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ANIMAL COMMUNITIES IN TEMPERATE 
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THE UNIVERSITY OF CHICAGO PRESS 
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THE CAMBRIDGE UNIVERSITY PRESS. 

LONDON AND EDINBURGH 

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THE GEOGRAPHIC SOCIETY OF CHICAGO 
Bulletin No. 5 



ANIMAL COMMUNITIES IN 
TEMPERATE AMERICA 

AS ILLUSTRATED IN THE 
CHICAGO REGION 

A STUDY IN ANIMAL ECOLOGY 

BY 

VICTOR E. SHELFORD, Ph.D. 

of the Department of Zoology 
The Uni-versity of Chicago 




PUBLISHED FOR THE GEOGRAPHIC SOCIETY OF CHICAGO 

BY 

THE UNIVERSITY OF CHICAGO PRESS 
CHICAGO, ILLINOIS 



Copyright IQ13 By 
The Geographic Society of Chicago 



All Rights Reserved 



Published October IQ13 



Composed and Printed By 

The University of Chicago Press 

Chicago, Illinois, U.S.A. 



PREFACE 

Courses in field zoology usually lack the convenient background of 
organization which one finds in the doctrine of evolution when presenting 
the animal series from a structural standpoint. The need of some 
logical and philosophical background for the organization of natural 
history instruction into something more unified than haphazard dis- 
cussions of such animals as were encountered in chance localities, was 
keenly felt at the beginning of the author's experience as a teacher of 
field zoology. Evolutionary background was tried, but failed and was 
rejected; genetics and faunistics proved inadequate. Behavior as 
presented and studied by zoologists was incomplete. Plant ecological 
methods were, when unadapted, applicable only in part, while much 
of physiology dealt with organs and internal processes. 

The organization of the data here presented is the result of many 
attempts and failures which at times made the task seem hopeless. The 
literature relating to this subject has been written almost exclusively 
from points of view which are v^y different from the one here presented. 
It is scattered, and the bibliography has never been brought together. 
Accordingly its incorporation here has called for the expenditure of 
much time, and often for reinterpretation, which is always fraught with 
danger of error. The time consumed in working over the literature has 
been great, but, for the reason stated, the amount covered has been rela- 
tively small, and the literature in foreign languages has not received its 
share of attention. Furthermore, since the bulletin is not written 
primarily for investigators, much of the literature not in English has 
been omitted from the Bibliography but some of it will be found in the 
papers cited. To present such a subject as we have before us without 
constant reference to the writings of such naturalists as Buffon, White, 
Darwin, Wallace, Bates, Belt, Hudson, Romanes, Audubon, Brehm, 
Fabre, Claude Bernard, Huber, Giard, Forel, Schmarda, Janet, Haase, 
Mobius, Dahl, and others (35a) seems at first thought quite unjustified, 
but a complete study of the works of such men would be almost a life's 
work in itself. The writer does not claim to have a detailed knowledge 
of all the articles written by these men. He knows them only in part. 
Their facts, in so far as they are known to him and relate to the questions 
at hand, tend to support the main contentions. But the successful 
organization of such a subject depends more upon the investigation of 



vi ANIMAL COMMUNITIES 

the particular species and localities covered than upon work done from 
different points of view in remote localities. This bulletin is not intended 
as a textbook. Several years of work would be necessary to give it the 
completeness and form which a textbook should have, and the physiology 
which should be included in such a textbook is almost entirely omitted. 

The organization here presented has in the main grown out of three 
lines of thought: (a) the physiology of organisms as opposed to the 
physiology of organs (51)'; (b) the phenomena of behavior and physi- 
ology, as illustrated by the studies of Loeb (72), much of the data of 
which can be related to natural environments; and (c) the organized 
comparable data of plant ecology, as set forth by Cowles (58) and 
Warming (12). The results of these five years of labor will not be 
pleasing to many zoologists because the principles of evolution, heredity, 
etc., have not been correlated. Their omission, however, has not been 
due to any prejudice against their introduction, but rather to the fact 
that they can only occasionally be related to this line of organization. 
It was thought also that the complexity of the problems and concepts 
here treated made separation a necessity to clearness. 

The number of problems thrown open by the investigation is infinite. 
Naturalistic observation and survey work could be carried much farther 
along the lines here blocked out. The chief lesson which the author has 
drawn from his labors is that experimental study, conducted with due 
reference to the relations of the animals to natural environments, with 
conditions carefully controlled, and a single factor varied at a time, is 
one of the stepping-stones to future progress. We are confronted with 
centuries of animal and human geography, with only inference or specu- 
lation as to controlling factors for a background, and the experimental 
study of factors in the case of man and other land animals only at its 
beginnings. Though man is a land inhabitant, all. the best work along 
these and many other lines has been done upon aquatic animals. The 
writer's course in the future will probably be determined by the needs 
of the science, and \Yill be turned from the purely naturalistic method 
of study to a method made up of naturalistic observations and con- 
trolled experiments. 

In undertaking a new line of work, one must have first, inspiration, 
next, method and motive, and finally, in the case of ecological work, the 
assistance of a large number of persons in various departments of 
knowledge. For such assistance I wish to express my indebtedness to 

' Numbers in parentheses, scattered through this woric, refer to references in the 
Bibliography at the end (pp. 325-36). 



PREFACE vii 

the following: to Professor C. M. Child, of the University of Chicago, 
for my first serious inspiration in natural history, and for my oppor- 
tunity to develop ecology; he has also rendered important assistance 
in connection with the preparation of this work, by giving information 
regarding animals about Chicago; his assistance with the worms and 
other lower invertebrates has been of particular importance; to Dr. H. C. 
Cowles, of the University of Chicago, for constant assistance with the 
plants and all matters relating to plant ecology. Various graduate 
students and assistants at the University of Chicago have also aided 
materially in the preservation of notes, specimens, and records. Mr. 
Beniah H. Dimmot, Dr. W. C. AUee, Mr. G. D. Allen, Mr. S. S. Visher, 
and Mr. M. M. Wells should be mentioned especially. Mabel Brown 
Shelford collected the data on the former occurrence of animals now 
extinct, and on other historical matters. 

The following have furnished identifications and important advice 
in connection with the various groups in which they are specialists: 

Dr. N. A. Harvey, Ypsilanti, Mich., Sponges. 

Dr. R. C. Osburn, Columbia University, Polyzoa. 

Dr. J. P. Moore, University of Pennsylvania, Leeches. 

Mr. F. C. Baker, Chicago Academy of Sciences, MoUusca. 

Dr. C. D. Marsh, U.S. Department of Agriculture, Copepods. 

Mr. Richard W. Sharpe, Brooklyn Institute, Ostracoda. 

Dr. Chauncey Juday, University of Wisconsin, Cladocera. 

Dr. E. A. Ortmann, Carnegie Museum, Crayfishes. 

Miss A. L. Weckel, Oak Park, 111., Amphipods. 

Miss Harriet Richardson, U.S. National Museum, Isopods. 

Mr. O. F. Cook, U.S. Department of Agriculture, Myriopods. 

Dr. R. H. Wolcott, University of Nebraska, Water Mites. 

Mr. Nathan Banks, U.S. Department of Agriculture, Spiders. 

Mr. C. A. Hart, University of Illinois. All groups of insects. 

Dr. J. G. Needham, Cornell University, Aquatic insects. 

Dr. Cornelius Betten, Lake Forest University, Caddis-flies. 

Mr. W. J. Gerhard, Field Museum, Hemiptera and general entomology. 

Mr. A. B. Wolcott, Field Museum, Beetles. 

Prof. H. F. Wickham, University of Iowa, Beetles. 

Pr. Joseph Hancock, Chicago, Orthoptera. 

Mr. W. S. Blatchley, Indianapolis, Orthoptera. 

Dr. A. D. MacGillivray, University of Illinois, Sawflies and insect larvae. 

Dr. S. E. Meek and Mr. S. F. Hildebrand, Field Museum, Vertebrates. 

Mr. Alexander Kwiat, Chicago, Lepidoptera. 

Miss Clara Cunningham, South Bend, Tamarack Swamps. 

Dr. Frank Smith, University of Illinois, Annelids. 



Vlil ANIMAL COMMUNITIES 

Mr. S. S. Visher and Mr. Ralph Chaney contributed most of the habitat data 
on birds. Dr. R. M. Strong verified those included here which were 
also compared with Butler's account (io8). T. C. Stephens supplied the 
photographs of nests. 

Dr. P. G. Heinemann, University of Chicago, Bacteria. 

Dr. Susan P. Nichols, Oberlin College, Algae. 

Mrs. Elva Class and Mr. M. M. Wells of the University of Chicago, and Dr. 
W. C. AUee, of the University of Illinois, Gas analysis. 

Mariner and Hoskins, Commercial Chemists, Analysis of Water. 

The original records upon which the work is largely based could not 
all be presented. Those placed at the end of the chapters are believed 
to be representative, in that they include some characteristic animals, 
some which are numerous but occur elsewhere also, and some of wide dis- 
tribution. The records in the text are also largely original, except in the 
case of mammals, the habitat locations of which are based upon literature. 
Mr. W. H. Osgood of the Field Museum has assisted in the editing of the 
data on mammals. Original records in this group are especially indicated. 
Data on the nesting habits of birds have likewise depended upon compila- 
tion, though the locality records are those of the persons mentioned. 
Mr. W. S. Stahl, assistant United States attorney, edited the paragraphs 
on the legal restrictions upon field study and collection of animals. 

The matter of scientific names is one presenting unusual difiiculties 
because of the scattered and incomplete character of catalogues. The 
work of identification having occupied several years^ changes in nomen- 
clature may have led to some confusion and duplication of records under 
different names. The matter of correcting spelling is unusually difficult 
because of numerous works which it is necessary to consult for verification 
in dealing with representatives of nearly all groups from Protozoa to 
mammals. The specialists on the different groups have been very kind 
in answering any question, but the final responsibility rests with the 
author. In the main the nomenclature in the following works has 
been followed (numbers refer to Bibliography at the end of this work) : 
mammals, 21; birds, 108; reptiles, 157, 157a; Amphibia, 139 and 152; 
fishes, 79; flies, Aldrich's ('00) Catalogue (N.A.); beetles, 156 and 
Samuel Henshaw's ('85) checklist; Hemiptera {Keteroptera) , Bank's ('11) 
Catalogue; aquatic insects, 95 and 96; ants, 54; insects not included 
in the special lists, 177; Hymenoptera not in 177, E. T. Cresson's ('87) 
Synopsis; spiders, 159; Pkalangidae a.ndla,ndmites, 1^2 and 184; water- 
mites, 149; myriopods, 183; moUusks, F. C. Baker's ('06) Catalogue 
for Illinois; leeches, 91a; crayfishes, loi, loia; amphipods, 102; isopods, 



PREFACE ix 

182; copepods, 146, 146a; ostracods, 147; other Entomostraca, Herrick 
and Turner's ('95) synopsis for Minnesota. 

In the case of several names not included in any of these works there 
are contradictory spellings, authors, etc., and we have used some name 
which we believe will be understood. 

In bringing together the illustrations, material assistance has been 
rendered as follows: 

Dr. S. W. Williston, loan of Figs. 30, 31, 32, 126, 132, 174, 186, 187, 188, 210, 
267, 269, 270, 271, 272, 273, 274, 275, 282, 283, 284, 285, 286, from his 
Manual of North American Diptera. 

Dr. F. R. Lillie and the Biological Bulletin, loan of Figs. 66, 67, 68, 69, 83, 84, 
85, loi, 251, 252, 253, previously published by the author in the Biological 
Bulletin. 

Professor S. A. Forbes, the Illinois State Laboratory, and the State Ento- 
mologist's Ofl&ce, loan of Figs. 35, 36, 44, 45, 46, and 72, which appeared in 
Vol. Ill of the Natural History Survey of Illinois, and for electrotypes of 
Figs. 261, 262, 264, 265, 288, 289, 290, 291, 292, 296, 297, 301, 302, 303, 304, 
305, 306, which appeared originally in the Annual Reports and Bulletins 
of the State Entomologist and other state and national publications. 

Professor S. E. Meek and the Field Museum, loan of Fig. 37. 

Professor J. M. Coulter and the Botanical Gazette, loan of Fig, 115. 

Professor F. L. Washburn and the Minnesota State Entomologist's Office for 
electrotypes of Figs. 136, 137, 156, 189, 194, 211, 212, 213, 229, 256, 263, 
266, 268, 276, 277, 278, 293, 298, 299, 300. 

Professor Vernon L. Kellogg, privilege of using Figs. 188, 270, 271, 274 from 
North American Insects, which appear also in Williston's Manual of 
North American Diptera. 

Professor J. H. Emerton, privilege of using Figs. 207, 208, 224; 225 from Com- 
mon Spiders. 

Figures after Lugger appeared originally in Bulletins 35, 66, and 6g and the 
Fourth Annual Report of the Minnesota Agricultural Experiment Station. 

Figures after Marlatt, Riley, and Chittenden appeared originally in publica- 
tions of the U.S. Department of Agriculture; after Gorham, Smith, 
Jennings, and Reighard, in publications of the U.S. Fish Commission. 

The author is also indebted to Dr. J. P. Goode, Dr. Otis W. Caldwell, 
Dr. H. C. Cowles, Professor R. D. SaHsbury, Professor C. M. Child, 
and Mr. M. M. Wells for assistance in editing the manuscript and read- 
ing proof. Mr. W. J. Gerhard rendered special assistance in the reading 
of the proof of the scientific names. 

It is evident from the number of persons who have assisted in the 
working over of material and the accumulation of the data on which this 



X ANIMAL COMMUNITIES 

work is based, that the survey aspect of ecology is a subject for co- 
operative investigation. Because of the complexity of the problems, it 
has been deemed advisable to publish this work even in its present 
preliminary and necessarily incomplete form, in order to make the 
material accessible as soon as possible to teachers, investigators, and 
others who are interested. 

Department of Zoology : 

University of Chicago 
September 9, 1912 



TABLE OF CONTENTS 



PAGE 



Introduction . i 

CHAPTER 

I. Man and Animals . s 

I. Introduction . 5 

II. The Struggle in Nature 6 

III. Man's Relation to Nature 8 

IV. The Economic Importance of Animals 20 

II. The Animal Organism and Its Environmental Relations 22 

1. Nature of Living Substance 22 

II. The Relation of Form or Structure to Fimction .... 22 

III. The Basis for the Organization of Ecology 23 

IV. Scope and Meaning of Ecology 32 

V. Communities and Biota ' . . 33 

III. The Animal Environment: Its General Nature and Its 
Character in the Area of Study 42 

I. Nature and Classification of Environments 42 

II. The Important Factors and Their Control in Nature -43 

III. History of the Region about Lake Michigan .... 44 

IV. Extent and Topography of the Area Considered ... 48 
V. Climate and Vegetation of the Area 49 

VI. Localities of Study (Guide) 50 

VII. Legal Aspects of Field-Study 56 

IV. Conditions of Existence of Aquatic Animals .... 58 

1. Introduction: Comparison of Land and Aquatic Animals 58 

II. Chemical Conditions 58 

III. Physical Conditions 60 

IV. Elementary Food Substances 65 

V. Quantity of Life in Water 67 

V. Animal Communities of Large Lakes (Lake Michigan) 73 

I. Conditions 73 

II. Communities of the Lake 73 

III. Summary 81 

VI. Animal Communities of Streams 86 

J. Introduction . 86 

II. Communities of Streams 86 

III. Special Stream Problems 105 

xi 



XU ANIMAL COMMUNITIES 

CHAPTER PAGE 

VII. Animal Communities of Small Lakes 124 

I. Introduction 124 

II. Communities of Small Lakes 125 

III. Succession in Lakes 133 

VIII. Animal Communities of Ponds 136 

I, Introduction 136 

II. Area of Special Study 136 

III. Communities of Ponds 140 

IV. Succession 151 

IX. Conditions of Existence of Land Animals 157 

I. Introduction 157 

II. Soil 157 

III. Atmosphere 159 

IV. Combinations or Complexes of Factors 161 

V. Quantity of Life on Land 166 

X. Animal Communities of the Tension Lines between Land 

and Water 169 

I. Introduction 169 

II. Communities 169 

III. General Discussion 183 

XL Animal Communities of Swamp and Flood-Plain Forests 189 

I. Introduction 189 

II. Swamp Forest Formations and Associations 189 

XII. Animal Communities of Dry and Mesophytic Forests 209 

I. Introduction 209 

II. Forest Communities on Clay 209 

III. Forest Communities on Rock 217 

IV. Forest Communities on Sand 218 

V. Mesophytic Forest Formation 233 

VI. General Discussion 247 

XIII. Animal Communities of Thickets and Forest Margins . 262 

I. Introduction 262 

II. Low Forest Margin Sub-Formations 262 

III. High Forest Margin Sub-Formations 268 

IV. General Discussion 274 

XIV. Prairie Animal Communities .......... 278 

I. Introduction 278 

II. Prairie Formations 278 

III. General Discussion 295 



CONTENTS Xlil 

CHAPTER PAGE 

XV. General Discussion ' .... 299 

I. Introduction 299 

II. Application of the Laws Governing Animal Activities to 

World and Regional Problems 299 

III. Agreement between Plants and Animals 304 

IV. Relations of Communities 308 

V. General Relation of Communities of the Same Climate . 311 

VI. Relations of Ecology to Other Biological Subjects . 315 

VII. Relations of Ecology to Geography 318 

Appendix: Methods of Study 321 

Bibliography 325 

Index of Authors and Collaborators 339 

Index of Subjects 343 



INTRODUCTION 

Just at the beginning of the present century, there seems to have 
been a revival of interest in plants and animals in relation to their 
environments, and various workers have turned from the study of 
anatomy and classification in the laboratory to the study of organisms in 
nature. In this, the botanists have preceded the zoologists, in success 
if not in time. In 1901 Dr. H. C. Cowles published a bulletin on the 
Plant Societies of the Chicago Area. This was one of the first attempts of 
an American biologist to treat all the plants of a given area in a strictly 
ecological manner. This study of all the organisms of an area, from the 
point of view of their relations to each other and to their environment, 
is still a new or at least a renewed idea. Zoologists have devoted most 
of their attention to the study of animals from the standpoint of a single 
individual and of single species. Practically all of the more general 
study has been comparative. We have comparative anatomy, compara- 
tive embryology, comparative physiology, and comparative psychology. 
These are comparisons of the structure or physiology of one species, or 
group of species, with that of another species or group of species. 

Our point of view is very different. We shall deal with many species 
from the standpoint of their dependence upon each other and their 
relations to their environments. We shall attempt to present what has 
been learned upon this subject during several years of investigation and 
field teaching. In the spring of 1903, the writer made his first field 
excursion in the Chicago area, and from that time has been engaged in 
further study of the subject. 

The study of organisms in relation to environment is entitled ecology. 
The definition of ecology, like that of any growing science, is a thing to 
be modified as the science itself is modified, crystallized, and limited. At 
present, ecology is that branch of general physiology which deals with the 
organism as a whole, with its general life processes, as distinguished from 
the more special physiology of organs (51), and which also considers the 
organism with particular reference to its usual environment. 

Undertaking such a study from the point of view of many organisms 
involves matters of both ecological and taxonomic classification. Classi- 
fication of animals is difficult because animals are so exceedingly numer- 
ous. There are probably from 10,000 to 20,000 species of animals which 
the naturalist may encounter in the area which we are treating, while 

z 



2 ANIMAL COMMUNITIES 

in the same area the botanist would probably find only about 2,000 
conspicuous plant species. Representatives of all animal species must 
be submitted to specialists for identification, ^hat is, the specialist 
gives the correct scientific name to the animal. Scientific names are 
definitely arranged as below, if man is taken as an example. 

Phylum - - - - Chordata or Vertebrata 

Class Mammalia 

Order Primates 

Family - - - - - - Hominidae 

Genus ------- Homo 

Species - - sapiens 

The young of many insects and of some other animals cannot be 
placed in the proper species because animal life histories are very imper- 
fectly known. Such animals are merely placed in the proper genus or 
family. The common names of animals rarely apply to single species 
but to whole genera, families, or even orders. " Caddis- worm" is a name 
applied to a whole order of insect larvae and as these are very imper- 
fectly known the term caddis-worm is applied to many species, and, 
applied in this way, appears in many places in the text. 

Because of the large number of animals and the difl&culty in naming 
them, it is quite impossible to deal with the data in the specific way that 
might be possible with plants. Furthermore, while the data for plant 
distribution are not well known, those for animal distribution are much 
less well known. Therefore in most cases it is necessary to speak in 
general terms. It is impossible and undesirable to discuss each com- 
munity of animals in detail. The facts are not known, and even if they 
were known, their volume would be such as to exclude the great majority 
of them from the limits of this treatise. In most cases it is best to make 
a statement of the leading facts, and a few statements about the specific 
situations to give an idea of the kinds of animals that are characteristic 
or common there. It should be noted also that the most characteristic 
animals are often not generally known and are in some cases rare. 

The scientific names of characteristic and common animals are 
included, not so much for geographers at present, as to form a basis for 
further work and comparison by zoologists and zoogeographers. Where 
given in the form of tables they present the actual scientific background 
for the facts here stated. Much greater detail would be needed for a 
full zoological treatment. Scientific names are usually used where the 
common names apply to many species. The names of authors of species 
are added in the text and description of figures only where they do not 



INTRODUCTION 3 

appear in either the lists and tables or in the descriptions of figures. No 
attempt has been made to include the same animals in the text, tables, 
and illustrations, as the only aim has been to make each part as useful 
as possible. 

While the amount of work that might have been done along the lines 
here represented is infinite, this work represents only a general survey. 
The data are incomplete, but we believe them to be adequate for the 
purpose of illustrating the principles involved. Considerable experi- 
mental work has been conducted with reference to animal communities,' 
but it has served only as a background, and in comparing them we 
have relied upon comparison of (a) habitats and {b) species. The latter 
is fraught with many dangers, for it assumes, in the absence of evidence 
to the contrary, that the physiological character of a species is the same 
in the different situations in which it is taken. Observation has shown 
this to be true for most species within rather uncertain limits. There 
are, however, many well-known exceptions to this, some of which are cited 
in the text. Such use of species is certainly to be avoided in the study 
of the extensive or geographic distribution of animals, and it remains 
to be seen how far it may be employed locally. Certainly ecology cannot 
reach its best development if it relies upon such a method. Whatever 
further investigation may prove on this point, it is hoped at least that 
we may be ablo to suggest problems which may be attacked from new 
points of view. Should this object be accomplished, the work will have 
served its purpose. 

'The term community, as used here, refers to all the animals living in the same 
surroundings. 



CHAPTER I 

MAN AND ANIMALS 
I. Introduction 

I. CULTURE AND NATURE 

In this discussion we are concerned with nature and our relations to 
nature. 

Nature is an enormous aggregation of things — objects — each having cer- 
tain metes and bounds, certain qualities and powers, beyond which it cannot 
go. Now, knowledge of nature, sanity toward nature, consists exactly not only 
in ever increasing the extent of our inventory of these objects, but of recog- 
nizing, without addition or subtraction, that is, accurately and justly, the 
forms, the qualities, and the forces of these objects — what they are and what 
they are not; what they can do and what they cannot do. 

Is there anything worse than mild folly in the belief in the "sea serpent" ? 
That depends. If the belief involves the notion "monster," then yes, decidedly, 
for the belief is of the self-same kind that has prevented men from being sane, 
that has filled them with dread, in all ages. It is a question, not of nature, but 
of state of mind. The person whose mental attitude is such that he easily and 
unwittingly puts into the sea from his own consciousness a creature that does 
not exist in the sea, and holds it to be as real as those that do exist there, is 
also in a state of mind to attribute to all sorts of innocent creatures and persons 
qualities and powers they do not have and hold these powers to be as real as 
the ones they actually do possess. — Ritter (i).^ 

We have all heard of the octopus or devil-fish, with its long arms 
covered with powerful suckers, which is always waiting to seize the 
unsuspecting, choke and bite him, always grasping with another arm 
when the grip of one of them is loosened — suitable symbol of the trust. 

A person wading in the water among rocks where there are devil fishes is 
about as likely to be attacked and bitten by one of the animals as he is to be 
injured by the explosion of a watermelon, when walking through a melon patch. 
Both things are possible. 

The octopus secretes a great quantity of black fluid and makes use of this 
by squirting it into the water to envelop itself in "pitch darkness" against 
the approach of enemies. But the fluid is not poisonous, nor the leastwise 
injurious to anybody or to any creature, so far as we know. 

' Numbers in parentheses, scattered through this work, refer to references in the 
Bibliography at the end (pp. 325-36). 



6 MAN AND ANIMALS 

In short, the animal is not a "horrid thing," as it is painted in story and 
in many a dimly lighted imagination. There is nothing devilish about it. 

And here is the moral of the "devil fish " : If there is a corner of your mind 
that wants to attribute to the octopus malevolent qualities and powers that it 
does not possess, and is content to overlook or deny to it qualities and powers 
of interest and beauty that it does possess, mark my word, the same corner of 
your mind will tend to treat such at least of your fellow-men as you do not know 
well, in the same way. This unfortunate corner of your mind will, like all 
other corners, be true to itself — to its own qualities. It is the old impossibility 
of blowing hot and blowing cold at the same time. — Ritter (i). 

We may accept this as one of our relations to nature and general 
culture, and sanity toward nature as one of the benefits to be derived 
from study of science and nature. 

2. SCIENCE AND NATURE 

All biological problems are problems of nature. Evolution became a 
problem only when a large knowledge regarding the number and diversity 
of animal species had been acquired. This has been the problem around 
which most zoological facts have been accumulated. Indeed, most 
zoologists have little interest in problems not throwing light on evolution. 
The development of zoology has therefore been one-sided. Had geology 
clung as closely to the origin of the earth as zoology to evolution, it 
would not be the unified science which we see it today. The lack of 
unity in zoology has been caused in part by the neglect of the aspects 
which we are to take up here. In this connection, Thompson (2) has 
said of Brehm, one of the older students of natural history: " He [Brehm ] 
had unusual power as an observer of the habits of animals. His 
particular excellence is his power of observing and picturing animal 
life as it is lived in nature, without taking account of which, biology is 
a mockery, and any theory of evolution a one-sided dogma." It follows 
also that sanity in science is dependent upon a knowledge of nature. 
Our first steps in the task before us must accordingly be a consideration 
of wild nature as it really is. This can perhaps best be accomplished by 
comparing the reality with some of our conceptions of it. 

II. The Struggle in Nature 

The first step toward an understanding of our relation to nature, 
or rather the animals and animal communities of natural conditions, is 
to acquire a knowledge of the conditions of animals in a state of nature. 
There is much literature on this subject, but our conception of the 
struggle for existence and the survival of the fittest is too often entirely 



STRUGGLE IN NATURE .7 

forgotten when we are considering our relation to animals. Nature is 
cruel and heartless, and to die to become food of another organism is the 
fate of the vast majority of animals. Mr. Roosevelt has said: 

Watching the game, one was struck by the intensity and evanescence of 
their emotions. Civilized man now usually passes his life under conditions 
which eliminate the intensity of terror felt by his ancestors when death by 
violence was their normal end, and threatened them during every hour of the 
day and night. It is only in nightmares that the average dweller in civilized 
countries now undergoes the hideous horror which was the regular and frequent 
portion of his ages-vanished forefathers, and which is still an everyday incident 
in the lives of most wild creatures. But the dread is short-lived, and its 
horror vanishes with instantaneous rapidity. In these wilds the game dreaded 
the lion and the other flesh-eating beasts rather than man. We saw innumer- 
able kills of all the buck and of zebra, the neck usually being dislocated, it 
being evident that none of the lion's victims, not even the truculent wildebeeste 
or huge eland, had been able to make any fight against him. The game is 
ever on the alert against this greatest of foes, and every herd, almost every 
individual, is in imminent and deadly peril every few days or nights, and of 
course suffers in addition from countless false alarms. But no sooner is the 
danger over than the animals resume their feeding, or love-making, or their 
fighting among themselves. Two bucks will do battle the minute the herd has 
stopped running from the foe that has seized one of its number, and a buck 
resumes his love-making with ardor, in the brief interval between the first and 
second alarm from hunter or lion. Zebras will make much noise when one of 
their number has been killed; but their fright has vanished when once they 
begin their barking calls. 

Death by violence, death by cold, death by starvation — these are the 
normal endings of the stately and beautiful creatures of the wilderness. The 
sentimentalists who prattle about the peaceful life of nature do not realize its 
utter mercilessness; although all they would have to do would be to look at 
the birds in the winter woods, or even at the insects on a cold morning or cold 
evening. Life is hard and cruel for all the lower creatures, and for man also 
in what the sentimentalists call a "state of nature." The savage of today 
shows us what the fancied age of gold of our ancestors was really like; it was 
an age when hunger, cold, violence, and iron cruelty were the ordinary accom- 
paniments of life. If Matthew Arnold, when he expressed the wish to know 
the thoughts of earth's "vigorous, primitive" tribes of the past, had really 
desired an answer to his question, he would have done well to visit the homes of 
the existing representatives of his "vigorous, primitive" ancestors, and to 
watch them feasting on blood and guts; while as for the "pellucid and pure" 
feelings of his imaginary primitive maiden, they were those of any meek, cow- 
like creature who accepted marriage by purchase or of convenience, as a matter 
of course. — From African Game Trails, by Theodore Roosevelt; Copyright, 
1910, by Charles Scribner's Sons (3). 



.8 MAN AND ANIMALS 

III. Man's Relation to Nature 

Mr. Roosevelt's statement is quite diflferent from much of the poetry 
about nature, still it is a true picture. We live in a man-made nature 
from which the conspicuous animals and their deadly struggles have 
been eliminated (4, 5). Of the admirers of the beauties of nature I 
fancy that many, perhaps the majority, think of it as a series of lawn- 
like pastures, well-trimmed hedges, such as finds its ideal expression in 
some of the older countries like England. 

The trees, round, woolly, ready to be clipped; 
And if you seek for any wilderness 
You find, at best, a park, a Nature tamed 
And grown domestic like a barnyard fowl. 

— E. B. Browning, "Aurora Leigh." 

The close observer of nature, even in such man-made conditions as in 
Bedfordshire or in the Chicago parks, sees all the struggle which Mr. 
Roosevelt has depicted for the birds and mammals of primeval conditions. 
To kill is nature's first law. 

I. man's conduct toward animals 
There is much sentimental "nonsense about nature, about animals 
and cruelty to animals, as well as much actual cruelty and wanton 
destruction of useful animals. With some people birds obscure all else 
in the animal world. The destruction of squirrels, which are equally if 
not more interesting than birds, is sometimes advocated because of their 
alleged destruction of birds' eggs. The friend of the squirrel would 
plead equally hard for the destruction of certain hawks and owls as 
enemies of the squirrel. Certainly all lovers of the insect world might 
advocate the destruction of birds to protect their particular zoological 
pets. 

That birds save the harvests of every season is believed by many. 
The student of mammals is equally sure that certain mammals are the 
balance wheel, while the herpetologist is convinced of the importance of 
snakes, and the entomologist's economic world turns about predatory and 
parasitic insects and spiders. The fact is that each view, even thus 
extremely stated, contains its elements of truth. The whole truth is 
hardly knowable. Each animal is dependent upon many others. The 
dependences are so numerous that we find it necessary to isolate par- 
ticular animals and construct them into a society of real but limited 
relations for purposes of discussion (see p. 170). Still there are a few 
things that we can be reasonably sure of. The first is that we cannot 



MAN AND NATURE g 

interfere with any animals or the habitats of any animals without inter- 
fering with many others. The second is that all animals are of some 
economic importance. The third, that few animals can be said to be 
either wholly beneficial or wholly noxious, excepting those reared or 
preserved for their direct utility, and those directly and perniciously 
attacking the necessities of man's existence. 

Considering the first, we note that civilized man's operations interfere 
with animals and animal habitats. His first work is to destroy all large, 
dangerous animals. He clears and cultivates the land, bringing death 
and destruction to many more, and gradually substitutes domestic ani- 
mals for wild game ($a). Vegetarians often argue for the exclusive use 
of vegetable food on the ground that animals should not be killed, but 
to secure more plants for this purpose they of necessity would clear more 
land to grow more corn and thus destroy myriads of animals by methods 
more cruel than those of the butcher and huntsman. Our relations to 
animals are not simple, but very complex and our conduct often inconsist- 
ent. We cease wearing aigrettes because the collecting of them often 
leaves young birds to die, and kill every mouse and mole that happens 
to come our way, though their young must die as do those of the birds. 
Some of us wear leather shoes while arguing for a vegetarian diet because 
animals should not be cruelly slaughtered. 

Turning to the second and third ideas stated above, we note that 
few animals which feed upon a variety of foods, both plant and animal, 
can be said to be of any great usefulness, except when the plants eaten 
are useless to man. In other words, the good done the farmer by an 
animal which eats many insects, including noxious ones, may be offset 
by a destruction of grain. Birds eat a variety of food. Those feeding 
upon useful plants are not rated as of great economic importance. The 
bobolink, for example, eats grain and weed seeds in the spring when 
insects are scarce; soft-bodied insects in June and July when seeds are 
not available. In August the insects mature and are hard shelled. The 
birds now reject them for the grain seeds. This bird, furthermore, eats 
that which is available and most easily secured during the different 
seasons. This is also true of many, probably the vast majority of 
animals. The food of fishes is to a considerable extent determined by 
the kind of food available where they are living (6). Ruthven (7) has 
found this true of garter-snakes; the same is true of men. 

Many animals, birds (8), mammals, reptiles (9), toads (10), and 
insects destroy quantities of noxious insects, but along with them many 
insects that are enemies and parasites of the noxious ones are also 



10 MAN AND ANIMALS 

destroyed. The parasites, especially, are often more beneficial to man's 
interests than the animals which devour them, and which take good and 
bad without the slightest discrimination from our economic point of 
view. Because of their destruction of parasitic insects Severin (8) argues 
that birds should not be protected. Certain mammals and reptiles often 
show a decided superiority over certain birds in this respect, in that they 
are strictly predatory and are not directly noxious at any time of year 
as are some birds which feed upon grain. 

Many animals feed extensively upon insect pests when they are 
numerous and accordingly threaten a crop. This is true of spiders, 
insects (ii), amphibians, reptiles, mammals, and birds (8), especially 
those that are largely predatory. This fact is the only sure guaranty 
of the economic value of many birds, and is perhaps overworked by the 
fanciers of the group. This value belongs equally to certain insects, 
so that if birds were not devouring such insects along with pests, these 
hexapods would probably be able to put the pests down. The other 
vertebrates also would probably be able to put down the pest without 
the aid of the birds; Forbes has said that a balance would finally be 
reached if all the vertebrates were exterminated (see 26). 

In the preceding pages we mention "sanity toward nature." 
Sanity toward nature is based upon a full knowledge of available facts. 
Partial knowledge, if fully depended upon, is as dangerous as falsehood, 
for it leads to false interpretations. We must know nature, not a part, 
but the whole, if we wish to treat the simplest everyday problem of 
our relations to animals intelligently and justly. 

Why protect birds? Is the present attempt justified? In the 
answer to these questions all sentimentalism should be laid aside. It 
is sometimes urged that birds have a greater aesthetic value than other 
animals. This it seems is unjustified unless the songs of some constitute 
the justification. Persons with only a small acquaintance with insects, 
mollusks, fishes, amphibians, reptiles, and mammals find as much beauty 
in these groups as the bird fancier does in his. All groups should be 
preserved for their aesthetic value as the appreciation of it depends 
entirely upon temperament,' training, and especially a knowledge of the 

' A few persons known to the writer are repelled by birds because of their claws, 
scaly legs, and other reptilian characters. Many admirers o£ nature and animals are 
not attracted by birds because as a rule they must be seen from a distance. Inquiry 
at close range necessitates either shooting or capturing the bird and neither is a par- 
ticularly aesthetic operation. In the case of capture, only a short period of necessary 
neglect usually renders the surroundings and often also the bird not only not aesthetic 



MAN AND NATURE li 

group in question. From the economic viewpoint there is not a complete 
agreement as to bird protection. France does not co-operate with Eng- 
land in bird protection because her leaders in economic thought (Severin 
and others) have ably opposed it on economic grounds; still France is 
more progressive than England in agricultural matters. Other things 
being equal there are but two more reasons for special measures for the 
preservation of birds than for the preservation of reptiles, amphibians, 
or insects. First, birds are subject to destruction by reckless gunners. 
Second, they are less dependent upon natural conditions on the ground 
and are better able to survive after land has been put under cultivation 
than some other groups. Many other animals whose diets are varied 
have been exterminated or will be so by agriculture, leaving the birds 
as the most easy point for protective effort. The protection of birds 
should not be urged at the expense of the extermination of other animals 
because of their alleged occasional attacks upon birds. The great 
danger of acting on partial truth regarding animal interdependences 
makes societies for the protection of birds alone scientifically and educa- 
tionally unjustified. The protection of all groups should be urged, in 
particular through the preservation of the natural features upon which 
they depend. It is well to protect fishes from seiners and birds from 
gunners but this often only delays their fate. We must also consider 
where they will breed a few years hence. 

When one comes to love an animal or a group of animals, he is in 
no position to draw scientific conclusions regarding it. For this reason 
bird enthusiasts are not always to be trusted. It was the persistent 
efforts of such "benefactors" which gave us that detestable avian rat, 
the English sparrow, the feeding or sheltering of which is now a misde- 
meanor in some of our states. 

Should we slaughter animals ? As members of a system of nature in 
which to kill is the first law, we must answer in the affirmative. Man is 
the master of all destroyers. Where are the bison, the beaver, the elk, 
the thousand and one denizens of the primeval forest and prairie ? We 
scarcely walk over a path or lawn without bringing " death " and "suffer- 
ing" to animals of some sort. The crime of their destruction can be no 

but malodorous and repulsive. Thus to those who wish to examine objects closely 
other animals have a greater aesthetic value. Claims for a greater aesthetic value for 
birds must be based upon impressionistic appreciation of them in connection with 
landscape. There is no reason to desire or assume that this interest will decrease 
with time, but it is reasonable to suppose that with further dissemination of scientific 
ideas and methods among the people a comparable amount of more serious interest 
will develop in connection with other groups and perhaps with birds as well. 



12 MAN AND ANIMALS 

crime at all, in so far as the destruction is absolutely unavoidable. The 
wanton and useless destruction of animals not condemned as noxious by 
years of investigation, though probably not forbidden by the example 
of the animal world, is forbidden by the best sensibilities of every civilized 
man and woman. When the value of an animal to us is in question, the 
animal should have the benefit of the doubt, and we should hesitate 
long before introducing animals of supposed value. Certainly, also, 
every animal condemned by careful investigators should be destroyed 
whenever opportunity is presented. Mistaken and sentimental ideas 
cause the killing of many useful animals and the protection of many 
noxious ones. The farmer kills snakes and skunks whenever he has the 
opportunity, though they are among the most useful animals. Shrews 
are master destroyers of mice. Still many people mistake shrews for 
meadow mice and destroy them. Likewise the housewife kills the 
house centipede, the enemy of household pests, as a dangerous and 
repulsive creature even in the absence of any knowledge of the question- 
able charge that it bites young infants. Mistakes are not confined wholly 
to uninitiated individuals. Misjudgment by the officials of the Brook- 
lyn Institute of Arts and Sciences, possibly influenced by the sentiment 
of Longfellow's mistaken poem on the "Birds of Killing wor th " brought 
about one of the first official introductions of the English sparrow. Thus 
we see that the complexity of the problem demands careful study and 
conservative action. 

2. MAN-MADE COMMUNITIES 

Animal communities are divisible into primeval or primary com- 
munities, and man-made, or secondary communities (12, 13). As has 
been noted when civilized man enters a new territory, he first destroys 
all large game which threatens himself and his domestic animals. He 
then destroys the natural vegetation and other animals by clearing the 
timber, burning all woody debris, and plowing and putting out plants 
which are entirely new to the region. Under primeval conditions, 
plants are arranged irregularly, as roughly indicated by the letters in 
Diagram i ; after being put to agricultural purposes, they are arranged as 
in Diagram 2. The plants are all of one kind and are arranged in rows. 
A grove of the original vegetation is sometimes left. The rate at 
which these changes take place is directly related to the rate at which 
man occupies and cultivates the new territory. As compared with 
natural changes, this process is rapid and is accompanied by an equally 
rapid decline of primeval or primary communities. 



SECONDARY COMMUNITIES 



13 



heddeb hei cd efg cbe mi 
e mefg nm be de fg fgbn 
ghi be CO dp eqfr gohifb 
bdcviwhxgyfzembndoc e ih 
efgxny uinh fgbhjnk nsfg 
ghia dftghtyb hfj tkibhc 
sdftunmgkiuoht hyfgtrdcg 
dfgythufbnjks vdg fhtgry 
hfgt fhgty sdswaq nfhjdl 
ghtyuwiokp fbndhutbs gtu 
vdfxzabjfmua fgh yfs j i 
edfgrthfinbghb fgvnzxvcb 
erffghtjk vbxzzasxscdf ge 
thigjszxlkm, j hytfsdtrfb 

Diagram i. — Showing the arrange- 
ment of plants and animals on a plot of 
ground under primeval conditions. The 
letters are fortuitously chosen to rep- 
resent the fortuitous arrangement of 
plants and accordingly the animals as- 
sociated with them. Thus m, n, x, and 
z may be taken to represent oak, maple, 
basswood, and cherry, respectively, and 
the animals associated with each. The 
other letters may be taken to represent 
herbs and shrubs and the animals asso- 
ciated with them. 



edbeddgjcdbgdcgdcbedcdgebc 
f eceiejfadfeedefadfcecdede 
cbaaaaaaaaaaaaaacb 
edaaaaaaaaaaaaaaed 
fg aaaaaaaaaaaaaa fg 
dcaaaaaaaaaaaaaadc 
eb aaaaaaaaaaaaaa eb 
dg aaaaaaaaaaaaaa dg 
fd aaaaaaaaaaaaaa fd 
dc aaaaaaaaaaaaaa dc 

eg aaaaaaaaaaaaaa eg 
fci bedfg beg bdg ded jef gdj fc 
cgj cde fdedfdfebfcg 

Diagram 2. — Showing the arrange- 
ment under agricultural conditions. 
Here the plants which are put out in 
rows are represented by a's arranged in 
rows. There are certain animals asso- 
ciated with such plants and the a's rep- 
resent these also. Land is not usually 
cultivated close to the fences and thus 
each field is surrounded by a border of 
original shrubs, herbs, and sprouts from 
the original trees. These and the ani- 
mals associated with them are still for- 
tuitously arranged. 



3. THE DECLINE OF PRIMEVAL COMMUNITIES AT THE HEAD OF 
LAKE MICHIGAN 

By Mabel Brown Shelford 
When the white man first appeared near Chicago no secondary 
community existed, as the aborigines lived almost entirely by hunting 
and fishing. They cultivated the land only a little, and are accordingly 
to be ranked with the larger animals as a part of the original communities. 
The Indians of this region were chiefly Potawatomi, although there 
were a few Chippewas and Ottawas (14, 15)- Early in 1833 (15) about 
5,000 assembled in Chicago to treat for the sale of their entire remaining 
possessions in Illinois and Wisconsin. A treaty was finally ratified and 
in 1835-36 (14, 15) they left the region forever. They settled in Iowa 
for a time, but the advancing tide of civilization drove them 
farther and farther west. In 1890 (16) the larger part of the Pota- 
watomi, about 950, occupied land in Kansas and Oklahoma. The region 
about Chicago was particularly adapted to the life of the Indians, and 
it was probably an important region for them, as well as their successors. 
The innumerable water courses and ponds afforded an abundance of 



14 MAN AND ANIMALS 

muskrats, mussels, fish, etc., and the larger game of the land was par- 
ticularly abundant and diversified, because of the numerous habitats 
represented. Unfortunately, a fragmentary record is all we have of the 
decline of the primeval communities and the development of the present 
ones. These records apply mainly to the large animals of Cook County. 
The time of the disappearance from Southern Michigan, Northern 
Indiana, and Lake County, Illinois, was probably much later and, with 
the exception of the bison, bear, and elk, the more numerous kinds of 
game nearly all still occur in the thinly settled portions of Illinois (5a). 

The earliest explorers of this region, Marquette, LaSalle, and others, 
speak repeatedly of the great abundance of large game (17, p. 34). 
LaSalle, in the autumn of 1679, sailed along the western shore of Lake 
Michigan until the end of the lake was reached. Landing, he found deer, 
bear, and wild turkeys in great abundance. Grapevines loaded with 
clusters of ripe grapes hung from the tall forest trees and provided a rich 
feast for the bears. Continuing toward the headwaters of the Kankakee 
River, one stray buffalo was found sticking in a marsh. It was the 
beginning of winter and the remainder of the herd had probably migrated 
South, but on entering the headwaters of the Illinois River, in the autumn 
of the following year, LaSalle says that he found the great prairies 
"alive with buffalo" (18). 

• The Indians claimed that bison were very plentiful on the prairies 
until the Storm Spirit, becoming angry at the Indians, sent a great 
snowfall and very cold weather, which drove the buffaloes away and 
they never returned (19). The time of the great storm seems to have 
been between 1770 and 1780. There is good evidence, however, that 
they were found in considerable numbers in this part of the state as 
late as 1800 (20). Soon after this they entirely disappeared. As late 
as 1838 traces of them were still to be found in buffalo paths, well-beaten 
trails, leading generally from prairies in the interior of the state to margins 
of large rivers. These paths were very narrow, showing that the animals 
went in single file (20). 

In 1800 and for many years afterward, bears, deer, and elk, especially 
deer, were very plentiful. For some time deer continued to increase with 
the population because of the protection found in the neighborhood of 
man from the beasts of prey, and the gradual thinning-out of the animals 
which preyed upon them (21). Elk had almost entirely disappeared in 
1837, although a few were seen occasionally (22, 20, 20a, 23). John 
Reynolds, an early settler of Chicago, tells of being one of a hunting 
party that wounded an elk (20a). In 1837 bears were seldom seen (20, 



SECONDARY COMMUNITIES 15 

20a) . Panthers and wildcats were found occasionally in the forests ( 20a) . 
Beavers and otters, once numerous, had almost gone (20). Among the 
rodents, the varying hare disappeared about 1834. 

In 1838 timber wolves and coyotes were still numerous (20a). The 
deer was the most common prey of the timber wolf, but these failing, they 
attacked sheep, pigs, calves, poultry, and even young colts (20). For 
some time the increase of wolves kept pace with the increase of live 
stock. Reptiles were most common in the heavily timbered country. 
As this was cleared, they disappeared, while the prairie reptiles were 
destroyed largely by prairie fires. 

The coyote disappeared about 1844, while the timber wolf did not 
entirely disappear until about ten years later (22). The red fox, quite 
common at one time along Lake Michigan, also disappeared from this 
locality, about this time, although still found occasionally throughout 
the state. The gray fox, once quite common, was no longer to be seen 
after 1854 (22). The black bear and badger had entirely disappeared at 
the same date, although the latter was still common farther south (22). 
The fisher, formerly seen frequently in the heavy timber along Lake 
Michigan, was no longer to be found. The mink, skunk, otter, and 
weasel were still common (22). 

The pocket gopher and the badger, once very abundant, were very 
rare in 1854 (22). The Canada lynx and wildcat were still abundant, 
but of the panthers a single individual was known to have been seen in 
Cook County previous to 1854 (22). The decline and disappearance of the 
carnivores was followed by the greatest abundance of the deer. Accord- 
ing to Wood (21) the deer began to disappear from Central Illinois about 
1865 and had totally disappeared in 1870. Their disappearance from 
Cook County probably antedated this. The opossum, at one time not 
uncommon in this vicinity, was now rare except in Southern Illinois. 
The only trace left of beavers was the remains of their dams in several 
streams (22). 

4. RECOGNIZABLE SECONDARY COMMUNITIES 

We may recognize the following communities in the order of their 
degree of difference from the primeval ones: 

a) Communities of roadside, fence-row, and abandoned field vegetation. 
— These are composed chiefly of animals which commonly inhabit weeds 
and thickets along the edges of woods. Since these are most nearly 
like the thicket or forest-margin communities treated in chap, xiii, 
they are not discussed here. 



i6 MAN AND ANIMALS 

b) Communities of parks and pastures. — The ground and subterranean 
animals of both pastures and lawns are (near Chicago) chiefly such 
prairie animals as can live under the conditions of close grazing or close 
mowing. This type of community is probably better developed in 
the pastures than in the parks and lawns. The thirteen-lined squirrel, 
the May beetle grub, and the earthworms are among the common 
species. On the lawns a few grass-feeding species have a hazardous 
existence. On the pasture land prairie animals are more abundant, 
and an occasional prairie bird nests in a clump of weeds which the cattle 
have not eaten. 

Shrubs, when present, are inhabited by the forest-margin species. 
The trees present are inhabited by such forest animals as are able 
to live without the characteristic ground conditions of a forest and 
under the more severe atmospheric conditions. There are various 
facts pointing to a difference in the animals attacking trees differently 
located with respect to other trees; for example, trees standing alone 
in open pastures probably have a very different fauna from trees of 
the same species growing in the woods. This has not been fully investi- 
gated, however. The trees of the parks and lawns are often somewhat 
different from those of pastures, because of the introduction of many 
trees not native to the region. The animal communities of trees fre- 
quently include species introduced from Europe. 

c) Communities of lands devoted to cultivated annuals. — The communi- 
ties of farm lands are made up of animals from the prairies, the forest 
margin, and marsh vegetation, together with introduced species, such as 
the cabbage butterfly, the wheat aphis, the Hessian fly, etc. 

d) Communities of orchards. — The communities of fruit-growing lands 
are made up of the animals from the wild haw, wild crab, wild plum, and 
other forest trees, the greater number of which are commonest on flood- 
plains. There are also a number of introduced species. 

e) Communities of buildings. — 'The communities of barns, factories, 
and dwellings include the common bedbug (introduced), the silver fish, 
the cockroaches (introduced), various buffalo bugs of which several are 
introduced; one (Dermestes lardarius Linn.) is dangerous to stored 
materials and has been known to eat holes in lead pipe; while various 
spiders, centipedes, and camel crickets occur. The house mouse, the 
Norway rat, and the English sparrow have all been introduced. About 
75 household species are to be expected in and about Chicago. 

/) Communities of polluted waters. — 'In connection with the building 
of cities, we always find the introduction of sewage and industrial wastes 



SECONDARY COMMUNITIES 17 

(24) into streams, ponds, and lakes. The effect of the industrial wastes 
differs with their character. Sewage practically destroys all the life of a 
stream or lake near the point of entrance, through the introduction of 
many poisonous substances, through the increase of carbon dioxide 
and ammonia and through the lowering of oxygen content. Nichols (25) 
states that the oxygen above the entrance of the Paris sewer into the 
Seine was 9. 23 c.c. per liter, and immediately below i .05 c.c. per liter, a 
reduction of almost 90 per cent. The typical swift-water fauna of Thorn 
Creek at Thornton was reduced to practically nil by the opening of 
the Chicago Heights sewage system. The common isopod {Asellus com- 
munis) was the only animal able to withstand the conditions. At a 
distance from a point of entrance of sewage the amount of plankton 
is increased by its introduction because of the nitrogen and other food 
for plants which it contains. Forbes (see 5a) reports that the amount 
of plankton near Havana in the Illinois River has doubled since the 
opening of the Drainage Canal. 

5. EQUILIBRIUM IN THE SECONDARY COMMUNITIES 

Equilibration means a restoration of balance in the numbers of 
contending organisms of the community. For instance, as has already 
been noted, the deer reached their maximum number with the correspond- 
ing destruction of the carnivores by man. This indicated that the 
primeval balance between the carnivores and the herbivores had been 
disturbed. An entirely new balance has now been established through 
the complete destruction of both the large her^ifebres and carnivores, 
by man. Most of our knowledge of equilibration in communities has 
resulted from the study of the secondary communities of parks and 
agricultural lands. Concerning these Forbes (26, p. 15) has said: 

There is a general consent that primeval nature, as in the uninhabited forest 
or the untitled plain, presents a settled harmony of interaction among organic 
groups which is in strong contrast with the many serious maladjustments of 
plants and animals found in countries occupied by man. [All our serious out- 
breaks of insect pests are instances of these maladjustments.] 

To man, as to nature at large, the question of adjustment is of vast impor- 
tance, since the eminently destructive species are the widely oscillating ones. 
Those insects which are well adjusted to their environments, organic and inor- 
ganic, are either harmless or inflict but moderate injury (our ordinary crickets 
and grasshoppers are examples); whUe those that are imperfectly adjusted, 
whose numbers are, therefore, subject to wide fluctuations, like the Colorado 
grasshopper, the chinch bug, and the army worm, are the enemies which we 
have reason to dread. Man should then especially address his efforts, first. 



l8 MAN AND ANIMALS 

to prevent any unnecessary disturbance of the settled order of the life of his 
region which will convert relatively stationary species into widely oscillating 
ones; second, to destroy or render stationary all the oscillating species injurious 
to him ; or, failing in this, to restrict their oscillations within the narrowest limits 
possible. For example, remembering that every species oscillates to some 
extent and is held to relatively constant numbers by the joint action of several 
restraining forces, we see that the removal or weakening of any check or barrier 
is sufficient to widen and intensify this dangerous oscillation, and may even 
convert a perfectly harmless species into a frightful pest. 

Forbes mentions that cottony scale, a common pest in our parks, 
was rare in natural conditions. The close setting of trees has favored 
its increase. Close setting is nearly always a factor which has to be 
considered. 

How do pests arise? The recent rise of the wheat aphis may be 
taken as an example. The spring of 1907 was very warm in the southern 
part of the wheat belt, and the grain aphis, which is said to reproduce 
freely at temperatures from 100° F. to below freezing, was accordingly 
able to reproduce without interruption from its parasites and enemies, 
which do not become active at such low temperatures as occurred. 
When the weather grew warmer and the enemies appeared the aphids 
were so numerous that the work of the enemies was hardly appreciable. 
But since they too, like the aphids, are rapid reproducers, with such 
favorable conditions they were able to increase rapidly. With their great 
increase the aphids decreased and soon their numbers were far too great 
for the available aphid food. The enemies therefore decreased because 
of the absence of sufficient food, and this portion of the society was 
accordingly restored to an approximate equilibrium. It is to be under- 
stood that such an oscillation in the society is far-reaching in its effects. 
It has been noted that such oscillations affect the whole community. 
The birds and mammals find certain kinds of food abundant and accord- 
ingly eat things different from what they do under different conditions. 
Such fluctuations in the animal communities are constantly going on. 

The whole process may be summarized as follows : 

1. Weather conditions unfavorable to enemies and favorable to plant pest. 

2. Increase in pest. 

3. Increase in enemies. 

4. Decrease in pest. 

5. Decrease in enemies. 

6. Balance. 



SECONDARY COMMUNITIES 19 

6. DISTRIBUTION OF SECONDARY COMMUNITIES ABOUT CITIES 
AND VILLAGES 

The secondary communities of the regions about Chicago are those 
typical of the forest-border area; some of them are found throughout 
the temperate world. The communities in and about cities are not 
particularly different from those discussed in general terms in the pre- 
ceding pages. This is a topic for special study and we can give but the 
briefest outline here. 

When a city is in the village stage the communities of barns and 
dwellings are crowded together and the area of cultivated land and park 
is proportionally larger than in the country. As a village grows into a 
city, usually a central area of business houses, factories, and cheap tene- 
ments, dominated by the communities of dwellings, succeeds, practically 
all others being excluded. This type usually radiates from this center 
for a short distance along the principal lines of railroad and river trans- 
portation. Except for these narrow radiations, the central business 
section is surrounded by a belt of residences, which are of the park-lawn 
type, usually with the garden or cultivated type very much reduced 
or entirely eliminated. This type extends outward along all lines of 
passenger transportation. Toward the outskirts of this, and often 
quite irregularly arranged, are vacant lots and squares allowed to grow 
up to weeds and shrubs, and which are usually occupied by forest- 
margin animals. Outside of and adjoining these is the area of market 
gardening on the lower and better soils. Other types of agricultural 
land are usually poorly cultivated in the vicinity of cities. 

