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Full text of "Snake River birds of prey research project : annual report, 1989"

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U.S. Department of the Interior 

BUREAU OF LAND MANAGEMENT 
Boise District, Idaho 



As the Nation's principal conservation agency, the Department of the 
Interior has responsibility for most of our nationally owned public lands 
and natural resources. This includes fostering the wisest use of our land 
and water resources, protecting our fish and wildlife, preserving the 
environmental and cultural values of our national parks and historical 
places, and providing for the enjoyment of life through outdoor recreation. 
The Department assesses our energy and mineral resources and works to assure 
that their development is in the best interests of all our people. The 
Department also has a major responsibility for American Indian reservation 
communities and for people who live in Island Territories under U.S. 
administration . 



1 BLM LIBRARY ^ XL 

SC-653, BLDG. 50 * ?s 

DENVER FEDERAL CiNTIR ^ 

P. 0. BOX 25047 
DENVER, CO 80225-0047 



SNAKE RIVER BIRDS OF PREY RESEARCH PROJECT 
ANNUAL REPORT 
1989 



Karen Steenhof 
Editor 



NOT FOR PUBLICATION 



The data presented herein are preliminary and may be inconclusive. 
Permission to publish or cite any of these materials is therefore 
withheld pending specific authorization of the Boise District, BLM, 
and the specific Principal Investigator. 



Michael N. Kochert J. David Brunner 

Research Leader Boise District Manager 



Delmar Vail 
Idaho State Director 



PREFACE 



This report summarizes research and monitoring activities in the Snake 
River Birds of Prey Area during calendar year 1989. 

In 1989, the BLM Birds of Prey Research staff, in consultation with the 
Idaho Army National Guard, completed a research plan to investigate the 
effects of habitat alteration on the raptors, their prey, and their habitat 
in the SRBOPA. Wildfire and National Guard activities are the 2 main 
activities that will be addressed by the proposed research, though some 
information will be collected on grazing and seedings. In 1989 study design 
teams were formed and 4 workshops were held, including an integration 
workshop. Work began on specific designs for each study and a Statement of 
Work was completed for the TGS study in 1989. As a result of an identified 
information need Drs. Mark Fuller (Patuxent Wildlife Research Center) and Kim 
Titus conducted a pilot radio telemetry study in the OTA. 

Work continued on copperative studies in 1989. Two graduate studies by 
students from Boise State University continued in 1989. Helen Ulmschneider 
continued an investigation of long-eared owl post-fledging activity, and Dawn 
McAnnis Gerhardt completed the second year of a study on ferruginous hawk 
habitat use. The ferruginous hawk study was supported jointly by Boise State 
University and the Bureau of Land Management. Studies of the effects of fire 
on soil microbial communities were also continued by Boise State University 
faculty members, Marcia Wicklow-Howard and Robert Rychert. Claire Fuller of 
Oregon State University initiated a study of Townsend's ground squirrel 
mating systems and behavior. 

Two cooperative studies with utility companies were completed in 1989. 
Final reports were completed for the Idaho Power /Pacific Gas and Electric 
Companies cooperative study on prairie falcons and the Pacific Power and 
Light Company (PP&L) raven roosting study. Allison Beck was contracted to 
monitor the response of roosting ravens to installation of new shields and 
pegging at the Initial Point roost. The PP&L nesting study continued at the 
same levels as in past years. 

Other 1989 field activities included continuing investigations of common 
barn-owl feeding ecology by Dr. Carl Marti of Weber State College, assessment 
of nest box use by American kestrels by Karen Steenhof , and studies of 
western screech-owl and northern saw-whet owls using nest boxes in the SRBOPA 
by Jeff Marks and John Doremus. 

Monitoring of prey was carried out by the Bruneau Resource Area staff and 
Research Staff volunteers in 1989. One new jackrabbit spotlighting transect 
was established within the Orchard Training Area with the assistance of Idaho 
Army National Guard personnel. Monitoring of winterfat seeding projects was 
continued by the U.S. Forest Services Laboratory and the Idaho BLM State 
Office and greenstrip monitoring was initiated by the Idaho BLM State Office 
in 1989. 

Although the main thrust for 1989 was development of the BLM/IDARNG 
research plan and continuation of cooperative research projects, work still 



continued on Technology Transfer. Fourteen scientific papers were published 
and/or accepted for publication in 1989, and Birds of Prey Research Project 
staff members and associates made 14 technical presentations at meetings. 



ACKNOWLEDGMENTS 



The Bureau of Land Management wishes to thank those 
agencies and individuals who assisted with the project. 
Appreciation is extended to the Idaho Department of Fish 
and Game and the U.S. Fish and Wildlife Service for special 
permits and assistance. Special thanks go to all other 
individuals who volunteered their services. 



COOPERATING AGENCIES AND INSTITUTIONS 

Boise State University, Raptor Research Center 

College of Idaho 

Idaho Army National Guard 

Idaho Department of Fish and Game 

Idaho Department of Transportation 

Idaho Department of Water Resources 

Idaho Power Company 

Idaho State University 

Pacific Gas & Electric Company 

Pacific Power and Light Company 

University of Idaho 

University of Wisconsin 

USDA Agricultural Research Service 

U.S. Fish and Wildlife Service 

U.S. Forest Service Intermountain Research Station 

Weber State College 

World Center for Birds of Prey 



TABLE OF CONTENTS 



PART I. TECHNOLOGY TRANSFER 



Page 



Summary of Project Publications 2 

1989 Technical Presentations 8 

PART II. PROGRESS REPORTS 

Nesting Density and Productivity of Golden Eagles in and near the 

Snake River Birds of Prey Area. 13 

Monitoring Long-eared Owl Occupancy in the Snake River Birds 

of Prey Area. 19 

Raptor and Raven Nesting on the PP&L Malin to Midpoint 500-kV 

Transmission Line. 22 

Implications of Communal Roosting by Common Ravens to Operation and 

Maintenance of the Malin to Midpoint 500-kV Transmission Line. 37 

Use of Nest Boxes by American Kestrels in Southwestern Idaho. 47 

Feeding Ecology of the Barn Owl in the Snake River Birds 

of Prey Area. 50 

Nest Box Use, Reproduction, Movements, Food Habits, and Annual 
Cycle of Body Mass of Western Screech-Owls in the Snake River 
Birds of Prey Area. 55 

Post-nesting Ecology of Long-eared Owls in the Snake River Birds 

of Prey Area, Idaho. 58 

Home Range and Habitat Use of Ferruginous Hawks in the Snake River 

Birds of Prey Area. 78 

Morphometric and Genetic Variation in Ferruginous Hawk Populations. 82 

Testing Performance of Wildlife Telemetry Equipment in the Orchard 

Training Area. 84 

Abundance of Lagomorphs and Rodents in the Snake River Birds 

of Prey Area. 89 

Townsend's Ground Squirrel Relative Abundance in the Snake River 

Birds of Prey Area. 96 

Townsend's Ground Squirrel Diets in the Snake River Birds 

of Prey Area. 104 

Factors Affecting the Mating System in Townsend's Ground Squirrels. 123 

Parasites and Population Ecology in Kangaroo Rats. 127 

Effect of Wildfires on Soil Microbial Communities. 130 

Winterfat Seeding Projects in the Snake River Birds of Prey Area. 135 

Environmental Monitoring in the Idaho Army National Guard 

Orchard Training Area. 142 

Establishment of Monitoring Studies on Greenstrip Projects 

in the Snake River Birds of Prey Area. 148 



PART I 
TECHNOLOGY TRANSFER 



Snake River Birds of Prey Area 
Technical Articles Published And/Or Accepted for Publication 

Allen, G.T., R.K. Murphy, K. Steenhof, and S.W. Piatt. 1986. Late fledging 
dates, renesting, and large clutches of prairie falcons. Wilson Bull. 
98:463-465. 

Collopy, M.W. 1983. A comparison of direct observations and collections of 
prey remains in determining the diet of golden eagles. J. Wildl. Manage. 
47:360-368. 

Collopy, M.W. 1983. Foraging behavior and success of golden eagles. Auk 
100:747-749. 

Collopy, M.W. 1984. Parental care and feeding ecology of golden eagle 
nestlings. Auk 101:753-760. 

Collopy, M.W. 1986. Food consumption and growth energetics of nestling 
golden eagles. Wilson Bull. 98:445-458. 

*Collopy, M.W., and T.C. Edwards, Jr. 1989. Territory size, activity 

budget, and role of undulating flight in nesting golden eagles. J. Field 
Ornith. 60:43-51. 

Craig, T.H., E.H. Craig, and J.S. Marks. 1982. Aerial talon-grappling in 
northern harriers. Condor 84:239. 

*Diller, L.V. 1990. A field observation on the feeding behavior of Crotalus 
viridis lutosus. J. Herpetology. Accepted 1989. 

Diller, L.V., and D.R. Johnson. 1982. Ecology of reptiles in the Snake 
River Birds of Prey Area. U.S. Dep. Inter., Bur. Land Manage., Boise, 
Idaho. 107pp. 

Diller, L.V., and D.R. Johnson. 1988. Food habits, consumption rates, and 
predation rates of western rattlesnakes and gopher snakes in southwestern 
Idaho. Herpetologica 44:228-233. 

Diller, L.V. , and R.L. Wallace. 1981. Additional distribution records and 
abundance of three species of snakes in southwestern Idaho. Great Basin 
Nat. 41:154-157. 

Diller, L.V. , and R.L. Wallace. 1986. Aspects of the life history and 
ecology of the desert night snake, Hypsiglena torquata deserticola : 
Colubridae in southwestern Idaho. Southwestern Nat. 31:55-64. 

Doremus, J.H., and A.R. Bammann. 1982. The Snake River Birds of Prey Study 
Area bird list U.S. Dep. Inter., Bur. Land Manage., Boise, Idaho. 

Edwards, T.C, Jr., and M.W. Collopy. 1983. Obligate and facultative brood 
reduction in eagles: an examination of factors that influence 
fratricide. Auk 100:630-635. 



*Edwards, T.C. , Jr., and M.W. Collopy. 1989. Response to G.R. Bortolotti 
and T.W. Arnold. Auk 106:523-524 

Edwards, T.C, Jr., M.W. Collopy, K. Steenhof, and M.N. Kochert. 1988. Sex 
ratios of fledgling golden eagles. Auk 105:793-796. 

Edwards, T.C, Jr., and M.N. Kochert. 1986. Use of body weight and length 
of footpad as predictors of sex in golden eagles. J. Field Ornithol. 
57:317-319. 

*Engel, K.A., and L.S. Young. 1989. Evaluation of techniques for capturing 
common ravens in southwestern Idaho. North Amer. Bird Bander. 14:5-8 

*Engel, K.A. , and L.S. Young. 1989. Spatial and temporal patterns in the 
diet of common ravens in southwestern Idaho. Condor 91:372-378. 

Evans, D.L. 1982. The wingloading method of weight control. Hawk Chalk 
21:55-59. 

Groves, CR. , and K. Steenhof. 1988. Responses of small mammals and 
vegetation to wildfire in shadscale communities of southwestern Idaho. 
Northwest Sci. 62:205-210. 

*Holthuijzen, A.M. A. 1990. Prey delivery, caching, and retrieval rates in 
nesting prairie falcons. Condor. Accepted 12/15/89. 

*Holthuijzen, A.M. A. 1990. Behavior and productivity of nesting prairie 
falcons in relation to construction activities at Swan Falls Dam. Final 
Report. Idaho Power Co., Boise, Idaho. 77pp. 

Holthuijzen, A.M. A. , P. A. Duley, J.C Hagar, S.A. Smith, and K.N. Wood. 
1987. Piracy, insectivory, and cannibalism of prairie falcons ( Falco 
mexicanus ) nesting in southwestern Idaho. J. Raptor Res. 21:32-33. 

Holthuijzen, A.M. A. , P. A. Duley, J.C Hagar, S.A. Smith, and K.N. Wood. 
1987. Bathing behavior of nesting prairie falcons ( Falco mexicanus ) in 
southwestern Idaho. Wilson Bull. 99:135-136. 

Hyde, W.F. , A. Dickerman, and D. Stone. 1982. Development versus 

preservation in the Snake River Birds of Prey Conservation Area. Am. J. 
Agric. Econ. 64:756-760. 

Innis, G. , J. Wiens, M. El-Bayoumi, L. Nelson, R. Ryel, K. Smith, J. 

Wlosinski, G. Worthen. 1979. Birds of Prey Study Area simulation model, 
Vol. 1. Final Report. Utah State Univ. Wildlife Science Rep. 7. Logan, 
Utah. 277pp. 

Johnson, D.R., N.C Nydegger, and G.W. Smith. 1987. Comparison of 
movement-based density estimates for Townsend ground squirrels. J. 
Mammal. 68:689-691. 

Knopf, F.L. , and T.E. Olson. 1984. Naturalization of Russian olive: 

implications to Rocky Mountain wildlife. Wildl. Soc. Bull. 12:289-298. 



Kochert, M.N. 1980. Golden eagle reproduction and population changes in 
relation to jackrabbit cycles: implications to eagle electrocutions. 
Pages 71-86 in R.P. Howard and J.F. Gore, eds. Proceedings of a workshop 
on raptors and energy developments U.S. Dep. Inter., Fish and Wildl. 
Serv. , Boise, Idaho. 125pp. 

Kochert, M.N. 1986. Raptors. Chapter 16 in A.Y. Cooperrider, R.J. Boyd, 
and H.R. Stuart, eds. Inventory and monitoring of wildlife habitat. U.S. 
Dep. Inter., Bur. Land Manage . , Denver, Colo. 858pp. 

*Kochert, M.N. 1989. Responses of raptors to livestock grazing in the 
western United States. Pages 194-203 in B.A. Giron Pendleton, et al., 
eds., Proceedings of the Western Raptor Management Symposium and 
Workshop. Natl. Wildl. Fed., Washington D.C. 

Kochert, M.N. , B.A. Millsap, and K. Steenhof. 1988. Effects of livestock 
grazing on raptors with emphasis on the southwestern U.S. Pages 325-334 
in R. L. Glinski et al., eds. Proceedings of the Southwestern Raptor 
Management Symposium and Workshop. Natl. Wildl. Fed., Washington, D.C. 

Kochert, M.N. , and M. Pellant. 1986. Multiple use in the Snake River Birds 
of Prey Area. Rangelands 8:217-220. 

Kochert, M.N. , K. Steenhof, and M.Q. Moritsch. 1983. Evaluation of 

patagial markers for raptors and ravens. Wildl. Soc. Bull. 11:271-281. 

Marks, J.S. 1983. Prolonged incubation by a long-eared owl. J. Field 
Ornithol. 54:199-200. 

Marks, J.S. 1984. Unusual nest sites of a western screech-owl and an 
American kestrel. Murrelet 64:96-97. 

Marks, J.S. 1984. Feeding ecology of breeding long-eared owls in 
southwestern Idaho. Can. J. Zool. 62:1528-1533. 

Marks, J.S. 1985. Yearling male long-eared owls breed near natal nest. 
J. Field Ornithol. 56:181-182 

Marks, J.S. 1986. Nest-site characteristics and reproductive success of 
long-eared owls in southwestern Idaho. Wilson Bull. 98:547-560. 

Marks, J.S., and J.H. Doremus. 1988. Breeding season diet of northern 
saw-whet owls in southwestern Idaho. Wilson Bulletin. 100:690-694. 

Marks, J.S., J.H. Doremus, and A.R. Bammann. 1980. Black-throated sparrows 
breeding in Idaho. Murrelet 61:112-113. 

*Marks, J.S., J.H. Doremus, and R.J. Cannings. 1989. Polygyny in the 
northern saw-whet owl. Auk 106:732-734. 

Marks, J.S., and V.A. Marks. 1981. Comparative food habits of the 

screech owl and long-eared owl in southwestern Idaho. Murrelet 62:80-82. 



Marks, J.S. , and CD. Marti. 1984. Feeding ecology of sympatric barn owls 
and long-eared owls in Idaho. Ornis Scandinavica 15:135-143. 

Marks, J.S., and R.L. Redmond. 1987. Parent-offspring conflict and natal 
dispersal in birds and mammals: comments on the Oedipus hypothesis. Am. 
Nat. 129:158-164. 

Marks, J.S., and E. Yensen. 1980. Nest sites and food habits of long-eared 
owls in southwestern Idaho. Murrelet 61:86-91. 

Marti, CD. 1988. A long-term study of food-niche dynamics in the common 
barn-owl: comparisons within and between populations. Can. J. Zool. 
66:1803-1812. 

Martin, J.W. 1987. Behavior and habitat use of breeding northern harriers 
in southwestern Idaho. J. Raptor Res. 21:57-66. 

Messick, J. P., and M.G. Hornocker. 1981. Ecology of the badger in 
southwestern Idaho. Wildl. Monogr. 76. 53pp. 

Messick, J. P., G.W. Smith, and A.M. Barnes. 1983. Serologic testing of 
badgers to monitor plague in southwestern Idaho. J. Wildl. Diseases 
19:1-6. 

Messick, J.P. , M.C Todd, and M.G. Hornocker. 1981. Comparative ecology of 
two badger populations. Pages 1290-1303 in J. A. Chapman and D. Pursley, 
eds. Proceedings of the World Furbearer Conference. Frostburg, 
Maryland. 

Moritsch, M.Q. 1983. Photographic guide for aging nestling prairie 
falcons. U.S. Dep. Inter., Bur. Land Manage . , Boise, Idaho. 15pp. 

Moritsch, M.Q. 1983. Photographic guide for aging nestling red-tailed 
hawks. U.S. Dep. Inter., Bur. Land Manage., Boise, Idaho. 14pp. 

Moritsch, M.Q. 1985. Photographic guide for aging nestling ferruginous 
hawks. U.S. Dep. Inter., Bur. Land Manage., Boise, Idaho. 21pp. 

*Nydegger, N.C, and D.R. Johnson. Size and overlap of Townsend ground 
squirrel home ranges. Great Basin Nat. 49:108-110. 

Nydegger, N.C, and G.W. Smith. 1986. Prey populations in relation to 
Artemisia vegetation types in southwestern Idaho. Pages 152-156 in E.D. 
McArthur and B.L. Welch, eds. Proceedings of a Symposium on the biology 
of Artemisia and Chrysothamnus . U.S. Dep. Agric, For. Serv. , 
Intermountain Res. Sta. , Ogden, Utah. 398pp. 

Olendorff, R.R., and M.N. Kochert. 1977. Land management for the 

conservation of birds of prey. Pages 294-307 in R.D. Chancellor, ed. 
Proceedings of the World Conference on Birds of Prey. Int. Counc. for 
Bird Preservation, Great Britain. 442pp. 



*01endorff, R.R. , D.D. Bibles, M.T. Dean, J.R. Haugh, and M.N. Kochert. 
1989. Raptor habitat management under the U.S. Bureau of Land 
Management Multiple-Use Mandate. Raptor Res. Rep. 8:1-80. 

Powers, L.R., T.H. Craig, and J. Martin. 1984. Nest defense by northern 
harriers against the coyote in southwestern Idaho. Raptor Res. 18:78-79. 

Smith, G.W., and D.R. Johnson. 1985. Demography of a Townsend ground 
squirrel population in southwestern Idaho. Ecology 66:171-178. 

Smith, G.W., and N.C. Nydegger. 1985. A spotlight line-transect method 
for surveying jack rabbits. J. Wildl. Manage. 49:699-702. 

Smith, G.W., N.C. Nydegger, and D.L. Yensen. 1984. Passerine bird 
densities in shrubsteppe vegetation. J. Field Ornithol. 55:261-264. 

Steenhof, K. 1982. Use of an automated geographic information system by 
the Snake River Birds of Prey Research Project. Comput. Environ. Urb. 
Systems 7:245-251. 

Steenhof, K. 1983. Prey weights for computing percent biomass in raptor 
diets. Raptor Res. 17:15-27. 

Steenhof, K. 1984. Book review: behavior of fledgling peregrines. 
Murrelet 65:31. 

Steenhof, K. 1984. Use of an interspecific communal roost by wintering 
ferruginous hawks. Wilson Bull. 96:137-138. 

Steenhof, K. 1987. Assessing raptor reproductive success and productivity. 
Pages 157-170 in B.A. Giron Pendleton, B.A. Millsap, K.W. Cline, and D.M. 
Bird, eds. Raptor management techniques manual. Natl. Wildl. Fed., 
Washington, D.C. 

Steenhof, K. 1988. Book review: raptor conservation in the next 50 years. 
Wilson Bull. 100:338-339. 

Steenhof, K. 1988. Identifying potential bald eagle nesting habitat: a 
review of the state of the art. Pages 31-59 in D. Garcelon and G.W. 
Roemer, eds., Proceedings of the international symposium on raptor 
reintroduction, 1985. Institute for Wildlife Studies, Areata, 
California. 

Steenhof, K. , and M.N. Kochert. 1982. Nest attentiveness and feeding rates 
of common ravens in Idaho. Murrelet 63:30-32. 

Steenhof, K. , and M.N. Kochert. 1982. An evaluation of methods used to 
estimate raptor nesting success. J. Wildl. Manage. 46:885-893. 

Steenhof, K. , and M.N. Kochert. 1985. Dietary shifts of sympatric buteos 
during a prey decline. Oecologia 66:6-16. 



6 



Steenhof, K. , and M.N. Kochert. 1988. Dietary responses of three raptor 
species to changing prey densities in a natural environment. J. Animal 
Ecol. 57:37-48. 

Steenhof, K. , M.N. Kochert, and J.H. Doremus. 1983. Nesting of subadult 
golden eagles in southwestern Idaho. Auk 100:743-747. 

Steenhof, K. , M.N. Kochert, and M.Q. Moritsch. 1984. Dispersal and 

migration of southwestern Idaho raptors. J. Field Ornithol. 55:356-368. 

*Wicklow-Howard, M. 1989. The occurrence of vesicular-arbuscular 

mychorrhizae in burned areas of the Snake River Birds of Prey Area, 
Idaho. Mycotaxon 34:253-257. 

Yensen, D.L., and G.W. Smith. 1984. Big sagebrush-winterfat and big 
sagebrush-Nuttall saltbush mosaic vegetation in southwestern Idaho. 
Pages 28-33 in A.R. Tiedemann, E.D. McArthur, H.C. Stutz, R. Stevens, and 
K.L. Johnson, eds. Proceedings of the symposium on the biology of 
Atriplex and related chenopods. Gen. Tech. Rep. INT-172. U.S. Dep. 
Agric, For. Serv., Intermountain For. Range Exp. Sta. , Ogden, Utah. 

Yensen, D. 1980. A grazing history of southwestern Idaho with emphasis on 
the Birds of Prey Study Area. U.S. Dep. Inter., Bur. Land Manage., 
Boise, Idaho. 82pp. 

Yensen, D.L. 1981. The 1900 invasion of alien plants into southern Idaho. 
Great Basin Nat. 41:176-183. 

*Young, L.S. 1989. Effects of agriculture on raptors in the western United 
States an overview. Pages 209-218 in B.A. Giron Pendleton et al., eds., 
Proceedings of the Western Raptor Management Symposium and Workshop. 
Natl. Wildl. Fed., Washington D.C. 

Young, L.S., J.G. Crenshaw, and L.L. Crenshaw. 1988. Food caching by a 
short-eared owl . Murrelet 69 : 39 . 

*Young, L.S., and K.A. Engel. 1988. Implications of communal roosting by 
common ravens to operation and maintenance of Pacific Power and Light 
Company's Malin to Midpoint 500 kV transmission line. Final Report. 
Pacific Power Env. Serv. Dep. Portland, OR. 

Young, L.S., and M.N. Kochert. 1987. Marking techniques. Pages 125-156 in 
B.A. Giron Pendleton, B.A. Millsap, K.W. Cline, and D.M. Bird, eds. 
Raptor management techniques manual. Natl. Wildl. Fed., Washington, D.C. 



Published and/or accepted for publication in 1989. Reprints of most of 
these articles are available from the Birds of Prey Research Project, 
Boise District, BLM, 3948 Development Avenue, Boise, ID 83709. 



1989 Birds of Prey Research Technical Presentations 



1/28/89 



2/21/89 

2/24/89 

2/24/89 

3/14/89 
3/17/89 



Holthuijzen, A.M. A. , R.D. Williams . M.N. Kochert, and L.S. Young. 
Mate guarding in the Prairie Falcon: with particular reference to 
the sperm competition hypothesis. Annual Meeting of the Western 
section of the Wildlife Society. Redding, California. 

Young, L. Bald eagle habitat management: an international 
perspective. Oregon Eagle Foundation Bald Eagle Habitat Management 
Workshop. Hood River, Oregon. 

Holthuijzen, A.M. A. Copulation frequency and timing in the Prairie 
Falcon. Annual Meeting of the Idaho Chapter of The Wildlife 
Society. Boise, Idaho. 

Ulmschneider, H. Post-nesting movements of long-eared owls in 
southwestern Idaho. Annual Meeting of the Idaho Chapter of the 
Wildlife Society. Boise, Idaho. 

Steenhof, K. Bald eagle recovery. Graduate seminar on Eagle 
Biology. Boise State University. Boise, Idaho. 

Young, L. , K.A. Engel, K. Steenhof, M.N. Kochert, and J. A. Roppe. 
Interactions between ravens and transmission lines. 14th Annual 
Meeting and Symposium of the Desert Tortoise Council, Mesquite, 
Nevada. 



3/21/89 



4/15/89 



4/25/89 
4/27/89 



6/23/89 



6/25/89 



McAnnis, P., and M. J. Bechard. Home range and habitat use of 
Ferruginous Hawks in the Snake River Birds of Prey Area. Northwest 
Science Meetings. Richland, Washington. 

fog 61 * K - Communal roosting of Common Ravens in southwestern 
Idaho. Graduate Seminar. University of Wisconsin, Madison. 

Kochert, M. N. Reproductive performance, food habits, movements, 
and subadult breeding of Golden Eagles. Graduate seminar on Eagle 
Biology. Boise State University. Boise, Idaho. 

Marti, CD. Feeding, Reproduction, movements, and survival of the 
common barn-owl in the Great Basin. Symposium on Long-term 
Ecological Studies of Birds. 59th Annual Meeting of the Cooper 
Ornithological Society. Moscow, Idaho. 



Steenhof, K^ Variations in Golden Eagle reproductive rates: 
effects of prey and weather. 59th Annual Meeting. Cooper 
Ornithological Society. Moscow, Idaho. 



The 



10/12/89 Spahr, R. , M. Bechard, and K. Steenhof . Factors affecting 

distribution of wintering bald eagles on the Boise River in Idaho. 
Joint meeting, Raptor Research Foundation and ICBP World Working 
Group of Birds of Prey. Vera Cruz, Mexico. 

10/13/89 Ulmschneider , H. Post-nesting movements of long-eared owls in 
southwest Idaho. Joint Meeting, Raptor Research Foundation and 
ICBP World Working Group of Birds of Prey. Vera Cruz, Mexico. 



9 



PART II 
PROGRESS REPORTS 



TITLE: Nesting Density and Productivity of Golden Eagles in and near 
the Snake River Birds of Prey Area. 

INVESTIGATORS: Karen Steenhof , BLM Birds of Prey Research 

Michael N. Kochert, BLM Birds of Prey Research 

OBJECTIVES : 

1. To determine occupancy, nesting success, and productivity at 
traditional golden eagle ( Aquila chrysaetos ) nesting territories. 

2. To compare occupancy and productivity of golden eagle pairs in the 
Snake River Birds of Prey Area (SRBOPA) with those of eagle pairs in 
the Comparison Area. 



ANNUAL SUMMARY 

In 1989 the number of occupied golden eagle territories in the SRBOPA was 
lower than in 1988, but percent of eagle pairs breeding and percent of 
breeding pairs successful were both higher in 1989 than in 1988. Overall, 
eagle productivity was higher than it has been since 1983 . As in the past 5 
years, eagle productivity was lower in the SRBOPA than in the Comparison 
Area. Eagles that nested on a transmission line were more productive than 
eagles that nested on cliffs. 



METHODS 

Golden eagle territories in the SRBOPA and Comparison Area (Fig. 1) were 
surveyed for occupancy from a Hiller/Soloy jet helicopter on 16 March. Some 
territories on or near the Pacific Power and Light Company (PP&L) 500-kV 
transmission power line were also checked from a Bell 206 Jet Ranger on 12 
April, a Hiller/Soloy on 4 May, and/ or a Messerchmidt Boelkow on 22 May. 
Territories where breeding status could not be determined during the March 
helicopter flight were subsequently surveyed from the ground for signs of 
occupancy or breeding (see below for criteria). Territories containing 
breeding pairs were checked for productivity from a Bell 206 Jet Ranger on 8 
and/or 21 June. 

We attempted to ascertain the breeding status and nesting success of all 
eagle pairs. We climbed to 1 golden eagle nest to band young. Eagle pairs 
that showed no evidence of egg laying after repeated observations or after 
climbing into and examining potential nests were categorized as 
"nonbreeding . " A "breeding attempt" was confirmed if an occupied territory 
contained an incubating adult, eggs, young, or any other indication that eggs 
were laid (e.g., fresh eggshell fragments in fresh nesting material). A 
breeding attempt was "successful" if it produced 1 or more young that reached 
fledging age (i.e., 51 days for golden eagles (Steenhof 1987)). Eagle nests 
discovered after young had fledged were considered successful if: 1) a 
platform decorated this season was worn flat and contained fresh prey 



13 



LEGEND 

BIRDS OF PREY STUDY AREA 

COMPARISON AREA 

BIRDS OF PREY NATURAL AREA 




SE R HE 



Fig. 1. LOCATION OF THE BIRDS OF PREY STUDY AREA (BPSA) AND COMPARISON AREA 



remains, 2) fresh fecal matter covered the back and extended over the edge of 
the nest, and 3) no dead young birds were found within a 50-m radius of the 
nest. 

Percent of pairs breeding in 1989 and earlier years was calculated from 
preselected pairs (Steenhof and Kochert 1982). Percent of nesting attempts 
successful was based on attempts found during incubation. Nests manipulated 
by fostering , disease treatment , shade devices , etc . , were excluded from 
productivity calculations. 



RESULTS 



Nesting Density 

In 1989 golden eagle pairs occupied 30 (79%) of the 38 traditional eagle 
nesting territories in the SRBOPA. The total number of occupied territories 
in the SRBOPA was 2 less than in 1988 (Table 1). All but 2 of 29 territories 
surveyed outside the SRBOPA (Hammett GN and Malad) were occupied in 1989. Of 
the 10 vacant sites, 6 have not been occupied since 1982 or earlier. Three 
vacant sites (Strike II, Swan Dam, and PP&L 125) had been occupied by eagles 
in 1988. The Upper Sinker nesting territory was occupied after having been 
vacant in 1988. The Pump Station nesting territory was vacant for the 2nd 
consecutive year. 



Reproduction 

Golden eagle reproduction in the SRBOPA increased slightly from 1988 
levels (Table 1). Percent of pairs breeding increased from 74% in 1988 to 
80% in 1989, and percent of attempts successful increased from 55% in 1988 to 
63% in 1989. Young fledged per pair increased from 0.63 in 1988 to 0.69 in 
1989 (Table 1). As in the past 5 years, golden eagle reproduction was higher 
in the Comparison Area than in the SRBOPA (Table 2). Number of young eagles 
raised per pair in the Comparison Area decreased from 0.99 in 1988 to 0.81 in 
1989. Eighty-six percent of eagle pairs in the Comparison Area laid eggs. 
Although the percent of attempts successful in the Comparison Area (61%) was 
slightly lower than in the SRBOPA (63%), Comparison Area pairs fledged more 
young per successful attempt (1.55) than pairs in the SRBOPA ( 1 . 36 ) . 
Throughout the southwestern Idaho study area, power line nesters fared better 
than canyon nesters in 1989 (1.00 and 0.70 young fledged per pair, 
respectively; Table 2). 



ACKNOWLEDGMENTS 

Pacific Power and Light Company is acknowledged for providing flight time 
to conduct the eagle helicopter surveys. K. Troxel and P. Kochert assisted 
with golden eagle surveys. We thank R. Holman, Idaho Department of Fish and 
Game Region IV, for making observations at eagle nests in the Comparison 

Area. 



15 



Table 1. Nesting success and productivity of golden eagles in the SRBOPA, 
1971-1989. Sample sizes are in parentheses. 



Year # of % of Pairs % of # Fledged/ # Fledged Total 

Occupied Breeding Attempts Successful Per Pair # Fledged 
Territories Successful Attempt 



1971 


34 


100% 


(31) 


60% 


(20) 


1.89 


19) 


1.13 


39 


1972 


34 


— 




— 




1.64 


11) 


— 


— 


1973 


35 


65% 


(34) 


44% 


(18) 


1.37 


8) 


0.39 


14 


1974 


35 


73% 


(30) 


56% 


(18) 


1.42 


12) 


0.58 


20 


1975 


33 


75% 


(32) 


56% 


(18) 


1.43 


14) 


0.60 


20 


1976 


35 


70% 


(33) 


47% 


(15) 


1.62 


13) 


0.53 


19 


1977 


34 


82% 


(33) 


59% 


(17) 


1.53 


15) 


0.74 


25 


1978 


32 


80% 


(30) 


70% 


(10) 


1.71 


17) 


0.96 


31 


1979 


30 


97% 


(30) 


61% 


(23) 


1.53 


19) 


0.91 


27 


1980 


31 


87% 


(31) 


72% 


(18) 


1.77 


22) 


1.11 


34 


1981 


30 


100% 


(30) 


74% 


(23) 


1.73 


22) 


1.28 


38 


1982 


30 


87% 


(30) 


80% 


(25) 


1.95 


19) 


1.36 


41 


1983 


28 


96% 


(27) 


72% 


(18) 


1.56 


16)' 


1.07 


30 


1984 


31 


— 




61% 


(18) 


1.55 


11) 


0.60* 


19 


1985 


32 


39% 


(31) 


42% 


(12) 


1.00 


4) 


0.16 


5 


1986 


29 


54% 


(28) 


29% 


(14) 


1.33 


6) 


0.21 


6 


1987 


32 


78% 


(32) 


32% 


(25) 


1.38 


8) 


0.34 


11 


1988 


32 


74% 


(31) 


55% 


(22) 


1.54 


13) 


0.63 


20 


1989 


30 


80% 


(30) 


63% 


(19) 


1.36 


14) 


0.69 


21 



* based on % of pairs successful 



16 



Table 2. Nesting success and productivity of golden eagles in southwestern 
Idaho, 1989. Sample sizes are in parentheses. 



