats to native vegetation in the south- 
eastern United States. Much better documenta- 
tion of the occurrence and spread of these 
species is needed to control these invaders. 

Collecting and Monitoring 

Active collecting programs document and 
monitor changes in distribution of native and 
introduced species. Introduced plants and plant 
migrations often affect the distribution and 
health of native plants. At present, it can take as 
long as 20 years after an introduction to collect 
and record the species in the literature. 

Long-term care of these national collections 
is vital; many regional herbaria no longer have 
curatorial support, and some have been or are in 
danger of being abandoned by their institutions, 
which will limit resources and information for 
studies. 

References 

Albee. B., L.M. Shultz, and S. Goodrich. 1988. Atlas of the 
vascular plants of Utah. Utah Museum of Natural 
History, Salt Lake City. 670 pp. 

Correll. D.S.. and M.C. Johnston. 1970. Manual of the vas- 
cular plants of Texas. Texas Research Foundation. 
Renner. 188 pp. 

Cronquist, A.. A.H. Holmgren. N.H. Holmgren. J.L. Reveal, 
P.K. Holmgren, and R.C. Barneby. 1972-94+. 
Intermountain flora: vascular plants of the Intermountain 
West. U.S.A. 5+ vols. Hafner Publishing Co.. New York. 
(Vol. 5-Composite. Columbia University Press.) 

Davis, R. 1952. Flora of Idaho. W.C. Brown. Dubuque, I A. 
828 pp. 

Fernald, M.L. 1950. Gray's manual of botany. 8th ed. 
American Book Co.. New York. 



Flora of North America Editorial Committee. 1993. Flora of 
North America: north of Mexico. Vols. 1 and 2. Oxford 
University Press. New York. 

Gleason. H.A., and A. Cronquist. 1991. Manual of vascular 
plants of northeastern United States and adjacent 
Canada. 2nd ed. New York Botanical Garden. New York. 
910 pp. 

Great Plains Flora Association. 1977. Atlas of the flora of 
the Great Plains. University Press of Kansas. Lawrence. 
600 pp. 

Great Plains Flora Association. 1986. Flora of the Great 
Plains. University Press of Kansas, Lawrence. 1.392 pp. 

Hartman. R.L. 1990. New taxa described from the conter- 
minous United States. 1975-1989. Unpublished report. 

Hickman, J., ed. 1993. The Jepson manual: higher plants of 
California. University of California, Berkeley. 1.400 pp. 

Hitchcock, A.S., and A. Chase. 1950. Manual of the grasses 
of the United States. 2 vols. Dover Publications. New 
York. 

Hitchcock. C.L.. A. Cronquist. M. Ownbey, and J.W. 
Thompson. 1955-69. Vascular plants of the Pacific 
Northwest. 5 vols. University of Washington Press. 
Seattle. 

Hulten. E. 1968. Flora of Alaska and neighboring territo- 
ries: a manual of the vascular plants. Stanford University 
Press, Stanford. CA. 1 .008 pp. 

Kartesz, J.T. 1987. A flora of Nevada. Ph.D. dissertation. 
University of Nevada. Reno. 

Kartesz, J.T. 1994. A synonymized checklist of the vascular 
flora of the United States. Canada, and Greenland. 2 vols. 
Timber Press, Portland. OR. 

Little, E.L.. Jr. 1971. Atlas of United States trees. Vol. 1. 
Conifers and important hardwoods. U.S.D.A. 
Miscellaneous Publ. 1 146. Washington. DC. 

Martin. W.C, and C.R. Hutchins. 1980-81. A flora of New 
Mexico. 2 vols. J. Cramer. Vaduz. NM. 

Mason. C.T., Jr. 1975. Apacheria chiricahuensis: a new 
genus and species from Arizona. Madrono 23:105-108. 

Mitchell. R.S. 1986. A checklist of New York State plants. 
New York State Museum Bull. 458. 272 pp. 

New York Flora Association. 1990. Preliminary vouchered 
atlas of New York State flora. New York State Museum 
Institute. Albany. 496 pp. 