A succession of conditions dominated by one or another of the second- 
ary communities may be seen as the pioneer farm passes into the city 
stage. The pioneer-farm type is succeeded by the village type, with its 
park-lawn and dwelling combination. The village gives way to the 
business center, dominated by the "dwelling" animals. As these pro- 
cesses take place, a succession of the various grades of human society is 
noticeable. In dwellings probably the first resident pest is the clothes 
moth. This is probably succeeded by the silver fish and an occasional 
cockroach before the succession of the various grades of society has 
begun. Cracks appear in the woodwork as the building becomes 
"run down," and the introduction of a lower grade of society begins. 
The bedbug next makes its appearance and marks the beginning of a 
rapid lowering of standards on the part of occupants. The house mouse 
makes its appearance and is followed later by rats and vermin which 
mark the final stages in the degeneration into a cheap tenement. 



20 MAN AND ANIMALS 

IV. The Economic Importance of Animals 

Why study bugs ? Why waste your time upon that which can bring 
in no money? Why study insects, worms, birds, or snakes? These 
are questions which are often asked of the zoologist, especially such as 
go into the field to study and collect animals and accordingly meet the 
public. They are questions which the zoologist seldom can answer to 
the satisfaction of the inquirer, who not infrequently thinks the observer, 
if alone, is somewhat insane. Indeed, the conduct of one Chicago 
entomologist led to a police inquiry into his sanity. His offense was that 
of collecting insects under an electric light. The questions above we 
shall not attempt to answer here, except by asking, "Why study any- 
thing?" 

We have already noted the complexity of the problems of our relation 
to nature. We have noted the disturbed balance, the ravages of species 
introduced by accident and by official act. We have noted that knowl- 
edge is necessary as a basis for "sanity toward nature." We have still 
to call attention to some of the economic values of animals. 

It follows from the nature of the animal community and the close 
interdependence of the various species that every species is of some 
importance in the chain of food, space, and other relations, and every 
species is therefore of some economic importance. A few are of great 
economic importance. In addition to this we have certain definite 
practical uses and well-known matters of importance attached to each of 
the animal groups. Taking the various groups in their taxonomic order, 
we note the following: 

The protozoa are one of the important sources of food of larger forms. 
Also about a half-dozen human diseases are known (27) to be due to them, 
and the list is continually growing. The shells of extinct species are 
an important part of chalk. 

The uses of sponges are familiar. Aside from their importance as 
food of other forms, the coelenterates furnish us with corals of all sorts. 
Among the echinoderms the starfish is an important enemy of the oyster 
and mussel beds (28). The flatworms are important as parasites, many 
species having been recorded in the body of man (29). The round worms 
are of considerable importance in the same way, and some are serious 
enemies of grain. The earthworms are of much value to the soil (30). 
The crustaceans are the most important aquatic invertebrates, the 
Entomostraca being, from the standpoint of food supply, to the waters 
what rooted plants are on the land, one of the things to which nearly all 
food interaction can be traced. Some are used as food (lobsters, shrimps, 



USEFUL AND NOXIOUS ANIMALS 21 

crabs). Some are quite extensively used as fertilizers (horseshoe crabs). 
The mollusks, aside from importance to other animals, give us our pearls, 
pearl buttons, shell work of all kinds (31), fertilizers, important food, ink, 
cuttlebone, etc. (32). 

The insects are of such importance that nearly every state and 
civilized country maintains an expensive staff of trained men whose 
business it is to advise the public in regard to their treatment and to 
investigate the relations of insects to industry. Their ravages or fear 
of the same are the basis of some of the speculation which enriches some 
and pauperizes other speculators in the necessities of human life. Aside 
from this we have the numerous products from insects — tincture of 
cantharides, honey, wax, lac (33), carmine (34), and cochineal. Many 
are used as human food in the tropics (locusts, water-bugs, flies, larvae 
of the palm weevil, etc.). Some few, such as the scorpions, are poisonous. 
Many diseases are known to be carried from person to person by insects 
and arachnids (cholera, yellow fever, malaria, sleeping sickness, typhoid, 
typhus, bubonic plague, mountain fever, perhaps leprosy) as well as a 
great host of larger parasites. 

We turn now to the vertebrates, which are familiar and their uses 
quite well known. From this group we get our leather, furs, animal 
oils (snake oil, fish oil, turtle oil, lard, whale oil, skunk oil, woodchuck 
oil, neatsfoot oil), all of which have recognition in the markets and some 
of which have peculiar properties which adapt them to particular pur- 
poses (32). Glue, gelatin, bone meal, fertilizers, bone black, etc., are 
extensively used in industries; meats, dairy products, furs, leather, etc., 
are necessities. 

We must not, however, fail to call attention to animals as the basis 
for nearly all experimental study of life processes, of heredity, of behavior 
and psychology, of diseases and their cure and prevention. The public 
should disabuse itself of the idea that biological investigators are wasting 
their time on bugs, for lower animals are the only material upon which 
the problems of our race can be solved, and until we are prepared to sub- 
mit ourselves to be used in the solution of our own problems, biologists 
will be compelled to use lower animals as material. 



CHAPTER II 

THE ANIMAL ORGANISM AND ITS ENVIRONMENTAL RELATIONS 

I. Nature of Living Substance 

• The bodies of living plants and animals are made up of living matter 
known as protoplasm (35, chap. ii). Protoplasm is a chemical substance 
or a mixture of chemical substances. It is very difficult to distinguish 
living and non-living matter by definition. However, we experience 
little difficulty in separating living from non-living things. This is 
because living things usually possess certain definite forms and ability to 
reproduce and move (especially animals). They also possess irritability. 
This is the property by virtue of which the force applied to living sub- 
stance is not in proportion to the force resulting (35, p. 124). One 
strikes a horse with a whip; the energy which the horse exerts in running 
is not proportional to the force of the blow, but is far greater. 

In considering the environmental relations of animals, we shall 
separate our discussion into that concerned with form and that con- 
cerned with movement (motor activity) and other functional manifesta- 
tions. The term function is understood to cover all action on the part 
of the various parts of the organisms, motor activity included (35a, 
chaps, vii, viii, and ix). 

II. The Relation of Form or Structure to Function 

The term animal calls forth a mental picture of activity and 
movement. The animals with which we are most familiar are those of 
large size, such as fishes, birds, and mammals. They and the groups 
to which they belong represent only a very small part of the animal 
kingdom, but we may consider one of these familiar animals as an 
example of animals in general. The black bass will serve our purpose. 

Such a fish is a complicated, highly organized animal (36, p. 183), 
possessing many organs, such as fins, gills, teeth, a stomach, an intestine, 
a liver, a heart, and a brain and spinal cord harnessed to the rest of the 
body by a series of small nerves which control all the organs. The fins, 
which are the external organs of locomotion, are sufficient in number to 
control the body and force it forward. The muscles which move the 
fins must receive nourishment in order to do their work. The nourish- 
ment is carried in blood-vessels, and the fluid which bears the nourish- 



STRUCTURE AND ENVIRONMENT 23 

ment is propelled by the heart, which is an organ possessing definite 
form and a certain type of activity. In the case of a complex animal 
like the black bass, we might elaborate upon the relations of form and 
structure to activity and function almost indefinitely. It is obvious 
that the two features are related in the bass. When we consider animals 
which possess less elaborate structure, the relations become less obvious 
upon mere inspection because organs are less clearly differentiated, but 
they are still more easily demonstrable through methods employed by 
the biologist. 

In both the lower and the higher organisms, structure may be con- 
trolled by activity. If one cuts off the posterior end or tail of a flat- 
worm, a new tail is formed. Professor Child (37) found that if the 
animals were permitted to crawl on the bottom of the containing vessels 
while the new part was growing, the tail was pointed. If they were not 
allowed to crawl, the tail was rounded. There are many other pieces 
of experimental work which show that structure may be modified by 
function. In but few cases, however, has the modified structure been 
found to be inherited. 

At present the relations between function and structure have not 
been investigated in many cases, but Child has made their relation 
quite clear by comparing the organism to a river. "The relation between 
structure and function in the organism is similar in character to the 
relation between the river as an energetic process and its banks and 
channel. From the moment that the river began to flow it began to 
produce structural configurations in its environment, the products of 
its activity accumulated in certain places and modified its flow." It 
deposits and removes, and thus continually "moulds its banks and 
bottom, forming here a bar, there an island, here a bay, there a point 
of land, but still flowing on, though its course, its speed, its depth, the 
character of the substances which it carries in suspension and in solution 
all are altered by the structural conditions which it has built up by its 
own past activity" (37a). Thus we see that function and structure are 
mutually interactive and mutually interrelated, and, for the sake of 
clearness only, we shall separate the two rather sharply in our discussion. 

III. The Basis for the Organization of Ecology 

We have already noted that ecology deals with animal life as lived in 
nature, or, in other words, with the relations of animals to their environ- 
ments. The question of what aspects of these relations are most im- 
portant and best suited as a basis for the organization of ecology at 



24 ENVIRONMENTAL RELATIONS 

once confronts us. The selection of the basis for organization is the most 
important step before us, because if we may judge from the history of 
previous attempts, success or failure depends upon this selection. It 
appears from the preceding pages that we must choose between emphasiz- 
ing structure and form on the one hand, and function and activity on 
the other. 

I. FORM AND STRUCTURE IN RELATION TO ENVIRONMENT 

Each article of furniture in the room where I am sitting, each gar- 
ment which I am wearing, and the watch in my pocket were made for 
a purpose, and are adapted to the purpose for which they were made. 
This is so generally true of everything with which we have to do in our 
daily lives that we come to think of the phenomena of nature in the same 
terms, often without stopping to consider whether or not it can be true 
of nature. 

The reading into nature of the idea of purpose and of adaptation has 
been a common thing since the earliest records of science (38, pp. 52-56). 
Two centuries ago the idea that animals were created to fit their 
particular place in nature, just as a watch is made for a purpose, was the 
idea held by scientists; indeed, such is often the idea of non-scientific 
people today. Later, Lamarck conceived the idea that the animal was 
not necessarily adapted to a given place, but became adapted to such a 
place by trying to live in that place, or, while not able to do a certain 
thing, became structurally able to do that thing by trying to do it, just 
as the flatworm's tail becomes pointed, and the blacksmith's arm becomes 
strong through use. Lamarck (38, p. 169; 39, chap, vi) believed that 
the changes brought about by the uses which the organism made of its 
parts were inherited, but science has found chiefly evidence that such 
changes in structure are not inherited, and this idea of the origin of 
adaptation has been quite generally rejected. 

Following Lamarck came Darwin, who conceived the idea that all 
the individuals of a species which came into existence were not equally 
adapted to the mode of life that was necessary for them and those best 
adapted survived. Their characters, being born with the individual, 
were inheritable and the adaptation of species to which the individuals 
belong became perfected through the destruction of the unadapted. 
The destruction of the- poorly adapted and the survival of the best 
adapted is called "natural selection" or the "survival of the fittest." 

Following Darwin, a large number of investigators set to work to 
apply his theory to the phenomena of nature in detail. The ideas of 



STRUCTURE AND ENVIRONMENT 25 

"protective resemblance," "mimicry," and "warning coloration" were 
developed (40). The idea of protective resemblance is as follows: A 
certain insect is green and lives on green leaves. The natural-selection 
observer at once theorizes to the effect that the animal is green because, 
at a time when not all the individuals of that species were green, the 
birds secured all those not green and left the green ones because they 
were difficult to see; now therefore only green ones occur. In the case 
of mimicry, one species of insect (or other animal) resembles another. 
The theorist finds or thinks that one of them is distasteful to birds and 
other animals. He further discovers or concludes that the species not 
having a bad odor or taste is not eaten. by enemies because it resembles 
the distasteful species. The species having the bad odor or taste is the 
model. The species not having the bad odor or taste is the mimic. 
The mimic arose and attained its perfection because those individuals of 
the mimic species which resembled the model species survived. 

In the case of warning coloration, the animal supposed to be dis- 
tasteful has bright colors. The birds, learning that certain bright 
colors are associated with bad tastes, avoid such strikingly colored forms. 
Accordingly, the most brilliantly colored distasteful forms survive. 

More detailed study in recent years has tended to show such specula- 
tions to be of questionable value. Such ideas must remain matters of 
speculation at present, because of the difficulty of applying experimental 
methods to their study. Based on a theory with few facts to support it, 
and not withstanding critical analysis, the ideas of structural adaptation, 
including any of the ideas just mentioned, are not a good basis for the 
organization of a science of ecology. 

The revival of an old idea that animal species arose in places and 
by methods unknown, and by chance found places to which they were 
adapted, now constitutes the central idea of the most recent theory of 
the origin of adaptation and is to be favored as a working hypothesis, 
because it may be tested experimentally (41). 

Another reason for the inadvisability of attempting to organize 
ecology on the basis of structure lies in the fact that structural changes 
resulting from stimulation by the environment are rarely of advantage 
or disadvantage to the animal, and further that the structure of motile 
animals is not readily modified by the environment. A considerable 
number of animals are larger or smaller, lighter or darker, according 
to conditions surrounding them during development (42), but few 
biologists see any advantage or disadvantage to the animal in these 
changes. 



a6 ENVIRONMENTAL RELATIONS 

2. FUNCTION AND ACTIVITIES IN RELATION TO ENVIRONMENT 

We have just noted that from the point of view of structural adapta- 
tion, structure cannot be separated from function. It is equally true 
that from the point of view of physiology, function and behavior cannot 
be separated from structure. 

Turning again to the black bass, which we have already used to 
illustrate some points, we note that for the simple act of swimming, the 
digestive tract, gills, heart, blood-vessels, brain, and muscles are neces- 
sary. They must all be present to furnish the animal with the necessary 
energy and impulses to make motions for swimming. It is obvious that 
there is a division of labor between the different organs, and if any of 
them are impaired or injured, or interfered with, the work cannot go on 
in its proper manner, or perhaps not at all. The organism is a complex 
of correlated parts and processes. If we interfere with any of these, e.g., 
the circulation of the blood of the fish, which might be done in many 
ways, the whole system of interdependent processes is interfered with. 
The fish is a highly organized animal, but the same general laws of 
relations of processes, such as respiration, circulation of food materials, 
digestion, etc., apply to animals in which there are no special or definite 
organs to take care of each separate process. The interdependence of 
processes in the organism is sometimes called physiological proportionality 
(37a), i.e., the work accomplished by any one set of organs or processes 
is proportional to that of another set or all the sets of processes in the 
organism. When the processes are going on in perfect accord and in 
proper proportionality, the organism is said to be in physiological equilib- 
rium. The conception of the organism stated above may best be used 
in considering the relations of animal activities and functions to the 
environment. 

It is generally held that the various animal forms are made up of 
different kinds of protoplasm and that the eggs of no two species are 
alike as to protoplasmic character. They may differ only slightly in 
appearance, as for example the eggs of a frog and of a salamander, but 
even if the eggs of these two animals are laid in the same pool at the 
same time, and the conditions are essentially the same surrounding the 
two masses, one mass of eggs develops into frogs and the other into 
salamanders (43, p. 8). The only logical conclusion is that the composi- 
tion or protoplasm of the eggs is different. 

It must be noted at the outset, therefore, that different organisms are 
made up of different kinds of protoplasm; furthermore, combinations of 



ACTIVITV AND ENVIRONMENT 27 

the same living substances into different special organs would of necessity 
give different organisms different properties. 

Different chemical substances often behave differently under a given 
condition of temperature, pressure, or light, etc. Likewise, if a cockroach 
and a house fly are liberated in the center of a room, the fly goes to a 
window and the cockroach into a shadow; furthermore, a cold night wUl 
kill the house fly, while to dispose of the cockroach the proverbial two 
wooden blocks are necessary. Both differences in physiological char- 
acter (behavior) are due to differences in the organisms. Different 
organisms often behave differently in the same intensity of the same 
physical factor, for example, the same temperature or light, just as the 
different chemical substances do. Different chemical substances often 
undergo different changes with variations in temperature, pressure, or 
light. Each has its characteristic reactions. Still whole groups may be- 
have quite similarly. Changes in conditions affect organisms. We have 
all noted the effect of a cool day upon the activity of animals such as the 
insects. Different organisms usually behave differently in some respects, 
while whole communities may behave quite similarly in other respects. 

a) The organism as unaffected by the environment. — When all of the 
external conditions continue approximately the same, the activities of 
the organism are called spontaneous (35, p. 347). As has been stated, 
the organism is naturally active. Accordingly, movements may possibly 
take place as a manifestation of the released energy inside the animal, 
or of disturbances and changes in the organism which are not directly 
initiated by the environment. Probably animals often move without 
any external stimulation (44, chap. xvi). One who has observed the 
wonderful Japanese dancing mice knows that their constant movement 
may not be the result of the external conditions, but of the energy which 
is expended within the organism. 

Jennings (44) stated that these spontaneous movements must be 
recognized in the study of behavior, and that many errors have arisen 
from their neglect. If we see an animal moving, we should not assume 
that it is moving because of some external condition acting on it at the 
time. It may be due to previous stimulation or it may be the result 
of internal conditions. Growth, maturity, reproduction, and death are 
accompanied by changes in behavior, structure, etc. All may take place 
without great change in environment. 

b) The organism as affected by the environment. — Many organisms are 
not sensitive to slight changes in the external environment. Having 



28 ENVIRONMENTAL RELATIONS 

developed in, and never having been separated from, fluctuating con- 
ditions, they do not respond to all environmental fluctuations. The 
terms approximately constant and spontaneous used above are then 
both relative. Any change in the external conditions sufficient to alter 
the internal processes of the organism is called a stimulus. The visible 
movement of the organism or other phenomena resulting from stimulation 
is called the reaction. The reaction may be: {a) cessation of movement, 
{b) initiation of movement, or (c) change in kind or direction of 
movement. 

Fluctuations in the environmental conditions in nature usually 
involve more than one factor. Experiments are necessary to determine 
which factor is affecting the activities of the animal. The effect of the 
various factors taken singly upon a few animals has been determined. 
These factors are pressure, including currents and contact with other 
bodies, shock, vibrations and sound, temperature, water, chemicals, light, 
etc. For example, if we lower the temperature surrounding an insect 
sufficiently, it will become apparently stiff and lifeless (35, p. 396). If the 
temperature is raised again, the animal becomes active. The activity is 
increased as the temperature is raised until a degree of heat nearly high 
enough to kill it is reached, when the animal becomes inactive again. If 
the temperature is raised only a little more, the animal dies. In general 
changes in any factor produce either excitation or depression, or in 
other words, an acceleration or retardation of the activities. In con- 
nection with the acceleration or retardation of activity, animals fre- 
quently turn toward or away from the source of light or sound, or in the 
direction of a current of air or water. Or they congregate at a point 
where the temperature or the light or the chemical conditions interfere 
least with their internal processes. 

Such turnings or congregations are called tropisms or taxes (45). If 
the animals turn toward or go toward the source of stimulation they are 
said to be positive. If they turn away or go away or congregate at a 
distance they are called negative. The names applied to the reactions 
are given below. There are various theories as to the exact manner in 
which these turnings and congregations are brought about, but, as a 
rule, animals congregate where their internal processes are least inter- 
fered with, and random movements nearly always play some part in 
the process. There are two sets of terms applied to such responses 
as described above; they are given in parallel columns below (p. 29). 
Taxis means arrangement. Tropism means turning. 



ACTIVITY AND ENVIRONMENT 



29 



Reactions to light are called 

" temperature are called 

" moisture are called 

" gravitation are called 

" chemicals are called 

" contact are called 

" pressure are called 

" electric currents 

" current in medium 



phototaxis or heliotropism 



thermotaxis " thermotropism 

hydrotaxis " hydrotropism 

geotaxis " geotropism 

chemotaxis " chemotropism 

thigmotaxis '' stereotropism 

barotaxis " barotropism 

galvanotaxis " galvanotropism 

rheotaxis " rheotropism 

If we place a number of common pond snails in a dish which is dark 
at one end and grades to sunlight at the other, we find that most of the 
snails are found after a time in faint light. The explanation of this 
phenomenon is that the snails are stimulated by intense light and by 
very weak light, i.e., either of these conditions of illumination interferes 
with some of the internal processes of the animal, and the random 
movements which result bring the animal into various conditions, one of 
which (faint light) relieves the disturbance. The animal then ceases to 
move at random, because its internal processes are no longer interfered 
with by the stimulus. The snail's activity is lessened, or it turns back 
from regions of either too strong or too weak light; accordingly, most of 
the snails are found in faint light. The internal processes have been 
adjusted or regulated. The snails are said to be negatively phototactic to 
strong light and positively phototactic to weak light. 

The animal lives in an environment which is constantly changing. 
Its spontaneous movements are constantly bringing it into different 
conditions. It tends to regulate its internal processes by selecting the 
point in the environment in which its internal processes are not dis- 
turbed. The writer has observed snails in ponds. They move into their 
optimum light, i.e., the light which does not disturb them. On dark 
days they are found in the light. On sunny days they are found in the 
shade of the vegetation. They shift their position according to condi- 
tions and their distribution at any given time is a better index of 
conditions than the distribution of plants in the same pond. 

c) Modifiability of behavior and different physiological states. — We all 
know that our actions may be modified by experience. There are but 
few people who have not been greatly frightened by some accident 
accompanied by a characteristic noise. For days afterward, one starts 
at the slightest unexpected noise. His response has been modified. 
It is a well-known fact in animal training that an animal may be 
"spoiled." A horse may be ruined for some purposes by an accident. 



30 ENVIRONMENTAL RELATIONS 

which has caused it to run away, for it thereby acquires the habit of 
running away. In the lower animals we find the same condition; their 
behavior may be modified, but the modifications are less permanent 
than in man and other mammals. 

Changes within the organism cause approximately fixed environ- 
mental conditions to act as stimuli. Changes are going on all the time 
within the organism. Such changes may result from growth, maturation 
of sexual products, or other causes. The organism may be in physiologi- 
cal equilibrium (see p. 26) in a given set of conditions before the devel- 
opment of the eggs and spermatozoa begins, but these processes are 
accompanied by other great physiological changes, which frequently put 
the animal out of adjustment to its surroundings. 

The queen ant is in physiological equilibrium in the darkness of the 
nest until she becomes sexually mature. She then becomes positively 
phototactic, goes toward the light, flies from the nest with the males, 
and, being negatively geotactic, stays away from the ground. When fer- 
tilized, she at once becomes negatively phototactic, positively geotactic, 
and positively thigmotactic. Accordingly she places her body in contact 
with the ground, and burrows into it and starts a new colony. The ant 
is then in a different physiological state after becoming sexually mature, 
and in a third state after fertilization. 

3. ENVIRONMENTAL CHANGES 

a) Daily changes. — The physiological responses of animals to these 
changes have an important bearing on their relation to each other. 
Some forms are diurnal, others nocturnal, others crepuscular. Some are 
probably active all the time, but move into different positions in the day 
and in the night. For example, some pelagic animals (which float or 
swim freely in water and are independent of bottom) are numerous near 
the surface at night, but migrate to considerable depths during the day, 
as a response to light. Many animals bear relations to day and night, 
which in some cases may be of an adaptive character. Some forms are 
active during the day, and hide themselves during the night, either in 
burrows or under suitable objects. Those which simply crawl under 
loose objects during the day frequently appear at artificial lights in 
the evening. 

It is not impossible that there are structures in the bodies of many 
animals which are the product of the different conditions of day and night 
during critical periods of growth. Thus Riddle (46) has found that the 
barrings of the feathers of certain birds are due to low blood pressure at 
night (feeble circulation) during the growth of the feathers. 



HABITAT PREFERENCE 31 

b) Seasonal changes. — These involve great changes in the physio- 
logical states. Inactivity is the rule in winter; growth and activity in 
the other seasons. The plants and animals of a locality do not all reach 
sexual maturity or the greatest growth activity at the same time during 
the growing season, but different species succeed each other as the season 
advances (47). The food and enemies of a given species, which is present 
in an animal community for a large part of the growing season, differ 
from time to time. 

c) Weather changes. — These constitute fluctuations of conditions 
calling forth special types of behavior. Some animals hide when the 
wind begins to blow; some burrow into the ground on cool and cloudy 
days. 

4. HABITAT PREFERENCES 

By virtue of being unlike or possessing different properties, the various 
animal species require different conditions for the best adjustment 
of their internal processes. For example, the carp lives in shallow and 
muddy ponds and rivers, while the brook trout lives only in clear swift 
streams. These two organisms are able to move about and find places 
to which they are suited. The differences between them are clearly 
indicated by the differences in the habitats which they prefer. 

By observation and by experimentation it has been shown that 
animals select their habitats. By this we do not mean that the animal 
reasons, but that selection results from regulatory behavior (p. 29). 
The animal usually tries a number of situations as a result of random 
movements, and stays in the set of conditions in which its physiological 
processes are least interfered with. This process is called selection by 
trial and error. If animals are placed in situations where a number of 
conditions are equally available, they will almost always be found living 
in or staying most of the time in one of the places. The only reason to 
be assigned for this unequal or local distribution of the animals is that 
they are not in physiological equilibrium in all the places. However, 
some animals move about so much that it is with some difficulty that we 
determine what their true habitats are. 

5. THE MOST IMPORTANT ACTIVITIES OF ANIMALS 

Animal activities are classified as feeding, breeding, hiding, sleeping, 
etc. The strength of a chain is the strength of its weakest link; the 
activity which determines the range of conditions under which a species 
will be successful is the activity which takes place within the narrowest 
limits. This is usually the breeding activity. The breeding instincts 



32 ENVIRONMENTAL RELATIONS 

are the center about which all other activities of the organism rotate, 
and the breeding-place is the axis of the environmental relations of the 
organism (6, 48, 49, 50). Migratory birds are our most striking motile 
forms. They may migrate great distances, but always come back to the 
same kind of area to breed. 

Failure to recognize the relative importance of the different activities 
is in part responsible for the general unorganized state of our knowledge 
of natural history. Investigators have often failed to interpret the 
relations of animals to their environments because they have regarded 
the records of the occurrence of all stages of the life history as equally 
important. They have considered the occurrence of the most motile 
stage in the life history as significant, for example the occurrence of an 
adult butterfly. Plant ecologists would have met with equal success if 
they had studied only the environmental relations and distribution of 
wind-disseminated seeds. 

We have noted reasons for not putting primary emphasis on structure 
and form as a basis for the organization of ecology. The above discus- 
sion shows that activities are actually most important, and accordingly 
may be used in ecological study. However, since structure and activity 
(function) are always correlated, we should never lose sight of the former. 

IV. Scope and Meaning of Ecology 

I. SPECIES AND ECOLOGY 

In practice, species are diagnosed in terms of structures, such as 
number and arrangement of bristles, hair, form, color, size, etc. Such 
characters are commonly called morphological. In ecology, the morpho- 
logical characters of species are of little or no significance. Still, since 
habitat preferences are commonly closely correlated with the characters 
used to separate species, some progress in ecology can be made by the 
study of the distribution and environmental relations of species, but if 
this is not carefully checked by experimentation one may constantly 
fall into error. 

2. MORES — PHYSIOLOGY THE BASIS OF ECOLOGY 

As we have already seen, ecology^ is that branch of general physiology 
which deals with the organism as a whole, with its general life processes as 

' The unorganized phases of ecology are sometimes called natural history, biology, 
ethology, or bionomics, but usually by men having little understanding of plant ecology 
or who for some reason object to the word ecology (see 35a, pp. 18-21). The term 
ecology is applied to those phases of natural history and physiology which are organ- 
ized or are organizable into a science, but does not include all the unorganizable data 



PHYSIOLOGY AND ECOLOGY 33 

distinguished from the more special physiology of organs (13, 51). With 
these limitations upon the term physiology, what may be termed 
physiological life histories (52) covers much of the field. Under this 
head fall matters of rate of metabolism, latency of eggs, time and condi- 
tion of reproduction, necessary conditions for existence, and especially 
behavior in relation to the conditions of existence. Reactions of the 
animal maintain it in its normal environment; reactions are dependent 
upon rate of metabolism (53 and citations), which may be modified by 
external conditions. Behavior reactions throughout the life cycle are a 
good index of a physiological life history. 

If we knew the physiological life histories of a majority of animals, 
most other ecological problems would be easy of solution. The chief 
difficulty in ecological work is our lack of knowledge of physiological life 
histories. With elaborate facilities these may be worked out in a 
laboratory. Ecology, however, considers physiological life histories 
primarily in nature, and for this reason the central problem of ecology 
is the mores (13) problem. This may be defined as the problem of 
physiological life histories in relation to natural environments together 
with that of the relations of organisms in communities. The latter is 
not a part of physiological life histories, the mores conception being the 
broader. An ecological classification is a classification upon a physio- 
logical basis, but since structure and physiology are inseparable, we 
must not forget the relations of structure to ecology and to ecological 
classification.^ 

V. Communities and Biota 

I. BASIS 

Animals select their habitats probably by trial and error. The simple 
fact of selection is, we believe, familiar to all naturalists. A given 

of natural history. There has never been any attempt to organize natural history 
and physiological data into a science under the head of ethology, biology, or bio- 
nomics, and the use of these terms will not seem justified until the materials to which 
they have been applied are organized into a science. 

' Mores (Latin singular mos), "behavior," "habits," "customs"; admissible here 
because behavior is a good index of physiological conditions and constitutes the 
dominant phenomenon of a physiological life history and of community relations. 
We have used this term just as form and forms are used in biology, in one sense to 
apply to the general ecological attributes of motile organisms; in another sense to 
animals or groups of animals possessing particular ecological attributes. When applied 
in this latter sense to single animals or a single group of animals the plural is used in 
a singular construction. This seems preferable to using the singular form mos which 
has a different meaning and introduces a second word. The organism is viewed as a 
complex of activities and processes and mores is therefore a plural conception. 



34 ENVIRONMENTAL RELATIONS 

environmental complex is selected by a number of species. All of the 
animals of a given habitat constitute what is known as an animal 
community; all the life (plant and animal) is a biota. It follows that 
there is often a certain physiological or ecological similarity in the species 
which select the same or similar habitats. When not ecologically 
similar, animals living in the same or similar habitats are usually 
ecologically equivalent, i.e., they meet the same conditions in different ways. 
For example, in a swift stream, the small fishes known as darters maintain 
themselves against the swift current by their strong swimming powers 
and by orienting against the current (positive rheotaxis). The snails 
(Goniobasis) are able to maintain themselves because of the strength of 
their foot and positive rheotaxis. The darters and snails are ecologically 
equivalent with respect to current. 

There is a marked agreement of all the animals of this community in 
their reactions to the factors encountered in the stream. This agreement 
is due (a) to the selection of the habitat through innate (instinctive) 
behavior (40, 49, 54, 55), and (b) to the adjustment of behavior to the 
conditions through the effects of physical factors and through formation of 
habits and associations (44, 53). 

Animals of the same species show behavior differences in different 
habitats (44, chap, xxi; 55, p. 584; 53). Bohn found that the sea 
anemones living near the surface of the sea, where the wave and tide 
action are strongest, showed more marked rhythms of behavior in relation 
to tide than those living lower down where the action of the tide and 
waves is less marked (53a, p. 156; 53 b, p. 155). These rhythms dis- 
appeared slowly when the animals were removed from the tide to the 
aquarium. Many such cases are probably to be found in the natural- 
history literature. For example, the chipmunk differs in behavior under 
different conditions (21, p. 523). Abbot (53c, p. 104) makes a similar 
statement about fish. It is apparent then that one species may have 
several mores. Different species may sometimes have identical mores; 
these cases are usually separated geographically (55, p. 604). In 
addition to these relations, the relation of ecology to species is largely a 
matter of language, names being necessary as a means of referring to 
animals. 

The physiological and behavior relations of animals in the same 
community are of much importance and are included under (a) inter- 
physiology or psychology and (6) inter-mores physiology or psychology, 
(a) Inter-physiology. — Tarde (55, citations) is the author of the idea of 
inter-psychology. — the psychology of the relations of individuals of the 



PHYSIOLOGY AND ECOLOGY 35 

same species (man). He suggests that the social psychology of man 
may be traced to the inter-psychology and physiology of the lower 
animals. If this is true, then we can be more certain that the inter- 
psychology of the higher forms has developed from the inter-physiology 
of the lower forms (55 and citations). To this should be added the 
behavior between different species, while acting or living together as 
one. In the steppes ecologically similar animals frequently act as one 
species. Mr. Roosevelt has said that one of the most interesting features 
of African wild life is a close association and companionship often seen 
between totally different species of game (3). Mr. Roosevelt shows 
the zebra and hartebeest herding together, {h) Inter-mores physiology 
(between ecologically dissimilar forms, or antagonistic forms). — The 
relations of animals of different size, habits, etc., to one another involve 
some of the most striking features of behavior. Much of the behavior 
which tends to protect animals from enemies falls under this head.' 

In all cases of modification of behavior by the physical environment 
or by relations to other animals of the community and in all cases where 
the habitat is selected, the habitat is the mold into which the organism 
fits. The study and analysis of the habitat is a necessity as soon as the 
selection of habitat and the adjustment of behavior and physiological makeup 
to the environment are shown to be general facts. Since habitats are differ- 
ent, animal communities occupying different habitats are physiologically 
different for the reasons just given. 

The relations of the animals which make up communities are 
relations of life histories. The life histories of the different species are so 
adjusted to conditions that all animals do not reach maturity and greatest 
abundance at the same time. Some species continue throughout the 
season; for example, mammals because of their long lives, and some 
species of aphids or copepods because of their great fecundity and 
peculiar physiological makeup. There is a succession of maiture or 
breeding animals with the change of season. A similar phenomenon 
is noticeable in plants. Such succession is called seasonal succession 
(47, 56). Different species of the same community come into relation 
at different seasons of the year. 

Communities are systems of correlated working parts. Changes are 
going on all the time as a sort of rhythm much like the rhythm of activity 
in our own bodies related to day and night. In addition to this, com- 
munities grow by the addition of more species, decline, and finally 

' It is at this point that ecology comes into contact with the theories of natural 
selection, adaptation, mimicry, etc. 



36 ENVIRONMENTAL RELATIONS 

disappear from the locality with changes in environment produced 
either by themselves or by physiographic or climatic changes (57, 58). 

The general growth or evolution of environmental conditions and 
the communities which belong to them, are included under succession. 
The word succession is used in three distinct senses. We speak of 
(a) geological succession, {h) seasonal succession, and (c) ecological 
succession. 

a) Geological succession is primarily a succession of species through- 
out a period or periods of geological time. It is due mainly to the 
dying-out of one set of species and the evolution of others which take 
their places, or in some cases to migration. 

h) Seasonal succession is the succession of species or stages in the life 
histories of species over a given locality, due to hereditary and environic 
differences in the life histories (time of appearance) of species living there. 

c) Ecological succession of animals is succession of mores over a given 
locality as conditions change. If species have relatively fixed mores we 
have succession of species. When mores are flexible we may have the 
same species remaining throughout, with changes in mores. It is on the 
basis of ecological succession that we arrange the data presented in chaps, 
iv to xiv and proceed with discussion. The response of the organism 
to the condition of the environment is only occasionally or partially 
dependent upon ecological succession, but this is the only notable 
phenomenon about which habitats and animal communities can be 
arranged into a natural order. 

2. CLASSIFICATION OF COMMUNITIES 

Ecological classification of animals must be based upon community 
or similarity of physiological makeup, behavior, and mode of life. Those 
natural groups of animals which possess likenesses are the communities 
which we must recognize. One community ends and another begins 
where we find a general more or less striking difference in the larger mores 
characters of the organisms concerned. These communities usually 
occupy relatively uniform environments (58a). 

a) Ecological terminology (13). — Terminology in ecology is still 
unsettled and changing. Groupings have thus far been based upon 
similarity of habitat. Habitat likenesses have in general been based 
upon general resemblances. General resemblances have not always been 
accompanied by similar physical conditions. In general there has 
been an agreement in the recognition of strata, of associations as com- 



COMMUNITIES 37 

munities based upon minor differences in habitats, and formations based 
upon larger major differences in habitats. 

We give the communities of different orders below with taxonomic 
divisions of corresponding magnitude opposite for comparison. With 
the exception of the first, these taxonomic groupings do not bear the 
slightest relation to the ecological groupings, but are added to indicate 
magnitude. 

Ecological Groups Taxonomic Groups 

{Mos) mores Form (forms) (species) 

Consocies Genus 

Stratum or story Family 

Association or society Order 

Formation Class 

Extensive formation Phylum 

(Aquatic and terrestrial) (Vertebrates and invertebrates) 

Mores, in the technical sense in which the term is used here, are 
groups of organisms in full agreement as to physiological life histories 
as shown by the details of habitat preference, time of reproduction, 
reactions to physical factors of the environment, etc. The organisms 
constituting a mores usually belong to a single species but may include 
more than one species as specificities of behavior are not significant (13). 

Consocies are groups of mores usually dominated by one or two of the 
mores concerned and in agreement as to the main features of habitat 
preference, reaction to physical factors, time of reproduction, etc. 
Example: the prairie aphid consocies. The aphids dominate a group 
of organisms which for the most part prey upon them, as, for instance, 
certain species of lacewing, lady beetles, syrphus-flies, etc. (13), 

Strata are groups of consocies occupying the recognizable vertical 
divisions of a uniform area. Strata are in agreement as to material for 
abode and general physical conditions but in less detail than the consocies 
which constitute them (13). 

For example, a forest-animal community is clearly divisible into the 
subterranean-ground stratum, field stratum (zone of the tops of the 
herbaceous vegetation), the shrub stratum (zone of the tops of the 
dominant shrubs), the lower tree stratum (zone of the shaded branches 
of the trees), and the upper tree stratum. A given animal is classified 
primarily with the stratum in which it breeds, as being most important 
to it, and secondarily with the stratum in which it feeds, etc., as in many 
cases most important to other animals. The migration of animals from 



38 ENVIRONMENTAL RELATIONS 

one stratum to another makes the division lines difficult to draw in some 
cases. Still, the recognition of strata is essential but a rigid classification 
undesirable. Consocies boring into the wood of living trees probably 
should be considered as consocies relatively independent of stratification 
phenomena (13). 

Associations are groups of strata uniform over a considerable area. 
The majority of mores, consocies, and strata are different in different 
associations. A minority of strata may be similar. The term is applied 
in particular to stages of formation development of this ranking. The 
unity of associations is dependent upon the migration of the same indi- 
vidual and the same mores from one stratum to another at different times 
of day or at different periods of their life histories. Migration is far 
more frequent from stratum to stratum than from one association to 
another (13). 

Formations are groups of physiologically similar associations. For- 
mations differ from one another in all strata, no two being closely 
similar. The number of species common to two formations is usually 
smaill (e.g., 5 per cent). Migrations of individuals from one formation 
to another are relatively rare (13). 

Extensive formations are groups of formations clearly influenced by a 
given climate in the case of land formations and by the topographic age 
of a large area and by climate in the case of aquatic formations (13, 58a). 

A sub-formation is an association or a poorly developed phase of a 
formation. The term is used in comparing communities of the ranking 
associations when viewed from the standpoint of physiological differ- 
ences but without reference to genetic history. Accordingly the same 
community is referred to as an association in the genetic sense and a 
sub-formation when the point of view is that of physiological difference 
or resemblance. 

h) Animal communities of the forest-border region. — ^The forest-border 
region is the western line of demarkation between forest and steppe (see 
prairie area of Fig. 8, p. 51). The following is a list of the chief animal 
communities of the area about the south end of Lake Michigan. It is 
not intended to be complete, but rather to illustrate the use of the terms 
with particular reference to the communities to be mentioned later on. 
The term community is used in the general sense. Association is 
applied to stages in genetic development, with sub-formation as an 
alternative as defined above. The classification here presented in outline 
is artificial and attempts to combine the historical or genetic with the 



COMMUNITIES 



39 



purely physiological points of view. Accordingly some communities are 
mentioned more than once. Others have two names. 

I. Stream Communities 

1. Intermittent stream communities 

a) Intermittent rapids consocies 

b) Intermittent pool consocies 

c) Permanent pool, or horned dace association 

2. Permanent stream communities 
a) Spring dominated stages 

i) Spring consocies 

2) Spring brook associations 

3. Creek and river communities 

a) Pelagic sub-formation 

b) Hydropsyche, or rapids formation (turbulent-water formations) 

c) Anodontoides ferussacianus, or sand or gravel-bottom formations 

d) Sandy-bottomed stream sub-formation (shifting-bottom sub- 
formations) 

e) Silt or sluggish-stream communities 
i) Sluggish-creek sub-formations 

2) Pelagic formations 

3) Hexagenia, or silt-bottom formation 

4) Planorbis bicarinatus, or vegetation formation 

II. Large Lake Communities 

1. Pelagic formations 

2. Eroding rocky-shore sub-formations (turbulent- water formations) 

3. Depositing sandy-shore sub-formations (shifting-bottom sub-forma- 
tions) 

4. Lower-shore formations 

5. Deep-water formations 

III. Lake-Pond Communities 

1. Pelagic sub-formations ' 

2. Pleurocera subulare, or terrigenous-bottom formation 

3. Vegetation formation 

a) Leptocerinae, or submerged vegetation association 

b) Neuronia, or emerging vegetation association 

4. Temporary pond formations 

IV. Prairie or Grassland Formation of the Savaima Climate 

1. Xiphidium fasciatum, or grassland association of moist ground and 
marsh vegetation in the savanna and forest climates 

2. Prairie chicken, or high-prairie association of the savanna climate 



40 ENVIRONMENTAL RELATIONS 

V. Thicket or Forest Margin Sub-Formations of the Savanna and Forest 
Climates. Physiological group in the main though the " candlehead " 
sub-formation may develop into V, 2, or VI, 7, d 

1. Wet-ground thicket sub-formations (lower strata periodically sub- 
merged) 

a) River deposit or stream-margin thicket sub-formations. Associa- 
tion in the development of flood-plain forest 

h) Marsh and pond-margin thicket sub-formations (first association 
in the development of forests in marshes) 

c) Candlehead or moist forest margin sub-formation of the savanna 
and deciduous forest climates 

2. Straussia longipennis, or high forest margin sub-formation of the 
savanna climate (a climatic sub-formation of considerable permanency, 
probably not usually a genetic type) 

VT. Forest Communities of the Deciduous Forest Climate 

1. Elm-ash series of communities 

a) Low prairie associations (see IV, i) 

b) Marsh-margin thicket associations (see V, i, ft) 

c) Elm-ash associations 

2. Tamarack or floating-bog series of commxmities 

a) Low prairie or floating-bog association (pitcher-plant consocies) 
h) Marsh-margin thicket associations (see V, i, 6) 
c) Tamarack-forest formations 

3. Flood-plain series of communities 

a) Terrigenous river-margin associations 

b) Stream-margin thicket associations (see V, 1,0) 

c) Elm and river-maple associations (not studies) 

4. Clay series of communities 

a) Cicindela purpurea limbalis, or bare clay association 

b) Sweet-clover association 

c) High forest margin associations (see V, 2) 

5. Rock series of commxmities (little studied) 

a) Bare rock consocies 

b) Thicket association (probably high forest margin, V, 2). Later 
stages not well represented near Chicago 

6. Sand series of communities 
o) Lake-margin association 

b) Cicindela lepida, or cottonwood association 

c) Cicindela lecontei, or the pine association 

d) Ant-lion or black-oak association 

7. Climatic forest formation of the deciduous forest climate 

a) Birch-maple association of the tamarack-forest series 

b) Panorpa, or oak-elm-basswood association of the flood-plain and 
marsh-forest series 



COMMUNITIES 41 

c) Hyaliodes vitripennis, or black-oak, red-oak association of the sand 
and other sterile soil series 

d) Cicindela sexguitata, or red-oak, hickory association (climax, or final 
forest association of the savanna climate) 

e) Wood-frog or beech-maple association (the climax or final associa- 
tion of the forest climate) 

The evidence for the relations of the different formations and 
associations here suggested is presented from time to time in the following 
pages, and on the basis of this, is graphically represented in Diagram 9, 
on p. 312, where both physiological and genetic relations are indicated. 



CHAPTER III 

THE ANIMAL ENVIRONMENT: ITS GENERAL NATURE AND ITS 
CHARACTER IN THE AREA OF STUDY 

I. Nature and Classification of Environments (35a, 55, 58)' 

The environment is a complex of many factors, each dependent 
upon another, or upon several others, in such a way that a change in any 
one effects changes in one or more others. The most important environ- 
mental factors are water, atmospheric moisture, light, temperature, 
pressure, oxygen, carbon dioxide, nitrogen, food, enemies, materials 
used in abodes, etc. In nature the combinations of these in proportions 
requisite for the abode of a considerable number of animals are called 
"environmental complexes" (55). It is our purpose to consider animals 
as inhabiting environmental complexes, rather than to isolate their 
responses to various single factors. The consideration of environmental 
complexes in any comprehensive way would consume much space and 
require extensive and special knowledge of many fields. Accordingly, 
we can present here only the briefest outline of some of the principles of 
classification, and the important features. 

If one is to understand the most elementary principle of the classi- 
fication of environments, he must recognize the distinction between 
local and (55, 58a) climatic environmental complexes. Local complexes 
are often referred to as secondary or minor conditions or as edaphic or 
soil conditions. The climate, and such features as types of vegetation 
covering large areas, e.g., steppe, deciduous forest, etc., are commonly 
regarded as climatic. Opposed to these, and lying within them, are the 
local conditions, such as streams, lakes, soils, exposure, etc, which are 
only indirectly dependent upon climate. The idea can be better illus- 
trated by the desert than by our own region. For example, in the 
Mohave Desert, the climatic conditions may be characterized as hot 
and arid. Within this desert are a few streams fed by mountain rain- 
fall. These streams are local conditions in themselves, and produce 
others, such as moist soil, and types of vegetation which do not belong 
to the desert. Within the area about Chicago are represented two 
geographic complexes, the savanna and the deciduous forest, and lying 

' Numbers in the text in parentheses refer to references in the Bibliography 
(pp. 325-36). 

42 



FACTORS 43 

in and among these are various local complexes. The history to follow 
applies particularly to the local complexes. The analysis into factors 
applies to both local and climatic. 

II. The Important Factors and Their Control in Nature 

Little experimentation has been conducted with a view to determin- 
ing the relative importance of different factors in the control of animals 
within an environmental complex. It is known, however, that moisture 
(evaporating power of the air), light, and materials for abode are factors 
important in the life of land animals; carbon dioxide, oxygen, materials 
for abode (including bottom), and current, in the life of aquatic animals. 
The evidence for these statements cannot be presented here, but will be 
given in appropriate places throughout the discussion which follows. 

I. THE control of FACTORS 

This is related to physiography, surface geology, and vegetation. 

a) Physiography. — In streams, current and oxygen content are 
determined very largely by physiographic conditions. Current is a 
function of volume of water and slope of stream bed. Oxygen content 
is largely determined by the rate of flow, and therefore is influenced by 
physiography. In lakes, oxygen content is determined by the depth, 
the temperature, and winds — physiographic factors are again important. 
On land, moisture and light are in a measure controlled by physiographic 
features. Slope and direction of facing profoundly affect vegetation, 
moisture, and light. 

h) Surface materials and vegetation. — Materials for abode are largely 
the surface soil or rock or the vegetation. Surface soil or rock influences 
the moisture. Both moisture and surface materials influence the kind 
and amount of vegetation. All are interdependent (35a). 

Physiographic features change with time. Erosion changes the 
gradient of streams, the width of valleys, the steepness of valley walls 
and cliffs, the ground-water level, etc. The weathering of rock is a 
process familiar to all. It is the aggregate of processes by which the 
coarse and hard or massive materials are reduced to clay and soil. This 
requires time. 

The fact that vegetation grows upon the so-called sterile, coarse, 
rough-surface materials, usually scattered or ephemeral at first, but 
increasing in denseness with each generation, is also familiar (58). 
Plants add organic matter to the soil. This organic matter holds the 
water so that moisture increases and plants may increase. With such 



44 ANIMAL ENVIRONMENT 

changes it is obvious that an area of sterile soil will support more animals 
as time goes on, than at the outset, when the conditions were such that 
only a few hardy species could live. Here again, then, time is the impor- 
tant factor in determining the change of the area, so as to be suitable 
for more species (because more species are adapted to live in the result- 
ing than in the initial conditions). The length of time which has 
elapsed since a given set of surface and physiographic conditions became 
exposed to the atmosphere is very important in governing the number, 
kind, and distribution of animals in a given area. 

c) The value of physiographic form. — Physiographic features are 
classified according to their form and their mode of origin. What is the 
importance of their forms and modes of origin to the animal ecologist ? 
Has a kame or an esker or a valley train any significance so far as animals 
are concerned? So far as anyone has been able to observe, the fact 
that they possess their particular form is of no significance whatever. 
Their relations to present ground- water level, their slope, relation to the 
sun, etc., are significant. The amount of surface soil and the denseness 
of vegetation are also of very great importance, and conditions in these 
respects are usually closely correlated with the length of time that the 
structures have been exposed to the atmosphere. 

Since age is important, we turn at once to the history of an area in 
order to learn the relative age of the various features present. We have 
parted company with the physiographer and his discussion of mode of 
origin, and are interested in origins only in point of time, 

in. History of the Region about Lake Michigan (59) 

I. PHYSIOGRAPHIC HISTORY 

We will give the briefest possible account of the history of the Chicago 
area, following Leverett (59), Salisbury (57, 60), Alden (61), Atwood 
(62), Goldthwait (62, 63, 64), and Lane (65). 

The most important features of our area were shaped during and 
since the glacial epoch. To us, the only important movement of the 
ice was that of the last Wisconsin ice sheet. This came to us mainly 
from the east and north. It spread out over the great basins now 
occupied by the Great Lakes and thence pushed on to the higher rock to 
the south of them and reached its southernmost extent in Southern 
Illinois. 

In retiring from here (Fig. i) one of the positions in which the 
edge of the ice halted corresponded to the present Valparaiso Moraine. 
The crest of this moraine extends from the Fox Lake region (see map) 



FACTORS 



45 





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4 


p 


ICE SHEET 




ff'' 






ll'- 'J 


/pf^ 




^f; i/JL 


. /f 




AV 'iCv 


j,te' 






Ar 




V. A \!>-*K^jy 


> /*'' 


^'^ 


J) ^z5s- 




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>5^i:.^%s^r^ 





^■^-"^ ""^^^ 


6 




«.>-i. 


^' /^^ ^\ v^--^ 


I \^ 


J ( /fj ^ 


y" ""-^">'- 


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t 

--K- 



The History of the Chicago Region 

Fig. I. — Showing the region of the Great Lakes when the Wisconsin ice sheet 
was retreating from its maximum extent (after Atwood and Goldthwait). 

Fig. 2. — A part of the same area, showing the drainage of the ice sheet by the 
Kankakee and Huron rivers through Dowagiac Lake (from Lane after Leverett). 

Fig. 3. — Showing a later stage of the retreat of the ice sheet — the Glenwood 
stage (from Lane after Leverett). 

Fig. 4. — ^A later stage of the same — the Calumet stage of Lake Chicago (from 
Goldthwait after Leverett and Taylor). 

Fig. S.-rA still later stage — ^probably the Tolleston stage (from Lane after 
Leverett). 

Fig. 6. — ^A post-ToUeston stage (from Goldthwait and Atwood after Leverett 
and Taylor). 



46 ANIMAL ENVIRONMENT 

southward around the head of Lake Michigan, nearly parallel with the 
shore, then northward into Michigan, there turning somewhat more to 
the east (Fig. 2). Beyond the edge of the ice, early lines of drainage were 
established and temporary lakes came into existence. All of our south- 
ward flowing rivers bore the sediment-laden waters from the melting ice. 
The results of this may be seen in the gravel and sand outwash, valley 
trains, etc., along the DuPage and other rivers, the more sandy portion 
usually being farthest downstream. 

In Southwestern Michigan, these early lines of drainage were by 
the St. Joseph and the Dowagiac valleys. In the latter a small lake is 
believed to have existed (Fig. 2). These waters did not flow into the 
south end of the lake, as at present, but united and flowed down the 
present course of the Kankakee River. The Kankakee marsh area and 
the region at the mouth of the Kankakee (Morris Basin) are believed 
to have been occupied by a lake. These basins are surrounded by sand 
areas which are probably the oldest in our area of study. Dunes are 
said to be present to the south and east of "Lake Kankakee," a few being 
present on the moraine in the extreme southeast corner of our map 
(frontispiece). 

The next stage was marked by the retirement of the ice from the 
position of the Valparaiso Moraine to the present basin of Lake Michigan. 
The drainage of glacial waters down the Fox, DuPage, and Upper 
DesPlaines rivers stopped (Fig. 3). The lakes to the south and east 
probably began to disappear. Later, the St. Joseph and Dowagiac 
changed their lower courses and flowed directly into Lake Michigan, 
which found an outlet by way of the lower DesPlaines. 

Now begins the history treated in the first bulletin of the Geographic 
Society (60), and Bidleiin 7 of the Illinois Geological Survey and else- 
where (61, 62, 63, 64). The predecessor of Lake Michigan stood at a level 
55 to 60 feet above the present lake. The stage is known as the Glen- 
wood stage of Lake Chicago. Cliffs were cut, beaches of sand and gravel 
were deposited, and dunes were formed. These are our second oldest 
sand and gravel areas. Their position is shown on the map (facing p. 52). 

The water then fell to a level of 35-40 feet above the present lake. 
This is known as the Calumet stage (Fig. 4). Here again cliffs and 
beaches of sand and gravel were formed, and constitute our third in 
point of age. These beaches have not been indicated on the map 
because their distribution within the state of Michigan has not been 
studied by physiographers. In the vicinity of Waukegan they are very 
close to the Glen wood beach. 



FACTORS 47 

The lake again receded, probably to a low level, and readvanced to 
a 2o-foot level known as the Tolleston stage (Fig. 5). Here the develop- 
ment of beaches continued and the cutting of new cliffs was inaugurated. 
From these beaches, dunes were developed which are fourth in point 
of age. The position of these beaches is not indicated on the map. 
The lake is believed to have fallen after this to a level of 60 feet below 
the present level of Lake Michigan (60-62), which is known as the Cham- 
plain stage. At this time the sea came up the Gulf of St. Lawrence as 
far as Lake Ontario. Since the cliffs and beaches of this stage were 
again submerged, they are no doubt of some importance to the aquatic 
life in Lake Michigan, because they affected slope and bottom locally. 
The water rose again to a level 12 to 15 feet above the present lake, 
known as the Algonquin or post-Tolleston stage (Fig. 6), which was 
followed by a retreat to the present level. 

2. THE FORMER CLIMATE AND ANIMALS (66) 

During the ice age, the entire region about Chicago was overridden 
by the ice, and plants and animals migrated southward. There are at 
present a few animal species which inhabit glaciers and ice fields, and 
probably such were the only regular inhabitants at that time. The 
tundra and coniferous forest were crowded to the southward, and with 
them the caribou, musk ox, and other northern animals. As the ice 
retreated north of the southern end of the basin of Lake Michigan and 
the Lake Chicago stage was inaugurated, a tundra climate no doubt 
prevailed in the Valparaiso Moraine. It was probably the breeding- 
place of the present tundra species of birds; the home of the musk ox, 
the caribou, the snow grouse, and other northern animals. The ponds 
grew aquatic plants and probably supported hordes of mosquitoes (2) 
and other aquatic insects in summer. Early Lake Chicago is said to 
show no evidence of life. If we may judge from Arctic lakes at present, 
it had a summer fauna, especially of small crustaceans and probably 
some fishes. 