Study Area % of Pairs % of Attempts # Fledged/ # Fledged 

Breeding Successful Succ. Attempt Per Pair 



SRBOPA* 80% 63% 1.36 0.69 

(30) (19) (14) 

Comparison 86% 61% 1.55 0.81 

(22) (19) (11) 



PP&L 500 kV 100% 50% 2.00 1.00 

(4) (4) (2) 

Canyon ** 81% 62% 1.39 0.70 

(48) (34) (23) 



* includes the pair at PP&L 119. 

** includes all cliff nests in the SRBOPA and Comparison Area. 



17 



LITERATURE CITED 

Steenhof, K. 1987. Assessing raptor reproductive success and productivity. 
Pages 157-170 in B. A. Giron Pendleton, B. A. Millsap, K. W. Kline, and 
D. M. Bird, eds. Raptor Management Techniques Manual. Natl. Wildl. 
Fed. , Washington, D.C. 

Steenhof, K. , and M. N. Kochert. 1982. An evaluation of methods used to 
estimate raptor nesting success. J. Wildl. Manage. 46:885-893. 



18 



TITLE: Monitoring Long-eared Owl Occupancy in the Snake River Birds of 
Prey Area. 

INVESTIGATOR: John Doremus, Boise District, BLM 

OBJECTIVES: To locate all occupied long-eared owl territories on public 
lands in the Snake River Birds of Prey Area (SRBOPA) . 

INTRODUCTION 

The first effort to systematically locate long-eared owls (Asio otus) in 
the SRBOPA took place in 1980, when Jeffrey Marks located 64 breeding pairs 
(Marks 1980). In 1981 Marks located 41 pairs of breeding long-eared owls 
(Marks 1981). During both years Marks searched all suitable riparian habitat 
along the Snake River and its tributaries from the Indian Cove Bridge to the 
Mouth of Sinker Creek. During 1985 Doremus and Car la Schroer visited 72 
traditional long-eared owl nest sites and found 19 of the sites occupied by 1 
or more owls (Doremus and Schroer 1985). No systematic effort has been made to 
locate all occupied long-eared owls sites since 1985. In 1989 I planned to 
visit all potential long-eared owl habitat on public land in the SRBOPA. 
Conflicts in scheduling reduced the time available for the long-eared owl 
surveys. I was not able to survey all potential long-eared owl habitat in the 
SRBOPA in 1989 (Fig. 1). 



METHODS 

Riparian areas where there were sufficiently developed shrubs and trees 
were entered and searched for long-eared owls or signs of long-eared owl 
occupancy from mid-March to mid-April. Corvid nests and other structures that 
could serve as a long-eared owl nest site were observed for owls or signs of 
owl eggs, young, or feathers and down. I also looked for roost sites with 
fresh casts and fecal material. The number of passes through a riparian area 
depended on the width of the area and the density of the vegetation. A site 
was considered occupied if long-eared owls attempted to nest, behaved in a 
defensive manner, or if 1 or 2 owls were seen at a traditional site 2 or more 
times during the breeding season. 

RESULTS 

Sixty-nine of 80 traditional sites (sites found prior to 1989) were 
visited during the 1989 survey. Thirty-eight of the 69 traditional sites were 
visited frequently enough that occupancy of the site could be determined. 
Twenty- three of the 38 traditional sites were occupied by one or more owls . 
Seven new sites were located. Single birds were found at 3 traditional sites, 
but occupancy was not determined during my visit to these sites and no follow 
up visits were made. Long-eared owls were found at 8 other locations where 
they have not been found in the past. Follow up visits found no owls at two of 
these locations. There were no follow up visits at the other 6 locations. The 
density of the vegetation made complete surveys of the Barber Islands, Pump 
Draw Islands and Flat Iron Island impossible. 



19 



« Melba 



w 
o 



V, Walters Ferry 
Bridge 



^L Swan Falls Dam 



Scale 1 inch = 10 miles 
'/."/ Search Area 




Hammett 



Fig. 1. Location of long-eared owl surveys, 1989. 



Breeding attempts were observed at 20 sites. Ten pairs of owls were 
successful at fledging young, 5 pairs were unsuccessful, and nestxng success 
was not determined at the breeding sites of 5 pairs. No effort was made to 
locate successful breeding sites so it is likely that other pairs were 
successful at fledging young. 

DISCUSSION 

The temporal overlap of winter roosts and the breeding season of 
long-eared owls may lead an investigator to count winter roost stragglers as 
owls occupying a breeding site. To conduct a complete survey for long-eared 
owls in the SRBOPA it is necessary for the investigator to search all 
potential owl habitat, not just sites that have been occupied in the past. 

ACKNOWLEDGMENTS 

Marks J. S. 1980. Productivity, nest site characteristics, and food habits 
of Long-eared Owls in the Snake River Birds of Prey Study Area. Page 
36 in Snake River Birds of Prey Res. Proj. Annu. Rep. U.S. Dep. 
Inter., Bur. Land Manage., Boise, Idaho. 

Marks, J. S. 1981. Productivity, nest site characteristics, and food habits 
of Long-eared Owls in the Snake Rive Birds of Prey Study Area. Pages 
28-36 in Snake River Birds of Prey Res. Proj. Annu. Rep. U.S. Dep. 
Inter., Bur. Land Manage., Boise, Idaho. 

Doremus, J. H., and C. Schroer. 1985. Occupancy and Breeding Success of 

Long-eared Owls and Northern Harriers in the Snake River Birds of Prey 
Area. Pages 145-148 in K. Steenhof and M.N. Kochert, eds., Snake River 
Birds of Prey Res. Proj. Annu. Rep. U.S. Dep. Inter., Bur. Land 
Manage., Boise, Idaho. 



21 



TITLE: Raptor and Raven Nesting on the PP&L Malin to Midpoint 500-kV 
Transmission Line. 

INVESTIGATORS: Karen Steenhof , BLM Birds of Prey Research 

Michael N. Kochert, BLM Birds of Prey Research 
Jerry Roppe, Pacific Power & Light Company 
Mike Mulrooney, Pacific Power & Light Company 

COOPERATOR: Pacific Power and Light Company 

OBJECTIVES: 

1. To identify all occupied raptor and raven nests on the first 371 
miles of the PP&L Malin to Midpoint 500-kV transmission line. 

2. To ascertain nesting success and productivity of raptors and ravens 
nesting on the first 133 miles of the line. 

3. To ascertain nesting success and productivity of golden eagles and 
ferruginous hawks nesting on natural substrate near the intensively 
studied portion of the line for comparative purposes. 

4. To identify preferred nesting locations on the towers and to 
document how these locations relate to nesting success and possible 
contamination . 

5. To assess physiographic features that may influence use of towers by 
nesting raptors and ravens. 



INTRODUCTION 

Construction of a 500-kV transmission line across southern Idaho and 
Oregon in 1980-81 provided government and industry biologists with an 
opportunity to investigate the biology of raptors and ravens nesting on 
transmission lines. Pacific Power & Light Company (PP&L), in 
cooperation with the Bureau of Land Management (BLM), has surveyed the 500-kV 
transmission line between Midpoint (Jerome), Idaho and Malin, Oregon (Fig. 1) 
since 1981, and intensive research has been carried out since 1984. This 
report presents findings of the 6th and final year of intensive studies of 
raptor and raven nesting density and productivity on the line. 



METHODS 

Surveys were conducted in 3 study areas in 1989. The "intensive survey 
area" consisted of Miles 0-133 of the transmission line, and the "extensive 
survey area" consisted of Miles 134-371 (Fig. 1). To compare nesting success 
and productivity, golden eagles ( Aquila chrysaetos ) were surveyed in a third 
"canyon study area" extending along the Snake River and its major tributaries 
from Hagerman, Idaho to Mile 135. 



22 



to 

CO 




400 



Kilometers 



Fig. 1. Location of the Pacific Power and Light 500 kV 
transmission line. Intensive survey stretch 
is shaded. 



The entire line was surveyed from a Bell 206 Jet Ranger helicopter 
between 10 and 12 April to locate incubating pairs. Some eagle nests on 
cliffs were also checked during the April survey. Follow-up surveys of the 
entire intensive study area were conducted from a Hiller/Soloy helicopter on 
4 May and from a Messerschmidt Boelkow helicopter on 22 May. Individual 
nests in the intensive area were spot-checked from a Bell 206 Jet Ranger on 8 
and 21 June. The extensive area was re-surveyed on 23 May from a 
Messerschmidt Boelkow. Traditional golden eagle nesting territories in the 
Snake River Canyon were checked from a Hi Her Soloy on 16 March, and all were 
re-checked either from the ground or during helicopter flights in May or 
June. During all surveys helicopters were flown at speeds of 70-95 km/hr; we 
usually hovered approximately 10 m from nests for 5-25 sec to view nest 
contents. Some nests were photographed from the helicopter, and some were 
subsequently observed from the ground. 

Pairs were considered "breeding" if they laid at least 1 egg; this was 
confirmed by observing eggs, young, or an incubating adult. Because aerial 
surveys covered only the power line structures, some nonbreeding pairs could 
have been missed. We considered a breeding attempt successful if 1 or more 
young reached 80% of the average age when most young normally leave the nest. 
Nestlings were aged by comparison with photographs of known-age chicks 
(Moritsch 1983, 1985; BLM, unpubl. data). 

Data from 1984 to 1989 were reviewed to evaluate survey timing and to 
make recommendations for scheduling a single monitoring flight in future 
years. Data from each complete survey flight (1984-1989) were reviewed to 
tabulate the number of raptor and raven breeding attempts that were confirmed 
during that particular survey. Totals from each flight were then compared 
with the total number of breeding attempts identified in that particular 
year. Data were tabulated separately for the intensive survey area (Miles 
1-133) and the extensive survey area (Miles 133-371). 



RESULTS 
Nest Density and Distribution 

In 1989, 133 pairs of raptors and ravens occupied nests on the 500-kV 
transmission line. Breeding attempts were confirmed for 129 of the 133 
nesting pairs on the line. Breeding could not be confirmed at 3 occupied 
red- tailed hawk ( Buteo jamaicensis ) nests and 1 common raven ( Corvus corax) 
nest. There were no confirmed re-nesting attempts in 1989. 

Ravens were still the most numerous species nesting on the line. 
Eighty-one raven, 33 red- tailed hawk, 11 ferruginous hawk ( Buteo regalis ) , 
and 8 golden eagle pairs occupied nesting territories associated with nests 
on the line in 1989 (Table 1). The 133 occupied nesting territories 
represent the highest number of nesting pairs observed on the line since 
studies began. The total, however, is only 2 more than the previous high of 
131, recorded in 1987 and represents only a 4% increase from 1988 levels. 
Numbers of red- tailed hawk and raven pairs were the same as in 1987, their 
previously recorded high levels. Golden eagle numbers were unchanged from 
1988; ferruginous hawk pairs declined by 1; and great horned owls ( Bubo 
virginiaus ) did not nest on the line in 1989. 



24 



Table 1 . Number of occupied raptor and raven nesting territories found on the PP&L 
Malin to Midpoint 500-kV transmission line, 1981-89. 






Species 


1981 


1982 


1983 


1984 


1985 


1986 


1987 


1988 


1989 


Golden Eagle 


1 


2 


5 


4 


4 


4 


7 


8 


8 


Ferruginous Hawk 


1 


3 


9 


7 


6 


8 


9 


12 


11 


Red- tailed Hawk 





2 


2 


13 


20 


28 


33 


27 


33 


Common Raven 


1 


9 


39 


55 


58 


73 


81 


80 


81 


Great Horned Owl 




















1 


1 





TOTAL 


3 


16 


55 


79 


88 


113 


131 


128 


133 



The golden eagle pair that nested at Mile 125 in 1988 did not nest on the 
line in 1989. As in the past 2 years, the golden eagle pair at Little Canyon 
Creek (49/3) nested on one of the traditional cliff nests, approximately 400 
m from the line. A new eagle territory was established in Mile 352 in 1989. 
Eagles nested on a platform that had been used by red-tailed hawks in 1988 . 

The number of raptor and raven pairs decreased by 2 from 1988 levels in 
the intensive study area and increased by 7 in the extensive area (Table 2). 
Red-tailed hawks within the extensive area increased from 22 in 1988 to 27 in 
1989, and numbers in the intensive area increased from 5 to 6. The extensive 
area had 1 more raven pair than in 1988, and numbers in the intensive area 
were unchanged. As in past years, ferruginous hawks nested only in the 
intensive area. 

Nesting densities of all species combined were higher in the intensive 
study area (0.33 per km; 0.54 per mi) than in the extensive area (0.16 per 
km; 0.26 per mi). For the entire line, densities averaged 0.22 nests per km 
or 8 nests for every 100 towers. 

Significantly more breeding pairs occurred between Miles 59 and 127, 
within or just north of the Snake River Birds of Prey Area (SRBOPA), than in 
the remaining half of the intensive study area (X 2 = 4.63, P < 0.05). 
However, numbers of pairs near the SRBOPA decreased in 1989, while numbers in 
other parts of the intensive study area increased. As in past years, nesting 
densities were particularly high along one stretch of line within the SRBOPA 
(Miles 113-119). In 1989, this stretch contained more than 0.7 nesting pairs 
per km (1 per mile), more than 3 times the average density for the line. 



Marked Birds 

One of the golden eagles nesting on the platform at Tower 68/3 was 
wearing a blue and yellow wing marker on its right wing. The markings 
suggest that the bird was marked as a nestling at a cliff nest in or adjacent 
to the SRBOPA in 1980. This is the first sighting of a marked adult nesting 
on the transmission line. The marked bird was incubating on 4 May 1989, but 
the nesting attempt was unsuccessful. 



Nest Site Selection 

Raptors and ravens nested in all tower types on the line except the F 
type in 1989. The frequency with which the tower types were used, however, 
differed significantly from the frequency with which tower types were 
available (X z = 5.97; P < 0.05). Although A towers (Fig. 2) were the most 
commonly used towers, they were by far the most common tower type available. 
Only 7% of the A towers were used in 1989, and 16 of the 80 breeding pairs 
that nested on A towers nested on platforms and not on the tower 
latticework. In contrast, raptors and ravens nested on 30% of the available 
E towers, 11% of the C towers, and 8% of the T towers. B towers were used at 
the same rate (7%) as the A towers. The sturdier and more extensive 
latticework on the less common T and E towers (Fig. 2) may provide more 
suitable nesting substrate and therefore account for the raptors' and ravens' 
apparent preferences for them. 



26 



to 



Table 2. Number of occupied raptor and raven nesting territories found in the intensive and extensive 
study areas, 1984-89. 

Intensive E xtensive 

1984 1985 1986 1987 1988 1989 1984 1985 1986 1987 1988 1989 



Golden Eagle 


4 


4 


4: 


4* 


5* 


4* 


Ferruginous Hawk 


7 


6 





9 


12 


11 


Red-tailed Hawk 


4 


2 


4 


5 


5 


6 


Common Raven 


37 


38 


47 


53 


51 


51 


Great Horned Owl 











1 


1 







52 


50 


63 


72 


74 


72 












3 


3 


4 




















9 


18 


24 


28 


22 


27 


18 


20 


26 


28 


29 


29 




















27 


38 


50 


59 


54 


61 



* Does not include Little Canyon Creek (49/3) because the pair nested on a cliff from 1987 to 1989. 



03 





Fig. 2. Tower types used by raptors and ravens for nesting. The "E" (center) 
and "T" (right) towers were preferred over the more common "A" towers 
(left) apparently because of their sturdier and more extensive latticework. 



Red-tailed hawks used more positions on the tower for nesting than the 
other 3 diurnal species (Fig. 3). Ravens appeared to be the least versatile 
in nest site selection, nesting in the x-position in every case but one in 
1989. The x-position of the tower (Fig. 3) was the most frequently used 
position on the towers, used by 79 of 80 breeding raven pairs, 13 of 29 
red- tailed hawk pairs, 2 of 8 golden eagle pairs, and 7 of 11 ferruginous 
hawk pairs. 

More than 50% of the golden eagle and ferruginous hawk pairs nested on 
the specially designed artificial platforms that were installed at the time 
of line construction. A preference by hawks and eagles for the platforms is 
apparent because only 2% of the towers on the line contain platforms. 
Seventeen of 37 available platforms were used by breeding raptors in 1989 (6 
by golden eagles , 4 by ferruginous hawks , and 7 by red- tailed hawks ) . Nine 
of 12 platforms in the intensive area were used compared with only 8 of 25 in 
the extensive area. More platforms were used in 1989 than in any other 
single year. However, all platforms used in 1989 had been used in a previous 
year. Only 2 platforms that had been used in previous years were not used in 
1989. The Little Canyon Creek golden eagle pair nested on the cliff instead 
of on the 49/3 platform for the 3rd consecutive year. The ferruginous hawk 
pair which has nested on the 104/4 platform from 1982 to 1988 moved to the 
X-south position of the same tower in 1989. For several years, nesting 
ferruginous hawks had been bringing an unusually high number of sticks to the 
104/4 platform nest, and by 1988, the stick nest was taller than the platform 
itself. 

The 79 raven pairs that nested in the x-position showed no significant 
preference for side of tower. Forty nested on the south end of the tower, 
and 39 nested on the north side. However, 5 of 7 ferruginous hawks that 
nested in the x-position used the south side of the tower. Red-tailed hawks 
showed only a slight preference for x nests on the south side of the tower (9 
of 13 attempts in the x-position). 

Nesting Success and Productivity 

Reproductive rates of raptors in the intensive study area were generally 
higher in 1989 than in 1988. All golden eagle, ferruginous hawk, and common 
raven pairs associated with nests on the line laid eggs . Two of 4 eagle 
pairs were successful and raised 2 young each (Table 3). Percent of nesting 
attempts successful declined from 1988 levels for eagles and ravens but 
increased for ferruginous and red- tailed hawks. For each species of diurnal 
raptor, number of young fledged per pair in the intensive area was higher in 
1989 than in 1988. Number of young fledged per raven pair declined slightly 
from 1988 (Table 3). 

Wind was the only confirmed cause of nest failure in 1989. Two raven 
nests were blown from the tower between 4 May and 8 June. In addition, a 
fledged raven was found dead below its nesting tower in Mile 105. 



29 



Golden Eagle (N = 8) 



x 25 

P 75 



Ferruginous Hawks (N = 11) 



U) 


X 36 


o 






p 64 




Red-tailed Hawk (N = 29) 



C — 
x — 
p — 

w — 

D — 
B — 



— 3 

— 45 

— 24 

— 21 

— 3 

— 3 



Common Raven (N = 80) 



x 99 

D 1 



Fig. 3 Percent of raptor and raven breeding attempts in relation 
to tower position for the PP&L Malin to Midpoint 500kV 
transmission line, 1989. Sample sizes are shown in 
parentheses. Summaries do not include "T" towers. 



Table 3. Nesting success and productivity of raptors and ravens on the 
intensive survey stretch of the PP&L Malin to Midpoint 500-kV 
transmission line, 1989. 









% of 


No. 


No. 






% of 


Breeding 


Fledged 


Fledged 




No. of 


Pairs 


Attempts 


Per Succ. 


Per 




Pairs 


Breeding 


Successful 


Attempt 


Pair 


Golden Eagle 


4 


100% 


50% 


2.0 


1.0 


Ferruginous Hawk 


it 


100% 


91% 


2.6 


2.4 


Red- tailed Hawk 


6 


100%* 


100%** 


2.0 


2.0 


Common Raven 


51 


100% 


79%*** 


3.9 


3.1 



* breeding was unconfirmed for 2 pairs 

** success was unknown for 1 pair 

*** based on all nesting attempts (including re-nests) where outcome was 
known. The Mayfield (1961) estimate of nesting success was 72%. 



31 



Survey Timing 

Each year from 1985-1989, the early May survey identified the highest 
percentage (85-96%) of all known breeding attempts in the intensive survey 
area (Table 4), and the April survey identified the fewest (46-76%). Late 
May surveys were always intermediate (81-87%). In 1984, when there were no 
early May flights, a mid-May flight identified the highest percentage of 
breeding attempts (90%), a late March flight identified only 12%, and a late 
April flight identified 81%. 

When plotted as a function of time (Fig. 4), survey accuracy (as defined 
by % of total known breeding attempts confirmed) clearly peaked between 3 and 
17 May. April surveys missed a significant number of pairs that had not yet 
initiated breeding attempts. Late May surveys missed pairs that had either 
failed or already successfully fledged young. The early May surveys appeared 
to minimize both of these sources of errors. 

In the extensive area (Table 5), late May surveys always identified more 
nesting pairs (82-100%) than early April surveys (34-83%). The analysis for 
the intensive area is more meaningful because multiple surveys ensured more 
complete counts of breeding pairs. The high percentage of attempts 
identified in late May surveys of the extensive area does not necessarily 
indicate that late May surveys are more complete than early May surveys. 
Instead, it may suggest that the number of breeding attempts in the extensive 
area has been consistently underestimated because nests are missed in both 
the early April and late May surveys. 

RECOMMENDATIONS AND PLANS FOR NEXT YEAR 

We plan to prepare a manuscript for publication that summarizes 6 years 
of data collected on raptors and ravens nesting on the transmission line. 
Only one aerial survey of nesting raptors and ravens on the line is planned 
for 1990. Results suggest that early May is the optimal period to schedule a 
single survey flight, assuming that the objective of the flight is to 
identify all nesting pairs on the line. If surveys are carried out using the 
same procedures used from 1985-1989, they should be expected to identify 
85-95% of all breeding attempts on the line. Data on reproduction of golden 
eagles and ferruginous hawks nesting in the canyon will be collected as part 
of a 4-year cooperative effort to assess the effects of National Guard 
activity and habitat alteration on birds of prey. 

ACKNOWLEDGMENTS 

We thank M. Garrett and S. Wilder who assisted with data collection and 
compilation. We are also indebted to our pilots: R. McLellan, T. Miller 
(Idaho Helicopters), D. Day, (Pacificorp) , and M. Pearson (Reeder Flying 
Service ) . 



32 



Table 4. Percent of known breeding attempts identified on individual survey 
flights of the intensive survey area, 1984-1989. 



Flight # 1984 1985 1986 1987 1988 1989 

12% 54% 46% 73% 53% 76% 

first (20 March) (9 April) (9 April) (14 April) (7 April) (12 April] 

81% 90% 85% 93% 87% 96% 

second (23 April) (6 May) (6 May) (7 May) (4 May) (4 May) 

90% 85% 80% 87% 83% 81% 

third (16 May) (24 May) (27 May) (22 May) (19 May) (22 May) 



33 



CO 



120 

110 

100 

90 



580 
*70 
1 60 



£50 

LU 

ES40 

Q_ 

30 
20 
10 






80 98 99 gg 102 104 114 125 124 126 126 127137 140 142 142 144 147 



JULIRN DATE 



Figure 4. Percent of Breeding Attempts Identified on Helicopter Survey Flights 1985-1989 



Table 5. Percent of known breeding attempts identified on individual survey 
flights of the extensive survey area, 1985-1989. 



Flight # 1985 1986 1987 1988 1989 



34% 60% 74% 81% 73% 

first (8/9 April) (10 April) (13 April) (8 April) (10 April) 

100% 85% 89% 88% 92% 

second (20 May) (21 May) (21 May) (18 May) (23 May) 



35 



LITERATURE CITED 



Kochert, M. N. , K. Steenhof, J. Roppe, and M. Mulrooney. 1984. Raptor and 
raven nesting on the PP&L Malin to Midpoint 500 kV transmission line. 
Pages 20-39 in Snake River Birds of Prey Research Project Annual Report, 
1984. U.S. Dep. Inter., Bur. Land Manage., Boise, Idaho. 145pp. 



Mayfield, H. F. 1961. 
Bull. 73:255-261. 



Nesting success calculated from exposure. Wilson 



Moritsch, M. Q. 
hawks . U.S. 



1983. Photographic guide for aging nestling red-tailed 
Dep. Inter., Bur. Land Manage., Boise, Idaho. 14pp. 



hawks. 



. 1985. Photographic guide for aging nestling ferruginous 

U.S. Dep. Inter., Bur. Land Manage., Boise, Idaho. 21pp. 



Steenhof, K. , M. N. Kochert, J. Roppe, and M. Mulrooney. 1987. Raptor and 
raven nesting on the PP&L Malin to Midpoint 500 kV transmission line. 
Pages 19-33 in K. Steenhof, ed. , Snake River Birds of Prey Research 
Project Annual Report, 1987. U.S. Dep. Inter., Bur. Land Manage., Boise, 
Idaho. 159pp. 



36 



TITLE: Implications of Communal Roosting by Common Ravens to 

Operation and Maintenance of the Malin to Midpoint 500-kV 
Transmission Line. 

INVESTIGATOR: Alison L. Beck, BLM Birds of Prey Research 

COOPERATOR: Pacific Power and Light Company 

OBJECTIVES : 

1. To monitor occupancy of the Initial Point communal raven roost 
and trends in numbers of roosting ravens on the Malin to Midpoint 
500-kV transmission line. 

2. To evaluate the effectiveness of shields and pegging in 
preventing insulator contamination at the Initial Point Roost. 

INTRODUCTION 

Research to determine the implications of communal roosting by common ravens 
( Corvus cora x) to operation and maintenance of the Malin to Midpoint 500-kV 
transmission line was completed in 1987. The final research report identified 3 
monitoring objectives that were to be made part of the contamination management 
program: evaluating shields and pegging, monitoring contamination, and 
determining locations and causes of outages. 

In May 1989, shields and pegging were installed on 24 towers at the Initial 
Point roost, between miles 107 and 112. Contamination estimates were conducted 
immediately after installation and washing of insulators and again 5 months 
later. The roost was monitored for occupancy and trends in numbers of roosting 
ravens from the first date of installation until 1 November. This report 
presents the results of the 1989 monitoring effort. 

METHODS 

Fiberglass shields and plastic pegging were installed on 24 towers at the 
Initial Point roost, from tower 2/107 to 4/112. Tower 1/110, a turn ("E") 
tower, was excluded because it was not vulnerable to contamination (Young and 
Engel 1988a). Shields and their installation are described by Young and Engel 
(1988a). Pegging consisted of 0.95-cm (3/8-in) plastic tubing, cut in 30-cm 
(12-in) lengths and glued into holes drilled in 5-cm (2-in) PVC pipe. Each 
piece of PVC pipe was fitted with 36 pegs, 2 attached to the outer half of north 
and south C sections on all treated towers with wire. Installation began on 21 
May and was completed on 24 May. Insulators were washed at the time of 
installation at towers with contamination determined to be severe by the line 
patrolman (M. Mulrooney, pers commun. ) . Insulator strings on towers 111/4, 
112/1, and 112/2 were treated by washing. 

Contamination estimates were made at each tower fitted with shields and 
pegging on the day following completion of installation. Estimates were made 
according to procedures described by Young and Engel (1988a). Estimates were 



37 



made daily from 22 to 25 May. Contamination estimates were not made for towers 
110/2 and 110/3 where insulators are made of an opaque ceramic material. Cloud 
cover ranged from 10% to 90% on days when contamination estimates were conducted 
in May. Contamination was scored for the same 22 towers 5 months later, on 1 
November. Cloud cover was 0% at that time. Estimates were made for all 6 
insulator strings at every tower. Individual bell scores for the 2 center phase 
and for each of the outermost strings (directly under pegging on C sections) 
were used for analysis. Two-sample median tests were used to determine whether 
shields and pegging are effective in preventing insulator contamination (Young 
and Engel 1988a) . 

At the time of the final contamination estimates, shields and pegging were 
visually inspected from the ground for damage. 

Evening observations of roosting ravens began on 22 May and were conducted 
nightly until 29 May. Beginning 6 June, Tuesday evening observations were done 
biweekly until 1 November. The counts were done from an observation point 
approximately 500 m south of the transmission line. The 24 treated towers were 
monitored from 30 min before sunset until it was too dark to accurately count 
ravens, usually 30 min after sunset. Every 10 min, an observer with a spotting 
scope counted the number of ravens on each tower section (Young and Engel 
1988a: Fig. 3-1). The highest total number of ravens counted during a 10-min 
interval was considered the night's count for the roost. 

Pacific Power and Light Company monitored for line trips and outages. 

RESULTS 



Occupancy of Roost and Numbers of Roosting Ravens 

Twenty of the 24 treated towers were occupied by roosting ravens during the 
study period. No roosting birds were observed at either the extreme western 
(112/4 and 112/3) or eastern (107/2 and 107/3) ends of the roost. In May and 
June, towers 111/3 through 112/2 were most frequently used. From early June 
through September, birds occupied the center portion of the roost, from 108/2 to 
111/1. Use of towers was restricted to the area from 109/3 to 111/2 in late 
September and October. The maximum number of evenings any 1 tower was observed 
to be occupied through the study period was 9. In the early part of the study 
period, tower 112/1 was occupied by roosting ravens on 9 of 11 evenings 
observation. Tower 110/3 was occupied during each of 9 evening observations 
from 11 July to 1 November. 

Maximum numbers of roosting ravens were highest from July through October 
(Fig. 1). Approximately 100 birds were counted at the roost in May and June 
(mean = 103.00 ± 91.33). The mean maximum count from 11 July through 3 October 
was 556 (± 107.8). Numbers of ravens observed on 17 October and 1 November were 
59 and 113. The highest maximum count was 675 on 5 September. 



38 



700 



00 

C 



r 



© 

E 

15 




Julian Date 



Fig. 1 . Numbers of roosting ravens, Initial Point roost, 1 989. 



39 



Effectiveness of Shields and Pegging 

Immediate Response of Ravens 

Installation of shields and pegging took place over a period of 5 days, with 
2 crews working from opposite ends of the roost toward the middle. Throughout 
the period, towers 111/4, 112/1 and 112/2 were used by roosting ravens. On 22 
May, towers 112/1 and 112/2 were treated, ravens occupied them that evening 
without apparent hesitation. The following day, 111/4 was among the towers 
treated; it was occupied that evening. 

Use of Towers 

Ravens roosted on 20 of the 24 treated towers. None of the towers east or 
west of the treated segment and visible from the observation point were occupied 
during the study period. Tower 110/1, the only untreated tower of the Initial 
Point roost, was consistently used by roosting ravens after the end of July. 

Distribution of Ravens Among Tower Sections 

Significantly fewer ravens roosted above insulators during the week of 
installation and the first 3 weeks following installation than after that period 
(1-way ANOVA, F = 11.585, df = 2, P < 0.01) (Table 1). During installation and 
the 3 weeks following, more ravens used the D sections than any other, while 
after that time the B section was most heavily occupied. Throughout the study 
period, fewer than 10% of roosting ravens occupied the C sections. Birds were 
not observed roosting on the portions of C sections fitted with pegging. Ravens 
occupied the inner half of the C section, and on 2 occasions the horizontal bar 
below the pegging. Even where individual pegs were lost from C sections, ravens 
did not roost in the resulting gaps. 

Use of tower sections during the period after 3 weeks following installation 
in 1989 differed from use at the Initial Point Roost in 1984 and 1985 (Young and 
Engel 1988a). The proportion of birds roosting above insulators was slightly 
higher in years prior to installation (82%) than in 1989 (78.9%). Use of C 
sections was lower in 1989 (8.4%, n = 330) than in previous years (23%, n - 
17,846). More ravens roosted on X and A sections and on A wires in 1989 than 
reported for 1984 and 1985. 

Contaminat i on 

Contamination estimates were made for 22 treated towers in May, immediately 
following treatment and washing, and again 5 months later in November (Table 
2). Towers 110/3 and 110/4 have opaque porcelain insulators and were not scored 
for contamination. Scores for the 2 innermost insulator strings and for the 2 
outermost strings for May and November were compared. Calculated Spearman rank 
coefficient resulted in an r value of 0.362, indicating no significant 
correlation between changes in contamination scores and number of tower nights 
of occupancy (P > 0.05). 



40 



Table 1. Distribution of roosting ravens among tower sections at the Initial Point roost during 1984 and 1985, 
during and 3 weeks following installation of shields and pegging (22 May-27 June 1989) and after 3 
weeks following installation (11 July-1 November 1989). 