Peck. M.E. 1961. A manual of the higher plants of Oregon. 
Binfords & Mort. Portland. OR. 936 pp. 

Piper, C.V. 1906. Flora of the state of Washington. 
Contributions from the United States National 
Herbarium 11:1-637. 

Radford. A.E., H.E. Ahles, and C.R. Bell. 1968. Manual of 
the vascular flora of the Carolinas. University of North 
Carolina Press. Chapel Hill. 1.183 pp. 

Radford, A.E.. J.W. Hardin. J.R. Massey. E.L. Core, and 
L.S. Radford, eds. 1980. Vascular flora of the southeast- 
ern United States. 3 vols. University of North Carolina 
Press. Chapel Hill. 

Rhoads. A.F.. and W.M. Klein. Jr. 1993. The vascular flora 
of Pennsylvania: annotated checklist and atlas. American 
Philosophical Society. Philadelphia. 636 pp. 

Seymour. F.C. 1982. The flora of New England: a manual 
for the identification of all vascular plants including ferns 
and fern allies growing without cultivation in New 
England. Phytologia Memoirs 5. Moldenke. Plainfield. 
NJ. 611 pp. 

Shevock. J.R.. B. Enter, and D.W. Taylor. 1992. Neviusia 
cUftonii (Rosaceae: Kerrieae). an intriguing new relict 
species from California. Novon 2:285-289. 

Small, J.K. 1933. Manual of the southeastern flora. 
University of North Carolina Press. Chapel Hill. 1.554 pp. 

Soil Conservation Service. 1982. National list of scientific 
plant names. 2 vols. U.S. Department of Agriculture. 
Washington. DC. 

The Nature Conservancy. 1994. The conservation of biolog- 
ical diversity in the Great Lakes ecosystem: issues and 
opportunities. (Unpublished report.) 



Our Living Resources — Plums 



205 



Voss, E.G. 1972. Michigan flora: a guide to the identifica- 
tion and occurrence of the native and naturalized seed 
plants of the state. 2 vols. Cranbrook Institute of Science, 
Bloomfield Hills, MI. 

Wagner, W.L., D.R. Herbst, and S.H. Sohmer. 1990. Manual 
of the flowering plants of Hawaii. 2 vols. University of 
Hawaii Press and Bishop Museum Press, Honolulu. 



Wagner, W.H., Jr., and A.R. Smith. 1993. Pteridophytes. 
Flora of North America. Vol. 1:247-266. Oxford 
University Press. New York. 

Welsh, S. L. 1993. A Utah flora. Brigham Young University, 
Provo, UT. 

Wood, C.E., Jr., and N. G. Miller, eds. 1958-90. A generic- 
flora of the southeastern United States. Journal of the 
Arnold Arboretum Supplementary Series, 199+. 



For further information: 

Nancy Morin 

Missouri Botanical Garden 

PO Box 299 

St. Louis, MO 63166 



Many of the best-known cases of cata- 
strophic decline in trees are linked to 
introduced pathogens that circumvent the 
natural defenses of their adopted host, leav- 
ing it vulnerable to attack. Notable examples 
of such declines include Dutch elm disease 
and the chestnut blight. Similarly, numerous 
studies have linked environmental degrada- 
tion (e.g., acid rain, ozone depletion, and 
global warming) to altered interactions 
among species. In the case of plants and 
their pathogens, environmental degradation 
may result in increased disease susceptibili- 
ty and mortality as is true for the general for- 
est declines in Europe and the widespread 
decline of red spruce (Picea rubens) in the 
northeastern United States. Identifying the 
specific mechanisms for increased mortality 
in nonspecific tree declines is often very dif- 
ficult, and debate ensues as to which sources 
of mortality are primary disease agents and 
which are merely opportunistic. 

Both introduced pathogens and altered 
environmental conditions have been hypoth- 
esized as contributing to the decline of 
Torreya taxifolia, a narrowly restricted 
endemic conifer. The range of the Florida 
torreya spans an area of less than 400 km 2 
(154 mi 2 ) along the Apalachicola River in 
northern Florida and adjacent Georgia. In 
the 1950's this mid-sized tree species was 
struck by a catastrophic decline that has left 
it on the verge of extinction in the wild. High 
mortality is reducing the population by an 
estimated 5% per year. Formerly a common 
tree within its range, there are fewer than 
1,500 trees left in the wild. 