As the ice retreated still farther northward, the coniferous forest 
displaced the tundra, and the musk ox and caribou were presumably 
only winter visitors; the woodland caribou and the moose were probably 
regular residents. Conditions in the lake were similar to those of the 
preceding stage. By this time a relatively rich flora and fauna probably 
existed. Organic material accumulated in the soil, shade was produced, 
etc. With the further retreat of the ice, the coniferous forest continued 
for a long time, but the plants and animals became gradually more and 



48 ANIMAL ENVIRONMENT 

more like those of the southern p'ortion of the coniferous forest (67), 
and gradually gave way through processes of ecological succession to 
the species of the present day. Just preceding our period, the mastodon 
roamed over the site of Chicago. The skeleton of one of these was 
found in a marsh near Crown Point, Ind., another at Gary, 111. 

IV. Extent and Topography of the Area Considered^ 

The area which we shall consider has its center at a point 18 miles 
east of Lincoln Park. It extends 67 miles (108. i kilometers) to the east 
and to the west and 40 miles (64.4 kilometers) to the north and 40 miles 
to the south from this point. Measured from the mouth of the Chicago 
River it extends 85 miles (137 kilometers) eastward, 49 miles (79 kilo- 
meters) westward, 38 miles (6i kilometers) southward, and 42 miles 
(68 kilometers) northward. It is 80 by 134 miles (128.8 by 216 kilo- 
meters) and contains over 10,700 sq. miles (27,820 sq. kilometers). 

The range of altitude in the Chicago area is not great. The lowest 
part of the bottom of the lake included in our map is about 80 feet above 
sea-level. The highest point on the Valparaiso Moraine is 900 feet 
above sea-level, which gives a range of altitude of 820 feet. The surface 
of the lake is 581 feet above sea-level. The plain of Lake Chicago is 

' See frontispiece map. The term "Chicago Area" has been applied to regions 
varying in extent and direction, according to the points of view and interests of 
various authors. Chicago biologists have as yet written but little concerning the 
ecology of areas to the east of Millers, Ind. It becomes necessary to go farther from 
Chicago every year. The areas in Michigan and Northern Indiana offer the only 
substitute for those nearer to Chicago which are being so rapidly destroyed. 

The following maps covering the area have been published: 

1. Lake Michigan 

a) U.S. Hydrographic Ofl&ce, Maps Nos. 1467-75. * 

b) U.S. Lake Survey Maps, Custom House Bldg., Detroit, Mich. 

2. Land 

a) Cotmty surveyors often publish maps covering particular counties, e.g., 
LaPorte Co., Ind. 

b) Illinois Internal Improvement Committee, The Water-Way Report, Springfield, 
1909. 

c) Topographic sheets of the U.S. Geological Survey (prepared for much of the 
region covered by our map). 

d) The U.S. Land Office has maps of the original land surveys which are said to 
give roughly the distribution of prairies, forests, and marshes. 

e) Rand McNaUy & Co. pubhsh maps of all local counties. 
/) Brown & Windes' (Chicago) map of the Fox Lake Region. 

g) Davis, "Peat" (map of marshes), Ann. Rept. Mich. Geol. Surv., 1906. 



AREA OF STUDY 



49 



chiefly between 581 and 600 feet, and presents very little relief. The 
lowest point of land on our map is in the valley of the Illinois River 
below the entrance of the Kankakee, This is 480 feet above tide, or 
loi feet below the level of Lake Michigan. In passing from the lowest 
point in the lake shown on our map to the vicinity of Lake Zurich, which 
is the location of one of the high points on the moraine, one would 
travel 64 miles and make an ascent of only 12 feet per mile on the 
average. Indeed, if Lake Michigan were to become dry and its bottom 
a prairie, it would appear an undulating plain. 



V. Climate and Vegetation of the Area 

I. meteorological conditions affecting animals (68) 

The table (I) illustrates the fact that there are some notable differ- 
ences between the different parts of our area. Extreme points would 

TABLE I 





Temperature 


Mean Rainfall 


Sunshine 


Ratio of 
Rainfall to 
Evaporation 


Station 


April to September 


Year 


April 
to Sep- 
tember 


Year 


April 
to Sep- 
tember 


Year 


July, 

1887, to 
July, 
1888 






Mean 


Mean of 
Maxima 


Mean of 
Minima 


Mean 




Chicago . . . 
South Bend 


62.6 
65.3 


70.0 
76.3 


55.6 
54-3 


48 
49 


193 
18.3 


33-4 
34-5 


1695 
hrs. 


2616 
hrs. 


95% 

105% 





show greater differences. The evaporating power of the air is probably 
one of the best indices of conditions which affect animals. The ratio of 
rainfall to evaporation is the only expression of the evaporating power 
of the air which has been mapped. Fig. 7 shows this phenomenon in 
Central North America, with our area indicated. 

2. vegetation (69, 70) ■ 

Those features of the vegetation which are called climatic must be 
discussed first. The two main climatic divisions of vegetation represented 
in the Chicago area are savanna including the prairie vegetation, and 
deciduous forest. The prairie, or savanna, as distinguished from steppe, 
is a strip of country (the forest-border area) a few hundred miles wide, 
from Athabaska to Texas, where trees, chiefly oak, hickory, basswood, 



50 



ANIMAL ENVIRONMENT 



and elm, occur in groves and along streams. It has the general form of a 
bow, with its central and most eastern point at Chicago (Fig. 8) . To the 
east of Valparaiso, Ind., the forest is chiefly beech and maple (see 
frontispiece). The types are believed to stand in close relation to 
climate, especially to ratio of rainfall to evaporation (Fig. 7).' 

The vegetation of local conditions, as indicated on p. 42, is different 
from that of the region as a whole and we are concerned in part with 




Fig. 7. — Map showing ratio of rainfall to evaporation in percentages, with area 
of special study inclosed in rectangle (after Transeau). Compare with Sargent's 
map of the "Forests of North America" (loth Census Report and, Fig. 8 below). 

the relations of the animal communities of local conditions to animal 
communities of the climatic vegetation. 

VI. Localities of Study 

In beginning the investigation of any biological subject from the 
point of view of general principles, the most important step is the selec- 
tion of the material (animals to be studied). In ecological work we 

' A glance at the map shows us that our area of study is in the center of the 
Forest-Border Region. 



LOCALITIES STUDIED 



51 



have not only this, but we must make a still more important choice, 
namely, that of the locality of study. To make this selection one must 
possess a good knowledge of animal environments, such as we have 
touched upon in the preceding pages. 



BASIS OF SELECTION AND SUBDIVISION 



Such knowledge can be acquired from texts of physiography and 
plant ecology, and from special works on the area at hand. The basis 




PtMtltV 



Fig. 8. — ^Map showihg the location of the plains, savanna (prairie), and forest 
regions of North America, with area of special study inclosed in rectangle (from 
Transeau after Sargent). 



of selection is either that of age or of present conditions, or both. The 
points selected for study are called stations. Stations are subdivided 
on the basis of plant and animal habitats into substations. The sub- 
stations may represent either formations or divisions of formations. 
For example, a station Uke Wolf Lake may be divided into sandy 
shore substation, vegetation of open- water substation, and embayment 
substation. 

2. ENUMERATION OF STATIONS — GUIDE 

In the study at hand we have made use of a large number of stations 
which are enumerated below and are referred to in the text. The list 



52 ANIMAL ENVIRONMENT 

of stations and accompanying remarks with the Guide Map may serve 
as a guide to the region about Chicago for iield students. 

List of Stations with Direction and Distance by Rail from the 
Mouth of the Chicago River, and Transportation 

A. Aquatic Communities 

I. Large Lake Communities (chap. v). 

Station i. The open water, piers at Jackson Park, 6 miles south. 

Station la. The eroding shore, Jackson Park, introduced rocks. 

Station 2. The eroding shore, Glencoe, 111., C. & N.W. R.R., 20 miles 
north. 

Station 3. The depositing shore, Buffington, Ind., L.S. & M.S. R.R., 
and P. R.R., 22 miles southeast. Pine, L.S. & M.S. R.R., 
24 miles southeast. Boats and launch from fishermen. 

II. Stream Communities (chap. vi). 

Station 4. Youngest ravines, Glencoe, 111., C. & N.W. R.R., 20 miles 

north. 
Station 5. Youngest brooks, Glencoe, 111., C. & N.W. R.R., 20 miles 

north. 
Station 6. County Line Creek, Glencoe, 111., 21 miles north. 
Station 7. Pettibone Creek, North Chicago, 111., C. & N.W. R.R., 

34 miles north. 
Station 8. Bull Creek, Beach, III, C. & N.W. R.R., 41 miles north. 
Station 9. Dead River, Beach, 111., 41 miles north. 
Station 10. Spring-fed streams and springs, Cary, 111., C. & N.W. R.R., 

40 miles northwest. 
Station 11. Spring-fed streams and springs, Suman, Ind., B. & O. R.R., 

52 miles southeast. 
Station 12. Rock ravine stream, the Sag, JoKet Electric, 22 miles 

southwest. 
Station 13. Intermittent headwaters, Butterfield Creek, Matteson, 111., 

I.e. R.R., 28 miles south. 
Station 14. Small swift permanent stream, Butterfield Creek, Floss- 
moor, I.e. R.R., 24 miles south. 
Station 15. Larger swift stream and effect of rock outcrop, Thornton, 

III., C. &. E.I. R.R., 23 miles south. 
Station 16. Permanent headwaters and pre-erosion stream. Hickory 

Creek, Alpine to Marley, Wabash R.R., 28 to 31 miles 

southwest. 
Station 17. Permanent swift stream. Hickory Creek, Marley to New 

Lenox, Marley (Wabash R.R. only). New Lenox, C.R.I. 

& P. R.R. or Wabash R.R., 31 to 34 miles southwest. 



LOCALITIES STUDIED 



53 



Station i8. Sluggish small stream, North Branch of the Chicago River, 

Schermerville, CM. & St.P. R.R., 21 miles northwest. 
Station 19. Moderately swift, medium-sized stream. North Branch of 

the Chicago River, Edgebrook, CM. & St.P. R.R., 12 

miles northwest. 
Station 20. Fine gravel bottom, DuPage River, Winfield, C & N.W. 

R.R., 28 miles west. 
Station 21. Gravel bottom, DesPlaines River, Wheeling, 111., W.C R.R., 

33 miles northwest. 
Station 22. Sandy bottomed streams, headwaters of the Calumet, Otis, 

Ind., L.S. & M.S. R.R., 50 miles southeast. 
Station 23. Larger sandy stream, Little Calumet, Chesterton, Ind., 

L.S. & M.S. R.R., 42 miles southeast. 
Station 23a. Deep river, E. Gary, Ind., M.C R.R., 36 miles southeast. 
Station 24. Small and intermittent sandy streams. South Haven, Mich. 

(4 miles south), steamer, 80 miles northeast. 
Station 25. Small sandy stream, Deep River at Ainsworth, Ind., 

G.T. R.R., 46 miles southeast. 
Station 26. Medium sandy stream. Black River, South Haven, Mich., 

steamer, 80 miles northeast. 
Station 27. Large drowned sandy stream with marsh border. Deep 

River, Liverpool, Ind., P. R.R., 31 miles southeast; boats 

at saloon. 
Station 28. Sandy large drowned stream. Grand Calumet, Clark, Ind., 

P. R.R. (destroyed by industrial waste), 25 miles south- 
east. 
Station 29. Sluggish stream of the base-level type. Fox River, Cary, 

111.; boats near railroad bridge, C & N.W. R.R., 40 miles 

northwest. 

III. Small Lake Communities (chap. vii). 

Station 30. Wolf Lake (o) Roby, Ind., L.S. & M.S. R.R., P. R.R., 
electric railway from 63d St., and Sheffield boathouse, 15 
miles southeast; (Z>) Hegewisch, L.S. & M.S. R.R., P. R.R., 
or South Shore Electric R.R., boats from Delaware House 
(not practicable at low water). 
Station 300. Small lake. Lake George, Ind. Electric railway from Ham- 
mond or to Hammond from 63d St., or from Robertsdale, 
L.S. & M.S. R.R., P. R.R., 18 miles southeast; boats near 
south end of lake. For information regarding Indiana 
lakes, boats, etc., see Report of the Indiana Fish and Game 
Commission for 1907. 
Station 31. Fox and Pistakee lakes, Fox Lake, 111., CM. & St.P. R.R., 
50 miles northwest ; boats at all hotels. 



54 



ANIMAL ENVIRONMENT 



IV. Pond Communities (chap. viii). 

Station 32. Young ponds, Pond i, Buffington, Ind., L.S. & M.S. R.R. 

or P. R.R., 22 miles southeast (i miles east from station). 
Station 33. Middle-aged pond, Pond 5, Pine, Ind., L.S. & M.S. R.R., 

24 miles southeast (pond at rear of station). 
Station 34. Middle-aged pond, Pond 7, Pine, Ind., L.S. & M.S. R.R., 

24 miles southeast (pond to the right in front of station). 
Station 35. Mature pond, Pond 14, Clark Junction, Ind., P. R.R., 

23 miles southeast (the fourth pond south of bridge over 
P. R.R. tracks). 

Station 36. Late mature pond. Pond 30, Clark, Ind., P. R.R., 25 miles 

southeast (pond parallel with main street and east of school) 
Station 37. Senescent pond. Pond 52, Cavanaugh, Ind., South Shore 

Electric R.R., 27 miles southeast. 
Station 38. Prairie ponds, Roby, Ind., 26 miles southeast, east side of 

Wolf Lake, between second and third icehouses. 
Station 39. Morainic pond or small lake, Butler's Lake, Libertjrville, 111., 

CM. & St.P. R.R., 36 miles northwest. 

B. Temporary Pond and Swamp Communities. 

AQUATIC PHASES (CHAPS. VIU AND x) 

Station 40. Young artificial temporary ponds. Pine, Ind., L.S. & M.S. 

R.R., 24 miles southeast (ponds i mile northwest of station). 

Station 41. Middle-aged temporary ponds, Pine, Ind., L.S. & M.S. R.R., 

24 miles southeast (ponds i mile northeast of station). 
Station 42. Prairie temporary ponds, south of Jackson Park, I.C. R.R., 

South Chicago Branch to Bryn Mawr, 10 miles south. 
Station 43. Prairie temporary ponds, 8ist St. and Stony Island Ave., 

electric railway from 63d St. and Jackson Park Ave., south. 
Station 44. Temporary pond of prairie type, but being captured by 

shrubs. Pond 90 or 93, Ivanhoe Station, L.S. & M.S. R.R., 

to Gibson, Ind., and G. & I. R.R. to Ivanhoe (i mile 

south of Ivanhoe), 36 miles southeast. 

C. Marsh, Forest Margin, and Prairie Communities 

Station 45. Low forest margin (see Station 30). 

Station 46. Intermediate forest margin, Beverly Hills, C.R.I. & P. R.R., 

12 miles southwest. 
Station 47. High prairie, Chicago Lawn, 63d St. electric railway, 

1 1 miles southwest. 
Station 48. High prairie (some low prairie). Riverside, 111., C.B. & Q. 

R.R. or LaGrange electric railway, 1 2 miles west. 
Station 49. Temporary forest pond of early stage, Pond 93, near 

Station 44. 



LOCALITIES STUDIED 



55 



Station 50. Strictly temporary forest pond, Pond 92, near Station 44. 

Station 51. Spring-fed marsh, Gary, 111., C. & N.W. R.R., 40 miles 
northwest. 

Station 52. Swamp forest, elm, and ash. Wolf Lake, Roby, Ind., south- 
east (same as Station 30). 

Station 53. Swamp forest, wood west of Dempster St., Evanston, 111., 
C. & N.W. R.R., elevated, or surface cars, 12 miles north. 

Station 54. Tamarack swamp, Mineral Springs, Ind.,- South Shore 
Electric R.R, 46 miles southeast. (For other tamarack 
swamps, see map.) 

Station 540. Tamarack swamp, Pistakee, 111., 4 miles south of Fox Lake 
(see Station 31). 

■ D. Dry Forest Communities 

I. EARLY STAGES (CHAP. Xn) 

Station 55. On rock, Stony Island, L.S. & M.S. R.R., 12 miles south 
on suburban loop. Also Pullman electric car from 63d St. 
and Jackson Park Ave. 

n. ON CLAY (chap, xn) 

Station 56. Bluflf at Glencoe, 111., C. & N.W. R.R., 20 miles north. 
Station 57. On sand, moving dunes. Mineral Springs, Ind. (near Lake 

Mich, and Station 54). 
Station 58. Lower beach, cottonwood and pine. Pine, Ind. (near 

Station 40). 
Station 59. Pine and oak, Miller, Ind., near bridge over the Calumet, 

L.S. & M.S. R.R., 31 miles southeast. 
Station 60. Black oak (same as Station 59 but near village). 
Station 61. Clark, Ind., near Station 28. 
Station 62. Cavanaugh, Ind., near Station 37. 
Station 63. Black oak, white oak, red oak, near Station 44. 



E, Moist Forest Communities 

(chaps. XI AND xn) 

Station 64. White oak, red oak, hickory, upland forest, near Station 56. 
Station 65. Forest on Blue Island, Beverly Hills, C.R.I. & P. R.R., 

12 miles southwest. 
Station 66. Youngest flood-plain forest, New Lenox, 111., C.R.I. & P. 

R.R., also Wabash R.R., 35 miles southwest. 
Station 67. Early flood-plain forest, near Station 15. 
Station 67a. (Near station 710). 
Station 68. Mature flood-plain forest, near Station 48. 



S6 ANIMAL ENVIRONMENT 

Station 69. Elm, basswood, oak, hickory forest, Gaugars (near New 
. Lenox), 37 miles southwest, Joliet So. Electric R.R. from 

Joliet or New Lenox. 
Station 70. Oak, hickory, beech, maple, Suman, Ind., near Station 11. 
Station 71. Beech and maple, Otis, Ind., L.S. & M.S. R.R., 50 miles 

southeast. 
Station 71a. Beech and maple, Sawyer, Mich., P.M. R.R., 73 miles 

east (4 miles southwest). 
Station 71^. Beech, maple, and hemlock. Sawyer, Mich., P.M. R.R., 
73 miles east (i| miles northwest). 

F. Secondary Communities 

Station 72. Roadsides, Flossmoor, 111., near Station 14. 

Station 73. South Haven, Mich, (see Station 24). 

Station 74. Stream contamination, Riverdale, 111., I.C. R.R., 17 miles 

south. 
Station 75. Pasturing of forests, Beatrice, Ind., C.C. & L. R.R., 45 

miles southeast. 
Station 76. The growth of a modern city, Gary, Ind.; many lines of 

transportation; 27 miles southeast. 



VII. Legal Aspects of Field-Study 

The student must recognize that legally, when he leaves the public 
highway, he usually becomes a trespasser, even though he walks in a 
stream bed or along a lake margin. Public property is scarce. Still, 
since the cost of prosecution is far greater than the remuneration secured 
by it in the way of damages, etc., even the most unreasonable owners 
are not inclined to insist upon the enforcement of the laws concerning 
trespassing. It should be borne in mind, however, that owners or 
tenants are entitled to respect, and that as a usual thing they will not 
object to the student's working on their property if they be treated with 
courtesy. Damaging gates, fences, etc., should be carefully avoided, 
and gates should be left as they are found. 

Small wild animals such as insects, snails, etc., are not property, 
in the eyes of the law, and an owner would probably not be able to pre- 
vent their removal from his land except by trespass procedure. Many 
of the larger animals are considered as public property and are therefore 
protected by law. In most states nearly all birds are protected by law. 
It is usually legal to kill certain game birds in season, and certain con- 
demned birds at all times. Game mammals are protected in accordance 
with a similar plan. It is usually necessary that a license to shoot be 



LEGAL ASPECTS . 57 

obtained before shooting of any sort be carried on. This would apply 
even to the shooting of snakes, lizards, and such animals, as well as 
game. 

Fishes, turtles, and fresh-water mussels are protected in Illinois, 
as are fishes in nearly all states. The use of seines and nets of all sorts, 
including hand dip-nets, dynamite, and all other devices for securing 
fishes, is usually forbidden. The hook and line is the only exception 
in some states. Forbidden equipment is nearly always confiscatable, 
and the fines for illegal fishing are usually very heavy. 

In some states it is possible to obtain licenses or permits to take 
birds, birds' eggs, and sometimes fishes for scientific purposes. For 
specific information one should consult the state fish and game warden. 



/ 



CHAPTER IV 

CONDITIONS OF EXISTENCE OF AQUATIC ANIMALS 
I. Introduction: Comparison of Land and Aquatic Animals 

The conditions of existence of aquatic plants and animals are very 
different from those of land plants and animals. Some of the most 
important differences are as follows: 

a) Water, the surrounding medium, is about 768 times as heavy 
as atmospheric air at the sea-level. 

b) The necessary gases are in solution in the water and their diffusion 
is much less rapid than in the atmosphere. 

c) The necessary inorganic salts are in solution in the surrounding 
medium. 

d) The necessary organic food substances for plants and some of the 
carbon compounds necessary for animals are in solution in the water and 
are taken directly by the plants and animals (47). 

e) Vegetation rooted to the bottom is important in most bodies of 
water. In large lakes like Lake Michigan, however, there are very few 
attached or rooted plants, and therefore nothing comparable to the 
vegetation of the land, or to the plant-eating animals which live on it, 
is to be found. Most of the plants float freely in the water. Such 
plants are present also, however, where rooted vegetation occurs. 

II. Chemical Conditions 
I. dissolved content or water 

In order to support animals and plants, water must contain certain 
minerals and gases in solution (71). Salts (carbonates, sulphates, and 
chlorides) of magnesium, calcium, and sodium and salts of potassium, 
iron, and silicon are practically always present in solution in water, and 
their presence in definite proportions is essential to the life of the animals 
(72). Water without these has been shown to kill fish (71). Dissolved 
gases in definite proportions are also necessary. 

Gases. — The chief facts regarding the occurrence of gases in nature 
and their solubility under experimental conditions are shown in Table II. 
The standard method of expressing quantity of gas in solution is in cubic 
centimeters per liter at 0° C. and 760 mm. of mercury (73). All values 
are therefore given in these terms. 

S8 



CHEMICAL CONDITIONS 59 

TABLE II 
Showing the Distribution and Solubility of Atmospheric Gases 







Gas Values in 


Cubic Centimeters per Liter 








AT o" C 


AND 760 MM. MERCtmY 






Composition 








Kind of Water 










Having Gas 


Gas 


OF Air in 


At Temperature 


20° C. 760 mm. 


Maximum 


Content Given 




Percentages 






Amounts Found 
in Natural Fish 


IN Preceding 








Column 






Water Absorbs 


Water Absorbs 


Waters, Springs 








from Air 


Pure Gas 


Excepted 




Nitrogen, 












argon, etc. . 


79.02 


12.32 C.C. 


15.00 C.C. 


19.00 C.C. 


Lakes (74, 
P- 152) 


Oxygen 


20.95 


6.28 C.C. 


28.38 C.C. 


24.00 C.C. 


Streams, 
lakes, win- 
ter, with 
green 
algae 


Carbon 












dioxide .... 


0.03 


0.27 C.C. 


901. 00 C.C. 


30.00 C.C. 


Ponds 


Ammonia 


Small traces 




Very large 


14.00 C.C. 


Sewage con- 




locally 




quantities 




taminated 


Methane 


Small traces 
locally 




34.00 C.C. 


10.00 C.C. 


Bottom of 
lake in 
September 
(74,P-ioi) 



Nitrogen has little effect upon animals except when present in excess. 
Under these conditions in the laboratory, bubbles of the gas accumulate 
in the tissues and blood-vessels of fishes and cause death. It is not 
certain that such conditions exist in nature (Fig. 9). 

Oxygen is usually necessary to the life of animals. Most animals 
that have been studied select water with a rather high oxygen content 
instead of water with little or no oxygen. The resistance of animals to 
lack of oxygen varies in different groups. It has been found that water 
with about 6 c.c. of oxygen and 14 c.c. of nitrogen per liter is suitable 
for brook trout. Mackinaw trout have been taken in water containing 
but I c.c. of oxygen per liter (6). 

In general, carbon dioxide is a narcotic in its action upon animals. 
In small quantities it is a stimulant, especially to respiratory action. 
In large quantities it produces anesthesia and death. Several workers 
have shown that carbon dioxide is very toxic to fishes. Most aquatic 
animals that have been studied turn back when they encounter water 
containing large amounts of the gas. This turning away from carbon 
dioxide is much more decided than it is in the case of corresponding 
differences (24 c.c. per liter) in oxygen content. Fishes, for example, 



6o 



AQUATIC CONDITIONS 



turn away when they encounter as small an increase as 5 c.c. per liter 
of carbon dioxide. Since a large amount of dissolved carbon dioxide 
is commonly accompanied by a low oxygen content as well as other 
important factors, the carbon dioxide content of water (strongly alkaline 
waters excepted) is probably the best single index of the suitability of 
the water for fishes. 

Fishes do not turn away from ammonia. Ammonia is rarely present 
in any great amount in nature. The effect of dissolved methane is 

unknown. Oxygen and nitrogen go into solu- 
tion from the atmosphere and oxygen is also 
^%^ produced by green plants. The other gases 

'^ ^ are produced chiefly by organisms as excretory 

and decomposition products. 

III. Physical Conditions 

I. CIRCULATION 

The distribution of dissolved salts and 
gases is dependent upon the circulation of the 
water, as their diffusion is too slow to keep 
them evenly distributed. The circulation of 
water in streams is probably such as to keep 
all dissolved gases and salts about equally 
distributed. The water of streams has been 
found to be supersaturated with oxygen (74). 
Oxygen is taken up by the water near the 
surface. Nitrogen and carbon dioxide are 
produced especially near the bottom, and if 
the water did not circulate they would be too 
abundant in some places and deficient in 
others for animals to live. 

In lakes, during strong winds (74), there is 
a piling-up of water on the leeward side and a 
lowering of the level on the windward side. This is usually com- 
pensated for by a downward flow of the waters along the bottom, 
as shown in Fig. 10. Small lakes with little exposure to the wind 
and with considerable depth frequently develop a summer circulation, 
such as is shown in Fig. 11. Such lakes are without oxygen in the 
deeper water in summer (74), and will not support the fishes which are 
known to inhabit the deeper water of Lake Michigan; hence we con- 
clude that Lake Michigan must have a deep circulation at all times. 




Fig. 9. — ^A marine fish 
affected with gas-bubble 
disease causing protrusion 
of the eyes, due to excess 
of dissolved nitrogen in 
aquarium water (after Gor- 
ham). 



CIRCULATION AND TEMPERATURE 



6l 



We have been able to find no record of the amount of lowering of 
the waters of Lake Michigan at a given point, by the wind, nor any 
discussion of the relations of the surface currents to the effects of winds 
and the vertical circulation. The waves of large lakes rise to consider- 
able heights, as is familiar to all. They are of much importance in 
keeping a large amount of gas in solution in the lake waters. 

The current in streams differs from that in lakes in that it is for the 
most part in one definite direction, while the lake currents often alternate. 
There are backward flows and eddies at various points in streams, in 
front of and behind every object encountered in the current (57, p. 124). 
On the basis of the current, streams are classified as intermittent, swift, 





Fig. 10. — Showing the circulation of the water in a lake of equal temperature. 
W represents the direction of the wind (after Birge). 

Fig. II. — ^The circulation of the waters of a lake of unequal temperature (after 
Birge). 

moderately swift, sluggish, and stagnant or ponded. The current 
within the same stream differs at different times, and in different places. 
As we pass across a stream we find the current swiftest near the surface 
in the middle, and least swift at the bottom near the sides. 

2. TEMPERATURE 

Temperature has always been regarded as of great importance in 
the direct control of the distribution of life in water. The tendency of 
modern investigation is to show that its influence is of great indirect 
importance, and the belief in its direct importance is correspondingly 
weakened. 

The temperature in a stream is probably about the same at the 
various points in any cross-section. The extent to which daily, seasonal, 
and weather fluctuations in atmospheric temperature affect a lake is 



62 



AQUATIC CONDITIONS 



determined by the depth. Small lakes with incomplete circulation in 
summer are cold at the bottom, being heated at the surface only (Fig. ii). 
Lake Michigan is a deep lake and none of these fluctuations is felt 
throughout (see Table III below and Table IX, p. 74). In summer the 
water of the surface is warmed, but if the vertical circulation is what 
we suppose it to be, all the heat in the waters flowing downward at the 
leeward side (Fig. 10) must be absorbed above no meters. Table III 
shows the temperatures recorded by Ward (75); these were evidently 
taken at the bottom and do not therefore represent the temperatures 
at the same level in the open water, especially those records made in 
the shallower situations where the sun's rays can reach the bottom 
essentially undiminished in intensity. 

TABLE III 
Temperature of Lake MicmcAN 





Hour P.M. 




Tempera- 


Tempera- 


Temperature at 




Date 


Unless 


Sky 


ture of 


ture at 


Depth in 


Depth 




Stated 




Air 


Surface 


Next Column 


















Meters 


Feet 


Aug. 16 


4:05 


Clear 


16. 7° C. 


18.3° c. 


18.3° c. 


64.9° F. 


5-66 


18.6 


Aug. 18 


9 : 00 A.M. 


Cloudy 


18.9° C. 


17. 2° C. 


16. 7° C. 


62.0° F. 


11.32 


37-1 


Aug. 18 


12:25 


Clear- 
ing 


16. 7° c. 


17. 5° C. 


7.2°C. 


44.9° F. 


22.63 


74.1 


Aug. 16 


5:10 


Clear 


16. 7° c. 


i8.3°C. 


7.5°C. 


45-5° F. 


32.06 


105.2 


Aug. 25 


3:25 




20.0° C. 


19.4° c. 


7.2°C. 


44-9° F. 


43 38 


142.3 


Aug. 16 


12:05 


Clear 


15.6° c. 


18.3° C. 


5.2°C. 


41.3° F. 


55-93 


183.5 


Aug. II 


10:30 A.M. 


Hazy 




18.9° C. 


5.i°C. 


41 . 1° F. 


108.22 


355 


Aug. 16 


1:50 


Clear 


16. 7° C. 


18.3° C. 


4.2°C. 


39.5° F. 


112.00 


367. S 


Aug. 18 


4:30 


Scat- 
tered 
clouds 


18.9° C. 


18.3° C. 


4.2°C. 


39.5° F. 


132.66 


436.0 



3. LIGHT (76) 

Light is an important factor in controlling the distribution and 
activities of animals. The depth to which light penetrates water is 
therefore of importance. Forel found that in Lake Geneva, Switzer- 
land, during the period when the water was clearest, light diminished 
gradually from 25 to 65 meters, and then decreased rapidly to 115 meters 
where there was not suflScient light to affect the photographic plate. 
No doubt future investigation with more accurate means of measuring 
light will show that very faint light penetrates much farther. The 
depth of light penetration in fresh water is usually determined by the 
amount of sediment in the water. Forel found that in Lake Geneva 
the depth of light penetration decreased with the melting of the mountain 



LIGHT AND PRESSURE 



63 



snows and the beginning of the rainy season. The drainage area of Lake 
Michigan is very small and has little relief, and the amount of sediment 
carried in is small at all times. The depth of light penetration is there- 
fore not so much influenced by these factors as in Lake Geneva. Wave- 
action is also important in stirring the bottom materials near shore. 
We would expect the light penetration in Lake Michigan to be least 
during the rainy and windy seasons, and greatest in calm, dry weather — 
late summer and autumn,^ All of the surrounding physiographic con- 
ditions are factors controlling light. Table IV shows the seasonal 
distribution of rainfall and light penetration in Lake Geneva, and the 
seasonal distribution of winds and rainfall at Chicago. 

TABLE IV 

Showing Depth of Light Penetration in Lake Geneva and Conditions Affect- 
ing THE Same in Both Lake Geneva, after Forel (76, Vol. II, 
p. 439), and Lake Michigan 
In the eighth column the results are given in seconds, in terms of the effect on the 
photographic plate, of equivalent exposures to the sun. 





Lake Michigan 


Lake Geneva, Switzerland (after Forel) 




Rainfall 


Velocity of Wind 
at Noon 


Rainfall and Light 


Light and Depth 


Month 


Inches 


Centi- 
meters 


Miles per 
Hour 


Meters 

per 
Second 


Prec. in 
Cm. 


Li^ht 
Limit at 
Depth in 

Meters 


Intensity 
of Light 
(March) 
at Depth 
in Next 
Column 


Depth in 
Meters 


January 

Febrtiary. . . . 

March 

April 

May 

June 

July 

August 

September, . . 

October 

November.. . 
December. . . 


2.0 
2-3 

2-5 

2.7 
35 
Z7 
3-6 
2.8 
30 
2.6 
2.6 
2.1 


51 

5-2 

6.4 

6.9 

8.9 ■ 

9-4 

9.2 

7.2 

7-7 
6.6 
6.6 
5-3 


17.8 
20.0 
20.4 
19.4 
18.3 
14.4 
14.6 
13-4 
16.7 
17.6 
19.0 
19.9 


8 
9 
9 
8 
8 
6 
6 
6 
7 
7 
8 
8 




I 

7 
2 

5 
6 

5 
9 
5 
9 


4.87 
365 
4.72 
5-68 
7.91 

7-59 
7.08 
8.04 
9.42 
10.10 
7.4 
5" 


no 

75 

45 

50 

"85 


500 sec. 
500 sec. 
500 sec. 
400 sec. 
360 sec. 
120 sec. 

60 sec. 

25 sec. 

10 sec. 
2 sec. 
sec. 


0.0 
19.6 
25.2 
45-5 
55-5 
65.6 
75-6 
85.7 
95-8 
105.4 
115.6 



4. PRESSURE (76) 

Pressure in water increases with depth. The results given by Forel 
are shown in Table V. 

'The Lake Michigan Water Commission has reported greatest turbidity in 
January, February, March, and April. 



64 



AQUATIC CONDITIONS 
TABLE V (76) 



Pressure in 
Atmospheres 


I 


2 


3 


s 


8 


10 


20 


Depth in meters . 


10.328 


20.6 


30-9 


Si-S 


82.4 


103.27 


206 . 49 



It will be noted that there is a little more than one atmosphere 
increase in pressure for each 10 meters (33 feet) in depth because water 
is very slightly compressible. According to this, animals in the deepest 
parts of Lake Michigan are living under a pressure of about 375 pounds 
to the square inch. 

5. BOTTOM 

The character of materials and topography of the bottom are very 
important to animals living on the bottom, but it has its effect also on 
free swimming animals as a determining factor in the amount of sedi- 
ment. 

The kind of bottom is important because many animals are 
dependent upon solid objects for attachment and are absent from 
bottoms made up of fine materials. Others must burrow into mud 
or creep on sand and gravel. This will be discussed later in special 
cases, particularly in streams. 

Topography of the bottom in shallow water is important in lakes 
locally in affecting wave-action and currents, and through these, bottom 
vegetation and temperature. Ward (75) noted such effects but did 
not carry the work far enough to solve any of the problems involved, 
which are usually local. In lakes, bottom materials are most important 
in shallow water, because of their effect in connection with wave-action, 
the amount of sediment in suspension, and the stability of the bottom. 
The bottom materials of lakes vary greatly locally. Taking Lake 
Michigan as an example, if we were to see the region about Chicago 
denuded of all vegetation, we would be able to appreciate the fact that 
there are bowlder deposits, gravel deposits, sand, clay, and bare rock. 
Evidently the ice sheet left the same kind of bottom materials strewn 
with the same irregularity in the bottom of the lake as on the land. 
Apparently wave-action has not affected them below 25 meters (85 feet). 
The waves of Lake Michigan are believed not to move sand below 
9 meters (30 feet). It is thought that, during the Champlain stage, the 
lake stood at a level 60 feet below its present level. Along the north 
shore there is a cliff at this level with sand deposits lying on the side 
toward the deeper water. Inside of this is an area of clay and then, next 



VEGETATION AND FOOD SUBSTANCES 65 

to the present shore, sand and gravel again. It is seen that this lower 
level of the lake influenced both the topography and bottom material 
locally, both of which probably have an influence on the occurrence of 
certain animals. 

6. VEGETATION 

The amount and kind of rooted vegetation is very important to 
animals. Of all the aquatic situations with which we have to deal 
Lake Michigan has fewest attached plants, and these are all algae. 
Cladophora, Chara, and filamentous algae are the most important. 
These do not appear to have been recorded below about 25 meters; 
some of them require solid bodies for attachment, and are probably most 
abundant on the rock outcrops of shallow water. 

The vegetation of the younger streams consists largely of holdfast 
algae like those along the rock shores of the lake. These are of impor- 
tance to animals. The more sluggish streams have rooted aquatic 
vegetation. 

The vegetation is used as breeding-places. Eggs are stuck into plant 
tissues by the predaceous diving beetles (Dytiscidae) and by the water 
scorpions (Ranatra). Eggs are attached to plants by the electric-light 
bugs (Belostomidae) , back-swimmers, May-flies, caddis-flies, water 
scavengers (Hydrophilidae), long-horned leaf beetles (Donacia), snails, 
and many fish {Umbra, and probably Ahramis). Young animals are 
often dependent upon plants for shelter, to escape from enemies, etc. 
Many animals must use plants as a means of reaching the surface for 
oxygen. The most important of these are the Dytiscidae (adults and lar- 
vae), the Hydrophilidae (adults and larvae), the back-swimmers, Zaitha, 
Belostoma, Donacia, snails, Ranatra, and Haliplidae. Some, for example 
Zaitha and dragon-fly nymphs, lie in the vegetation and wait for their prey. 

Different kinds of vegetation have different values for animals. 
The bulrush is barren for the following reasons: (i) hardness makes it a 
bad place for eggs; (2) there are no clinging-places; (3) there is little 
shade; (4) it gives a high temperature in summer; (5) there is no great 
addition of oxygen by vegetation ; (6) it does not afford a suitable place 
for securing food. Equisetum is unfavorable for similar reasons. Elodea 
is excellent; Myriophyllum, good; water-lilies and Chara, only fair. 

IV. Elementary Food Substances (47) 

Nitrogen, in the form of nitrates, is necessary for the growth of the 
plants of a pond, lake, or stream, and an insufficient quantity is secured 
from mineral soil. Nitrogen can be taken from the air only by nitrogen- 



66 AQUATIC CONDITIONS 

fixing bacteria, such as Azotohacter, an aerobe, and Clostridium, an 
anaerobe. These bacteria occur on the outside of plants and animals, 
in the mud of the bottom, etc. Plants and animals provide carbon for 
the bacteria; bacteria provide the nitrites or nitrates for the plants. 

Ammonia, resulting from the decomposition of proteid of the dead 
bodies of plants and animals, is oxidized to nitrous acid; nitrous acid is 
oxidized to nitric acid by the bacteria {Nitrosomonas, Nitrobader, Nitro- 
coccus). This acid unites with bases to form nitrates and nitrites. 
There are accordingly two sources of nitrate and nitrite. Working 
against these are the denitrifying bacteria {Bacterium actinopelte [Baur]) 
which reduce nitrogen compounds to free nitrogen. Their work is 
influenced by temperature. Baur placed a standard quantity of nitrate 
infected with Bacterium actinopelte at several temperatures (47, p, 271) 
with results as follows : 

1. Temperature 25° C: Denitrification began 24 hours after inocu- 
lation; in 7 to II days later the solution was nitrate-free. 

2. Temperature 15° C. : Denitrification began 4 days after inoculation; 
in 27 days the solution was nitrate-free. 

3. Temperature 4-5° C: Denitrification began 20 days after inocula- 
tion; process incomplete 112 days after. 

4. Temperature 0° C: Denitrification not initiated. 

The quantity of life in water has been held by some to be in propor- 
tion to the available nitrogen. The amount of plankton in the sea is 
greatest in the polar regions in summer. It has been suggested that 
the greater retarding effect of low temperature on the denitrifiers, as 
compared with the producers of nitrates, is a cause of the greater quantity 
of life in colder waters. Atmospheric nitrogen in solution is important 
in the building of nitrogen compounds by nitrogen-fixing bacteria. 
Oxygen is necessary for the life of most organisms, though a few can 
live for considerable periods in its absence. Carbon dioxide is necessary 
for starch building by chlorophyll-containing plants and animals. 
These organisms form the principal (food) basis of all other organisms. 

Complex foodstuffs, such asproteids, are necessary for most animals. 
It is only animals which contain chlorophyll in the form of algae living 
symbiotically in their bodies, or otherwise, that can live without taking 
in proteid from the outside. Proteids are made only when light for the 
production of starch, nitrates, and several other inorganic foods are 
present. Light is then indirectly necessary to animals which can live 
in darkness. 

The smaller aquatic animals are commonly either alga-eaters or 
predatory. The larger aquatic animals are commonly predatory or 



QUANTITY 67 

scavengers. The rooted vegetation is eaten only to a small extent. 
Small floating or swimming plants and animals, called plankton (Figs. 
12-18, pp. 75, 76) are the basis of the food supply of larger animals. 
We could probably remove all the larger rooted plants and substitute 
something else of the same form and texture without greatly affecting 
the conditions of life in the water, that is, so far as the life habits of the 
animals are concerned. The aquatic plants are commonly covered with 
a coating of green algae, protozoa, and other small organisms, so that 
animals such as small snails may rasp the surface of the plants and secure 
food without eating the plant tissues themselves. Plants in water are 
of particular use to animals as clinging- and nesting-places. 

V. Quantity (47) of Life in Water 

The quantity of living matter in water, so far as it is plankton or 
floating organisms, has been much studied. The quantity is usually 
expressed in one of two ways: number of organisms per liter or cubic 
meter of water, determined by counting a part of a collection; or in 
cubic centimeters per cubic meter of water. In Lake Michigan (August) 
Ward (75) found an average of 11 . 5 c.c. per cubic meter in water from 
the surface to 2 m. ; from 2-25 m., 3 . 9 c.c. ; 25 m. to bottom, o . 4-1 . 5 c.c. 
He found that Pine Lake (a small lake) contained relatively less plankton 
than Lake Michigan, the surface stratum of Pine Lake containing more 
and the deeper strata much less than the larger lake. Lake St. Clair 
contains only one-half as much plankton as Lake Michigan. Lake 
Michigan contains only about one-tenth as much plankton as some of the 
small European lakes (Dobersdorfer See). Kofoid (77) found 71 .36 c.c. 
per cubic meter the maximum record for the Illinois River. The 
average for the year is 2.71 c.c. per cubic meter. The largest amount 
recorded by Kofoid is 684.0 c.c. per cubic meter (Turkey Lake, Ind.) . 

Small streams and lakes with large inflow and outflow have but little 
plankton. Large amount of plankton is commonly associated with 
high CO2 content, low oxygen content, and a large amount of carbonate 
in solution. 

The amount fluctuates from season to season. Kofoid (77) found 
the maximum for the Illinois River in April to June. The amount 
gradually decreases until December and January, when the minimum 
is reached. He also found evidence that the light of the moon increases 
photosynthesis and the amount of plankton. The maximum of Crustacea 
was found by Marsh (78) to fall in July, August, and September, differing 
in different years. The maximum in Lake Michigan probably is usually 



68 



AQUATIC CONDITIONS 



in late summer or early autumn. Smaller bodies of water are similar 
in this respect. 

I. LAW GOVERNING QUANTITY (47) 

Liebig's Law of Minimum, as applied to plants, is stated as follows: 
"A plant requires a certain number of foodstuffs if it is to continue to 
live and grow, and each of these food substances must be present in a 
certain proportion. If one of them is absent, the plant will die ; if one 
is present in a minimal proportion, the growth will also be minimal. 
This will be the case no matter how abundant the other foodstuffs may 
be. Thus the growth of a plant is dependent upon the amount of the 
foodstuff which is presented to it in minimal quantity" (47, p. 234). 
The amount of plankton is determined by the same law. All food sub- 
stances must be present in the correct proportions. The amount of 
plankton may be determined by one substance which is deficient in 
amount. 

2. AGE AND QUANTITY (6 and citatious) 

In bodies of water with small outlet, the quantity of plant and animal 
life probably increases with the age of the water body. This is because 
the foodstuffs are washed in by the inflowing water, and because rooted 
plants absorb food from the soil in which they grow, and when they die 
and decay these foodstuffs are added to the water. Accordingly, the 
older the pond and the longer rooted vegetation has grown, the greater 
the quantity of life. This principle is illustrated by an age-series of 
ponds at the south end of Lake Michigan to be discussed in detail later. 
The numbers used indicate relative age. Ponds i, 5, 7, 14, 30, 52, 89, 
and 95 were studied, but especially i, 5, 7, and 14 (6). Tables VI- VIII 
give a summary of the results. 

TABLE VI 

Showing Quantitative Results of Examination of Factors Related to 
Quantity of Plankton 



Pond Numbers — Age-Series 



14 



No. of 
Collection 



Total carbonates in parts per million . 

CO2, c.c. per liter* 

Oxygen, c.c. per liter* 

Bacteria per c.c 



138.800 
0.0 
6.28 
779 



160. 200 
3-4 
3-47 
2450 



160.300 

2.7 

2.78 

3550 



•Average of collections, April, May, June, July, taken over sandy bottom (pond i) or at the top 
of submerged vegetation (ponds 7 and 14). 



QUANTITY 



69 



We note that on the whole the carbonates, CO2, and bacteria are 
greater in quantity according to age. Oxygen is on the whole less. 



TABLE VII 
Showing the Number of Enlomostraca in Approximately 90 Liters of Water 



Body of Water 


September 3, 4 


April 30, 1910 


Average of 
Collections in 
Parentheses 


Relative Age 


Wolf Lake 


213 

232 

4,115 

556 

539 

2,773 

1,039 

351 

2,870 


2,900 

9,333 
19,866 
Aug. 28, 19 1 2 
104 

133 

2,600 
11,400 

2,480 


1,556 (3) 

4,781 (3) 

",991 (3) 

874 (6) 

927 (6) 

2,680 (6) 


i 


Prairie Pond I 


3 
14 . 

I 


Prairie Pond II 

Pond I 


Pond 7 


7 

14 
30 

52 

89 
95 


Pond 14 


Pond 30 


Pond 52 


Pond 89 


Pond ? 





TABLE VIII 

Showing Ratio of Number or Quantity of Different Organisms When the 

Maximum Is loo 



Rooted vegetation 
Eniomostraca . . . . 
Midge larvae .... 

Sphaeridae 

Gilled snails 

Lunged snails .... 

Amphipoda 

Crayfishes 

Insects 

Fish 



Pond Numbers — Ecological Age-Series 



20 
32 
80 
o 
20 
10 

50 

10 

40 

100 



60 

35 
80 
SO 
50 
SO 
90 
SO 
90 
87 



14& 



100 

100 
100 
100 
100 
100 
100 
100 
100 
87 



The Enlomostraca are rated on the basis of actual count of six col- 
lections. The other figures are estimates (6). 

Here we note that the number of Entomostraca was greater in the 
older ponds though some irregularities occur, dependent upon the 
amount of rainfall. In rainy seasons the increase with age appears 
almost throughout. 

As we pass from younger to older ponds we note an increase in the 
number of animals, excepting fish. These appear to decrease, probably 



70 



AQUATIC CONDITIONS 



because of the increasing unsuitability of the ponds as fish breeding- 
places. The oxygen content decreases, particularly on the bottom. 
The distribution of the fish present in these ponds, and whose breeding 
habits were known, was found to be correlated with the distribution 
of the bottom upon which they breed. This becomes less and less in 
amount as the ponds grow older. 

3. EQUILIBRIUM 

Each animal prefers certain food. The food relations of pond 
animals are shown in Diagram 3, below. For purposes of illustration 
let us suppose the existence of a community composed of the species 
named only. 




Diagram 3. — Showing food relations of aquatic animals. Arrows point from the 
orga;nisms eaten to those doing the eating. For explanation see text. 

Any marked fluctuation of conditions is sufficient to disturb the 
balance of an animal community (see chap, i, p. 18). Let us assume 
that because of some unfavorable conditions in a pond during their 
breeding period the black bass (79) decreased markedly. The pickerel, 
which devours young bass, must feed more exclusively upon insects. 
The decreased number of black bass would relieve the drain upon the 
crayfishes, which are eaten by bass, crayfishes would accordingly increase 
and prey more heavily upon the aquatic insects. This combined attack 
of pickerel and crayfishes would cause insects to decrease and the number 
of pickerel would fall away because of the decreased food supply. Mean- 
while the bullheads, which are general feeders and which devour aquatic 
insects, might feed more extensively upon moUusks because of the 



EQUILIBRIUM 



71 



decrease of the former (see chap, i, p. 15), but would probably decrease 
also because of the falUng-off of their main article of diet. We may 
thus reasonably assume that the black bass would recover its numbers 
because of the decrease of pickerel and bullheads, the enemies of its 
young. A further study of the diagrams shows that a balance between 
the numbers of the various groups of the community would soon result. 




Diagram 4. — Showing the life histories of the animals of the pond commimity 
in the form of circles. The heavy, vertical, black lines represent the animals which are 
dependent upon the most elementary food substances. A represents dead animal 
matter; B, the protozoa, rotifers, and Entomostraca, the smallest animal food. The 
black lines come into contact with different numbers of life cycles, but are indirectly 
connected with all so that any change in the position or rate of movement (meaning 
number or rate of reproduction and growth) of the rod must effect the entire com- 
munity; compare with Diagram 3. 

Diagram 5. — Showing the food relations in the brook commvmity. A repre- 
sents algae which grow upon the stones. B represents the floating animal bodies and 
other organic matter. The latter are of small importance because of their small 
nmnber and the swift current. 



Under other circumstances, such as the extinction of the black bass, the 
resulting condition would be entirely dififerent from the original one, 
but a balance between supply and demand would nevertheless finally 
be established. The community is said to have equilibrated when such a 
condition is reached; that is, a new equilibrium is established which 
may or may not he like the old. 



72 AQUATIC CONDITIONS 

The causes of fluctuations of numbers of organisms are numerous. 
Cold winters often destroy aquatic vertebrates. Large rainfall dilutes 
the plankton in streams and carries it away. Too little sunshine causes 
a poor production of the chlorophyll-bearing organisms which are the 
food basis of all the others. High temperature favors denitrification. 
From Diagram 3 and brief discussion above it will be seen that there 
are in a pond community, close interrelations traceable to certain groups 
which are closely dependent upon" the more elementary food substances. 
A representation of these relations is given in Diagrams 4 and 5. 



CHAPTER V 

ANIMAL COMMUNITIES OF LARGE LAKES (LAKE MICHIGAN) 

1. Conditions 

I. GENERAL (75) 

Lake Michigan lies between 4i°-4o' and 46''-5' N. latitude. Its total 
length is about 350 miles and its greatest width is approximately 85 miles. 
Its area is about 25,000 sq. miles. Its greatest depth is nearly 275 meters 
(900 ft.) and its average depth is approximately 122 meters (400 ft.). 

Within the area covered by our map (frontispiece) there are about 
3,200 sq. miles. The maximum depth is about 152 meters (500 ft.). 
It has been estimated that the lake contains 262,500,000,000,000 cubic 
feet of water. It becomes obvious at once that the lake constitutes one 
of the most uniform and extensive environments with which we have to 
deal. 

2. CIRCULATION . 

The level of the lake fluctuates from season to season with the 
amount of rainfall, but we have been unable to find a statement as to the 
amount of such fluctuation. Changes in atmospheric pressure over part 
of the lake cause various fluctuations in level, called seiches. In Lake 
Michigan there is a definite circulation of the surface waters. Here the 
current moves southward alon^ the west shore (57), around the head of 
the lake, and northward along the east shore. The rate of flow is 4 to 90 
miles per day. 

II. Communities of the Lake* (80, 81, 82, 83, 84) 

One of the recognizable animal communities of Lake Michigan is 
made up of the animals which live freely in the water, either swimming 
or floating. This community is called the Pelagic or Limnetic com- 
munity. Other communities are governed directly or indirectly by depth 

■ The only published account of the invertebrate fauna of the Great Lakes is 
that of Lake Superior. From this account and from incidental scattered notes found 
in various publications cited we have been able to bring together enough data to give 
an idea of the conditions and life which we may expect future investigations to show. 
The attempts to study Lake Michigan have been ill-fated. In 187 1, the Chicago 
Academy of Sciences and the United States Fish Commission co-operated in an 
attempt to study the fauna of the lake. The work on the vertebrates was published 

73 



74 



COMMUNITIES OF LARGE LAKES 



and bottom. Accordingly the conditions on the bottom at various 
depths are roughly shown in Table IX. 

TABLE IX 



Physical CoNomoNs 


Depth 




Meters 


Feet 




Limit of sand-moving waves 

Limit of daily temperature fluctua- 
tions; limit of wave action; be- 
ginning of light decrease; pressure 
about 25 atmospheres 


8 

25 
39 

54 
70 

"5 
153 
274 


26 

82 
128 

177 
230 

377 
500 
900 


Lowest record of Chcfd 


Pressure 4 atmospheres; light re- 
duced to f 


and (75) Cladophora 

Scanty filamentous algae 

(75) 

Nostoc and diatoms (75) 
No bottom plants recorded 

No plants recorded 
No plants recorded 
No plants recorded 


Seasonal temperature fluctuations 
less than 1°; light reduced to |; 
pressure sf atmospheres 

Light 5; pressure 7 atmospheres. . . 

No light; pressure 115 atmospheres; 
no change in temperature; uni- 
form conditions 


Greatest depth in the area con- 
sidered; pressure 15 atmospheres 

Greatest depth in lake; pressure 27! 
atmospheres 







I, THE LIMNETIC COMMUNITY 

(Station i ; List I) 
Chicago is famous for its good water supply. However, if one fastens 
a small sack of miller's bolting-cloth under an open water tap for an 
hour in summer and examines the contents of the sack with the naked 
eye and then with the microscope, he will be of the opinion that he has 
not been straining drinking water but stagnant ditch water. He finds 
small microscopic plants in great numbers (75), as well as large numbers 
of small animals, most of the larger ones dead. Every person drinking 
water from a lake or river drinks the small plants and animals. If 
every one of the 2,000,000 persons in Chicago drank a quart of unfiltered 

by the United States Fish Commission, and Doctor Stimpson of the Academy pub- 
lished a brief note on the invertebrate forms foxmd in the lake, but never gave more 
than a hint of the work, as the collections were all burned with the Academy's build- 
ing. Subsequently, collections were made by the State Laboratory of Natural His- 
tory, and later by the Fish Commissioners of Michigan. In the summer of 1902, the 
University of Chicago and the Academy of Sciences made a single-day excursion, 
but no report was ever published. 



LIMNETIC COMMUNITY 



IS 



city water in a day in August, all together they would be consuming 
about lo quarts of solid plant and animal substance — enough to make 
a meal for about forty people. 

One does not think of the lake as an area of luxuriant vegetation, 
teeming with animal life, but rather as a barren waste of water. How- 
ever, if one's vision for small objects were only better, he would see as 
he passes over the water in a boat, thousands of small animals and plants 
such as are shown in Figs. 12-18 together with about fifty other forms of 
protozoa, wheel animal- , 

cules, crustaceans, insects, 
and small fish. Most of 
these spend their entire 
existence freely floating or 
freely swimming. With 
the exception of the fish 
and insects they consti- 
tute the plankton which is 
the basis of the food of the 
millions of pounds of fish 
taken from Lake Michigan 
every year. 

From the standpoint 
of our economic interests, 
the limnetic formation 
is of great importance. 






Fig. 12. — A sun animalcule {Actinophrys sol 
Ehrbg.); 330 times natural size (after Leidy). 

Fig. 13. — Protozoan {Peridinium tabulatum 
Ehrbg.); 400 times natiural size (after Kent). 

Fig. 14. — A shelled protozoan (Difflugia glohu- 
losa Duj.); 130 times natural size (after Leidy). 