£» 



Period 


No . tower- 


Above 








Tower Sections 










evenings 


insulators 
























C 


X 


A 


AW 


B 


D 


W 


E 


1984, 1985« 




75948 


17846 


25» 




3017 


22959 


11382 


460 


1559 






82.0% 


23.0% 


25.0% 




4.0% 


30.0% 


15.0% 


1.0% 


2.0% 


Installation and 


19 


1235 


97 


108 


216 


84 


261 


390 


37 


42 


3 weeks following 




62.0% 


7.9% 


8.7% 


17.5% 


6.8% 


21.1% 


31.6% 


3.0% 


3.4% 


After first 


68 


4085 


330 


248 


978 


413 


1289 


698 


84 


45 


3 weeks 




78.9% 


8.4% 


6.3% 


24.9% 


10.5% 


32.9% 


17.8% 


2.1% 


1.1% 



« Young and Engel 1988 

b sections A and X combined 



Table 2. Use of towers and contamination trends at the Initial Point Roost following installation 
of shields and pegging, 22 May - 1 November, 1989. 



Mean number of ravens/night 
Tower Above insulators On C Sections (n) 



Contamination trend (May-November) 
Center Insulators Cuter insulators 





107/2 


















N 


b 












N 


b 














107/3 


















D 


(x 


- 


6.617, 


P 


< 


0.05) 


N 


(x 


= 


0.543, 


P 


> 


0.05) 




107/4 


















N 


(x 


■- 


0.332, 


P 


> 


0.05) 


I 


(x 


= 


6.382, 


P 


< 


0.05) 




108/1 


24.50 


+ 


0.50 


0.50 


-:• 


0.50 


(1) 


N 


{x 


- 


1.010, 


P 


> 


0.05) 


N 


(x 


- 


1.010, 


P 


> 


0.05) 




108/3 


49.00 


+ 


26.52 


7.00 


+ 


9.30 


(4) 


N 


b 












N 


b 














108/4 


35.25 


•:• 


20.84 


6.50 


+ 


7.37 


(4) 


N 


b 












N 


b 














108/5 


63.00 


+ 


17.01 


18.25 


■!- 


12.52 


(4) 


I 


(x 


- 


7.526, 


P 


< 


0.05) 


I 


(x 


- 


7.562, 


P 


< 


0.05) 




109/1 


18.00 


-!• 


7.00 









(2) 


D 


(x 


= 


5.827, 


P 


< 


0.05) 


N 


(x 


~ 


2.040, 


P 


> 


0.05) 


,fc> 


109/2 


38.50 


+ 


10.01 


5.00 


+ 


0.71 


(4) 


N 


(x 


= 


0.378, 


P 


> 


0.05) 


N 


b 












M 


109/3 


54.57 


+ 


35.80 


7.14 


+ 


5.25 


!7) 


N 


(x 


- 


2.777, 


P 


> 


0.05) 


N 


(X 


- 


3.092, 


P 


> 


0.05) 




109/4 


65.67 


+ 


14.51 


13.83 


+ 


9.25 


16) 


I 


(x 


- 


100.0, 


P 


< 


0.05) 


I 


(x 


- 


72.41, 


P 


< 


0.05) 




110/2 


27.20 


+ 


14.22 









5) 


N 


(x 


- 


2.040, 


P 


> 


0.05) 


N 


(x 


- 


2.343, 


P 


> 


0.05) 




110/3 


41.89 


+ 


18.86 


0.22 


+ 


0.42 


'9) 




c 














c 














110/4 


52.86 


-!- 


23.28 


1.00 


+ 


1.69 


7) 




c 














c 














110/5 


64.00 


+ 


27.311 


1.80 


+ 


2.23 


5) 


N 


(x 


~ 


3.368, 


P 


> 


0.05) 


N 


(X 


~ 


0.440, 


P 


> 


0.05) 




111/1 


26.60 


-:- 


28.67 


0.20 


+ 


0.40 


5) 


N 


b 












I 


(x 


X 


21.76, 


P 


< 


0.05) 




111/2 


11.50 


+ 


5.50 









2) 


N 


(x 


~ 


1.214, 


P 


> 


0.05) 


N 


b 














111/3 


2.00 


+ 


1.00 









2) 


I 


(x 


- 


45.01, 


P 


< 


0.05) 


N 


<x 


= 


0.543, 


P 


> 


0.05) 




111/4 


67.33 


+ 


21.31 


11.33 


+ 


7.36 1 


3) 


I 


(x 


= 


15.85, 


P 


< 


0.05) 


N 


(X 


= 


3.092, 


P 


> 


0.05) 




112/1 


43.11 


+ 


19.15 


5.55 


+ 


7.37 


9) 


N 


(x 


- 


0.584, 


P 


> 


0.05) 


N 


(X 


™ 


1.000, 


P 


> 


0.05) 




112/2 


42.66 


-)■ 


54.74 


4.33 


+ 


6.13 < 


3) 


I 


(x 


~ 


7.428, 


P 


< 


0.05) 


N 


b 














112/3 


















D 


(x 


= 


11.96, 


P 


< 


0.05) 


N 


b 














112/4 


















D 


(x 




8.695, 


P 


< 


0.05) 


D 


(x 


~- 


14.94, 


P 


< 


0.05) 



D = significant decrease, I = significant increase, N = no significant change 
b = all insulator scores equivalent, test statistic could not be calculated 
c = porcelain insulators, contamination could not be estimated 



At 3 towers, decreases in contamination were observed for center insulator 
strings (107/3, 109/1, 112/3). Contamination of both center and outer insulator 
strings decreased at tower 112/4. All but one of those towers were not used by 
ravens throughout the study period. Tower 109/1 was occupied on 2 evenings of 
observation; no ravens roosted on the tower's C sections. There were increases 
in contamination at 8 towers, 3 showed increases only on the center strings 
(111/3, 111/4, 112/2), 3 on outermost strings only (107/4, 108/2, 111/1). 
Increased contamination was shown on both center and outermost strings for 2 
towers (108/5, 109/4). Towers showing increased contamination were occupied on 
from to 6 nights observations. Towers showing overall increase were occupied 
on 4 (108/5) and 6 (109/4) evenings. There was no significant difference 
between contamination scores for May and November for the remaining 10 towers. 
Evenings of observed use of those towers ranged from to 9. 



Durability of Shields and Pegging 

At the time of contamination estimation each tower was checked for broken 
and missing pegs. Each tower had been fitted with 4 sets of 36 pegs, total of 
144 per tower. Twenty-one towers had from 1 to 13 missing or broken pegs (mean 
= 2.7). 



Outages 

No outages were reported by Pacific Power and Light during the 1989 study 
period. 



DISCUSSION 

Maximum numbers of roosting ravens were lower in 1989 than in previous 
years. The peak count of 2,103 ravens in 1984 is more than 3 times the highest 
count for 1989. Coordinated roost watches were not conducted in 1989, so it 
cannot be determined whether overall numbers are lower or whether alternate 
roosts are being used more heavily. 

Patterns of roost use over a period of months are similar for 1989 and 
previous years. There is a general trend of increasing maximum count beginning 
in early summer, with a decrease beginning in late September. The date of the 
highest maximum count was slightly later in 1989 than in previous years. From 
1984 to 1987, maximum numbers of roosting ravens were observed between mid-July 
and mid-August. In 1989, the highest maximum count occurred on 5 September. 

Without 1989 data for roost use prior to installation of shields and 
pegging, assessment of raven response to treatment of roost towers is limited. 
The birds' use of 2 towers on the day of treatment indicates that, as previously 
observed, raven response to installation is negligible. Significantly more 
birds roosted below the insulators during the time of installation and the 3 
weeks following than in previous years or in the latter part of the 1989 
season. This pattern changed after that time. Young and Engel (1988b) 
documented a change in use of tower sections associated with installation of 
shields and pegging at the Marsing Southwest Roost in 1988. Prior to and after 
installation, ravens were more likely to roost above insulators, but in the time 



43 



immediately following installation, more birds roosted below the insulators. 
This year's data seem to corroborate previous years' findings that ravens are 
more likely to roost below insulators around the time of installation of shields 
and pegging. 

Changes in contamination over the study period show no clear patterns. 
There was no strong correlation between changes in contamination levels and 
frequency of use by roosting ravens. Of 4 towers showing decreases in 
contamination, all but 1 were not observed to have been occupied during the 
study period. Tower 109/1 showed decreased contamination of the center 
insulator strings and was occupied twice during the observation period. Numbers 
of ravens roosting on 109/1 were relatively low (mean = 18 ± 7). These results 
indicate that over time, existing contamination may decrease on insulators that 
are protected from further contamination. Not all towers that were not observed 
to be occupied during the period showed decreasing contamination, however. One 
(107/4) showed an increase in contamination of the outermost strings; another 
(107/2) showed no change. 

Increases in contamination were observed for 8 towers, 6 on either the 
center or outermost strings of insulators, 2 on both. Included were towers 
never observed occupied by roosting ravens (107/4), one used twice (111/3), 3 
used 3 times (108/2, 111/4, 112/2), and one used 5 times (111/1). Of the 2 
towers which showed increased contamination on both center and outer insulator 
strings, one was occupied 4 times (108/5) and one 6 times (109/4). Towers 
showing no change in contamination also varied in the number nights they were 
observed occupied by roosting ravens, ranging from to 9. 

The inconsistent patterns of levels of tower use and contamination changes 
may indicate that towers could have been occupied during the study period, on 
evenings when no observation was conducted. Further, varying light conditions 
may be a complicating factor in estimating contamination. Estimations in May 
were conducted on the days following installation of shields and pegging and 
cloud cover ranged from 10% to 90% over the period of 4 days. End of the season 
estimates were all done 1 November when cloud cover was 0%. This may have 
affected consistency in scoring contamination of insulators. Observer 
inconsistency is also a possible factor, though this was minimized by having the 
same observer do all scoring. 

While not quantified, levels of contamination on shields is important to 
note. Throughout the study period, accumulations of waste on shields increased 
visibly. In November when insulator contamination was estimated, extremely high 
levels of accumulated waste were observed on shields on towers which were most 
frequently used for roosting. This indicates that, if the shields had been 
absent, insulator contamination might have been greater. 

Visual counts of pegs at each tower showed an average of 2.7 pegs missing or 
broken from an original total of 144. Pieces of pegging were collected below 
several towers. All pieces had one unevenly broken end, suggesting that they 
had been broken off. Most appeared from the ground to have broken off at the 
point of attachment to the PVC pipe, though at 3 towers pegs were only partially 
broken off. The 36-peg units of PVC appeared to have remained securely in place 
throughout the study period. The materials and attachment methods used at 
Initial Point in 1989 were developed in response to problems at the Wilson Creek 



44 



iMBur—"""™*"™ 



roost. There, plastic material used to attach lengths of pegging deteriorated, 
and strips of pegging were lost (L. Young, pers commun.). Five months after 
installation, no such problem had occurred at the Initial Point roost. 

No problems were observed with shields during the study period. Attachments 
appear to be secure, gaps between shields are minimal. Observations during 
heavy winds showed no indication of instability of shields. 

Patterns of raven occupancy of towers indicates that a sufficient number of 
towers were treated at the Initial Point roost. 

MANAGEMENT RECOMMENDATIONS 
Results of 1989 monitoring give rise to the following recommendations: 

1 . Communal raven roosts should continue to be monitored in order to 
determine what other areas should be treated with shields and pegging. Monthly 
coordinated roost observations in 1990 at the 5 major roosts identified by Young 
and Engel (1988a) would permit assessment of use of roosts. During annual line 
surveys conducted by Pacific Power and Light Company contamination should be 
noted. Evening observations of possible new roosts may be done on an as 
recommended basis. Occurrences of outages may also provide opportunities to 
identify roost sites vulnerable to high levels of contamination by roosting 
ravens as possible candidates for application of shields and pegging. 

2. Pegging material used this year should be observed further. Its 
ability to withstand cold temperatures, as well as its durability over a period 
of months and years should be evaluated. The low level of loss and breakage 
indicates that the materials and attachment methods used at Initial Point may be 
more effective than other treatments. 

3. Durability of shields over time should be checked. As of November, the 
fiberglass and installation method both appeared to be in good condition. An 
effort was made to minimize the widths of gaps between shield on individual 
towers. Similar efforts should be made in future installation efforts. 

4. Effectiveness of shields and pegging at preventing accumulation of 
contamination, and, ultimately, power outages should be evaluated over a period 
of years. This should include monitoring contamination at treated roosts during 
annual line surveys and investigation of causes of line trips and outages. 

5. Long-term evaluation of numbers of roosting ravens would provide 
information about fluctuations in raven populations and roost site use over a 
period of years. A solid base of data has been built since this study began in 
1984, and with continued low-level monitoring, important information about 
long-range population trends could be gained. 

A<3KN0WLEDGMENTS 

Leonard Young, Mike Kochert, and Karen Steenhof provided guidance for the 
1989 monitoring effort. Support and logistical assistance from Mike Mulrooney, 
Monte Garrett, and Jerry Roppe are greatly appreciated. Pat Haas was an 



45 



invaluable field assistant throughout the study period. Roost observations were 
conducted by Eric Atkinson, Dave Beig, and Dawn McAnnis in the early part of the 
season. This work was conducted under BLM contract No. ID-010-PH9-093. 



LITERATURE CITED 

Young, L. S. and K. A. Engel. 1988a. Implications of communal roosting by 
coiranon ravens to operation and maintenance of Pacific Power and Light 
Company's Malin to Midpoint 500-kV transmission line. Pacific Power and 
Light Co., Portland, Oreg. 154pp. 

Young, L. S. and K. A. Engel. 1988b. Implications of communal roosting by 
common ravens to operation and maintenance of Pacific Power and Light 
Company's Malin to Midpoint 500-kV transmission line. 1988 Annual Report. 
Pacific Power and Light Co., Portland, Oreg. 13pp. 



46 



TITLE: Use of Nest Boxes by American Kestrels in Southwestern Idaho. 

INVESTIGATORS: Karen Steenhof , BUI Birds of Prey Research 

CO0PERAT0RS: Idaho Department of Fish and Game, Nongame Program 
Idaho Department of Transportation 

OBJECTIVES : 

1. Determine kestrel occupancy rates and nesting success at boxes 
erected in southwestern Idaho. 

2. Mark nestling and adult kestrels to accumulate baseline data for 
future studies on dispersal and population dynamics. 

INTRODUCTION 

This study began in 1985 when nest boxes were erected on abandoned power 
poles in the Snake River Birds of Prey Area in an effort to learn more about 
the food habits and breeding biology of American kestrels ( Falco sparverius ) 
in southwestern Idaho (Steenhof et al. 1985). The limited use of those boxes 
prompted curiosity about factors that influence occupancy rates. In 1986, 
the Idaho Fish and Game Department's Nongame program joined the study, and 
the study area expanded to include agricultural and suburban habitat in the 
Kuna area as well as Interstate 84 between Simco Road and Caldwell. 

METHODS 

In 1989, 69 boxes were available to kestrels for nesting in the 
southwestern Idaho study area. Seven boxes had fallen, deteriorated, or been 
vandalized since the nesting season of 1988. An eighth box was destroyed 
after a kestrel had fledged from the box in 1989. Of the 69 boxes available, 
30 were on trees within agricultural habitat in the vicinity of Kuna, Idaho 
(hereafter referred to as the Kuna Route), 29 were on highway signs along 
Interstate 84 between Simco Road and Caldwell (hereafter referred to as the 
1-84 Route), and 10 were on abandoned power poles along the north rim of the 
Snake River Canyon (hereafter referred to as the BOPA route). 

Each box on the Kuna and 1-84 route was checked at least twice during the 
nesting season. The BOPA boxes were checked only once. Nest checks began in 
April and continued through July, with all boxes being checked at least once 
between 15 May and 15 June. All boxes with viable nesting attempts were 
re-visited as necessary to band young and ascertain nesting success. Nests 
with young that were 75% feathered were considered successful. Investigators 
checked boxes from a ladder or while standing on a vehicle. When checking 
boxes, investigators inserted a hole stuff er into the nest box entrance to 
trap any adult birds in the box. Adults and young were weighed with a 300 g 
Pesola balance. Kestrel eggs that did not hatch after the normal period of 
incubation were collected, stored in a refrigerator, and transferred to 
Lowell McEwen (Colorado State University) for chemical analysis. Nests of 
European starlings (Sturnus vulgaris ) were removed in an effort to keep all 
boxes suitable for kestrel nesting. 

47 



RESULTS 

Sixteen of the 69 boxes (23%) were used for nesting by kestrels in 1989. 
In addition, kestrel pairs exhibited defensive behavior in the vicinity of 2 
other boxes (Kuna #5 and Kuna #15) and were probably nesting in nearby tree 
cavities. The 1989 box occupancy rate was lower than the rates observed in 
1987 and 1988 (30% and 28%, respectively). Occupancy rates on the 1-84 and 
Kuna routes were similar (28% and 27%). Eight of the occupied boxes were on 
the Kuna route, and 8 were on the 1-84 route. No kestrels nested on the BOPA 
route in 1989. 

Three boxes were used by kestrels for the first time in 1989. Ten of the 
boxes used by kestrels had been used in 1988, and 3 were last used in 1987. 

Overall nesting success of 16 kestrel pairs in 1989 was 50%, the same as 
that of 22 pairs studied in 1988 (Steenhof and Groves 1988). However, 
success rates on the Kuna route in 1989 (75%) were significantly higher (X 2 
= 4.0, P >0.05) than rates on the 1-84 route (25%). In the past 2 years, 
success rates have been similar on the 2 routes (Steenhof and Groves 1987, 
1988), and in 1986 success rates were higher on the 1-84 route (Steenhof et 
al. 1986). 

Clutch sizes ranged from 4 to 6 in 1989. This was the first year that a 
clutch of 6 had been observed in this area. All 6 young fledged from 1 of 
the 2 nests with 6 eggs. Overall, brood size at fledging ranged from 1 to 6 
and averaged 3.38 (n = 8). Five of the 8 successful nests experienced some 
loss of eggs or nestlings. Investigator disturbance was responsible for at 
least 4 egg losses at 3 nests and 1 nestling loss at another nest. Two young 
at Kuna Box #106 reached fledging age but did not survive because of physical 
deformities. The male and female siblings (the only 2 young known to have 
hatched from a clutch of 5) had severely splayed feet. The bone deformities 
were first observed when the young were 14 days of age. 

I banded 32 kestrels in 1989 (24 nestlings and 8 adults). Of the adults 
banded, 4 were females, and 4 were males. On 18 May, I captured a banded 
female in a box with 5 eggs. This bird had been banded as an adult on 22 
January 1988 by Ted Swem within 8 km of Kuna. It was nesting in a box that 
had never been used previously. All 4 males were captured in boxes where 
males had never been previously caught. However, 3 of the 5 females were 
from boxes where different females had been captured in either 1988 (n =2) or 
1987 (n = 1). These findings, along with similar findings in 1988, suggest 
that kestrel nest site fidelity is low in this study area. 

Starling eggs or young were found in 29 of the 69 boxes, and house 
sparrow ( Passer domesticus ) eggs were found in 1 box. Unidentified nest 
material was found in an additional 11 boxes. Starling occupancy rates were 
highest along the 1-84 route (62%). House sparrows also nested in the space 
between the nest box and the highway sign at 1-84 #7. A deer mouse 
( Peromyscus maniculatus ) was found in 1 of the BOPA boxes. Twelve boxes had 
no confirmed use by any species during the nesting season. One box was used 
by both kestrels and starlings; kestrels nested in a box that had starling 
eggs on 20 April. 



48 



Weights of adult females ranged from 119 to 151 g and averaged 135 g (n : 
5; s.d. = 13). The lightest female was captured while brooding small young; 
the lightest incubating female weighed 127 g. Weights of adult males ranged 
from 99 to 115 g and averaged 110 g (n = 4; s.d. = 8). 



ACKNOWLEDGMENTS 

This year's study would not have been possible without the assistance of 
several volunteers who accompanied me on nest checks. I would like to thank 
M. Luque, L. Langelier, M. McCoy, W. Heck, D. Parrish, A. Okamoto, B. Rose, 
and B. Tripp, for their assistance. The National Geographic Society donated 
a ladder to the study. We are especially indebted to the landowners in the 
Kuna area who graciously allowed us to set up and check boxes on their 
property. 



LITERATURE CITED 

Steenhof, K. , D. Ramirez, and J. Doremus. 1985. Use of nest boxes by 

American kestrels in the Snake River Birds of Prey Area. Pages 138-144 
in K. Steenhof and M.N. Kochert, eds. Snake River Birds of Prey Research 
Pro j . Annu. Rep., Bur. Land Manage. Boise, Idaho. 

Steenhof, K. , C. Groves, and D. Ramirez. 1986. Use of nest boxes by 

American kestrels in Southwestern Idaho. Pages 130-132 in K. Steenhof 
and M.N. Kochert, eds. Snake River Birds of Prey Research Proj. Annu. 
Rep., Bur. Land Manage. Boise, Idaho. 

Steenhof, K. , and C. Groves. 1987. Use of nest boxes by American kestrels 
in Southwestern Idaho. Pages 94-97 in K. Steenhof, ed. Snake River Birds 
of Prey Research Proj. Annu. Rep., Bur. Land Manage. Boise, Idaho. 

Steenhof, K. , and C. Groves. 1988. Use of nest boxes by American kestrels 
in Southwestern Idaho. Pages 53-55 in K. Steenhof, ed. Snake River Birds 
of Prey Research Proj. Annu. Rep., Bur. Land Manage. Boise, Idaho. 



49 



TITLE: Feeding Ecology of the Barn Owl in the Snake River Birds of Prey 
Area, 

INVESTIGATOR: Carl D. Marti, Department of Zoology, Weber State College 

COOPERATOR: Weber State College 

OBJECTIVES : 

1. Determine food habits and other food niche parameters of 
nesting barn owls ( Tyto alba ) . 

2. Determine food niche variation (a) among sites and (b) 
among years. 

3. Determine the barn owl's position in the raptor feeding 
guild. 

INTRODUCTION 

Field studies for this project began in 1978 and have continued through 
1989. All data reported here were obtained in the Snake River Birds of Prey 
Area (SRBOPA) which is described in U.S. Dep. Inter. (1979). Analysis and 
subsequent statistical treatments were done at Weber State College, Ogden, 
Utah. Reports on previous years are also available (Marti 1979, 1981, 1982, 
1983, 1984, 1985, 1986, 1987, 1988). 

This report summarizes field activities and preliminary analysis for 1989 
data. An index to trends in barn owl numbers in the SRBOPA is continued from 
previous years . 

ANNUAL REPORT 

I made only one collecting visit (26-28 April) to the SRBOPA in 1989 
because low barn owl densities did not warrant further visits. I collected two 
samples of regurgitated pellets from 2 sites (Table 1). Two additional samples 
of pellets were collected from Upper Lower Black Butte by Helen Ulmschneider. 
A summary of the prey content of these pellets is in Table 2. 

Dietary frequencies of major prey changed little from 1988. The dominant 
prey species, Microtus montanus , declined slightly from the previous year. 
Birds showed the greatest change in dietary composition from 1988 to 1989 
increasing from 1.3 to 4.8%. 

The apparent decline in number of nesting barn owls beginning in 1986 
continued in 1989. Only two of 15 traditional nest sites were occupied and 
nesting was not verified at either. Data from 1989 are compared with other 
years in Table 3. Three traditional barn owl nest sites were occupied by other 
species: prairie falcon ( Falco mexicanus ) , great horned owl ( Bubo virginianus ) 
and woodrat ( Neotoma sp. ) . 



50 



Table 1. Collection sites for barn owl food habits data in the 
SRBOPA, 1989. 



Lower Lower Black Butte 
Upper Lower Black Butte 



Table 2. Total prey identified for the barn owl in the SRBOPA, 
1989. 







Percent 


Prey species 


Number 


number 


MAMMALS 






Sorex vagrans 


i 


0.2 


Mus musculus 


46 


7.2 


Peromyscus spp. 


64 


10.0 


Reithrodontomys megalotis 


29 


4.5 


Microtus montanus 


307 


48.0 


Neotoma lepida 


2 


0.3 


Perognathus parvus 


60 


9.4 


Dipodomys ordii 


45 


7.0 


Thomorays townsendii (juvenile) 


53 


8.3 


unidentified leporid (neonate) 


1 


0.2 


BIRDS 






Sturnus vulgaris 


1 


0.2 


unidentified icterid 


3 


0.5 


unidentified medium bird 


3 


0.5 


unidentified small bird 


23 


3.6 



ARTHROPODS 

unidentified scorpion 1 0-2 



Totals 639 100 



51 



Table 3. Comparison of pellet collection data from nest sites of barn owls in 
the SRBOPA. 



Year of collection 



1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 



Number of occupied 

sit es 15 13 25 16 16 19 15 5 4 7 2 

Number of pellet 

collections 33 18 38 22 28 33 26 11 8 18 4 

Total number of 

prey identified 5426 3326 5359 5074 4142 7475 5559 996 1451 3552 639 

Number annual 

collecting visits 3332333223s 



52 



PLANS FOR 1990 



Three trips to the SRBOPA are planned for the spring/ summer of 1990. The 
goals for 1990 are to continue collecting food habits data for the analysis of 
long-term predation trends by barn owls and to monitor trends in breeding numbers, 



ACKMOWLEDGMENTS 



I thank Michael Kochert, Karen Steenhof , John Doremus, Jeff Marks, Lenny Young 
and all of the Snake River Birds of Prey Research staff for a variety of 
assistance in carrying out this study. The assistance of Helen Ulmschneider in 
making two collections of pellets is appreciated. The Bureau of Land Management 
provided a vehicle for field use and living space in field camps. Weber State 
College provided a Faculty Research Grant covering travel to the study area from 
Ogden, Utah, and laboratory space and computer facilities for data analysis. 



LITERATURE CITED 

Marti, CD. 1979. Ecology of nesting barn owls in the Snake River Birds of 
Prey Area. Pages 32-37 in Snake River Birds of Prey Res. Proj. Annu. Rep. 
U.S. Dep. Inter., Bur. Land Manage., Boise, Idaho. 

Marti, CD. 1981. Feeding ecology of the barn owl in the Snake River Birds 

of Prey Area. Pages 37-40 in Snake River Birds of Prey Res. Proj. Annu. Rep. 
U.S. Dep. Inter., Bur. Land Manage., Boise, Idaho. 

Marti, CD. 1982. Feeding ecology of the barn owl in the Snake River Birds 
of Prey Area. Pages 39-42 in Snake River Birds of Prey Res. Proj. Annu. 
Rep. U.S. Dep. Inter., Bur. Land Manage., Boise, Idaho. 

Marti, C D. 1983. Feeding ecology of the common barn owl in the Snake River 

Birds of Prey Area. Pages 53-55 in Snake River Birds of Prey Res. Proj. Annu. 
Rep. U.S. Dep. Inter., Bur. Land Manage., Boise, Idaho. 

Marti, C D. 1984. Feeding ecology of the common barn owl in the Snake River 
Birds of Prey Area. Pages 121-123 in Snake River Birds of Prey Res. Proj. 
Annu Rep. U.S. Dep. Inter., Bur. Land Manage., Boise, Idaho. 

Marti, C D. 1985. Feeding ecology of the common barn owl in the Snake River 
Birds of Prey Area. Pages 131-134 in Snake River Birds of Prey Res. Proj. 
Annu. Rep. U.S. Dep. Inter., Bur. Land Manage., Boise, Idaho. 

Marti, C D. 1986. Feeding ecology of the common barn owl in the Snake River 
Birds of Prey Area. Pages 123-126 in Snake River Birds of Prey Res. Proj. 
Annu. Rep. U.S. Dep. Inter., Bur. Land Manage. , Boise Idaho. 

Marti, C D. 1987. Feeding ecology of the common barn owl in the Snake River 
Birds of Prey Area. Pages 101-105 in Snake River Birds of Prey Res. Proj. 
Annu. Rep. U.S. Dep. Inter., Bur. Land Manage., Boise, Idaho. 



53 



Marti, C. D. 1988. Feeding ecology of the common barn owl in the Snake River 

Birds of Prey Area. Pages 56-61 in Snake River Birds of Prey Res. Proj. Annu. 
Rep. U.S. Dep. Inter., Bur. Land Manage., Boise, Idaho. 

U.S. D.I. 1979. Snake River Birds of Prey Special Research Report. Bur. Land 
Manage., Boise Distr., Boise, Idaho. 



54 



TITLE: Nest Box Use, Reproduction, Movement, Food Habits, 

and Annual Cycle of Body Mass of Western Screech-Owls 
in the Snake River Birds of Prey Area. 



INVESTIGATORS: Jeffrey Marks, University of Montana, Missoula, Montana 
John Doremus, BLM Bruneau Resource Area 

OBJECTIVES: To determine patterns of nest box use, fidelity to site and 

mate, reproductive success, and the annual cycle of body mass 
in Western Screech-Owls (Otus kennicotti ) . 



METHODS 

Nest box locations available for roosting/reproduction of western screech 
owls in 1989 are the same as in 1988 (Table 1). All locations were visited at 
least once a month, January- April and November and December. Known breeding 
locations were visited in May to band nestlings. During each visit (excluding 
incubation and brood rearing) we collected prey remains and pellets, banded all 
unbanded owls, and recorded the body mass of all owls encountered. The sex of 
adult owls was determined during the breeding season by the presence or absence 
of an incubation patch. Owls encountered between November and April could be 
aged by the color of the underwing. Birds less than one year of age have a 
buffy color on portions of the primaries, secondaries, and greater wing 
coverts. Birds older than one year have a pinkish wash on their new primaries, 
secondaries and greater wing coverts. 

The nest boxes were not visited frequently enough to determine the number 
of eggs laid or hatched or the number of young fledged. 

RESULTS AND DISCUSSION 

Western screech-owls were found at 19 locations during 1989. Ten of the 
locations were not used during the breeding season. Three of the locations 
were occupied during the breeding season but there was no evidence of a 
breeding attempt. Owls attempted to breed at 6 sites. The nest attempt at 
Rabbit Springs failed during incubation. The remaining 5 sites were successful 
at hatching young. At banding 2 boxes contained 1 young, 1 contained 4 young 
and 1 contained 5 young. At the other box the young were fledged, 2 were 
captured and banded but there may have been other young in the vicinity that 
were not found. 

Twenty-three western screech-owls were banded during 1989 prior to 1 
December. Thirteen nestlings, 2 HY, 6 SY, 1 ASY, and 1 AHY owl were banded. 
One nestling was injured during banding and died from the injury. There have 
been 171 western screech-owls (97 nestlings and 74 adult sized owls) banded in 
the study area since 1980. 

In 1989, a owl hatched in the study area was found as a breeding adult. 
Owl #865-37590 was banded as a nestling at the Strike Reservoir site on 10 May 
1987. This owl was found in a owl box at Crane Falls Sturgeon, 12.5 km from 

55 



its natal nest, on 24 January 1988. On 25 March 1989 it was in a owl box at 
Crane Falls Sturgeon with a female owl. There were 3 eggs in the box, and the 
female had an egg in her oviduct. 

Owl #885-02427 was banded as a nestling on 15 May 1989 at the Delta South 
site. It was found in a box at the Strike Camp Treeline II site on 24 November 
1989. The natal and recovery sites are 3.36 km apart. 

We obtained 51 weights from 23 adult size owls (28 female weights, 10 male 
weights and 13 weights from owls of unknown sex) . Female weights ranged from 
195-296 g. Male weights ranged from 186-212 g. The weights of owls of unknown 
sex ranged from 170-256 g. The female that weighed 296 g was weighed during 
laying and had an egg in her oviduct when weighed. 

American kestrels ( Falco sparverius ) nested in boxes at 4 locations (Table 
1) • 



56 



Table 1. Location names and occupancy status at roosting/nesting boxes 
available to western screech-owls in the Snake River Birds of 
Prey Area in 1989. 



Location name Status Nesting success 



Black Butte, Lower Lower roosting 

Black Sands III roosting 

Bruneau Boat Launch roosting 

Bruneau Marsh vacant 

Bruneau Marsh North vacant 

Bruneau Marsh South roosting 

Bruneau Marsh West roosting 3 

Bruneau Rest Stop vacant b 

Cabin Lower breeding unknown success 

Cabin, Upper roosting" 

Castle Creek Mouth North IV breeding unknown success 

Cellar Hole breeding unknown success 

Crane Falls Sturgeon breeding successful 

Delta East vacant 

Delta South breeding unknown success 

Delta West roosting 

Dunes Entrance Pond vacant 

Flat Iron Marsh vacant 

Harris vacant b 

Little Valley School roosting 

Lover idge Bridge vacant 

Orcutt Treeline vacant 

Rabbit Springs breeding unsuccessful 

River Road roosting" 

Strike Camp vacant 

Strike Dam vacant 

Strike Reservoir roosting 3 

Strike Camp Treeline II roosting 

Three Forks roosting 

Tom Draw roosting 3 

Two Forks vacant 



3 Western screech-owls present during the nesting season but not nesting in 

the boxes. 
b American kestrels nesting in box. 



57 



TITLE: Post-nesting Ecology of Long-eared Owls in the Snake River Birds 
of Prey Area, Idaho. 

INVESTIGATOR: Helen Ulmschneider, Raptor Research Center, Boise State 
University 

COOPERATOR: Raptor Research Center, Boise State University 

OBJECTIVES: 

1. To determine the timing, distances, and directions of movements of 
long-eared owls when they leave their nest groves. 

2. To compare prey deliveries by male and female parents during the 
post-fledging period. 

3. To determine whether adult and juvenile hunters select different prey. 

INTRODUCTION 

This paper summarizes results from the second year of a 2-year master's 
study at Boise State University. The basic objective of the study this year was 
to discover the distances and directions of the owls' initial movements when 
they left the desert after nesting. A second objective was to determine 
relative numbers of prey deliveries by male and female parents during the time 
from branching until the females left. In my first season I discovered that 
females deserted their families before the young reached independence. 