The average height of a Florida torreya is 
currently less than 1 m (3.3 ft). The average 
age of the oldest stem on trees is less than 15 
years. While a handful of trees produces 
pollen, there have been no sexually mature 



Environmental Change 
and the Florida Torreya 



Mark W. Schwartz 
University of California-Davis 

Sharon M. Hermann 
Tall Timbers Research Station 



females observed in the wild for at least 15 
years. Symptoms of disease include needle 
spots, needle necrosis, and stem cankers. 
Primary stem mortality has reduced the aver- 
age height of trees by 10 cm (4 in) during the 
past 3 years. Thus, the Florida torreya has 
shown no sign of recovery or stabilization 
during the 35 years subsequent to the onset 
of the species' decline. If current patterns 
persist, the Florida torreya is destined for 
extinction in the wild. 

The search for a cause for the decline of 
the Florida torreya began in the 1960's when 
a team of pathologists studying the case 
could find no introduced fungal pathogens. 
Pathologists studying the problem during the 
1990's have shown that (1) there does not 
appear to be any viral or bacterial pathogens 
associated with T. taxifolia; (2) a very com- 
mon native fungal endophyte (Pestalotia 
nutans), often pathogenic in other plants, 
does not appear virulent on T. taxifolia; and 
(3) the less common Scytalidium sp., not 
typically noted for its pathogenicity, pro- 
duces pathogenic symptoms on T. taxifolia 
and was likely introduced to the region dur- 
ing the late 1950's, when slash pine planta- 
tions were planted from nursery stock. 
Finally, growth experiments have suggested 
that environmental stress triggers episodes 
of mortality in the trees. Greenhouse experi- 
ments on Florida torreya trees derived from 



cuttings also suggest the likelihood that 
structural changes in the slope forests along 
the Apalachicola that have resulted in lower 
light levels have also stressed wild popula- 
tions of Florida torreya. 

The current hypothesis is that the decline 
of Florida torreya is a result of facultative 
(see glossary) pathogens attacking trees 
under conditions of increased environmental 
stress. Several potential stress factors, 
including fire suppression, climatic changes 
such as temperature extremes and drought, 
and altered hydrologic regimes in ravine 
forests and resultant changes in nutrient flow 
have also been hypothesized as contributing 
to the species' decline. 

Despite extensive research to find a link 
between disease agents and environmental 
stress, the mechanisms for forest decline 
remain rather speculative. Torreya taxifolia 
has such a narrow distribution that a decline 
in the populations in the Apalachicola basin 
has brought the species to near extinction. 
With the increasing magnitude of abiotic 
environmental changes, we may expect 
more cases that are similar to the decline of 
T. taxifolia. Unfortunately, the lack of iden- 
tification of specific disease agents and spe- 
cific mechanisms has hindered action to cor- 
rect potential problems that cause forest 
declines. Given the difficulty in delineating 
mechanisms for declines, we typically can- 
not ascertain exact mechanisms until it may 
be too late. Waiting to be absolutely certain 
of the triggers for particular forest declines 
before corrective action is taken is likely to 
be a costly strategy. 

For further information: 

Mark W. Schwartz 
Center for Population Biology 
University of California-Davis 

Davis, CA 95616 



Most of the familiar flora of the American 
landscape, such as trees, shrubs, herbs, 
vines, grasses, and ferns, are known as vascular 
plants. These plants have systems for transport- 
ing water and photosynthetic products and are 
differentiated into stems, leaves, and roots. 
Nonvascular plants — the algae, fungi, and 
mosses and lichens — are considered in other 
articles in this volume. Except in Arctic and 
alpine areas, vascular plants dominate nearly all 



of North America's natural plant communities. 
About 17,000 species of vascular plants are 
native to one or more of the 50 U.S. states, 
along with several thousand additional native 
subspecies, varieties, and named natural hybrids 
(Kartesz 1994). 