It deserves comment also 
because of its scientific 
interest, and the aes- 
thetic value of the vari- 
ous forms of which it is 
composed. 

a) Its composition (85, 86, 87, 88, 89). — The minutest animals of 
this formation are the protozoa. About thirteen species have been found 
to inhabit the open waters of the lake. Of these the sun animalcule 
{Actinophrys sol) (Fig. 12) and the shelled protozoan {Difflugia glohu- 
losa) (Fig. 14) are easiest to recognize. Nine of the thirteen common 
species are mixotrophic in their nutrition (i.e., contain chlorophyll and 
manufacture their own food) (Fig. 13) and share with the algae and 
diatoms the important function of furnishing food for the rotifers (wheel 
animalcules) and the crustaceans. 



76 



COMMUNITIES OF LARGE LAKES 



About a dozen species of crustaceans are common in the lake. They 
feed chiefly on the protozoa, diatoms, desmids, and possibly the rotifers 
(85). Siich crustaceans constitute almost the sole food of young fishes and 
are the first food of the young whitefishes (79). They are divided into 
copepods and Cladocera (and ostracods, rare). This division of the 
crustaceans is known as the Entomostraca. The smallest and most 




15 '8 




Representative Crustaceans and Rotifers of the Limnetic Community of 

Lake Michigan 

Fig. 15. — ^A common copepod {Cyclops biciispidalus); 25 times natural size 
(after Forbes). 

Fig. 16. — A cladoceran (Bosmina); enlarged (from Forbes after Gerstaecker) . 

Fig. 17. — ^A cladoceran (Daphne hyalina galeaia); enlarged as indicated (after 
Smith). 

Fig. 18. — A pelagic rotifer (Nolops pelagicus Jen.); i8o times natural size (after 
Jennings) . 

Fig. 19. — ^The same, side view. 



abundant of the Entomostraca of the lake is only i . i mm. in length and 
is slender and colorless. It is the slender Cyclops bicuspidatus, shown 
in Fig. 15. 

The commonest Cladocera of the lake are Bosmina (Fig. 16), Daphne 
retrocurva, and Daphne hyalina (Fig. 17). One other small species 
(Leptodora hyalina) belonging to this group is a very interesting creature. 



SHALLOW WATER COMMUNITIES 77 

"When in its native element it is almost perfectly transparent and 
consequently invisible — a true microscopic ghost" (Forbes, 89). 

The wheel animalcules are as a rule larger than the protozoa and are 
of a much higher structural organization, capable of making more 
complex movements. About thirteen species of these may be found in 
the waters of the lake in midsummer. Notops pygmaeus Calm, (see 
Figs. 18-19) is a characteristic member of the group. 

In addition to these forms there are also worms, such as round worms, 
planarians, leeches, etc, found in the limnetic formation either inciden- 
tally or habitually. 

None of the adult fishes of the lake belong strictly to the limnetic 
formation. Fishes such as the whitefish, lake herring, and lake trout 
are sometimes found in the open water, and the young of some lake 
fishes may belong there strictly (90). 

b) Characters. — Specialists in the various groups of animals might be 
able to pick out some structural characters which would distinguish 
the forms of such open-water situations from the forms living in among 
the vegetation or on the bottoms of this or smaller lakes. The only 
striking structural character is the transparent or translucent color of 
most of the forms. 

A large number, if not all, of the limnetic crustaceans are in deep 
water during the day and come to the surface at night. The behavior 
of the rotifers is somewhat different. Jennings (87) says: "During 
the day the limnetic rotifers are found in much greater numbers near 
the surface than near the bottom, reversing the condition commonly 
observed for the crustaceans. At night the distribution seems not to be 
materially changed. The immense numbers of crustaceans obscure the 
rotifers; but there was no greater number of rotifers near the bottom 
in the few to wings made at night than in the day time." 

The most striking characteristic of the limnetic formation is that it is 
independent of bottom and in its reactions is indifferent to the bottom. 
Jennings (44) states that pelagic forms have a more simple type of 
behavior than the attached and bottom forms. 

2. BOTTOM COMMUNITIES 

Forms inhabiting the bottom of lakes and also of the sea in a general 
way bear the same relation to the water that the terrestrial animals do 
to the surface of the land. Usually they do not leave it to rise to any 
considerable height above the bottom. The fishes of lakes correspond 
to the birds of the land. 



78 COMMUNITIES OF LARGE LAKES 

Other relations are, however, different. As has been stated, there 
are no truly rooted plants in the bottom of Lake Michigan. Those 
attached to the bottom are not rooted in the way that land plants are. 
The things which land plants get from the soil are supplied to the aquatic 
plants by the water itself. The same is true of the bottom animals; 
food is floating in the water in quantities and can accordingly be secured 
without effort, and some animals have the form of plants and simply 
depend upon the food which may be brought within reach by accident. 

Classification of bottom formations: Bottom formations are de- 
termined by depth (and associated phenomena) and bottom. Bottom 
is of greatest importance in shallow water (less than 8 meters). Its 
importance is inversely proportional to depth. 

Within the zone of wave-action conditions are somewhat different 
than below it. Here the kind of animals is determined by (i) strength 
of wave-action, (2) erosion and kind of material eroded, and (3) deposi- 
tion, and animal communities may be classified as those of (i) eroding 
— rocky or stony — shores, (2) depositing or sandy shores, and (3) pro- 
tected situations. 

a) Eroding rocky shore sub-formation (80, 81, 82, 83, 84) (Stations 
la, 2; Table XV). — There are a considerable number of rock outcrops in 
the bottom inside the 8-meter (26 ft.) line, between Gross Point and the 
mouth of the Calumet River at South Chicago (61). As we shall see 
later, these are of great importance to the animals of the lake. However, 
the communities of such situations are known to us only through the 
study of the very shallow water in the vicinity of Glencoe. Here, attached 
to the rocks by their silk, are caddis- worms (Hydropsyche). (Mr. W. J. 
Saunders has given me specimens of Parnidae (Psephenus) and stone-fly 
nymphs (Perla) taken from Lake Ontario at Kingston, Ontario.) All 
these ordinarily live in swift streams. Under the stones and among 
the algae attached to them are amphipods {Hyalella knickerbockeri) 
and May-fly nymphs (Ephemeridae), but so far as we have been able to 
record these are the only forms common here. The animals avoid the 
waves by creeping under stones or are attached to withstand wave- 
action. The lake trout (Fig. 20) is known to breed on the rocks off 
Lincoln Park. These rocks are then of considerable importance to the 
fish. Some species of small fish may be common here, but they have 
not been studied. 

b) Sandy depositing shore sub-formation, 0-8 meters (26 ft.), shifting 
sand bottom (Station 3; Table XII). — On the open shore inside of 1.5 
meters (5 ft.) of water we have found nothing on the bottom. From this 



SHALLOW WATER COMMUNITIES 



79 



depth to 4 meters (13 ft.) Sphaerium vermontanum, which occurs rarely 
in Hickory Creek also, and midge larvae (a red and a white species) 
appear characteristic. A number of species of small fish such as the 
blunt-nosed minnow, the straw-colored minnow, and shiners are likely 
to be found in from 4-8 meters (13-26 ft.) of water. An occasional 
Lytnnaea woodruffi, is found at this depth. 




Representative Fishes Belonging Mainly to the Transition Belt of 
Lake Michigan (25-54 m.) 

Fig. 20. — Great Lakes trout {Cristivomer namaycush) ; length 3 feet (after Jordan 
and Evermann) . 

Fig. 21. — The long-jaw whitefish {Argyrosotnus prognathus); length 15 inches; 
from the depth of 74 meters (after Smith). 



c) Communities of protected situations (Table X). — Near Chicago, 
bays and inlets are rare. Doubtless the mouths of some of the larger 
rivers before, they were modified for navigation, were of this character. 
Such places have been studied in Lake Superior (80, 83) and the Grand 
Traverse Bay region. Out of 21 species recorded here, 16 are definitely 



8o COMMUNITIES OF LARGE LAKES 

recorded below g meters and not on the open shores. All are found in 
small lakes and sluggish streams. 

d) Lower shore formation (8-25 meters) (Station 3; Tables XI, XIII, 
XV). — The belt immediately below the shore belt is characterized by 
wave-action sufl&cient to move only the finest material. Its lower limit 
is the limit of wave-action; the beginning of light diminution; the lower 
limit of daily fluctuation in temperature; and the lower limit for most 
of the species of Mollusca (75, appendix). Practically all the forms that 
have been recorded here are inhabitants of still, shallow water also. 
Notable among these are the common still-water amphipod Eucrangonyx 
gracilis, the little bivalve Sphaerium striatinum, and several species of 
Amnicola and Valvata which, together with Lymnaea woodruffi, are more 
characteristic of Lake Michigan than of shallow waters. While a large 
number of Mollusca are recorded from the lake above 25 meters only the 
Sphaeridae are found below this limit. Small annelids, midge larvae, 
and leeches are very abundant north of Gary, Ind., in 11 meters of water. 

This belt is the principal breeding-ground of the whitefish. The 
eggs are deposited on the bottom and left unguarded. It appears that 
the young fish stay in the shallow waters for a considerable time. Wher- 
ever the bottom is firm the lake trout breeds also. Nearly all the fish 
traps are set in the upper edge of this belt and in the lower boundary of 
the one above. 

e) Belt of overlapping: upper deep-water belt (25-54 meters) (Tables 
XIV, XV). — This belt is characterized as below wave-action, below 
daily fluctuations of temperature, with seasonal fluctuations not exceed- 
ing 3° C. It is intermediate between the belt above and the deep belt, 
and is the characteristic feeding-ground of the whitefish and the regular 
home of the long- jaw {Argyrosomus prognathus, Fig. 21). On the other 
hand, it is the upper limit for some of the deeper-water forms, such as the 
well-known My sis relicta a,nd Pontoporeia hoyi (Figs. 22, 23), the deep- 
water crustaceans which are the chief food of the whitefish. 

/) Deep-water formation (54 meters to bottom) (Table XV). — This 
belt is characterized by weak or no light and by seasonal changes in 
temperature less than i degree. Below 115 meters there are no light 
and no seasonal changes, and the temperature is 4° C. throughout the 
year. Off Racine in 82 meters (265 ft.) the bottom is of reddish-brown 
sandy mud (82); in 95-125 meters (311-410 ft.) dark-colored impalpable 
mud, depressions with decaying leaves (82a). In the Grand Traverse 
Bay region, Milner found decaying sawdust in 183 meters (600 ft.) (81). 
Except for unimportant variation in bottom, conditions are practically 
uniform throughout. Milner (81) states that the invertebrates are 



SUMMARY 



8i 



abundant and evenly distributed throughout the deep-water belt. The 
principal invertebrates are Pontoporeia hoyi, Mysis relicta, water-mites, 
midge larvae, and a species of Pisidium. 

The fish, however, show some noteworthy peculiarities of distribution. 
The lake trout rarely leaves this belt, except during the breeding season. 
The blackfin (Argyrosomus nigripinnis) is below 70 meters, except in 
December, when it has been recorded in 60 meters. Hoy's whitefish 




Representative Crustaceans of the Deep-Water Community of 
Lake Michigan 

Fig. 22. — 'A schizopod {Mysis relicta); enlarged as indicated (after Smith). 
Fig. 23. — ^An amphipod {Pontoporeia hoyi) (after Smith). 

{Argyrosomus hoyi) is rare, and Triglopsis thotnpsoni has not been 
recorded above 115 meters; all accordingly live under uniform condi- 
tions — no day, no night, no seasons. 

III. Summary 

The available data on the conditions and life in the lake are of such 
a nature as to justify few conclusions of weight. We find only hints 
here and there which may be useful to those who shall investigate the 
lake in the future. 

I. Bottom forms are the most abundant on the open shores which 
are rocky, and which form good substrata for the attachment of algae 
and the holdfast organs of animals. 



82 ■ COMMUNITIES OF LARGE LAKES 

2. The sand-depositing shores are without animals, at least to a depth 
of 1 . 5 meter, and life is scanty to 8 meters, on account of the shifting 
character of the bottom. 

3. Animals are abundant in protected bays; the species inhabiting 
these situations are commonly found in sluggish streams and small 
lakes, and a few of them have been recorded below 8 meters also, which 
is relatively quiet water. 

4. The animals of the upper shore belt, 0-8 meters, are found also 
in swift streams. 

5. The animals of the lower shore and upper deep-water zone are 
below effective wave-action and are those found in still waters. 

6. The animals of the deep-water zone are not found outside of deep 
lakes, and cannot be compared with any others of our Chicago area. 

7. We have, then: swift- water animals in the upper belt, still- water 
animals in the middle belt, and deep-water animals in the lowest. 

8. The fish are migratory and deserve special comment. 

DISTRIBUTION OF WHITEFISH AND DEEP-WATER FISH IN LAKE MICHIGAN (75) 

Argyrosomus artedi, the lake herring, is near the surface. 

Coregonus clupeiformis, the whitefish, lives most commonly between 21 and 

36 meters; it spawns in water between 3 and 28 meters, most commonly 

between 15 and 19 meters. It makes migrations into the 9-meter belt 

in summer, supposedly on account of bad aeration; has disappeared 

where breeding-grounds have been destroyed. 
Argyrosomus prognathus, the long-jaw, is found mainly in from 36-66 meters. 
Argyrosomus nigripinnis, the blackfin, is found in from 70-80 meters, coming 

up to 60 in December. 
Argyrosomus hoyi, Hoy's whitefish, is usually recorded below 115 meters. 
Triglopsis thompsoni is confined below 115 meters. 
Cristivomer namaycush, the lake trout, is confined below 25 meters, except 

during the breeding season. It breeds between 2 and 25 meters on rock 

or other hard bottom. 
Lota maculosa, the lawyer, appears to be distributed throughout, but no 

account is to be found regarding its movements or their causes. 

An interesting truth is illustrated by the species of whitefishes 
{Argyrosomus and Coregonus). If a group is to be successful and become 
extensive in its distribution, it must so differentiate in habits as to bring 
the different races out of competition with each other. We usually 
find that different species which are closely related have different habitats. 
Here we have these species of fish arranged one above the other. The 
separation in such cases is usually horizontal. 



ANIMALS OF LARGE LAKES 



83 



Animals Recorded from Lake Michigan* 
LIST I 

Common Entomostraca 
Copepods: Cyclops leuckarti Claus, C. bicuspidatus Claus, C. prasinus Fischer, 
Epischura lacustris Forbes, Diaptomus ashlandi Marsh, D. oregonensis Lil.; Clado- 
cerans: Daphne hyalina Ley., and D. retrocurva Forbes. 

TABLE X 

Animals occurring in protected situations (bays, harbors, etc.) in Lake Superior 
in from 0-2 meters of water, and known also to occur in Lake Michigan where habitats 
are not recorded: 



Common Name 


Scientific Name 


Literature 




Anodonta grandis Say 


(75, 83, 91) 




Anodonta marginata Say 


(75, 83, 91) 


Snail 


Atnnicola lustrica Pils 


(75, 83, 91) 


Snail 


Valvala tricarinaia Say 


(75, 83, 91) 









TABLE XI 

Animals of the lower shore belt. Those definitely recorded from 8-15 meters of 
water are marked * and **, the latter indicating that the records are original from 
II meters of water north of Gary, Ind. (Station 3); f indicates that the animals 
are recorded from protected bays in 0-2. meters of water (Lake Superior), and ^ 
that they occur in inland waters, especially ponds: 



Common Name 


Scientific Name 


Literature 


til Snail 


Lymnaea siagnalis Linn 


(75, 83, 91) 


tif Snail 


Planorbis hicarinatus Say 


(75) 83, 91) 


f ^ Snail 


Planorhis exacuius Say 


(7?, 8?, 01) 


tl[**Snail 


Amnicola limosa Say 


(91) 


t1[**Snail 


Atnnicola limosa porata Say 


(91) 


t1I**Snail 


Amnicola emarginata Kiister 


(91) 


t1[**Snail 


A mnicola lustrica Pils 


(91) 


**Snail 


Valvata bicarinata perdepressa Walk 

Valvata sincera Say 




tH Snail 


(91) 


t **Bivalve 


Pisidium idahoense Roper 


(75, 83) 


t1f**Bivalve 


Pisidium scutellatum Sterki 


(83, 91) 


tTf**Bivalve 


Pisidium compressum Prime 


(91) 


t1[* Bivalve 


Pisidium variabile Prime 


(Ti, S%, 01) 


tU* Bivalve 


Pisidium ventricosum Prime 


(7";, S'?, 01) 


t1[* Bivalve 


Pisidium punctalum Sterki 


(75, 91) 


t1f**Bivalve 


Sphaerium.striatinum Lamarck 

Calyculina transversa Say 


(80) 


t1I**Bivalve 


(91) 


1[* Midge larva 


Metriocnemis sp 


t 


H* Leech 


Glossiphonia stagnalis Linn 


(91a) 


1[**Worm 


Limnodrilus claparedianus Ratzel 









X See citation q8. 

' The numbers in parentheses in the column headed 
ences in the Bibliography at the end of the bock. 



'Literature" refer to refer- 



84 



COMMUNITIES OF LARGE LAKES 



TABLE XII 

Animals on depositing shores in from 0-8 meters of water, * indicating that 
records are original. 



Common Name 



Scientific Name 



Literature 



*Bloodworm 

*Bivalve 

*Midge larvae 

*Snail 

Long-nosed sucker. . . 

Common sucker 

Hog sucker 

Red-horse 

*Trout perch 

Minnow 

Straw-colored minnow 

*Shiner 

*Blunt-nosed minnow. 

Top minnow 

Johnny darter 

Least darter 

Lake herring 

Pumpkinseed 

Bluegill 

Mud minnow 

Eel 



Chironomid larvae 
Sphaerium vermontanum Prime (characteris- 
tic) 

Metriocnemus sp 

Lymnaea woodruffi, Baker (rarely) ... 

Catostomus caiostomus Fors 

Catostomus commersonii Lac 

Caiostomus nigricans LeS 

Moxostoma aureolum LeS 

Percopsis guliatus Ag 

Notropis hudsonius DeW. Clin 

Notropis blennius Gir 

Notropis atherinoides Raf 

Pimephales notatus Raf 

Fundulus diaphanus menona J. and C 

Boleosoma nigrum Raf 

Microperca punctulata Put 

Argyrosomus ariedi LeS 

Eupomolis gibbosus Linn 

Lepomis pallidus Mitch 

Umbra limi Kirt 

Anguilla rostrata LeS 



(81, 84) 

(81, 84) 

(81, 84) 

(81, 84) 

(81) 

(84) 

(84) 

(84) 

(84) 

(84) 

(84) 

(84) 

(75, 84) 

(81) 

(81) 

(81) 

(81, 84) 



TABLE XIII 
Animals occvirring in from 15-25 meters of water: 



Common Name 



Scientific Name 



Literature 



Snail. . . , 
Polyzoan 
Snail. . . . 
Snail. . . , 
Leech. . . 
Larvae. . 
Rotifer. . 
Rotifer. . 



Amnicola walkeri Pils. . . . 

Plumalella sp 

Pleuroceridae 

Lymnaea sp 

Clepsine sp 

Neuropteroid insects. . . . 
Rotifer elongatus Weber . . 
Dinocharis tetractis Ehrbg 



(75, 83) 
(81, 82) 
(81, 82) 
(81, 82) 
(81, 82) 
(81, 82) 
(75) 
(75) 



TABLE XIV 

Animals occurring in from 25-54 meters of water: 



Common Name 


Scientific Name 


Literature 


Bivalve 


Pisidium sp 


(82) 
(75) 
(75) 


Polyzoan 


Paludicella ehrenbergii van Ben 


Polyzoan 


Fredericella sultana Blum 







ANIMALS OF LARGE LAKES 



85 



TABLE XV 

Showing the recorded distribution of animals occurring in several of the vertical 
belts of Lake Michigan. The star indicates that the animal is present at the 
depth indicated at the head of the column in which the star occurs. B indicates 
that it breeds, and F that it feeds, at the indicated levels. The nimibers in the 
column headed "Literature" refer to the Bibliography at the end of the book. 
The lower depth limit of many of the fishes listed is somewhat uncertain, as 
Milner does not indicate their exact distribution inside of 35 meters, but implies 
that they may occur at the depths indicated in the table. Other records bear 
out Milner's implications. 



Common Name 



Scientific Name 



Depth in Meters 



Literature 



Sturgeon 

Crayfish 

Crayfish 

Long-nosed gar 

Lake catfish 

Croaker 

Perch 

Wall-eyed pike 

Large-mouthed black 

bass 

Small-mouthed black 

bass 

Northern moon-eye . . 

Toothed herring 

Tadpole cat 

Carp 

Pike 

Brook silverside 

Stickleback 

\\Tiitefish 

Rock bass 

Amphipod 

Snail 

Long-jaw 

Lawyer 

Lake trout 

Hoy's whitefish 

Amphipod 

Schizopod 

Blackfin 

Small cottoid 



Acipenser rubicundus LeS. 
Cambarus propinquus Gir . 

Cambarus virilis Hag 

Lepisosteus osseus Lirai. . . 
Ameiurus lacustris Wal. . . 
Aplodinolus grunniens 

Raf 

Perca flavescens Mitch. . . . 
Stizosiedion vitretitn Mitch. 

Micropterus salmoides Lac. 

Microplerus dolomieu Lac. 

Hiodon alosoides Raf 

Hiodon lergisus LeS 

Schilbeodes gyrinus Mitch. 

Carpiodes sp 

Esox lucius Linn 

Labidesthes sicculus Cope. 
Eucalia inconstans Kirt. . . 
Coregonus clupeifortnis 

Mitch 

Ambloplites rupestris Raf. 
Eucrangonyx gracilis 

Smith 

Lymnaea lanceata Gld. . . . 
Argyrosomus prognaihus 

Smith 

Lota maculosa LeS 

Crislivomer namaycush 

Wal 

Argyrosomus hoyi Gill 

(MSS) _ 

Ponloporeia hoyi Smith. . . 

My sis relicta Loven 

Argyrosomus nigripinnis 

GiU 

Triglopsis thompsoni Gir . . 



(75, 81) 
(7S,P.iS) 
(7S,P-i5) 
(81, 84) 
(81, 84) 

(84) 
(81, 84) 
(81) 

(81) 



(81, 84) 
(81, 84) 
(81, 84) 
(81) 
(81, 84) 
(81) 
(75, 81) 

(75, 81) 
(81) 

(80) 
(75. 80) 

(75) 
(75, 81) 

(75, 81) 

(75, 81) 
(82, 75) 
(82, 75) 

(75, 81) 
(75, 81) 



CHAPTER VI 

ANIMAL COMMUNITIES OF STREAMS 

I. Introduction 

The conditions in streams from headwaters to mouth have many 
features in common with lakes, like Lake Michigan. It is therefore 
appropriate that they follow the discussion of such a lake. The streams 
belong to two drainage systems — the Mississippi and the Saint Lawrence. 
All are tributary either to Lake Michigan or to the Illinois River. The 
principal tributaries of the lake near Chicago are the Chicago River, the 
Calumet River, Trail Creek, the Galien River, the St. Jospeh River, 
and the Black River. The principal tributaries of the Illinois River, 
with which we are concerned, are the Fox River, the DesPlaines River, 
theDuPage River, the Kankakee 'River, Salt Creek (111.), Hickory Creek. 

The factors of greatest importance in governing the distribution of 
animals in streams are current and kind of bottom. They influence 
carbon dioxide, light, oxygen content, vegetation, etc. 

These factors are controlled by age (physiographic), length of stream, 
and elevation of source above the mouth, all of which are physiographic. 
The typical stream begins as a gully and works its way into the land 
(Fig. 68, p. 112). The importance of some of the factors is greater in 
some stream stages than in others. For example, in the younger stages 
(a) material eroded, (b) relation to ground water, and (c) slope of stream 
bed play a more important role than they do in later stages. 

II. Communities of Streams 
I. classification 
The classification of stream communities is based upon physio- 
graphic history and physiographic conditions. In the early stages of 
stream development there are two types to be distinguished: (a) the 
communities of intermittent streams, and (b) spring-fed streams. As 
soon as the intermittent stream cuts below the ground- water level, 
it becomes much like the spring-fed stream. Permanent streams are 
divided into brooks, swift and moderate, and rivers, sluggish and moder- 
ate, with communities named accordingly. We undertake a discussion, 
first, of the history of the communities of streams developing in materials 

86 



INTERMITTENT STREAMS 



87 



easily weathered and eroded, containing bowlders, gravel, and occasional 
strata of hard rock. 

2. THE INTERMITTENT STREAM COMMUNITIES 

(Stations 4-8; Tables XVII, XVIII) 
There are two types of these — intermittent rapids and pool 
communities. 




An Intermittent Stream 

Fig. 24. — The young stream at Glencoe in spring at high water, showing the 
leaf-barren trees. 

Fig. 25. — ^The same in summer, showing the stream entirely dry. 

a) Temporary rapids consocies (Figs. 24, 25). — Small gullies in 
which water runs only when it is raining do not have any aquatic 
residents. As soon as such a gully has cut a channel deep enough to 
stand below ground-water level during a few days or weeks of the rainy 
season, aquatic insects make their appearance. The species which is 
usually found in the smallest trickle of water is the larva of the black fly, 
Simulium (Figs. 27-32). As the stream grows a little larger, and per- 
haps even at such a young stage also, we sometimes find the nymphs 



ANIMAL COMMUNITIES OF STREAMS 



of May-flies. Such streams have, however, no permanent aquatic resi- 
dents. These aquatic forms are not aquatic during their entire lives. 
They require water only during their early stages. If the water is 
running at the time the female is ready to deposit eggs and if she is 
properly stimulated by the conditions, she deposits them without regard 
to future conditions. If the wet weather continues long enough, the 
larvae will mature and the other adults will appear, otherwise they die. 
This type of animals continues after the stream becomes large enough 





Stream Commxtnities 

Fig. 26. — The pupal case of one of the caddis- worms (Rhyacophila) from the 
rapids of the temporary stream at Glencoe; enlarged as indicated (original). 

Fig. 27. — ^The larva of the black fly (Simulium); about 15 times natural size 
(after Lugger) . 

Fig. 28. — Pupa of the same (after Lugger). 

Fig. 29. — Pupa of the same in the pupal case (original). 

to have permanent pools. At such a stage the number of species is 
increased, but no two collections are alike (see Table XVII). Clinging 
to the upper surface of the stones are black-fly larvae, caddis-worms 
{Rhyacophilidae) (Fig. 26); under stones, May-fly nymphs, those col- 
lected as different times often belonging to different species. On some 
occasions there are great numbers of unidentifiable dipterous larvae 
and caddis-worms without gills or cases. Such a stream may possess 
any or all of these on one occasion, and none or only a few of them on 
another. 



INTERMITTENT STREAMS 



89 




pjg 30.— The eggs of the black fly, about 15 times natural size (from Williston 
after Lugger). Fig. 31.— Side view of the adult fly (from Williston after Lugger). 
Fig. 32. — The same from above (from Williston after Lugger). 



90 ANIMAL COMMUNITIES OF STREAMS 

b) Temporary pool consocies. — As a young stream grows deeper it 
often reaches some depression or marsh at its headwaters of which it 
forms the outlet in the early spring. It is now permanent for a longer 
period each season of normal rainfall, and small pools usually alternate 
with the rapids just described. In these pools aquatic insects, crus- 
taceans, and snails which belong primarily to stagnant ponds make 
their appearance. The first resident species are the crayfishes. They 
are found in the pools in the early spring when the water is high. The 
drying of the stream calls forth behavior suited to the conditions, 
and in summer their burrows are common in the stream bed. They 
come out at night and are preyed upon by raccoons, the tracks of which 
are commonly seen. 

c) The horned dace, or permanent pool communities. — The first per- 
manent parts are permanent pools. In these, conditions such as current, 
sediment, oxygen content, etc., are intermittent or spasmodic. The 
current in the rapids is distinctly spasmodic and conditions in these 
rapids are similar to those in the stream before even temporary pools 
were developed. Streams with permanent pools are represented in the 
Chicago region by many which enter the lake where high bluffs are 
present. County Line Creek (Figs. 24, 25) has been studied as an illus- 
tration of this type (Table XVII). 

The larger pools possess a practically permanent fauna. The char- 
acteristic forms are the crayfishes {Cambarus virilis and propinquus). 
The young are to be found in the pools at all seasons of the year. Water- 
striders, back-swimmers, and water-boatmen are common. Occasionally 
one finds dragon-fly nymphs {Aeshna constricta and Cordulegaster obli- 
quus), dytiscid beetles (Hydroporus and Agabus), crane-fly larvae, the 
brook amphipod (Gammarus fasciatus) , and the brook mores of the sow- 
bug {Asellus communis) (Fig. 55, p. 98). These are common among the 
lodged leaves. They move against water current. 

The species of fish (Table XVIII) which is most commonly found 
in the smallest streams (92) and nearest the headwaters of the larger 
streams is the horned dace or creek chub (Semotilus atromaculatus) (Figs. 
33, 34). It possesses certain noteworthy physiological characters. Like 
many other species of fish, it goes farthest upstream for breeding (50). 
Its nest is made of pebbles. Often after the breeding season is over, and 
the adults have gone downstream, the water lowers so that young fishes 
are left in large numbers in small drying pools. Here they swim about, 
with their mouths at the top of the water, which is constantly being 
stirred up by the many tails, and which often contains much blackened. 



INTERMITTENT STREAMS 



91 



oxygen-consuming excreta and decaying plant materials. This would 
cause death to less hardy fishes. AUee (53) found very little oxygen in 
the waters of such pools. As it is, the pools often dry up, and the fish 
die. The second fish to enter a small stream appears to have many of 
the characters of the first. It is usually the red-bellied dace (Chrosomus 
erythrogaster), which breeds on sandy or gravelly bottom (93) but toler- 
ates standing water, being found also in some of the stagnant ponds at the 
south end of Lake Michigan. In some streams, the black-nosed dace 
{Rhinichthys atronasus) (Fig. 35) is second from the source. These fishes 
go against the current, but avoid the places where it is most violent. 




Breeding Habits of a Pioneer Stream Fish 

Fig. 33. — Showing, in longitudinal section, the nest of a horned dace {Semotilus 
atromaculatus) , with male and female fish in the nest. The stream flows in the direc- 
tion indicated by the arrow at the upper left-hand corner of the picture; | natural 
size (after Reighard) . 

Fig. 34. — Male and female horned dace during the spawning act. Each time 
the male clasps the female she deposits 25 to 50 eggs in the nest. Note pearl organs on 
the head of the male (after Reighard). 



This one also breeds on gravel bottom, and can withstand the stagnant 
conditions of the summer pools. 

As the stream lowers its bed, this type of formation passes gradually 
into a later one. The beginning of the succeeding formation is heralded 
by the coming of the Johnny darter (Boleosoma nigrum), the common 
sucker (Catostomus commersonii) (Fig. 36), and the blunt-nosed minnow 
{Pimephales notatus) (Fig. 37) (79). 

d) Characters of the communities. — The intermittent-stream com- 
munities are made up of animals which are dependent upon water 
during only a part of their lives and which possess a means of attach- 
ment and move against current (94) (positive rheotaxis). The pool 
communities are made up of animals tolerating great extremes of 



92 



ANIMAL COMMUNITIES OF STREAMS 



conditions and being also positively rheotactic. The fish are able to 
meet the current and to withstand the conditions of the stagnant pools. 
The crayfishes live in the water in the spring and burrow in the 




35 




Pioneer Stream Fishes 

Fig. 35. — Black-nosed dace {Rhinichthys atronasus) (from Forbes and Richardson) . 

Fig. 36. — Common sucker {Catostomus commersonii); length 18 in. (from Meek 
and Hildebrand after Forbes and Richardson) . 

Fig. 37. — Blunt-nosed minnow {Pimephales notatus); length 2 to 3I in. (from 
Forbes and Richardson). 



dry weather; adults of the aquatic insects creep into moist places 
when the stream dries. Allee (53) has found that isopods are positiv'ely 
rheotactic and that they can be acclimated to extreme conditions. 



SWIFT STREAMS 93 

3. SPRING BROOK COMMUNITIES 

(Stations 10 and 11; Table XIX) 

In glaciated areas many of the streams are fed by springs which 
have not been produced by erosion, but are the result of porous and 
impervious layers of till arranged as in regions possessing artesian wells. 
The presence or absence and numbers of animals in a spring depend 
largely upon the chemical content of its water. Spring waters commonly 
have insufficient oxygen to support animals and at the same time may 
contain sufficient nitrogen and carbon dioxide to be detrimental if not 
fatal to animals. The mineral matter in solution may be large in 
quantity and in some cases poisonous also. As the water flows away 
from the spring it becomes aerated and diluted with surface water so 
that the animals of the spring brook can live in it. Spring consocies differ 
in different springs because of variations in the character of the water. 

In an area where there are springs, they are usually numerous. 
The little brooks unite to form larger streams. Typically, such streams 
may not be larger than intermittent streams, but a nearly constant 
flow at all times of the year is one of the characteristic conditions. 
Pools and riffles are not so well defined, but contain some small fishes. 
The watercress grows abundantly at the sides of the stream and affords 
a lodging-place for aquatic animals not furnished so abundantly by 
young streams of other types. The water is colder in summer and 
warmer in winter than in other streams. 

Spring brook associations. — Among the watercress are the amphipods 
{Gammarus fasciatus), the larvae of Simulium attached to the leaves, 
beetles, dragon-fly nymphs, and young crayfishes. Here are also found 
occasional snails {Physa gyrina). The species of the cress association 
are nearly all found under stones or on stones in the riffles. On the 
stones are Simulium larvae and Hydropsyche (95), the net-building 
caddis- worm (Figs. 39, 40, p. 96). Under the stones are the nymphs of 
the May-fly {Baetis and Heptagenia), the larvae of flies and midges 
{Chironomus, Dixa, and T any pus), the brook beetles {Elmis fastiditus) 
(Fig. 47, p. 98), and occasional amphipods and crayfishes. 

4. THE SWIFT-STREAM COMMUNITIES 

As the spring brooks and the intermittent streams continue to 
erode their beds, they increase the extent of their drainage systems and 
become larger streams. Springs tend to disappear in connection with 
the spring brook and the intermittent stream reaches the ground- water 
level and becomes permanent. The two sets of conditions converge 



94 



ANIMAL COMMUNITIES OF STREAMS 



toward the larger swift stream (Fig. 38). While the conditions in these 
are like those of the spring brook, the watercress is absent and there are 
few rooted plants. Pools and riffles are well developed and the flow of 
water is constant, but fluctuates in volume. These streams differ in 
size, but the formation mores are practically the same, although larger 
species commonly inhabit the larger stream. 

a) Pelagic sub-formation is very poorly developed in the smaller 
streams and will be discussed in connection with sluggish streams. 









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Fig. 38. — ^The permanent swift stream showing the stones in the rapids, and the 
stiller places below (New Lenox, 111., Gaugars Station) (original). 

6) Hydropsyche or rapids formations (Stations 14, 15, 17, 19, 20, 21; 
Tables XX, XXI, XXII). — These are usually due to the presence of 
coarse material or an outcrop of rock. They are typical in streams with 
large bowlders and stones of all sizes. Here current is probably the 
controlling factor. In these streams, we find the best expression of the 
riffle formation, which we have seen is poorly developed in the smaller 
streams. This formation includes three ecologically equivalent modes of 
life, each meeting the current in a different way. These are (i) clinging 



SWIFT STREAMS 9$ 

to stones in the current, (ii) avoiding the current by creeping under 
stones, (iii) self-maintenance by strong swimming powers. 

Upper surface of stones (stratum i) : Here again we find the black-fly 
larvae, particularly in the smaller streams. They are provided at the 
posterior end of the body with a sucker surrounded with hooks (Figs. 
27-32). The salivary glands are, as is common in insects, modified into 
silk glands and the silk is of such a nature that when it is brought into 
contact with a stone it adheres. The animals are usually found attached 
to the rock by the sucker, with the head downstream. The fans are 
extended and serve to catch diatoms and other floating algae. If for 
any reason the sucker gives way, the animal starts to float downstream. 
If the mouth can be brought into contact with a stone, the silk is exuded 
and the animal is held until it can make the sucker fast again. The 
pupae of this fly are also attached to the stones. They are surrounded 
wuth a cocoon. We have removed them from the stream and have 
found that they cannot make this cocoon in the absence of the current, 
but make a shapeless tangle instead. The adults deposit their eggs at the 
sides of the streams (96). 

On the tops of stones caddis- worms {Hydropsyche sp.) usually have 
cases made of pebbles stuck together with silk (Figs. 39, 40). They also 
have a net for catching floating food. The net faces the current (usually 
upstream) (Fig. 40). The river snail (Goniobasis livescens) (Fig. 54) is 
common on the upper surfaces of the larger rocks and is distinguished 
by a strong adhesive foot. These snails are usually headed upstream. 
When placed in a long piece of eave-trough into which the tap water was 
running at one end, they nearly all made their way to the upper end 
within a short time. They are ecologically equivalent to the caddis-worms 
and the black-fly larvae. 

Among the stones (stratum 2) : Of the animals living among stones, 
the darters are most important. Of these the banded darter (Etheostoma 
zonale) (Fig. 44), the fan-tailed darter {E. flabellare), and the rainbow 
darter {E. coeruleum) (97) (Fig. 45) live among and under the stones or 
in the algae which cover the rocks (especially the fantail). With them 
are sometimes found the Johnny darter (Boleosoma nigrum), the black- 
sided darter (Hadropterus aspro) (Fig. 46), and the small bullhead or 
stonecat {Schilbeodes exilis). These fish are all positively rheo tactic. 
They apparently orient because of unequal pressure on the two sides of 
the body when it is not parallel with the direction of the current. 

Under the stones (stratum 3): There are many more forms living 
under and among the stones than on the tops of them. Here are the 



96 



ANIMAL COMMUNITIES OF STREAMS 



May-fly nymphs, the flattened Heptageninae, and the more or less rounded 
Siphlurus (95) (Figs. 48, 49, 50), evidently succeeding well together. 
This fact makes the value of the flattening as an adaptation appear nil. 
There are also the larvae of midges {Chironomus sp.) (98) and of horse- 
flies (Tabanus) (Figs. 51, 52). The adults of the latter deposit their 
eggs in great masses on the tops of the stones which protrude from the 
water. The stone-fly nymphs, similar to the Heptageninae May-fly 








Representative Aquatic Insects of a Rapids Community 

Fig. 39. — ^The net of the brook caddis-worm (Hydropsyche) seen from the front. 
Drawn from a specimen which made its case against the side of an aquarium (original). 

Fig. 40. — ^The same in its case with the net adjoining the opening which faces 
upstream (original). 

Fig. 41. — The larva of a caddis-fly {Helico psyche) with a case made from pebbles, 
in the form of a spiral; 2I times natural size (original). 

Figs. 42, 43. — The water-penny larva of the brook beetle {Parnidae) seen from 
above and below (43); 25 times natural size (original). 



nymphs in form and appearance, are found here also. Perhaps the 
most bizarre of all are the water-pennies. These are round flat objects 
adhering to the under sides of stones, and not looking like animals at 
all. They are the larvae of a parnid beetle (Psephenus). Figs. 42 and 
43 show two views of a larva. The old larval back becomes the cover 
for the pupa. The adults live under the stones also and their general 
appearance is like that of the parnid in Fig. 47. Sessile or attached 
animals are common in the brooks, but their numbers vary greatly from 



SWIFT STREAMS 



97 



year to year. On one occasion the surface of the rocks and stones in 
Thorn Creek was almost covered with sponge, and while some sponge is 
always to be found, we have not seen it so abundant again. Polyzoa 




v/^/' 




Representative Fishes of a Rapids Community 
Fig. 44. — ^The banded darter {Etheostoma zonale); length 2 in. (from Forbes). 
Fig. 45. — ^The rainbow darter {Etheostoma coeruleum); length 2 in. (from Forbes). 
Fig. 46. — Black-sided darter {Hadropterus as pro); length 3-4 in. (from Forbes). 



are usually present under the stones. Such animals depend upon foods 
in solution and small floating plants and animals. 

In addition to those rapids which have large rocks, are those in which 
the bottom is of coarse sand and gravel, with only a few small stones. 



98 



ANIMAL COMMUNITIES OF STREAMS 




Representative Animals of a Rapids Community 

Fig. 47. — An adult brook beetle {Parnidae); twice natural size (original). 

Figs. 48-50. — Different views of the nymph and adult of the May-fly (Siphlurus 
alter natus); 3§ times natural size (after Needham). 

Fig. 51. — The eggs of a tabanid fly taken from a protruding stone; twice 
natural size (original). Fig. 52. — Adult fly. 

Fig. 53. — A water-strider [Rhagovelia collaris), from the margin of the swift 
brook (New Lenox, Gaugars) ; twice natural size. 

Fig. 54. — The common river snail (Goniobasis livescens), covered with calcium 
carbonate secreted by algae; natural size (original). 

Fig. 55. — An intermittent stream sowbug {Asellus communis); twice natural 
size (original). 



SWIFT STREAMS 99 

Here we find the caddis- worm (Helicopsyche) (Fig. 41, p. 96), which has a 
spiral case made of sand grains. These are most abundant where some 
sand and swift current are both found. There is from time to time some 
vegetation in such situations and on it we find the brook damsel-fly 
nymph (Calopteryx maculata), the adult of which is the black-winged 
damsel-fly. 

Characters of the formation: The swift-stream formation has a 
striking behavior character, namely, strong positive rheotaxis. Other 
physiological characters, such as the toleration of only low temperatures 
and high oxygen content, and the necessity for current for the successful 
carrying-on of their building operations, are probably common to the 
animals. So far as the fishes of the rapids are known, they breed on 
coarse gravel bottom or under stones. The mores of the formation are, 
then, current resisting and current requiring, dependent upon large 
stones or rock bottom for holdfast and building materials. 

c) Sandy and gravelly bottom formation (pools) (Stations 15-22; 
Tables XVII-XXV). — The pools of streams with characteristic forma- 
tions are usually 2 or 3 to 10 feet deep, depending upon the size of the 
stream. The bottom is sand or coarse gravel. In these we find condi- 
tions very different from those in the rapids. The pools are the home 
of the rock bass {Ambloplites rupestris), the small-mouthed black bass 
{Micropterus dolomieu), the sunfishes (Lepomis pallidus and megalotis), 
and the perch {Perca flavescens) , together with a number of interesting 
small fishes whose distribution is shown in Tables XXI and XXII 
(79. 92). 

With these are also the mussels (91), frequently as many as nine or 
ten species, among which are Lampsilis luteola, ventricosa, and liga- 
mentina, the little Alasmidonta calceola (Figs. 57, 58), and Anodontoides 
ferussacianus (Figs. 59, 60), the last-named being perhaps the most 
characteristic of them all. They are often found beneath the roots of 
willows along the sides of the pools. Mr. Isely found that mussels 
migrate to shallow water during flood time. Mussels are dependent 
upon fish for a part of their lives. The young are carried by the adult 
until ready to attach to the body of the fish (99). When they leave the 
fish they are able to take care of themselves. Burrowing in the gravel 
are bloodworms (Chironomus sp.) (95, 98), the burrowing dragon-fly 
nymph {Gomphus exilis), a burrowing May-fly (Fig. 64a, p. 107), a caddis- 
worm, and occasionally snails, Campeloma (Fig. 61 or 64c) and Pleuro- 
cera (Fig. t^d). There are a few plants that grow on the sandy bottom 
in such places, and among these one finds the snail {Amnicola limosa), 



lOO 



ANIMAL COMMUNITIES OF STREAMS 




Representatives of the Pool Community 

Fig. 56. — A long-legged spider taken from a stone out of water in a stream 
(Tetragnatha grallator); twice natural size (original). FiG. 57. — Outside of shell of a 
small mussel from Hickory Creek (Alasmidonta cakeola); natural size (original). 
Fig. 58. — Inside of the same. Fig. 59. — Inside of shell of mussel from Hickory Creek 
(Anodonioides ferussacianus, subspecies subcylindraceus Lea) ; natural size (original). 
Fig. 60. — Outside of the same. Fig. 61. — A snail from the still water of Thorn Creek 
{Campeloma subsolidum); natural size (original). Fig. 62. — A snail from the still 
water of Hickory Creek (Planorbis hicarinatus) , seen from the left; natural size 
(original). Fig. 63. — The same seen from the right. 



SANDY BOTTOMED STREAMS lOI 

occasional aquatic insects, and hair-worms (Gordius). In some localities 
bivalved moUusks (Sphaeridae) and leeches are numerous. 

Under primeval conditions beavers are associated with the pool for- 
mation. They build dams which contribute to the deepening of the 
water of the pools. For a good account of their habits see citation ggb. 
An old beaver dam is supposed to have turned the waters of the 
DesPlaines out of the Chicago River and down the Chicago outlet. 

Characters of the formation: The mores of the pool formation are dis- 
tinctly those of partially burying the body just beneath the surface of 
the fine gravel and moving against the current. The few animals that 
make cases usually use gravel or sand grains. A single caddis-worm 
makes its case from small sticks such as commonly lodge in eddies. 
Some of the fishes breeding in these situations cover their eggs (50) . 
Some fishes orient the body and swim upstream as a result of seeing the 
bottom apparently move forward below as the fish floats down (94). 
They behave the same if put into a trough with a glass bottom and the 
trough drawn forward. Some orient also when their bodies rub against 
the bottom when floating downstream. 

5. the communities of sandy bottomed streams (shifting bottom 

sub-formations) 
(Stations 22-26; Table XXIV) 

We have studied the upper course of the Black River, the upper 
course of the Calumet River, and the Deep River, and two or three 
tributaries of Lake Michigan near South Haven. The kind of material 
eroded is of the greatest importance in determining the mores present in 
a stream. The streams of the eastern part of our area are in till which 
is sandy and their bottoms are sandy. This material is always slipping 
and moving downstream. There are few large stones. The bottom is 
not suitable for animals. The swift-water animals are almost entirely 
absent. The forms present are those which belong to moderately swift 
water. 

Composition and subdivisions. — Such streams are poorly populated. 
Their mores resemble those of the formations of the pools of streams 
eroding coarse material, but the shifting is so much more general and the 
species found so different, that it has been thought wise to separate the 
two. In the Michigan streams there are in summer a few scattered 
plants, which support a considerable number of insects; some of the 
brook beetles (Parnidae) are found attached to them. The logs and 
roots that happen to be in the water are important; they are the only 



I02 ANIMAL COMMUNITIES OF STREAMS 

places that support any amount of life. From these logs I have taken 
hundreds of specimens of small Parnidae, and with them predaceous 
diving beetles (Dytiscidae) which were found hiding in the cracks, also> 
a few scattered caddis- worms (Hydropsyche) . The fauna of the bottom 
is made up of burrowing and semi-burrowing forms. The little dytiscid 
{Hydroporus mellitus Lee.) (99c) is characteristic: it has the habit of 
burying itself in the sand. The bivalved mollusks, especially mussels, 
are present. From the Deep River (upper course) we have taken 
nearly a dozen species. The only snail found is a burrowing form also. 
Animals of such a stream are subject to severe conditions. Many 
of them burrow. The substratum is very unstable and the logs and 
parts of trees to which many of them are attached are free to float down- 
stream with every flood. We know nothing of the reactions of these 
animals to various stimuli. They are distinctly subjects for investi- 
gation. 

6. THE SLUGGISH STREAM COMMUNITIES 

(Stations 19, 27, 28, and 29; Tables XVII, XVIII, XX-XXV) 

There are several phases or types of sluggish stream formations. 
The most important of these are the sluggish or base-level creek, the 
sluggish river, and the drowned river. These are all illustrated in the 
Chicago area. 

The sluggish creek type is illustrated by the west branch of the 
DuPage River and its tributaries; the upper course of the west branch 
of Hickory Creek, Dune Creek, some parts of the Little Calumet south 
of Millers, and the Kankakee and some of its tributaries. 

The sluggish rivers are the Upper Fox, the lower St. Joseph, the 
Grand Calumet, the lower Galien, the lower Black, and others. These 
constitute a group of streams representative of the sluggish type about 
the Great Lakes. ' 

a) Sluggish creek sub-formations (Stations 16, 18). — ^The west branch 
of Hickory Creek has been studied in a cursory manner. The fish are 
a strange mixture of semi-temporary stream and pond forms. The black 
bullhead (Ameiurus mdas) (79) is probably the most characteristic fish. 
The golden shiner (Abramis crysoleucas) and sunfish (Lepomis cyanellus) 
are also found. . 

Baker (100) studied the upper portion of the east-north Chicago 
River. He recorded the same species of Mollusca as were taken in the 
upper part of Hickory Creek. He records also the black bullhead. The 
insects which he mentions are those commonly found in ponds. This 



SLUGGISH STREAMS 103 

community is distinctly of the pond type in its general mores. Stagna- 
tion and low oxygen content and the partial drying of the stream are 
tolerated by all the residents. 

h) Sluggish river formations. — 'The conditions in sluggish rivers are 
different from those in smaller swift streams in many respects. The 
bottom is for the most part of fine materials; there are no rocks. The 
difference between pools and rapids no longer exists. The river is a 
gently flowing mass with relatively little distinction as to different parts. 
The margins of such streams are lined in summer with typical rooted 
and holdfast aquatic plants. The small bays and out-of-the-way spots, 
out of the current, support bulrushes and sometimes cattails. We dan 
distinguish several formations in the Fox River: (i) The pelagic forma- 
tion, (2) the formation of sand and silt bottom (association of sandy 
bottom where the current drags in midstream or beats against the 
shore; association of silt bottom where least current is present), and 
(3) the formation of the zone of vegetation. 

Pelagic formation: This is well developed in the larger rivers, e.g., 
the Illinois River (77). While the Illinois no doubt differs from the Fox 
in many respects, doubtless the general features are much the same. 
It does not differ greatly from that of Lake Michigan. 

Burrowing May-fly or sand and silt bottom formations: On the 
bottom in ten feet of water we have found mussels (Anodonta grandis 
and Quadrula undnlata), the snail {Goniobasis livescens), bloodworms 
(Chironomidae), green midge larvae (Chironomidae). On the old mussel 
shells were large colonies of the bryozoan Plumatella and occasional 
caddis- worms {Hydropsyche) (Figs. 39, 40, p. 96). On sandy bottom, 
conditions near the margin are similar to those on the bottom. We 
find here also an occasional snail {Goniobasis, Pleurocera, and Campe- 
loma), the midge larvae and bloodworms, occasional burrowing May- 
fly nymphs, and a number of mussels {Unio gibbosus and Quadrula 
rubiginosa being the most characteristic). There is also an occasional 
specimen of the long-legged dragon-fly nymph {Macromia taeniolata) and 
the black-sided darter. A considerable number of these species occur 
in the stillest pools of Hickory Creek, indicating the types that will 
dominate later. Silt is often found in particular spots. The most 
characteristic animals in this are the large mussel {Quadrula undulata), 
the burrowing May-fly nymph {Hexagenia sp.), and the bloodworms 
{Chironomidae) . There are also the worms {Annelida) which burrow in 
the mud and protrude their anterior ends, often also the common 
mussel {Lampsilis luteola), the Sphaeridae, and the mud leech {Haemopis 



I04 ANIMAL COMMUNITIES OF STREAMS 

grandis). All of the animals of the silt formation burrow and prob- 
ably require little oxygen. 

Planorbis hicarinatus formation, or formation of the vegetation: 
Here we have for the first time the conditions which we find in ponds — 
a dense rooted vegetation. With such a growth of vegetation we have 
a very different fauna: a large number of aquatic insects and pulmonate 
(lunged) snails. Of these there are a considerable number of species 
which must come to the surface of air, both in the adult and the young 
stages. The most important of these are the bugs: water scorpions 
(Ranatra fusca) , the creeping water-bugs {Pelocoris femoratus) , the small 
water-bug {Zaitha fluminea), the water-boatmen (Corixa sp.), the still- 
water brook beetles or parnids (Elmis quadrinotatus) , several species 
of predaceous diving beetles {Dytiscidae) (ggc), and water scavengers 
(Hydrophilidae). The pulmonate snails are Physa Integra, Planorbis 
hicarinatus (Figs. 62, 63), and often species of Lymnaea. 

Where the bottom is not too soft we often find numbers of viviparous 
snails (Campeloma) and an occasional mussel (Anodonta grandis). The 
crustaceans are distinctly clear- water forms: the crayfish {Cambarus 
propinquus) (loi), the amphipod (Hyalella knickerbockeri) , and the 
brook amphipod {Gammarus fasciatus) (102). 

The gilled aquatic insects are the May-fly nymphs (Caenis and 
Callibaetis sp.) and the damsel-fly nymphs {Ischnura verticalis) and 
dragon-fly nymphs {Aeschnidae and Libellulidae). To practically all of 
these the vegetation is necessary as a resting-place or clinging-place, or a 
place to enable them to creep to the surface to shed the larval skin and 
become adult. 

Variations of the formation: The Fox is fairly representative of 
base-level rivers beyond the reach of tide-water except perhaps that the 
presence of gravel and sand in this stream may not seem fully in accord 
with this statement. There are, as has been noted, rivers near Chicago 
in which these conditions, which go along with old age in a stream, are 
still more marked. The lower Deep River is perhaps a good example of 
this. It is very sluggish and the bottom in the vicinity of Liverpool, 
Ind., is, so far as we have been able to ascertain, entirely covered with 
siltj with considerable humus mixed with it. The margins are peaty. 
The Calumet and the lower Black are similar. In these, sand and 
gravel areas, and animals which inhabit them, are reduced to a mini- 
mum and the silt and vegetation associations are better developed. 

Characters of the formation: The vegetation formation is distinct 
and clearly marked off from all others. The animals are dependent upon 



EFFECTS OF DROUGHTS AND FLOODS 105 

the vegetation for support. The adult aquatic insects must creep to the 
surface of the water to renew their air. The forms that have gills are, 
at least many of them, dependent upon the vegetation for crawling to 
the surface to molt the old skin. The crustaceans are forms that cling 
to the vegetation and the snails must come to the surface for air. Doubt- 
less this formation should be divided into strata, but our data do not 
justify such division. 

III. Special Stream Problems (103, 92) 

The first special problem is that of the relations of animals to seasonal 
changes, to changes in volume of water, amount of silt, shifting of bottom 
materials, and the seasonal aspects of the vegetation. The second prob- 
lem of streams is the historic or genetic, which includes the phenomena of 
the origin of the animals of the stream, their mode of entrance, and the 
effect of rejuvenation, drowning, etc. 

I. SEASONAL CHANGES 

Streams are more strikingly affected by rainfall and drought than are 
any other of. the aquatic habitats. In extremely dry years streams dry 
up in the rapids where they have perhaps not been dry for a century. 
Floods change all the landmarks of the stream bottom and often scatter 
the animals of the stream over the flood-plain. 

a) Floods. — We found at the side of the high bank of the stream 
where the water is quiet at low water, the Johnny darter (Boleosoma 
nigrum), the little pickerel {Esox vermiculatus) , the tadpole cat {Schil- 
heodes gyrinus), the crayfish {Cambarus virilis), and an occasional 
Hydropsyche. Here were also an occasional sphaerid moUusk and one 
or two leeches. 

Caught in a mass of driftwood behind the roots of a tree were case- 
bearing caddis- worms (Phryganeidae), the black- winged damsel-fly 
nymph {Calopteryx maculata), the larvae of the black fly {Similium sp.), 
and two species of May- fly nymphs (one Heptageninae). The last two 
belong to the swift water, the others to the still water or the pools. 
During floods the still- water fauna and the swift- water fauna become 
mixed in the still places. 