A third objective was to determine whether juvenile hunters selected 
Perognathus prey in greater proportion than did adult hunters. This was 
suggested by Marks (1984) from data collected in the SRBOPA in 1980-81. Lastly, 
I collected data on roosting heights of adult and juvenile owls. 

METHODS 

Trapping . I caught adult owls using a mist net with a plastic great horned 
owl statue as a lure. I placed the net near the nest grove, in an open area or 
on a rise where the statue would be silhouetted to the long-eared owls. The 
owls reacted to the statue by dive-bombing it. I trapped at dusk or night, so 
the owls could not see the net. Position of the set was critical: if the 
statue was not silhouetted, the long-eared owls did not react. Changing the 
position to silhouette the statue caused the long-eared owls to immediately 
begin dive-bombing and "yowling" at the statue. 

Radio- tagging ■ I used backpack harnesses to attach 2-stage transmitters 
(Biotrack, Wareham, Dorset, England) to the owls. These transmitters had at 
least twice the range of the single-stage ones I used last year, though they had 
a slightly shorter life of 2.5-3.5 months. I tagged 13 owls from 4 nests, 
including 4 adult females, 4 adult males, and 5 juveniles (Table 1 and Fig. 1). 

The transmitter plus backpack harness weighed 10 g, which averaged <4% of 
an owl's body weight. For the harness, I used either 6-mm elastic or flat 
teflon tubing. I recaptured 2 owls after tagging them, to check fit, and found 

58 



Table 1. Nest sites and radio- tagged Long-eared Owls in the Snake River Birds 
of Prey Area, Idaho, 1988 & 1989. 



Year 


Site 




Radio-Tagged 




Total 






male 


female 


juvenile 


Fledged 


1988 


SDM-G 


1 


1 


— 







BA 


- 


1 


2 


5 




NP-S 


- 


1 


2 


51 SDR 1 1 


1 


2 
Total 












2 


4 


5 


12 


1989 


NP-NW 


1 


1 


1 


3 




SDR-E 


1 


I 


1 


3 




ETS-U 


1 


1 


2 


4 




ETS-L 
Total 


1 


1 


1 


3 




4 


4 


5 


13 



Abbreviations : 

SDM-G Strike Dam Marsh Green 

BA Bruneau Arm 

NP-S Nicholson Pond South 

NP-NW Nicholson Pond Northwest 



SDR Strike Dam Rd 

SDR-E Strike Dam Rd East 

ETS Emigrant Trail South, upper and lower 



59 



en 
o 



o 
* 



N 



i i 



i — j * 



5 km 



NP*™ 



1988 

1989 

BA Bruneau Arm 

ETS Emigrant Trail South, (upper, lower) 
NP Nicholson Pond, (south, northwest) 
SDM Strike Dam Marsh 
SDR Strike Dam Rd, (east, west) 



ETS ^r 





Figure 1: Locations of study nests of Long-eared Owls for 
1988 and 1989 in the Snake River Birds of Prey 
Area, Idaho. 



that I had been making the back length too short and the owls were developing a 
crusting on the harness where it rubbed behind the wing. When fitting a harness 
it is important to realize that the fit seems much looser while the birds are 
lying on their backs than when they are upright in a natural posture. 

I determined that the harness should be about 330 mm long, allowing 15 mm 
for overlap of the ends to form a continuous loop. The 2 side loops should each 
be 145 mm, allowing 50 mm length in front of the wing from the radio to the 
breast sewing, and 95 mm at the back. This varied somewhat depending on the 
size of the owl, however, I found this to be a good proportion for an even fit 
front to back. I needed 0.5-0.75 hr. to sew the harness on an owl by this 
method. 

Alternatively, I tried sewing several harnesses using 4 separate ends 
instead of 2 loops, sewing them together at the breast. The purpose of doing it 
this way was to allow the harness to drop off when the transmitter had died and 
the stitching (cotton) had rotted. However, it was much more difficult to fit, 
and required over an hour to sew. 

Aerial tracking. I hired the State Bureau of Aeronautics Cessna 182 to 
search for owls. The plane was equipped with 2 H-antennas mounted on the wing 
struts, pointing sideways and down at a 30 degree angle. I flew lines about 
24-32 km apart, paralleling the lay of the front range. When I found an owl, 
location was determined using both maps and a Loran, with accuracy within 2-4 
km. 

Night watches. I conducted night watches at each site from dusk to 
1200-0100, 1-2 times a week. The purpose of these was to track the development 
of the young and to compare prey deliveries by male and female parents. During 
a nightwatch I recorded flying, visits by adults, and changes in numbers and 
intensity of young food-begging. I determined when owls were flying by 
fluctuations in the volume and directions of radio signals. 

I could not usually see prey deliveries, so I had to determine what 
happened by listening. I defined a prey delivery as a visit to the young by an 
adult, accompanied by a change in number or intensity of young food begging 
either before or after the visit. 

Food Habits. I collected pellets throughout the season, recording roost 
site and what owl(s) used it, if known. Pellets were analyzed by soaking them 
in a 7% solution of NaOH to dissolve the hair, and using skulls, dentaries, or 
( for larger species ) , long bones to identify species and numbers of prey items . 
Within a sample of pellets, I counted the number of a prey species as the number 
of skulls, right or left jaws, or (for Dipodomys , Thomomys , and leporids) right 
or left femurs, humeri, or tibia-fibulas, whichever was greatest. 

Roost sites. I visited nest groves every 1-2 days, and tried to spot 
roosting owls without flushing them. I sketched the position of owls, and 
returned later to take measurements. The position of whitewash and pellets also 
helped relocate roost sites. The owls reuse the same few trees over and over, 
causing much auto-replication within the roost site data I collected in 1988. 
Because of indications from the first season's data that newly branched owlets 
roost higher than adults and older juveniles, roost height was the variable I 
measured this year. 



61 



RESULTS 

The results from this study are being written as a Master's Thesis at Boise 
State University. I briefly summarize them here. 

Prey Delivery Rates. Males delivered. 2.45 as many prey items as females, 
during the period from branching to the departure of the females. This factor 
varied among sites, however (Table 2, Fig. 2). The males then continued to 
feed the young for a mode of 19 more days, until both they and the young left 
the desert (Fig. 3). Prey delivery rates for the same owls on different nights, 
and among different owls varied greatly (Fig. 3). Within each pair of owls, the 
male had the greatest overall prey delivery rate (Table 2), although on 2 
occasions the female surpassed the male in a particular night (Fig. 3). 

Timing of Movements. In both years, all the females left their nest groves 
before the males and juveniles, when the young were about 8 weeks old (Fig. 4). 
However, 2 females left at an earlier stage, when the young were about 6.5 weeks 
old; both these females were from late nests, about 2 weeks behind the other 
nests. Most of the males and juveniles then left when the young were about 
10-11 weeks old. 

Local movements. Most of the owls roosted in their nest groves until 
leaving the desert; however there were some local movements (Figs. 5 and 6). 
Five of the successful females from both years started to roost away from their 
nest groves just prior to departing the desert. Except for 1 owl, when the 
females began roosting away from their young, either in separate clumps within 
the same grove, or in different groves, it was a sign they would soon desert 
their families. 

Three of the 5 successful radio-tagged males roosted in their nest groves 
until leaving the desert. Two males roosted up to 2.7 km away from the nest 
grove on scattered days, but continued to feed their young. 

At 2 sites in 1989, I observed mixing of broods of young before they left 
the desert . At ETS ( see Table 1 for abbreviations ) , where there were 2 nests 
6 m apart, the broods roosted together from the time the younger brood branched 
until the older brood left the desert. At night, both broods food-begged 
together. All 4 parents fed the young, however, I could not tell which parents 
fed which young. 

The second case of brood mixing occurred after the SDR brood reached 
independence. The 3 young from SDR moved to Nicholson Pond N (1.5 km away) and 
roosted for about 2 weeks with the younger brood there. 

Long-range Movements. In 1988, I did not find any owls once they left the 
desert. I searched 13,000 km by truck and 18 hrs from the air, in SW Idaho 
(Fig. 7). 

In 1989, I found 7 of the 13 owls after they left the desert: 3 females, 2 
males, and 2 juveniles (Fig. 8). All of the these owls moved northward into the 
mountains. Males, females, and juveniles from the same family went to widely 
separated areas. Directions ranged from 342 to 64 degrees, with 4 clustering 
between and 14 degrees east of north (Fig. 9). My initial locations of owls, 



62 



Table 2. Summary of night watches and prey deliveries at 4 nest sites of 

long-eared owls in the Snake River Birds of Prey Area, Idaho, 1989 





NP-NW 


SDR-E 


ETS U 


ETS L 


TOTAL 


# Nightwatches 

# Hrs obs m & f 

# Hrs obs m only 


10 
12 

9 


7 
9.5 
4.5 


7 

9.5 

8 


10 
12 

13 


27* 
33.5* 
26.5* 


# PD m (f present) 

# PD m (alone) 

# PD f 


19 

20 

2 


16 
4 

7 


9 

5 

8 


10 
4 
7 


54 
33 
22 


Av, PD/hr m 
Av. PD/hr f 


1.9 
.2 


1.4 
.7 


1.2 
.6 


.6 

.6 


1.3 
.5 


Ratio m/f PD 

(f present) 


9.5 


2.3 


1.5 


1.4 


2.5 



* Total reflects the fact that at ETS U & L, nightwatches were done 
simultaneously . 

m - male f - female PD - prey delivery 



63 



CX>. 




NP-NW 



SDR-E 



ETS1 



ETS2 



m 

Ly 

CT 
LU 

> 

LU 

D 

>- 
LU 
CC 
a. 

tt 

_i 
< 
h- 
O 



MALE 
FEMALE 




NP-NW 



SDR-E 



ETS1 



ETS2 



Figure 2: Average prey delivery rates and total number of prey 
deliveries by male and female parents during the post- 
fledging period. Data from night watches (dusk to 12 00- 
0100) at 4 nest sites of Long-eared Owls in the Snake 
River Birds of Prey Area, Idaho, 1989. 



^^■■[HK:' 



EMGRANT TRAIL SOUTH 1 




15 35 

AGE OF YOUNG IN DAYS 



2.8 
2.4 
2- 
1.6- 

1.2 
0.8 
0.4 





EMIGRANT TRAILS 2 




NICHOLSON FOND 



tr 
x 
tr 

ID 

a. 
in 

yj 

tr 
\n 

_i 

ID 

D 
>- 




AGE OF YOUNG IN DAYS 



STRIKE DAM RD E 




■ MALE 
+ FEMALE 



Figure 3: Prey delivery rates for male and female parent Long- 
eared Owls during the post-fledging period, in the Snake 
River Birds of Prey Area, Idaho, 1989. 



65 



nannm^ 



(f) 



n 

E 

2 



10-| 
9- 
8- 
7- 
6- 
5- 
4- 
3- 
2- 
1 - 

o-J- 



J 



8 



I 



1988 



■ Adult females 
I I Adult males 
^ Juveniles 

, Spans period 

of departure 



^ 



9 10 11 12 
Weeks of Age 



13 



n 



14 15 



05 



| 

3 



8n 
7- 
6- 
5- 
4- 
3- 
2- 
1 - 
0-- 



8 



s 



S § 






I I 



1989 



■ Aduit females 
I I Adult males 
£§§ Juveniles 



10 11 12 13 14 15 



Weeks of Age 



Figure 4: Timing of departures of adult male, female, and juvenile 
Long-eared Owls from their nest groves in the Snake 
River Birds of Prey Area, Idaho, 1988 and 1989. 



66 






i i j 1 1 1 



5 km 




2 wks 



1-2 wks ! day 




^ 1988 nest 

^L. 1989 nest 
9 adult feraa 



O 1988 roost 

■ 1989 roost 

le adult male 



^see fig 6 
for these nests 



Bruneau 



Figure 5: Local movements of Long-eared Owls to day roosts away 
from their nest groves in the Snake River Birds of Prey 
Area, Idaho, 1988 and 1989. Length of days a roost was 
used is indicated near it. Arrows indicate direction of 
movement. 



oo 



yC nest 
u upper 



I lower 

o ad. male 
j juvenile 



X roost used 1-4 times 
▲ roost used >4 times 
* indicates last roost 

used before leaving 
^ ad. female 



1 KM 






r 




/ 




./ 


<}+\ f' 

A* 
J 


J s : 




4 


/ 






/ '■ 






/ 




x* x 





J ' nests 



Figure 6: Local movements of Long-eared Owls away from their 

nest grove at Emigrant Trail South, in the Snake River 
Birds of Prey Area, Idaho, 1989. These movements were 
made after nesting and before leaving the desert. 



ID 




Figure 7: Aerial search routed for radio-tagged Long-eared Owls 
after they disappeared from their nest groves in the' 
Snake River Birds of Prey Area, Idaho, in 1988 



^SSBnHHBHHB^HKME 




Nevada 



Figure 8: Locations (•) of 7 radio-tagged Long-eared Owls after 
they left their nest groves (•) in the Snake River Birds 
of Prey Area, Idaho. Number of days owls were tracKea 
after leaving is indicated near last locations. Area 
searched is approximately that of the map. 

f: adult female m: adult male j: juvenile 



70 



N 




Figure 9: Azimuths (in degrees) of initial locations of 7 Long- 
eared Owls after they left the Snake River Birds of Prey 
Area, Idaho, in 1989. 
f: adult female m: adult male j: juvenile 



71 



usually within a week of their departure, ranged from 72-96 km from their nest 
groves (Table 3). The farthest subsequent location was 125 km from the nest 
grove . 

I conducted the first aerial search 2-8 days after the 4 females left, then 
once a week for 4 more weeks, then 1 last time after a delay of 4 weeks (Table 
3). I located the 2 juveniles only once each after they left the desert. I 
found 1 of the ETS 2 owlets 12 days after it disappeared from the desert, on an 
open mountain ridge 80 km north. I found the NP-NW owlet 3 days after it left, 
in a box-elder maple ( Acer negundo ) in a residential backyard in Boise. I 
followed this owl by truck that evening. It flew due north, going over 30 km in 
less than 1 hr. When last heard it was veering NE into forested mountains. 

I was able to track the 5 adults for 21-38 days after they left the desert, 
relocating individuals from 3-8 times by air and ground. After their initial 
movements into the mountains, the adults moved shorter distances, from 0-30 km, 
and settled in 1 general area (Fig. 8). My last contact with them was on 14 
July. I flew again on 10 August, going to the last locations of each owl and 
also searching farther north and east, without finding any signals. I think the 
radios were dead, as they were supposed to last 2.5-3.5 months, and it had been 
3+ months for most of them. 

Food Habits. The pellets from 1989 are still being analyzed. I present 
here the data from 1988, representing 201 prey items. The complete list of prey 
is presented in Table 4. Peromyscus (33%), Perognathus (30%), Dipodomys (14%), 
Microtus (9%), Thomomys (6%), Reithrodontomys (3.4%), and Mus (3.1%) were the 
major prey species by frequency. Young leporids, Neotoma , and birds constituted 
<1% each of the diet. Fig. 10 depicts the overall percent frequency of the 
major prey species. 

Fig. 11 depicts the changes in percent of prey species in the diet from 
April thro ugh July. The percent of Peromyscus declined over this period, while 
that of Perognathus increased. This varied among sites, however (Fig. 12). My 
pellet samples were not equally distributed among the different sites over time, 
and therefore the changes in percentages of prey species may be affected by the 
distribution of samples. However, the high % of Perognathus in the diet during 
late summer holds for 4 of the 6 sites. 

Marks (1984) also found an increase in Perognathus during the post-fledging 
period (June and July), in conjunction with a decrease in Dipodomys . He 
suggested that newly fledged hunters may choose smaller prey. However, I found 
that a lone adult male which stayed at Crane Falls Sturgeon from June-Sept 
consumed 80-90% Perognathus (Fig. 12). Also, during nightwatches , fledged 
owlets seemed to do little flying (hunting), and food begged for most of the 
night until the time they disappeared. Therefore, most of the prey eaten by 
post-fledged owlets before they leave the desert is probably captured by their 
parents. This suggests that the increase in Perognathus in June and July may be 
owing to changes in population or availability of the prey species rather than 
prey choice by the owls. 



72 



Table 3, 



Pio^ 8110 ^ ^ km ) long-eared owls moved from last location, in southwest Idaho, 
1989. Transmitters were probably dead on 10 August. 













June 










July 






August 
10 


NEST 


SEX/ Date left 


15 


18 


23 


25 


30 


2 


7 


10 


14 


16 




Age 


nest area 


air 


grnd 


air 


grnd 


air 


grnd 


air 


grnd 


air 


grnd 


air 


ETS U 


F 


07 June 


97 


2 


16 




* 




2 




<2 




;•; 


SDR-E 


F 


10 June 


84 





















;;: 




ft 


NP-NW 


F 


12 June 


77 


- 


31 










2 


2 


5 




$ 


SDR-E 


M 


21 June 






82 


6 


2 




19 


11 


2 





;': 


ETS U 


M 


25 June 








32? 


>:; 





89 




6 


5 


;■; 


ETS U 


J 


25 June 














84 


* 


* 




■> 


NP-NW 


J 


12 July 


















73,32+ 


* 


* 



- not searched for 

* searched for but not found 

? location approximate 



Table 4, 



Numbers and percents of prey species (by frequency) in the diet of 
long-eared owls in the Snake River Birds of Prey Area, Idaho, during 
April -November, 1989. > "s 



PEMA 

PEPA 

DIOR 

MIMO 

THTO 

REME 

MUMU 

LEP 

BIRD 

NELE 



TOTAL 
% 



APR 
NO. 



196 
69 
51 

S5 
4 

18 
2 
9 
5 
2 



46.6 

16.4 

12.1 

15.4 

1 

4.3 

0.5 

2.1 

1.2 

0.5 



421 
21 



MAY 
NO. 



241 

119 

80 

64 

34 

19 

13 

5 

3 

3 



581 
28.9 



% 



41.5 

20.5 

13.8 

11 

5.9 

3.3 

2.2 

0.9 

0.5 

0.5 



JUN 
NO. 



% 



185 

282 

133 

32 

83 

24 

47 

7 







23.3 
35.6 
16.8 

4 
5 
3 
5.9 
0.9 





10 



793 
39.4 



PEMA 
MIMO 
MUMU 



Peromyscus 

Microtus 

Mus 



JUL 
NO. 



10 
72 
6 
11 
3 
3 
1 

I 




107 
5.3 



9.3 

67.3 

5.6 

10.3 

2.8 

2.8 

0.9 



0.9 





AUG-NOV 
NO. 



% 



30 
61 

9 

1 
5 


2 
i 



27.5 

56 

8.3 



0.9 

4.6 





1.8 

0.9 



PEPA = Perognathus DIOR 

THTO = Thomomys (neonates) HEME 
LEP = Leporid (neonates) NELE 



109 

5.4 



TOTAL 

NO. 



% 



662 

603 

279 

172 

125 

69 

63 

21 

11 

6 



2011 



Dipodomys 
Reithrodontomys 
Neotoma (neonates) 



32.9 
30 

13.9 
8.6 
6.2 
3.4 
3.1 
1 
0.5 
0.3 



73 



>- 



LJJ 
D 

o 

LU 

lt 



lu 
U 

DC 

LJJ 
OL 




RAB NEO 

MUS BIRD 



PM Peromyscus 
MM Microtus 
MUS Mus 



PP Perognathus DO 
TT neonate Thomomys RM 
RAB neonate leporids NEO 



Dipodomys 
Reithrodontomys 
neonate Neotoma 



Figure 10 : 



1988: Percent frequency of the major prey species in 
the diet of Long-eared Owls from April to September in 
the Snake River Birds of Prey Area, Idaho. 



74 






z 

LU 

(J 

cr 

LU 
CL 




DIPODOMYS 

MICROTUS 

PERCMYSCUS 

PERCDGNATHUS 

THOMOMYS 

REITHRODONTOMYS 



APRIL 



MAY 



JUNE 



JULY 



Figure 11: 



1988: Percent frequency of the major prey species in 
the diet of Long-eared Owls during the nesting and 
post-fledging months of April-July, Snake River Birds 
of Prey Area, Idaho. 



80- 
70 

60 
50 
40 
30 
20 
10 




NICHOLSON POND 





100 

on 

BQ< 

70 

BO 

« 

30- 
20 

* o 
o 



STRIKE DAM RD 



MAY 



JUNE 



APR 



MAY 



JUNE 



JULY 



BRUNEAUAHM 




% 80! 
70 
60 

SO 
40 
30 

2D 
10 




J^_ 



CASTLE MOUTH NORTH 



WAY 



JUNE 



JULY 



APR 



■ 



MAY 



JUNE 



% 60- 



STRIKE DAM MARSH 




96100 

30- 
80- 
70 
60 -I 

50 
40 
30 
20 
10 




CRANE FALLS STURGEON 



rvq aiiaM 



APR 



MAY 



JUNE 



JUNE 



■:■■ 

G 



JULY 



AUG 



SEPT 



Figure 12: 1988: Percent frequency of the major 

prey species in the diet of Long-eared 
Owls, by nest site and month, in the 
Snake River Birds of Prey Area, Idaho. 



H DIPODCMYS 
§1 MICROTUS 

PEROGNATHUS 
PEROMYSCUS 



□ THOMGMYS 



76 



LITERATURE CITED 

Marks, J. S. 1984. Feeding ecology of breeding long-eared owls in southwestern 
Idaho. Can J. Zool. P. 1525-1533. 



77 



'.., :...'■■■ 



TITTLE: 



Home Range and Habitat Use of Ferruginous Hawks in the Snake 
River Birds of Prey Area. 



INVESTIGATORS: Dawn McAnnis Gerhardt, Raptor Research Center, Boise 

State University 
Marc Bechard, Raptor Research Center, Boise State 

University 
Richard Gerhardt, Raptor Research Center, Boise State 

University 
COOPERATOR: Raptor Research Center, Boise State University 

OBJECTIVES: 

1. To determine home ranges of 4 nesting male ferruginous hawks. 

2. To determine habitat use within home ranges. 

3. To determine effects of range fires on home range size and habitat 
use. 

INTRODUCTION 

This is a continuation of a 2-year study begun in 1988 to determine the 
effect burning of native shrub steppe habitat has on habitat use of nesting 
ferruginous hawks. 

METHODS 

Four adult male ferruginous hawks were trapped near their nests between 
15 and 26 May 1989, and equipped with radio-transmitters. Males at the 
following nests were trapped: PP&L 104/4, PP&L 102/1, PP&L 96/3, and Indian 
Creek . 

The observation schedule was divided into 3 blocks. Two different males 
were followed each day during 2 of 3 possible observation periods. Block A 
began 30 min before to 1 hr after sunrise and ended 5-5.5 hrs later. Block B 
began between 1100 and 1200 hrs MST (between 30 and 60 min after Block A 
ended) and lasted 3 hrs. Block C began at 1500 to 1700 hrs MST and 
terminated 4.5-5.5 hrs later. This allowed each bird to be observed for 
12-14 hrs every 7 days. 

Locations, habitat use and activity information were recorded every 15 
min or each time the birds perched or made a foraging strike. Observations 
on 2 radioed males were discontinued when they molted the tail feathers 
holding their radio transmitters before fledging began. Observations on the 
other 2 males continued until after fledging. 

Minimum convex polygon and harmonic mean estimations of home range area 
were computed for each bird using the computer program Home Range (Samuel et 
al 1985). A chi-square goodness-of-fit test was used to determine if 



78 



habitat composition of actual home ranges differed from that which was 
available in circles drawn around the nests using as the radius the farthest 
point the bird was observed from the nest. A second Chi-square test and 
Bonferroni-Z confidence intervals were used to determine if habitats found 
within the home ranges were used in proportion to their availability in the 
home ranges (Neu et al. 1974, Byers et al. 1984). 



RESULTS 

The results of this study will be included in a Master's thesis to be 
completed in 1990. The following is a summary of the results for 1989: 

1. Home range size for the 4 ferruginous hawks monitored in 1989 
averaged 5 . 6 km 2 ( range 4 . 8-6 . 4 km 2 ) . 

2. The range of PP&L 104/4 male consisted of 86% grasses, 13% native 
shrub and 1% shrub/grass mosaic. Of 265 total locations obtained for this 
bird, 91% were in grasses, 9% in native shrub and 0.4% in mosaic. Habitats 
were used in proportion to their availability (X 2 = 5.8, 0.10< P <0.05). 

The range of PP&L 102/1 male consisted of 69% native shrub, 20% 
grasses, 8% mosaic, and 4% other (an old quarry) . A total of 236 locations 
were obtained for this bird. Forty percent of these locations were in 
mosaic, 37% in grasses and 24% in native shrub. This bird used mosaic and 
grasses more than expected and native shrub less than expected (X 2 = 390.1, 
P <0.0001). 

The range of PP&L 96/3 male consisted of 67% mosaic, 30% grasses and 
3% native shrub. Of 155 total locations, 64% were in grasses, 32% in mosaic, 
and 4% in native shrub. This bird used grasses more than expected, mosaic 
less than expected, and native shrub in proportion to its availability in the 
home range (X 2 = 89.0, P <0.0001). 

The range of Indian Creek male consisted of 93% grasses and 7% 
mosaic. Of 153 locations obtained for this bird, 98% were in grasses and, 2% 
in mosaic. This bird used mosaic less than expected and grasses in 
proportion to availability (X 2 = 6.9, 0.0K P <0.25). 

3. There did not seem to be any correlation between amount of home 
range burned in the past and fledging success of ferruginous hawks in this 
study (Table 1). 



LITERATURE CITED 

Byers, C. R. , R. K. Steinhorst, and P. R Krausraan. 1984. Clarification of a 
technique for analysis of utilization-availability data. J. Wildl. 
Manage. 48:1050-1053. 

Neu, C. W. , C. R. Byers, and J. M Peek. 1974. A technique for analysis of 
utilization-availability data. J. Wildl. Manage. 38:541-545. 



79 



Table 1. Percent of past-burned habitats in home ranges of ferruginous 
hawks (now represented by grasses) and number of young fledged. 



# Young 
Bird % Burned Fledged 



PPL 104/4 86% 2 

PPL 102/1 20% 4 

PPL 96/3 30% 3 

Indian Creek 93% 4 



80 



Samuel, M. D. , D. J. Pierce, E. 0. Garton, L. J. Nelson, and K. R. Dixon. 

1985. User's manual for Program Home Range, Second ed. For., Wildl., 
and Range Exp. Sta. , Tech. Rep. 15. Univ. Idaho, Moscow. 70pp. 



"* iiiiiihii 



TITLE: Morphometric and Genetic Variation in Ferruginous Hawk 
Populations . 

INVESTIGATORS: Dale K. Ward, Dep. Biology, Boise State University 
Marc Bechard, Dep. Biology, Boise State University 

COOPERATOR: Boise State University 

A study of genetic and morphometric variation in Ferruginous Hawk ( Buteo 
regalis) populations was initiated in cooperation with Boise State University's 
Master's Program in Raptor Biology. 

Three ferruginous hawk nests on Bureau of Land Management property were 
sampled on 13 and 14 June 1989. These nests were located to the south of 
Indian Creek Reservoir, at Bryans Run, Slaters Flat and Indian Creek. Each 
nest contained 4 nestlings, each of approximately 40 days old or older 
(Moritsch 1985). 

A 1.5 ml. blood sample was withdrawn from the branchial vein of each 
nestling for genetic analysis. The nestlings were banded with United States 
Fish and Wildlife Service bands, weighed, and measurements made of the 
following lengths: wing chord, footpad, tarsal, hallux, middle tail feather 
and primary feather #4 (Table 1). 

One sample from each nest was sent to Sheila Schmutz at the Department of 
Biology, University of Saskatchewan, Saskatoon, Canada S7N OWO for genetic 
analysis utilizing DNA fingerprinting. Results of this analysis are still 
pending. The remainder of the blood samples are stored with Dr. Marc J. 
Bechard at the Biology Department, Boise State University, Boise, Idaho 
83725. Further inquiries concerning this project should be directed to Dr. 
Bechard. 



LITERATURE CITED 

Moritsch, Marc Q. 1985. Photographic guide for aging nestling ferruginous 
hawks. Dep. Inter., Bur. Land Manage. Boise, Idaho 21pp. 



82 



Table 1. Characteristics of ferruginous hawks sampled in 1989. 



co 

(a) 



Bird! 


Date 


Nest 


Age 


Band 


Weight 


Footpad 


Tarsus 


Talon 


Beak 


Tail 


Primary 4 


Chord 


Chord 








(days) 


Number 


(kg) 


(m) 


(mm) 


(mm) 


(mm) 


(mm) 


(mm) 


(mm) 


flat (mm) 


1 


13 June 89 


Bryans Run 


45 


87724318 


1.15 


75.1 


82.3 


24.3 


22.3 


150 


230 


324 


327 


2 


13 June 89 


8ryans Run 


45 


87724319 


1 


10 


73.4 


86.5 


23.7 


22.2 


158 


241 


317 


336 


3 


13 June 89 


Bryans Run 


45 


87724320 


1 


03 


62.0 


83.7 


23.7 


21.7 


141 


214 


314 


318 


4 


13 June 89 


Bryans Run 


45 


120723457 


1 


72 


73.3 


86.8 


28.3 


26.8 


146 


231 


315 


321 


5 


13 June 89 


Slaters Flat 


45 


120723458 


1 


58 


83.9 


90.7 


28.6 


25.5 


152 


215 


305 


322 


6 


13 June 89 


Slaters Flat 


45 


120723459 


1 


64 


78.7 


94.5 


29.6 


25.4 


142 


231 


314 


319 


7 


13 June 89 


Slaters Flat 


45 


120723460 


1 


52 


80.4 


85.3 


27.3 


25.3 


141 


205 


288 


302 


8 


14 June 89 


Slaters Flat 


45 


87724321 


1 


10 


72.3 


84.6 


24.4 


23.2 


151 


208 


300 


301 


9 


14 June 89 


Indian Creek 


40 


87724322 


1 


08 


75.8 


83.6 


24.3 


23.2 


136 


197 


274 


290 


10 


14 June 89 


Indian Creek 


40 


120723461 


1 


51 


88.1 


90.1 


26.5 


24.6 


121 


192 


291 


292 


11 


14 June 89 


Indian Creek 


40 


120723462 


1 


50 


86.9 


85.1 


26.9 


23.8 


120 


162 


262 


263 


12 


14 June 89 


Indian Creek 


40 


87724323 


1 


00 


66.9 


79.7 


24.0 


20.9 


131 


125 


283 


284 


Average 










1.07 


61.1 


68.8 


20.8 


19.0 


113 


163 


239 


245 


Standard Deviation 








0.60 


32.4 


35.8 


10.9 


10.0 


59 


10.0 


125 


128 



TITLE: 



INVESTIGATORS: 



Testing Performance of Wildlife Telemetry Equipment in the 
Orchard Training Area 

Mark R. Fuller, U.S. Fish and Wildlife Service, Patuxent 

Wildlife Research Center 
Brett A. Hoover, U.S. Fish and Wildlife Service, Patuxent 

Wildlife Research Center 
Susan S. Klugman, U.S. Fish and Wildlife Service, Patuxent 

Wildlife Research Center 
Linda S. Schueck, U.S. Army Chemical Research, Development and 

Engineering Center, Aberdeen Proving Ground 
Kimberly Titus, Dep. of Fisheries and Wildlife Science, 

Virginia Polytechnic Inst, and State University 
Diane S. Chu, U.S. Fish and Wildlife Service, Patuxent Wildlife 

Research Center 



C00PERATORS: 



OBJECTIVE: 



Idaho Army National Guard 

U.S. Army Chemical Research, Development and Engineering Center 
U.S. Fish and Wildlife Serv. , Patuxent Wildlife Research Center 
Virginia Polytechnic Institute and State University 

Test reception range, accuracy, and function of telemetry 
equipment for potential application to studies of raptors in the 
Snake River Birds of Prey Area. 



INTRODUCTION 

Research is proposed for learning about the movements, habitat selection, 
and general behavior of raptors using the Idaho Army National Guard Orchard 
Training Area (OTA) and adjacent area within the Snake River Birds of Prey 
Area. Radio telemetry is a potential research technique because of the 
limitations to repeated direct observation of the rapid-moving, wide-ranging 
raptors and to researchers' mobility in the study area. Furthermore, 1 goal of 
the research is to study raptor movements during the military training that 
takes place on the OTA. During periods when tank, artillery, or helicopter 
weapons training is underway, about 60% of the OTA is closed to ground and air 
access. Therefore, "location" of raptors must be accomplished by telemetry 
conducted from the Range Road (perimeter of the impact zone) or beyond. This 
report summarizes some of the telemetry test results obtained to date. 
Additional analyses may provide some different interpretations, and allow for 
more distinction among the effects of some variables. 



METHODS 

We assessed the feasibility of a telemetry study on the OTA using 2 
criteria, (1) evaluation of bearing error defined to be the known bearing minus 
the observed bearing (Chu et al. 1989), and (2) evaluation of location estimates 
based on distance of the point estimate from known transmitter location, area of 
the confidence ellipse associated with the point estimate, and the coverage that 
the confidence ellipse gave (i.e., whether the transmitter was within the 
ellipse) . 