Human activities have expanded the geo- 
graphical distributions of many plant species, 
particularly farm crops, timber trees, garden 
plants, and weeds. When a non-native plant 



Native 

Vascular 

Plants 



206 



Plants — Our Living Resources 



by 

Larry E. Morse 

The Nature Conservancy 

John T. Kartesz 

North Carolina Botanical 

Garden 

Lynn S. Kutner 
The Nature Conservancy 




No. of native plants 
■ >4,000 
H 3,000-3,999 

□ 2,400-2,999 

□ 2,000 - 2,399 

□ 1,600-1,999 

□ <1 ,600 

Fig. 1. The number of native vas- 
cular plant species in each state. 



u> 6 



C 5 



o. 3 



2 2 



6 




GH/GX G1 G2 G3 G4 G5 

Fig. 2. The number of native vas- 
cular plant species in the United 
States in each global rank. GH/GX 
means species is potentially 
extinct; Gl to G5 rank the species 
hum rarest (Gl ) to most common 
(G5). 



species is found growing outside cultivation, it 
is considered an exotic species in that area. 
About 5,000 exotic species are known outside 
cultivation in the United States. While many 
exotic plant species are desirable in some con- 
texts (such as horticulture), hundreds of inva- 
sive non-natives have become major manage- 
ment problems when established in places val- 
ued as natural areas (McKnight 1991; U.S. 
Congress 1993). A few particularly troublesome 
non-natives are regulated under specific federal 
or state laws as noxious weeds. 

Geographic Distribution 

Western and southern states have the largest 
numbers of native vascular plant species in the 
country. (Fig. 1, revised from Kartesz 1992). 
California, with more than 5,000 native vascu- 
lar plant species, has almost one-third of the 
total number for the entire United States. Texas, 
with about 4,500 native species, ranks second. 
Arizona, Florida, Georgia, New Mexico, and 
Oregon all have over 3,000 native species. 

Hawaii, as a remote oceanic island archipel- 
ago, has relatively few native species (Carlquist 
1970), but nearly all (89%) of the native 
Hawaiian flowering (angiosperm) species are 
endemic to that region (Wagner et al. 1990). A 
small number of vascular plants, including a 
species of lycopod (Huperzia haleakalae), are 
native to both Hawaii and the North American 
mainland. 

In every state, hundreds of plant species are 
established as exotics. States with coastal areas, 
major agricultural regions, and large cities gen- 
erally have the highest numbers of non-native 
plants. A modest number of native U.S. species, 
such as the northern catalpa (Catalpa speciosa), 
have also spread from cultivation beyond their 
native ranges. Some familiar mainland species, 
like a wild blackberry (Rubus argutus) and a 
grass known as broomsedge (Andropogon vir- 
ginicus), have become problem weeds in 
Hawaii (Smith 1989). 

Rare Species 

As of February 1994, 403 native U.S. 
species, subspecies, or varieties of vascular 
plants and one nonvascular plant have been for- 
mally protected under the provisions of the U.S. 
Endangered Species Act of 1973 (USFWS 
1994). Nearly half the 822 native U.S. federally 
listed species are plants. The U.S. Fish and 
Wildlife Service considers an additional 1,953 
kinds of plants as candidates for such listing 
(Federal Register 1993). 

The first U.S. national lists of rare plants 
depended largely on nominations from special- 



ists already familiar with various rare species 
and omitted many potential candidates. Many 
state-level rare plant lists were also developed 
in the 1970's; these generally addressed species 
considered rare in a particular area regardless of 
abundance elsewhere. 