At the time of our study there was a growth of rank weeds on the 
flood-plain. While the stream had been swollen for a long period and 
had stood higher than at the time of observation, little or no invasion 
of these weeds by aquatic animals had occurred. Animals evidently 
react negatively to such bottom and vegetation. 



io6 



ANIMAL COMMUNITIES OF STREAMS 



We have had but Kttle opportunity to study the swift-water forma- 
tion during floods, though some of the riffles in Butterfield Creek have 
been studied when the stream was bank full, but no marked changes 
were noted. It is obvious that the extreme floods which move large 
stones crush large numbers of swift-water animals. 

b) Droughts. — There was an unusual drought in the autumn of 1908. 
The data on the distribution of fishes in Glencoe Brook and County 
Line Creek were collected before this date (Fig. 67, p. iii). Table XVI 
shows the arrangement after the drought. 

TABLE XVI 

Showing the Effect of Drought on Fishes 
The localities i, 2, 3, 4 are indicated on the maps of the North-Shore Streams 



(Fig. 67, p. in). P=before drought. *P=after drought. 








Name of Stream and Common 
Name of Fish 


Scientific Name 


I 


a 


3 


4 


Glencoe Brook (no fish) . . . 




P 
P 








County Line Creek 
Horned dace 


Semotilus atromaculatus . 


P 


*P 
P 


*P 


Black-nosed dace 


Rhinichthys aironasus 


*P 


Common sucker 


Catostomus commersonii 




*P 













County Line Creek was entirely dry except the pool nearest its 
mouth in September, 1908, This is locality 4 in Fig. 67, p. iii. 
The following spring was one of normal rainfall. The fish proceeded 
upstream a distance of only three rods. This partially restored the usual 
arrangement. If this represents the rate, the fish proceed upstream 
slowly. Glencoe Brook has not recovered its fish. 

As evidence of upstream migration of Mollusca, the following seems 
to be important. Frequent examination of a section of the North 
Branch of the Chicago River at Edgebrook, between 1903 and 1907, 
showed that Pleurocera elevatum and Campeloma occur in this stream. 
P/ewrocera was not found during this period (ending November, 1907) 
above a certain point. Campeloma was found only sparingly above 
this point. The spring of 1908 was one of heavy rainfall and the 
streams were in flood from April to June. On July 6 the snail 
Pleurocera was found in numbers one-fourth of a mile farther up- 
stream than formerly. Campeloma had gone nearly as far. The sea- 
son from November to April was not different from other seasons 
and there is no reason to assume that the migration began before the 
spring floods. If this is true the snails could make their way toward 



EFFECTS OF DROUGHTS AND FLOODS 



107 



the headwaters at the rate of at least a mile per year, if they were intro- 
duced into a large stream. This must be a response to both water 
pressure and current. The small value of such single observations is 
recognized but they are presented here because the opportunity to secure 
such data is small. In this river there are also notable relations between 
especially dry seasons and the distribution of other animals. The 
season in which the riffles were dry (October 31, 1907) the pools presented 




The Transverse Distribution of Stream Animals 

Fig. 64. — Shows the form of bottom and size of bottom materials in a cross- 
section of the North Branch of the Chicago River, a-d, natural size (original). 

a, a burrowing May-fly nymph (Hexagenia sp.). 

b, small bivalve (Sphaerium stamineum), two individuals, two views. 

c, viviparous snail (Campeloma integrum), seen from two sides. 

d, the long river snail, young and full grown {Pleurocera elevatum). 

Fig. 65. — Cross-section of the stream with reference to a curve. 



an unusual aspect. The standing pools were choked with water-net. 
The minuter forms, such as protozoa and flatworms, were present in the 
greatest profusion. Hydra was abundant. All this is in marked con- 
trast to the conditions which one finds when the stream is running. 

The season following the dry riffles, we found small Hydropsycke 
larvae, and a few young stone-fly nymphs. The only forms present were 
those that could he introduced by terrestrial, egg-laying females. 



Io8 ANIMAL COMMUNITIES OF STREAMS 

In the autumn of 1906 Professor Child found that the May-fly and 
stone-fly nymphs were not present in the riffles but were present in the 
moderately swift and more quiet parts below. The spring of 1906 was 
a dry spring and the females probably laid their eggs in the moderately 
swift instead of the preferred swift water. The distribution is deter- 
mined by the conditions at the time of egg laying. 

We note that even in the larger streams the weather conditions 
affect the presence and absence and abundance of animals. The mores, 
however, remain essentially the same. 

2. TRANSVERSE STUDIES 

Cross-section studies of streams are of interest as showing a hori- 
zontal arrangement of forms belonging properly to different formations. 
This is best illustrated in the cross-sections of curves where there is a 
horizontal gradation of current and in the size of material of the bed. 
Figs. 64 and 65 illustrate this. The burrowing May-fly nymph, belonging 
to the silt, is in the finest materials of the inside of the curve; passing 
toward the center of the stream we next encounter the sphaerid {Sphae- 
rium) and a little farther in the snail {Campeloma integrum) , with it often 
mussels {Anodontoides ferussacianus) ; and still farther into the stream 
we find, clinging to the larger stones, the long snail {Pleurocera elevatum). 
While depth of water may be a factor here, the size of bottom material 
is of first importance. 

3. LONGITUDINAL STUDIES 

(Figs. 66, 67, 68, 69) 

If one passes from the headwaters of a stream to its mouth, he will 
usually find either the spring brook formation or the intermittent 
formation in the upper course, the swift-water formations in the middle 
course, and the sluggish stream or river formations in the lower course. 
There are very numerous variations of this and several of them deserve 
comment. Large streams with a large drainage area and much sedi- 
ment, and with much of the upper part in a young stage, are subjected 
to many changes in the lower courses, such as silting-up at the end of the 
flood periods and washing out later. This often prevents the development 
of the vegetation formation and favors the shifting sand and gravel formations. 

a) Rejuvenation, ponding, and retarding of erosion. — Streams are 
often dammed by some obstruction in their mid course, or erosion is 
checked at a point by a hard stratum, or the stream which has reached 
base-level is rejuvenated by a lowering of the water level at the mouth. 



LONGITUDINAL STUDIES 109 

The obstruction of the hard layer encountered always produces local 
swift water. Above this the water may be sluggish and the area reduced 
to the general level of the obstruction. In the case of rejuvenation the 
head of erosion proceeds upstream; the part of the stream above the point 
to which erosion has reached is sluggish and is sometimes called the pre- 
erosion stream. 

Of the rivers and creeks which we have considered, nearly all the 
larger ones are sluggish or pre-erosion in their upper courses. This is 
true of the DesPlaines, which is held in this condition largely by rock 
at Riverside. Hickory Creek (Fig. 66) is also of this type, the head of 
erosion being at Marley. In passing from source to mouth of such a 
stream we find formations arranged as follows: In the upper sluggish 
courses of all the streams mentioned we find (i) sluggish creek or 
river formations, (2) chiefly swift- water formations below the sluggish, 
(3) chiefly gravel bottom formations below the swift-water formation. 



^ 



// 




Fig. 66. — Diagrammatic profile of Hickory Creek: A, source; B, mouth; C, head 
of erosion; D, rock outcrop. The figures below refer to the columns in Table XXI 
and represent parts from which fish were collected. 

and (4) typical sluggish river formations farthest downstream where 
the vegetation, silt, and sand formations are arranged much as in 
the Fox River. 

Tables XVIII, XXI, and XXII and Figs. 67-69 show the longi- 
tudinal distribution of fishes in six streams. A few moments' study and 
comparison of these tables will make the following facts evident: 

a) The only species in the youngest stream of the North Shore 
series is at the headwaters of all the others. 

b) The species found in County Line Creek are found in the same 
order in the upper courses of Pettibone Creek and Bull Creek; additional 
species are found farther downstream in the larger streams. 

c) The same species are at the headwaters of Thorn-Butterfield and 
Hickory creeks and in the upper courses of the North Shore streams. 
Other species are with them. The species of the North Shore streams 
are crowded together in these large streams which have permanent 



no ANIMAL COMMUNITIES OF STREAMS 

deeper water at their sources (due to springs) and in which the graded 
series of conditions found in the North Shore streams is wanting. 

d) The swift-water fishes begin markedly at the head of erosion in 
Hickory Creek. 

e) The fish communities differ as to species where the conditions 
are very similar, for example, in Thorn-Butterfield and Hickory creeks. 
The general habits of the fishes are the same. 

/) Larger fishes are found in the larger water course and in the down- 
stream portions of the smaller streams. 

g) Fish, when entering a stream, go upstream to a point suited to 
their physiological constitution, regardless of its physiographic mode of 
origin. 

4. GENETIC ECOLOGY OF STREAMS 

Several years ago Adams (103) pointed out that the dispersal of 
aquatic animals is determined by the shifting backward of the head- 
waters and other conditions in streams as erosion proceeds. The forms 
that are in the young streams are moved back as the headwaters are 
moved back and as the river system spreads out into the usual fan shape, 
the animals that belonged in or near the headwaters move backward as 
the conditions migrate backward. In a broad geographic way this is 
unquestioned but details may be studied in the small streams of the 
bluff between Glencoe and the Wisconsin state line. 

Fish are the only strictly aquatic forms in these streams that might 
not have entered by some other method than through the mouth of the 
stream. We have made a study of the fish of these streams for the pur- 
pose of determining whether the fish in the headwaters of the large 
streams are the same as the fish that are found in streams that are just 
large enough to have a single fish species, and the relation of the animals 
to stream development. The changes in animal communities which 
take place at one point are called succession. 

a) Ecological succession. — Ecological succession is the succession 
of ecological types (physiological types, modes of life) over a given point 
or locality, due to changes of environmental conditions at that point. 
From this point of view we have nothing to do with species, except that names 
are necessary. However, we may speak of the succession in terms of 
species whenever their life habits (mores) are not easily modifiable. 

Succession always involves all the animals of a community but it is 
often easier to discuss the changes which take place with respect to one 
group, such as the fishes. It is always to be understood that with changes 
in the fish communities there are similar changes in the communities of 



SUCCESSION OF COMMUNITIES 



III 



Other animals living with them. To illustrate the succession of fish in 
streams we shall consider succession of fish in the North Shore streams. 

b) Statement of ecological succession. — Succession is a reconstruction. 
Here it is based on the superposition of all the fish communities (Fig. 67) 
over the oldest part of the oldest and largest stream. To make this 
clearer we will state, with the aid of the diagram (Fig. 69), the succession 
of fish in Bull Creek. This succession will be considered as taking place 




Fig. 67. — Diagrammatic arrangement of the North Shore streams. The streams 
are mapped to a scale of one mile to the inch, and the maps are placed as closely 
together as possible in the diagram. The intermediate shore-lines are shown in broken 
lines which bear no relation to the shore-lines which exist in nature. Toward the top 
of the diagram is west. Each number on the diagram refers to the pool nearest the 
source of the stream which contains fish, as follows: i, the horned dace {Semotilus 
atromaculatus) ; 2, the red-bellied dace (Chrosomus erythrogaster); 3, the black-nosed 
dace {Rhinichthys atronasus); 4, the suckers and minnows; 5, the pickerel and blunt- 
nosed minnow; 6, the sunfish and bass; 7, the pike, chub-sucker, etc. The bluff 
referred to is about 60 ft. high. The stippled area is a plain just above the level of the 
lake (see Table XVIII). 



over the oldest part of the portion of Bull Creek which lies back of the 
bluff and higher levels of Lake Michigan. This is the point designated 
as 5. (Table XVIII and Figs. 67 and 69 should be before the reader.) 
When Bull Creek was at the stage represented by the first stage in 
our diagram (which is represented by the present Glencoe Brook), its 
fish, if any were present, were ecologically similar to those now in Glencoe 
Brook in their relations to all factors except climate. This ecological 
type is represented by the horned dace alone. As Bull Creek eroded its 



112 



ANIMAL COMMUNITIES OF STREAMS 



bed and became hypothetical stage C of the diagram, the fish community 
of stage I was succeeded by a fish community ecologically similar to the 
fish communities at the localities marked 2 in Fig. 67. The fish now eco- 
logically representing this community are the horned dace and the red- 
bellied dace. The community of the single species, the horned dace, 
had at such a period moved inland to the point where line i-i (Fig. 69) 
crosses the curved line representing the profile of hypothetical stage C. 
As erosion continued, the fish community ecologically represented by 
the horned dace and red-bellied dace moved gradually inland and was 
succeeded by a fish community occupying the mouth of hypothetical 




Fig. 68. — A diagram showing the successive stages in the profile (general shape 
of the bottom) of a very young stream, curved lines, A-B, A-C, A-D, A-E, A-F, 
A-G, A-H representing the successive profiles. The uppermost horizontal line 
represents the surface of the land into which the. stream is eroding. The horizontal 
line with the arrowheads indicates the migration of the source of the stream and 
accordingly of similar stream conditions. The vertical line with arrowheads when 
followed downward passes through a succession of stream conditions and represents 
physiographic succession at the locality B. The point A is the mouth of the stream.' 
Opposite this are shown three successive sizes of the stream, and therefore succession 
at that point. 

stage D, ecologically similar to that now found at the point 3. This is 
represented by the three daces and the Johnny darter. 

As the hypothetical stage D eroded its bed and became stage E, 
which is represented by County Line Creek, fish community 3 was then 
succeeded by a fish community ecologically similar to the fish community 
now present at point 4. This is ecologically represented by the three 
daces, the Johnny darter, and the young of the common sucker. The 
fish communities designated as i, 2, 3 have meanwhile moved inland and 
are arranged in the order which their ecological constitution requires. 

The continuation of the process resulted in displacing a fish com- 
munity ecologically similar to the fish community 4 by a fish community 



SUCCESSION OF COMMUNITIES 



"3 



ecologically similar to the present fish community 5. This is repre- 
sented in the lower waters of Bull Creek — stage F. 

Ecological succession is one of the few biological fields in which pre- 
diction is possible. We may carry this discussion a little farther. We 
have noted that the developing streams continue to erode their beds, 
grow larger, and bring down the surface of the land. These processes 
have not stopped in Bull Creek; it will become larger, contain a larger 
volume of water at the locality 5, and the fish community of locality 5 




Fig. 69.— This figure is based on Fig. 68. The profiles of the streams shown 
here are separated vertically at the mouth. The curved lines represent seven stream 
stages as follows: B, Glencoe Brook; C, hypothetical stage; D, hypothetical stage; 
E, County Line Creek; F, Pettibone Creek; G, hypothetical stage; H, Bull Creek- 
Dead River. The hypothetical stages could, no doubt, be found along the shore of 
Lake Michigan; the difficulty arises from the introduction of sewage into so many 
streams. 

The comparative size of the mouth of each stream stage is represented by a stream 
cross-section at the right. The direction of reading in succession is indicated by the 
vertical line with the arrowheads pointing downward. The oblique lines marked 
i-i, 2-2, 3-3, etc., pass through points in the stream profiles which are in the same 
physiographic condition and occupied by similar fish communities. 

will be succeeded by a fish community ecologically similar to that now 
at locality 6. This stage has been designated as hypothetical stage G 
in the diagram. With a further continuation of the process, the fish 
community of stage G, locality 6, will be succeeded by a fish community 
ecologically similar to that now found at the locality 7 (Dead River) — 
stage H. The communities of every stream have some such history as 
we have reconstructed, but the details may be modified by conditions. 
That branch of ecology which deals with such histories is called genetic 
ecology. 



114 



ANIMAL COMMUNITIES OF STREAMS 



TABLE XVII 

Distribution of Invertebrates in North Shore Streams 
The meaning of the numbers is shown in Figs. 67 and 69. o=Temporary pool 
(consocies); 6 = Very young stream and intermittent riflSes (ephemeral consocies). 



Common Name 

Caddis- worm 

Mosquito larva 

Amphipod 

Isopod 

Snail 

Crayfish 

Black-fly larva 

May-fly nymph 

Crayfish 

Burrowing dragon-fly 

Dragon-fly nymph. . . 

Amphipod 

Snail 

Crayfish 

Crayfish 

Crane-fly larva 

Amphipod 

Snail 

Dragon-fly nymph. . . 



Scientific Name 

Phryganeidae 

Anopheles 

Eucrangonyx gracilis 

Smith 

Asellus communis Say.. . 
Lymnaea modicella Say. . 
Cambarus dio genes Gir . . 

Simulium sp 

Heptageninae 

Cambarus blandingi 

acutus Girard 

Cordulegaster obliquus 

Say 

Aeschna constricta Say.. . 
Gammarus fasciatus Say . 

Physa gyrina Say 

Cambarus virilis Hag . . . 
Cambarus propinquus Gir 
Pedicia albivitta Walk 

(rarely) 

Hyalella knickerbockeri 

Bate 

Planorbis campanulatus 

Say 

Tetragoneuria cynosura 

Say 



STREAM ANIMALS 



"S 



TABLE XVIII 

Showing the Distribution of Fish (Nomenclature after 79) in the North 
Shore Streams at the Times Indicated 

(The numbers refer to Figs. 67 and 69) 



Name of Stream and Common 
Name of Fish 


Date and Scientific Name 


I 


2 


3 


4 


5 


6 


7 


Glencoe Brook 


August, 1907 

Semotilus atromaculalus. . . 

1907-8 

Semotilus atromaculatus. . . 

Rhinichthys atronasus .... 

Boleosoma nigrum 

Pimephales promelas 

Pimephales notatus 

Catostomtis commersonii . . 
September, 1909, and April, 
1910 

Semotilus atromaculatus . . 

Chrosomus erythrogaster. . . 

Rhinichthys atronasus .... 

Boleosoma nigrum 

Catostomus commersonii. . . 
September, 1909 

Semotilus atromaculatus. . . 

Chrosomus erythrogaster. . . 

Rhinichthys atronasus .... 

Catostomus commersonii. . . 

Pimephales notatus 

Esox vermiculatus 

Lepomis pallidus 

Micropterus salmoides .... 

Esox lucius 


* 
* 

? 
* 


* 

* 
* 

* 


* 

* 

* 
* 
* 

* 
* 
* 


* 
* 
* 
* 
* 

* 
* 
* 
* 
* 

* 

* 

* 


■ 

* 

* 
* 






Homed dace 




County Line Creek 

Homed dace 




Black-nosed dace 

Johnny darter 


* 
* 
* 
* 




Blackhead minnow 

Blunt-nosed minnow .... 

Common sucker 

Pettibone Creekf 




Homed dace 




Red-bellied dace 

Black-nosed dace 

Johnny darter 




Common sucker 

Bull Creek-Dead River 

Horned dace 




Red-bellied dace 

Black-nosed dace 

. Common sucker 

Blunt-nosed minnow .... 
Little pickerel 


* 


Bluegill 


1 


* 


Large-mouthed black bass 
Pike 


* 

* 


Crappie 


Pomoxis annularis 

Moxostoma aureolum 

Erimyzon sucetta 

Abramis crysoleucas 

Notropis cornutus 

Notropis cayuga 

Schilbeodes gyrinus 


* 


Red- horse 


* 


Chub-sucker 


* 


Golden shiner 


* 


Common shiner 


* 


Cayuga minnow 

Tadpole cat 






* 
* 



tThe lower part of Pettibone Creek has been destroyed by the United States Naval School, other- 
wise the table would include the records for a point s and perhapts a point 6, but probably not 7 



Note.— Table XIX foUows Table XX. 



ii6 



ANIMAL COMMUNITIES OF STREAMS 



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ii8 



ANIMAL COMMUNITIES OF STREAMS 



TABLE XIX 
Animals of Spmngs and Spring Brooks 
The meaning of the letters in the column headed "Location" is as follows: 
Cs = Gary spring; Gs = Gaugars spring; Zs = Zion spring; Sb = Suman spring brook; 
Cb = Gary spring brook. 



Common Name 

Amphipod 

Planarian 

Planarian 

Dragon-fly njTnph. 

Midge larva 

Black-fly larva .... 

Gaddis-worm 

Midge larva 

Fly larva 

May-fly nymph . . . 

Bivalve 

Amphipod 

Grayfish 

Snail 

Damsel-fly nymph. 
Pamid 



Scientific Name 

Gammarus fasciatus Say. . . 

Flanaria dorotocephala 

Dendrocoelum sp 

Aeschna sp 

T any pus sp 

Simulium sp 

Hydropsyche sp 

Chironomus sp 

Dixa sp 

Heptagenia 

Musculium 

Eucrangonyx gracilis Smith 
Cambarus propinquus Gir. . 

Physa gyrina Say 

Calopteryx maculata Beauv , 
Eltnis fastiditus Lee 



Location 



Gs, Gs, Zs 

Gs 

Gs 

Gs Zs 



Sb 

Sb, Gb 
Cb 
Gb 
Cb 
Cb 
Cb 
Cb 
Cb 
Cb 
Gb 
Cb 



STREAM ANIMALS 



119 



TABLE XXI 

The Distribution of Fish (Nomenclature after 79) in Hickory Creek (and 
Its West Branch) in the Summer of 1909 
Those starred were in the pool nearest the source. I, the first mile of the stream, 
measured from the fish p>ool nearest the source, toward the mouth; II, the third and 
fourth miles; III, at the head of erosion, five miles from the pool nearest the source; 
IV, six miles from the pool nearest the source; V, nine miles from same; stream much 
larger with good riffles and one weedy cove. 



Common Name 


Scientific Name I 


II 


III 


IV 


V 


Horned dace* 


Semotilus atromaculatus . . * 


* 


* 

* 

* 
* 

* 
* 

* 
* 

* 
* 


* 
* 

* 

* 

* 
* 
* 

* 
* 

* 


* 


Golden shiner* 


Abramis crysoleucas I * | * 

Boleosoma nigrum * ! * 

Campostoma anomalum ... * * 




Johnny darter* 




Stone-roller* 


* 


Straw-colored minnow*. . . 
Blue-spotted sunfish* .... 

Blunt-nosed minnow 

Common sucker*. . 

Mud minnow 


Notropis blennius 

Lepomis cyanellus 

Pimephales notaius 

Catostomus commersonii. . . 
Umbra limi 


* 
* 
* 
* 


* 
* 
* 
* 
* 
* 
* 
* 
* 


* 
* 


Top minnow 


Fundulus notatus 




Red-bellied dace 

Chub-sucker 


Chrosomus erythrogaster. . . 

Erimyzon sucetta 

Ameiurus melas 


* 




Black bullhead 


* 


Blackfin 


Notropis umbratilis 

Hybopsis Kentuckiensis . . 

Etheostoma Habellare 

Etheostoma coeruleum .... 




River chub 


♦ 


Fan-tailed darter 

Rainbow darter 


* 
* 


Least darter 


Micro per ca punctulata. . . . 




Sucker-mouthed minnow . 

Cayuga minnow 

Rock bass 


Phenacobius mirabilis .... 
Notropis cayuga 




* 


Ambloplites rupestris 

Notropis cornutus 

Notropis rubrifrons 

Etheostoma zonale 

Lepomis pallidus 

Lepomis megalotis 

Noturus flavus 


* 


Common shiner 


* 


Rosy-faced minnow 

Banded darter 


* 

* 


Bluegill 


* 


Long-eared sunfish 

Stonecat 


* 


Yellow perch 


Perca flavescens 


* 


Small-mouthed black bass 
Hogsucker 


Micropterus dolomieu 

Catostomus nigricans 

Moxostoma aureolum 


* 
* 


Common red- horse 


* 



120 



ANIMAL COMMUNITIES OF STREAMS 



TABLE XXII 

The Fish (Nomenclature after 79) of Thorn Creek, Collection Made at the 
Headwaters in 1908 and 1909 and at Other Points in 
1909 AND 1910 
A = the first fish pool; B = four miles downstream; C = ten miles downstream. 



Common Name 


Scientific Name 


A 


B 


C 


Horned dace 


Semotilus atromaculatus 

Pimephales notatus 


* 

* 
* 


* 




Blunt-nosed minnow 




Blue-spotted sunfish 

Stone- roller 


Lepotnis cyanellus 




Campostoma anomalum 






Notropis umbratilis 




Banded darter 


Etheostoma zonale 




Common shiner 


Notropis cornutus 




Striped-top minnow 

Black- sided darter 


Fundulus dispar 




Hadropterus as pro 




Johnny darter 


Boleosotna nigrum 




Mud minnow 


Umbra limi 




Cayuga minnow 


Notropis cayuga 




Golden shiner 


Abramis crysoleucas 




Large-mouthed black bass. . 
Small-mouthed black bass . 


Micropterus salmoides 




Micropterus dolomieu 




Bluegill 


Lepomis pallidus 




Crappie 


Pomoxis sparoides 




Pirate perch 


Aphredoderus say anus 




Yellow perch 


Perca flavescens 




Carp 


Cyprinus carpio 




Black bullhead 


Ameiurus melas 




Common sucker 


Catostomus commersonii 

Moxostoma breviceps 




Short-headed red-horse. . 




Pike 


Esox hicius 











STREAM ANIMALS 



121 



TABLE XXIII 
Animals of the DesPlaines, Chicago, and DuPage Rivers 
The meaning of the letters in the column headed "Location" is as follows: 
L=Libertyville (still-silt); W= Wheeling (mud-gravel); D = DuPage; R = Riverside 
(swift-stones). Libertyville is the farthest upstream, and the other situations follow 
in the order named. C = Chicago River at Edgebrook, which is added without 
regard to longitudinal order. 



Common Name 



Crayfish 

Snail 

Dragon-fly nymph . . . 

Snail 

Snail 

Crayfish 

Crayfish 

Mussel 

Mussel 

Mussel 

Mussel 

Bivalve 

Snail 

Mussel 

Snail 

Snail 

Snail 

Mussel 

Snail 

Snail 

Stone-flies 

Dobson 

Amphipod 

Caddis- worm 

Isopod 

Damsel-fly nymph. . . 

Dytiscid 

Newt 

Polyzoan 

Pamid 

Caddis-worm 

Leech 

Caddis- worm 

Sialid 

Sphaerid 

Burrowing dragon-fly 
nymph 



Scientific Name 



Cambarus virilis Hag 

Lymnaea humilis modicella Say 

Basiaeschna janata Say 

Ancylus tardus Say 

Ancylus rivularis Say 

Cambarus propinquus Gir 

Cambarus diogenes Gir 

Anodonta grandis Say 

Anodontoides ferussacianus Lea 

Quadrula undulata Bar 

Lampsilis luteola Lam 

Musculium truncatum Lins. . . . 

Goniobasis livescens Mke 

Alasmidonla calceola Lea 

Amnicola limosa Say 

Planorbis bicarinatus Say 

Physa gyrina Say 

Lampsilis ellipsiformis Con . . . 
Pleurocera subulare intensum 

Ant 

Pleurocera elevatum Say 

Perla sp 

Corydalis cornuta Linn 

Hyalella knickerbockeri Bate. . . 

Hydro psyche 

Asellus communis Say 

Argia sp 

Hydroporus vittatus Lee 

Diemictylus viridescens Raf . . . . 

Plumatella sp 

Elmis 

Helicopsyche sp 

Haemopis grandis Verrill 

Phryganeidae 

Sialis sp 

Sphaerium stamineum Con. . . . 

Gomphus exilis Selys 



Location 



R 

R 
R 

R 

R 

R 



D 

D 

D 
D 
D 
D 
D 
D 
D 

D 

D 



D 



C 
W 
C 
W 
C 
W 
W 
W 
W 



122 ANIMAL COMMUNITIES OF STREAMS 

TABLE XXIV 

Mussels of the Calumet-Deep River. Arranged in Order of Longitudinal 
Succession Beginning with the Upper Parts of the 
River at Ainsworth 
The letters indicate place of collection. A= Ainsworth; G = East Gary; 
M = south of Miller, in the Little Calumet; and C = Clark, in the Grand Calumet. 



Common Name 


Scientific Name 


Location 


Mussel 


Symphynota costata Raf 

Lampsilis ventricosa Bar 

Quadrula undulata Bar 

Lampsilis liUeola Lam 

Symphynota complanata Bar, . . 

Unio gibbosus Bar 

Quadrula rubiginosa Lea 

Anodonta grandis Say 


A 
A 
A 
A 
A 


G 
G 
G 


M 
M 
M 
M 
M 
M 




Mussel 




Mussel 

Mussel 




Mussel 




Mussel 




Mussel 




Mussel 


C 







STREAM ANIMALS 



123 



TABLE XXV 
Animals from a Sluggish Portion of Fox River 
The meaning of the letters in the column headed "Location" is as follows: 
Gm = gravel in mid river in eight feet of water; G= gravel near shore; S = sand; 
M = mudorsilt; V = vegetation. 



Common Name 



Scientific Name 



Location 



Snail 

Mussel 

Mussel 

Mussel 

Red midge larva . . 
Green midge larva . 

Caddis- worm 

Polyzoan 

Dragon-fly nymph , 

Crayfish 

Snail 

Snail 

Mussel 

Mussel 

Mussel 

May-fly nymph . . . 

Fly larva 

May-fly nymph . . , 

Amphipod 

May-fly nymph . . , 

Beetle 

Sialid larva 

Snail 

Water-boatman. . 
Water scorpion. . . 

Amphipod 

Bug 

Parnid 

Creeping bug. ... 

Back-swimmer ... 
Dragon-fly nymph 

Leech 

Top minnow 

Snail 



Goniobasis livescetis Mke . . 
Anodonta grandis Say. . . . 
Lampsilis ligamentina Lam 
Quadrula undulata Bar. . . 

Chironomus 

Chironomus 

Hydropsyche 

Plumatella 

Macromia taeniolata Ram. 
Cambarus propinquus Gir. 
Campeloma integrum DeK. 
Pleurocera elevatutn Say. . . 

Unto gibbosus Bar 

Quadrula rubiginosa Lea . . 
Lampsilis luteola Lam.. . . 

Hexagenia 

Slratiomyia sp 

Callibaetis sp 

Hyalella knickerbockeri Ba. 

Caenis sp 

Donacia 

Chauliodes sp 

Physa inlegra Hald 

Corixa sp 

Ranatra fusca Beau 

Gammarus fasciatus Say. . 

Zaitha fluminea Say 

Elmis 4-notatus Say 

Pelocoris femoratus Pal • 

Beauv 

Notonecta variabilis Fieb . . 
Ischnura verticalii Say. . . . 
Glossiphonia fusca Castle . 
Fuitdulus diaphanus 

menona J. and C 

Planorbis bicarinatus Say . 



Gm 
Gm 
Gm 
Gm 
Gm 
Gm 
Gm 
Gm 



M 



M 
M 
M 



V 
V 
V 
V 
V 
V 
V 
V 
V 
V 
V 
V 

V 
V 
V 
V 

V 

V 



CHAPTER VII 

ANIMAL COMMUNITIES OF SMALL LAKES 

I. Introduction 

Lakes are difficult to classify on the basis of animal relations. This 
is because size, shape, exposure to wind, depth, and age are all important 
in determining conditions that affect animals. A classification into 
coastal lakes and morainic lakes will serve our purposes best, because, 
other things being equal, it represents age and depth (near Chicago). 

Morainic lakes are depressions in the moraine due to irregularities of 
deposition, which stand below ground-water level. They are of various 
sizes. We shall apply the term lake only to those bodies of water that 
are large enough to produce an area of at least a few square rods of 
sandy shore, which supports gilled snails, mussels, etc. The principal 
lakes included in our area are shown on the map facing p. 52. The 
largest of these are the Fox, Pistakee, Maria, and Grass lakes in northern 
Illinois; Hudson, Cedar, Stone, and Flint lakes in Indiana; and Paw 
Paw and Pipestone lakes in Michigan. The only coastal lakes of any 
size are Wolf Lake and Calumet Lake. These are located in the old Lake 
Chicago plain. 

I. CONDITIONS IN LAKES 

Depth is important in determining the conditions at the bottom, but 
is of little importance to the other parts of the lake. Little is known of 
the depths of our lakes. Exposure to wind is of importance in affecting 
the waves and circulation of the water (see p. 61), both of which are 
important to animals. A lake well protected by high hills will be likely 
to be less affected by wind than others. Shape is also a factor. Long 
lakes whose long axes are parallel with the direction of the prevailing 
winds are more strikingly affected by the wind than those with the long 
axis at right angles to the wind. 

Waves are never large on small lakes, but are usually effective in 
determining the kind of bottom by controlling erosion and deposition. 
The general circulation of all our lakes has not been studied. On 
account of their small size it is probable that the deeper ones at least 
have an incomplete circulation like that indicated in Fig. 11, p. 61. 
Those that get warmed throughout in summer probably have a complete 
circulation. The dissolved content of the waters of lakes is usually 

124 



LIMNETIC COMMUNITY 125 

similar to that of the large lakes and rivers. Oxygen is usually abundant 
in the surface waters, but is often wanting in the bottoms of lakes (74) 
with incomplete summer circulation. Muck bottoms in deep water 
or in bays have little or no dissolved oxygen. Dissolved nitrogen is 
important, but has been little studied. In the open water light and 
pressure are governed by the same factors as in the large lakes (see 
pp. 62-64). The bottom in small lakes varies with exposure to waves. 
Where the waves are eroding, the bottom is stony or sandy; where deposit- 
ing, it contains silt and humus. There are often deposits of marl, which is 
a calcium carbonate deposit, frequently reaching a depth of 18 feet in the 
Indiana lakes. It frequently reaches to the surface of the water, but 
when it does so is often covered by muck. Muck bottom is common in 
the deeper water and in bays. The vegetation in such lakes is very much 
like that in base-level streams. The vegetation of the shores of rivers 
like Fox River is duplicated in these lakes, and in fact, small lakes are 
strictly comparable to sluggish rivers in many respects. We have 
patches of vegetation, patches of sand and gravel bottom, but also much 
bottom which has more organic matter than river silt. The principal 
difference is that currents in the lakes vary with the wind, and in sluggish 
streams are mainly in one direction. 

II. Communities or Small Lakes 

(Stations 30, 30a, 31; Table XXVI) 
These are divided into the limnetic formation, the formations of 
sandy and stony shores, the formations of muck bottom in shallow 
water, the formations of the vegetation, and the formations of deep 
water (anaerobic). 

I. THE limnetic FORMATION (104) 

(List II) 
The limnetic formation of the smaller lakes is very similar to that of 
the larger lakes. It is made up of the same groups, but with the addition 
of a few pelagic insects such as the phantom larva (Corethra sp.). The 
species of crustaceans, rotifers, and protozoa are different. The char- 
acters of the formation are similar to those of Lake Michigan (p. 75). 

2. shallow water formations 

a) Terrigenous bottom formation (105). — Vegetation, sparse or absent 
— water 0-3 meters. Crawling over the sandy bottom are usually found 
caddis-worms {Goera sp. or Molanna sp.) (Figs. 70, 71). These forms 



126 



COMMUNITIES OF SMALL LAKES 



belong to different families, but have similar cases and similar habits. 
This is a good example of what is meant by mores. The forms are very- 
different, but their mores are similar. The Johnny darter, the straw- 
colored minnow (Fig. 72), and the blunt-nosed minnow are usually 
found (105) in the shallowest water. The Johnny darter, the blunt- 
nosed minnow, the miller's thumb, and probably other minnows breed 
in these situations (105, 106). Crayfish are common here (in Wolf Lake, 
Cambarus virilis). 

Snails (such as Pleurocera subulare [Fig. 73], and sometimes Goniobasis 
livescens) are common on the shoals, crawling over the bottom which is 
always covered with diatoms, desmids, etc. These algae serve as food 

for the mussels. Miss Nichols 
found 16 species of algae on the 
shell of a specimen of Pleurocera 
taken from a Wolf Lake shoal. 
In the deeper waters (3 ft.) we 
find the same crayfishes and the 
same snails fewer in number 
than in the shallower parts of 
the shoals. Associated with 
them are the mussels (especially 
Lampsilis luteola, Anodonta mar- 
ginata and grandis) . Such sandy 
and gravelly bottomed shoals in 
1-3 ft. of water are especially 
important to the food fishes. 
There are many first-class food 
fishes in all such lakes. Of 
those in Wolf Lake seven breed 
in these shallows. There are the large-mouthed black bass (Fig. 74), 
the bluegill, the pumpkinseed, the green sunfish, the perch (Fig. 75), the 
speckled catfish, and the crappie. Nearly all in making their nests 
scrape the bottom clear of all debris; the males guard the nests. The 
number of food fishes in a lake is related to the area of such shoals, which 
are accordingly of great economic importance and should be protected 
from destruction by the encroachment of vegetation and accumulation 
of debris. Associated with the fish are occasional musk turtles (Aro- 
mochelys odorata). Shoals are invaded by bulrushes and bare bottom 
may exist between them. Here the viviparous snail {Vivipara contec- 
toides) (Fig. 76) sometimes occurs. 




Fig. 70. — ^The case of a caddis-worm (Mol- 
anna sp.), sandy bottom (Fox Lake, 111.) 
(original) . 

Fig. 71. — The same from below. 



BOTTOM COMMUNITIES 



127 




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c 






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731 



^ 


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■74 



Repkesentatives of the Bare Sand Community 

Fig. 72. — Straw-colored minnow (Noiropis blennius) (from Forbes and Rich- 
ardson). 

Fig. 73. — Snail {Fleurocera subulare) crawling over sandy bottom; slightly 
enlarged (photographed in aquarium) . 

Fig. 74. — ^Large-mouthed black bass {Micropterus salmoides), juvenile; natural 
size (original). 



128 



COMMUNITIES OF SMALL LAKES 



Characters of the formation : The formation is distinctly dependent 
upon a clean bottom of sand or coarser materials, and is made up of 
creeping forms and those using the bottom as a breeding-place. 




Representative Animals of the Submerged Vegetation 

Fig. 75. — ^Upper fish, the green sunfish (Lepomis cyanellus) ; lower fish, the yellow 
T^x^rch. {Perca jlavescens); both juvenile; slightly reduced (original) . 

Fig. 76. — ^A viviparous snail (Fm/»am co«/ec/ow/M); natural size. 

Fig. 77. — A winter body or statoblast, of the gelatin-secreting polyzoan {Pectina- 
tella magnifica); 10 times natural size (original). 

Fig. 78. — A shrimp (Palaemoneies paludosus) ; twice natural size (original) . 



b) Submerged vegetation association of the open waters. — A lake of the 
coastal type is separated rapidly from the larger body of water in con- 
nection with which it is formed, or a morainic lake, when the ice retreats, 



VEGETATION COMMUNITIES 129 

is left with the greater part of its shallow water of the type which we have 
described. Vegetation is present from the first in the form of floating 
microscopic plants, and the dead bodies of these and of the animals 
present are swept into the depressions and protected situations where the 
waves do not drag on the bottom. Here vegetation grows in the greatest 
luxuriance and causes the production of more plant debris, which adds 
to that already in the protected situations. We then have, after a time, 
a covering of the bottom by the humus and conditions unfavorable for 
most bottom animals. The animals of the bare bottom shoals are no 
longer present in numbers. Small, apparently stunted forms of Lampsilis 
luleola are found for a time, but are soon driven out by the increase of 
humus and vegetation. The early vegetation is made up of scattered 
aquatic plants, such as Myriophyllum and Elodea, and in the shallower 
water usually bulrushes. 

One of the most distinctive and characteristic forms of such lakes is a 
transparent true shrimp (Palaemonetes paludosus), about 2 inches long 
(Fig. 78), which is a close relative of some of the edible marine shrimps. 
In spring they are found carrying numbers of green eggs attached to the 
appendages of their abdomens. Another common animal in these 
situations is the large polyzoan (Pectinatella magnifica). This is a 
colonial form which reproduces by budding in several directions. It also 
secretes a clear and transparent jelly. As the number of animals 
increases the amount of jelly increases on all sides and the animals are 
arranged on the outside of the more or less spherical mass of jelly; the 
necessary increase in surface for the growth of the colony is supplied 
through additional secretion by each new animal added. Some of these 
masses of jelly reach a size of 6 inches in diameter. They are often 
attached about a stalk of Myriophyllum as a center. In the autumn 
they form bodies known as statoblasts (Fig. 77), which are disk-shaped, 
the center containing living cells and the rim being filled with air-bubbles. 
The rim of the disk is supplied with hooks which catch onto objects. 
Probably they must be frozen before they will grow into new colonies 
for they do so only in the spring. 

Other characteristic animals of this open-water vegetation are 
shelled protozoa (Fig. 79), water-mites (Fig. 80), and ostracods (Fig. 81). 
On the stems of the water plants, such as bulrushes and pickerel weed, 
are the snails (Ancylus) which belong to the lunged group, but are said 
to take water into the lung and thus do not need to come to the surface 
for air. Occasional snails, leeches, and midge larvae occur. Water- 
mites fasten their eggs to the bases of the aquatic plants. Among the 



I30 



COMMUNITIES OF SMALL LAKES 



leaves of the divided leaved plants the midge larvae, damsel-fly nymphs, 
and May-fly nymphs {Callibaetis sp.) are usually numerous. All these 
are important as fish food. This area is the feeding-place for a number 
of fishes. Those feeding in the vegetation are the subfishes, basses and 
perches, most of which breed on the barren shoals. With them are also 
the carp, the chub-sucker, the warmouth bass, the brook silverside 
{Labidesthes skculus), and the buffalo fish (84). This part of the lake is 
also the favorite haunt of the turtles (107), such as the soft shell (Aspi- 
donectes spinifer), and in the parts with some bare bottom, the musk 





"^ 



80 "* ^\a 

Fig. 79. — Shelled protozoan {Difflugia pyriformis Perty.) (after Leidy). 
Fig. 80. — ^A red mite {Limnochares aquaticus) ; 6 times natural size (after Wolcott) . 
Fig. 81. — Dorsal view of an ostracod {Cypridopsis vidua); 80 times natural size 
(after Brady). 

Fig. 810. — The same seen from the side. 



turtle (Aromochelys odorata), and the geographic turtle (Grapiemys geo- 
graphicus) . The mud puppy {Necturus maculosus) is also found in such 
situations {fide Mr. Hildebrand). The muskrat {Fiber zibethicus) 
builds its nest (Fig. 82) in the shallow water adjoining these situations. 
The musk turtle frequently deposits its eggs on the nest in early 
summer (105). We have found them in these situations in the month 
of June. Various aquatic birds feed here (108). This formation may 
be characterized as belonging to the aquatic vegetation, but practically 



VEGETATION COMMUNITIES 



131 



all the species are relatively independent of the atmosphere and of the 
bottom. 

c) Emerging vegetation association of bays. — Such situations as are 
occupied by this association are found in bays and protected situations in 
the larger lakes and represent a stage which is last in the history of a 
lake. Water-lilies, water buttercups, and Myriophyllum are the prin- 
cipal plants. Filamentous algae are usually very abundant. Logs, 
sticks, and pieces of wood are not uncommon. 

On the under side of logs, we find such forms as the polyzoan 
(Plumatella) and sponges {Spongilla sp.). On the under side of the water- 
lily pads are usually numbers of Hydra together with great numbers of 




Fig. 82. — A muskrat's nest adjoining the lake border among the bulrushes on 
sandy bottom. 

shelled protozoans and rotifers, especially sessile forms. Snails also are 
common here {Segmentina armigera, Planorbis parvus, Physa gyrina and 
integra, Planorbis campanulatus , and some species of Lytnnaea). 

A large number of species of aquatic insects cling in the vegetation 
with the abdomen near the surface of the water and secure air through 
various anatomical arrangements which conduct it to the spiracles; the 
most noteworthy of these are the water scorpion (Ranatra), the electric- 
light bugs {Benacus and Belostoma), the predaceous diving beetles 
(Dytiscidae) (ggc), the water scavengers (Hydrophilidae) , and the water- 
boatmen (Corixa). There are also a number of aquatic insects that are 
not dependent upon the atmospheric air in their young stages. They 
require, however, some object which reaches above the surface of the 



132 COMMUNITIES OF SMALL LAKES 

water when they emerge from the larval skin. The prominent members 
of this group are the dragon-fly nymphs {Anax Junius and Ischnura 
verticalis). 

There are a few insects that are relatively independent of vegetation 
as a means of attachment. The back-swimmers are an example. They 
float or swim in the water among the vegetation. The commonest of 
these are those belonging to the genera Plea, Notonecta, and Buenoa. 
There are a few fish that have a similar habit. The top minnow 
(Fundulus dispar), which feeds at the surface, is an example. It invades 
the pools near shore and devours mosquito larvae. The young of such 
fishes as the basses and the sunfishes are sometimes taken in these 
situations. 

In the mud of the bottom there are but few animals. Some of these 
are the same species as those found in the bottom in the region of open 
water and will be discussed later. There are, however, forms that live 
only on the rhizomes of the water-lily. Certain of the leaf-feeding 
beetles (Chrysomelidae, Donacia) (109) are aquatic in the young stages. 
The female eats a hole in the leaves of the water-lilies and reaches 
through with her ovipositor and deposits the eggs in a semicircle which 
has the hole as its center. When these eggs hatch the larvae crawl to the 
rhizomes. They are not provided with gills and do not come to the 
surface for air. They have a pair of spines adjoining the spiracles. 
These spines are thrust into the plant and the spiracles which open at 
their bases come into contact with the holes; the gas in the plant and 
the gas in the air tube of the insect's body interchange, and the animal is 
thus supplied with oxygen. When the larva is ready to pupate it spins 
a cocoon in some unknown way under water, but when it is completed 
it is filled with gas, not water, and surrounds the body of the animal. 
The animal then eats a hole, connecting the cocoon with the air spaces 
of the plant. It then pupates and is supplied with oxygen by the plant 
during the entire pupal period. 

The common painted turtle {Chrysemys marginata) and the snapping 
turtle are common in such small bays. They come out upon the logs and 
bask in the sun. The pied billed grebe builds its floating nest, and many 
other aquatic birds feed in such situations (108). 

Characters of the vegetation formation: This formation is of the 
old-pond type which will be especially discussed in the following chapter. 
There are two characters, one or the other of which is possessed by 
nearly all the animals. They depend upon the atmospheric air or must 
have the support of the vegetation, or both. The majority of the ani- 
mals of this formation stick their eggs either in or on vegetation. Such 



SUCCESSION OF COMMUNITIES 133 

formations are quite similar in many respects to the formations of the 
vegetation in sluggish rivers but resist lack of oxygen and stagnant 
water much better. 

d) The anaerobic formation. — This is the bottom and deep-water 
formation. We have already stated that the circulation of water (see 
Fig. 10, p. 61) is not known for any of the lakes discussed. Old lakes like 
those about Chicago are usually covered with humus on the bottom. In 
this humus and probably just above it there is little or no oxygen. 
Analyses of the bottom water from ponds with humus-covered bottoms 
showed that it contained no oxygen. The open water of the lakes with 
the incomplete circulation in summer is without sufficient oxygen to 
support life, below the level of circulation (Fig. 11, p. 61). There 
are, however, numbers of animals that pass the summer under these 
conditions (no, in). These are protozoa belonging to eleven genera, 
worms belonging to two genera, one rotifer, one ostracod, and the small 
bivalve (Pisidium idahoense). Dr. Juday kept these animals in jars 
without oxygen and observed their activities. The rotifer was always 
active. The ostracod showed little activity, and the bivalve kept its 
v-alve closed, showing no activity whatever. 

There are occasional midge larvae in the mud of such bottoms, but 
they are rare. Some of these have haemaglobin in their blood and are 
supposed to be able to use oxygen when it is present in the minutest 
quantities. In the open oxygenless water there are phantom larvae 
(Corethra) which are able to carry a supply of oxygen with them from 
the surface. 

III. Succession in Lakes 

The general tendency of succession in lakes has been indicated. The 
first formation is the bare-bottom type, which is locally transformed to 
the vegetation of open- water type. This usually begins in the protected 
situations first; the bays are ecologically oldest. These bays pass 
rapidly from the third open-lake type to the bay conditions. When such 
a stage has been reached the situations that have a less degree of protec- 
tion from waves have reached the second stage and we have lakes as we 
find most of the larger ones about Chicago. They contain, at various 
points, the three formations which we have discussed. The lake is 
reduced in size by filling near its shores and the lowering of its outlet. 
The older stages are continuously encroaching on the younger. The 
area of barren shoal is constantly becoming less as the lake fills and the 
outlet, if it has one, is' lowered. Around the shores the development of 
prairie or forest is usually well begun and one or the other of these types 
of land vegetation finally displaces the lake. 



134 COMMUNITIES OF SMALL LAKES 

I. THE INFLUENCE OF SIZE AND DEPTH 

Size and depth have a marked influence on the rate of succession. 
If the lake is large, like Lake Michigan, its waves beat upon the shores 
with such force as to prevent the development of vegetation or the 
establishment of any of the formations just discussed. Smaller lakes 
have proportionally less efficient wave-action, and situations which would 
not be protected to any marked degree in a lake like Lake Michigan are 
relatively free from effective wave-action. The formations succeed one 
another rapidly where wave-action is slight. The various parts of the 
shore of a small kettle-hole with a regular shore-line would pass through all 
these stages at nearly the same rate. Depth is an important factor also 
because the various formations cannot succeed over the deep water until 
the deeper parts are filled (or drained), which often requires long periods. 
The rate of succession in lakes is then directly proportional to their size 
and depth. The small lakes pass through all the stages more quickly 
than the larger lakes. Those considered here have for the most part, at 
present, become dominated by the late stages. The lakes of the inland 
type which are large enough to maintain all the formations discussed are 
among the most complex of all our habitats. 

2. INFLUENCE OF MATERIAL AND MODE OF ORIGIN 

At the very beginning the kind of material in which a lake is situated 
is important but as time goes on it becomes less and less important. If 
the lake is in clay, at the outset there are no sandy areas, but the action 
of the waves soon removes the liner material and leaves sand (the finer 
materials being deposited on the bottom of the lake). Young lakes in 
rock are probably very different from those in clay, but even here sandy 
shores are soon formed and occupied by the same animals as sandy 
shores of different origin. 

The distinction between lakes and ponds is a purely artificial one. 
The ponds have the same communities at the outset as the lakes, but 
the changes proceed so rapidly that very young ponds are rare. All 
lakes and ponds tend to become ecologically similar, regardless of mode 
of origin and kind of material . 

LIST II 

The following Entomostraca have been taken from Wolf Lake: * indicates the 
species is found in Fox Lake; f in Butler's Lake; % in the series of ponds at the 
head of Lake Michigan: Copepods: %*] Cyclops serrulatus Fischer; *tt C. albidus 
Jurine; $C. viridis brevispinosus tLervick. Cladocerans: Acroperus harpae Baird; 
X Scapholeberis mucronata Muel.; % Pleuroxus denticulatus Birge; Diaphanosoma 
brachyurum Liev. ; % Chydorus sphaericus Muel. ; Polyphemus pediculus Linn ; Macrothrix 
ro5ca Jurine; t Ceriodaphnia reticulata Juvine; XSimocephalus serrulatus Koch; Bosmina 
obtusirostris Sars. Ostracods: Potamocypris smaragdina Vav. 



SMALL LAKE ANIMALS 



135 



TABLE XXVI 

Animals from Small Lakes 

Meaning of letters occurring in the columns is as follows: "Habitat" column: 

S= bottom of sand; SH = bottom of sand and humus; B = bulrush vegetation; V0 = 

vegetation of open water; VB = vegetation of bays; in "Lake Where Recorded" 

column: F= Fox Lake; W=Wolf Lake; G= Lake George; B = Butler's Lake. 



Common Name 



Scientific Name 



Habitat from 


Lake \ 


Which CoUected 


Recoi 


S 




W 


S 




F 


S 






S 




W 


S 




W 


s 




W 


s 




W 


s 




W 


s 




W 


s 




W,F 


S,SH,B 




W,F 


S,SH 






s 




W,F 


s 




W 


S,SH 






S,SH 






S,SH,B 




W 


B 


VO 




B 


VO 


W,F 


B 


VO 


W,F 


B 


VO 




B 


VO 


W,F 




VO,VB 


W 




VO,VB 


W 




VO,VB 


W 




VO,VB 


W 




VO,VB 


W 




VB 


W 




VB 


F 




VB 






VB 


W 




VB 


F 




VB 






VB 


W 




VB 


F 




VB 


F 




VB 


F 




VB 


W 




VB 


W 




VB 


F 




VB 






VB 






VB 


W 



Caddis-worm 

Caddis-worm 

Caddis-worm 

Snail 

Snail 

Crayfish 

Turtle (musk) 

Geographic turtle .... 
Straw-colored minnow 

Johnny darter 

Mussel 

Planarian 

Mussel 

Mussel 

Polyzoan 

Leech 

Brook silverside 

Snail 

Snail 

Midges 

Amphipod 

May-fly nymph 

Dragon-fly nymph . . . 

Polyzoan 

Shrimp 

Cricket-frog 

Top minnow 

Snail 

Snail 

Snail 

Damsel-fly nymph . . . 
Dragon-fly nymph . . . 
Dragon-fly nymph . . . 

Back-swimmer 

Back-swimmer 

Back-swimmer 

Back-swimmer 

Leech 

May-fly 

Isopod 

Bug 

Beetle 

Beetle 



Goera sp 

Molanna sp 

Polycentropidae 

Pleurocera subulare Lea 

Goniobasis livescens Mke 

Cambarus virilis Hag 

Aromochelys odorata Lat 

Graptemys geographicus LeS . . 

Nolropis blennius Gir 

Boleosoma nigrum Raf 

Lampsilis luteola Lam 

Planaria macidata Leidy 

Anodonta grandis Say 

Anodonta marginata Say 

Plumatella polymorpha Kraep 
Placobdella parasitica Say. . . . 
Labidesthes sicculus Cope .... 

Ancylus fuscus Adams 

Segmentina armigera Say .... 

Chironomus sp 

Hyalella knickerbockeri Bate. . 

Callibaetis sp 

Ischnura verlicalis Say 

Pectinatella magnifica T^idy. . 
Palaemonetes paludosus Gib . . 

Acris gryllus Lee 

Fundulus dispar Ag 

Physa gyrina Say 

Planorbis campanulatus Say. . 

Planorbis parvus Say 

Enallagma sp 

Tetragoneuria cynosura Say . . 

Anax Junius Dru 

Buenoa platycnemis Fieb 

Notonecta variabilis Fieb 

Plea striola Fab 

Notonecta undulata Say 

Macrobdella decora Say 

Ephemerella excrucians Walsh 
Mancasellus danielsi Rich. . . . 

Zaitha jluminea Say 

Coptotomus interrogalus Fab. . 
Donacia sp 



G 



CHAPTER VIII 

ANIMAL COMMUNITIES OF PONDS 

I. Introduction 

Ponds are fascinating to all, and do not lack interest from the scien- 
tific point of view. They are of especial interest to those familiar with 
the laboratory study of zoology. The common animals of the laboratory 
are pond animals, because pond animals are forms that will live in 
stagnant water. The common aquarium fishes are all pond fishes, as 
the brook forms die quickly if they are not supplied with running water. 
The frog, so much studied, is a pond form. The conditions in ponds are 
different from those in lakes and streams, because currents are not strong 
nor particularly important. The water doubtless piles up at one side 
or end of a pond during strong winds, and a complete circulation is 
effected, but this is not important. All of the conditions of lakes are 
duplicated in ponds, but on a smaller scale. One of the chief differences 
between ponds and lakes is the vegetation. Ponds are usually very 
largely captured by vegetation which is very much like that in the bays 
of lakes. Succession of plants in ponds is similar to that in lakes; the 
age of a pond is therefore a matter of first importance. The bottom 
materials are of most importance at the beginning (6, 112). The bottom 
materials in the ponds of the Chicago area are rock, clay, and sand. 
Rock-bottomed ponds have been but little studied, though there are a 
number of ponds in abandoned quarries of different ages which would 
make a good series for investigation. Clay bottom occurs in the moraine 
area. Nearly all the natural clay-bottomed ponds have reached a stage 
at which the bottom is not important, but one could no doubt find a 
good series if he were to make a special study. Sand-bottomed ponds 
are the commonest of all, and for the purpose of studying the effect o"f 
age upon ponds, a series of sandy-bottomed ponds, which differed chiefly 
in the matter of age, was selected. 