84 



We obtained bearings towards transmitters placed 0.3m and 1.5m 
above-ground at USGS benchmarks on the OTA. These transmitter locations were 
unknown to the observers obtaining the bearings. The first (summer) test period 
started on 23 August and ended 28 August. The second (fall) test period was 31 
October and 1 November. We used 3 sizes of 164-mHz transmitters (in order of 
increasing size these were "merlin", "hawk", and "eagle" transmitters) and 3 
antenna positions: hand-held, and 3.05-m and 6.1-m towers with metal or PVC 
plastic masts. Towers were erected on buttes accessible from Range Road on the 
OTA. The antennas were a 4-element Yagi configuration, and were connected to 
scanning receivers: Advanced Telemetry Systems Model 2000 (ATS) and LOTEK Model 
SRX-400 (use of product names does not imply endorsement) . 

During the summer observations, we used 3.05-m and 6.1-m towers constructed 
from metal masts, and ATS receivers only. During the fall observations, merlin 
transmitters were not used, and we used 3.05-m towers equipped with upper-masts 
constructed of PVC pipe rather than metal. For the fall observations, we used 
both ATS and LOTEK receivers. The LOTEK receiver contained a built-in meter 
that digitally displayed signal strength. Not all signals were powerful enough 
to be recorded on the meter; therefore the receivers were classified into 3 
groups: 1) ATS receiver (no signal strength indicator), 2) LOTEK receiver, 
signal not strong enough to register on meter, and 3) LOTEK receiver, signal 
registered on meter. 



RESULTS 
Analysis of Bearing Error 

Five observers obtained 628 bearings during the summer. The overall 
bearing error was -5.83 degrees (sd = 17.56 degrees). Signals were received 
from up to 30 km away, although no merlin transmitter signal was received at 
distances greater than 10 km. The height of the transmitter did not have any 
effect on bearing error. 

Four factors: observer, antenna position (hand-held, 3.05 or 6.1-m towers), 
distance class (in 5-km intervals), and type of transmitter (merlin, eagle, and 
hawk) were used to assess variables that influence bearing error. All factors 
and 2-way interactions were significant (P _< 0.0433). Almost all of the 
observers were significantly different from one another in mean bearing error. 
Bearings obtained using the hand-held antennas proved significantly less 
accurate than bearings from the 3.05-m towers. There was no difference between 
the 3.05-m and 6.1-m towers or between the hand-held and 6.1-m tower. Although 
distance class was significant, no single distance class emerged from the 
analysis as being the best. Bearings obtained for the merlin transmitters were 
significantly less accurate than for both the hawk and eagle transmitters. 
Bearings taken on the eagle and hawk transmitters were not significantly 
different in accuracy. 

Of the interactions, the following results were most relevant to our 
assessment of error. Mean error for merlin transmitters detected with hand-held 
antennas and 3.05-m tower systems was -25.0 and -12.3 degrees, respectively. 
For the merlin transmitters detected with 6.1-m towers, the mean error was -3.0 
degrees. Distance class and transmitter type interactions also were revealing. 
For the 5-km and 10-km distance categories in which merlin transmitters were 
detected, mean error was -15.1 and -15.3 degrees, respectively. 



The overall mean error for the fall period was -3.37 degrees (s.d. = 15.06) 
from a total of 278 obtained bearings. Antenna method, observer- transmitter 
type, method-distance class, and distance class-receiver class interactions were 
significant (P < 0.0813). The 3.05-m tower data were more accurate than the 
data for the hand-held antenna using the LOTEK (both categories; we gathered no 
fall data using hand-held antennas with ATS receivers ) . The mean error of the 
ATS using 3.05-m towers was -4.24 degrees (s.d. = 16.49, n = 98). At distances 
greater than 25-km, it was not possible to get a reading on the power indicator 
of the LOTEK receivers. The mean error of the LOTEK receivers with 3.05-m 
towers was 1.65 degrees (s.d. = 14.58, n = 58) with the power indicator and 1.45 
degrees (s.d. = 26.86, n = 36) without the power indicator. In pairwise 
comparisons, mean bearing error was not significantly different for the 2 LOTEK 
classes, but the LOTEK with the power indicator functioning was more precise (P 

< 0.00001). The LOTEK with the power indicator was more accurate than the ATS 
receiver (P < 0.0257), but testing of variance between the 2 was not 
significant. In the comparison of the ATS to the LOTEK without the power 
indicator, the means were not significantly different, but the LOTEK was less 
precise than the ATS (P < 0.00001). 

Because the telemetry studies might involve using both tower and hand-held 
systems at the same time, we compared the LOTEK receivers to the ATS receivers 
for all methods together. Again the LOTEK without use of the power indicator 
was less precise than the LOTEK with the power meter (P < 0.00001) or the ATS (P 

< 0.0034). However, there was no significant difference in precision between 
the LOTEK using the power indicator and the ATS when data from the towers and 
hand-held antennas were analyzed together. 

If the assumption is made that the summer and fall test periods do not 
differ, then comparison of the 2 3.05-m tower systems (using the same observer) 
indicates that the 3.05-m system with PVC mast (u = -3.64) is more accurate than 
the 3.05-m tower with a metal mast (u = -8.66, P < 0.0618). 

Analysis of Location Estimates 

Locations were estimated using a least squares estimator (Pace 1988). 
Ninety location estimates were obtained for the summer period. The overall 
average distance error was 3381 m with an average associated 95% confidence 
ellipse of 2541 ha. Actual coverage was 36.7%. Distance class (the average of 
the sum of the receiver- to- transmitter distances classified in 5-km intervals) 
and the antenna method-distance class interaction had an effect on the distance 
error. These, in addition to antenna method, also had significant effects on 
the size of the 95% confidence interval. For the 95% confidence regions, both 
the hand-held antennas and 6.1-m towers gave more useful estimates than the 
3.05-m towers (P _< 0.05). For distance error, only the hand-held antenna and 
3.05-m tower were significantly different (P < 0.05), with the hand-held antenna 
being more accurate. For both 95% confidence area and distance errors, the 
20+km class was significantly different (P < 0.05), and always gave poor 
results . 

Because only 2 observers were used during the fall, location estimates were 
not obtained. However, given that the bearing errors for fall were similar to 
those from the summer period, similar results for location estimates would be 
expected. 



86 



DISCUSSION 

The reception range of the larger hawk and eagle transmitters will be 
adequate for triangulation throughout the area within the Range Road. However, 
the inclusion of the longer distances of reception increases the error between 
the estimated point location and the actual location. The data from the 
shorter-range merlin transmitters illustrate this and the advantage of elevating 
the receiving antenna; the shorter-distance bearings from the higher antenna 
position provided the most accurate bearings. 

To achieve coverage of the OTA, bearings must be taken over comparatively 
long distances, and inclusion of all data resulted in large bearing error (-5.83 
degrees, s.d. = 17.56 degrees), and very large distance errors (3381 m) and 95% 
confidence ellipses (2541 ha). These values would not be very useful for 
understanding raptor movements. Therefore, we tested some ways of potentially 
reducing the error. 

Plastic masts were tested to reduce interference with the antenna reception 
characteristics that a metal mast can cause under some circumstances. Use of 
plastic masts did produce less bearing error than we obtained with metal masts. 
However, rigidity and ease of construction and assembly were reduced with the 
design we employed for the plastic masts. Greater antenna elevation would 
probably improve accuracy, but that will require a more elaborate stand and 
stronger structure (less "portable"), to withstand the force of wind on the 
antenna. 

We tested the signal power indicator on the LOTEK receiver as a means of 
more carefully determining the direction from which the strongest signal was 
coming. The indicator is not activated if signal strength is not of a threshold 
level. Usually, a lack of a reading on the power indicator was indicative of a 
transmission from a longer distance. The combination of a closer transmitter 
plus use of the power indicator did reduce error. 

Additional reduction of error can be obtained with other changes in 
equipment, but the funding available and reduced mobility are 2 important 
limiting factors in pursuing alternative equipment. Another strategy to control 
error is to discard some estimates involving very long distances, or very large 
or small angles between 2 receiving points and the transmitter (e.g., Chu et al. 
1989 ) . Access restricted to the area along the Range Road limits the extent to 
which this strategy can be employed. We continue to explore options for 
reducing error. However, these preliminary results suggest that the specific 
research objectives will be shaped to some (potentially large) extent by the 
precision of raptor location estimates that can be achieved. 

ACKNOWLEDGMENTS 

This pilot study was made possible by funds from the Idaho Army National 
Guard through Col. J. Kane, Chief of Staff, and by support and advice from W. S. 
Seegar, U.S. Army Chemical Research, Development and Engineering Center. The 
National Guard also assisted in field communications, and we are especially 
grateful to staff in Range Control and Fire Suppression. M. Blew and M. Drake 
(National Guard), and J. Doremus (BLM) took us to benchmarks; this was not an 



87 



enviable task! J. D. Fraser and P. Schempf loaned us transmitters. Mobility, 
communication and coordination in the field are essential for triangulation 
telemetry. Our tests would not have been possible without the vehicles and 
2-way radio communications provided by the BLM. M. Kochert and K. Steenhof were 
instrumental in arranging these. Our sincere thanks are extended to S. Senchak 
and D. Clugston, who conducted fieldwork with us. 



LITERATURE CITED 

Chu, D. S., B. A. Hoover, M. R. Fuller, and P. H. Geissler. 1989. Telemetry 
location error in a forested habitat. Pages 188-194 in C. J. Amlaner, 
Jr., ed. Biotelemetry X: Proc. of the 10th Internatl. Symp. on 
Biotelemetry. Univ. of Arkansas Press, Fayetteville. 

Pace, R. M. , III. 1988. Radiotracking wildlife by triangulation: an 

evaluation of directional measurement errors and location estimators. 
Ph.D. Thesis, Purdue Univ., West Lafayette, IN. 



88 



TITLE: Abundance of Lagomorphs and Rodents in the Snake River Birds 

of Prey Area. 

INVESTIGATORS: John Doremus, BLM Bruneau Resource Area 
Marjorie Blew, Idaho Army National Guard 
Steve Knick, BLM Birds of Prey Research 

OBJECTIVE: To monitor changes in the Black- tailed jackrabbit ( Lepus 
californicus ) population in the Snake River Birds of Prey 
area. 



INTRODUCTION 

We conducted spotlight surveys along 13 previously established transects 
and one new transect (Range 3). The transects run through major cover types 
within the study area (Table 1). The Range 3 transect is 6.78 km in length and 
runs through big sagebrush ( Artemisia tridentata ) , grass (native and exotic), 
and big sagebrush/grass. 



METHODS 

Each transect was sampled 3 times from 15 May to 3 June, using the method 
of Smith and Nydegger (1985). A total of 709 km was sampled in 1989. The 
Range 3 transect was selected using the guidelines from the black-tailed 
jackrabbit spotlight survey instruction memo on file at the Boise District 
Office. Data were analyzed using the computer program "TRANSECT" (Burnham et 
al. 1980). The location of all kangaroo rats ( Dipodomys prdii, D. mi crops ) , 
Nuttall's cottontails ( Sylvilagus nuttalli) , pygmy rabbits ( Brachylagus 
idahoensis ) , voles ( Micro tus spp. and Lagurus curtatus ) and mice 
( Re i throdontomys megalotis , Onychomys leucogaster , Perognathus parvus and 
Peromyscus maniculatus ) seen during the jackrabbit surveys were recorded. 

Vegetation was recorded along the length of all transects in April and 
early May prior to the rabbit surveys. With the same vehicle used to survey 
rabbits, all transects were driven during the daylight hours. The mileage at 
the start of the transect and at each change in vegetation was recorded to the 
nearest hundredth of a mile. Vegetation classifications were ocular and based 
on the observer's subjective assessment of the vegetation changes. 

The mileage at each small mammal sighting was recorded to the hundredths 
of a mile. The location of a small mammal sighting was compared with the 
vegetation mileage to determine the vegetation type where the mammal was seen. 



RESULTS AND DISCUSSION 

The number of jackrabbits observed on the 11 baseline transects increased 
from 175 in 1988 to 265 in 1989. The annual density index for all cover types 
increased from 0.41 jackrabbits/ha in 1988 to 0.59 jackrabbits/ha in 1989 
(Table 2). The density of jackrabbits/ha decreased from 1.33 to 1.05 in the 
big sagebrush types from 1988 to 1989 (Table 3). 



89 



Table 1. Kilometers for the black- tailed jackrabbit transects by habitat type 
1989. 



Habitat type Kilometers 



Grass 179.47 

Big sagebrush 114.86 

Big sagebrush/Grass 108.96 

Big sagebrush/Winterfat 46.32 

Shadscale 43 - 10 

Crested wheatgrass 42.00 

Shadscale/Grass 30.91 

Big sagebrush/Shadscale 25.39 

Winterfat/Shadscale 22.94 

Winterf at 18.72 

Winterf at/Spiny hopsage 13.30 

Greasewood 11.57 

Winterf at/Grass 10.03 

Greasewood/Shadscale 9 . 22 

Greasewood/Halogeton 7.92 

Big sagebrush/Crested wheatgrass 5.71 

Rabbi tbrush/Grass 5 . 18 

Bare ground 3.74 

Big sagebrush/Spiny hopsage 2.78 

Big sagebrush/Nuttall saltbush 1«?8 

Halogeton l* 78 

Grass/Bare ground 1.63 

Big sagebrush/Bare ground 1.15 

Spiny hopsage/Grass 0^58 

Total 709.04 



90 



Table 2. Line transect results for jackrabbit censuses from 1977 through 
1989. Transects include all habitat types. Density index was 
determined by the exponential power series estimator from the 
program TRANSECT. 











Density 










Distance 


No. 




Index 








Year 


(km) 


Jackrabbit s 


n/km 


n/ha 


95% 


C.I. 


c.v. 


1977 


270.68 


218 


0.81 


0.231 


0.200 


- 0.261 


6.77 


1978 


262.74 


103 


0.39 


0.322 


0.260 


- 0.385 


9.85 


1979 


562.52 


701 


1.25 


0.747 


0.692 


- 0.803 


3.78 


1980 


562.52 


807 


1.43 


0.654 


0.471 


- 0.837 


14.29 


1980a 


562.52 


807 


1.43 


0.480 


0.473 


- 0.527 


4.98 


1981" 


534.76 


870 


1.63 


0.778 


0.516 


- 1.040 


17.17 


1982 


541.17 


282 


0.52 


0.196 


0.105 


- 0.287 


23.74 


1983 


538.61 


194 


0.36 


0.183 


0.157 


- 0.209 


7.18 


1984 


536.54 


59 


0.11 


0.082 


0.061 


- 0.103 


13.02 


1985 


536.36 


55 


0.10 


0.030 


0.022 


- 0.038 


13.48 


1986 


549.34 


29 


0.05 


0.057 


0.036 


- 0.078 


18.57 


1987 


613.69 


85 


0.14 


0.078 


0.061 


- 0.094 


10.85 


1988 


674.00 


190 


0.28 


0.406 


0.348 


- 0.464 


7.25 


1989 


709.04 


281 


0.40 


0.591 


0.522 


- 0.660 


5.97 



a / Density index determined by negative exponential estimator. 
b / Data truncated (w < 100 m) . 



91 



Table 3. Line transect results for jackrabbit censuses from 1977 through 

1989. Transects include only sage brush habitats (Types 01, 02, 03, 
22, 23, 24, 41, 42, 43). Density index was determined by the 
exponential power series estimator from the program TRANSECT. 



Density 
Distance No . Index 

Year (km) Jackrabbits n/km n/ha 95% C.I. C.V. 



60 1.54 0.312 0.233 - 0.391 12.91 

54 0.73 0.797 0.585 - 1.010 13.61 

412 1.88 1.208 1.091 - 1.325 4.93 

445 2.00 1.046 0.670 - 1.422 18.34 

455 2.04 1.067 0.664 - 1.471 19.30 

466 2.50 1.323 0.829 - 1.817 19.05 

158 0.87 0.385 0.146 - 0.624 31.64 

163 0.90 0.400 0.162 - 0.637 30.30 

94 0.54 0.458 0.366 - 0.551 10.31 

99 0.57 0.465 0.373 - 0.556 10.05 

36 0.23 0.127 0.085 - 0.168 16.67 

25 0.17 0.056 0.034 - 0.079 20.00 

14 0.13 0.087 0.042 - 0.133 26.73 

45 0.43 0.152 0.108 - 0.196 14.91 

86 0.86 1.327 1.046 - 1.607 10.78 

64 0.56 1.047 0.791 - 1.304 12.50 

a / Data set from file on disk. 

b / Data set adjusted by reconstruction from frequency distribution 
of distances in raw data. 

c / Data truncated (w < 100 m) . 



1977 


39.07 


1978 


73.98 


1979 


219.14 


1980* 


222.51 


1980b 


222.51 


1981= 


186.40 


1982* 


181.40 


1982b 


181.40 


1983* 


174.20 


1983b 


174.20 


1984 


155.40 


1985 


147.30 


1986 


105.96 


1987 


103.97 


1988 


99.77 


1989 


114.61 



92 



The number of kangaroo rats seen per unit (n/km) varied from 0.00 to 5 17 
depending on cover type (Table 4). Kangaroo rats were found in all cover types 
in the survey area except big sagebrush/bare ground, grass/bare ground and big 
sagebrush/crested wheatgrass. For all cover types the number of kangaroo rats 
increased from 0.50 in 1988 to 0.89 in 1989. The number of kangaroo rats 
observed increased from 362 in 1988 to 629 in 1989 (Table 5). 

The total number of Nuttall's cottontails seen decreased from 24 in 1988 
to 13 in 1989 (Table 5). The number of Nuttall's cottontails seen per unit 
effort (n/km) varied from 0.01 to 0.09 in those cover types where they were 
found in 1989 (Table 6). 

The number of pygmy rabbits seen per unit effort (n/km) decreased from 
0.01 in 1988 to 0.004 (Table 7) for all cover types. The total number of pygmy 
rabbits seen decreased from 9 in 1988 to 3 in 1989 (Table 5). 

The number of mice seen per unit effort (n/km) varied from 0.04 to 0.19 in 
those cover types where mice were observed (Table 8). The total number of mice 
observed increased from 28 in 1988 to 43 in 1989 (Table 5). The total number 
of voles seen increased from in 1988 to 1 in 1989 (Table 5). This is the 
first sagebrush vole seen during the jackrabbit transects. 

The drought that began in the fall of 1986, continued through the summer 
of 1989. However, March 1989 had precipitation that ranged from 0.88 inches 
above normal at Grandview, Idaho to 2.43 inches above normal at the Boise, 
Idaho airport, National Oceanic and Atmospheric Administration (1989). The 
temperatures averaged from 2.2 to 2.6 degrees Fahrenheit above average for this 
area for the same time period. These conditions were suitable for the growth 
of annual grasses and forbs and might have hidden some small mammals that would 
have been seen under 1989 conditions. 

The information on Nuttall's cottontails, pygmy rabbits, and kangaroo rats 
could be analyzed on program "TRANSECT" (Burnham et al. 1980), but low numbers 
seen in past years would make comparison of the data very difficult. The 
information on mice and voles was not collected in a manner that allows it to 
be analyzed on program "TRANSECT" (Burnham et al. 1980). 



LITERATURE CITED 

Burnham, K.P., D.R. Anderson and J.L. Laake. 1980. Estimation of density from 
line transect sampling of biological populations. Wildl. Monogr. 72. 
202pp. 

Smith, G.W. and N.C. Nydegger. 1985. A spotlight, line-transect method for 
surveying jack rabbits. J. Wildl. Manage. 49:699-702 

National Oceanic and Atmospheric Administration. 1989 Climatological Data, 
Idaho, March 1989. 92(3) :4. 



93 



Table 4. Number of kangaroo rats seen per unit effort (n/km) on the spotlight 
transects within all cover types within the Birds of Prey Area, 1989. 



Cover Type 



1989 



u v. 1-51 

Big sagebrush Q ^ 

Big sagebrush/Nuttall saltbush 

Big sagebrush/Grass 

Big sagebrush/Winterfat 

Shadscale 

Shadscale/Grass 

Big sagebrush/Shadscale 

Winterfat/Shadscale 

Winterfat/Spiny hopsage 

Winterfat/Grass 

Halogeton 

Rabbi tbrush/Grass 

Grass 

Bare ground 

Big sagebrush/Bare ground 

Grass/Bare ground 

Winterfat 

Spiny hopsage/Grass 

Greasewood/Shadscale 

Big sagebrush/Crested wheatgrass 

Crested wheatgrass 

Greasewood/Halogeton 

Greasewood 

Big sagebrush/Spiny hopsage 

All cover types pooled 



0.51 

0.91 

1.23 

0.00 

1.10 

1.22 

0.90 

0,00 

4.49 

2.70 

1.20 

0.80 

0.00 

0.00 

3.42 

5.17 

0.98 

0.00 

1.10 

1.39 

1.90 

0.36 

0.86 



Table 5. Number of small mammals seen on 709 km of spotlight transects, 1989. 



Species 



1989 



Nuttall's cottontails ^ 

Pygmy rabbits 

Mice 

Voles 

Kangaroo rats 



43 

1 

629 



94 



Table 6. Number of Nuttall's cottontails seen per unit effort (n/km) on the 

spotlight transects within selected cover types in the Birds of Prey 
Area, 1989. 

Cover type 1989 

Winterf at/Spiny hopsage 0.09 

Big sagebrush/Grass 0.04 

Big sagebrush 0.02 

Big sagebrush/Winterfat 0.02 

Grass 0.01 

All cover types pooled 0.06 



Table 7. Number of pygmy rabbits seen per unit effort (n/km) on the spotlight 
transects within selected habitat types within the Birds of Prey Area, 
1989. 



Cover types 1989 

Big sagebrush 0.01 

Big sagebrush/Winterfat 0.02 

Big sagebrush/Grass 0.01 

All cover types pooled 0.00 



Table 8. Number of mice seen per unit effort (n/km) on the spotlight transects 
within selected cover types in the Birds of Prey Area, 1989. 

Cover type 1989 

Winterf at/Shadscale 0.04 

Grass 0.12 

Big sagebrush/Winterfat 0.11 

Big sagebrush/Grass 0.06 

Big sagebrush 0.05 

Rabbi tbrush/Grass 0.19 

Crested wheatgrass 0.05 

Big sagebrush/Shadscale 0.04 

All cover types pooled 0.06 



95 



TITLE: Townsend's Ground Squirrel Relative Abundance in the Snake 
River Birds of Prey Area. 

INVESTIGATORS: Susan Wheeler, BLM Birds of Prey Research 
John Doremus, BLM Bruneau Resource Area 
Kristina Timmerman, BLM Birds of Prey Research 
Karen Steenhof , BLM Birds of Prey Research 

OBJECTIVE: To continue monitoring the relative abundance of the 

Townsend's ground squirrel in the Snake River Birds of Prey 
Area. 



ANNUAL SUMMARY 

Active Townsend's ground squirrel ( Spermophilus townsendii or TGS) burrow 
densities increased slightly from 1988 levels, but badger { Taxidea taxus ) 
burrow numbers declined between 1988 and 1989. As in past years, winterfat 
habitat supported the highest mean TGS and badger burrow densities (b/ha) in 
the Snake River Birds of Prey Area (SRBOPA). Exotic annuals supported the 
lowest mean TGS and badger densities in 1989. Habitats with the highest TGS 
burrow densities showed declines in burrow numbers from 1988 to 1989, while 
habitats with low densities showed increases. In range seedings, both TGS 
and badger burrow densities declined from 1988 levels. 



INTRODUCTION 

Townsend's ground squirrels are a major food source for raptors, badgers, 
and other predators. The abundance of prey is a crucial factor contributing 
to the abundance and diversity of raptors in the Snake River Birds of Prey 
Area (Nydegger and Smith 1986). Within the SRBOPA the TGS population can 
vary between years (Smith and Johnson 1985). This variation may be caused by 
predation, dispersal, weather, and disease, and could affect the populations 
of raptors and other predators in the area (U.S. Dep. Inter. 1979). 

Wildfire is a primary cause of change in species composition and 
structure within habitats. In the SRBOPA, over 75,000 ha burned and were 
converted to exotic annuals between 1980 and 1988 (U.S. Dep. Inter, 
unpublished data). Nydegger and Smith (1986) reported that big 
sagebrush/ winter fat ( Artemisia tridentata / Ceratoides lanata) and winterfat 
habitats support higher numbers of TGS than other plant communities in the 
SRBOPA. Because the TGS population appears to have a high association with 
specific plant communities, it was considered important to monitor TGS 
population trends and food habits in altered and relatively unaltered habitat 
types. 



PREVIOUS WORK 

In 1982, 190 hole count transects were established to monitor population 
trends in altered and relatively unaltered habitat types (Johnson et al. . 
1982). In 1986, Peterson and Yensen (1986) re-sampled 60 of these transects 
and established a vegetation canopy coverage transect (Daubenmire 1959) on 



96 



each hole count transect. All 60 transects were permanently marked with 
fence posts in 1986. In 1987, 54 of the 60 transects were re-sampled. 
Hereafter, these 54 transects (sampled in 1982, 1986, 1987, 1988, and 1989) 
are referred to as "core" transects. In addition to the 54 core transects, 
J° ^f?f ect ?u Were est ablished and permanently marked with fence posts in 1986 
^T \Z herB TT e ° f Sma11 raaJimals < incl "ding TGS) and vegSation to a 
!!!";! S in /hadscale (Atriplex cpn ferti foli a) and winterfat habitat 
types (Groves and Steenhof 1988), and 11 transects were established and 
marked with wooden lathes in 1987 to monitor TCS population and vegetation 
trends in burned areas that had been reseeded. In 1988, 81 TCS hole count 

wltT^r^l^^?' A11 transects not Permanently marked were staked 
with rebar in 1988, and fence posts were replaced on transects where they 
were missing. Metal tags with the transect number were attached to fence 
posts on the 54 transects sampled in 1982, 1986, and 1987. Peterson and 
Yensen (1986) concluded that hole count transects seem to be reliable 
estimators of relative TGS density in the SRBOPA. For a detailed explanation 
of the methods used in 1982, 1986, and 1987, see Peterson and Yensen (1986). 



METHODS 



In 1989, 81 TCS hole count transects were sampled. Seventy-nine of the 
transects had been sampled in 1988 (Timmerman et al. 1988). However, 2 new 

iTtefllf 0?\f 4 ^T e eStaMished ^™ the old transect posts "uld 
not be found. Of the 81 transects sampled, 54 were part of the "core" 

habitat ri ^nf r ° UP ^ n big , sa ^ ebrush ' winterfat, shadscale, and exotic annual 
habitat types. Eleven transects, established in 1987, were located in range 
seedings. The remaining 16 transects had been established in 1986 in the 
vicinity of the Black Butte burn and were located in burned, partially 
burned, burned-reseeded, and native vegetation ( shadscale/winterf at ) . 

As in previous years, the belt transect method (Peterson and Yensen 1986) 
was used on all 81 transects. Each transect was a linear str" 40oTlon^ ^ 
and 5-m wide (2000 m* ) . A 5-m flexible pole with lightweight chains 
approximately 1-m long at each end was used to define the transect width. 
One observer held the pole at its center and walked the center line of the 
transect. The observer counted all active and inactive TGS and badger 

tZ° WS ST X i ne - - ACtiVe h ° leS Were ^termined by the censusers as 
those used by ground squirrels or badgers during the year of the census as 
evidenced by tracks, claw marks, and feces, and by sightings oftnTaSmaL 
forth ^Ttt ? nC tl\, A ^u^ ° bserver ^ed systematically back and 
burrows ThV ? R searchl ^ for active and inactive TGS and badger 
burrows. The 2 observers were m constant communication with each other to 
prevent duplication of the burrow count. 

oonnS a i 1 8 + 1 . tra f s f cts ' abundance of TGS and badgers was determined by 
counts of active holes. Inactive holes were also recorded. All TCS and 
badger burrows were converted to burrows per ha to facilitate comparisons 



97 



RESULTS 



The number of active TGS burrows increased from 67.7 per ha in 1988 to 
73.2 per ha in 1989. The total number of burrows counted on 54 transects was 
3955, 300 more than in 1988 (Table 1). Numbers of burrows increased on 25 
transects, decreased on 18, and showed no change on 11. Overall, the 
increase was not statistically significantly different (Wilcoxon signed ranks 
test T = -545.5, n = 43, P = > 0.10). 

Among the 54 "core" transects sampled in 1989, the winterfat vegetation 
type supported the highest mean number of TGS b/ha (Table 2) . Winterfat 
transects have had the highest mean burrow densities in every year since 
1986. However, 1989 burrow densities in winterfat were just slightly over 
half the levels recorded in 1982 and 1987 (Table 2). Sagebrush habitats had 
the next highest burrow densities, followed by exotic annuals and shadscale. 

The 2 habitats with the highest burrow densities in both 1988 and 1989 
showed declines in burrow densities from 1988 to 1989 (Table 2). Numbers of 
burrows decreased on 59% of the winterfat transects and 57% of the sagebrush 
transects. However, burrow numbers increased from 1988 to 1989 in habitats 
with lower burrow densities. All 6 transects in shadscale habitat showed 
increases, and 50% of transects in exotic annual vegetation had increased 
burrow numbers. One transect in exotic annuals (#55) had a 30-fold increase 
in burrow numbers (Table 1). 

The badger population index decreased from 8.8 b/ha in 1988 to 8.5 b/ha 
in 1989. The 1989 badger density was 87% lower than the 1982 density of 66.9 
b/ha (Table 3). As in past years, there was a high positive correlation 
(Spearman rank correlation r s = 0.62, n = 54, P < 0.001) between the number 
of active TGS burrows and active badger burrows on transects in 1989. 

In 1989, 5 transects in stands that have been dominated by exotic annuals 
throughout the study period (1982 - 1989) had higher average TGS densities 
(66 b/ha) than 19 stands that had been converted to exotic annuals since 1982 
(29 b/ha). 

Four years after the Black Butte burn, TGS densities were still higher on 
the control transects (70.0 b/ha) than within the burn (Table 4). As in 1986 
and 1988, transects in partial burns had the second highest densities (51.3 
b/ha) . Densities within the burn increased from 1988 to 1989 in both 
reseeded and untreated habitats. Untreated burned areas had higher densities 
(25.0 b/ha) than seeded sites within the burn (18.8 b/ha). The 16 Black 
Butte burn transects supported an average TGS density of 41.3 b/ha in 1989, 
more than twice the 1988 density of 17.2 b/ha (Table 4). 

In 1989, the 11 range seeding transects supported an average of 36.8 TGS 
b/ha, 36% lower than the 1988 average density of 57.3 b/ha (Table 5). Badger 
densities in range seedings decreased from 17.7 b/ha in 1988 to 3.2 b/ha in 
1989. 



98 



Table 1. Townsend's ground squirrel burrows /hectare on the same transects in 1982 
and 1986 - 1989 in the Snake River Birds of Prey Area, Ada and Elmore 
Counties, Idaho (1982 and 1986 data from Petersen and Yensen 1986). 
Vegetation acronyms are as follows: CELA = winterfat, ARTR = big 
sagebrush , ATCO = shadscale , EXAN = exotic annuals ( cheatgrass , mustards , 
Sandberg ' s bluegrass ) . 





