The Nature Conservancy and the network of 
Natural Heritage Programs use a consistent 
methodology to inventory natural diversity and 
to assess rarity and endangerment for all cur- 
rently recognized species of vascular plants in 
North America, Hawaii, and portions of Latin 
America (Jenkins 1985). By using a five-level 
scale from 1 (rarest and most vulnerable — typi- 
cally five or fewer existing occurrences) to 5 
(demonstrably widespread, abundant, and 
secure), a global or rangewide rank (Gl to G5) 
is determined for each species. With the use of 
the same five-level scale, conservation priority 
ranks are assigned for national (Nl to N5) and 
subnational or state (SI to S5) status. Ranks are 
used conservatively throughout the Natural 
Heritage Network and are assigned after careful 
review of a species' status. Additional ranks are 
used to indicate species that occurred historical- 
ly within a jurisdiction, but which are not 
presently known. A species is presumed extinct 
if efforts to relocate it are unsuccessful, if no 
suitable habitat remains, or if the loss has been 
well documented. Species are considered "his- 
toric" (possibly extinct) if there is reliable evi- 
dence from biological surveys that the species 
occurred within the past few centuries in a given 
area (Snyder 1993). 

The Natural Heritage Network has docu- 
mented the status of thousands of rare species. 
At the same time, plant surveys have shown that 
a comparable number of plants are substantially 
more common than previously believed. 
Species status information from all 50 U.S. 
State Natural Heritage Programs is combined 
with national and rangewide data in the Natural 
Heritage Network's Central Scientific 
Databases maintained by The Nature 
Conservancy. The inventories and data bases of 
the Natural Heritage Network continuously 
gather, organize, and revise information on 
species rarity and distribution as it becomes 
available. 

The number of species in the United States 
in each global rank is presented in Fig. 2. For 
example, more than 4,850 species (about 28%) 
of the native U.S. vascular plants are considered 
globally rare (ranked Gl, G2, or G3) by The 
Nature Conservancy and the Natural Heritage 
Network. Of these, about 960 species are 
ranked Gl and occur at fewer than five sites 
globally or are comparably imperiled. 

Globally rare native species of vascular 
plants are concentrated in the western and 



Our Living Resources — Plants 



207 



southern states (Fig. 3), with greatest propor- 
tions in Arizona, California, Florida, Georgia, 
Hawaii, Nevada, New Mexico, Texas, and Utah. 
In addition to these globally rare species, 
about 4,500 other species of widespread or 
more common vascular plants (ranked G4 or 
G5) are being actively inventoried in at least 
one state where they are rare. 

Loss of Species 

The patterns and causes of plant species' 
losses are often important components of state- 
level conservation studies. The loss, or suspect- 
ed loss, of a species from a portion of the land- 
scape is referred to as "extirpation." 

A recent study (Kutner and Morse, unpub- 
lished report) of the losses of U.S. native vas- 
cular plants revealed that about 1,772 (9.8%) of 
these species have been lost from at least one 
state. Of these species, 438 (25%) may be lost 
from the floras of two or more states. The pro- 
portion of species potentially extirpated from 
each state varies dramatically across the nation 
(Fig. 4), with the largest losses reported from 
northeastern states and from Hawaii. Delaware 
has experienced the proportionately highest 
loss from its flora, with more than 15% of its 
species potentially extirpated. Many of the 
northeastern and mid-Atlantic states have lost 
more than 5% of their native vascular plants. 
This region of the United States has experi- 
enced hundreds of years of human development 
and includes many of the most densely populat- 
ed and intensely developed states. Many plants 
that have been lost from these states may now 
be similarly threatened in portions of their 
remaining ranges. 

About 28% of the native flora is considered 
globally rare (ranked Gl, G2, or G3) by the 
Natural Heritage Network, but only 12% of the 
potentially extirpated species are globally rare. 
Most potentially extirpated species have been 
lost from one or two states and are currently 
globally common (ranked G4 or G5). In the 
United States, 110 of these globally common 
species have been lost from three or more 
states, and more than 35 species have been lost 
from four or more states. Of the most common 
species (global rank G5), about 285 have been 
lost from two or more states. Common species 
that have been lost from many states may not be 
as secure from imperilment as previously 
believed. Additionally, the effect of species' 
losses on other plants and animals in a commu- 
nity is often unknown. Rangewide analyses 
could indicate species that would benefit from 
further research and a better understanding of 
potential threats, thus helping prevent subse- 
quent losses. 