II. Area of Special Study 

The ponds that have been made the subject of special study lie in 
the sand area at the south end of Lake Michigan, within the corporate 
limits of the city of Gary, Ind. They may be reached from the stations 
known as Pine, Clark Junction, and Buffington (Fig. 84). The locality 

136 



ORIGIN OF PONDS 



137 



V 











,t the top 
epresents 
the entire 

r the dis- 
e surface; 






« >-' ^ ^ 






« ? t '^^ 






tal ser 
; line a 
om to 
rs. 

he basi 
ot reac 
s. 


^^ 




On 




The horizon 
added. The 
ad from bott 
g of the othe 

is used as t 
3 which don 
nes; (9) oak 










-S^ 




^ 
»- 




pond stages, 
ages A and B 
ake. When re 
•re and the agin 
t Pond 14, and 

aquatic plant; 
nwoods; (8) pi 


\ K 








and vertical series of 
d and hypothetical st 
5hes, the level of the I 
londs near the lake she 
history of the presen 
tom; (2) humus; (3) 
(6) shrubs; (7) cotto 




\ 










he horizontal 
te ones omitte 
occasional das 
le addition of p 
represents the 
(i) sandy bot 
the surface; 




s 




^ ': 




s! ; 


*J c3 >, 'S „ 


* 


i< • 


^ ^ X) tl 't : • -^ 


; 




the relation 
h the interme< 
%-c, indicated 
e area showing 
^,5,1,5,7,1 
id is as follow' 
s which reach 










. ^ *-> ~ si „ c *j 






howing 
inds wi 
he line 
iry of tl 
1 series 
he lege 
ic plan 




/' 






in u +-> rt (_. ^-> 


] ^ 


', 


. — Diagram 
the present 
water level; 
sents the his 
t-hand verti 
uccession. 
es; (5) aqUi 


; 


,." 


•^ -^ 4) It! " j3 




' 


. *> (3 &i rv 3 




Fig 
resen 
grou 
re re 

The 
sion 1 
bulr 







•«C>Vo 



ft a 



^ ^ 



138 



POND COMMUNITIES 



is characterized by a series of ridges running parallel with the shores of 
the lake. Their average width is about 30 meters (100 ft.), and they are 
separated by ponds somewhat narrower. Most of the ponds are several 
miles long and vary in depth, during the spring high water, from a few 
inches to 4 or 5 ft. Originally there were probably a number of outlets 
to the ponds, either connecting them with the lake or with the Calumet 
River. This river flows across the long ponds at a small angle. The 
ponds and ridges were formed under water, and the river has cut its 
way across them with the falling of the lake level. The building of 
sewers associated with the growth of the Northern Indiana towns has 
drained a number of the ponds, and roads and railroads have isolated 
parts of others. 

I. ORIGIN or THE PONDS (62) 

The waters of the lake appear to have fallen gradually from the 12-ft. 
level referred to on p. 47. There are at present usually two or three 
depressions along the shore of the lake under the water. The present 
submerged depressions and ridges appear to be strictly comparable 
to those found on the plain of Lake Chicago, and the ones with which 
we have to deal probably belong to a series formed by the continuous 
recession of the lake level (Fig. 83). This gives us a series of ponds 
differing principally in age, the oldest being farthest from, and the 
youngest nearest to, the lake. 

As has been stated, the ponds have been partly drained, so that we 
have been obliged to study isolated portions. The younger members 
of the series (ist, 5th, 7th, and 14th, as counted from the lake) show the 
greatest differences and have, accordingly, been studied in detail. The 
arrangement of these ponds is shown in Fig. 83. In addition to the 
ponds named, the 13th, the 52d, the 93d, and the 95th have been 
studied, but with less care. 

2. PHYSICAL CHARACTERISTICS (112) 

The main facts of the topography of the isolated portions studied 
are shown in Table XXVIa. 

TABLE XXVIa 



Pond 


Area in Sq. M. 


Depth in Meters 


Average Depth 


Slope 3-7° 


Slope 20° 


I 


3,500 

3,500 

25,000 

10,000 

50,000 

630 


0.6 
0.9 
0.9 

0.667 

O-S 
0.4 


03 
0.5 
O-S 
0.4 
0.2 
O.I 


Much 
Less 

Very little 
Very little 
Very little 
Very little 


Little 


c 


Much 


7 


Much 


14. 


All 


?o 


All 


1:2 


All 







ORIGIN OF PONDS 



139 




I40 POND COMMUNITIES 

A decrease in depth, due to the accumulation of humus and the lowering 
of the ground-water level, is to be noted in the older ponds. The series 
is, then, an ecological age-series, and throughout our discussion we refer 
to earlier and later phases of the various associations concerned. 

III. Communities of Ponds 

I. THE PELAGIC FORMATION 

We have in the ponds a pelagic formation. Though it is limited 
in number of species, many of which breed on the bottom, it is similar 
to that of larger lakes. We have found little difference in the pelagic 
species inhabiting younger and older permanent ponds. Diaptomus 
reighardi has not been taken from ponds filled with the vegetation 
which reaches the surface. Other species are about the same in 
the different permanent ponds. The pelagic formation is poorly 
developed. 

2, PIONEER FORMATION (TERRIGENOUS BOTTOM) 

(Ponds, I, 5, 7) (113) (Stations 9 and 32; Tables XXVII and XXXIV) 
The youngest ponds of the Chicago area are near Waukegan. The 
outer end of the Dead River receives the force of the winter waves from 
the lake and the bottom is bare, with a few scattered aquatic plants. 
Here animals are few. We have taken only a few invertebrates. The 
fish present probably get their food from the older parts farther back 
from the lake. The fish are: the pike {Esox lucius) which prefers clear, 
clean, cool water (79) ; the red-horse {Moxostoma aureolum) which dies 
in the aquarium if the water is the least bit impure, and which also suc- 
cumbs to any impurities in its natural environment (79); Notropis 
cayuga, which prefers clear waters; the common shiner {Notropis 
cornutus) which breeds on bare bottom (105), and the white crappie 
{Pomoxis annularis) which lives in streams. On the bottom at such a 
period one is likely to find the larvae of caddis-flies (Goera sp.), snails, 
mussels, etc., but we have found none in the Dead River, 

Vegetation quickly captures parts of such a pond. Chara is the 
first plant to cover parts of the bottom. After this has happened, the 
pioneer formation may still continue. In Pond i of the series of special 
study (Fig. 85) we have a considerable area of bare sand, and the forms 
present are the caddis- worm (Goera sp.) and the mussels (Anodonta 
marginata and grandis, and Lampsilis luteola). These are preyed upon 
by muskrats (Fig. 86). There are a number of fish that belong to this 



PIONEER COMMUNITIES 



141 



formation because of their breeding relations. The large-mouthed 
black bass, the bluegill, the pumpkin-seed, and the speckled bullhead 
all make nests on the sand, the male fish guarding the nests and driving 
off other fish that approach. These species are the same as those of the 
bare-bottom formations of a lake. In their feeding the fish belong in 
part to another formation in the pond, namely, that of the chara. 

Character of the formation : The formation may be designated as the 
bare-bottom formation, the forms present being those that are dependent 




Fig. 85.— Shows Pond i at the extreme low water of the drought of 1908. In the 
spring the old boat is usually covered with water. In the foreground a large area of 
bare sand bottom is shown; to the right a few rushes and sedges. The absence of 
shrubs near the water's edge should be noted. 



upon bare bottom in their most important activities — the fish in breeding, 
the caddis-worms in making their cases, the mussels in their general 
activities. It is necessary for the mussels to be on bare bottom in order 
to maintain themselves in an upright position. 

Tendencies in the formation : This formation is similar to that of the 
bare bottom of lakes. The vegetation comes in, as has been indicated in 
the protected situations, and the bare bottom disappears, its place being 
taken by the chara. The chara gives rise to humus, upon which chara 



142 POND COMMUNITIES 

will grow for a long time, so the bottom becomes a humus- and chara- 
covered bottom. 

3. THE SUBMERGED VEGETATION ASSOCIATION 

(Ponds I, 5, and 7; Stations 32, 33, and 34) 
The Chara community is entirely different from that of the bare 
bottom, and differs also from that of other vegetations. Chara is highly 
siliceous. It is probably eaten only accidentally by animals or at least 
forms no important part of their food. It should be considered simply as 
a covering for the bottom and a resting- and living-place for animals. 
Some fish culturists (113) have said that it is very rich in life. This 
may be true under certain artificial pond conditions; but the chara 
ponds are poorer than any others of our series. Chara differs from some 
other plants in not reaching to the surface of the water. Many aquatic 
insects that carry air beneath the surface must cling to objects which 
reach the surface when obtaining a fresh supply, and others must crawl 
to the surface on some object in order to emerge from the nymphal skin 
(96). Associated with chara are often growths of bulrushes near the 
sides of the ponds and on the sterile bottom. In the sparse chara the 
most characteristic animal forms are Anodonta grandis footiana (Fig. 86), 
and the musk turtle {Arontochelys odorata), which is abundant on these 
bottoms but is not found elsewhere. There are often nests of a few un- 
identified fishes that clear off the bottom in building. The burrowing 
dragon-fly nymph (Fig. 87) lives on the bottom among sparse chara, in 
the presence of but little oxygen. It lies half buried in the mud, with its 
abdomen protruding a little at the end. The mud minnow (Umbra limi) 
(Fig. 88), the golden shiner (Abramis crysoleucas) (Fig. 88), the chub- 
sucker {Erimyzon sucetta), bullheads, the little pickerel {Esox vermicula- 
lus), the tadpole cat (Schilbeodes gyrinus), and occasionally the warmouth 
bass {Chaenobryttus gulosus) spend their time in the denser chara. The 
shiner and mud minnow place their eggs on the chara or other plants. 

Among the most abundant forms in the association are the midge 
larvae {Chironomus); these (Figs. 89, 90, 91) are present sticking to the 
vegetation in their small silken cases in great numbers (81). They are 
important articles in the food of the fishes. Aquatic insects are not 
numerous except for the midge larvae and a little May-fly. Others 
are occasional horseflies (Fig. 92), damsel-fly nymphs, May-fly nymphs 
{Siphlurus sp.), and occasional dragon-fly nymphs {Tramea, Anax, 
Leucorhinia). There are also a number of dytiscid beetles, many of 
which are common in all shallow waters, even rain pools, because of 
their powers of flight. 



PIONEER COMMUNITIES 



143 



Ecologically one of the most interesting insects is a caddis-worm 
(Leptoceridae), which creeps over the Chara and submerged wood. 
It (Fig. 93) has a case made of the minutest sand grains and pieces of 
humus, such as are stirred up by the waves and which are to be found 




Representatives of a Young Pond Community 

Fig. 86. — The shell of a mussel (Anodonta grandis footiana) that has been broken 
open by a muskrat; slightly enlarged. 

Fig. 87. — The burrowing dragon-fly nymph {Gomphus spicatus), with the mask 
extended. 

Fig. 88. — Some fishes of the pond. The dark fish which rests near the bottom is 
the mud minnow (Umbra limi). The fish swimming about is the golden shiner 
(Abramis crysoleucas) ; i/s natural size. 



among the chara. This species is the successor of the bottom species 
(Goera). It belongs to a different group and has structural characters 
which distinguish it from Goera, but which probably have no relation 
to its habitat or habits. On the other hand, the mores as indicated by 
case-building is also different but is related to the environment. The 



144 



POND COMMUNITIES 



crustaceans constitute an important element in this association. The 
smaller amphipod {Hyalella knickerbockeri) is abundant among the 
chara. The crayfish {Cambarus immunis) occurs here sparingly. In 
ponds there is an important element of small crustaceans that belong 
to the vegetation and the bottom; this element is composed chiefly of 




Representatives of the' Submerged Vegetation Association 

Figs. 89, 90, 91. — ^Larva of a midge (89), pupa of the same (90), the adult. 
Midges are inhabitants of the chara-covered bottom; enlarged about 4 times (after 
Johannsen, Bull. N.Y. State Museum). 

Fig. 92. — The eggs of the common large black horsefly on the tip of the bulrush 
stalk. 

Fig. 93. — ^The chara-inhabiting caddis- worm (Leptocerinae); enlarged as indi- 
cated. 

Fig. 94. — Ostracod {Notodromas monacha Miill.); 30 times natural size (after 
Sharp) . 

Ostracoda (Fig. 94), which are small bivalved forms resembling the 
bivalved Mollusca. They form food for fishes to a small degree. 

Especially abundant just under the chara are the red water-mites 
{Limnochares aquaticus) (Fig. 80, p. 130). One sees numbers of these 



PIONEER COMMUNITIES 145 

when he stirs the bottom. Creeping over the plants are the small 
snails {Amnicola limosa) (Fig. 100, p. 146). These respire by means 
of gills. Other snails are also occasionally present. Physa and Lym- 
naea, etc., are always small or juvenile. We have never taken an adult 
specimen of these from the young ponds and in all only a few specimens 
have been taken. These animals get into the ponds that are formed by 
the removal of sand. We are not at all sure but that the few forms 
found in Pond i are the result of such entrance, rather than the regular 
establishment of the species. 

Among the bulrushes are a few aquatic insects that belong to the 
vegetation that comes above the surface. One of the most characteristic 
forms is the neuropterous larva (Chauliodes rastricornis) (Figs, no, 
III, p. 150), which is a marsh form and will drown in water. 

Characters of the association: This association differs from the 
preceding and from the others generally in being distinctly aquatic and 
also essentially independent of the bare bottom and of the surface. The 
animals of this association are, however, strictly dependent upon the 
vegetation for nesting-places, shelter, etc. The mud minnow has been 
studied experimentally and shows avoidance of direct light. 

Tendencies in the association : This association, like all the others, is 
destined not to last; changes are taking place all the time. The chara 
is filling the pond at the rate of one inch a year (58) and is making a fine 
soil for roots of other plants. As soon as the dense chara stage has 
existed for a time we find other plants, such as Myriophyllum, Pota- 
mogeton, and water-lilies. As soon as these have become established we 
have the commencement of the next association. These plants usually 
appear in spots, and in many cases the zones are much less important 
than in the lakes because of the small areas of the plants. We can, 
however, recognize a zone of water-lilies, and zones or patches of other 
plants. 

Just as we noted that the formations of the bare-bottom type existed 
in the small ponds with the Chara, we see also that the surface-reaching 
vegetation occurs with the Chara association and often ail three occur 
together. Pond 5 contains a poorly developed phase of all three, the 
bare bottom being of minor importance. Pond 7 contains the chara 
association and the surface-reaching association. Ponds 14 and 30 are 
the best expressions of the surface- reaching type, and Pond 52 is 
the last stage of it. This will be discussed more fully, and we will 
pass directly to the association of the vegetation which reaches the 
surface. 



146 



POND COMMUNITIES 



3. THE ASSOCIATION OF EMERGING VEGETATION 

(Stations 34-37> 39; Ponds 5, 7, and 14) (Fig. loi) (30 and 52) 
With the incoming of the water-lilies and the fine-leafed plants, we 
have the inauguration of a new state of affairs. Among the new animals 




Representatives of the Dense Bulrush Association (Pond 5) 
(All about natural size) 

Fig. 95. — ^The common diving spider {Dolomedes sexpunctatus) . The individual 
from which this drawing was made was taken with a nymph of the dragonfly shown, 
in its jaws. 

Figs. 96, 97, 98. — Various stages of a dragon-fly (Leucorhinia intacta) : 96, nymph; 
97, about to shed its outer covering; 98, the adult. (Modified from Needham.) 

Fig. 99. — ^The larva of a caddis-worm {Phryganeidae) , which makes its case from 
bits of grass blades, etc. 

Fig. 100. — Small gill-breathing snail {Amnicola limosa). 

that come in, the bivalved moUusks deserve special mention. The 
Unionidae must have bare bottom for their activities; they are too large 
and heavy to climb on such small vegetation, and the development of 
such a habit has not taken place. They disappear with the sparse 



MATURE COMMUNITIES 



147 



Char a. Their place is taken by other bivalves, viz., the Sphaeridae, such 
as Musculium partumeium, which lives in the humus of the bottom, and 
Musculium secure and truncatum, which live in the vegetation and are 
able to climb on the vegetation and on the side of aquarium jars. 

In the early phases, shrubs and young trees have begun to grow by the 
sides of the ponds and these from time to time fall into the water, thus 
forming a resting-place for many forms that are not found in the other 
situations. Diving spiders (Fig. 95) are common on the bulrushes which 




Fig. ioi. — Showing Pond 14 at moderate low water. In contrast with Pond i 
we see that it is choked with emerging vegetation and the margin occupied by shrubs 
and bulrushes, etc. 



are here growing on a bottom of humus outside leaf-bearing plants 
(Fig. ioi), inside the shrubs. These spiders dive for the immature 
aquatic insects which are here at their maximum. We find numerous 
damsel-fly nymphs and dragon-fly nymphs, both the creeping form {Leu- 
corhinia intacta) (Figs. 96, 97, 98) and the climbing form. The burrow- 
ing dragon-fly nymph has gone, or is present in small numbers only, and 
there are but few May-fly nymphs. Those that persist creep about on 
submerged sticks in company with Amnicola and are especially likely to 
occur in the earlier phases of this community. With these occur the 



148 POND COMMUNITIES 

caddis- worms (Phryganeidae: Neuronia) (Fig. 99), which are also abun- 
dant in the later stages of dense vegetation. This worm's case is some- 
what similar in form to that of Leptoceridae, being a circular tube, but it 
is made of pieces of grass blades or other pieces of plant fragments instead 
of sand grains. The pieces are fastened together with silk. The worm is 
found creeping among the vegetation, drawing its case after it. Amnicola 
(Fig. 100), the river-dwelling snail, is common, especially on twigs and 
logs. In the mature stage represented by Pond 14 (Fig. loi) the com- 
mon newt (Fig. 102) probably reaches its maximum abundance. The 
snails which are at best advantage in these ponds are the lung breathers. 
They can here come to the surface for air, and food is abundant, as the 
surfaces of the plants are covered with algae and these form the food of 
the snails. Those snails which come to the surface for air are common. 
Planorbis campanulatus (Fig. 103) is characteristic of the mature stage 
and Lymnaea reflexa (Fig. 104) in the older stages. The individuals in 
this case are larger than those of the temporary marshes (cf. Figs. 104 
and 125, pp. 149, 17s). Planorbis parvus (Fig. 105) is commonest in the 
earliest phases and Planorbis hirsutus (Fig. 106) in the later. Diving 
beetles (Fig. 107), which are common throughout, are most numerous 
in the denser vegetation. The soldier-fly larvae (Fig. 108) are often 
common in the dense filamentous algae of the mature phases of the asso- 
ciation; here the number of all dipterous larvae is greater than at any 
other point. Midge larvae occur in great numbers, having their cases 
among the algae. Horseflies (Fig. 92), also Tanypus, Ceratopogon, and 
some mosquitoes are present. Specific identification, however, is not 
possible, and whether or not the species differ in modes of life or reactions 
from those inhabiting the earlier stages in the pond series has not been 
determined. 

Adult aquatic insects have increased with the increase in vegetation, 
in a remarkable fashion. The prominent forms are the larger bugs, such 
as the electric-light bugs (Zaitha fluminea and Belostoma americana 
Leidy, with Benacus griseus Say). The water-boatmen are also common. 
The species of these are not well known, and we cannot say whether or 
not they are the same in the older and younger ponds. Back-swimmers 
are also abundant {Notonecta variabilis and undulata, Buenoa platycnemis, 
and the small form. Plea striola, occur here). They are few in number 
or absent from the younger ponds. 

Some animals particularly abundant in the older stage are the 
common leech {Placobdella parasitica) (Fig. 109), the larvae of a netted- 
winged insect {Chauliodes rastricornis) (Figs, no, in), the large flat 



MATURE COMMUNITIES 



149 



snail {Planorhis trivolvis) (Fig. 112), and the amphipod {Eucrangonyx 
gracilis) (Fig. 113). All these occur in the senescent stage, where in 
dry years the pond goes almost dry. The vertebrates of the mature 
and later stages are not numerous. The fish are limited to mud- and 
muck-preferring species, the black bullhead {Ameiurus melas) and the 
mud minnow {Umbra limi) (106). The grass pickerel and the dogfish 
are found in such vegetation-choked ponds. 




Representatives of the Emerging Vegetation Association (Pond 14) 

Fig. 102. — The common newt (Diemictylus viridescens); natural size (after Hay). 

Fig. 103. — A flat pond snail (Planorbis campanulatus); natural size. 

Fig. 104. — The common pond snail (Lymnaea reflexa); natural size. 

Fig. 105. — Small flat snail (Planorbis parvus); 3 times natural size. 

Fig. 106. — ^A snail (Planorbis hirsutus) ; 3 times natural size. 

Fig. 107. — ^A predaceous diving beetle (Cybister fimbriolatus Say); natural size. 

Fig. 108. — A soldier-fly larva — unidentified; twice natural size. 

The amphibia are the frogs which occur in all stages of the associa- 
tion, and the common salamander {Ambly stoma tigrinum), which burrows 
in the soft mud where it remains during the greater part of the year. 
It comes out in spring (February or March) and deposits eggs in the 
pond, where the young are found later. Of the turtles the common 



ISO 



POND COMMUNITIES 



painted turtle {Chrysemys marginata) is abundant, basking on the fallen 
trees. The geographic turtle and the snapping turtle are found also 
in the younger phases. Garter-snakes pick up their food along the 
ponds (Fig. 114), while muskrats, occasional minks, and various aquatic 
birds (108) feed in the ponds. 




Senescent Pond Inhabitants 

Fig. 109. — ^A leech with young attached to the ventral side {Placobdella para- 
sitica) ; natural size. 

Fig. iio. — The larva of a netted-winged insect {Chauliodes raslricornis) . 

Fig. III. — Pupa of the same (slightly enlarged). 

Fig. ti2. — A.?,nsJi\.{Planorbis trivolvis); natural size. 

Fig. 113. — Common amphipod {Eucrangonyx gracilis); twice natural size. 

Fig. 114. — Pond 58 in a dry season, showing dead fish (mud minnows) both 
on bottom and out of water and in the water. A garter-snake (Thamnophis sp.) 
feeding on the fish. 

Consocies of logs. — ^This is the chief place to find the sponge and the 
polyzoa. Their numbers vary from year to year but they are usually 



SUCCESSION OF COMMUNITIES 1 51 

present. With them are often found leeches, especially Macrohdella 
decora, which is a brilliant red-and-green form. The only character- 
istic insect is the dytiscid beetle (Agabus semipunctatus Kirby) (99c), 
a slender reddish-brown form. The other forms found here are inci- 
dental in the vegetation. Hollow logs are probably used for breeding- 
places by the fishes, such as the bullheads (105), while the eggs of Physa 
and of water-mites, and some of the aquatic insects, are also placed here. 
The mammals of these ponds are the muskrat, which occurs in all the 
stages, and the mink, which is now rare. 

Tendencies of the association: This association is unstable. Its 
fate is heralded by the incoming of different amphibious plants at the 
sides. This is the form Proserpinaca, with the divided leaves above 
water and the entire ones below. This is often associated with Equisetum 
and plants that have the growth form of grasses. Following these are 
the shrubs, such as the buttonbush (6). Before these have captured 
the entire pond it becomes dry during the dry season and the end of the 
aquatic community is come. The formation which follows is the tempo- 
rary pond, swamp, or marsh type. 

Characters of the formation: The formation composed of the two 
associations mentioned may be characterized as made up of forms 
which require but little oxygen, and no bare bottom. The reproduction 
is one of two types: either the young are carried or the eggs are attached 
to plants. Some of those carrying the young are the Sphaeridae, the 
amphipods, and the isopods. Those sticking the eggs onto or into the 
vegetation are the snails (all), the Dytiscidae, all the species recorded, the 
Hydrophilidae, the Notonectidae, the Belostomidae, the Ranatras, the 
caddis-flies, the Donacias, and in fact most of the forms of the formation. 

IV. Succession 

The first formation to take possession of a pond when it is first 
separated from a lake like Lake Michigan is the bare-bottom formation; 
chara soon makes its appearance in the deeper parts and we have the 
beginning of the chara association. The chara association so acts upon 
the bottom by covering it with humus and vegetation that it renders 
the continued existence of the bare-bottom formation impossible (6, 
112, 114, 114a). At the same time it prepares a way for the vegetation 
which reaches to and above the surface. This, in turn, fills the pond 
still further, and the strictly marsh vegetation takes possession. The 
history of the true pond is then at an end and the story of the marsh 
begins. Our series of 95 ponds illustrates the series of stages. The 



152 POND COMMUNITIES 

vegetation which comes to the surface of the water and the later marsh 
and swamp vegetation encroach from the sides toward the center. 

Entomostraca do not ordinarily show so clear a succession of species 
as do other groups and our collections are very incomplete. The follow- 
ing have been noted: Cladocerans: Ceriodaphnia reticulata Jurine, C. 
pulchella Sars, and C. quadrangula Muel. from Ponds 52 to 93. 
Copepods: Cyclops albidus Jurine appears more common throughout 
the series and C. viridis Jurine is common in the older ones. Diaptomus 
reighardi Marsh is in the younger ponds and its place is taken by 
D. leptopus Forbes beginning with Pond 30. Of the ostracods, Cypria 
exsctdpta Fisch. is common throughout the series. Cypridopsis vidua 
Mull, is common in the semi-temporary ponds. 

I. FATE or THE PONDS 

In the late stages the pond dries during extreme droughts and passes 
rapidly from the stage at which it dries occasionally during a dry season 
to the stage when it dries every season. It is then known as a marsh or 
swamp, or often vernal marsh or swamp, or summer dry pond. At such 
a stage it is a land habitat in summer and a water habitat in spring. As 
the pond bottom is built up higher by the accumulation of peat, and the 
surrounding ground- water level is lowered by the forces of erosion, the 
question of what is to become of the pond brings us to a question of great 
importance in connection with climatic formations. It will become what- 
ever the surrounding climatic formation may be. If it is forest, directly 
or indirectly, the pond becomes forest, and if it is steppe the pond be- 
comes steppe, while if prairie or savanna the pond becomes savanna. 

We have already noticed that the area of study is on the border of 
the forest and prairie (steppe formations). A pond in the area of study 
may therefore become prairie or forest. Ponds with sloping sides usually 
become prairie, and those with steep abrupt banks or shores turn into 
forest. There is no marked difference between the animal life of the two. 
Collections made in a series of three prairie ponds which are situated 
near Wolf Lake, Ind., and which in ecological age may be compared with 
Ponds 1,7, and 14 of the Lake Michigan series, are almost parallel with 
the collections from the Lake Michigan ponds. The differences to be 
noted are that the snail Planorbis trivolvis, which usually occurs in old 
ponds only, is found in the earliest pond of the prairie pond series, while 
the snail Vivipara contectoides and the shrimp Palaemonetes pcdudosus, 
which usually occur only in streams and small lakes, also occur in the 
prairie pond series . The presence of the latter two may be explain ed, how- 
ever, by the fact that the ponds were once connected with Wolf Lake. 



POND ANIMALS 



153 



In the pond formation proper, the fate of the pond early becomes 
evident along the margin. This will be discussed in connection with 
swamps and marshes. The discussion of the areas properly called 
marshes and swamps is the most complex of all our discussions, and will 
be taken up in the chapter on swamps, marshes, and temporary ponds. 

Tables XXVII-XXXIII show animals recorded from the series of 
ponds at the head of Lake Michigan (Stations 32-37). 

TABLE XXVII 

Sponges 





Pond Numbers 


Name 


I 


s 


7 


14 


30 


52 


93 


95 


Meyenia{ f) crateriformis Pot. . . . 

Meyenia flimatilis Auct 

Heteromeyenia argyrosperma Pot . 
SpongUla fragUis Leidy 


* 


♦ 


* 
* 








* 





TABLE XXVIII 
Leeches 



Name 



Pond Numbers 



Glossiphonia fusca Castle . . . 

Dinafervida Verrill 

Erpobdella punctata Leidy . . 

Macrobdella decora Say 

Haemopis grandis VerriU. . . 
Placobdella parasitica Say . . 
Placobdella rugosa Verrill . . . 
Glossiphonia heteroclita Linn 
Haemopis marmoratis Say . . 



TABLE XXIX 
Sphaeridae and Unionidae 





Pond Numbers 


Name 


I 


1 
SC 1 7« 


146 


30 


52 


93 


95 


Unionidae — 
Lampsilis luteola Lam 


* 

* 
* 


1 


? 

* 


* 
* 

? 


* 


* 
* 




Anodonta grandis Say 


* 
* 
* 

* 


* 
* 




Anodonta marginata Say 

Anodonta grandis footiana Lea. . . 
Sphaeridae — 

Musculium truncatum Lins 

Muscttlium secure Prime 

Musculium partumeium Say 





154 



POND COMMUNITIES 

TABLE XXX 

Snails 





Pond Numbers 




I 


Sc 


70- 


145 


30 


S2 


03 


03 


Amnicola — 
A mnicola limosa Say 


* 
* 

F 

* 

F 

* 
* 
* 
* 
* 

F 


* 
* 

F 

F 

* 

* 
F 


* 
* 
* 

c 

* 

* 
* 
* 

c 

* 


* 
* 
* 

c 

* 

* 
* 
* 

A 
C 


c 

* 

A 

A 

? 


« 
* 
* 

* 
* 


* 
* 

* 
* 




Amnicola cincinnatiensis Lea. . . . 

Amnicola limosa parva Lea 

Physa — • 
Physa gyrina Say 




Physa heterostropha ? Say 

Lymnaeidae — 

Lymnaea rejlexa exilis Lea 

Planorhis bicarinatus Say 

Lymnaea humilis modicella Say. . 
Lymnaea obrussa Say 




Planorhis parvus Say 




Planorhis campanulatus Say 

Planorhis hirsutus Gld 




Planorhis exacuosus Say 

Lymnaea rejlexa Say 




Planorhis deflectus Say 




Planorhis trivolvis Say 




Segmentina armigera Say 


? 



TABLE XXXI 

Crustacea 



Name 


Pond Numbers 


1 


Sc 


^a 


146 


30 


52 


93 


OS 


Hyalella knickerhockeri Bate 

Eucrangonyx gracilis Smith 

Mancasellus danielsi Rich 

Asellus communis Say 


C 
F 


C 

F 

F 


C 
C 

C 
F 


F 
A 

C 
F 


F 

A 

* 

* 

C 

? 


A 

* 
* 

* 
* 


A 

* 

* 
* 


F 

* 


Camharus immunis Hagen 

Camharus hlandingi acutus Girard . . 


* 



POND ANIMALS 



155 



TABLE XXXII 

Aquatic Insect Larvae and Nymphs 



Name 



Pond Numbers 



7a 146 30 52 93 95 



May-flies — 

Siphlurus sp 

Caenis sp 

Callibaetis sp 

Neuroptera — 

Chauliodes raslricornis Ram . . . . 
Damsel-flies — 

Lestes sp 

Enallagma sp 

Ischnura verticalis Say 

Dragon-flies — 

Tramea lacerata Hagen 

Celithemis eponina Drury 

Libellula pulchellaDTury 

Gomphus spicatus Selys 

Leucorhinia intacta Hagen 

Anax Junius Drury 

Sympeirum rubicundulum Say . . . 

Sympetrum sp 

Pachydiplax longipennis Burm. . . 

Epiaeschna heros Fab 

Caddis-worms — 

Goera sp 

Leptocerinae sp 

Neuronia sp 

Diptera larvae — 

Chironomid larvae 

Stratiomyid larvae 

Tanypus sp 

Tipulid larvae 

Ceratopogon sp 

Hemiptera — 

Ranatra kirkaldyi Buen 

Corixa sp 

Ranatra fusca P.B 

Zaitha fluminea Say 

Notonecta undulata Say 

Buenoa platycnetnis Fieb 

Notonecta variabilis Fieb 

Plea striola Fieb 

Water-striders — 

Gerris rufoscutellatus Lat 

Gerris marginatus Say 

Mesovelia bisignata Uhl 



156 



POND COMMUNITIES 



TABLE XXXIII 
Distribution of Fish: Ponds Arranged According to Ecological Age 
For meaning of numbers and letters see Fig. 84, p. 139. 



Common Name 



Large-mouthed black bass. 

Bluegill 

Blue-spotted sunfish 

Pumpkin-seed 

Warmouth bass 

Yellow perch 

Chub-sucker 

Spotted bullhead 

Pickerel 

Mud minnow 

(jolden shiner 

Yellow bullhead 

Black bullhead 

Dogfish 



Scientific Name 



Micropterus salmoides . . 

Lepomis pallidus 

Lepomis cyanellus 

Eupomotis gibbosus . . . . 
Chaenobryttus gulosus . . 

Perca flavescens 

Erimyzon sucetta 

Ameiurus nebulosus . . . . 

Esox vermiculatus 

Umbra limi 

Abramis crysoleucas. . . . 

Ameiurus natalis 

Ameiurus melas 

Amia calva (juvenile) . . 



Ponds 



146 



52 



TABLE XXXIV 
Higher Vertebrates 



Name 



Pond Numbers 



SC 


70 


146 


* 






* 


* 


* 


* 


* 


* 


* 






* 


* 


* 


? 


? 


? 



30 
52 



Aromochelys odorata Lat . . . 

Rana pipiens Sch 

Chrysemys marginata Ag . . . 
Graptemys geographicus LeS 
Diemictylus viridescens Raf . 
Fiber zibethicus Linn 



CHAPTER IX 
' CONDITIONS OF EXISTENCE OF LAND ANIMALS 
I. Introduction 

Man being a land animal, it is natural that he should be more familiar 
with the conditions of existence of land animals than with those of aquatic 
forms. The reader will recognize that the primary divisions into which 
land animals may be divided are (a) those living exposed to the atmos- 
phere on the surface of the soil and of plants and animals, and (6) those 
out of direct contact with the atmosphere, in the soil, in wood, and in the 
tissues of living plants and animals. The solid substances in and upon 
which animals live are called materials for abode (55, 115) and, aside from 
soil, materials are just as varied as are the living and decaying bodies of 
plants and animals. For this reason, an adequate discussion of such 
materials for abode would require a separate treatise. Since the laws 
governing the physical conditions surrounding animals living hidden 
away, for example in the bodies of living and dead organisms, are little 
known, we will pass directly to a discussion of the conditions of existence 
of animals living in soil and exposed to atmosphere. 

II. Soil (116) 

Because of its importance in agriculture, the relation of plants to soils 
has been much studied. The laws governing plants in their relation 
to soils apply in the main to soil- inhabiting animals, all the various 
properties of soils being of some importance in this connection. 

I. TEXTURE 

The texture of soils is of importance to animals because of the vary- 
ing difficulty with which they may burrow into it, and the ease with 
which their burrows are maintained when once dug. Particular animals 
prefer soils of a particular texture, some preferring rock, some sand, etc. 

2. WATER 

Most subterranean animals are submerged in water during rains. 
The amount of water which they encounter in the soil at other times is 
determined to a large extent by their relation to the water table (57), and 
by the character of the soil. The water-holding power of different soils 
is different. It increases with the decrease in size of the soil particles and 

157 



IS8 TERRESTRIAL CONDITIONS 

with the addition of humus which takes up water by imbibition. The 
amount of water in the soil is usually expressed in terms of per cent of 
weight, but a soil with 8 per cent of moisture may not give up water to an 
organism as readily as another soil with only 2 per cent. It is necessary 
therefore to determine the capacity of a soil to retain or give up moisture. 
This has been determined for, a number of soils (117, 118), in terms of 
what is called the moisture equivalent. The moisture equivalent of a 
soil is the percentage of water which it can retain in opposition to a cen- 
trifugal force 1,000 times that of gravity. The maintenance of turgor 
in plants is believed to be a purely physical matter. If the roots of a 
plant are in a mass of soil, the plant gradually reduces the water content 
until the permanent wilting occurs. The willing coefficienl of a soil is 
the moisture content (in percentage of dry weight) at the time when the 
leaves of the plant growing in the soils first undergo a permanent reduc- 
tion in moisture content, as a result of a deficiency of moisture supply. 
The moislure equivalenl of a soil is i . 84 times the willing coefficient for 
wheal, used as a standard plant. Fuller (119) states that the wilting 
coefficient of dune sand is about o. 75 per cent, while the usual moisture 
content of the cottonwood dune sand is two or three times this amount. 
For the clay soil of the oak-hickory forest, according to McNutt and 
Fuller (i 19a), the coefficient is about 8 per cent. These standards of soil 
moisture indicate the amount of water available to animals through 
direct contact with the soil or available for evaporation into the air of 
cavities which they construct for themselves beneath the surface of the 
soil. A soil gives water to or takes water from the body of a subter- 
ranean animal in proportion to the availability of water in the soil in 
question. The amount of available water increases with depth (119). 

3. TEMPERATURE 

Transeau found that the temperature of bog soil and bog water is 
below that of other soils and waters. This has, however, not been 
observed for different dry soils. The differences between soil on the 
beach at Sawyer, Mich., August 19, 191 1, at 3:00 p.m. and in the beech 
woods near at hand was as follows: Air 20° C, upper half -inch of beach 
sand 38°-39° C, sandy soil of beech woods i9°-2o° C, a difference of 
19° C. The upper half -inch of bare sand goes as high as 47° C. on the 
hottest days of summer, while the soil in the beech woods is probably 
always a little cooler than the air at the time of the air maximum. 
Dune sand temperature on the hottest summer days at about 3 : 00 p.m. 
has been found to be as follows: 



ATMOSPHERE 159 



TABLE XXXV 



Showing Variation of Sand Temperature with Depth and Moisture Content* 

Air 36° C. 




Moist Sand 



1 . 25 cm. below surface . 

3-4 cm. below surface . 

8-9 cm. below surface . 
10-11 cm. below surface. 
12-13 cm. below surface. 
17-18 cm. below surface. 



32° C. 
31° c. 
29° C. 

27° C. 



It will be noted from the table that temperature decreases with depth 
and with increasing moisture. 

4. PLANTS AND ANIMALS 

Cowles (120) mentions the importance of soil bacteria which increase 
with the increase of the humus, and the development of substances toxic 
to the plants producing them (121, 114a). Little is known of the effect of 
animals upon the soils in which they live but if excretory products ever 
accumulate in any quantity, they probably have a detrimental effect, 
especially upon the animals which produce them (114). On the other 
hand, many burrowing animals bury organic material and bring mineral 
soil to the surface. The digger wasps add much to the sand by burying 
many insects for their young. Earthworms contribute to soil forma- 
tion (30) . Cowles states further on the authority of Transeau (i 2 2) that 
humus accumulation alters soil aeration. It follows that the atmosphere 
available to subterranean animals differs in different soils. 

III. Atmosphere 

Animals living fully exposed to the atmosphere are usually those most 
dependent upon the various physical factors of the air, viz., light, 
temperature, pressure, humidity, currents, electrical conditions, etc. 

I. LIGHT 

Animals are either positive or negative to the actinic rays of the 
spectrum (45, 123). Considerable work has been done by plant 
ecologists, on the measurement of light with photographic papers, but its 
bearing on plant problems is questioned by some because the nonactinic 
portion of the spectrum is most important in the process of photosyn- 
thesis. It appears that these measurements are of much greater signifi- 
cance for animals than for plants. Zon and Graves (124) have brought 



l6o TERRESTRIAL CONDITIONS 

together the literature and discussed the methods of study (see especially 
several papers by Wiesner). The light in which animals live varies from 
that of the strongest sunlight of mid-day to the darkest recess of soil, etc. 
Many animals show diurnal migration due to changes in light. 

2. TEMPERATURE 

The temperature of the air varies with light (insolation). Cloudy 
summer days are about 4° cooler than sunny days. Cloudy winter days 
are warmer (125, p. 136) than sunny ones. The temperature of the 
lowest strata of air on sunny days varies in some in inverse ratio with the 
distance from the soil, vegetation, etc. The temperature immediately 
above bare soil may be very high in summer (see Table XXXV). 

3. PRESSURE 

According to experimental work by Cohnheim and others (126, 127), 
man is sensitive to variations in atmospheric pressure. Many other 
animals, such as rabbits, dogs, etc., are probably also sensitive. Bird 
movements are often correlated with variation in atmospheric pressure. 
In all cases the pressure, as meteorologically recorded, represents a 
variation in humidity, etc., and relations to pressure alone have been 
but little studied. 

4. HUMIDITY 

Atmospheric humidity (128) is very important to animals and 
determines the sensible temperature and rate of evaporation to a large 
degree (see under "Evaporation," below). 

5. COMPOSITION or THE ATMOSPHERE 

(Table II, p. 59) 
The amount of carbon dioxide varies (125) in different localities but 
is usually greatest near the ground where decomposition is taking place. 
Animals living among decaying organic substances probably live in the 
presence of much more carbon dioxide than animals upon vegetation. 
Carbon dioxide is probably important to animals because of its effect 
upon respiratory activity. Carbon dioxide is believed by some physiolo- 
gists to be a necessary stimulus to the brain to cause all respiratory 
movements. It is further held by some that mountain sickness (asso- 
ciated with high altitude) is due to decreased carbon dioxide pressure. 

6. CURRENTS 

Currents of wind are important in scattering animals and in affecting 
the rate of evaporation from their bodies. Some animals take up 



ATMOSPHERE l6l 

definite positions with reference to wind (anemotaxis) (128a), as for 
example some flies hover in the air in one position with the head toward 
the wind. Some animals, such as the land salamanders, frogs, toads, 
millipedes, spiders, and insects turn away from currents of air because 
of increased evaporation. 

7. ATMOSPHERIC ELECTRICITY (125) 

The effect of atmospheric electricity upon organisms is little known. 
It varies with variations in other conditions of the atmosphere. It will 
probably be found to be important in the life of animals. 

IV. Combinations or Complexes or Factors 

As has already been pointed out (55), the animal environment is a 
combination of moisture, temperature, light, pressure, materials for abode 
and food, all of which factors taken together constitute a complex of 
interdependences. These various factors are so dependent upon one 
another that any change in one usually affects several others. This 
property of environmental complexes is what makes ecology one of the 
most complex of sciences, and experimentation in which the environment 
is kept normal except for one factor, an ideal rarely realized in practice, 
even under the best conditions. 

The efforts of ecologists, geographers, and climatologists have long 
been directed toward the finding of a method of measuring the environ- 
ment which shall include a number of the most important environ- 
mental factors. De Candolle undertook to base the efficiency of a 
climate, for supporting plants, upon the mean daily temperatures above 
6° C, this temperature being taken as the starting-point of plant activity. 
Merriam has followed this lead and calculated total temperatures for 
many places in North America and made maps and zones based upon 
such totals. This system, however, has been rejected by botanists and 
plant ecologists on account of much evidence, both experimental and 
observational, which is quite out of accord with this view. The scheme 
has not been generally accepted by zoologists outside of the United States 
Biological Survey. There is practically no evidence of an experimental 
sort for the application of such a scheme to animals. Relative humidity 
has been suggested as an important index (128) but does not properly 
express the influence of atmospheric humidity upon the animal body 
(125, p. 53). The saturation deficit has also been suggested but does 
not take temperature into account. 



l62 TERRESTRIAL CONDITIONS 

I. EVAPORATION 

"The total effect of air temperature, pressure, relative humidity, 
and average wind velocity upon a free water surface in the shade or in 
the sun is expressed by the amount of water evaporated" (125, p. 72). 
Since temperature in the season without frost is directly due to the sun's 
rays, light is in part included. In our latitude, clouds in summer slightly 
decrease the air temperature (125, p. 72). In winter, however, the 
temperature of cloudy days is higher. The strongest light is usually 
associated with the greatest evaporation. Yapp (129) found that the 
rate of evaporation was directly correlated with temperature and illumi- 
nation, but most closely correlated with relative humidity. From the 
standpoint of including many factors, the evaporating power of the air is 
by far the most inclusive and is therefore by far the best index of physical 
conditions surrounding animals wholly or partly exposed to the atmos- 
phere. It is not, however, to be expected that it will hold good for all the 
factors under all climatic conditions, and for this reason, records of light, 
temperature, pressure, carbon dioxide, etc., should be made. 

The data are usually obtained by using a porous cup atmometer. 
Evaporation from the atmometer is more nearly like that from an organ- 
ism than is evaporation from any other device; it was devised by 
Livingston (130). "It consists of a hollow cup of porous clay 12.5 cm. 
high, with an internal diameter of 2 . 5 cm. and a thickness of wall of about 
3 mm. It is filled with pure water and connected by means of glass 
tubing to a reservoir usually consisting of a wide-mouthed glass bottle of 
one-half liter capacity. The water, passing through the porous walls, 
evaporates from the surface, the loss being constantly replaced from the 
supply within the reservoir. Readings are made by refilling the reservoir 
from a graduated burette to a certain mark scratched upon its neck. 
For convenience in handling, a portion of the base of the cup is coated 
with some impervious substance and, before being used in the field, the 
instrument is standardized by comparing its loss of water with that from 
a free water surface of 45 sq. cm. exposed under uniform conditions. As 
a further check against error this standardization is repeated at intervals 
of six to eight weeks throughout the season" (Fuller, 131). In Fuller's 
work, the bottles were arranged so that the evaporating surface of the 
instrument was 20-25 cm. above the surface of the soil. 

a) Effect of evaporation upon animals. — In the case of man some 
observations have been made. According to Pettenkoffer and Voit (Me 
125), an adult man eliminates 900 gms. of water from his skin and lungs 



EVAPORATION 163 

daily. Of this amount 60 per cent or 540 gms. come from the skin alone 
and changes in relative humidity of only i per cent cause perceptible 
changes in the amount of evaporation from the skin. If evaporation 
from the skin and lungs is diminished, the amount of urine is increased, 
as in many cases are also the secretions of the intestines. Sudden 
changes in humidity make themselves felt in sudden increased or 
decreased blood pressure. The less dilute blood of dry climates operates 
as a stimulant and increases the functions of the nervous system. The 
consequences are excitement and sleeplessness (125, pp. 56-57). 

Little has been done on the physiological effect of evaporation or 
desiccation upon cold-blooded animals. Various writers have found a 
loss of water associated with hibernation. Greeley (132) obtained the 
same results with desiccation as with freezing (132; 133; 51, pp. 
182-88). The reactions of animals to evaporation gradients have been 
studied by the writer (134). A high rate of evaporation is advanta- 
geous to some animals and decidedly detrimental to others. Animals 
inhabiting dense woods turn back when they encounter air with a high 
evaporating power. This is true of frogs, salamanders, insects, and 
millipedes. The frogs and salamanders die in an hour or more in an 
atmosphere of high evaporation power but centipedes and ground beetles 
and other heavily armored animals do not die for many hours or even 
days though they react negatively to the dry air when they encounter 
it in a gradient. Animals from hot, dry, sand areas usually select air of 
high evaporating power and die in air of high evaporating power only 
after very long exposure. The results of a long series of experiments 
may be summarized as follows: (i) the animals studied react to air of 
a given high rate of evaporation whether the evaporation is due to 
moisture, temperature, or rate of movement; (2) the sign and degree 
of reaction to the given rate of evaporation are in accord with the com- 
parative rates of evaporation in the habitats from which the animals 
were collected; (3) the animals of a given habitat are in general agree- 
ment in the matter of sign and degree of reaction ; the minor differences 
which occur are related to vertical conditions (see below) and kind of 
integument; (4) there is a rough agreement between survival time in air 
of high evaporating power, and kind of integument, but no agreement 
between survival time and habitat when a number of members of a com- 
munity are taken together. The relation of warm-blooded animals to 
rate of evaporation has been sufficiently studied so that, when it is 
taken with the work on cold-blooded animals, we are warranted in con- 



164 



TERRESTRIAL CONDITIONS 



eluding that the evaporating power of the air is probably the best index 
of environmental conditions of land animals. 

b) Evaporation in different habitats. — The evaporating power of the 
air varies in different situations (Fig. 115). There are great differences 
between open prairies and closed forests. Shimek (135) found that the 
evaporation in the undisturbed groves in Eastern Iowa during July and 
August was very much less than that in the prairies adjoining. From 
the free surfaces of pans set in the ground so that the water which 
they contained was level with the surface of the soil, the evaporation 
of the groves was about 27 per cent of that of the prairie; with 
cup evaporimeters about 37 per cent, and with Piche evaporimeters 

Per cent, of standard ^ 

1. Salt marsh, outer margin... 

2. Open gravel slide 

3. Carnegie garden, standard .. . 

4. Upper beach 

5. Salt marsh, inner margin 

6. Garden, high level > . . 

7. Gravel slide, partly invaded. 

8. Open forest 

9. Fresh-water marsh 

10. Typical mesophytic forest . . . 

11. Ravine forest 

12. Swamp forest 

Fig. 115. — Showing the comparative evaporation rates in the ground stratum of 
several animal habitats on Long Island during July and August (after Transeau, 
courtesy of the Botanical Gazette) . 






20 


40 


60 


80 


100 


120 










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■ 


■ 


■ 




■ 






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^ 


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^ 


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1 










ig 








^ 


^ 


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n^ 


I 










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^ 


gg 


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1 


2 


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about 47 per cent. This is about the same as the difference on Long 
Island between the inner side of Transeau 's salt marsh dominated 
by grasslike plants and his mesophytic forest. Sherff (135) found the 
evaporation in a marsh forest to be a little less than that in the beech- 
maple and from 1.8 to 2.6 times as great as in the lowest stratum of 
marsh. 

c) Vertical differences in evaporating power and other conditions. — The 
evaporating power of the air is usually greater at the higher levels of a 
habitat. 



STRATIFICATION 



l6S 



TABLE XXXVI 

Evaporation from Porous Cup Evaporimeters in Different Strata of a 
Summer Dry Marsh, Cambridgeshire, England, during Three 
Periods between July 9 and September 8, 1907 
(Yapp, 129, p. 299) 



Height above 
Ground 


Ratio of 
Evapora- 
tion 


Temperatxjre 




Mean 
Max. 


Mean 
Min. 


Mean 




5 ft. 6 in. to 4 ft. 6 in. . 
2 ft. 2 in 


100.00 

32.8 

6.6 


22.1 
23.0 
18.0 
12.7 


6.6 

71 
II. 2 


16. s 

14. 1 

II. 8 


Well above vegetation 

A little above the mid-height 


c in 


Soil 









Table XXXVI shows marked differences in the rate of evaporation 
and considerable differences in temperature at the different levels, both 
due largely to vegetation. Differences in light are also to be expected. 
Sherff (136, p. 420) has found conditions similar to the above by a two 
months' study of evaporation on Skokie Marsh near Chicago. The 
evaporation there was three times as great at a height of 1.95 m. as at 
the surface of the soil in among the plants of Phragmites. Mr. Harvey 
has secured similar (unpublished) results on the prairie at Chicago 
Lawn, Chicago, also Mr. Fuller, in the beech woods. 

Division into strata: Plant and animal habitats are commonly 
divided into strata as shown below. 



Plant (12) after Warming 
I. No such stratum recognized. 



2. Ground stratum made up of algae, 
mosses, immediately above the sur- 
face of the ground. 

3. Field stratum; grasses and herbs. 

4. Shrub stratum; formed of shrubs 
taller than the herbaceous vege- 
tation. 

V Tree stratum. 



Animal 

1. Sub-aqueous stratum made up of 
animals requiring water during 
their active reproductive stages. 

10. Subterranean stratum made up 
of animals or stages in the life 
histories of animals which inhabit 
the ground, especially during the 
breeding season. 

2. Ground stratum made up of ani- 
mals or early stages in the life his- 
tories of animals, as i. 

3. Field stratum; the inhabitants of 
the herbaceous vegetation on land. 

4. Shrub stratum; inhabitants of 
shrubs. 

5. Tree stratum; inhabitants of trees. 



l66 TERRESTRIAL CONDITIONS 

V. Quantity of Life on Land (137) 

The quantity of life on land has been but little studied. While it is 
evident that some habitats have more animals than others, we have no 
exact data. As a rule the number of species is small in pioneer situations. 
While the number of individuals in some one or two species may be large, 
the grand total is probably not so large as in later stages. In forest 
development it appears from naturalistic observations that the number 
of both species and total number of individuals increases with age up 
to the oak-hickory stage, the maximum being in the oak-hickory stage. 
The beech and maple forest is qualitatively and quantitatively poor in 
animals. Felt (137) records pest species on the trees of the white-oak, 
red-oak, hickory forest as follows: Oak in general, 157 ; red oak, 12 ; white 
oak, 31; hickory, 30; wild cherry, 38; hazel, 33; total 401. He records 
pests on trees of beech and maple forest as follows: beech, 92; sugar 
maple, 19; pawpaw, 5; total, 116. 

1. FOOD SUPPLY 

The food supply of land animals is in part dependent upon soil. All 
the chief principles governing the elementary food substance of plants 
and animals in water are given on pp. 65-68. Since all these processes 
are dependent upon water (as a solvent) and since soils at all times con- 
tain some water (116), the reader will easily apply most of the principles 
there stated to the soil problem. There is probably no kind of organic 
matter found that is not food for some animals. Some require plants 
or their juices, some decayed fruits, some wood, some living animals, 
and some carrion. Each stage of its decay, a dead plant or animal is 
food for some animal. 

Certain animals, usually plant-eaters, reproduce very rapidly and are 
preyed upon by many other animals. Mice, aphids, grasshoppers are 
examples (26). These form small centers about which many of the 
activities of a community rotate. The centers are indicated by the 
convergence of lines in Diagram 6. 

2. EQUILIBRIUM 

The balance in land communities is probably less perfect than in 
aquatic communities even under strictly primeval conditions. This is 
due to the fact that there are many small (feeding) groups of organisms 
centering around each of several rapidly reproducing groups such as 
aphids, mice, and grasshoppers. It is accordingly probably possible for 
a land community to be out of adjustment in some particular comer 



EQUILIBRIUM 



167 



without the maladjustment being felt as far as in an aquatic com- 
munity of corresponding magnitude. 

To illustrate the character of land communities in the matter of food 
supply and equilibrium we have chosen a number of prairie animals and 
constructed them into an arbitrary community. This community is 
graphically represented in Diagram 6. The arrows point from the 
animal eaten to the animal doing the devouring, many such relations 
being shown on the basis of actual published records. 




Diagram 6. — Showing the food relations of land animals. Circles and ellipses 
inclose groups of organisms which are commonly eaten by the same animals, and 
groups eating similar food. Arrows point from the animals eaten to those doing the 
eating. For explanation see text. 



From the diagram we note that wolves destroy the bison. If for any 
reason the wolves increased, they would destroy so many bison that the 
bison would decrease because wolves were abundant. The greater 
destruction of mice in summer by the numerous wolves would cause a 
decrease of mice. Finally, wolves would decrease because of lack of big 
game in winter and mice in summer. This would give the bison and 
mice an opportunity to recover their former number and the whole 
chain of changes would be duplicated and a general equilibrium be 



1 68 TERRESTRIAL CONDITIONS 

re-established. The decrease of mice just noted might, however, cause 
the coyote to eat more ground squirrels and thus cause an increase of 
insects because of the removal of the ground squirrel as a check upon 
their numbers. The numerous checks upon the numbers of insects 
would tend to prevent their increasing greatly, but would no doubt 
affect the greater part of the community. The reader will be able to 




A B C D E F 

Diagram 7. — Representing the food relations of the animals of a land community. 
The circles represent life histories which come into contact or overlap at the point 
where one species feeds upon another. The vertical shafts represent the animals 
which feed upon the vegetation (herbivora and phytophaga). The extent to which 
the shaft penetrates the community indicates its importance as food of the forms 
whose life histories are represented. The letters refer to the vertical lines (shafts) 
above them. These lines (shafts) represent the various central groups of Diagram 6 
and other comparable groups as follows: A, large herbivores such as the bison; 
B, the mice, rats, squirrels, and rabbits; C, vegetation-eating birds; D, boring insects 
secured by the woodpeckers; E, the large plant-eating insects; F, the small soft- 
bodied insects such as aphids, scales, etc. The animals represented by the shafts are, 
figuratively speaking, the propellors which keep the life histories shown above them, 
turning. 

trace out many such possible fluctuations and equilibrations. The 
number of possibilities is great even in an arbitrary community, though 
much greater in an actual one. 