Active 




# 


Transect 




Vegetation 


^s 








Burrows/ha 






# 


1982 


1986 


1987 


1989 


1982 


1986 


1987 


1988 


1989 


1 


4 


CELA 


CELA 


CELA 


CELA 


CELA 


735 


315 


505 


455 


410 


2 


5 


CELA 


CELA 


CELA 


EXAN 


CELA 


131 


230 


320 


55 


85 


3 


6 


CELA 


CELA 


CELA 


CELA 


CELA 


232 


180 


240 


80 


65 


4 


7 


CELA 


CELA 


CELA 


CELA 


CELA 


373 


260 


645 


225 


175 


5 


13 


CELA 


CELA 


CELA 


CELA 


CELA 


624 


370 


120 


275 


210 


6 


14 


CELA 


CELA 


CELA 


CELA 


CELA 


342 


100 


250 


315 


185 


7 


15 


CELA 


CELA 


CELA 


CELA 


CELA 


453 


150 


625 


295 


265 


8 


16 


CELA 


CELA 


CELA 


CELA 


CELA 


322 


340 


470 


255 


235 


9 


17 


CELA 


CELA 


CELA 


CELA 


CELA 


201 


130 


95 


50 


85 


10 


18 


CELA 


CELA 


CELA 


CELA 


CELA 


322 


340 


230 


120 


100 


11 


20 


CELA 


CELA 


CELA 


CELA 


CELA 


60 


55 


55 


80 


50i 


12 


21 


CELA 


CELA 


CELA 


CELA 


CELA 


60 


25 


105 


95 


115 


13 


22 


ARTR 


ARTR 


ARTR 


ARTR 


ARTR 


483 


35 


70 


50 


35 


14 


23 


ARTR 


ARTR 


ARTR 


ARTR 


ARTR 


70 


40 


95 


85 


85 


15 


24 


ARTR 


ARTR 


ARTR 


ARTR 


ARTR 


131 


35 


55 


55 


40 


16 


26 


EXAN 


EXAN 


EXAN 


EXAN 


EXAN 


584 


5 


170 


80 


165 


17 


33 


ARTR 


EXAN 


EXAN 


EXAN 


EXAN 


101 


70 


155 


60 


70 


18 


34 


ARTR 


ARTR 


ARTR 


ARTR 


ARTR 


242 


30 


55 


35 


25 


IS 


35 


ARTR 


EXAN 


EXAN 


EXAN 


EXAN 


322 


120 


195 


25 


135 


20 


50 


ARTR 


EXAN 


EXAN 


EXAN 


EXAN 


393 


105 


115 


60 


70 


21 


51 


ARTR 


EXAN 


EXAN 


EXAN 


EXAN 


111 


45 


30 


50 


45 


22 


53 


ARTR 


ARTR 


ARTR 


ARTR 


ARTR 


121 


15 


15 


20 


15 


23 


54 


EXAN 


EXAN 


EXAN 


EXAN 


EXAN 


201 


15 


30 





0i 


24 


55 


ARTR 


EXAN 


EXAN 


EXAN 


EXAN 


262 


20 


145 


5 


150 


25 


56 


CELA 


CELA 


CELA 


CELA 


CELA 


363 


270 


560 


170 


200 


26 


57 


CELA 


CELA 


CELA 


CELA 


CELA 


201 


180 


330 


170 


230 


27 


121 


ARTR 


ARTR 


ARTR 


ARTR 


ARTR 


121 


170 


110 


80 


115 


282 


122 


ATCO 


EXAN 


EXAN 


EXAN 


ATCO 














25 


29 


123 


ATCO 


EXAN 


EXAN 


EXAN 


EXAN 


20 














30 


124 


ATCO 


EXAN 


EXAN 


EXAN 


EXAN 


20 


25 


15 





5 


312 


125 


ATCO 


EXAN 


EXAN 


EXAN 


ATCO 








10 





30 


32 


126 


ATCO 


EXAN 


EXAN 


EXAN 


EXAN 








5 








33 


127 


ATCO 


EXAN 


EXAN 


EXAN 


EXAN 


252 





15 








34 


128 


ATCO 


EXAN 


EXAN 


EXAN 


EXAN 


50 





15 


30 





35 


147 


ATCO 


EXAN 


EXAN 


EXAN 


EXAN 


101 


5 


30 


15 


5 


36 


148 


ATCO 


EXAN 


EXAN 


EXAN 


EXAN 


50 


5 


10 


5 


5 


37 


149 


ATCO 


ATCO 


ATCO 


ATCO 


ATCO 


111 





5 





10 


38 


150 


ATCO 


EXAN 


EXAN 


EXAN 


EXAN 


10 


5 








5 


3S 


151 


ATCO 


EXAN 


EXAN 


EXAN 


EXAN 

















40 


152 


ATCO 


EXAN 


EXAN 


EXAN 


EXAN 


30 





10 








41 


161 


ATCO 


EXAN 


EXAN 


EXAN 


EXAN 


10 





20 


15 


15 


42 


162 


ATCO 


EXAN 


EXAN 


EXAN 


EXAN 


232 


30 


30 


20 


35 


43 


165 


ARTR 


ARTR 


ARTR 


ARTR 


ARTR 


30 


60 


60 


60 


60 


44 


172 


ATCO 


ATCO 


ATCO 


ATCO 


ATCO 


141 


90 


115 


65 


100 


45 


182 


ATCO 


EXAN 


EXAN 


EXAN 


EXAN 


50 


30 


5 


10 


20 


46 


183 


ATCO 


EXAN 


EXAN 


EXAN 


EXAN 


40 





65 


5 





47 


200 


EXAN 


EXAN 


EXAN 


EXAN 


EXAN 


222 


25 


100 


20 


60 


48 


201 


EXAN 


EXAN 


EXAN 


EXAN 


EXAN 


332 


20 


830 





5 


49 


202 


EXAN 


EXAN 


EXAN 


EXAN 


EXAN 


796 


75 


725 


15 


100 


50 


203 


EXAN 


EXAN 


EXAN 


EXAN 


CELA 


70 


65 


100 


65 


70 


51 


204 


ATCO 


ATCO 


ATCO 


ATCO 


ATCO 


50 


20 


30 


30 


35 


52 


205 


CELA 


CELA 


CELA 


CELA 


CELA 


141 


10 


35 


20 





53 


206 


CELA 


CELA 


CELA 


CELA 


CELA 


81 


15 


55 


25 


25 


54 


207 


ATCO 


ATCO 


ATCO 


ATCO 


ATCO 


60 





30 





10 


Total 


burrow entrances 










10460 


4130 


8105 


3655 


3955 


x burrows /ha 












193.3 


76.5 


150.1 


67.7 


73.2 



1 Change in vegetation classification from previous year. 
2 New transect - couldn't find old post. 



99 



Table 2. Mean number of active Townsend's ground squirrel burrows per hectare 
in the Snake River Birds of Prey Area in 1982 and 1986 - 1989. 
Number of transects in parentheses. 



Vegetation Type 



Active Burrows/ha (# transects) 



1982 



1986 



1987 



1988 



1989 



Ceratoides lanata 
Artemisia tridentata 
Atriplex confertifolia 
Exotic Annuals 



x TGS b/ha 



290.1(16) 

198.9(12) 

61.4(20) 

367.5 (6) 



185.6(16) 
55.0 (7) 
27.5 (4) 
24.6(27) 



290.0(16) 
65.7 (7) 
45.0 (4) 

104.6(27) 



175.3(15) 
56.4 (7) 
23.8 (4) 
19.1(28) 



146.5(17) 
53.6 (7) 
33.3 (6) 
37.1(24) 



193.3(54) 76.5(54) 150.1(54) 67.7(54) 73.2(54) 



Table 3. Number of badger burrows in different vegetation types in the Snake 
River Birds of Prey Area in 1982 and 1986 - 1989. Number of 
transects in parentheses. 



Vegetation Type 



Active Burrows/ha (# transects) 



1982 



1986 



1987 



1988 



1989 



Ceratoides lanata 


119.0(16) 


53.2(16) 


6.9(16) 


19.7(15) 


20.6(17) 


Artemisia tridentata 


62.8(12) 


8.6( 7) 


2.1( 7) 


12. 1( 7) 


3.6 (7) 


Atriplex confertifolia 


9.5(20) 


11. 3( 4) 


2.5( 4) 


5.0( 4) 


1.7 (6) 


Exotic Annuals 


127. 7( 6) 


5.7(27) 


1.3(27) 


2.7(28) 


3.1(24) 


Total # burrows 


3614(54) 


1110(54) 


170(54) 


475(54) 


460(54) 


x Badger b/ha 


66.9 


20.9 


3.1 


8.8 


8.5 



100 



Table 4. Density of active Townsend's ground squirrel burrows on the Black 
Butte burn transects in 1986, 1988, and 1989. Minimum and maximum 
densities per transect in parentheses. 



Burrows per Hectare 
Range Condition* 1986 1988 1989 



Control 36.3 (20-60) 50.0 (20-85) 70.0 (30-110) 

Partial Burn 23.8 (5-40) 10.0 (0-35) 51.3 (0-80) 

Burn/Reseeded 8.8 (5-20) 8.8 (0-25) 18.8 (0-60) 

Burn/No Treatment 11.3 (0-35) 0.0 (0-0) 25.0 (0-70) 



x Four transects per range condition 



Total 20.0 17.2 41.3 



101 



Table 5. Active Townsend's ground squirrel and badger 

burrow densities in range seedings, 1987 - 1989 
( 1 1 transects ) . 



Transect 
Number 



1003 
1005 
1010 

x b/ha 



1985 
1985 
1981 



TGS 
burrows /ha 



1987 1988 1989 



Gl 


1986 


60 


125 


G2 


1986 


15 


100 


G3 


1983 


85 


90 


G4 


1983 


175 


60 


G5 


1986 


65 


15 


G6 


1986 


85 


35 


1001 


1985 


55 


15 


1002 


1985 


15 








10 





15 



180 175 



5 
45 
60 
60 

20 
40 
10 
10 
15 
5 
135 



Badger 
burrows /ha 



1987 1988 1989 



5 


20 








85 


15 





20 


5 





10 








10 





15 


15 


5 


5 





























5 








30 


10 



67.7 57.3 36.8 



3.1 17.7 3.2 



102 



PLANS FOR NEXT YEAR 

The 81 transects will be monitored in 1990 as in past years. In 
addition, a pilot study will be initiated to validate hole count procedures 
and to test for variability among transects. 



LITERATURE CITED 

Daubenmire, R. A. 1959. A canopy coverage method of vegetational analysis. 
Northwest Sci. 33:43-64. 

Groves, C. R. , and K. Steenhof. 1988. Responses of small mammals and 
vegetation to wildfire in shadscale communities of southwestern Idaho. 
Northwest Sci. 62:205-210. 

Johnson, D. R. , N. C. Nydegger, R. Feldman, S. S. Sundseth, and D. L. 

Yensen. 1982. Abundance and demography of prey populations in the Snake 
River Birds of Prey Area. Pages 20-37 in Snake River Birds of Prey 
Research Project Annual Report. U.S. Dep. Inter. 53pp. 

Nydegger, N. C, and G. W. Smith. 1986. Prey populations in relation to 
Artemesia vegetation types in southwestern Idaho. Pages 152-156 in E. D. 
McArthur and B. L. Welch, eds. Proceedings — Symposium on the biology of 
Artemisia and Chrysothamnus . Gen. Tech. Rep. INT-200, U.S. Dept. Agric, 
For. Serv., Intermountain Res. Sta. , Ogden, Utah. 389pp. 

Peterson, K. , and E. Yensen. 1986. Comparison of 1982 and 1986 Townsend's 
ground squirrel burrow entrance transects in the Snake River Birds of 
Prey Area, southwestern Idaho. Pages 152-168 in K. Steenhof and M.N. 
Kochert, eds. U.S. Dep. Inter. Snake River birds of prey research 
project annual report. 172pp. 

Smith, G. W. , and D. R. Johnson. 1985. Demography of a Townsend ground 
squirrel population in southwestern Idaho. Ecology 66:171-178. 

Timmerman, K. , K. Steenhof, J. Weaver, and R. Gerber. 1988. Townsend's 
ground squirrel food habits and relative abundance in the Snake River 
Birds of Prey Area. Pages 100-121 in K. Steenhof, ed. , Snake River Birds 
of Prey Area 1988 Annual Report. 

U.S. Department of the Interior. 1979. Snake River Birds of Prey Special 
Research Report. Bur. Land Manage., Boise District, Idaho. 141pp. 



103 



TITLE: Townsend's Ground Squirrel Diets in the Snake River Birds of Prey 
Area. 

INVESTIGATOR: Eric Yensen, Department of Biology, The College of Idaho 

00OPERATORS: The College of Idaho 

Boise State University 

OBJECTIVE: To investigate the food habits of the Townsend's ground squirrel 
in burned and unburned, seeded and unseeded big 
sagebrush/winterfat mosaic habitats in the Snake River Birds of 
Prey Area. 



INTRODUCTION 

Townsend's ground squirrels ( Spermophilus townsendii ) are important prey of 
raptors in the Snake River Birds of Prey Area (U.S. Dep. of Inter. 1979). 
Continued existence of dense breeding populations of raptors depends upon 
maintenance of Townsend's ground squirrel (TGS) populations. Recent 
fire-induced vegetation changes in the Snake River Birds of Prey Area have 
resulted in the replacement of native shrub and bunchgrass-dominated communities 
by exotic annual-dominated communities (Yensen 1980, Kochert and Pellant 1986). 
Townsend's ground squirrel burrow count transects have indicated that TGS 
populations are much less stable in exotic annual -dominated communities (Yensen 
et al. in prep.). Consequently, it is important to gather base-line data on TGS 
diets and to determine if these exotic species will meet the nutritional 
requirements of Townsend's ground squirrels. 

Howell (1938), Davis (1939a), Davis (1939b), Alcorn (1940), Johnson (1961), 
Johnson et al. (1977), Johnson et al. (1978), Rogers and Gano (1980), Johnson 
(1980), Rickart (1982a), Rickart (1982b), and Smith and Johnson (1985) have 
reported on TGS food habits in varying amounts of detail. However, information 
on TGS food habits in southwestern Idaho sufficient to predict their response to 
a diet of exotic annuals is needed. As a step toward that goal, this study was 
designed to collect data on diets of Townsend's ground squirrels in the Snake 
River Birds of Prey Area. 

Dietary analysis using Sparks and Malechek's (1968) microhistological 
technique is well-established and widely used (review in Holechek et al. 1982). 
There is considerable information on the accuracy of the technique, but the 
precision of the dietary estimates has received relatively little attention 
(Holechek et al. 1982). Since the technique estimates the contents of a TGS 
stomach (10-20 cc) from a series of microscopic fields several orders of 
magnitude smaller, both the accuracy and precision of the sampling scheme are of 
interest. A secondary goal of this study was to estimate the accuracy and 
precision of the Townsend's ground squirrel food habits data. 



METHODS 

Vegetation analysis (Daubenmire 1959) was conducted at each site in early 
June 1987 and late May 1988 while TGS were being collected. Percent cover and % 
frequency were determined for each plant species at each site. 



104 



Study Areas 

Townsend's ground squirrels were collected for stomach contents analysis at 
4 sites in the Snake River Birds of Prey Area by Bureau of Land Management 
personnel. The sites are located near Coyote Butte, approximately 19 km south 
of Kuna, Ada Co., Idaho. 

Site 1, native grass. This site is a burned big sagebrush ( Artemisia 
tridentata ) -winterf at ( Ceratoides lanata) community now dominated by remnant 
native Sandberg's bluegrass (Poa secunda ) . six-weeks fescue (Vulpia octoflpra), 
and squirrel tail (Sitanion hystrix ). but it has been invaded by tumbleweed 
( Salsola lberica), cheatgrass ( Bromus tectorum), and other exotic annuals 
(Tables 1 and 2). 

Site 2, exotic annuals. This site is adjacent to Site 1, and was similar 
to it prior to the burn. However, it is now dominated by cheatgrass and tumble 
mustard (Sisymbrium altissimum ) , with some remnant native grasses, especially 
Sandberg's bluegrass. 

Site 3, big sagebrush. This site is <1 km southeast of Site 2 and is in a 
big sagebrush-winterfat mosaic, representing the unburned condition of Sites 1 
and 2. Big sagebrush, winterf at, and native grasses (Sandberg's bluegrass, 
squirreltail, six-weeks fescue) dominate the site; cheatgrass is the main exotic 
annual. 

Site 4, rehabilitation seeding. This former big sage-winterfat mosiac is 
located 6 km east, 2.5 km south of Site 3. The area burned and was subsequently 
reseeded with desert wheatgrass ( Agropyron desertorum) in 1981. The area is 
currently dominated by Sandberg's bluegrass, desert wheatgrass, tumbleweed, and 
other native and exotic forbs. 

Diet Analysis 

Squirrels were collected by BLM personnel at all 4 sites in May and June of 
1987 (n = 75) and in March and May of 1988 (n = 42) by trapping and shooting, 
except no squirrels were collected from Site 4 in May 1988. Squirrels were aged 
in the field using body weight criteria (Bureau Land Management, unpubl. data). 
Selected specimens were prepared as standard study skins with skulls and 
deposited in the College of Idaho Museum of Natural History. Examination of 
tooth wear patterns confirmed the age assignments. The 1987 specimens were 
collected late in the active season while the adults were entering seasonal 
torpor and all were juveniles; all 1988 specimens were either yearlings or 
adults . 

Stomachs were removed from the animals immediately post-mortem and 
preserved in 70% ethanol. In the lab, stomach contents were removed from 
ethanol, diluted 50% with water, and homogenized 1 min in a Waring blender to 
produce fragments of uniform size. The homogenate was washed through a 1-mm 
sieve (Hansen 1978) and collected in a 0.1-mm screen to remove tiny, 
unidentifiable fragments. The material was then mounted on microscope slides 
using Hertwig's and Hoyer's media (Sparks and Malechek 1968). 



105 



Plant species in the diet were identified by comparisons to a reference 
collection of microscope slides using microhistological characters. All 
reference slides were made from catalogued specimens in the College of Idaho 
Harold M. Tucker Herbarium and were prepared using the technique described 
above. 

For food habits analysis, one slide was examined per stomach. Occurrence 
of food categories (frequency) was recorded from each of 20 microscope fields 
per slide using a phase-contrast microscope at 100X. Frequency/20 fields was 
then converted to percent relative density (Sparks and Malechek 1968) using a 
table developed for frequency-to-density conversion (Fracker and Brischle 1944). 

Three measures of a dietary category's importance in TGS diets were used: 
1) Percent relative density as described above was a dry weight conversion from 
frequency data. 2) Percent frequency in stomachs was simply the percentage of 
stomachs from a site with the item. 3) Percent frequency in microscopic fields 
was the percentage of all the microscopic fields from a site with the item. 

ACCURACY AND PRECISION OF THE DIETARY ANALYSIS 

Eight stomachs were randomly selected from the stomachs collected in 1987 
and 1988. Ten slides were prepared from each of these stomachs using the 
techniques described above. Three test mixtures were made from known weights of 
various mixtures of species occurring in the study areas. Twenty microscopic 
fields were examined from each slide using a pre-determined pattern, and 
frequency of occurrence of each species was recorded. 

The frequency of each dietary category/20 fields on 1 slide was compared to 
other slides (or replicate counts of the same slide) using the Kulcyznski Index 
(Oosting 1956) (also well known as the "Bray-Curtis" similarity index [Bray and 
Curtis 1957]), 

2w/(a + b) 

The index was calculated as a dissimilarity index, 

1 - [2w/(a + b)] 

using a BASIC microcomputer program provided by Ludwig and Reynolds (1988) and 
converted to similarity when that was of interest. 



Intra-slide Variation 

Twenty is a convenient number of fields to locate on a standard microscope 
slide, either randomly or using a predetermined search pattern. Holechek and 
Vavra (1981) used correlations to show that more than 20-24 fields/slide did not 
improve accuracy of the estimate, but fewer than 20 fields/slide gave poor 
results. Consequently, they recommended 20 fields/slide. 

What level of precision is associated with 20 fields/slide? Three slides 
were randomly selected, and 20 fields were recorded. This procedure was 
replicated 6 times for each slide, and the similarities of the frequency data 
from each replication were compared. Mean similarities between replicates were 

106 



88% (range = 83-93%) for the 3 slides. The mean standard deviation within 
slides was 2.09. Thus a given slide will be read with about 88% precision at 20 
fields/slide . 

Inter-slide variation 

For this analysis, 10 slides each were made from stomachs 1987-14, 1987-16, 
1988-4, and test mixture "A," and 20 fields were read from each slide. There 
are 45 possible comparisons of 10 slides from a given stomach. Mean 
between-slide similarities were 87.0% (s = 5.7), 86.6% (s = 7.3), 87.0 (s = 
4.1), and 88.6% (s = 3.3), respectively for the 3 stomachs and test mixture. 
Thus, there is approximately 87% precision from 1 slide to another prepared from 
a single stomach when 20 fields per slide are examined. This is not appreciably 
different from the precision of replicate readings of the same slide. I 
interpret this as meaning that the food particles in the samples were well mixed 
and that the variation in readings was due to sampling error resulting from the 
number of fields examined, rather than differences in distribution of food items 
among slides from a given stomach. 

How many slides constitute an adequate sample? 

Running means of the frequency of each species were calculated as the 
number of slides from a stomach increased from 2 to 10. Kulcyznski's Index was 
calculated for similarities among cumulative means at each increase in sample 

size. 

For stomach #1988-4, similarity values among running means increased from a 
mean of 89.1% (2 slides per stomach) to 94.7% (3 slides) to 97.4% (4 slides) to 
98.7% (5 slides) and then went asymptotic, finally reaching 99.0% (8-10 
slides). Test mixture "A" with only 3 species increased from a mean of 91.5% (2 
slides/stomach) to 97.3% (3 slides), then went asymptotic. Two other samples 
(#1987-14 and #1987-16) followed intermediate patterns. 

Holechek and Vavra (1981:338) found using a correlation approach that "Nine 
slides per sample would estimate all major species in the diet within 10% of the 
mean at the 95% confidence level. However, 60 slides per sample would be 
required for minor species and 156 slides for trace species to achieve this 
level of precision." However, for species that comprise >30% of the diet, 1 
slide will yield this level of precision. 

My results suggest that mean frequencies will become relatively stable 
after counting 5 slides with 20 fields/slide, but that the means should change 
<5% after the 3rd slide. These samples contained only a few common species and 
thus fewer than 5 slides were required for relatively precise estimates. 
Because of the small number of relatively abundant species in TGS diets in the 
Snake River Birds of Prey Area, a relatively low number of slides yields 
acceptably precise estimates of diet. 

The level of precision in a given study will be a compromise between the 
precision needed for the purposes of the study and the economic cost of 
attaining that precision. For purposes of a diet survey such as this, 1 slide 
per stomach is adequate to show general trends. For a detailed analysis in a 



107 



well-controlled study, the increased precision gained from examining 5 slides 
per stomach will be desired. Future emphasis should also focus on sampling more 
stomachs (or fecal pellets), since a stomach equals 1 meal only. 

The data reported below will have ca. 10% error in precision. Thus for 
example, 39% relative density of Bromus tectorum in Table 6 will imply a true 
value between 35-43%. 



Accuracy 

Since only frequency is recorded in reading slides (presence or absence of 
a species in a microscope field) , error results from incorrect recognition of a 
fragment or error in deciding whether enough of a species is present to count 
it. Not every fragment will be recognizable. The major problem involves 
species that are easy to recognize, since they will be overrepresented. 

Accuracy in microhistological diet analysis technique is gained by 
utilizing test slides (Holechek and Gross 1982). Slides are prepared using 
known mixtures of plant tissue, then the slide is counted and the results are 
compared to the known frequencies. Counting techniques are then adjusted on a 
trial and error basis until good results are consistently obtained. 

There are 5 major sources of error: 

1. Forbs with numerous, easily recognized trichomes (especially winterfat) tend 
to be overrepresented. 

2. Easily recognized grasses (especially cheatgrass) also tend to be 
overrepresented . 

3. Conversely, plants with few distinctive features tend to be underrepresented 
in the counts. 

4. Plants which fragment easily are overrepresented in microscope fields. 

5. More digestable shrub and forb species will be underrepresented while 
grasses will be overestimated (Vavra and Holechek 1980, Samuel and Howard 
1983). 

Vavra and Holechek (1980) found actual and estimated dietary frequencies 
could vary significantly due to differential digestibility and/or partial 
destruction of plant tissue in slide preparation. They recommended the use of 
correction factors to compensate for these errors (cf. Leslie et al. 1983). 
Others (Holechek and Gross 1982) advocate the use of "counting rules" and test 
slides ( ignoring trichomes on certain species , etc . ) as the most efficient way 
to compensate. 

In this study, I used "counting rules" to minimize over- or 
underestimation. Use of test mixtures indicated an additional 5% error 
(Bray-Curtis dissimilarity) in the results reported below, mostly due to 
overrepresentation of cheatgrass and winterfat. Total error (precision plus 
accuracy) is thus estimated at 10-15%. 



108 



RESULTS 

Results of the vegetation analysis (% cover and % frequency) are shown in 
•+iTv i Percent cover was converted to % relative cover and averaged 
•r 1 £T e< l uenc y to Sive an importance value for each plant species at each 
site. There was variation in % cover, % frequency, and importance values of the 
species at a site between years. Importance values averaged only 65% similar 
(range 48-77%) at a site between years, using the Kulcyznski Index. Total % 
?° V ™ decr ^ ased « a11 sites in 1988. The similarity among the 4 sites averaged 
48.7/o similarity (range 27-73%) in 1987. Site 3 (unburned sagebrush "control") 
was most similar (60%) to Site 1 (native grasses), and less similar to Sites 2 
and 4 (burn and seeding, 44 and 47%, respectively). In 1988, when there was 
aT^J^ rbaceous cover ' the sites were slightly more similar (mean = 61.3%, range 
47-74%) . Thus the sites differed in floristic composition almost as much 
between years as between each other. 

Although the 3 measures of dietary importance (% relative density (= % dry 
weight), % frequency in stomachs, % frequency in fields) gave different 
numerical results, the rank orders among categories were generally consistent 
(Tables 3-8). However, % frequency in stomachs (Tables 4 and 7) was very 
sensitive to small sample sizes. 

I found 1-9 food categories per stomach. Site means varied from 3.8 to 4.4 
categories per stomach. The total number of food categories used by all TGS 
sampled at a site varied from 4-17 on the 3 sampling occasions (May- June 1987, 
March 1988, May 1988). However, if species used in trace amounts are 
eliminated, only 4-10 categories were used. Furthermore, at each site only 2-4 
species comprised >10% relative density in the diet. Species comprising >10% of 
the diet at 1 or more study sites included cheatgrass, Sandberg's bluegrass, 
six-weeks fescue, winterfat, big sagebrush, tumbleweed, Descurainia spp. , seeds 
of bur buttercup ( Ranunculus testiculatus ) . and insects. 

Grasses were important constituents of the diet in both 1987 and 1988, and 
often comprised over 50% of the diet (37-88% relative density, Tables 3 and 6). 
Cheatgrass and Sandberg's bluegrass were both heavily utilized, especially in 
March 1988 (55-87% of diet). Late in the TGS active season (May and June) use 
of grasses declined (except Site 2 in 1988). Most of the grass eaten in 
May- June consisted of seeds, especially of cheatgrass. Sandberg's bluegrass 
leaves were utilized slightly more than cheatgrass leaves (Tables 6-8, March) 
and the 2 together were far more important than all other grasses combined. 
Interestingly, squirreltail was little used, although it was the third most 
abundant grass. 

Winterfat (0-43% relative density) and big sagebrush (0-21%) were both 
eaten, and winterfat was especially important at Site 3 where it was most 
abundant. Winterfat was utilized at all sites in 1987, even though it was not 
abundant enough to be sampled by the vegetation analysis in some cases. It was 

Sfi 2 at Site 3 in 1988, and its use decline d between March and May 1988 
(Tables 7 and 8). Big sagebrush was used in March at all sites in both years, 
but was less important in May. 

Tumbleweed and tumblemustard were the most important forb species 
consumed. Tansymustards ( Descurainia sophia and D. pinnata ) . peppergrass 
(L epidium perfoliate ) , seeds of bur buttercup, and leaves of prickly lettuce 

109 



Table 1. Vegetation cover and frequency in May 1987 at 4 study sites 
near Coyote Butte in the Snake River Birds of Prey Area, 
southwestern Idaho. Data are from 40 1-m* quadrats 
(Daubenraire transect) per site. Abbreviations: %C = percent 
cover, %F = percent frequency, "tr" = <0.1%, dash = not 
present . 



Species 


Site 
%C 


1 
%F 


Site 
%C 


2 
%F 


Site 
%C 


3 

%F 


Site 
%C 


4 
%F 


GRASSES 


















Bromus tectorum 


0.4 


20 


14.6 


100 


2.0 


43 


_-_— 




Poa secunda 


21.9 


95 


3.9 


70 


13.7 


S5 


13.9 


93 
15 


Vulpia octof lora 


1.2 


43 


tr 


3 


0.3 


3G 


1.4 


Sitanion hystrix 


1.2 


23 


0.3 


15 


0.7 


30 


1.0 


53 


Agropyron desertorum 


""" 


~~ 










SHRUBS 


















Ceratoides lanata 


0.1 


5 





— 


7.0 


38 


1.1 


8 


Artemisia tridentata 





— 


■■* — ~~ 


~ — 


11.6 


33 






PORBS 


















Salsola iberica 


0.8 


63 





— 


_- -— 


— _ 


1.0 


10 


Descurainia sophia 


0.1 


5 





— 


__— 


__ 






Sisymbrium altissimum 


0.2 


15 


1.8 


58 


_» — 


mmmm 


tr 


3 


Lactuca serriola 





— 





— .— 


■"*" 




"other forbs" 





— 








tr 


3 






TOTAL COVER (%) 


25.9 




20.6 




35.3 




18.4 





110 



Table 2. Vegetation cover and frequency in May 1988 at 4 study sites 
near Coyote Butte in the Snake River Birds of Prey Area, 
southwestern Idaho. Data are from 40 1-m 2 quadrats 
(Daubenmire transect) per site. Abbreviations: %C = percent 
cover, %F = percent frequency, "tr" = <0.1%, dash = not 
present . 



Species 


Site 


1 


Site 


2 


Site 


3 


Site 


4 




%C 


%F 


%C 


%F 


%C 


%F 


%C 


%F 


GRASSES 


















Bromus tectorum 


3.8 


40 


1.6 


55 


0.3 


3 


2.9 


40 


Poa secunda 


5.8 


75 


3.6 


60 


6.2 


93 


5.4 


80 


Vulpia octoflora 





— 


0.3 


15 


0.2 


13 


0.1 


5 


Sitanion hystrix 


1.2 


20 


2.9 


28 


0.8 


18 


3.6 


50 


Agropyron desertorum 





— 





— 





— 


tr 


3 


SHRUBS 


















Ceratoides lanata 


0.3 


8 





— 


7.2 


63 





—MM 


Artemisia tridentata 





— 


0.8 


3 


8.8 


40 


_ — — 





Atriplex nuttallii 





— 





— 





— 


1.5 


28 


PORBS 


















Salsola iberica 


0.9 


45 


0.1 


3 


___ 


__ 


0.4 


33 


Descurainia sophia 





— 





— 


__ _ 





— _— 





Sisymbrium altissimum 


1.8 


50 


0.8 


23 


0.4 


20 


0.1 


8 


Lactuca serriola 





— 





— — 








— —. 


auj 


"other forbs" 


0.7 


13 


0.1 


3 


0.1 


10 


tr 


3 


TOTAL COVER (%) 


14.5 




10.2 




24.0 




14.0 





111 



Table 3. Late season (25 May- 19 June 1987) percent relative 
density of dietary categories in juvenile 
Townsend's ground squirrel stomachs at 4 sites in 
the Snake River Birds of Prey Area. Adults were 
entering torpor and none were collected during this 
period. A dash indicates the species was not 
recorded, "tr" indicates <1%, and n s number of 
stomachs . 



Food Item 



Site 1 Site 2 Site 3 Site 4 



21 



20 



15 



IS 



GRASSES 










Bromus tectorum 


22 


62 


31 


57 


Poa secunda 


24 


tr 


7 


tr 


Sitanion hystrix 


tr 


— 


tr 


— 


Oryzopsis hymenoides 


— 


tr 


— 


— 


grass seed 


tr 


tr 


tr 


— 


grass root? 


2 


tr 


tr 


— 


Total grasses 


49 


64 


39 


57 


SHRUBS 










Ceratoides lanata 


3 


4 


43 


11 


Artemisia tridentata 


tr 


1 


6 


tr 


Atriplex nuttallii 


— 


tr 


2 


4 


Chrysothamnus viscidiflorus 


— 


— 


— 


tr 


Total shrubs 


3 


5 


51 


16 


PORBS 










Salsola iberica 


39 


3 


1 


7 


Sisymbrium altissimum 


tr 


5 


— 


2 


Descurainia - 2 spp. 


tr 


tr 


— 


— 


Lepidium perfoliatum 


— 


2 


tr 


1 


Cryptantha interrupta 


tr 


— 


— 


— 


Ranunculus testiculatus 


tr 


— 


— 


— 


Lactuca serriola 


— 


1 


— 


2 


Chenopodiaceae 


— 


tr 


tr 


tr 


forb 


— 


— 


— 


6 


Total forbs 


40 


11 


2 


18 


MISC. 










insects 


8 


19 


7 


3 


fungi 


— 


1 


tr 


tr 


unknown 


tr 


— 


tr 


4 


seed 


tr 


tr 


— 


— 


Total misc. 


8 


20 


8 


8 



112 



Table 4. Percent of stomachs containing a dietary category 
in 1987. Samples of juvenile Townsend's ground 
squirrels were collected late in the active season 
(25 May- 19 June) at 4 sites in the Snake River 
Birds of Prey Area. Adults were entering torpor 
and none were collected during this period. A dash 
indicates the dietary category was not recorded at 
the site during the sampling period; n = number of 
stomachs . 



Food Item 



Site 1 Site 2 Site 3 Site 4 



n 



21 



20 



15 



19 



GRASSES 

Bromus tectorum 

Poa secunda 

Sitanion hystrix 

Oryzopsis hymenoides 

grass seed 

grass root? 

SHRUBS 

Ceratoides lanata 
Artemisia tridentata 
Atriplex nuttallii 
Chrysothamnus viscidiflorus 



71 


100 


87 


95 


86 


25 


40 


11 


10 


— 


13 


— 


— 


5 


— 





19 


5 


13 


__ 


10 


5 


13 


— 


52 


10 


67 


32 


14 


10 


67 


5 


— 


5 


13 


37 


— 


— 


— 


5 



FORBS 

Salsola iberica 

Sisymbrium altissimum 

Descurainia - 2 spp. 

Lepidium perfoliatum 

Cryptantha interrupta 

Ranunculus testiculatus 

Lactuca serriola 

Chenopodiaceae 

forb 



91 



40 



5 


60 


4 


5 


— 


20 


5 


— 


5 


— 


- 


25 


- 


5 



20 



13 



63 

21 



2! 



5 
21 

11 



MISC. 

insects 

fungi 

unknown 

seed 



62 

5 

5 



90 
10 



87 
7 

7 



53 
5 
5 



113 



Table 5. Percent of microscope fields containing each 

dietary category in 1987. Samples of juvenile 
Townsend's ground squirrels were collected late in 
the active season (25 May-19 June) at 4 sites in 
the Snake River Birds of Prey Area. Adults were 
entering torpor and none were collected during this 
period. A dash indicates the dietary category was 
not recorded at the site during the sampling 
period; n = total microscope fields. 



Food Item Site 1 Site 2 Site 3 Site 4 



n 



420 400 300 380 



CLASSES 










Bromus tectorum 


41 


93 


45 


74 


Poa secunda 


35 


2 


S 


tr 


Sitanion hystrix 


2 


— 


tr 





Oryzopsis hymenoides 


— 


tr 


~— - 


~~— ' 


grass seed 


5 


1 


1 


_— 


grass root? 