Many species that are endangered, threat- 
ened, or formal candidates for federal protec- 
tion have also lost parts of their ranges. Nearly 
6% of listed and proposed endangered species 
and 20% of listed and proposed threatened 
species are reported extirpated from at least one 
state. About 16% of the category 1 candidate 
species (top candidates for listing as endan- 
gered or threatened) and almost 1 1% of the cat- 
egory 2 candidate species (possibly qualifying 
for threatened or endangered status, but more 
information is needed) have been similarly 
affected. 

Some currently rare species had widespread 
historical distributions. For example, American 
chaffseed (Schwalbea americana) is a federally 
listed endangered species with a Natural 
Heritage rank of G2. The historical range of this 
species extended from Mississippi to 
Massachusetts; the plant is currently known 
from about 20 populations in five states, mostly 
in South Carolina. The most significant threat 
to this species is fire suppression, which allows 
plant succession to proceed to the point where 
there is not enough light for the plant to com- 
pete successfully. Habitat loss has also caused 
the extirpation of several Schwalbea popula- 
tions. For rare species such as S. americana, 
further state-level extirpations could seriously 
affect the species' survival. 

Wetland Species 

Although there are fewer than 7,000 native 
wetland vascular plant species in the United 
States, plants that occur mostly in wetlands are 
more likely to be extirpated from at least one 
state. Based on the USFWS National Wetlands 
Inventory (Reed 1988), about half of the poten- 
tially extirpated species are either obligate (see 
glossary) or facultative (see glossary) wetland 
species. 

Wetlands and aquatic ecosystems have been 
severely affected in the United States; approxi- 
mately 53% of these ecosystems have been 
destroyed in the 48 contiguous states (Dahl 
1990). Aquatic species frequently have specific 
habitat requirements and can be threatened by 
both habitat loss and changes in local hydrolo- 
gy. In the mid-Atlantic region, several intertidal 
vascular plants have been extirpated from the 
Delaware River system because of habitat alter- 
ation (Ferren and Schuyler 1980). 

Possibly Extinct Species 

About 90 mainland U.S. and 1 10 Hawaiian 
vascular plant species may be extinct, accord- 
ing to records of the USFWS and The Nature 
Conservancy (Russell and Morse 1992). For 




Proportion rare plants (%) 

■ >29 

■ 12.0 — 170 

□ 8.0 — 1 1.9 

□ 5.0-7.9 

□ 2.6-4.9 

□ 0-2.5 



Fig. 3. The proportion of globally 
rare vascular plant species (ranked 
Gl, rarest, to G3, more common) 
in the native flora of each U.S. 
state. 




Proportion of state flora lost (%) 

■ >1 5 (Delaware) 

■ 5.0-14.9 
n 3.0-4.9 

□ 1.0-2.9 

□ <1.0 



Fig. 4. The proportion of species 
reported potentially extirpated 
from the native flora of each U.S. 
state. 



208 



Plains — Our Living Resources 



example, Nuttall's mudwort (Micranthemum 
micranthemoides) has been recorded from 
Delaware, the District of Columbia, Maryland, 
New Jersey, New York, Pennsylvania, and 
Virginia, but despite searches, it has not defi- 
nitely been seen since September 1941. 

Several species of U.S. plants are extirpated 
from the wild, but still exist in cultivation. Most 
familiar of these is the Franklinia {Franklinia 
alatamaha), a small tree known historically 
only from the Altamaha River in southeastern 
Georgia, but which is now widely cultivated as 
an ornamental in eastern states. 

Ongoing fieldwork has resulted in the redis- 
covery of many species. The running buffalo 
clover (Trifolium stoloniferum) was rediscov- 
ered in West Virginia in 1983 (Bartgis 1985) 
and has been found subsequently in Indiana, 
Kentucky, Missouri, and Ohio. In Oregon, a 
population of Lomatium peckianum was located 
in 1983 for the first time in more than 50 years. 
The discovery of additional populations has 
changed the species" federal status from a cate- 
gory 1 candidate to a former candidate (Kagan 
and Vrilakas 1993). In Montana, several recent 
rediscoveries have occurred, including a 1985 
rediscovery of Trifolium microcephalism, a 
species of clover not seen since it was first col- 
lected by Meriwether Lewis in 1805 or 1806 
(Hoy 1993). Likewise, during the 1991 field 
season the yellow passionflower (Passiflora 
lutea) was located at two sites in Delaware for 
the first time since the early 1800's (Clancy 
1993). These examples illustrate the importance 
of ongoing inventories as well as the dynamic 
nature of local and regional floras. 