Diagram 7 is a graphic representation of the relations of life his- 
tories in land communities to elementary food substances. The number 
of plant-feeders which serve to lock the inorganic substances to the main 
part of the community is far greater than in aquatic communities. 



CHAPTER X 

ANIMAL COMMUNITIES OF THE TENSION LINES BETWEEN LAND 

AND WATER 

I. Introduction 

Margins of bodies of water, swamps and marshes, and temporary 
ponds are on the border-line between land and water. Swamps and 
marshes are areas occupied by plants whose stems, leaves, and blossoms 
are in the air and whose roots are in the water or very moist soil, 
throughout the year. Areas covered by grassUke plants are commonly 
called marshes, while those covered by trees are called swamps. 
Swamps and marshes usually contain water the year round and are 
commonly either directly connected with some permanent body of water 
or are fed by springs. Others are dry in summer, and possess an active 
aquatic fauna only in spring and after heavy rains. Our area, being in 
a region of glaciation, represents a portion of one of the great marsh areas 
of the world. Geologically speaking, however, these features represent 
the positions of lakes and serve to show us the fate of our small lakes 
and ponds. Classification of these communities is difficult, but they 
may be divided into temporary and permanent swamps and marshes 
and into margins of lakes, ponds, and rivers. 

II. Communities 

I. permanent water, swamp, and marsh communities 
a) Lake-margin marsh sub-formation (senescent pond, or emerging 
vegetation pond association) (Stations 30, 30a, 31). — About the margins 
of lakes and ponds there is often a girdle of bulrushes and cattails (Fig. 
116) which has a characteristic animal community. The sub-aquatic 
stratum is made up of pond animals and has been considered already in 
chap. viii. There are a few characteristic animals which live chiefly 
above the water. The diving spider (Dolomedes sexpunctatus) (Fig. 95) 
crawls about on the marsh vegetation and dives beneath the water for 
prey. The long slender spider (Tetragnatha laboriosa) is common among 
the bulrushes (138). At the base of the rushes and sometimes crawling 
near the top is the snail {Succinea retusa) (91). Common frogs (Rana 
pipiens and clamata Dan.) (Fig. 116) and the cricket-frog (Acris gryllus) 
hop about in the water (139). 

169 



1 70 



WET GROUND COMMUNITIES 



There are also a number of insects which live upon the vegetation 
and never go into the water. These are the blue and yellow moth 
(Scepsis fulvicollis), which is most characteristic, flies which breed in the 
water, such as horseflies (Tabanidae) (140), Tetanocera, etc., also midges, 
mosquitoes, dragon-flies, damsel-flies, May-flies, etc. These are asso- 
ciated with grasshoppers, such as Stenohothrus, Xiphidium, and various 










^ 


■? 




M 




1 


{^^^ 




m^ 



Permanent Water Marsh and Its Inhabitants 
Fig. 116. — General view of an open bulrush marsh at Wolf Lake. 
Fig. 117. — Similar but closer view of a marsh at Nippersink Lake, showing the 

yellow-headed blackbird (Xanthocephalus xanthocephalus Bonap.) perched on the 

bulrushes. Photo by T. C. Stephens. 



bugs and beetles which belong to drier places but which alight on the 
vegetation above the water. These will be discussed in connection with 
low prairie communities. 

The birds deserve especial attention (108, 141). The pied billed 
grebe, the black tern, and coot are especially aquatic. The grebe 
builds a nest from decayed floating rushes; its bottom is usually wet and 
the eggs commonly lie in moisture. The black tern builds a nest of 



SWAMP COMMUNITIES 



171 



weeds and trash similarly situated; the coot is less aquatic. The yellow- 
head blackbird (Fig. 117), mallard, pintail, American bittern, the least 
bittern (Fig. 118), the Florida gallinule (Fig. 119), the long-billed marsh 
wren, and sometimes the Virginia, sora, and king rails, and the red- 
winged blackbird nest in such situations. These birds build nests, 
either woven from grasses or in the form of crude piles of dead vegetation, 
each species having its characteristic method. 

The muskrat breeds here and builds a nest from bulrushes (Fig. 82, 




Pekm.\nent Water Marsh and Its Inhabitants 

Fig. h8. — Nest cf the least bittern {Ardella exilis Gmel.) in a marsh at Nipper- 
sink Lake. Photo by T. C. Stephens. 

Fig. 119. — ^Nest of tha Florida gallinule (Gallinula galeata Licht) in a marsh at 
Nippersink Lake. Photo by T. C. Stephens. 

p. 131). The mink likewise is found in this kind of situation (22, 142, 
143). The grassy outer edges of such ponds are the favorite breeding- 
places of frogs (Rana clamata) which stick their eggs to grass. Points 
about such lakes, especially where there are shrubs and willows, are the 
favorite haunts of the bullfrog {Rana catesheiana Shaw) (Fig. 117). 

h) Spring-fed marsh sub-formations (Figs. 120-22) (Stations 10, 51). — 
These are very similar to the marshes which adjoin bodies of water, 



172 



WET GROUND COMMUNITIES 



but the water of such marshes, however, gets very warm in summer, 
while the spring-fed marsh water is usually cool. It is the subaquatic 
stratum which differs most. 

One of our best examples of spring-fed marsh is at Cary, 111. (Fig. 
120). This contains watercress, which is usually associated with springs. 
The most characteristic animals are the flatworms or planarians. Pla- 
naria dorotocephala (Fig. 121) is common on the under sides of leaves, etc. ; 




Spring Marsh and Inhabitants 
Fig. 120. — A spring marsh at Gary, 111. 

Fig. 121. — Planaria dorotocephala; i^ times natural size (original). 
Fig. 122. — ^The brook amphipod (Gammarus fasciatus); twice natural size. 



if one puts a piece of meat into the water it will be covered with worms 
within a short time. The worms follow the diffusing meet juices, often 
passing through the direct sunlight, which they usually avoid. When 
they reach the piece of meat they crawl to the under side. 

Associated with this planarian is Dendrocoelum (144), a larger, light- 
colored species, which does not come to the meat but is found with the 
former, under boards, chips, leaves of plants, etc. The brook amphipod 
{Gammarus fasciatus) (Fig. 122) occurs here also. The animals of the 



TEMPORARY POND COMMUNITIES 173 

vegetation above the water including the birds are about the same as 
in the preceding sub-formations. 

Permanent and temporary swamps are covered with trees. The 
most important permanent swamps are the tamarack swamps. The 
aquatic phase of these will be discussed in connection with the tamarack 
swamp itself (p. 193). Temporary swamps will be discussed under the 
head of temporary forest ponds. 

2. TEMPORARY POND OR TEMPORARY SWAMP AND MARSH 
FORMATIONS 

The situations known as temporary ponds, temporary marshes or 
swamps, or summer dry ponds, are common about Chicago and usually 
contain water in early spring, drying before the first of June. At some 
points at the south end of Lake Michigan much sand has been removed 
for commercial purposes and frequently the workmen remove it to points 
below the ground- water level of the spring months and accordingly make 
temporary ponds which have pure white sand bottoms. A few of these 
have been studied, one when it was one year old, another when about 
twelve years old. These were compared with ponds of the horizontal 
series which are much older. 

a) Bare-bottom association. — Twelve-months pond association (Sta- 
tion 40; Table XXXVII): In April, 1910, we found this pond full of 
filamentous algae, and containing rotifers, copepods, and ostracods, the 
eggs of all of which will probably withstand drying and may have 
blown into the pond during the preceding dry seasons. There was a 
single full-grown snail (Physa gyrina), a small individual (probably 
Physa heterostropha) , and a small long snail, Lymnaea (probably exigua). 
These snails may have been carried into the pond, from other ponds a 
few rods away, on the feet of turtles or frogs. 

Twelve-year-old pond association (Station 40; Table XXXVII) : As 
such a pond as we have just described grows older, the algae continue 
and the reed (Juncus balticus) comes in, together with some sedgelike 
plants. In such ponds the number of species is usually greater than 
at an earlier period. 

In addition to the species found in the twelve-months pond, we 
obtained water-beetles, which are, however, not particularly signifi- 
cant because they may occur in rain pools. Cladocera, the flat snails 
{Planorbis sp.), and the nymphs of damsel-flies and dragon-flies are 
also found. The difference between this pond and the preceding one 
is not great. Indeed, it is only when the bottom of the pond becomes 



174 WET GROUND COMMUNITIES 

covered with sedges that we find marked differences in the ponds of 
different ages. 

h) Vegetation choked temporary pond association (Stations 41, 42, 43; 
Table XXXVII). — Sedges soon take possession of the bottom of such a 
pond as we have been discussing. Just how long a time is required is not 
known, though the pond which we are about to discuss is probably 
several hundred years old. Here we find nearly all the groups men- 
tioned as occurring in the younger ponds, but also certain ecological 
types which are characteristic of sedge-bottomed ponds. Most notable 
is the small green, flat, cigar-shaped worm {Vortex viridis) which usually 
occurs in numbers, and a small brown species of Mesostoma similar 
in form but brown in color. With them are often small larvae of 
dytiscid beetles (species unknown), caddis- worms {Phryganeidae) with 
cases made from pieces of grass (their relation to those in permanent 
ponds is not known), and the snail {Lymnaea modicella). 

As such a pond grows older the sedge becomes thicker and other 
plants make their appearance. What is known as low prairie develops. 
At such a stage the small ponds like those we have been describing 
usually become partially filled and so never contain the best development 
of the older temporary pond community. We accordingly turn to the 
later history of the ponds discussed in the preceding chapters, which 
represent the best development of the temporary pond communities. 

In a forest climate when ponds are filled and drained they are 
occupied by forest. In the steppe climate they are occupied by steppe 
or prairie. In the forest border area, where our studies have been 
carried on, some ponds when filled are occupied by prairies, others by 
forest. Dr. Cowles is of the opinion that ponds with gently sloping 
sides and bottoms become covered with prairie, while those with steep 
slopes become covered with forest (Fig. 123). 

As ponds, such as we have discussed in the preceding chapter, 
become ecologically old, they dry in dry seasons. They usually become 
occupied by cattails, equisetum, or other grasslike plants. The red- 
winged blackbird (Fig. 124) occasionally nests in them. At such a 
stage the isopods (Asellus communis and Mancasellus danielsi), amphi- 
pods (Eucrangonyx) (Fig. 113), and snails {Lymnaea reflexa) (Fig. 125; 
compare with Fig. 104, p. 149) are common. The fringe-legged mosquito 
(145) and the common marsh mosquito (Fig. 126) breed in such situations 
while the crayfishes and various of the old-pond species continue. 

When such a stage is reached, it is only a step to the typical tempo- 
rary pond. If the ground- water level is lowered, as is the case in many 



TEMPORARY POND COMMUNITIES 



175 




Semi-temporary Pond or Marsh and Inhabitants 

Fig. 123. — General view of Pond 93, which is occupied by Sagittaria and grass- 
like plants. 

Fig. 124. — Side view of a red-winged blackbird's nest. Photo by T. C. Stephens. 

Fig. 1240. — The same from above. 

Fig. 125. — A temporary pond form of the snail {Lymnaea reflexa)', natural size. 



176 



WET GROUND COMMUNITIES 



of the ponds south of Lake Michigan, such ponds usually become grassy 
in the middle and often typical temporary prairie ponds. Here we find 
the green flatworm (Vortex), vernal planarians (Planaria velata), great 




Fig. 126. — The common marsh mosquito (Anopheles punctipennis SayJ; much 
enlarged (from Williston after Smith). The details are such as to enable one to 
recognize this species of mosquito: (i) adult female; (2) her palpus; (3) her genitalia; 
(4) part of a wing- vein showing scales; (5) anterior, and (6) middle claws of the male. 



numbers of Entomostraca, belonging to all orders. Of the last there are 
many very large cladocerans, the copepods (146) {Cyclops viridis 
americanus )(Fig. 127), the red copepod {Diaptomus stagnalis) (Fig. 128), 



TEMPORARY POND COMMUNITIES 



177 



the ostraccd (Cyprois marginata )(i47) (Fig. 129), and the fairy shrimp 
{Eubranchipus) (148) (Fig. 130), all of which are characteristic of tempo- 
rary ponds. Red mites (Fig. 131) are also common (149). 

Professor Child (unpublished) has noted that the distribution each 
spring of Eubranchipus and of other temporary pond species is modified 




Temporary Grassy Pond Animals 

Fig. 127. — A temporary pond copepod {Cyclops viriiis americanus Marsh); 35 
times natural size (after Herrick and Turner) . 

Fig. 128. — ^The red copepod {Diaptomus stagnalis) from temporary pond; 12 
times natural size, left antenna omitted (after Herrick and Turner). 

Fig. 129 — The temporary pond ostracod {Cyprois marginata); 35 times natural 
size (after Sharp) . 

Fig. 130. — The fairy shrimp {Eubranchipus); 3 times natural size. 

Fig. 131. — The red mite {Hydrachna sp.); 10 times natural size. 



by the rainfall of the preceding season. When the rainfall of the pre- 
ceding season has been great, the temporary pond species are found only 
in the smallest and highest (above ground-water) ponds such as would 



178 



WET GROUND COMMUNITIES 



develop in the place of one of the small ones with sandy bottom. Follow- 
ing dry seasons the temporary pond species are found in ponds which do 
not usually dry in summer, but which were dry the preceding summer. 
It has been shown that the eggs of Eubranchipus must be dried and 




Fig. 132. — The little smoky mosquito (Aedes fusca O. S.); much enlarged (from 
Williston after Smith): (i) adiilt female; (2) her palpus; (3) palpus of the male; 
(4) anterior; (5) middle, and (6) posterior claws of the male. 



frozen before they will hatch. The relation of their distribution, follow- 
ing the seasons of different rainfall, suggests that some definite degree 
of drying must be attained to insure hatching as well as that the eggs 
are probably blown about by wind. One autumn, about 1900, there was 



TEMPORARY POND COMMUNITIES 



179 



early freezing and cold weather followed by warm weather of a very 
springlike character in December. Professor Child observed that the 
Eubranchipus hatched during this period of warm weather. Cold weather 
came on soon after and most of those that had hatched died before 
reaching sexual maturity, and for several years after the species was 
very scarce in the vicinity of Chicago. Eubranchipus is found only in 
grassy ponds, possibly because the forested ponds do not dry sufficiently 
in summer. We have found it on one occasion in woods, but this was 




The Bare Sand Water Margin and Inhabitants 
Fig. 133. — Margin of Lake Michigan at Buffington. 

Fig. 134. — The beach tiger-beetle (Cicindela hirlicollis); i| times natural size. 
Fig. 135. — The beach ground beetle {Bembidium carinula) ; i\ times natural size. 

in flood-plain pools following an early spring flood and might have been 
due to the washing-in of eggs or young. 

c) Forest temporary pond sub-formation (association) (Station 50; 
Table XXXVII).— These are characterized by the absence of both 
Diaptomus and Eubranchipus. The Entomostraca are chiefly ostracods, 
such as Cyprois marginata, which occurs in grassy ponds. Vortex, mos- 
quito larvae, the little bivalve (Musculium), small earthworms (Lum- 
briculus), and the larvae of a beetle (Dascyllidae) are also very common. 



i8o 



WET GROUND COMMUNITIES 



The amphipods and sowbugs of the earlier stages are still present. This 
is the breeding-place of such mosquitoes as the little smoky mosquito 
(Aedes fuscus) (Fig. 132, p. 178) (145, 99c). 

3. COMMUNITIES OF MARGINS OF BODIES OF WATER 

There is always a narrow area along the margins of bodies of water 
which is difficult to classify as water or as land. The association of 
this area is the one with which we now have to deal. 

Along the margins of young ponds and lakes is an area which is 
characterized by being made up of wet sand or mud which is sub- 
merged at high water and moist at 
other times. 

a) Association of the terrigenous mar- 
gins of large lakes (Fig. 133) (Stations 
57, 58; Table XXXVIII).— Here we 
find the springtails the simplest in- 
sects, the shore bugs (150), Saldidae, 
especially Salda humilis Say, a large 
number of tiger-beetles (151) (Cicin- 
dela hirticollis) (Fig. 134) (C. cupras- 
cens), together with numerous small 
flies. 

The ground beetle (Bembidium 
carinula) (Fig. 135) and numerous 
scavengers are common because the 
beach is often strewn with dead ani- 
mals which have floated ashore. The 
relations of the drift to other com- 
munities will be discussed in the 
chapter on dry forests. The spotted 
sandpiper feeds here, and with the piping plover often breeds not far 
from the water's edge. Under conditions of rapid recession of the lake 
such a margin is separated from the wave-action. It is then rapidly 
transformed into the next association. 

h) Association of the terrigenous margins of pofids and small lakes 
(Stations 30, 40; Table XXXIX). — This association differs from that of 
the large lake in that the scavengers are absent and the animals much 
less active, not moving about so rapidly. Here we find springtails, 
Saldidae of another species, and the toadbug (Gelastocoris oculatus) (150) 
(Fig. 136), which is colored like the ground and is found hopping about 




Fig. 136. — ^The bare pond and river- 
margin toadbug {Gelastocoris oculatus) ; 
greatly enlarged (after Lugger). 



WATER MARGIN COMMUNITIES 



l8l 



close to the water. The tiger-beetle of the Lake Michigan shore is dis- 
placed by that of another (Cicindela repanda) which is less active. With 
these is the hooded grouse locust {Paratetlix cucullatus) (Fig. 137) (40, 
p, 419). The small semiaquatic snail (Lymnaea modicella) is frequently- 
present in numbers. 

The nests of the spotted sandpiper (108, 141) and the yellowlegs are 
found here, and the birds no doubt feed upon the invertebrates present 
on the margins of the ponds and of the shallow water. 

c) Association of sedge margins of ponds and small lakes (Stations 
32-34; Tables XL, XLI).— As time goes on, the sandy margin is 
captured by sedges which are scattered at first, so that the animals just 
discussed continue for a time among them (Figs. 138, 139). Finally, 
however, the ground becomes sodded over 
with sedges and a low prairie animal commu- 
nity comes in, and the bare ground animals 
disappear. In the case of ponds which are 
to develop into forest this stage is found 
only along the young ones. The sedges are 
soon displaced by shrubs and the sedge 
communities give way to shrub. 

d) Associations of shrub margins of ponds 
and small lakes (Fig. 140) (Stations 34, 37, 
44; Tables XLI, XLII).— Mr. Allee has 
verified my observations to the effect that 
the aquatic part of this formation is almost 
entirely barren; however, in summer we get 
the short-winged and armed grouse locust (Tettigidea armata Morse, 
and parvipennis Harr.) (40) and the slimy salamander {Plethodon 
glutinosus) (152) (Fig. 141). Of the birds associated with the water 
we have here the wood-duck and the green heron. 

4. MARGINS OF RIVERS 

(Station 29) 
Here the sandy margin is similar to that of the ponds and lake. 
Along the Fox River we find the mole cricket (40) which burrows into 
the sand. Mud margins are rather barren except for occasional beetles. 
The margins of rivers which are grassy or marshy are like those of ponds 
and lakes. The margins of the Calumet and lower Deep rivers are 
covered with marsh plants and saturated with water in spring. They 
are the nesting-places of the long-billed marsh wren (Figs. 142, 143) and 
many other marsh birds (108, 153). 




Fig. 137. — ^Hooded grouse 
locust {Paratetlix cuctdlatus) 
(after Lugger). 



WET GROUND COMMUNITIES 




139 



Fig. 138. — Prairie-like stage of a pond margin. 
Habitat of Cictndela Iranquebarica in the pine 
zone of the ridges at the south end of Lake 
Michigan. The dark portion in the foreground 
is the shadow of a tree. At the left is the 
cattail zone of the depression; between a and 
b, the sedge zone; between b and c the zone of 
high-depression plants. The white blossoms 
here are those of Parnassia caroliniana; their 
distribution, September, 1906, corresponds ap- 
proximately to the distribution of the larvae of 
C. Iranquebarica, which arose from eggs laid in 
May and June, 1905. The portion to the right 
and above c represents the higher portion of the 
ridge and the habitat of C. scutellaris. Reprinted 
from the Journal of Morphology. 

Fig. 139. — The upper part of the burrow of 
C. Iranquebarica, pupal cell shown by dotted 
line; ^ natural size. Reprinted from the Journal 
of Morphology. 



WATER MARGIN COMMUNITIES 
III. General Discussion 



183 



The areas which we have been discussing in this chapter are the 
tension lines between the land and the water. It is in such areas that 
ecologists have learned most about succession and about the tendencies 




Fig. 140. — Pond 95, showing the death of the pond by the growth of buttonbush. 
Fig. 141. — The shiny salamander {Plethodon glutinosus); about twice natural 
size (after Fowler). 



and processes in animal formations and associations. In this chapter 
we first considered th^ marshes which border the lakes and ponds about 
Chicago. Dr. Cowles and others have pointed out that lakes and ponds 
are filled by organic debris and that bulrushes invade from the shore and 
''capture" the ponds and lakes. As the bulrushes and other plants 



1 84 



WET GROUND COMMUNITIES 



invade, the girdle of marsh which is the nesting site of the birds men- 
tioned moves farther and farther toward the center of the pond or lake, 
the former positions being occupied by shrubs, such as buttonbush or 
willow, or in some cases by prairie. Such a situation is in unstable 
equilibrium. 

Turning to the margins of ponds, lakes, and rivers, we note that 
at the beginning we often have the bare sand. This is first occupied 




Fig. 142. — The long-billed marsh wren's nest. The nest unopened. 
Fig. 143. — The nest torn open showing the eggs. 

by reeds and sedges, and finally by shrubs. It is this reed and sedge 
group, or the buttonbush, that invades the swamp as it fills with bul- 
rushes and cattails. We note accordingly that the vegetation which 
appears on the shore invades the pond as it fills. The last stage of 
a pond is either a buttonbush swamp or a low prairie which we shall 
discuss in later chapters. 



WET GROUND ANIMALS 



i8S 



TABLE XXXVII 

Temporary Ponds of Different Ages 
The numbers standing at the heads of the columns where months or years are 
not indicated refer to the number of the pond in question when counted from the lake. 
J.P. is a pond south of Jackson Park. 



CoioioN Naue 



Rotifer . . . 
Copepod . . 
Gladoceran . 
Ostracod . . 

Snail 

Snail 



Ground beetle. . . 
Scavenger beetle. 



Small water-bug 

Scavenger beetle . . . 
Water-strider . . . . , 

Water-mite 

Flat snail 

Dragon-fly nymph . 
Toad-shaped bug . . 



Green flatworm .... 
Brown flatworm . . . 
Predaceous beetle . 

Springtail 

Caddis-worm 

Pond snail 

Red copepod 



Fairy shrimp . 



Vernal planarian. 
Amphipod 



Isopod 

Mosquito larva . 
Bivalve 



•Ostracod. 
Ostracod . 



Beetle larva . . . 
Annelid worm 



Scientific Name 



Physa gyrina Say. . . 
Lytnnaea obrussa exigua 

Lea 

Bembidium sp 

Aphodius fitnetarius 

Linn 

Zaitha fluminea Say. . . 

Hydrophilidae 

Gerridae 

Hydrachna sp 

Planorbis 

Enallagma 

Gelastocoris oculatus 

Fabr 

Vortex viridis M. Sch. 

Mesostoma sp 

Dytiscidae 

Collembola 

Neuronia ? sp 

Lytnnaea reflexa Say. . 
Diaptomus stagnalis 

For 

Eubranchipus serratus 

Forbes 

Planaria velata Str. . . . 
Eucrangonyx gracilis 

Sm 

Asellus communis Say. 

Culicidae 

Musculium secure 

Prime 

Cypris fuscata Jurine. . 
Cyprois marginata 

Strauss 

Dascyllidae 

Lumbriculus 

inconstans Smith 



Undifferen- 
tiated 



12 Mo. 12 Yr. 



Prairie 



ss J.P 



For- 
est 



94 



1 86 



WET GROUND COMMUNITIES 



TABLE XXXVIII 

Animals Frequenting the Moist Margin of Lake Michigan 

(Stations 57, 58) 



Common Name 


Scientific Name Month 

1 


Flesh-fly 


Sarcophaga sp 4—9 


Flesh-fly 


Chrysomyia macellaria Fab 4—9 


Flesh-fly 


Cynomyia cadaverina Des a— 


Hister beetle 


Saprinus patruelis Lee 


4-9 

A.—Q 


Ground beetle 


Bembidium carinula Chd 


Tiger -beetle 


Cicindela hirticollis Say 


6-8 


Tiger-beetle 


Cicindela cuprascens Lee 


7-8 









TABLE XXXIX 

Animals Resident on the Margin of a Twelve-Year-Old Artificial Pond and 

OF Wolf Lake (Sandy) 

(Stations 30, 40) 



Common Name 


Scientific Name 


Month 


Ground beetle 


Bembidium variegatum Say 




Snail 


Lymnaea humilis modicella Say 

Gelastocoris oculaius Fabr 


4-9 




4-0 


Tiger-beetle 


Cicindela repanda Dej 


4-0 


Hooded grouse locust 


Paratettix cucuUatus Burm 


4-0 







WET GROUND ANIMALS 



187 



TABLE XL 

Animals Recorded from Sedge-covered Pond Margins 
(Stations 32, 33) 



Common Name 



Scientific Name 



Month 



Snail 

Snail 

Snail 

May-fly 

Toad 

Diving spider 

Spider 

Walking-stick 

Grasshopper nymph . . . . 

Damsel-bug 

Centipede 

Spider 

Long-bodied spider .... 

Spider 

Spider 

Orb-weaving spider. . . . 

Short-tongue bee 

Ant 

Root beetle 

Root beetle 

Spider 

Ambush-bug 

Negro-bug 

Bug 

Red-legged grasshopper . 

Stinkbug 

Ant 

Midge 



Lymnaea hutnilis modicella Say . 

Succinea relusa Lea 

Succinea avara Say 



Bufo lentiginosus Sh 

Dolomedes sexpunclatus Htz 

Pirala insular is Em 

Diapheromera femorata Say 

Acrididae , 

Reduviolus Jems Linn 

Lithobius sp 

Chiracanthium inclusa Htz 

Telragnatha laboriosa Htz 

Tibellus duttoni Htz . 

Eucla catidala Em 

Epeira foliata Koch 

Augochlora confusa Rob 

Ponera coarctata Latr 

Diabroiica 12-punctata Oliv 

Diabrotica vittata Fab 

Dictyna siiblata Htz 

Phyinata fasciata Gray 

Thyreocoris unicolor P.B 

Philaronia bilineata Say 

Melanoplus femur-rubrum DeG. . . 

Cosmopepla carnifex Fab 

Formica fiisca var. subsericea Say . 
Chironomidae 



4-9 
4-9 
4-9 
4-9 
4-9 
4-9 

8-^ 
6-10 

8-9 
4-9 
8-9 
8-9 
8-9 

5 
S-9 
7-8 

9 
8 



i88 



WET GROUND COMMUNITIES 



TABLE XLI 

Animals Recorded from the Margin of Pond 8 (Mixed Sedges and Shrubs) 

BY Mr. B. F. Isely 
(Station 34) 



Common Name 



Scientific Name 



Month 



Lygaeid 

Apple-leaf hopper 

Lacebug 

Jassid 

Dusky plant-bug 

Cranberry lygaeid 

Beetle 

Ground beetle 

Ant-like flower-beetle 

Leaf-beetle 

Mordellid 

Case-bearer 

Strawberry beetle 

Lampyrid 

Lampyrid 

Lampyrid 

Metallic wood-borer 

Dascyllid 

Maia or buck moth 

Short-winged brown grass- 
hopper 

Slender meadow grasshopper . 
Short-winged meadow gr'hop. 

Fly 

Fly 

Fly 

Fly 

Horsefly 

Horsefly 

Syrphus fly 



Cymus angustatus Stal 

Empoasca ntali LeB 

Physatochila plexa Say 

Draeculacephala mollipes Say .... 

Adelphocoris rapidtis Say 

I schnodenms f aliens Say 

Nodonota trislis Oliv 

Anomoglossus pusillus Say 

Stereopalpus mellyi Laf 

Chalepus hornii Sm 

M ordellistena aspersa Mel 

Pachybrachys abdominalis Say. . . . 
Typophorus canellus sellatus Horn 

Lucidota punctata Lee 

Pyradomena borealis Rand 

Lucidota atra Fab 

Pachyscelus laevigatus Say 

Ptilodactyla serricollis Say 

Hemileuca maia Dru 

Stenobothrus curtipennis Harr . . . . 

Xiphidium fasciatum DeG 

Xiphidiutn brevipenne Scud 

Tetanocera umbrarum Lin 

Tetanocera plumosa Loew 

Tetanocera combinata Loew 

Tetanocera saratogensis Fitch .... 

Chrysops aestuans V.W 

Chrysops callidus O.S 

Mesogramma marginata Say 



7-8 

7-8 
7-8 

7-8 
7-8 
7-8 
7-8 
7-8 
7-8 
7-8 
7-8 
6-9 

7 

7 

7 

7 

7 

7 

7-8 
7-v8 
7-8 
7-8 
7-8 
7-8 
7-8 
7-8 
7-8 
7-8 



TABLE XLII 

Animals Recorded from the Willow and Buttonbush. Margins of Ponds 

52 and 93. Records by Allee are Indicated 

(Stations 37, 44) 



Common Name 


Scientific Name 


Month 


Plant-bug 


Adelphocoris rapidus Say (young) 

Cosmopepla carnifex Fabr 


7-8 


Stinkbug 


7-8 


Fulgorid .... 


Atnphiscepa bivittata Say 


7-8 


Jassid 


Parabolocratus viridis Uhler 


8 


Smeared dagger-moth 

Ant 


Acronycta oblinita S and A (Allee).. . . 

Aphaenogaster treatae Forel (Allee) 

Tetanocera sp. (Allee) 


8 
8 


Flv 


8 


Spider . 


Epeira trivittata Key. (Allee) 


8 


Leaf-beetle 


Calligrapha muUipunctata var. bigsby- 
ana Kirby (Allee) 








Leaf -beetle 


Typophorus canellus aterrimus Oliv .... 









CHAPTER XI 

ANIMAL COMMUNITIES OF SWAMP AND FLOOD-PLAIN FORESTS 

I. Introduction 

Swamp forests are those which arise in the areas formerly occupied 
by ponds and lakes and which grow in water or very wet soil. About 
Chicago the many coastal and morainic lakes of earlier periods have been 
filled by organic detritus and more or less completely occupied by trees. 
Often the trees have grown upon floating bogs such as sometimes occur 
about lakes, though sometimes they have sprung up on solid ground and 
compact organic detritus. 

II. Swamp Forest Formations and Associations 

We shall consider these forests genetically: the marsh which often 
appears first, the shrub stage which follows, and finally the forest. 

I. THE elm-ash swamp FOREST COMMUNITIES 

a) The marsh association (Station 52; Table XLI). — One of the best 
examples of this community is at the north end of Wolf Lake, Ind. The 
youngest part is occupied by bulrushes and Hibiscus, and covered in the 
spring by about a foot of water which teems with small crustaceans, 
mosquito larvae, and red water-mites. Lymnaea reflex, usually about 
half the size of the specimens (ic»o) of permanent ponds, and the small 
bivalve {Musculium) are present. As the season advances the water 
dries up and the eggs of the crustaceans and adult mollusks live through 
the dry season on the bottom of the pool. Above the water on the 
Hibiscus are the small Succinea retusa (91, 100), which belong to the 
forest edge and low prairie. 

b) Shrub association (forest edge sub-formation) (Station 52; Table 
LXIII). — Surrounding the central pool which we have described is 
usually a girdle of buttonbush. Here we recognize several strata. The 
subterranean stratum has few inhabitants. We have recorded none. 

The ground stratum is not inhabited by many animals. The wood- 
cock and the northern yellowthroat (108, 153) probably occasionally 
nest here on the ground, possibly also the common shrew (Sorex 
personatus St. Hil.) (142). There is no distinct field stratum, as the 

189 



IQO WET FOREST COMMUNITIES 

thickness of the shrubs prevents the growth of herbaceous vegetation. 
The shrub stratum is the chief habitat. 

The buttonbush is remarkably free from plant-feeding animals. 
Occasionally some of the willow-eaters, such as the larva of the smeared 
dagger-moth, are found on it, but never in any numbers. This stratum 
is the resting-place of many of the insects whose early stages inhabit 
water. When the plants are in blossom, it is visited by many flower- 
frequenting insects, such as the bumblebee (40). 

Mr. Visher has recorded a number of nesting birds in this girdle. 
The wood-duck usually makes its nest here in some hollow tree and lines 
it with feathers; where stumps or rotten trunks are found theprothono- 
tary warbler sometimes nests; Traill's flycatcher {Empidonax trailli 
Aud.) places its nest well up in the branches and leaves of the bushes. 

c) Forest formation (Stations 52 and 53; Table L). — As time goes 
on and the marsh fills with organic detritus, the buttonbush which is 
continually encroaching upon it comes to occupy a position farther in, 
while its former location is taken by the ash, which is the next girdle 
outside. 

The ash is succeeded by the American elm and the bass wood. These 
are frequently considerably mixed with the ash, but the two girdles can 
be distinguished in the Wolf Lake Forest. For convenience we shall 
treat these two girdles (associations) together under the head of the wet 
forest formation. 

The subaqueous and subterranean-ground strata: The subterranean 
portion is inhabited by earthworms. On the higher parts there are 
doubtless other subterranean forms. Where the roots of the grapevine 
are in the drier soil, the vines are infested with the aphid (Phylloxera) 
which makes galls on both roots and leaves. The depressions of these 
forests are filled with water in spring and support temporary pond ani- 
mals such as we have discussed on p. 179. 

In the Wolf Lake woods we noted in the spring of 1910 that the small 
red spiders (Trombidium sp.) were numerous. Centipedes, crane-fly 
larvae, and ground beetles occur under the leaves. Hancock (40, p. 419) 
states that the obscure and Indiana grouse locusts {Tettix obscura Han. 
and Neotettix hancocki Bl.) are found in such forests. Under pieces of 
rotten wood are sometimes found specimens of the small snail (Zonitoides 
arboreus), which is first to appear in forests developing from the button- 
bush swamp stages. On highest ground we get two other snails (Poly- 
gyra monodon and Pyramidula striatella Ant.) (91, 100). In the fallen 
logs we find a considerable number of borers (Parandra brunnea Fabr. 



SWAMP FOREST COMMUNITIES 191 

and others) and under the loosened bark are centipedes (Lithobius), milli- 
pedes (Polydesmus) , and beetle larvae (Pyrochroidae) which are flattened. 

While we have no actual records of mammals in such situations, 
doubtless the varying hare {Lepus americanus Erx.) which frequents 
marshy woods with thickets such as the buttonbush, the common shrew, 
which nests under logs, and the mink {Mustela vison lutreocephalaHarlaii) , 
all have been visitors if not residents in such situations in the past. The 
wood-duck, the woodcock, and prothonotary warbler often nest in such 
woods. 

Field stratum: The field stratum is inhabited by small flies, such 
as crane-flies, midges, and mosquitoes (Chironomidae and Culicidae), 
occasional spiders, such as Theridium frondeum, parasitic hymenoptera 
{Pimpla inquisitor Say, Ichneumon mendax Cress.) and the scorpion-fly 
(Panorpa), which breeds in the ground. 

Shrub stratum: The shrubs consist chiefly of buttonbushes and low- 
hanging grapevines. The vines frequently have conspicuous insect 
galls. One called the grapevine apple gall, because of its shape, is due 
to the larva of a small fly (Cecidomyia vitis-pomum W and R) (137); 
anDther which is a pointed tube on the leaf is due to Cecidomyia viticola. 
Wartlike galls on the under side of the leaves are due to Phylloxera 
vastratrix PL (Fig. 277, p. 273) (150), an aphid which, when introduced 
into France, threatened to destroy the vine industry. These occur only 
on the vines on high ground where the roots, upon which a part of the 
life of the aphids is spent, are out of water. Several grape insects, includ- 
ing the fulgorid bug {Ormenis pruinosa Say), have been taken. 

Tree stratum: The tree stratum of this girdle has not been studied, 
because the study of the tree stratum in general is difficult. The white 
ash is, however, attacked by many insects. Felt (137) and Packard (154) 
record a number. One of the most difficult groups to secure is the 
"borers" of the solid wood or sap wood of trunk and twigs. These are 
chiefly beetle larvae, especially the Cerambycidae (155), or long-horned 
beetles. The larvae of these are legless and only slightly larger at the 
anterior end. Another prominent family is the metallic wood-borers or 
Buprestidae (155). The larvae of these are also legless and may be dis- 
tinguished from the preceding by a broad, flattened enlargement just 
behind the head. The ecology of these two families alone is a subject 
for a work the size of this volume (see 137 and 154). The four-marked 
borer (Eburia quadrigeminata Say) is said to occur on the ash through- 
out Indiana (156). The elm and basswood likewise have many borers, 
some in common with the ash. 



192 WET FOREST COMMUNITIES 

The insects feeding on the leaves are numerous on all the trees. The 
following are common to the three trees mentioned (137): the cater- 
pillars of the hickory tussock-moth, the American dagger-moth, the forest 
tent caterpillar, the white-marked tussock-moth; each has a preference 
for one of the trees. The larvae of several other common moths occur 
on two of the trees, a few are confined to one. Beetle and sawfly larvae 
also attack the leaves. Each tree has its characteristic gall insects and 
galls; for example, on the elm, the coxcomb gall {Colopha ulmicola Fitch), 
on the ash, the midrib gall {Cecidomyia verrucicola O.S.). These are 
believed to be confined to particular tree species. 

According to Wood (21) such forests are the chief haunts of the gray 
squirrel. The green heron is especially likely to nest on the low trees 
of such a forest if they are near water. 

2. OTHER TYPES OF SWAMP FOREST COMMUNITIES 

The swamp forest formation is well developed in the Skokie marsh 
area. We have visited these woods at a point west of Dempster Street, 
Evanston. This was originally characterized by trees very much larger 
than those at Wolf Lake. The soil at Wolf Lake is sand, while that at 
Evanston is clay, which is probably more favorable for trees. However, 
the most important cause of the greater luxuriance is greater age. 
The subterranean stratum has not been studied. 

The ground stratum: Here we find, in addition to those species 
of the temporary ponds at Wolf Lake, a snail (Aplexa hypnorum Linn.) 
which is characteristic of very transient ponds (100). 

On November 27, 1903, the condition of the animals of this stratum 
was noteworthy. In the lower moister parts of the wood we found the 
mollusks, especially Pyramidula alternata, in groups under logs. One of 
these groups contained 1 2 individuals. Under another log was a group 
of about 50 ground beetles (Platynus sp.). Under one small piece of 
bark were found three ground beetles, three rove-beetles, one slug, and 
two snails. Under another, one tetrigid or grouse locust, several ground 
beetles, and a rove-beetle. Under the bark of a log on the above date 
we found the hibernating parasitic hymenoptera (Ichneumon extrematatus 
Cress., galenus Cress, and mendax), also a queen white-faced hornet 
(Vespa maculata), which with its colony builds a large spherical nest 
in a tree in summer. 

Most noticeable of all was a group of several hundred small blue 
chrysomelid beetles (Haltica ignita Illig.). They were under the leaves 
at the base of a tree down the sides of which individuals of the same 



TAMARACK FOREST COMMUNITIES 193 

species were moving. Such groupings are common among hibernating 
insects and are believed to keep the temperature a little higher. Baker 
(100) has studied the wet forest near Shermerville, III. In his Stations 
7-17 the forests are ecologically older. (For birds and moUusks present, 
see 100, p. 468.) 

3. THE TAMARACK SWAMP COMMUNITIES 

(Stations 54, 54a; Tables XLIII-XLV) 

Tamarack swamps develop about deep lakes. Floating plant debris 
supports first water-lilies and later bulrushes and cattails. Upon these 
grow shrubs, such as the leather-leaf and the willows; these make condi- 
tions suitable for the poison sumac and young tamaracks. The semi- 
aquatic plants are thus succeeded by the shrubs and finally by the 
tamarack. 

The aquatic communities have not been studied in a typical tamarack 
lake, but there is no reason to suppose that they differ in any important 
way from the aquatic communities of other old bodies of water. 

a) Floating bog and forest edge association (Tables XLIII, XLIV). — 
The floating bog of cattails and bulrushes is usually full of low places in 
which water is present the year round. Here we find the typical 
animals of semi-temporary ponds, as described on p, 150. The various 
frogs of the marsh probably breed here. Another aquatic habitat of 
some interest is the water-holding leaves of the pitcher-plant (158). 
The pitcher-plant mosquito (Wyeomyia smithii) is known to breed in the 
leaves of pitcher-plants only. These are accompanied by the larvae of 
midges and large numbers of dead insects which crawl into the pitchers 
and cannot get out on account of the presence of many hairs which pro- 
ject inward along the wall of the entrance. 

The surface of the bog is frequented by marsh spiders, insects, and 
frogs, only a few of which belong especially to pre-tamarack bogs. The 
inhabitants of the vegetation (field stratum) are like those on the vege- 
tation over other marshes, belonging chiefly to low prairies. The edge 
of the tamarack woods (Fig. 144) is a characteristic forest margin. 
Except for the presence of some of the tamarack leaf-feeders, such as 
the larch sawfly larva and measuring-worm, it possesses few species 
different from the margins of other marshes (Fig. 145). 

h) Tamarack forest formation (Table XLV). — -Pools: The pools 
within the forest proper contain old-pond animals together with some 
mosquito larvae (such as those of Culex canadensis) which are char- 
acteristic of pools in all moist and mesophytic forests (see 99c). 



194 



WET FOREST COMMUNITIES 




Represejjtatives of the Tamarack Swamp Community 

Fig. 144. — View in the dense vegetation of the tamarack swamp. 

Fig. 145. — Female orb-weaver (Epeira gigas); about natural size. 

Fig. 146. — The brindled locust (Melanoplus pmidulatus) ; natural size. 

Fig. 147. — An eax^'ig {Apterygida actdeala); natural size. 

Fig. 148. — An engraver beetle destroyer {Cleridae, Thanasimns dnbius) ; 3 times 
natural size (from Blatchley after Wolcott) . 

Fig. 149. — The bark of the tamarack, showing the work of the engraver beetle 
{Polygraphus rufipennis) . 

Figs. 150, 150a. — Pickering's tree-frog (Hyla pickeringii); about two-thirds 
natural size (after Fowler). 



TAMARACK FOREST COMMUNITIES 195 

Ground stratum: On the sphagnum, which sometimes occurs in the 
pools, various insects and spiders occur, including, according to Hancock 
(40), two species of sphagnum crickets. On the higher ground numbers 
of typical moist forest animals occur sparingly. Frogs are often numer- 
ous. The common frogs (Rana pipiens and clamata) and the marsh 
tree-frog (Chorophilus nigritus) occur in summer. The wood-frog and 
Pickering's tree-frog {Rana sylvatica and Hyla pickeringii, Fig. 150) are 
regular residents; probably both breed in the pools (139) between the 
hummocks. Farther north the hermit thrush nests on the hummocks 
amid the dense undergrowth. This is also the typical haunt of the 
varying hare (Lepus americanus Erx.) (83, 142, 143), which is white in 
winter and brown m summer; it is common in tamarack swamps farther 
north. The lynx (p. 15) was probably once common near Chicago and 
is most likely to have frequented these swamps. Adams (83, 42) records 
its tracks on the hummocks of the tamarack swamps on Isle Royale in 
Lake Superior. Judged by its tracks it wanders far. It feeds largely 
on hares, the numbers of which fluctuate (inversely) with the numbers of 
lynx. The otter (Lutra canadensis Schr.) and Cooper's lemming mouse 
might be added as probable former residents (143, 21). 

Field stratum: This is confined to hummocks supporting herbaceous 
plants. Insects, spiders (159), etc., are common; some characteristic 
species occur. 

Tree stratum : The brindled grasshopper (Melanoplus punctulatus) 
(Fig. 146) has been found on the low branches of the tamarack and 
deposits its eggs on the bark of the trunk or on stumps. Several other 
insects have been recorded as common on the tamarack, among which 
are a sawfly, an earwig (Fig. 147), a lappet moth, and a woolly aphid, 
but we have not taken all of them. (See 137, II, 838, and I, Plate 18.) 
The tamarack is infested by bark beetles. In the swamp at Mineral 
Springs, Ind., we found one (Folygraphus rufipennis) (137), sometimes 
also Dendroctonus simplex Lee, common under the bark of partially dead 
trees (Fig. 149). The larvae of the clerid beetle {Thanasimus dubius) 
(Fig. 148) (137) occur with the bark beetles and feed upon them. 
The adult of the clerid (137) appears in spring, having wintered over 
as adult or in the late larval or pupal stage. It goes about on the 
bark of trees, seizing the bark beetles and later laying eggs at the 
openings of their galleries. The larvae invade the galleries and feed 
upon the eggs and larvae of the bark beetles. Felt states that two 
other bark beetles attack the tamarack (160). In this marsh the bark 
beetles have killed a number of trees. In summer the area of dead ones 
may be seen a mile away. 



196 WET FOREST COMMUNITIES 

Farther north the blackburnian warbler nests here. The tree stratum 
of primeval conditions usually included the pine marten (Maries 
americana Tur.). It lives in trees in dark coniferous forests. Merriam 
(142) says that it nests in a hollow tree or log, rarely on the ground. 
It preys upon partridges, rabbits, squirrels, chipmunks, mice, shrews, 
birds' eggs, young birds, and frogs and toads. It disappears when 
civilized man settles the country. The marten's close relative, the fisher 
(Marks pennanti Erx.), is said to be the wildest of all wild animals. It 
is somewhat similar (21, 22, 162) to the marten in habits. 

c) The pine-birch transition girdle (Station 54; Table XL VI). — This 
succeeds the tamaracks and contains a few old trees of this species. The 
pools are all dry in summer, though they may contain water in spring. 
The subterranean stratum has not been investigated. 

The ground stratum includes the frogs of the tamarack formation 
(Hyla pickeringii) . Insects, spiders, centipedes, and snails, which belong 
chiefly to mesophytic forest, are more numerous than in the tamarack 
stage. Nesting of the ruffed grouse likewise indicates that the swamp 
stage is past. The field and shrub strata likewise include more of the 
mesophytic forest animals than the true tamarack stage. 

The tree stratum has not been studied. The trees are white pine, 
yellow birch, and an occasional maple. Felt (137) records no insect 
common to these two trees. There are several common to the white 
pine and tamarack (larch lappet, engraver beetle, etc.). Pines have 
many borers and few leaf-feeders. Each borer usually prefers a certain 
part, as the trunk, limbs, or growing shoots; some, as the white-pine 
weevil (Pissodes strohi Peck) (161), attack young pines. Felt records 
about 25 injurious insects common to birches and maples in general 
and one or two which occur only on yellow birch. The great crested 
flycatcher nests in holes in dead limbs; the wood pewee nests on 
horizontal limbs, and the red-eyed vireo builds a nest in trees from 
5 to 40 ft. from the ground. Dead birches form suitable nesting- 
places for woodpeckers. The Canada porcupine (142) which we have 
noted in the ground stratum is a good climber and feeds largely in 
the trees-, which it often girdles. 

d) The geographic relations of the animals. — Most of the non-aquatic 
animals of the swamps are commonly said to belong to species common 
farther north where conifers dominate. However, our lists and the 
unpublished work of Messrs. Wolcott and Gerhard do not bear out this 
conclusion. Some of the species of these swamps doubtless formerly 
occurred among the hemlocks of Southern Michigan. 



FLOOD-PLAIN FOREST COMMUNITIES 197 

e) Fate of the formation. — ^Most of our tamarack swamps are in the 
regions which are commonly dominated principally by beech and maple. 
In the higher portions of the tamarack swamps are found several species 
characteristic of beech woods and other mesophytic woods. These are 
the wood-frog, the large slug, the snail {Polygyra albolabris) and the 
red-backed salamander (Plethodon cinereus) and the spider {Castianeira 
cingulata). These indicate that beech and maple are to follow. 

4. FLOOD-PLAIN AND RAVINE FOREST COMMUNITIES 

As we have noted on pp. 87-93 ^^^ 108-113, streams often develop 
by head-on erosion into uplands of rock or clay. 

a) Streams developing in rock. — ^In case the upland is of rock, the 
beginning of the stream is a lower place in the slope of the rock through 
which water flows when it is raining. Vegetation is usually absent. If 
there are broken pieces of rock at the sides or in the course of the inter- 
mittent stream, some of the forms mentioned on p. 218 may be present. 
Until it becomes permanent or has cut itself a deep, straight-sided 
channel, it is inhabited by the animals which inhabit the bare rock of 
hills or hillsides. After the stream has cut such a channel, there are 
always small piles of fine soils which support nettles and other mesophytic 
plants similar to those of the old mesophytic flood-plain. Flood-plain 
animals appear early in the development of the stream. 

h) Streams developing in clay. — Along the north shore we have an 
opportunity to study the vegetation of ravines of all ages corresponding 
to the aquatic stages described on pp. 87-93 • The slightly lower places on 
the bluff side in which water runs only when it is raining are usually too 
steep to support plants and animals as regular residents, and have the 
same incidental forms as the steep bluff (p. 210). Later, when the sides 
of the gully become less steep, it is similar to if not identical with the 
second bluff stage (pp. 212-214); later, like the third (p. 215), and still 
later, like the young forest stage. There appears to be little or no 
difference between the bluff and the sides of young ravines. The outer 
ends of ravines as much as a mile and a half long are usually in the shrub 
stage and possess the shrub community. In favored situations the sapling 
forest, apparently identical in its animal associations with that of the bluff 
(p. 215), grows up. Up the stream, well back from the lake, a distance 
of a fourth of a mile, conditions become very different. A very meso- 
phytic forest grows up. In this we have possibly some special features 
under primeval conditions, but in the ravines along the north shore 
where the forest is so much disturbed, ravines do not differ particularly 



198 WET FOREST COMMUNITIES 

from the rest of the forest, but animals of the forest collect in the 
ravines in dry seasons and apparently leave the ravines in the wet 
seasons. 

We have noted that the animal species living at the headwaters of a 
stream may move inland as the headwaters move inland. This is true 
of aquatic species. In the case before us none of the species of the young 
stream are at the headwaters of the older streams because the headwaters 
of the older streams are in the forest of the upland while the young 
streams are in the unforested and exposed bluff of the lake. 

c) Flood-plain communities. — ^In streams not more than a mile long 
we get suggestions of a small flood-plain near the mouth. Here we find 
ragweeds and other pioneer plants with their full quota of animals, such 
as the plant-bug {Lygus pratensis) and other common insects of rank 
pioneer vegetation; willows with their quota of cecropia caterpillars, 
viceroy larvae, willow-beetles, etc., are found here as elsewhere. The 
flood-plains of such small streams are hardly typical because the streams 
are cutting downward so rapidly. They doubtless possess many special 
features of interest which are subjects for detailed and special 
investigation. 

Flood-plain forest is best developed among such streams as the 
DesPlaines River and Hickory Creek. As the stream meanders from 
side to side of its valley, it presents points of deposition and erosion. 
The points of deposition are best for the study of the development of 
flood-plain forest. 

Girdle of bare sand or gravel (Station 66) : On the wet portions of the 
sandy margins one finds the ground beetles (Bembidium) (156), some- 
times toadbugs (p. 180), and more rarely the mole cricket. On the 
higher and drier portions we have taken the Carolina locust {Dissosteira 
Carolina) (40) and the two-lined locust (Melanoplus bivittatus) (40) 
hopping over the ground. 

Girdle of ragweed and helianthus (sub-formation) (Stations 66, 710; 
Table XL VII) : Here (in September) we found several species of spiders, 
the meadow grasshopper, long-legged flies, the leaf-hoppers, and the 
common plant-bug. This girdle is later displaced by willows. 

Willow girdle (sub-formation) (Stations 66, 71a; Table XL VII): 
When herbaceous plants have grown for a few years they become mixed 
with willows which are inhabited by animals common in low forest mar- 
gins. Here (in September) continues the same meadow grasshopper, the 
same plant-bug of the earlier stage. Two different spiders are recorded 
(Pisaurina and Epeira). From willows along other streams we have 



FLOOD-PLAIN FOREST COMMUNITIES 199 

taken the larvae of the viceroy butterfly (163) and the larvae of the 
cecropia moth (Samia cecropia Linn.). Doubtless forest-edge birds 
nest here also. 

The belt which succeeds the willow is commonly found farther from 
the water and has not been so much studied. It is commonly made up 
of larger willows, river maples, young elms, young ashes, and small 
hawthorns. These are usually much tangled with weeds such as nettles, 
and masses of flood trash and vines. General collecting in such a situ- 
ation along Thorn Creek (August) secured for us the large green stink- 
bug {Nezara hilaris), the spiny assassin-bug (Acholla muUispinosa), and 
the broad- winged fulgorid {Ampliscepsa bivittata). On the maples are 
frequently larvae of Symmerista (Fig. 151). On a small hawthorn were 
a number of larvae of the handmaid moth (Datana). At this stage the 
trees and shrubs become the nesting-places of the yellow warbler and 
American goldfinch, which are probably our most characteristic early 
flood-plain birds. 

In the wet ground of the flood-plain, especially in any small depres- 
sions made by overflows, the crayfish (Cambarus diogenes) is the charac- 
teristic resident. Under driftwood and on the plants of the water 
margin is the slug (Agriolimax campestris), and often also the snails 
(Succinea retusa and avara). 

Such situations are also the chief haunts of the beaver, which cuts 
away the saplings to make its dams. The otter {Lutra canadensis) is 
particularly fond of stream margins. It feeds upon crayfishes, fishes, 
frogs, etc. It has particular powers of traveling long distances and a 
curious habit of sliding down mudbanks and snowbanks for sport (142). 
In winter it progresses on ice by repeatedly running a distance and then 
sliding as far as the momentum will carry the body. The nest is nearly 
always in the stream bank, with the entrance below water. The skunk, 
the mink, and the raccoon are also fond of the stream-margin thicket, the 
latter picking up fish or crayfish if they can be had at night. This animal 
is said to wet its food before devouring it; hence the "wachbar" of the 
Germans. The skunk likewise devours almost anything that is to be 
had at the water's edge. 

d) Flood-plain forest association (Station 68; Table XL VIII). — As 
times passes the river cuts lower, the forest develops, and we have 
a dense forest of elm, hawthorn, ash, and basswood, with sometimes 
walnut and butternut, these being partially displaced on the higher 
ground by the oaks. This we may regard as the typical flood-plain 
forest. 



200 



WET FOREST COMMUNITIES 



Subterranean-ground stratum: The nymphs of the seventeen-year 
cicada and the two-year cicada together with earthworms are always 
numerous. The latter comes out on the ground under a log and ascends 
under the bark of dead trees during wet weather. 

On the ground one finds slugs {Agriolimax campestris) . Under 
leaves, logs, and bark are snails (Circinaria concava, Polygyra profunda, 




Representatives of the Flood-Plain Forest Animal Communities 

Fig. 151. — A caterpillar (Symmerista albifrons) on the leaf of the soft maple; 
natural size. 

Fig. 152. — The common land sowbug {Porcellio rathkei); twice natural size. 
Fig. 153. — The scorpion fly (i'a«or/»o t)ewo5fl) ; much enlarged. 
Fig. 154. — A sphinx caterpillar from Virginia creeper; natural size. 
Fig. 155. — The unicorn larva from dogwood; enlarged. 