9 


2 


3 




SHRUBS 










Ceratoides lanata 


9 


5 


53 


17 


Artemisia tridentata 


2 


3 


13 


2 


Atriplex nuttallii 


— 


tr 


5 


12 


Chrysothamnus viscidiflorus 


— 


~ ~" 


" 


2 


FORBS 










Salsola iberica 


63 


tr 


3 


17 


Sisymbrium altissimum 


tr 


19 


— 


5 


Descurainia - 2 spp. 


2 


tr 


— 


■"" 


Lepidium perfoliatum 


— 


S 


1 


3 


Crvntantha interrupta 


tr 


— 


«._ 


"" 


Ranunculus testiculatus 


1 


— 


— - 


— ~ 


Lactuca serriola 


— 


5 


— 


4 


Chenopodiaceae 


— 


tr 


tr 


2 


forb 


— 


_— 


" 


7 


MISC. 










insects 


17 


44 


21 


11 


fungi 


— 


4 


1 


2 


unknown 


tr 


— 


4 


5 


seed 


1 


tr 







114 



Table 6. Percent relative density of dietary categories in Townsend's 
ground squirrel stomachs at 4 sites in the Snake River Birds 
of Prey Area in 1988. Site 4 was not sampled in May. A 
dash indicates the species was not recorded; "tr" indicates 
<1%. 



Species Site 1 Site 2 Site 3 Site 4 

Mar May Mar May Mar May Mar 



n 415574 16 

GRASSES 
Poa secunda 
Bromus tectorum 
Vulpia octoflora 
Sitanion hystrix 
Agropyron desertorum 
grass seed 
grass root 

Total grasses 87 57 83 88 55 37 79 

SHRUBS 

Ceratoides lanata — — — — 24 13 

Artemisia tridentata 11 — 15 — 21 3 3 

Atriplex nuttallii — 3 — 6 2 3 

Chrysothamnus viscid if 1 . — — — — tr 



48 


2 


67 


19 


51 


— 


39 


39 


22 


16 


35 


4 


24 


39 


tr 


29 


— 


21 


— 


6 


tr 


— 


1 


— 


4 


tr 


5 


— 


— 


1 










1 


— 


2 


— 


4 


— 


2 


— 


"~~ — 


~~ 


— 


5 









Total shrubs 11 3 15 6 45 18 6 

PORBS 

Salsola iberica — 22 

Sisymbrium altissimum — — 1 6 tr 1 2 

Descurania spp. 2 — — 15 \o 

Ranunculus testiculatus — 17 — — 28 

Cryptantha interrupta — — — — __ 2 

Halogeton glomeratus — — — \ 

Lepidium perfoliatum ? — — — tr 

Crepis accuminata ? — — — tr 

Lactuca serriola ? — — tr 

Chenopodiaceae 

forb root — — tr 



Total misc. tr 



tr 



Total forbs 2 39 1 6 tr 44 15 

MISC. 

insect — — tr 

unknown plants — — — tr 



115 



Table 7. Percent of Townsend's ground squirrel stomachs containing a 
dietary category. Specimens collected at 4 sites in the 
Snake River Birds of Prey Area in March and May 1988. Site 
4 was not sampled in May. A dash indicates the dietary 
category was not found in stomachs at the site during the 
sampling period. 



Species Site 1 Site 2 Site 3 Site 4 

Mar May Mar May Mar May Mar 



n 



16 



GRASSES 
















Poa secunda 


100 


100 


100 


80 


100 





100 


Bromus tectorum 


75 


100 


100 


80 


71 


75 


100 


Vulpia octoflora 


25 


100 





100 





100 


6 


Sitanion hystrix 





100 


— 


40 


14 


50 





Agropyron desertorum 





100 














13 


grass seed 





100 


— 


20 





25 





grass root 











60 











SHRUBS 
















Ceratoides lanata 














86 


50 





Artemisia tridentata 


50 





60 





100 


50 


13 


Atriplex nuttallii 





100 





20 





25 


19 


Chrysothamnus viscid. 

















tr 





PORBS 
















Salsola iberica 





100 

















Sisymbrium altissimum 








20 


60 


14 


75 


56 


Descurania spp. 


25 














50 


75 


Ranunculus testiculatus 





100 











50 





Cryptantha interrupta 





— 














13 


Halogeton glomeratus 




















13 


Lepidium perfoliatum? 





— 


— 











6 


Crepis accuminata? 








— 











6 


Lactuca serriola? 




















6 


Chenopodiaceae 




















13 


f orb root 











20 











MISC. 
















insect 

















25 





unknown plants 

















25 






116 



Table 8. Percent of microscope fields containing each dietary- 
category in 1988. Specimens collected at 4 sites in the 
Snake River Birds of Prey Area in March and May 1988. Site 
4 was not sampled in May. A dash indicates the dietary 
category was not recorded at the site during the sampling 
period; n = total microscope fields. 



Species Site 1 Site 2 Site 3 Site 4 

Mar May Mar May Mar May Mar 



n 80 20 100 100 140 80 320 



GRASSES 
















Poa secunda 


73 


10 


92 


40 


86 


_ _ 


71 


Bromus tectorum 


35 


S5 


46 


57 


16 


34 


70 


Vulpia octoflora 


1 


75 


— 


36 


— 


18 


tr 


Sitanion hystrix 


— 


5 


— 


6 


1 


18 





Agropyron desertorum 


— 


5 










1 


grass seed 


— 


10 


— 


10 





1 





grass root 


— 


— 


— 


13 


— 









SHRUBS 

Ceratoides lanata — — — — 55 25 

Artemisia tridentata 41 — 35 — 46 8 6 

Atriplex nuttallii — 15 — 14 — 4 8 

Chrysothamnus viscid . — — — — — 1 

FORBS 

Salsola iberica — 60 

Sisymbrium altissimum — — 5 18 14 4 

Descurania spp. 6 — — — 33 25 

Ranunculus testiculatus — 55 — — — 43 

Cryptantha interrupta — — — — — 4 

Halogeton glomeratus — — — — 7 

Lepidium perfoliatum ? — — — — — tr 

Crepis acuminata? — — — — tr 

Lactuca serriola ? — — — tr 

Chenopodiaceae — — — tr 

forb root — — — 1 

MISC. 

insect — — ± 

unknown plants — — — 7 



117 



(Lactuca serriola ) were of secondary importance. All of these are introduced 
annuals. Common cryptantha ( Cryptantha intermedia ) was the only native forb 
found in TGS stomachs. The importance of forbs in the diet increased between 
March and May 1988, while the percentage of grasses and shrubs decreased (Table 
6). 

A surprising number of insects were eaten, especially in May- June 1987 
(11-44% of microscope fields, Table 5). However, insects were not important in 
1988 (1% of microscope fields at Site 3 only, Table 8). Insect remains were so 
fragmentary that identification was not usually possible. However, abundant 
lepidoptera larvae could be recognized by the soft exoskeleton and prolegs, and 
recognizable fragments of beetle antennae and elytra were found. 

The 1988 sampling indicated large differences between March and May diets 
(Tables 6-8). Percent relative densities of dietary categories (Table 6) at 
Sites 1, 2, and 3 were only 24%, 36%, and 20% similar, respectively, between 
March and May, indicating a strong seasonal component in TGS diets. 

In 1987, diets were 47% (range 36-73%, s = 13.8%) similar between sites. 
Diets were most similar at Sites 2 and 4. Site 1 diets were least similar to 
the other sites (37%, 41%, 36% similarity with Sites 2, 3, and 4, 
respectively). In March 1988, TGS diets averaged 65% (range 40-75%, s = 15%) 
similarity among all sites. By May 1988, TGS diets averaged only 47% (range = 
39-51%, s = 7%) similarity among all sites. This decrease in similarity between 
March and May corresponds to decreasing importance of grasses and increasing use 
of other food categories. 

Between-year dietary similarity was 47%, 40%, and 43% at SiteB 1, 2, and 3, 
respectively, using the May-June 1987 and May 1988 stomachs. At these sample 
sizes, differences between years at 1 site were approximately as large as 
differences between sites in a given year. 

DISCUSSION 

Both the vegetation and TGS diets vary nearly as much between years as 
among sites. However, the reasons for between-year differences in vegetation 
importance values at a site are not clear. This could be the result of 1) less 
September-May precipitation (192 mm vs. 170 mm in 1986-7 and 1987-8, 
respectively, at Kuna ca. 20 km N), or 2) differences in timing of precipitation 
(no fall rains in 1987), but possibly 3) the result of differences in observer 
subjectivity in the Daubenmire technique, or 4) spatial heterogeneity in 
vegetation. The Daubenmire quadrats were taken on the same transect in both 
years by technicians with the same training. Consequently, differences in 
amount and timing of precipitation are the most likely factors. 

The substantial annual differences in TGS diets may be the result of 1) 
vegetation differences between years, 2) the fact that juveniles were sampled in 
1987 and adults and yearlings were collected in 1988, or 3) differences in 
collecting dates (25 May-19 June 1987 and 16-19 May 1988). 

The differences in age classes are probably not important. Fitch (1948) 
found no differences in adult and juvenile diets in California ground squirrels 
(S. beecheyi ) and Dyni and Yensen (in prep.) found no dietary differences 
between adult/yearling and juvenile Idaho (S. brunneus ) and Columbian (S. 



118 



columbianus ) ground squirrels. Hansen and Johnson (1976) found no differences 
in elegant (S. elegans ) ground squirrel diets by sex or age class. On the other 
hand, the 1988 data do show a strong seasonal component. Thus, the observed 
annual dietary differences are probably a result of later collecting dates in 
1987, combined with annual vegetation differences. 

At each site, several plant species were found in TGS stomachs that did not 
appear in the vegetation analysis for that site. The Daubenmire (1959) method 
of vegetation analysis gave an intuitively acceptable estimate of dominant 
vegetation, but for establishing a close link between plant abundance and 
herbivore diets, a finer scale method of resource analysis will be necessary. 
For example, the Daubenmire method used a single transect with 40 1-m 2 
quadrats at each site. However, individual TGS have large home ranges (mean = 
1357 m 2 , Smith and Johnson 1985). Given the heterogeneous nature of 
vegetation and the wide foraging radius of individual TGS, it is not surprising 
that TGS were eating species not recorded by the vegetation analysis. 

Although halogeton ( Halogeton glomeratus ) was not recorded by the 
vegetation analysis, small amounts of it were found in 2 stomachs at Site 4 in 
March 1988 (Tables 6-8) . Halogeton is poisonous to livestock, but sheep can eat 
it with impunity in winter, probably because rains have leached the oxalates out 
of the dried leaves (Cook 1977). Presumably, TGS were eating dried, rather than 
fresh, leaves in March. 

Johnson, et al. (1977) reported that Townsend's ground squirrels in the 
Snake River Birds of Prey Area ate cheat grass preferentially, and Sandberg's 
bluegrass received little use. This study found that both grass species were 
heavily used, especially in March. This discrepancy could either be the result 
of the methods used (microscopic examination vs. field observations), site 
differences, or the result of annual variation in TGS diets. 

The number of plant species in the diet not recorded by the vegetation 
analysis precluded determining dietary preference indices for TGS. However, 
examination of vegetation abundance (Tables 1 and 2) in comparison to 
consumption (Tables 3-8) indicates that most abundant plant species were also 
important in the diet, and that rare plants were being used only in trace 
amounts. There were some interesting exceptions to this, however. Cheatgrass 
on Site 4 was dietarily important (39% relative density) but not recorded in the 
vegetation analysis. 

Diets became more diverse in May, probably as a result of grasses curing and 
seeds becoming available. Ground squirrels eat large amounts of seeds prior to 
entering torpor (pers. obs.). Perhaps if insufficient seeds are available 
during a drought year, TGS turn to insects as a fat source. However, at Site 2 
where insect use was highest in 1987, cheatgrass (mostly seeds) was the major 
constituent of the diet. This relationship should be explored further. 

Idaho and Columbian ground squirrels have highly varied diets of 11-25 
plant species per fecal pellet group (Dyni and Yensen, in prep. ) . However, in 
that study only 2-4 plant species (usually grasses) contributed >10% to the 
diet. Rogers and Gano (1980) found that only 3 plant species (Poa spp. , 
Descurainia pinnata , and Lupinus laxiflorus ) contributed >10% of the diet of TGS 
in southeastern Washington. Hansen and Ueckert (1970) found 1-5 species that 
contributed >10% in the diverse (47 plant species) diets of elegant ground 



119 



squirrels (S. elegans ) in Colorado. Hansen and Johnson (1976:750) concluded 
that "Richardson [=elegant] ground squirrels graze on a variety of plants as 
they fill their stomachs rather than selecting only preferred foods when their 
stomachs are nearly empty. This may be an evolutionary strategy developed to 
allow them to consume vetches. The dilution of toxic foods by non- toxic foods 
decreases the probability of plant poisoning . " 

The evolutionary strategy proposed by Hansen and Johnson (1976) may be 
general in members of the subgenus Spermophilus . To carry their thinking a step 
further, the strategy may be to specialize on 2-4 highly nutritional species but 
to supplement them with a wide variety of other species as "poisoning 
insurance." In this study, Townsend's ground squirrels similarly depended on 
only a few species for the bulk of the diet, but the wide variety of trace 
species was not available. The consequences of limited dietary variety on the 
long term nutrition of TGS are unknown. 

The question of whether TGS can adapt to exotic annuals as dietary staples 
is answered in the affirmative by this study. Native forb species were of minor 
importance in the diet, but this does not necessarily reflect preference. Native 
forbs were so rare at the 4 sites that none were recorded by the vegetation 
analysis (Tables 1 and 2), and thus apparently were not generally available for 
consumption. We are left with 2 interesting finer-scale questions. How well 
can exotic species supply TGS ' long-term energetic and nutritional needs? What 
would happen to TGS populations if a highly toxic plant species that could not 
be "diluted" in the stomach invaded the SRBOPA? 

An understanding of the timing of resource availability and consumption 
patterns should better uncover any resource limitations faced by Townsend's 
ground squirrels. Since 1987 and 1988 were drought years, future comparative 
work in non-drought years should help us understand how weather patterns and 
resource availability influence Townsend's ground squirrel diets. 



ACKNOWLEDGMENTS 

D. L. Quinney designed the sampling and provided collection information on 
the ground squirrel specimens and the vegetation analysis techniques. I thank 
J. Weaver and other Bureau of Land Management personnel who collected the 
squirrels and the vegetation data, B. Dyni and T. Foppe for discussion of the 
microhistological analysis technique, and I especially appreciate M. P. 
Luscher's assistance in preparing the slides. K. Steenhof and S. Knick made 
helpful comments on an earlier draft of the manuscript. 



LITERATURE CITED 

Alcorn, J. R. 1940. Life history notes on the Piute ground squirrel. J. 
Mammal. 21:160-170. 

Bray, J. R. , and J. T. Curtis. 1957. An ordination of the upland forest 
communities of southern Wisconsin. Ecol. Monogr. 27:325-349. 



120 



Cook, C. W. 1977. Effects of season and intensity of use on desert 

vegetation. Utah Agric. Exp. Sta. Bull. 483, Utah State Univ. 57pp. 

Daubenmire, R. F. 1959. A canopy-coverage method of vegetation analysis. 
Northwest Sci. 33:43-66. 

Davis, W. B. 1939a. The Townsend ground squirrels of Idaho. J. Mammal. 
20:182-190. 

Davis, W. B. 1939b. The recent mammals of Idaho. Caxton Printers, Ltd., 
Caldwell, ID. 400pp. 

Fitch, H. S. 1948. Ecology of the California ground squirrel on grazing 
lands. Am. Midi. Nat. 90:334-340. 

Fracker, S. B., and J. A. Brischle. 1944. Measuring the local distribution of 
Ribes. Ecology 25:283-303. 

Hansen, R. M. 1978. Shasta ground sloth food habits, Rampart Cave, Arizona. 
Paleobiology 4:302-319. 

Hansen, R. M. , and M. K. Johnson. 1976. Stomach contents weight and food 
selection by Richardson ground squirrels. J. Mammal. 57:749-751. 

Hansen, R. M. , and D. N. Ueckert. 1970. Dietary similarity of some primary 
consumers. Ecology 51:640-648. 

Holechek, J. L. , and B. Gross. 1982. Training needed for quantifying simulated 
diets from fragmented range plants. J. Range Manage. 35:644-647. 

Holechek, J. L. , and M. Vavra. 1981. The effect of slide and frequency 

observation numbers on the precision of microhistological analysis. J. 
Range Manage. 34:357-358. 

Holechek, J. L. , M. Vavra, and R. D. Pieper. 1982. Botanical composition 
determination of range herbivore diets: a review. J. Range Manage. 
35:309-315. 

Howell, A. H. 1938. Revision of the North American ground squirrels, with a 
classification of North American Sciuridae. North American Fauna 
56:1-256. 

Johnson, D. R. 1961. The food habits of rodents on rangelands of southern 
Idaho. Ecology 42:407-410. 

Johnson, D. R. , and G. W. Smith, R. M. Olson. 1977. Population ecology and 

habitat requirements of Townsend ground squirrels. Pages 203-224 in Snake 
River Birds of Prey Research Project, Annual Report, 1976. 

Johnson, D. R. , G. W. Smith, E. M. Cobb, and C. W. Woodley. 1978. Population 
ecology and habitat requirements of Townsend ground squirrels. Pages 
143-153 in Snake River Birds of Prey Research Project, Annual Report, 
1977. 



121 



Johnson, M. K. 1980. Food of Townsend ground squirrels on the Arid Land 
Ecology Reserve (Washington). Great Basin Nat. 37:128. 

Kochert, M. N. , and M. Pellant. 1986. Multiple use in the Snake River Birds 
of Prey Area. Rangelands 8:217-220. 

Leslie, D. M. , Jr., M. Vavra, E. E. Starkey, and R. C. Slater. 1983. 

Correcting for differential digestibility in microhistological analyses 
involving common coastal forages of the Pacific Northwest. J. Range 
Manage. 36:730-732. 

Ludwig, J. A., and J. F. Reynolds. 1988. Statistical ecology. John Wiley & 
Sons, NY. 

Costing, H. J. 1956. The study of plant communities, 2nd ed. W. W. Freeman, 
San Francisco. 

Rickart, E. A. 1982. The ecology of Townsend 's ground squirrei, Spermophilus 
townsendii mollis . Ph.D. Dissertation, University of Utah, Salt Lake 
City. 74pp. 

Rickart, E. A. 1982. Annual cycles of activity and body composition in 
Spermophilus townsendii mollis . Can. J. Zool. 60:3298-3306. 

Rogers, L. E. , and K. A. Gano. 1980. Townsend ground squirrel diets in the 
shrub-steppe of southcentral Washington. J. Range Manage. 33:463-465. 

Samuel, M. J., and G. S. Howard. 1983. Disappearing forbs in 

microhistological analysis of diets. J. Range Manage. 36:132-133. 

Smith, G. W., and D. R. Johnson. 1985. Demography of a Townsend ground 
squirrel population in southwestern Idaho. Ecology 66:171-178. 

Sparks, D. R. , and J. C. Malechek. 1968. Estimating percentage dry weight in 
diets using a microscopic technique. J. Range Manage. 21:264-265. 

U.S. Department of Interior. 1979. Snake River Birds of Prey. Special 
Research Report. U.S. Bur. of Land Manage., Boise Dist., Boise, ID. 
142pp. 

Vavra, M. , and J. L. Holechek. 1980. Factors influencing microhistological 
analysis of herbivore diets. J. Range Manage. 33:371-374. 

Yensen, D. L. 1980. A grazing history of southwestern Idaho with emphasis on 
the Snake River Birds of Prey Area. Prog. Rep., U.S. Dep. Inter., 
Bur. of Land Manage., Boise, ID. 82pp. 



122 



TITLE: Factors Affecting the Mating System in Townsend's Ground 
Squirrels . 

INVESTIGATOR: Claire Fuller, Dep. Zoology, Oregon State University 

COOPERATOR: Oregon State University 

INTRODUCTION 

This work was done as part of a pilot study to determine the effect of 
population density and sex ratio on reproductive success in Townsend's ground 
squirrel ( Spermophilus townsendii ) . Three study sites were established and 
animals were marked so that breeding activity could be observed the following 
winter . 

METHODS 

Three trapping grids for S_^ townsendii were established in the 
northwestern portion of the Snake River Birds of Prey Area (SRBOPA). Traps 
were set in winterfat communities in Sections 15, 20, and 21, Township 1 South, 
Range 1 West. Grids were 200 x 200 m per side (4 ha) with quadrat markers at 
20-m intervals. Animals on 1 of these grids {Grid 1) were trapped with 
Pymatung and/or National live- traps using apple pieces as bait. Because my 
primary objective was to trap and mark all resident squirrels, rather than 
determine population density, I set 2-4 traps per quadrat near burrow 
entrances. One quarter to one half of the grid was trapped at any one time 
(approx. 200 traps /day) . Traps were first set early in the morning (usually @ 
0730) then checked every 1.5-2 hours until approx. 1400. Animals were 
trapped on the grid from 4 May - 16 May 1989 and around the edges of the grid 
on 17 May 1989. 

At first capture, all animals were toe-clipped for permanent 
identification, sexed, weighed and the capture location was recorded. In 
addition, adults were anesthetized with ether and given an additional mark on 
their back with Clairol black hair-dye. This mark will facilitate 
identification of individuals from a distance. Pups were not dye-marked 
because the first 4 anesthetized stopped breathing and had to be resuscitated 
It is unclear why they were more susceptible to ether than adults. When 
animals were recaptured, they were identified and their location was recorded. 
Animals recaptured on 5, 9, 14 and 15 May were weighed again and these second 
weights were used to calculate growth rates. All animals were released at the 
point of capture. 

Animals were separated into adults and juveniles based on weight and, for 
females, on the presence or absence of enlarged teats or mammary glands. The 
largest male pup weighed 150 g and the smallest adult male weighed 208 g. For 
females, the largest pup weighed 137 g and the smallest adult weighed 142 g — 
these animals were exceptionally large and small, respectively. 



123 



RESULTS 

A total of 127 animals were captured in 11 days of trapping. Approximately 
200 traps were set per day. Twenty- three adults (8 males and 15 females) and 104 
juveniles (48 males and 51 females) were captured. Two pups were not sexed, and 
3 died in traps as a result of extremely hot or cold weather. 

Seventy-six of the animals were re-captured between 1 and 5 times (Fig. 1). 
Because only a small portion of the grid was trapped on any one day, this figure 
underestimates the trappability of Sj. townsendii . There were no differences in 
the number of times captured between age classes or sexes, suggesting that age 
and sex classes were equally trappable (Table 1). 

Adult males were significantly heavier than adult females (t = 5.74, df = 
21, P < 0.001; Table 1), and juvenile males were significantly heavier than 
juvenile females (+ = 5.09, df - 96, P < 0.001; Table 1). Growth rates were 
obtained for 16 juveniles which were re-weighed 2-11 days (mean = 6.3) after 
initial capture. One pup which lost weight was excluded from the analysis. Male 
pups grew significantly faster than female pups both in grams per day (t = 2.45, 
df = 14, P < 0.05; Table 1) and as a percentage of initial body weight per day (t 
= 2.13, df = 14, P < 0.05, Table 1). 



124 






CO 

_l 

< 



< 

O 
LU 




1 2 3 4 5 6 

NUMBER OF CAPTURES PER ANIMAL 



7 



Figure 1 , 



Frequency of Captures for Individual Animals. This represents data pooled across sex 
and age classes (see text). In addition, captures were pooled across a 2-week trapping 
period. Animals which were first marked later in the study were not "at risk" as long 
as animals marked early in the study Thus, these data can only be used to obtain a 
general idea of trappability. 



Table 1 . Comparison of mean capture rates and mean weights between sex and age 
classes of Townsend's ground squirrel. 



Adults 



Male 



Female 



Juveniles 



Male 



Female 



Number Caught 



15 



48 



51 



Number of Times 
Individuals were 
Captured (SD) 

Weight (SD)* 



Weight Gain in 
G/Day (SD)** 



2.67(1.37) 
n = 6 

248.9(24.9; 
n = 8 



2.67(1.32) 
n = 9 

186.4(24.7) 
n = 15 



2.66(1.55) 
n = 38 

115.5(12.2) 

n = 47 

2.38(1.16) 
n = 11 



2.42(1.19) 
n = 42 

104.3(9.5) 
n = 51 

1.03(0.60) 

n = 5 



Weight Gain in 
% Original Body 
Weight/Day (SD)** 



7.87(2.21) 
n = 11 



5.53(1.55) 
n = 5 



* Within age classes, males are significantly heavier than females; P < 0.001, 
Student's T-test. 

** Differences are significant at 0.05 level. Student's T-test. 



126 



TITLE: Parasites and Population Ecology in Kangaroo Rats. 

INVESTIGATOR: James C. Munger, Dep. of Biology, Boise State University 

COOPERATOR: Boise State University 
OBJECTIVES : 

1. To identify in a local population of kangaroo rats ( Dipodomys spp. ) a 
parasite species that is at reasonable prevalence and is relatively 
easy to work with. 

2. To establish a trapping grid to gather baseline data on the 
prevalence of selected parasite species and on the reproductive 
status of kangaroo rats. 

3. To perform preliminary studies to determine the effect of selected 
parasite species on the energy budget of host kangaroo rats. 

INTRODUCTION 

Little empirical evidence exists to allow a critical assessment of the 
role of parasitism in host population ecology. Over the last 4 years I have 
initiated studies that study the effects of parasites at two levels: (i) on the 
energy budget of host individuals and (ii) on the reproduction and survival of 
individuals. Effects at either level should have important ramifications for 
host populations. 

Research that I recently completed in Wisconsin documented effects of 2 
parasites, a tapeworm and a fly larva, on host white-footed mice. We showed 
that (i) both parasites have small but measurable effects on the host energy 
budget, (ii) we were unable to detect compensations for these perturbations in 
the energy budgets, leading us to conclude that effects on energy budget were 
not of major significance, (iii) we were unable to detect effects of either 
parasite on survival or reproduction (Munger and Karasov 1989 and in press, 
Munger et al . 1989 ) . 

The goal of the present research is to gather similar evidence on a 
different system. It is hoped that the methods I am using will eventually 
provide a means by which probable effects on host population dynamics can be 
predicted by study of parasites on selected components on the host energy 
budget . 

METHODS 

I trapped at several sites on the Snake River Plain before settling on the 
Rabbit Creek area north of Murphy in Owyhee County as the most desirable site 
for further study. It has substantial populations of kangaroo rats and there 
are sites which are relatively isolated from human activity. On 12 July 1989 a 
13 x 13 grid with 15 m between stations was established on the plain 
approximately 500 m W of Con Shea road, at T2S R2W S14. This has been trapped 
with Sherman live traps baited with millet on the occasions noted in Table 1. 



127 



Table 1. Number captured and prevalence (in parentheses) of Trichurus sp. 
infection. 



Date Dipodomys ordii Perognathus parvus Peromyscus maniculatus 

13 July 8 (12.5%) 1 (0) 

14 July 11 (27.3) 7 (0) 
2 August 36 (29.4) 22 (0) 

5 September 24 (20.8) 16 (0) 

6 October 8 (37.5) 8 (0) 3 (0) 



128 



All animals captured were identified to species and eartagged with monel 
fingerling tags. Reproductive status was assessed, and a fecal specimen was 
taken. Fecal specimens were analyzed for the presence of parasite eggs by 
standard centrifugal flotation techniques using saturated sucrose solution 
(Pritchard and Kruse 1982). 



RESULTS 

Table 1 depicts the captures by species and gives the prevalence of the 
only gut parasite ( Trichurus sp. , a nematode) both easily identifiable from its 
eggs and at reasonable prevalences. 

PLANS FOR 1990 

I plan to recommence trapping in March, and continue monthly trapping at 
least through July. In May, assuming prevalence of Trichurus is high enough, I 
will begin a laboratory study to assess the effect of this parasite on 
digestive efficiency of kangaroo rats. Thirty infected kangaroo rats will be 
brought into the laboratory, and digestive efficiency will be measured by the 
mass balance method (Munger and Karasov 1989). Then half the nematodes in half 
of the rats will be killed with Ivomectin, and digestive efficiency will be 
remeasured. If removal of the nematodes causes a significant increase in 
digestive efficiency, I will pursue other aspects of the effect of this 
parasite on the energy balance and population biology of kangaroo rats. 



LITERATURE CITED 

Munger, J. C. , and W. H. Karasov. 1989. Sublethal parasites and host energy 
budgets: tapeworm infection in white-footed mice. Ecology 70:904-921. 

Munger, J. C, and W. H. Karasov. (In Press). Sublethal parasites in 

white-footed mice: impact on survival and reproduction. Can. J. Zoology 

Munger, J. C, Karasov, W. H., and D. Chang. 1989. Host genetics as a cause 
of overdispersion of parasites among hosts: how general a phenomenon. J. of 
Parasitology 75:707-710. 

Pritchard, M. , and G. Kruse. 1982. The collection and preservation of animal 
parasites. University of Nebraska Press. 141pp. 



129 



TITLE: Effect of Wildfires on Soil Microbial Communities. 

INVESTIGATORS: Marcia Wicklow-Howard, Dep. of Biology, Boise State University 
Robert Rychert, Dep. of Biology, Boise State University 

COOPERATOR: Boise State University 

MICROBIAL ACTIVITY 

Study sites were established within the Snake River Birds of Prey Area 
(SRBOPA), Idaho. Sites were characterized as burned and unburned sagebrush, 
and as burned and unburned winterfat ( Ceratoides lanata) . The unburned 
sagebrush site is dominated by big sagebrush (Artemisia tridentata) and 
cheatgrass ( Bromus tectorum ) . Root and soil samples were taken from these 
sites immediately following the burns in August 1987 and then from April to 
June 1988. 

The sagebrush burn site exhibited reduced microbial activity and biomass-C 
(August 1987) when compared with the unburned site. The converse was true for 
the winterfat site. However, when dehydrogenase activity per unit biomass-C 
was compared for burned and unburned sites, the differences between activity 
and biomass on burned and unburned sites are not pronounced. By June 1988, the 
activity per unit biomass for the unburned sites is not significantly greater 
than the burned sites. In terms of overall microbial activity and biomass, 
spring rainfall readily lends to a restoration of any lost microbial activity 
and biomass following an intense summer rangeland fire. 

SOIL MINERAL NITROGEN 

The soil mineral nitrogen (N) status did exhibit pronounced differences on 
burned versus unburned plots on both the sagebrush and winterfat sites (Figs. 1 
and 2). While soils were analyzed for pH, organic-C, total phosphorous (P) , 
total N, and soluble P, only the NH4 + -N and NOr-N values were 
different on burned versus unburned plots. These preliminary results would 
suggest that the major impact of rangeland fires on soil microorganisms and 
their activities is reflected in major effects on the N cycle. Fire appears to 
enhance mineralization of N initially, and subsequently there is an increase in 
the soil N0 3 --N. The latter may be due to enhanced nitrification or 
reduced denitrification. Since biomass-C differences are not very great, the 
data suggest an enhancement of nitrification. 

MYCORRHIZAL ROOT INFECTION 

Roots of plant species were microscopically examined for the presence of 
mycorrhizal infection, and quantified to obtain percent root area infected 
(Table 1). In the unburned sagebrush site, it appears that big sage has a 
greater mycorrhizal infection at all samplings, as compared to cheatgrass and 
other grass species. Additionally, the mycorrhizal infection appears to 
increase from a low of 47% in April to a high of 80% in May. On the burned 
site, little root infection is noted for early spring on any of the plants 



130 



Sagebrush 



40 n 



30 



20 - 



NO^-N/g soil 



10 - 



burned 

unburned 




1 1 1 1 

Aug 87 Apr 88 May 88 Jun 88 



Fig. 1. Concentration of Soil Nitrate/Nitrogen following burn. 
(Mg/gr) 



131 



Winterfat 



30 n 



20 



NO3- N/g soil 



10 - 




- - - burned 

unburned 



1 1 1 1 r 

Aug 87 Apr 88 May 88 Jun 88 



Fig. 2. Concentration of Soil Nitrate/Nitrogen following burn, 
(/ig/gr) 



132 



mammma ^ stmmlll 



Table 1. Percent mycorrhizal root infection. Percent of samples indicated in parentheses. 