Threats to Diversity 

Habitat alteration and incompatible land use 
are the major threats to most rare U.S. plant 
species. Apart from certain species of cacti, gin- 
seng, and various showy wildflowers, relatively 
few rare U.S. plants are primarily threatened by 
overcollecting. Global climate change (Peters 
and Lovejoy 1992; Morse et al. 1993) and sea- 
level rise (Reid and Trexler 1991) may pose 
additional threats to some native U.S. plant 
species. 

Species at higher risk of extinction usually 
include those having small geographic ranges, 
narrow habitat requirements, unusual life histo- 
ries, or vulnerability to exotic pests or diseases. 
In addition, reduced biodiversity of local floras 
is of high concern, even if plants lost from a 
particular geographical region are common and 
secure elsewhere. Finally, depletion of even 
widespread species can occur if exploitation or 
habitat destruction occurs beyond a sustained- 
yield rate. 



Assessment of the causes and patterns of 
species losses in the United States, combined 
with ongoing documentation of natural diversi- 
ty and studies of rarity, endangerment, and 
threats, will refine conservation priorities by 
identifying species or areas that will most bene- 
fit from further protection and research. 
Analyses of ongoing inventory and monitoring 
work could provide early warnings of wide- 
spread threats to biological diversity, thereby 
perhaps improving the protection of both rare 
and more common plants and allowing the 
development and implementation of conserva- 
tion strategies before crises occur. 

References 

Bartgis. R.L. 1985. Rediscovery of Trifolium stoloniferum 

Muhl. ex A. Eaton. Rhodora 87:425-429. 
Carlquist. S. 1970. Hawaii: a natural history. Natural 

History Press, Garden City. NY. 463 pp. 
Clancy. K. 1993. The yellow passionflower. Passiflora lutea 

L., rediscovered in Delaware. Castanea 58:153-155. 
Dahl, T.E. 1990. Wetlands losses in the United States 1780s 

to 1980s. U.S. Fish and Wildlife Service. Washington, 

DC. 13 pp. 
Federal Register. 1993. Plant taxa for listing as endangered 

or threatened species: notice of review. Federal Register 

58:51144-51190. 
Ferren, W.R., and A.E. Schuyler. 1980. Intertidal vascular 

plants of river systems near Philadelphia. Proceedings of 

the Academy of Natural Sciences of Philadelphia 

132:86-120. 
Hoy, J. 1993. Rediscovering lost species. Kelseya [Montana 

Native Plant Society] 6:5. 
Jenkins. R.E. 1985. Information methods: why the Heritage 

programs work. The Nature Conservancy News 35:21- 

23. 
Kagan. J., and S. Vrilakas. 1993. Extinct and extirpated 

plants from Oregon. Kalmiopsis [Native Plant Society of 

Oregon] 3:12-16. 
Kartesz, J.T 1992. Preliminary counts for native vascular 

plant species of U.S. states and Canadian provinces. 

Biodiversity Network News [The Nature Conservancy] 

5:6. 
Kartesz. J.T. 1994. A synonymized checklist of the vascular 

flora of the United States. Canada, and Greenland. 2nd 

ed. Timber Press. Portland. OR. 622 pp. 
McKnight. B.N.. ed. 1991. Biological pollution: the control 

and impact of invasive exotic species. Indiana Academy 

of Science. Indianapolis. 261 pp. 
Morse. L.E., L.S. Kutner, G.D. Maddox, J.T. Kartesz, L.L. 

Honey. CM. Thurman. and S.J. Chaplin. 1993. The 

potential effects of climate change on the native vascular 

flora of North America: a preliminary climate-envelopes 

analysis. Report TR- 103330. Electric Power Research 

Institute. Palo Alto. CA. 120 pp. 
Peters, R.L.. and T.L. Lovejoy. eds. 1992. Global wanning 

and biological diversity. Yale University Press. New 

Haven, CT. 386 pp. 
Reed, P.B.. Jr. 1988. National list of plant species that occur 

in wetlands: 1988 national summary. U.S. Fish and 

Wildlife Service. Washington. DC. 244 pp. 
Reid. W.V.. and M.C. Trexler. 1991. Drowning the national 

heritage: climate change and U.S. coastal biodiversity. 

World Resources Institute. Washington. DC. 48 pp. 
Russell. C.A.. and L.E. Morse. 1992. Plants. Biodiversity 

Network News [The Nature Conservancy] 5:4. 
Smith. Clifford W. 1989. Non-native plants. Pages 60-69 in 

C.P. Stone and D.B. Stone, eds. Conservation biology in 

Hawai'i. University of Hawaii Cooperative National Park 

Resources Study Unit. Honolulu. 



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Snyder, D.B. 1993. Extinct, extant, extirpated, or historical? 

Or in defense of historical species. Bartonia 57. 

Supplement:50-57. 
U.S. Congress, Office of Technology Assessment. 1993. 

Harmful non-indigenous species in the United States. 

U.S. Government Printing Office OTA-F-565 

(September). 391 pp. 



USFWS 1994. Box score: listings and recovery plans. U.S. 

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of the flowering plants of Hawai'i. University of Hawaii 

Press, Honolulu. 1,853 pp. 



For further information: 

Larry E. Morse 

The Nature Conservancy 

1815 N.Lynn St. 

Arlington, VA 22209 



New York, the third most populous state, has 
highly varied topography, geology, soils, 
and climate, and a complex history of land use, 
all of which are reflected in a rich flora of native, 
introduced, and opportunistic species. Large 
parts of the state support beech-maple, oak- 
chestnut (now modified as a result of the elimi- 
nation of chestnut), or hemlock-northern hard- 
wood forest, and there are extensive tracts of red 
spruce-balsam fir forest in the Adirondack and 
Catskill mountains. Alpine tundra is present on 
the highest Adirondack peaks at elevations above 
about 1,372 m (4,500 ft), while salt marshes, 
freshwater ponds, and dwarf pine barrens occur 
at or near sea level on Long Island. Almost all 
land in the state has been glaciated and therefore 
available for plant occupation no longer than 
18,000 years. In 1880 nearly 78% of the state's 
land was in farms or farm woodlots, but by 1980, 
61% of New York was classified as forested. 

The flora of New York is an economically 
important resource and the foundation of healthy 
sustainable environmental systems. The state's 
flora and its composition have been studied since 
the early 1800's, allowing researchers to present 
trends in the numbers of vascular plant and moss 
species. In our work, we have emphasized the 
study of voucher (see glossary) specimens, 
which allow us and our successors to verify iden- 
tifications and evaluate the application of species 
concepts of other researchers. 

Status 

Organized study of the New York flora began 
in 1836 with a botanical survey that was a part of 
the New York State Geological and Natural 
History Survey. This survey led to the publica- 
tion of John Torrey 's A Flora of the State of New- 
York (Torrey 1843). The state's plant resources 
continued to be investigated at the New York 
State Museum under government sponsorship 
that began in 1 867 and continues to the present. 
The regionally significant herbarium and exten- 
sive data collections that have resulted from this 
research and exploration provide the documenta- 
tion for this article as well as our ongoing work 
and information from other important botanical 
collections. 

Totals for the major groups of mosses and 
vascular plants (as of February 1 994) are given in 
Table 1 , and increases in the numbers of known 
species are listed in Table 2. Torrey's 1843 flora 



enumerated 1,452 species, while a 1994 com- 
pendium (R.S. Mitchell, unpublished data) lists 
3,451, an increase of 58%. The differences, in 
part, are due to a dramatic increase in the number 
of reported non-native species, of which 77% 
(1,122 of 1,449) are naturalized (naturally repro- 
ducing and spreading). The differences are also 
due to a significant rise in the number of species 
recognized as indigenous to the state (an increase 
of 7 1 1 ). Native species from other parts of the 
United States are listed i