S tudy Site 



Sagebrush Sagebrush Winterfat Winterfat 
Plant Species Date Burned Unburned Burned Unburned 



Winterfat (Ceratoides lanata) APR 88 -- -- - (10) 0% 

MAY 88 -- -- -- (10) 0% 

JUN 88 -- -- -- (10) <o.i% 



SEP 88 (2) 0% - -- ( 9) 0* 



Big Sagebrush APR 88 -- (10) 47% 

(i r i e |i?ia tridentata MAY 88 -- (8) 80% 

var. wyoming ensis ) JUN 88 -- (8) 59% 

SEP 88 -- (4) 44% 



Cheat Grass (Brows tectoruj) MAY 88 -- ( 2) 34% 

JUN 88 ( 6) 1.5% ( 9) 21% 
SEP 88 ( 4) 7% ( 8) 8% ( 5) <0.1% ( 7) 0% 



Squirrel Tail (Sitanion hystrix) JUN 88 ( 2) 21% ( 1) 10% 

SEP 88 (1) <0.1% 



Unidentified Grass Species APR 88 ( 9) 4% (10) 16% ( 7) 0.1% (10) 0% 

MAY 88 (11) 14% ( 9) 29% ( 9) 3% (11) <0.1% 

JUN 88 -- -- ( 8) 0.4% (10) 0% 
SEP 88 



Russian Thistle (Salsola kali) MAY 88 ( 1) 0% 

JUN 88 ( 1) 0% - ( 5) 0% 
SEP 88 ( 3) 0% -- ( 4 0% 



Mustard (Descurainia p innate ) JUN 88 ( 1) 0% 



Prickly lettuce (Lactuca serriola) JUN 88 (1) 30% 



Onion (Allium sp.) APR 88 ( 1) 6% 



Burr Buttercup 

( Ranunculu s testiculatus) APR 88 -- ~ - ( i) o% 

Kochia SEP 88 -- - ( 2) 0% 

133 



initially colonizing the area. Generally, plants colonizing the sites the 
first year following a burn do not form mycorrhizal root infections. Species 
such as Russian thistle ( Salsola kali ) and cheatgrass appear to have little 
mycorrhizal dependence, and can colonize areas lacking mycorrhizal propagules. 
Changes in mycorrhizal spore numbers in soil were noted from April through June 
1988. On the winterfat site, spore numbers increase some during this period of 
time. Winterfat does not normally form mycorrhizae even when propagules are 
available. In contrast, the unburned sagebrush sites showed a decrease in 
spore numbers in the soil, as mycorrhizal root infections increased throughout 
the summer. 



134 



TITLE: Winterfat Seeding Projects in the Snake River Birds of Prey 
Area. 

INVESTIGATORS : Stephen B. Monsen, USDA-FS Shrub Sciences Laboratory 
Mike Pellant, BLM Idaho State Office 

C00PERATORS: USDA-FS Intermountain Research Station, Shrub Sciences Lab 

OBJECTIVE: Determine the establishment and recruitment of winterfat on 
reseeding projects. 

INTRODUCTION 

Revegetation plantings using winterfat ( Cera to ides l anata ) with various 
perennial grasses were established at 3 separate burn sites within the Birds of 
Prey area in the past 7 years. These sites include Melba, Kuna/Coyote, and 
Trio. Plantings were conducted using different methods of broadcast seeding on 
disturbed burns where winterfat and big sagebrush ( Artemisia tridentata ) had 
occurred. These plantings were the first attempts to seed winterfat with 
grasses on extensive areas of arid shrublands in southwestern Idaho. Different 
methods of broadcast seeding were used to revegetate the burns (Table 1). 
Methods of planting included hydroseeding , aerial seeding of pelleted and 
nonpelleted seed. The 3 large areas were seeded at different dates, and 
provide a useful number of sites to evaluate planting methods, initial 
establishment, survival, and natural spread of seeded shrubs. Studies were 
established in 1988 at the 3 planting locations to evaluate these factors. 
This report summarizes the results of shrub seedling recruitment that has 
occurred in 1988 and 1989. The previous year's progress report discussed the 
initial establishment attained by different seeding methods. To date, studies 
indicate that winterfat can be successfully established by different methods of 
broadcast seeding and that natural recruitment can occur rather rapidly even 
during years of low rainfall. However, the long-term results of these seedings 
have yet to be determined. 



METHODS 

Winterfat plants established at all 3 planting sites from the broadcast 
seedings conducted in the early 1980' s (Table 2). These plants matured and 
began to produce seed crops in 1987. New seedlings appeared in the spring of 
1988, and studies were initiated to record seedling establishment, survival, 
and the influence of associated plants and soil factors upon shrub seedling 
presence and growth. Permanent study plots established in 1988 were 
reinventoried in 1989 at all 3 planting sites. The number of plants that 
established in the spring of 1988 and 1989 were separately recorded. 

At the Melba location, study plots were separately established on sites 
that supported native stands of winterfat or Wyoming big sagebrush. Areas 
within the burn that were occupied by winterfat or sagebrush could be 
identified and separate study sites could be established. The occurrence of 
different plant communities at the Trio and Kuna/Coyote locations could not be 
determined following burning. 



135 



Table 1. Fire impacts and planting practices at 3 study sites in the Snake 
River Birds of Prey Area 



Melba 



Study Sites 
Kuna/Coyote 



Trio 



Date of Burn 
Date Seeded 
Ha Burned 

Planting Methods 



20 Aug 82 

March 83 

554 

Hydro/harrow 



19 Sept 81 

Nov 82 

10,664 

Aerial and 
hydro /harrow 



12 July 85 

March 86 

2,024 

Aerial pellet 
drill 



Table 2. Seeding success for 3 planting sites in the Snake River Birds of 
Prey Area. 



Melba Winterfat 
No . /ha 



Melba Sage 
No. /ha 



Kuna/Coyote 
No. /ha 



Trio 
No. /ha 



No. seeds sown 21,255 
No. plants attained 3,138 
% success 14.59 



21,255 

2,083 

9.80 



103,238 32,793 

2,194 944 

2.13 2.88 



136 



RESULTS AND DISCUSSION 

At all 3 planting locations, approximately 50% of all mature winterfat 
plants that established from broadcast seeding supported new seedlings in 

1988. By 1989, seedling numbers diminished, and about 30% of all mature shrubs 
at the Melba and Kuna/Coyote plantings supported seedlings (Table 3). Nearly 
all seedlings that appeared at the Trio site in 1988 failed to survive until 

1989. At the Melba location, 32% of the winterfat plants growing on the 
original winterfat sites were producing seedlings compared to 28% of the plants 
found growing on the original sagebrush communities. 

Winterfat seedlings were near or beneath the crown of a mature shrub. Few 
seedlings were further than 1-m from a mature plant. Winterfat seedlings often 
occurred in groups near the base of a mature plant (Table 3). Seedlings were 
usually spaced a few centimeters apart from each other. The winterfat 
seedlings encountered in 1989 were vigorous and well established individuals. 
Few seedlings would likely succumb, and most are expected to persist and 
develop into mature plants. 

Fewer plants became established at the Trio site from broadcast seeding 
than at either of the other 2 locations. In addition, fewer seedlings were 
encountered as natural recruitment. Mature plants at this location appeared to 
produce less seed than at the other sites. However, the lack of seedling 
survival cannot be explained from available data. 

Winterfat seedlings were able to establish amid considerable perennial 
herbaceous competition. Sandberg's bluegrass ( Poa secunda ) was the most 
abundant understory species at all locations. However, the presence of 
winterfat seedlings was not restricted by the density of this perennial grass 
even if grass cover exceeded 30% (Fig. 1). Perennial grass cover occurred in a 
rather normal distribution pattern at the Melba sage and Kuna/Coyote sites. At 
the Melba winterfat site, perennial grass cover increased following the burn, 
and a greater number of sites were occupied by Sandberg's bluegrass. A 
significant increase of Sandberg's bluegrass was recorded in all cover 
categories at this location. Yet, similar numbers of winterfat seedlings were 
recorded in sites where grass cover ranged from to 30% ( Fig . 1 ) . 

The recruitment of winterfat seedlings is occurring at a rapid rate, 
particularly for an arid shrubland situation. Although little or no 
recruitment was recorded prior to 1988, the seeded shrubs appeared to have 
reached maturity in 3 to 6 years and have produced seed crops in 1988 and 
1989. In addition, subsequent survival of new seedlings has occurred during 
periods of low rainfall. 

The presence of annual weeds, particularly cheatgrass ( Bromus tectorum ), 
did have a negative affect upon winterfat seedling survival. Most winterfat 
seedlings occurred on sites where the cheatgrass cover was lower than 10% (Fig. 
2). No other plant had such a strong negative influence upon shrub seedling 
survival. Although cheatgrass density adversely affected shrub seedling 
survival, this annual weed did not dominate all portions of the burns. 
Cheatgrass did not occur throughout the native winterfat communities prior to 
burning. In addition, annual grasses did not invade these areas very quickly 
after burning, particularly within sites where Sandberg's bluegrass was not 
killed by the fire. Study sites that supported Wyoming big sagebrush contained 



137 



Table 3. Number of seeded winterfat plants producing new seedlings in 1989, 



Planting Site 



Kuna Winterfat Kuna Sage Kuna/Coyote Trio 



% shrubs with 
seedling 



32 



28 



29 



% shrubs with 
multiple seedling 



21 



18 



138 



Melba Sage Site 

30 



m 
§ 

E 

t 

I 




Melba Winterfat Site 

20 

-2 



S3 
U 

a 
iS 



L^fJfi 



Cover Class 



Coyote Site 



30 






i 

H 
Ik 
•Ha 



I 



O 1 2 



.Eft- 



Fig. 1. Frequency of winterfat plants related to perennial grass 
cover. 



139 



Melba Sage Site 



30 



Q 

a 

a. 

£3 

t! 

g 

=*5 



Mi 



23430788 

Cover Class 



Melba Winterfat Site 



«3 
t 

Q 
I* 



i i i i i ■__ ._ 



2 3 4 B 8 

Cover Class 



ML 



7 8 » 



Coyote Site 



q 



a 

c 



1 



Z££i Za s«a tZa. e«i_ 



O 1 2 



3 4 S O 

Cover Class 



7 8 



Fig. 2. Frequency of winterfat plants related to annual grass 
cover. 



140 



a greater density of annual weeds than did the winterfat communities prior to 
burning. The annual weeds increased rapidly in these areas, but their presence 
did not restrict shrub establishment from the initial broadcast seedings or by 
natural recruitment. However, it is apparent that burned sites should be 
seeded before cheatgrass is able to establish or gain dominance. 

It is apparent that Sandberg's bluegrass controlled the invasion of 
annuals, but had less influence upon the recruitment of winterfat seedlings. 
This is an important ecological relationship, particularly as it affects 
restoration of native shrub communities. Burn sites are frequently seeded with 
an understory of introduced grasses as a means to control invasion of 
cheatgrass and other annual weeds. However, the presence of perennial grasses 
often restricts the recovery of native shrub and herb seedlings. If Sandberg's 
bluegrass could be used to selectively control annual weed invasion, yet allow 
for recruitment of desirable species, natural plant succession could be better 
employed to assure the recovery of diverse plant communities. 

The establishment of winterfat by broadcast seeding is encouraging. 
Numerous plants become established with minimal site preparation. In addition, 
natural spread has occurred very quickly even during years of below normal 
precipitation. Few shrub species are able to spread as well as winterfat, 
particularly into a competitive understory of herbaceous species. 

The winterfat seed that was planted on the 3 sites was acquired from a 
source in western Utah. It has a more upright growth from than the native 
ecotype, but it has grown well and has spread much better than the remaining 
natives. The long-term implications of seeding an introduced strain is not 
known. However, seeding winterfat on burn sites can be recommended, and 
plantings can be designed to allow for natural spread to increase stand 
density. Where possible, the presence of Sandberg's bluegrass should be 
maintained to control cheatgrass and act as a nurse crop to aid shrub seedling 
recruitment. 



141 



TITLE: 



INVESTIGATORS I 



COOPERATOR: 



OBJECTIVES: 



Environmental Monitoring in the Idaho Army National Guard 
Orchard Training Area. 

Dana Quinney, U.S. Army Corps of Engineers 
Marjorie Blew, Idaho Army National Guard 
Allison Brody, U.S. Army Corps of Engineers 
Robert Gerber, U.S. Army Corps of Engineers 
Jennifer Walrath, U.S. Army Corps of Engineers 
Jay Weaver, U.S. Army Corps of Engineers 
Jeff Courson, U.S. Army Corps of Engineers 
Wiliam Whitworth, U.S. Army Corps of Engineers 

U.S. Army Corps of Engineers CERL 
Idaho Army National Guard 

To assess and monitor the land condition and mammal populations 
in the Orchard Training Area in order to minimize the impacts 
of National Guard training. 



ANNUAL SUMMARY 

Two hundred ten permanent land condition-trend vegetation/soil monitoring 
plots were established and inventoried, and a program of monitoring small 
mammal populations was initiated. 

METHODS 

Vegetation/soils monitoring 

A May 1988 SPOT satellite image of the Orchard Training Area (OTA) was 
obtained, and the image was digitized using GRASS (Geographic Resources 
Analysis Support System) , a computerized geographic information system. Twenty 
land cover categories based upon reflectance values in the green, red, and 
near-infrared wavelength bands were determined. The resulting land cover data 
layer was superimposed on a digital soil series data layer derived from the 
maps in the Soil Surveys of Ada County Area (U.S. Soil Conservation Service, 
1960) and Elmore County Area (U.S. Soil Conservation Service, unpublished) Soil 
Surveys. Each unique land cover/soil series combination was recognized as a 
separate category. 

Using a computer algorithm, every occurrence of each unique land 
cover/soil combination was identified on a map of the Orchard Training Area as 
one or more polygons. Another computer algorithm determined the area of each 
polygon and eliminated all polygons smaller than 2 ha, leaving only those 
polygons large enough to locate and inventory in the field. Two hundred plots 
were to be established. Plot sites were chose by first determining the number 
of plots to be established in each land cover/soil type by assigning a number 
of plots proportional to the percent of land area occupied. For example, a 
land cover/soil series category comprising 10% of the total land area of the 
Orchard Training Area would be assigned 20 plot locations. The plot locations 
within each category were then allocated to the polygons of that category by 
random means. 



142 



The 200 plot locations were identified by map coordinates; these were the 
preselected sites of the land condition- trend analysis (LCTA) sampling plots. 
During field work, the locations of several LCTA plots were moved slightly 
(within the land cover/soil category) from their preselected map-coordinate 
locations in order to facilitate relocating them in later years, to minimize 
off-trail travel in reaching them, or to avoid entering the core artillery 
impact area. When establishing the plots in the field, no effort was made to 
avoid trails, tracks, berms or other disturbances. 

When a plot location was reached, a plot-midline azimuth was selected from 
a random number table, and a sighting compass was used to establish the plot 
midline on this azimuth. Each plot was given an identifying number. 

Each LCTA plot consisted of a belt 6 m wide and 100 m long, extending 3 m 
on either side of the plot midline. At every plot location, a midline was laid 
out using a 100-m tape. Each midline was permanently marked with steel 
stakes. At m on the midline, a 1.27-cm pipe (inside diameter) 46 cm long was 
driven into the ground, and a steel stake 63 mm in diameter and 46 cm long was 
dropped into it. At 25 m, 50 m, 75 m, and 100 m on the tape, another 46-cm 
steel stake was driven into the ground. 

Along the midline tape, a vegetation transect was sampled by dropping a 
1-m steel rod marked in decimeters, to the ground at 1-m intervals. The type 
of ground cover (or lack thereof) encountered by the pin at each drop-point 
(ordnance, gravel, rock, lichen, moss, grass litter, forb litter, shrub litter, 
dead wood, fecal material, plant species) was recorded; if the pin came to rest 
in a vehicle or mammal track or trail, or a mammal mound or burrow, this was 
recorded as well. At each sampling point, above-ground hits of litter, living 
plants, and dead wood on the steel rod were recorded, along with hit-height in 
decimeters. Litter was identified as grass, forb, or shrub litter. Living 
plants were identified to species and recorded by genus-species acronym. 

If one or more shrubs taller than . 1 decimeter were encountered on the 
plot, a belt transect was sampled. Shrubs were identified to species, and the 
location of each shrub in the belt was recorded (for example, 26 m, 1.2 m 
left), as well as its height in decimeters. Dead shrubs (snags) were recorded 
only if their height was equal to or greater than 1 m. However, the presence 
of shorter snags on a plot was noted. If the total number of shrubs of a 
species was fewer than 100 in the 6-m x 100-m belt, a 6-m wide belt was sampled 
for that species. If the total number of shrubs in a 6-m wide belt was greater 
than 100 but fewer than 200, a 4-m belt was sampled for that species, and if 
there were 200-400 shrubs per 6 x 100-m belt, a belt 2 m wide was sampled. If 
there were more than 400 shrubs of a species present in a 100 x 6-m belt, a 1-m 
belt was sampled for that species. Plots having different numbers of several 
species thus had several belt transects of different widths. Belt transects 
were always of equal width on each side of the 100-m midline. Belt width and 
shrub locations were measured using a collapsible, calibrated 6-m range pole, 
and shrub heights were measured using a steel rod calibrated in decimeters. 

Plant species not previously collected on the OTA, if encountered in the 
6-m x 100-m plot, were collected and pressed. Evidence of livestock grazing, 
troop bivouacing, vehicle tracking, fire, or other disturbance occurring on the 
plot was noted. 



143 



On each plot at 25 m and 75 m, 1 m to the right of the tape (facing the 
100-m rod) , 1-quart soil samples were collected. The soil samples were sent to 
the Soil Conservation Service National Soils Laboratory in Lincoln, Nebraska, 
for analysis. At m, 50 m, and 100 m on the plot midline, slope length and 
gradient were recorded using a measuring rod and a clinometer. Color 
photographs were taken of the view down the midline of each plot and of 
approaches to each plot, using a 35-mm camera. 

In addition, 10 LCTA plots were established as special-use plots, in order 
to monitor small-patch or unique habitats or high-disturbance areas. A more 
detailed explanation of the LCTA methods can be found in the U.S. Army Land 
Condition Trend Analysis (LCTA) Field Methods Manual (U.S. Army Corps of 
Engineers 1987). 



Small mammal and jackrabbit monitoring 

Sixty LCTA plots of the 200 were selected by unstratif ied random means for 
snap trapping mammals. Beginning in early July and ending on 1 September, 57 
of these plots were trapped for small mammals by William Whitworth and Jeff 
Courson of the U.S. Army Corps of Engineers Research Laboratory. Three of the 
60 preselected locations were not sampled because they fell inside the core 
artillery impact area. Three special-use plots, 91 (rocky drainage), 92 (rocky 
rim), and 113 (old sheep bedding ground in winter fat) were also sampled. 

On each mammal-trapping plot, 50 Museum Special (Woodstream Corporation, 
Lititz, Pennsylvania) snap traps baited with a peanut butter-oatmeal mixture 
were set at 2-m intervals in a straight line 5 m to the right (facing the 100-m 
rod) of the LCTA plot midline. Traps were set in late afternoon and checked 
the following morning. Each plot was trapped for 2 consecutive nights for a 
total of 100 trap-nights per plot. Species, sex, plot number, and date of 
capture were recorded for each animal caught. 

Abundance of black- tailed jackrabbits ( Lepus californicus ) in the OTA was 
monitored in 1989 using the method of Smith and Nydegger (1985). 



Townsend's ground squirrel and badger monitoring 

In June and July, 37 of the 57 mammal-trapping locations plus 3 
special -use plots (91, 92, and 113) were censused for Townsend's ground 
squirrel ( Spermophi lus townsendii , hereafter TGS) and badger (Taxidea taxus ) 
burrows. Year-active burrows of both Townsend's ground squirrels and badgers 
were distinguished from year-inactive burrows by the presence of one or more of 
the following: tracks, claw marks, freshly excavated earth, trails from the 
burrow entrance beaten through current-year vegetation, feces, exposed flexible 
rootlets in the burrow entrance, and observation of an animal using the burrow. 

TGS and badger burrow censusing was done by counting every year-active and 
year-inactive burrow in a belt plot 5 m x 400 m. Each censusing plot began at 
the LCTA-plot 0-m stake and continued along the plot midline for 100 m, then on 
in a straight line for an additional 300 mm. While sampling a plot, the pole 
technician carried a 5-m TGS censusing pole down a 400-m straight line. The 
TGS censusing pole has chains or rods hanging from each end; the pole can be 



144 



lowered, and these can be dragged along the ground to mark the boundary when 
there is a question of whether a burrow is inside or outside the belt 
boundary. One or more recording technicians followed the pole technician. The 
recorder (s) searched the belt for burrows as the pole carrier walked slowly 
along the line ahead, recording all TGS burrows and badger burrows and noting 
whether they were active or inactive. 



RESULTS 
Vegetation/soils monitoring 

In 1989, 210 LCTA plots were established and surveyed in the Orchard 
Training Area, 200 regular or "core" plots and 10 special -use plots. Sixty-six 
of these plots fell inside the boundary of the artillery impact area. No plots 
were established inside the boundary of the core artillery impact area. One 
hundred and eighteen of the 210 plots were located north of the BLM Sunnyside 
Winter/Sunnyside Spring-Fall grazing drift fence. LCTA plot data collected are 
on file in the office of the U.S. Army Corps of Engineers Research Laboratory, 
Champaign, Illinois, and at the Idaho Army National Guard Department of 
Engineering, Gowen Field, Boise, Idaho. Plant species collected or recorded in 
the OTA in 1989 are listed in Appendix 1; herbarium specimens have been 
archived in the herbarium of Colorado State University, Fort Collins, 
Colorado. Analysis of OTA soil samples by the U.S. Soil Conservation Service 
National Soils Laboratory is now underway. 

Small mammal and .jackrabbit monitoring 

The preliminary mammal survey resulted in the capture of the following 
species in the Orchard Training Area: Lepus californicus . Sylvilagus 
nuttallii, Eutamias minimus . Dipodomys ordii , Onychomys leucogaster , 
Perognathus parvus . Peromyscus maniculatus , and Neotoma cinerea . 
Mammal -capture data are on file in the office of the U.S. Army Corps of 
Engineers Research Laboratory, Champaign, Illinois, and at the Idaho Army 
National Guard Department of Engineering, Gowen Field, Boise, Idaho. 

Black-tailed jackrabbit censusing was done as part of the BLM Snake River 
Birds of Prey Area monitoring effort, and OTA results are included in the 
section of this annual report that reports jackrabbit abundance in the Snake 
River Birds of Prey Area. 

Townsend's ground squirrel and badger monitoring 

Forty burrow-count transects were sampled during June and July 1989 (Table 



145 



Table 1. 1989 Townsend's ground squirrel and badger burrow counts. 



Plot 


Active 


Inactive 


Active 


Inactive 


Comments 




TGS 


TGS 


Badger 


Badger 




5 


39 


8 


1 





IMPACT AREA 


32 


27 


19 


1 







33 


60 


10 


1 







50 





2 





1 




67 


36 


5 










75 


41 


? 


4 


1 




80 


24 


S 








IMPACT AREA 


81 


15 


8 








IMPACT AREA 


83 


21 


11 








IMPACT AREA 


85 


34 


8 


1 





IMPACT AREA 


86 


67 


13 


3 





IMPACT AREA 


87 


108 


2 


1 





IMPACT AREA 


88 


23 


1 


1 





IMPACT AREA 


89 


48 


5 








IMPACT AREA 


90 


60 


22 








IMPACT AREA 


91 


47 


23 








SPECIAL USE 


92 


14 


2 


1 


1 


SPECIAL USE 


93 


21 


12 








IMPACT AREA 


94 


25 


9 








IMPACT AREA 


95 


17 


8 


8 


8 


IMPACT AREA 


98 


13 


27 





8 


IMPACT AREA 


106 


21 


19 


1 


3 




108 


17 


9 


1 


1 


IMPACT AREA 


109 


4 


2 








IMPACT AREA 


111 


4 


4 





1 




112 


8 





1 


1 




113 


11 


3 


1 


1 


SPECIAL USE 


115 


33 


11 










116 


16 


13 


1 


1 




117 


78 


20 


11 


2 




118 


30 


19 


1 


3 




119 


56 


11 





8 




120 


34 


8 





1 




121 


42 


5 


3 


2 




122 


33 


2 










123 


27 


3 










124 


16 


2 










125 


48 


7 


1 


o 




130 


23 


7 


4 


1 


IMPACT AREA 


132 


49 


9 


1 








146 



LITERATURE CITED 

Smith, G.W. , and N.C. Nydegger. 1985. A spotlight, line- transect method for 
surveying jack rabbits. J. Wildl. Manage. 49:699-702. 

U.S. Army Corps of Engineers. 1987. U.S. Army land condition trend analysis 
(LCTA) Field Methods. 38pp. 

U.S. Soil Conservation Service. 1960. Soil Survey of Ada County Area, Idaho. 
U.S. Dep. of Agric, Soil Conserv. Serv. in cooperation with U.S. Dep. of 
the Inter., Bur. of Land Manage., Univ. of Idaho Coll. of Agric, Idaho 
Agric. Exp. Stn. ; Idaho Soil Conserv. Comm. 327pp. plus maps. 

U.S. Soil Conservation Service. Undated. Soil Survey of Elmore County Area, 
Idaho. U.S. Dep. of Agric, Soil Conserv. Serv. in cooperation with U.S. 
Dep. of the Inter., Bur. of Land Manage., Univ. of Idaho Coll. of Agric, 
Idaho Agric. Exp. Stn.; Idaho Soil Conserv. Comm. Unpublished manuscript 
and maps. 



147 



TITLE: Establishment of Monitoring Studies on Greenstrip Projects in 
the Snake River Birds of Prey Area. 

INVESTIGATOR: Mike Pellant, BLM Idaho State 

OBJECTIVES: 

1. Provide information to select drought affected greenstrips for 
reseeding . 

2. Quantify the effects of pretreatment vegetation, seedbed 
preparation/seeding techniques and year of treatment on initial 
establishment of greenstrip species. 

3. Establish baseline monitoring studies to evaluate .long term 
effects of grazing, climate and natural succession 

on persistence of seeded species and reestablishment of 
unwanted species. 

INTRODUCTION 

In 1984, Idaho BLM initiated a fire presuppression program, termed 
greenstripping to reduce the rate of spread of wildfires. Greenstripping 
involves establishing strips of fire-resistant vegetation at strategic 
locations to protect important resource values and reduce fire suppression and 
rehabilitation costs. Greenstripping is similar to past efforts to seed 
vegetative fuel breaks; however an intensive research and technology transfer 
effort has been added to the current program. 

Greenstripping has been employed within the Snake River Birds of Area 
(SRBOPA) to protect shrub stands from wildfires and to reduce fire frequency, 
thereby accelerating shrub recruitment in previously burned areas (Kuna Normal 
Fire Rehabilitation and Greenstripping Plan 1987). 

A thorough monitoring and evaluation program is being implemented to 
monitor progress in meeting the program objectives. Inspections of greenstrip 
projects are conducted throughout each growing season to record "greenness" and 
vigor of seeded species. 

Pace frequency transects were established on 4 greenstrip projects within 
the SRBOPA in 1987. Selected study sites were resampled in 1988; all studies 
were reread in 1989. Study locations and data are on file in the Boise 
District's Bruneau Resource Area and with the author. 

Intensive monitoring studies were established on 2 greenstrip projects in 
1988 (Monsen and Pellant 1988) . Density, frequency and cover measurements were 
recorded on 5 replicated transects at each study site. 

The studies described in this report were established on 8 greenstrip 
projects in the SRBOPA (Table 1). Field work was accomplished by the Boise 
District's monitoring crew during the summer of 1989. 



148 



Table 1. Study 


site locations 


, year greenstri 


p establ 


ished, 


and site 




preparation/seeding techniques 


used 


to establish selected SRBOPA 


L 


greenstrip projects. 


















Project 




Legal Locatior 


[i 




Site Pn 


& Seed Tec 


Name 


Year 


T. 


R. 


SEC 


1/4 


Veg.2 


Burn 


Disk 


Drill 


D-chn 


Milepost 96 


1984 


4S 


3E 


04 


NW 


BRTE 


X 




X 




Bennett/Interst . : 


1984 




















Site 1 




4S 


7E 


09 


SE 


ARTR 


X 




X 




Site 2 




4S 


7E 


15 


SE 


BRTE 


X 




X 




RRMP: 


1986 




















Site 1 




5S 


8E 


06 


NW 


BRTE 


X 


X 


X 




Site 2 




5S 


8E 


17 


NW 


BRTE 


X 


X 


X 




Site 3 




5S 


7E 


13 


SE 


BRTE 


X 


X 


X 




Dorsey: 


1986 




















Site 1 




4S 


5E 


18 


NW 


BRTE 




X 


X 




Site 2 




4S 


4E 


13 


SE 


BRTE 


X 


X 


X 




Site 3 




4S 


4E 


24 


NW 


ARTR 




X 


X 




Site 4 




4S 


4E 


23 


SW 


ATCO 




X 


X 




Site 5 




4S 


4E 


22 


SE 


ATCO 


X 


X 


X 




Site 6 




4S 


4E 


28 


NW 


ATCO 


X 


X 


XA« 




Site 7 




4S 


3E 


13 


SW 


BRTE 




X 


XA 




Site 8 




4S 


3E 


13 


SW 


BRTE 


X 


X 


XA 




Sites 9-11 




4S 


4E 


17 


SW 


BRTE 


X 


X 


XA 




Site 12 




4S 


4E 


15 


SW 


ATCO 


X 




X 




Milepost 101: 
Site 1 


1987 






















4S 


7E 


23 


SW 


BRTE 


X 






X 


Site 2 




4S 


7E 


25 


SW 


BRTE 


X 






X 


Cinder Cone: 


1987 




















Site 1 




3S 


4E 


03 


NE 


ARTR 








X 


Site 2 




3S 


4E 


10 


NE 


ARTR 








X 


Site 3 




3S 


4E 


10 


SE 


ARTR 


X 






X 


Crater II: 


1987 




















Site 1 




2S 


5E 


34 


NE 


BRTE 


X 






X 


Site 2 




2S 


5E 


27 


SW 


BRTE 








X 


Site 3 




2S 


5E 


33 


NE 


BRTE 


X 






X 


White Sage: 


1987 




















Site 1 




IN 


1W 


28 


NE 


ARTR 








X 


Site 2 




IN 


1W 


28 


NE 


ARTR 


X 






X 


Initial Point: 


1988 




















Site 1 




IN 


1W 


25 


SE 


ARTR 


X 




X 




Site 2 




IN 


1W 


25 


SW 


ARTR 


X 






X 


Site 3 




IN 


1W 


36 


NE 


BRTE 








X 



Legal Location 1 - Study site locations are presented as T. (Township), R. 
(Range), Sec. (Section), and 1/4 (quarter section study site is in). 

Veg. 2 - Indicates dominant vegetation occurring on the study site immediately 
preceding greenstrip implementation. 

Site Prep, and Seed Tech. 3 - Provides information on whether site was burned 
during the year that greenstripping was done and the type of mechanical 
equipment used to complete seedbed preparation and/or seeding. "D-chn" 
indicates that a disk chain was used to prepare the seedbed and to distribute 
seed. 

XA 4 - "A" indicates that a cultipacker was used to firm the seedbed prior to 
drill seeding. 



149 



METHODS 

The "Freqdens" (acronym for frequency-density) technique was developed 
specifically for measuring initial establishment and persistence of seeded 
species on Idaho greenstrip projects. This technique is relatively quick 
and inexpensive thereby stretching limited funds available for greenstrip 
monitoring. Replicated transects are permanently located to facilitate 
statistical analysis. 

Study site locations are selected by resource specialists on 
representative portions of selected greenstrips. A reference post is 
installed, and a 30-m (100-foot) baseline is established. Five belt 
transects are randomly established within 6-m (20-foot) divisions 
perpendicular to the baseline. Ten 50 x 50-cm plots are read at 1.5-m 
(5-foot) intervals (5, 10, 15... 50 feet) on each belt transect. 

Three sampling techniques are utilized to collect data on each belt 
transect: 

No. of samples Total No. of samples 
Sampling technique per belt transect per study site 

Nested frequency 10 50 

Density 10 50 

Point Cover 40 200 

Density and nested frequency data are recorded for all seeded species 
(seedling and mature plants are recorded separately). Dominant annual 
species are recorded separately; less common annual species are combined 
as "annual grasses" or "annual forbs". 

Point cover data are recorded from 4 points on the sampling frame 
within the categories of bare ground, litter, vegetation and rock. One 
1/100 acre plot is also established at each point where the belt transect 
crosses the baseline. All seedling and mature shrubs occurring in the 
plot are counted and recorded separately. 

The final study component is a "Vegetation Condition Worksheet" which 
documents (qualitatively) vigor, height, utilization, phenology and 
relative greenness of all seeded and dominant annual and perennial 
species. Two general view and one close-up photograph are also taken at 
each study site. 



RESULTS 

All data collected during the 1989 field season have been summarized 
and are available for inspection at Boise District or with the author. 
Data are currently being analyzed at the Range Sciences Department of the 



150 



University of Idaho. Findings from this analysis will be incorporated 
into a presentation for the 1990 Society for Range Management Annual 
Meeting in Reno, Nevada (February 1990). 

A BLM progress report on findings from greenstripping research and 
evaluations, including these studies, will be prepared in 1990. This 
report will focus on the desirability of burned versus unburned seedbeds, 
effectiveness of three types of equipment treatments (rangeland drill, 
disk and rangeland drill and disk chain) , year of treatment and 
pretreatment vegetation community (Table 1). 



ACKNOWLEDGMENTS 

I thank Jack LaRocco and the Boise District Monitoring Crew for their 
assistance in fine tuning the study procedures and completing the field 
work. They toiled under harsh environmental conditions and efficiently 
and accurately completed these studies. 



LITERATURE CITED 

Monsen, S., and M. Pellant. 1988. An evaluation of selected 

greenstripping and winterfat seeding projects in the Snake River 
Birds of Prey Area. Pages 141-150 in K. Steenhof , ed. Snake River 
Birds of Prey Research Proj. Annu. Rep., Bur. Land Manage. Boise, 
Idaho. 

U. S. Department of the Interior. 1987. Kuna normal fire rehabilitation 
and greenstripping plan. Bureau of Land Manage. Boise Dist., Idaho. 
71pp. 



I'KiN'l'lNU OPl'MCili I yy<) ■ --'/y J -789/23047 

151 




BLM LIBRARY 
SC-653, BLDG. 50 
DENVER FEDERAL CENTER 
p. 0. BOX 25047 
DENVER, CO 80225-0047 



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