Pyramidula alternata, and Polygyra clausa, and rarely thyroides). Land 
sowbugs are common (Fig. 152). Of the centipedes we note the long 
ground form (Geophilus sp.) and sometimes the large millipede (Spiro- 



FLOOD-PLAIN FOREST COMMUNITIES 



20I 



bolus marginatus). The white-footed wood-mouse {Peromyscus leucopus 
noveboracensis Fisch.) nests usually under a stump or a log though some- 
times slightly under ground or in hollow trees (21). The short- tailed 
shrew {Blarina brevicauda Say) and the common shrew {Sorex personatus 
St. Hil.) are common residents. 

In the earlier days (22) the ground stratum was occupied by the 
larger mammals. The black bear doubtless found the delicate herbace- 
ous plants desirable at certain times of the year. The Virginia deer 
occurred here commonly, and the bison and elk invaded the flood-plain 
forest in going to the rivers to drink. The timber wolf and the common 
fox, both of which formerly frequented 
all parts of Illinois, were no doubt also 
to be found. 

Under fallen logs we find all the 
animals that are found on the forest 
floor, and some others also. When a 
tree first falls to the ground, if it be 
still solid or living, the animals which 
attack it are the same as those which 
attack it when it is standing. If the 
tree be an oak or a basswood, one of 
the first of these is the weevil {Eupsalis 
minuta) (Fig. 156) (155), which bur- 
rows into the wood. Later the larvae 
of some of the long-homed beetles are 
found working under or in the inner 

layers of the bark. These are followed by the Tenebrionidae and the 
Buprestidae larvae, or flat-headed borers (137). All these tend to let 
the water between the trunk and bark, which meanwhile has been 
loosening with every rain, then drying, freezing, and thawing, until it 
soon becomes quite loose. The space between bark and log is loosely 
filled with the castings of the many animals that have worked over the 
outer wood and bark, and with wood and bark that have decayed with- 
out the aid of these animals. At such a time the space between bark 
and log becomes the abode of the flattened larvae of Pyrochroidae, 
centipedes, slugs, ground beetles, and nearly all of the small animals 
mentioned as belonging to the ground stratum proper. Fallen logs are 
also the nesting-places of the weasel {Mustela noveboracensis) (142, 143), 

In the autumn we find many hibernating animals under the leaves of 
the floor of the flood-plain forest. Here we have found water-striders, 




Fig. 156. — ^An oak borer (Eupsalis 
minuta Drury): a, larva; 6, pupa; 
c, adult female; d, head of adult 
male; details of parts are indicated 
(after Riley). 



202 WET FOREST COMMUNITIES 

the cutworms from the field stratum, the stinkbugs and leaf-bugs from 
the river margin, and large white-faced hornets (Vespa mactdata). 

Field stratum: In early summer the forms of the field stratum are 
most in evidence. There are scorpion-flies (Fig. 153, p. 200), the males of 
which have curious clasping organs at the posterior end of the abdomen. 
Bittacus, the long-legged insect, closely related to the former, flies about 
among the nettles; it has the curious habit of seizing flies with its hinder- 
most pair of legs and holding them while they are being devoured. In 
their breeding both of these insects belong to the ground stratum. 

The harvestmen, or daddy-longlegs, are always in evidence, crawl- 
ing over the nettles {Liobunum dorsatum and ventricosum being most 
common). Several spiders {Leucauge hortorum and Theridium frondeum) 
occur. Numerous bugs including Reduviolus annulatus, syrphus flies 
{Syrphus americanus), and aphids, with the various enemies which occur 
with them, are common here. After rains we find many animals of the 
ground stratum on the nettles and the trunks of trees. We have noted 
the slugs {Agriolimax campestris) and the snails {Polygyra profunda and 
thyroides) here. 

Shrub stratum: The shrub stratum is well developed. The dogwood 
is one of the characteristic shrubs, and in early summer its leaves usually 
are covered with small bunches of foam which upon inspection are found 
to contain a small insect, the spittle insect {Aphrophora). The unicorn 
larva (Fig. 155) (163) feeds on the leaves of the dogwood, and the sphinx 
larva on the Virginia creeper (Fig. 154a). 

Tree stratum: The tree stratum has not been especially studied. 
The trees above the level of the shrub stratum are inhabited by many 
borers, lepidopterous larvae feeding on the leaves, and many birds nesting 
in the branches. The raccoon is especially fond of nesting high in hollow 
trees of the flood-plain forest. The opossum, which was never abundant 
near Chicago, found a suitable place in the trees of the flood-plain with 
its wild grapes and tender herbs. Under natural conditions this is one 
of the chief haunts of the gray squirrel, now familiar in our parks (21). 
For birds frequenting the flood-plain, see Baker (100, pp. 476-78). 

The most striking peculiarity of the flood-plain forest is its frequent 
inundation. In the spring of 1908 we found the flood-plain of the north 
branch of the Chicago River inundated at a time when the nettles were 
but a few inches high. On the small nettles we found the common small 
slug {Agriolimax campestris) and the snails {Succinea avara and retusa) in 
great abundance. Caught in a comer behind a tree in some driftwood 
we found a carpenter ant (Camponotus), some flood-plain cutworms, 



FLOOD-PLAIN FOREST COMMUNITIES 203 

crane-fly larvae, and ground beetles. These had been swept into this 
position by the current. Wood (21) says that the white-footed mice 
and shrews climb the trees when the stream is in flood. As the number 
of animals does not seem to be decreased after floods, the animals of the 
lower strata of the flood-plain forest must be able to withstand sub- 
mergence for days at a time. The fact that these floods come in spring 
and winter when the animals are inactive doubtless assists in preserving 
them because of the low ebb of their metabolic processes. 

e) Succession in the flood-plain forest. — As the stream works over its 
flood-plain, it is constantly destroying the forest at some points and 
depositing new materials upon which a new series develops at other 
points. The depositing sides of the curves present the early forest 
stages. Back of these and higher above the stream are the older stages. 
Thus the horizontal series which we see when we pass from a depositing 
bank across the various terraces is a duplication of the vertical series at 
the oldest point or on the highest terrace. 

The higher and drier parts of the plain left by the lowering of the river 
bed, and much of the flood-plain proper, are often well drained, rarely 
flooded, and when thus drained pass rapidly into the oak-hickory type. 
At such a stage the oak-hickory animal association is present and the 
characteristic flood-plain animals have disappeared. 

/) Comparison with other moist forests. — ^There are a few species 
common to the marsh and flood-plain forests. This is true of several 
mammals and insects. One of the most characteristic of the insects is 
the scorpion-fly. Many of the others belong particularly to the trees 
common to the two, such as the ash, elm, basswood, etc. 



204 



WET FOREST COMMUNITIES 
TABLE XLIII 



Animals from the Open Pre-Tamarack Bog Dominated by Bulrushes, 

Sedges, and Similar Plants 
Animals recorded from Tamarack Swamps; M from the swamp at Mineral 
Springs, Ind. (Station 54), and P from that near Pistakee Lake, 111. (Station 54a). 
Numbers refer to month in which the specimens were taken, f indicates that the 
species has been taken from low prairie; * that it has been taken from high. 



Common Name 


Scientific Name 


Habitat 


Marsh and 
Month 


Midge larva 


Chironomus sp 


Pitcher-plant 


M5 


Mosquito larva 

Caterpillar 


Wyeomyia smithii Ccj 


" 


M 5 


Noctuinae larva 


(( 


M 5 


Ground beetle (dead) 


Amara polita Lee 


« 


Ms 


*Orb-weaving spider 








(dead) 


Epeira foliala Koch 


u 


M5 


* Jumping spider 








(dead) 


Phidippus podagrosus Htz 


u 


Ms 


Snout-beetle (dead) . . 


Listronotus callosus Lee 


u 


M s 


Ant (dead) 


Dolichoderus mariae Forel 


a 


Ms 


Water-beetle 


Helophorus lineatus Say 


Pool 


P 8 


Flat snail 


Planorbis parvus Say 


u 


P 8 


Crayfish 


Cambariis diogenes Gir 


u 


Ms 


Entomostraca 




u 




Snail 


Succinea retusa Lea 


« 


M 5 


Snail 


Circinaria concava Say 


u 


Ms 


tSpider {Pisauridae) . 
Running spider 


Pisaurina undata Htz 


Surface ground 

« 


M 5 


Pirata montana Em 


Ms 


fMarsh rattlesnake . . 


Sistrurns catenatus Raf 


a 


Ms 


Ground beetle 


Platynus picipennis Kirby 


u 


M 5 


Harvestman 


Liobiinum grande Say 


Vegetation 

u 


M s 


*Orb-weaving spider. . 


Epeira prompta Htz 


Ms 


t*Orb-weaving spider. 
JGarden spider 


Pleclana stellaia Htz 


u 


M s 


Argiope trifasciata For 


a 


P 8 


fDictynid 

*Crab spider 


Dictyna sublata Htz 


. u 




Runcinia aleatoria Htz 


« 


P 8 


tCrab spider 

Jumping spider 


Tibellus duUoni Htz 


u 


P 8 


Dendryphantes octamis Htz 


a 


P 8 


Jumping spider 

t Orb- weaving spider . 


Thiodina puerpera Htz 




Ms 


Eugnatha straminea Em 


u 


Ms 


Meadow grasshopper . 


Orchelimum glaberrimum Burm . . 


u 


P 8 


Hoosier locust 


Paroxya hoosieri Bl 


u 


P 8 


t*Grasshopper {Acri- 








didae) 


Stenobothrus curtipennis Harr 

Pelogonus americanus Uhl 

Lepyronia quadrangularis Say . . . 


a 


P 8 


fToad-bug 


u 


Ms 


Bug (Cercopidae) 


u 


P 8 


Bug (fulgorid) 


Pentagramma vittatifrons Uhler . . 


« 


P 8 


Braconid 




a 


P 8 


Ant 


Formica fusca Lin 


P 8 


Fly {Sciomyzidae) . . . . 
Snout-beetle 


Sepedon pusillus Loew 


a 


Ms 
Ms 


Baris confinis Lee 


a 


Snout-beetle 


Brachybamus elecius Germ 


u 


Ms 


*Lampyrid beetle .... 
Snout-beetle 


Telephorus lineola Fab 


u 


Ms 
Ms 


Listronotus inaeqtialipennis Boh . 


u 



WET FOREST ANIMALS 



205 



TABLE XLIV 
Animals Recorded from Margin of Tamarack Forest — Forest Edge 
Abbreviations as in Table XLIII 



Common Name 



Scientific Name 



Habitat 


Locality 
and Month 


Ground 


P 9 


u 


Ms 


u 


Ms 


u 


Ms 


a 


Ms 


ti 


Ms 


a 


Ms 


u 


Ms 


u 


Ms 


u 


Ms 


Shrubs 


M s 


« 


Mq PS 


u 


P 8 


u 


P 8 


« 


P 8 


a 


Ms 


u 


M9 


u 


Ms 


Young tamarack 


M9 


u 


M9 


u 


M9 


u 


M 9 


u 


P 8 


a 


P 8 


u 


Ms 


u 


P 8 


u 


P 8 


u 


P 8 


u 


P 8 


a 


Ms 


a 


Ms 



Spider 

Snail 

Slug.... 

Camel cricket 

Millipede 

Firefly larva 

Tortoise beetle .... 

Ground beetle 

Tree-frog 

Crab spider 

Stinkbug 

Jumping spider .... 
Orb-weaving spider. 
Orb-weaving spider. 

Katydid 

Ant 

Pickering's frog . . . 

Beetle 

Earwig 

Brindled locust .... 
Orb- weaving spider. 
Jumping spider .... 

Sawfly larva 

Caterpillar 

Fly 

Spider 

Long-bodied spider. 

Harvestman 

Jumping spider .... 

Red mite 

Ground beetle 



Argiope trifasciata For 

Vitrea indentata Say 

Agriolimax campestris Binn. . . . 

Ceuihophilus sp 

Polydesmus sp 

Lampyridae sp 

Coptocycla bicolor Fab 

Pterostichus lucublandus Say . . . 

Hyla versicolor Lee 

Philodromtis ornatus Bks 

Euschislus tristigmus Say 

Dendryphantes milUaris Htz. . . . 

Epeira trifoliutn Htz 

Epeira trivittata Key 

Amblycorypha sp 

Formica fusca Linn 

Hyla pickeringii Hoi 

Languria gracilis Newm 

Apterygida aculeata Scud 

Melanoplus puncttilatns Scud. . . 

Epeira gigas Lea 

Dendryphantes tniliiaris Htz. . . . 

Nematinae 

Geometridae 

Mesogramma marginata Say . . . 
Chiracanthium inclusa Htz . . . . 

Tetragnatha grallator Htz 

Liohunum dorsatum Say 

Dendryphantes octavus Htz 

Trotnbidium sericeum Say 

Platynus decens Say 



2o6 



WET FOREST COMMUNITIES 



TABLE XLV 

Tamarack Forest 

For meaning of abbreviations see Table XLIII 



Common Name 



Scientific Name 



Habitat 



Locality 
and Month 



Mosquito 

Amphipod 

Sowbug 

Copepod 

Copepod 

Copepod 

Copepod 

Spider (lycosid). 

Spider 

Millipede 



Culex canadensis Theob 

Eucrangonyx gracilis Sm 

Asellus communis Say 

Canlhocamptus northumbricus Br 
Cyclops viridis americanus Mar . . 

Cyclops serrulatus Fisch 

Cyclops albidus Jurine 

Pirata piralica CI 

M angora maculata Key 

Scytonoius gramilatus Say 



Millipede. 



Polydesmus sp . 



Snail 

Slug 

Snail 

Crane-fly larva . . 
Ground beetle . . . 
Swamp tree-frog. 

Wood-frog 

Snail 



Ground beetle . 
Ground beetle . 



Zonitoides arboreus Say 

Philomyctis carolinensis Bosc. 

Circinaria concava Say 

Tipulidae 

Plerostichus coracinus Newm . 

Chorophilus nigritus Lee 

Rana sylvatica Lee 

Polygyra muUilineata var. 

algonquinensis Nason . . . . , 
Plerostichus adoxus Say 



Engraver beetle 

Engraver destroyer 

(larva) 

Borer (larva) 

Spider 

Spider 

Spider 

Leaf -hopper 

Leaf-bug 

Tree-hopper 

Caterpillar 

Beetle (Melandryidae) 

Tortoise beetle 

Jumping spider 

Orb-weaving spider. . . 
Orb-weaving spider. . . 

Long spider 

Jumping spider 

Jumping spider 

Dietynid spider 

Leaf -hopper 

Bug 

Leaf-bug 

Leaf -hopper 

Spider 



Plerostichus pennsylvanictis Lee 

Polygraphus rufipennis Kirby . . 

Thanasimus dubius Fab 

Cerambycidae 

Epeira ocellata CI 

Habroceslum pulex Htz 

Theridium frondeum Htz 

Gypona striata Burm 

Poecilocapsus lineatus Fab. ?. . . 
Ceresa borealis Fair 



Synchroa punctata Newm 

Coptocycla clavata Fabr 

Zygoballus bettini Peek 

Epeira gigas Lea 

Epeira foliata Koch 

Tetragnatha grallator Htz 

Dendryphantes octavus Htz. . . . 
Dendryphanles mililaris Htz . . 

Dictyna foliacea Htz 

Cicadula variata Fall 

Scaphoideus immistus Say .... 

Lygus plagiatus Uhler 

Gypona octolineata Say 

Pisaurina undata Htz 



Pools 



Sphagnum 

u 

Under log and 

bark 
Under log and 

bark 
Under log 



Under log 



Ground under 

bark 
Ground under 

bark 
Ground under 

bark 
Early decay 



Decaying wood 

« 

Under loose bark 
Herbs 



Undergrowth 



M 5 P8 
M 59 
M 5 9 
M 69 

M9 

M9 

M 9 

M9 

M9 

M9 

M9 

Mqs 
M9 

M9S 

M9 
.M9 

M9 

M 59 
P 8 

Ms 

M9 

M 59 

M 59 
M59P8 
P 8 
P 
P 
P 
P 
P 
P 

P 8 
P 8 
M9 
M59 
M9 
M9 
M5 
Ms 
Ms 
M9 
M9 



WEI' FOREST ANIMALS 
TABLE XLV— Continued 



207 



Common Name 


Scientific Name 


Habitat 


Locality 
and Month 


Beetle (Dertnestidae) . . 


Cryptorhopalum haemorrhoidale 
Lee. 


Undergrowth 

u 
a 
a 
u 
u 
a 

Low shrubs 

u 

Shrubs 


M9 


Beetle (Scarabaeidae) 

Lady-beetle 

Beetle (Dascyllidae) . . 
Beetle (Dascyllidae) . . 
Beetle (Melandryidae) 

Pummice-fly 

Ant 


Chalepus nervosa Panz 


M 5 


Psyllobora 20-maculata Say 

Cyphon variabilis Thunb 

Cyphon padi Linn 


Ms 
Ms 
Ms 


Allopoda lutea Hald 


Ms 


Drosophila amoena Loew 

Formica fusca Linn 


Ms 
Ms 


Dictynid spider 

Spider 


Dictyna sublata Htz 


Ms 


Hypselistes florens Cam 


Ms 







TABLE XLVI 

Animals of the Birch-Maple Belt, Which Succeeds the Tamarack at 
Mineral Springs 

(Station 54) ' 



Common Name 


Scientific Name 


HabiUt 


Month 


Red mite 


Trombidiutn sericeum Say 

Polygyra albolabris Say 

Pterostichus adoxus Say 

Phloeotrya quadrimaculata Say. . . 
Listotrophus cingulatus Grav .... 

Castianeira cingulata Koch 

Xiphydria tnaculata Say 

Rana sylvatica Lee 


Ground 

u 
a 
u 
u 
« 
« 
u 
« 

Herbs 


s 


Snail 




Ground beetle 

Melandr3nd beetle . . . 

Rove beetle 

Clubionid spider 

Horntail 


S 
S 
S 
5 
5 

s 


Salamander 


Plethodon cinereus Gr 


s 


Salamander 


Plethodon glutinosus Gr 

Agelena naevia Wal 


s 







Tree-frog . . . 


Hyla pickeringii Hoi 


" ! 


Spider 


Phidippus audax Htz 


Shrubs 

u 
u 
u 
« 

u 

u 


s 


Spider 


Dendryphantes militaris Htz .... 

Misumessus oblongus Keys 

Cyphon padi Linn 


s 


Spider 


s 


Beetle 


s 


Beetle 


Photinus corruscus Linn 

Camponotus herctdeanus ligniper- 

dus var. noveboracensis Fitch. . 
Calligrapha multipunclata var. 

bigsbyana Kirby 


s 


Ant 




Leaf -beetle 


9 




Q 









208 



WET FOREST COMMUNITIES 



TABLE XLVII 

Animals Occurring in the Ragweed and Willow Thicket Stages of Flood- 
Plain Forest Development 
(Stations 66, 67, 71a) 
Ragweed Stage 



Common Name 


Scientific Name 


Habitat Month 


Snail 


Succinea avara Say 


'.'.'.'...'. 8- 

8- 

8- 




Snail 


Succinea retusa Lea 




Meadow grasshopper. 
Tarnished plant-bug. . 
Spider 


Xiphidium brevipenne Scud 

Lygus pratensis Linn 


-9 


Argiope tr if as data For 


-0 


Long-bodied spider. . . 
Meadow grasshopper. 


Tetragnalha laboriosa Htz 

Orchelimutn glaberrimum Burm . . 


-9 
-9 


Thicket Stage 


Snail 


The Succineas above continue 
Succinea ovalis Say 


Plants 
WiUow 

u 

Grape 

Weeds and willow 

Haw 

Willow 

Willow '. 

u 
u 
a 




Katydid 


Amblycorypha oblongifolia DeG. . 
Pelidnota punctata Lin 




Grape scarabaeid .... 

Fulgorid bug 

Cercopid bug 

Assassin-bug 

Stinkbug 




Amphiscepa bivittata Say 

Lepyronia quadrangularis Say . . . 

Acholla multispinosa DeG 

Nezara hilaris Say 




Spider 


Pisaurina undata Htz 




Spider 


Epeira gigas Lea 




Bythoscopid bug 

Sawfly larva 

Leaf-beetle 


Idiocerus snowi G. and B 

Cimbex americana Lea 




Crepidodera helexinus Lin 









TABLE XLVIII 

Animals Usually Common on Herbaceous Vegetation (Chiefly Nettles) of 
THE Riverside Flood-Plain Forest (Oak-Elm Stage) in June and July 
Those starred occur in the corresponding stages of marsh forests. 



Common Name 


Scientific Name 


*Dictynid spider 


Dictyna foliacea Htz. 


*Spider 


Theridium frondeum Htz. 


Spider {Epeiridae) 


Leucauge hortorum Htz. 


*Harvestman 


Liobunum dorsatum Say 


*Harvestman 


Liobunum ventricosum Wood 


False crane-fly 


Bittacus strigosus Hag. 


*Scorpion-fly 


Panorpa venosa Westw. 


♦Snail 


Polygyra thyroides Say (moist days) 


Lampyrid beetle 


Podabrus rugulosus Lee. 


Long-horned beetle 


Strangalia acuminata Oliv. 


Click-beetle 


Limonius interstitialis Melsh. 


Scarabaeid beetle 


Chalepus scapularis Oliv. 


Snout-beetle 


Rhinoncus pyrrhopus Lee. 


Damsel-bug 


Reduviolus annulatus Reut. 


Capsid bug 


Plagiognathus fuscosus Prov, 


Fly {Psilidae) 


Loxocera pectoralis Loew. 







CHAPTER XII 
ANIMAL COMMUNITIES OF DRY AND MESOPHYTIC FORESTS 

I. Introduction 

The forest communities discussed in the preceding chapters are those 
displacing aquatic communities. In a climate suitable for forests, trees 
spring up on high, well-drained surface materials of all kinds. Forest 
appears on rock, sand, clay, etc., first as shrubs or scattered trees, later 
as dense mesophytic forest. In the region about Chicago we have forest 
in all stages of development and on several kinds of material. 

The bluffs of the lake and artificial exposures of clay along the drain- 
age canal and the till uplands afford examples of development peculiar 
to this type of soil. The few outcrops of Niagara limestone and the 
quarries and rock dumps present scattered data on the history of forests 
on rock. The extensive sand areas afford examples of all stages of 
development peculiar to sand. From all these situations, we find 
forests leading toward some type related to climate, either the typical 
forest of the forest climate, or the forest of the savanna climate. 

II. FoEEST Communities on Clay 
(Fig. 157) (55) 

The chief areas of more or less active erosion are along the west side 
of the lake, from Waukegan to Winnetka, and on the east side of the 
lake from South Haven to Benton Harbor. The old bluffs of the Tolles- 
ton and Calumet stages as represented north of Waukegan and at 
various other points offer valuable areas for comparison. There are 
also similar bluffs along many of our streams, some of those in Michigan 
being very old. 

When the ice sheet receded entirely and left the outline of Lake 
Michigan much as it is now, doubtless the shore presented a more or less 
rounded profile. However, since that time waves have gradually 
changed the shore profile. By washing away the clay at the base of 
such a shore, a bluff has been developed (62). 

I, STEEP BLUFF ASSOCIATION 

(Station 56; Table XLIX) 
a) Ground stratum (55) (Fig. 157). — -In spring, when the frost goes out 
of the ground, leaving the clay somewhat loosened, the ground-water 

209 



2IO 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



level is high, and gravitation overcomes the viscosity of the clay, and 
great masses, whose consistency is that of thick mud, slump down in the 
form of landslides. This process naturally decreases the angle of slope at 
the points where the slumping takes place. Slumping does not occur 
equally everywhere and the bank becomes very irregular. Under such 
conditions the only animals present are the Collembola. In summer the 
steep bank dries. No animals are present as actual residents. The 
bank serves only as a casual alighting-place for tiger-beetles, butterflies, 
bees, flies, and other insects. Few or no plants are present. 




157 



Fig. 157. — Upper figure is a 
diagram showing Lake Michigan 
bluff as seen from the zenith. 
U, level surface of upland; BL, 
bluff; SB, sandy beach; M, 
water of Lake Michigan; /, 
piers; toward the left is north; 
sand has lodged on the north side 
of the piers. AB and CD indi- 
cate positions of cross-sections 
below. Middle figure is a cross- 
section AB. Slumping bluff 
stage. The adults of Cicindela 
limbalis are distributed from A 
to B; the larvae, sparingly, from 
E to F. Other letters as in the 
upper figure. Lower figture is a 
cross-section CD; stage of some 
bluff stability and bare clay 
exf>osure. Adults of limbalis 
between C and D; larvae plenti- 
ful between G and H. Other 
letters as above. Reprinted 
from the Journal of Morphology. 



Unless something interferes with the action of the waves the same 
series of events just described continues from year to year. If for some 
reason the action of the waves is checked, the associated processes will 
be checked also. At various points along the shore piers have been built 
out into the water at right angles to the shore for a distance of a hundred 
meters or more (Fig. 157). The currents in the lake are southerly in 
direction along the west shore. Whenever water in motion, laden 
with material picked up by its action against the bluff, strikes one of 
these piers, its velocity is decreased and a part of the material is dropped 



ON CLAY 



211 



on the north side of the jetty. Materials thus deposited gradually 
pile up to such an extent as to protect the base of the cliff from 
wave-action. Thus the effect of the slumping of the springtime 
((vhich tends to reduce the angle of slope) is not fully removed from 
year to year. 

d a 



Wg^- 




£ 




Hi 4^ 


^ ^ 


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.« ^SkJ^SL^j^ .A. 


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■-■.' ■ '■■■fr. 


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1-iG. 158. — The bluff habitats near Glencoc, 111., showing several stages in the 
development of the forest on the bluff. The area to the right of a line between a and b 
is stable enough to support some sweet clover. Here the tiger-beetle larvae, spider, 
etc., are most abundant. The area between lines joining a and b and a and c is in the 
early shrub stage. To the left of ac the shrubs are denser and larger, and some trees 
are present. Reprinted from the Journal of Morphology. 



2. SWEET-CLOVER ASSOCIATION 

(Fig. 158) (55) 
Under the condition described above, the water of rainfall, as well 
as the slumping, reduces the angle of slope, and the bluff becomes more 
and more stable. Some of the clods of turf from the top of the bank 
stop half way down the slope. The bluff begins to support a few xero- 
phytic plants, such as the sweet clover, asters, etc. 



212 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



^' \A/>V/ 





161 




162 163 

Life History of the Clay-Bank Tiger Beetle 
(Reprinted from the Journal of Morphology) 

Fig. 159. — From left to right — the ventral, side, and dorsal view of the oviposi- 
tor of the bln£E tiger-beetle (Cicindela limbdis) with segments numbered; 3 times 
natural size. 

Fig. 160. — ^The egg of the same in the hole in the ground made by the ovi- 
positor; i^ times natural size. 

Fig. 161. — ^The egg; 3? times natural size. 

Fig. 162.— The larva, side view; h, hooks; 3 times natural size. 

Fig. i63.^The anterior half of the larva: an, antennae; mp, maxillary palp; 
m, mandible; 0, ocelli; 3 times natural size. 

Fig. 164. — ^The pupa; 3 times natural size. 




Fig. 16.1;. — ^The burrow of C. limbalis, pupal cell; i natural size. 



ON CLAY 



213 



a) Subterranean-ground stratum. — Perhaps the most characteristic 
animal of the steep bluflf is the bluff tiger-beetle (55, 151) {Cicindela 
purpurea limhalis) (Figs. 159-67). In the open places of this stage, the 
larvae, which live in curved cylindrical burrows (Figs. 165, 166), are 
common. 

The female beetle is provided with an ovipositor (Fig, 159) adapted 
to making small holes in the clay in which eggs are laid (Figs. 160, 161). 




Clay-Bank Inhabitants 
Fig. 166. — View of larval burrow of the tiger-beetle; natural size. 
Fig. 167. — The adult tiger-beetle {Cicindela limhalis); about twice natural size. 
Fig. 168. — The clay-bank spider {Pardosa lapidicina) . 
Fig. 169. — A snail of the shrub stage (Po^ygyra wow(7Jo«) ; enlarged. 
Fig. 170. — Th&sn&W {Poly gyrathyroides); enlarged. 



The larva (Figs. 162, 163) on hatching from the egg digs a burrow in the 
position of the ovipositor hole. The eggs, which are laid in June, hatch 
in two weeks and the larvae live in the spot where the eggs were laid 
for one year, and transform into pupae (Fig. 164) in the ground in an 
especially prepared cavity (Fig. 165). The adult, which is a reddish- 



214 DRY AND MESOPHYTIC FOREST COMMUNITIES 

green form (Fig. 167), appears in the autumn and lives over winter in 
the ground (151). 

The tiger-beetle larvae are found on the bare spots and sometimes 
among the sweet clover (eggs are laid before the clover is full grown). 
They feed on any animals that crawl over the clay within reach — any 
that we mentioned may fall victims. 

As physiographic processes go on, we find that more animals make 
their appearance, bristle-tails creep out of the cracks in early spring, and 
occasional slugs and geophilids are found hiding under clods. A large 
black spider {Pardosa lapidicina) (138) (Fig. 168) and many smaller 
species are present also. More rarely one of the land snails {Pyramidula) 
is present at this time of year, crawling about under the dead vegetation. 
The mud-dauber wasp {Pelopoeus cementarius) secures its mud (40) 
and the Carolina locust {Dissosteira Carolina) probably breeds here. 

b) Field stratum. — Under such conditions, as summer advances the 
sweet clover grows up, and as soon as it is of considerable size it is 
attacked by aphids, which form the basis for a small consocies of inter- 
dependent animals. Many coccinelids come to feed on aphids, and 
parts of adult coccinelids have been found in the burrows of the tiger- 
beetle larvae. The golden-eyed lacewing (Chrysopa oculata) deposits 
stalked (p. 291) eggs on the plant; soon its larvae — the aphis-lions — 
are devouring aphids, as do also the larvae of syrphus flies (164). 

Crab-spiders {Runicina aleatorifi, Misumena vatia) (138) lie in wait 
in the clover flowers and thus capture the nectar- and pollen-seeking 
flies, such as Eristalis tenax (Fig. 271, p. 270) and Syrphus ribesii Lin. 
(165). The common plant-bug {Adelphocoris rapidus) (Fig. 262, p. 266) 
is especially abundant in autumn. The honey-bee {Apis mellifera) and 
a bumblebee {Bombus americanorum) come in numbers for nectar and 
pollen. Grasshoppers, such as Scudderia, Melanoplus femur-rubrum, 
etc., are common, and when young may fall prey to spiders such as orb- 
weavers (Epeira trivittata). Parasitic hymenoptera (Pimpla conquisitor 
Say) are also common. 

3. SHRUBS ASSOCIATION (a FOREST MARGIN SUB-FORMATION ) 

A little humus accumulates locally through the decay of sweet 
clover. The roots of plants in the soil and the undecayed trunks of 
the sweet clover hold this and the mineral soil in place against the 
action of the rain as it falls on the slope. Conditions become ripe 
for the germination of the seeds of other plants and for the breeding 
of other animals. Shrubs, such as the willow and shad-bush, appear 



ON CLAY 215 

as scattered individuals here and there, and bring with them new 
conditions and animal forms. 

a) The subterranean-ground stratum. — In addition to Pyramidula 
mentioned above, other snails appear, especially in the more moist spots 
on the bank. These are Zonitoides, Polygyra monodon (Fig. 169), 
and P. thyr aides (Fig. 170). Centipedes (Geophilus) and millipedes 
(Polydesmidae) become more numerous, while the spiders {Pardosa 
lapidicina) (Fig. 168), the tiger-beetle larvae, and other soil-inhabiting 
forms decrease. 

b) Field stratum. — ^The field stratum of the shrub stage does not 
differ strikingly from the preceding, as it consists mainly of plants of 
the earlier stage scattered among the shrubs. 

c) Shrub stratum. — Here we have the characteristic inhabitants of 
shrubs. On the young aspens and willow are the larvae of the viceroy 
butterfly (163). The common gall on the willow is the pine-cone gall, 
caused by Cecidomyiidae (137). Beneath the leaves of the cone we have 
found long slender eggs of some orthopterous insect (probably Xiphidium 
ensiferum) (40, p. 428). We have no record of the nests of birds, but 
many of the forest margin birds nest here (see pp. 274-75 and Table 
LXIV, p. 277). 

4. YOUNG FOREST STAGE 

(Fig. 171) 

Shrubs and seedlings of trees become more and more numerous. 
The sweet clover and most of the animals associated with it disappear. 
Young trees, such as oak, hickory, hop, hornbeam, etc., grow and usually 
give rise to a sapling forest. 

a) Subterranean-ground stratum. — This stratum has all the characters 
of the more dense and mesophytic forest ground stratum and largely be- 
cause of the springy character of the bluff which supplies much moisture. 
The woodchuck {Marmota monax) (142) sometimes digs in these banks. 
In the open places in which small areas of soil are covered with only a 
few leaves we find the larvae of the green forest tiger-beetle (Cicindela 
sexguttata) (55, 151) which lays eggs in shaded places (Figs. 172, 173). 
Under the leaves the snails, which were recorded in the younger stages, 
and sowbugs are present. We find snails and slugs (Polygyra profunda 
[Fig. 220, p. 237] and albolabris [Fig. 240, p. 243], Philomycus caro- 
linensis [Fig. 231, p. 241]), which are commonly abundant in dense 
woods. The Myriopoda are also more numerous and belong to different 
species. Fontaria corrugate (Fig. 218, p. 237), which has the margins 



2l6 



DRY AND MESOPHYTIC FOREST COMMUNITIES 




The Bluff Forest 

Fig. 171. — ^An open place in the oak and hickory forest of a Tennessee mountain- 
side, a typical green tiger-beetle {Cicindela sexguttata) habitat. The individuals were 
seen copulating on the log in the foreground. The general aspect is very similar to 
that of the bluff forest. (Reprinted from the Journal of Morpltology.) 





72 173 

Fig. 172. — ^The black dots represent the distribution of the larvae of C. sexguttata 

from eggs laid in a cage. The larvae are in the exact position in which eggs are laid. 

The stippled area is in shadow in the middle of the day. 
Fig. 173. — Diagram of a burrow of Cichtdela sexguttata. 



ON ROCK 



217 



of the segments striped with yellow, is one of the most characteristic 
of moist^woods,'\vhile others (Geophilus rubens and Lysiopetalum lac- 
tarium) are not uncommon. Ground beetles (Calathus gregarim Say) 
and bugs (Reduviolus subcoleoptratus) occur. In logs of fallen basswood 
we found the larvae of Tenehrionidae and Cerambycidae and of horntails, 
the burrowing hymenoptera, and the Mycetophilidae larvae (Sciara) 
(Fig. 174) (165). 

c) Field stratum and shrub stratum. — The field stratum has been but 
little studied. We have taken a few Scudderia nymphs, some spiders, 
and bugs, but no adequate study has been carried on. 

d) Tree stratum. — ^This has likewise been but little studied, but in 
these young forests, while the ground stratum is like that in the older 
forest, the tree stratum is poorly de- 
veloped because the trees are short 
saplings. As time goes on, however, 
the forest becomes more dense. Such 
a forest may be seen on the bluff at 
Lake Bluff, 111. 




5. OTHER BARE CLAY FORESTS 

Other bare clay young forests may 
be seen along the dumps of the drainage 
and Chicago-Michigan canals at Summit. 
Here we find practically the same stages 
as at Glencoe on the lake bluff. There 
are the steep clay bluffs with no perma- 
nent residents, the semi-stable bluffs, or 
weed-occupied areas. These are like the 
semi-stable bluffs at Glencoe but the tiger-beetle is another species and 
selects more nearly level places; otherwise it is very similar in habits. 

The shrub stage occurs but is without the snails, since the ground- 
water level is lower and the moisture in the soil of the lake bluff is wanting 
here. This causes the development of the ground stratum to lag behind, 
while it is in advance in the bluff forests. Accordingly we find a sapling 
forest made up largely of cottonwoods. This has not been studied. 



Fig. 174. — One of the fungus 
gnats {Sciara sp.) the larvae of 
which are commonly found under 
the bark of trees, feeding on fungus. 



III. Forest Communities on Rock 

(Station 55) 
The rock exposures near Chicago are not niunerous, and we have 
studied only those at Stony Island. There the bare rock is inhabited 



2i8 DRY AND MESOPHYTIC FOREST COMMUNITIES 

by incidental forms, such as the Carolina locust {Dissosleira Carolina?) 
(40), with occasionally the red-legged locust (Melanoplus femur- 
ruhrum) and the two-lined locust {Melanoplus bivittatus). Under rock 
fragments we took the ground beetle {Anisdaclylus inter punctatus) and 
the common cricket (Gryllus pennsylvanicus) . Hancock (40) states 
that the smooth cockroach {Ischnoptera inaequalis Sauss) and the large 
cockroach (/. major Sauss) occur in such situations. We found the nest 
of a spider {Agelena naevia) attached to one of the loose rocks. 

Other stages have been studied only superficially. In the cracks 
and crevices of rocks and rock piles, shrubs and vines grow and the 
young forest, field, and shrub strata have all the appearance of the 
shrub stage on clay at Glencoe. The animals are for the most part those 
common to thickets. 

IV. Forest Communities on Sand 

In chap, iii, pp. 46, 47, we discussed sand areas and their distribu- 
tion. In chap, viii we noted the series of ponds and ridges with a little 
regarding their origin (pp. 136-40). Their general relations are indicated 
by Figs. 83, p. 137, and 84, p. 139. It appears that the margin of the lake 
may, under conditions of rapid recession, become the margin of an inland 
pond. Under condition of slower recession this belt may be buried and 
hence come to lie beneath such belts as lie farther inland. Since the 
sand areas about Chicago represent all the stages in the development 
of forests, beginning with the bare sand and ending with the beech 
forest, it is my purpose in the remainder of this chapter to follow the 
animal associations and formations of forest development. Some of the 
stages will be taken from till areas, but this is because these stages are 
more extensive than the corresponding stages on the sand deposits. 

The chief stages are the wet sand of the water margin, the middle 
beach, the cottonwoods, the old cottonwoods and pine seedlings, the 
pines, the black oak, the black oak and white oak, the black oak-white 
oak-red oak, the red oak-white oak-hickory, the basswood-red oak- 
white oak-maple in moister places, and the beech and maple. 

I. THE WATER MARGIN ASSOCIATION 

(Stations 56, 58; Table XXXVIII) 

■ One morning early in June, we walked along the beach of Lake 

Michigan for a mile and a half, for the particular purpose of studying 

the animals of the zone within the reach of waves. Animals were few, 

only stragglers of the regular residents which we have noted on p. 181. 



WATER MARGIN 219 

The day was warm and a strong southeast wind was blowing. In mid- 
afternoon there was a small shower and the wind changed to a strong 
northeaster. At 4 p.m. we paid another visit to the beach. The waves 
were rolling moderately high and the beach was covered with a host of 
insects, chiefly alive, though many were dead. The beach was lined 
with live forms crawling away from the water. Often the live ones 
were still clinging to small sticks upon which they had floated ashore 
by the fifties. These insects represented all orders, belonging to various 
habitats near the lake. There were large forest margin bugs, potato- 
beetles, lady-beetles, horseflies, robber-flies, butterflies, water, marsh, 
prairie, and forest inhabitants which had been blown in the lake in the 
forenoon. With them were occasional fish, some with large round scars 
showing the work of the lampreys (166); others that had evidently died 
from other causes. On other occasions dead muskrats, dogs, cats, birds 
of all kinds have been found in these lines of drift (167). On one 
occasion, birds, chiefly downy woodpeckers, were so numerous that 
one could almost step from one to the other, had they been equally 
spaced over the half-mile of beach upon which they were strewn. Need- 
ham (168) has studied the drift and gives an account of the numerous 
beetles that came ashore. 

In a few days after such a storm, one finds the various insects that 
washed ashore either lying dead, or alive under the chips, sticks, and 
carcasses which came with them. Flesh-flies detect the presence of the 
food very quickly, and often come to dead fish inside of ten or fifteen 
minutes (169). These flies belong to the families Sarcophagidae and 
Muscidae. As a result of storms which float the bodies of animals 
ashore from time to time, the flies always find a sufficient quantity of 
decaying flesh to maintain the species. The flies are in competition with 
a large number of scavenger beetles: e.g., a hister (Saprinus patruelis 
Lee.) which feeds on carrion {Stereopalpus badiipennis Lee). Several 
species of rove-beetle complete a partial list of the other scavengers 
usually more or less abundant on the shore. The larvae of Dermestidae 
have been found under the dry remains of fish which had been worked 
over by the carrion-feeders. 

Preying upon these and upon the insects that come ashore are the 
tiger-beetles {Cicindela hirticollis and cuprascens) (151, 170) which pick 
up the flies that they often are able to seize while alighting on the ground. 
They also capture the maggots of the flies when they leave the carrion, 
and the lady-beetles and other small insects which come ashore. Several 
species of the ground beetles and occasional shore bugs (Saldidae) are 



220 DRY AND MESOPHYTIC FOREST COMMUNITIES 

found, while the digger-wasps and robber-flies of the beach farther back 
come here for flies and other prey. The spotted sandpiper picks 
maggots from the bodies of dead fishes. Mr. I. B. Myers states that 
skunks visit the beach in the night and feed upon the drift. 

2. MIDDLE BEACH ASSOCIATION 

(Stations 57, 58, 716) (Fig. 175) 

The belt within the reach of ordinary waves is usually wet. The 
belt a little higher up, farther from the shore, is characterized by more 
permanent residents. From the often wet margin to the first cotton- 
woods is the middle beach (Fig. 175). 

This middle beach is usually dry in summer but is reached by the 
waves of severe storms and often covered by snow and ice to great 
depths during the winter. It is the final lodging-place for the driftwood 
which stops temporarily farther out. This belt arises in the place of 
the preceding through the former being buried by the depositions of 
sand. In digging into the sand here or elsewhere one usually encounters 
wood and other traces of organic matter. 

a) Subterranean- ground stratum. — In the lower places where the 
ground is usually moist, we find the larvae of Cicindela hirticollis (170) 
which live in straight cylindrical vertical burrows about 6 in. deep. On 
higher ground, where there is the beginning of the incipient dunes, are 
the occasional larvae of the white tiger-beetle {Cicindela lepida) and the 
burrowing spider (Geolycosa pikei), which has a burrow similar to the 
tiger-beetles, but larger, and always distinguished by the presence of a 
tubular web at the entrance. Burrowing beneath the sand is the white 
carabid (Geopinus incrassatus Dej . ) and termites or white ants. The latter 

Inhabitants of the Middle Beach 

Fig. 175. — General view showing the line of cottonwoods and the scattered 
driftwood. 

Fig. 176. — The larva of one of the cabbage butterflies (Pieris protodice Bd.); 
found on sea rocket; much enlarged. 

Fig. 177. — Pupa of the same. 

Fig. 178. — A log on the beach; favorite habitat of the termites (Termesjlavipes). 

Fig. 179. — Termites; a, queen; i, nymph of young female; c, worker; </, soldier; 
twice natural size (after Howard and Marlatt, Bull. 4, Div. Ent., U.S. D. Agr.). 

Fig. 180. — The older cottonwoods of the cottonwood belt. 

Fig. 181. — ^The adult white tiger-beetle {Cicindela lepida); twice natural size. 

Fig. 182. — The burrow of the larva of the white tiger-beetle. 



MIDDLE BEACH 



221 




Inhabitants of the Middle Beach 



22 2 DRY AND MESOPHYTIC FOREST COMMUNITIES 

feed on decaying wood (Fig. 178) and make their way to the under side 
of wood lying on the beach (Fig. 179). The bank swallow often nests 
in the sides of vertical sandbanks. Under the driftwood we find the 
scavengers and predatory species of the preceding belt. They spend 
their time here when the beach is not well covered with food. The 
sand-colored spider (Trochosa cinerea) (138) is a regular resident. The 
common toad finds shelter beneath the driftwood during the day, going 
forth in search of food at night. After sleeping near the beach one night 
we found the sand about where we had lain crossed and recrossed by the 
tracks of the toads and other smaller animals, such as beetles, spiders, 
etc. The toad finds food abundant near the shore. The white-footed 
mouse occasionally nests here under the largest driftwood. The spotted 
sandpiper and piping plover nest here occasionally. 

h) Field stratum. — There are occasionally very young seedling 
cottonwoods. Sea rockets and some other plants grow in this belt. 
Occasionally we find the larvae of a cabbage butterfly (Pieris protodice 
Bdv.) (171) on the sea rocket (Figs, 176, 177). There is no shrub or 
tree stratum. 

3. THE WHITE TIGER-BEETLE OR COTTONWOOD ASSOCIATION 

(Stations 57, 58, 59; Tables L, LVI, LVII) 
(Fig. 180) (115) 

This begins with the line of young cottonwoods which we see in 
Fig- 175- The beach belt sometimes overlaps it because the large 
driftwood is sometimes mixed with the cottonwoods. The cottonwood 
belt is underlaid by the two preceding, and has succeeded them. 

a) Subterranean-ground stratum. — Here the white tiger-beetles (Figs. 
181, 182) reach their maximum abundance and the openings of their 
cylindrical burrows are numerous; the termites continue wherever there 
is wood for them to feed upon; the burrowing spider is commoner 
here than in the preceding zone (172). This is pre-eminently the zone 
of digger-wasps (173). Here the holes of Microbembex monodonta 
(Fig. 183) are numerous. This species is somewhat gregarious, the bur- 
rows usually being in groups. They probably store their nests with flies 
secured often from the beach. Another larger bembex (Figs. 184, 185) 
{B. spinolae) also stores its nest with flies. Anoplius divisus, the 
black digger, stores its nest with spiders. The velvet ant {Mutilla 
ornativentris) is present. Dielis plumipes appears in May and lays its 
eggs in the sand. 

The robber-flies {Erax) (Fig. 186) (165) (Promachus vertebratus) (Fig. 
187) are common; their larvae live in the sand as parasites on other 



COTTONWOOD ASSOCIATION 



223 



species. Some bee-flies (Exoprospa) (Fig. 188) lay their eggs at the 
entrances of the burrows of Microhembex. The roots of the beach grasses 
are probably attacked by the larvae of snout-beetles (Sphenophorus) 
(Fig. 189) (174) of which several species are very common in the vicinity. 
The white grasshopper {T rimer otro pis maritima) (40) and the white tiger- 
beetle (Cicindela lepida) are most characteristic. The long-horned 
locust {Psinidia fenestrcdis) (Fig. 189) occurs commonly. 

b) Field stratum. — ^The field stratum is made up of animals that 
occupy the gns>es, sagebrush, and a few other xerophytes. Animals 




Digger- Wasps of the Cottonwood or White Tiger-Beetle Association 

Fig. 183. — Photograph of a number of the burrows of one of the digger-wasps 
(Microbembex monodonta) at Pine, Ind. 

Fig. 184. — A digger-wasp (Bembex spinolae); about twice natural size. 

Fig. 185. — A sectional drawing of a burrow of the digger-wasp (Bembex spinolae)', 
reduced (after the Peckhams, Wis. Geol. and N. H. Surv.). 



are few. An occasional red-legged locust {Melanoplus femur-rubrum) 
occurs here. Midges, mosquitoes, and the flies which breed on the beach 
rest on the leeward side of the grasses (169). Various native sparrows 
are common in fall, feeding on grass and weed seeds. 

c) Shrub stratum. — On the young cottonwoods we find the crab- 
spider {Philodromus alaskensis), often with its appendages stretched out 
on the petiole or midrib of a leaf. The animals feeding on the cotton- 
wood here are few. In early spring the willow blossoms are frequented 



2 24 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



by pollen-gathering insects {Andrenidae, Apidae, syrphus flies, etc.). 
The kingbirds feed on these insects; one article of their diet, the robber- 
flies, is always common. A chrysomelid beetle {Disonycha quinquevittata) 
commonly feeds upon the willow. The cherry is attacked by aphids 




Fig. i86. — A robber-fly {Erax sp.); 3 times natural size (after Williston). 




187 



Fig. 187. — Robber-fly {Pro- 
machus verlebratus Say); natural 
size (after Washburn from Willis- 
ton). 

Fig. 188. — A bee-fly {Exoprosopa 
sp.); 1 1 times natural size (from 
Williston after Kellogg). 



which attract the Coccinellidae, and the syrphus flies, 
eaten by many birds. 



Cherries are 



COTTONWOOD ASSOCIATION 



225 



d) Tree stratum. — 'The cottonwood is attacked by many borers. 
The most characteristic is Plectrodera scalator, which is not common. 
There are few leaf-feeders excepting two gall aphids; the petiole gall is 
due to the work of Pemphigus populicaulis, and the terminal gall to 
Pemphigus vagabundus (137). These occur on the cotton woods along 
the lake rarely, being more abundant farther inland, where they are 
protected from the severity of winter. The osprey nests in trees, and the 
tree-swallow in the dead ones. 

We have noted that this association often arises through the burying 
of the preceding one. Deposition of 
sand is the chief cause of succession 
up to this point. When cottonwoods 
and grasses begin to grow and digger- 
wasps begin to burrow, organic mat- 
ter is continually added to the soil. 
The grasses die down from time to 
time, the roots and leaves of the 
shrubs and other plants add himius. 
The myriads of digger-wasps which 
go elsewhere (probably commonly to 
the beach) for the animals with which 
to store their nests add a large amount 
of organic matter at a depth of a few 
inches. The grasses bind the dune 
sand; the conditions become favorable for other plants 
stage the bunch-grass and seedlings of pines appear. 




Fig. 189. — ^The long-horned locust 
{Psinidia fenestralis) (after Lugger). 



At such a 



4. TRANSITION BELT 

(Station 58; Table L) (Fig. 190) (115, 170) 

The stage of mixed pine seedlings, old cottonwoods, and the begin- 
ning of the bunch-grass constitutes a well-marked belt. Along the 
shore, from Indiana Harbor to Gary, there was formerly a ridge upon 
which the lakeward-facing side supported the typical community of the 
cottonwoods and the landward side the transitional belt. When one 
crosses to the landward side of such a ridge he notes a change in the 
animals. The white tiger-beetles and the maritime grasshopper are 
practically absent. Digger-wasps are abundant. The larvae of the 
large tiger-beetle {Cicindela formosa generosa) (Figs. 1 91-193) with their 
pits and crooked holes are added, but they rarely invade the dense pine 
areas. Another grasshopper (Fig. 194) {Melanoplus atlanis) and an 



226 



DRY AND MESOPHYTIC FOREST COMMUNITIES 




Fig. 190. — The cottonwood and young pine area at Buffington, Ind. 
Fig. 191. — The burrow of one of the tiger-beetles resident here. 
Fig. 192. — The same opened, showing the stove-pipe form of burrow opening 
into the side of the pit shown in Fig. 191. 

Fig. 193. — The adult beetle {Cicindela formosa generosa). 



PINE ASSOCIATION 227 

occasional M. angustipennis are added (40). The burrowing spider 
(Geolycosa pikei) (Fig. 200, p. 230) continues in the open places. 

5. THE CICINDELA LECONTEI OR PINE ASSOCIATION 

(Stations 57, 58, 59; Tables L, LI, LVI, LVIII) (Figs. 201) (115, 170) 
a) Subterranean-ground stratum. — Here we find the larva of the 
bronze tiger-beetle {Cicindela scutellaris lecontei) (170), with its straight, 
cylindrical burrow. Several digger-wasps of the earlier stage are 
recorded as continuing. The ant {Lasius niger americanus) nests 
beneath the sand and was seen swarming in early September. The 
burrowing spider continues and an occasional cicada lives deep beneath 
the sand. The six-lined lizard (Cnemidophorus 6-lineatus), the blue 
racer, and the pond turtle {Chrysemys marginata) all bury their eggs 
beneath the sand. There is an occasional thirteen-lined ground squirrel 




Fig. 194. — The lesser migratory locust (Melanopliis atlanis) (after Lugger) . 

{Citellus ij-lineatus) (162), though it is never common. The surface 
of the ground is frequented by the adults of the tiger-beetles, digger- 
wasps, the si.x-lined lizard, and the blue racer (157). The grasshopper 
of the transition belt continues and two others are added, so that we 
have the long-horned locust, the narrow-winged locust, the lesser locust, 
the mottled sand-locust (Sparagemon wyomingianum Thom.), and sand- 
locust (Ageneotettix arenosus) (40). The ruflfed grouse nests here occa- 
sionally. 

b) Field stratum. — Arabis lyrata is a common herb. ShuU (175) 
found that the larva of a cabbage butterfly feeds upon this. He 
watched a larva crawl on one of the bunches of bunch-grass for six 
hours before it began to spin the bed of silk preparatory to pupating. 
This was about 2 in. above the ground. Midges and mosquitoes are 
common and dragon- and damsel-flies are nearly always in evidence 
resting on the grasses and herbs and picking up the midges and mos- 
quitoes while on the wing. Occasional Monardas support crab-spiders 
which resemble the blossoms closely (Dictyna foliacea). The flowers 
are visited by bees and flies. 



228 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



c) Shrub stratum. — Here we have the young pines, the juniper, and 
the willows. From the evergreens we secured several spiders (Philo- 
dromus alaskensis, Dendryphantes octavus, Theridium spirale, and 
Xysticus formosus) (172), and with them sometimes an assassin-bug 
(Diplodius luridus). On the willows are some characteristic willow- 
feeders, but they appear to prefer the more mesophytic depression 
shrubs. 




Inhabitants of the Pine 

Fig. 195. — The nest of the kingbird {Tyrannus tyrannus Linn) in a pine tree. 
The nest is made from the string of a fisherman's net. 

Fig. 196. — ^The pitch mass of the pitch-moth (Evetria comstockiana?); twice 
natural size. 

Fig. 197. — The larva removed from the mass. 

Fig. 198. — ^The larva of the pine engraver beetle dps gr audi colli s)', much 
enlarged. 

Fig. 199. — ^The adult of the same, from Finns banksiana. 



d) Tree stratum. — -The pine is attacked by many borers and few 
leaf- feeders. Of the borers several broad-headed grubs have been taken. 
The bark beetle {Ips [Tomicus] grandicollis) (Figs. 198, 199) (137) is 
common under the bark of dead and dying trees, especially on the north 
side, where the trees stand unprotected. The twigs are attacked by the 



BLACK-OAK ASSOCIATION ' 229 

pitch-moth {Evetria comstockiana?) (Figs. 196, 197) (137) which feeds 
on the new shoots, covering itself with a tent made of pitch and its own 
excreta. About the bases of the needles, or where pitch is exuding, we 
often find small larvae resembling Cecidomyiidae fly larvae, but we have 
found no pitch-midges, chrysomelid flea-beetles, spittle insects, or other 
enemy of the eastern hard pines which grow in thicker stands. More 
careful study of these trees at frequent intervals throughout the grow- 
ing season would probably greatly increase the list of both borers and 
leaf-feeders. 

The hairy and downy woodpeckers nest in the hollow trees. Their 
deserted holes are later used by the black-capped chickadee and the 
screech owl. Farther north the pine grossbeak and crossbill nest in the 
live pines. The golden-crowned kinglet and the black- throated, green, 
and pine warblers are abundant here during the migration period. They 
nest in the pines farther north, and, according to Butler (108), not infre- 
quently at the head of Lake Michigan. Dr. Stephens photographed a 
kingbird's nest made from cord from a fisherman's net (Fig. 195). 

The pines prepare the way for the oaksj which appear first as seed- 
lings, usually becoming more dense with time and finally crowding out 
the pines. 

Moving dunes and "blowouts" (depressions in the sand made by 
wind) are common at the head of Lake Michigan. The latter vary 
from a few feet square and a few inches in depth to some scores of feet 
in depth and diameter. Dunes, hundreds of feet high, move from place 
to place. On these the bare-sand conditions of the cottonwood and pine 
associations occur in areas generally dominated by black oak. Here con- 
tinue the animals of these two belts, with the possible exception of the 
maritime locust. The typical black-oak forest always possesses these 
"blowouts," but surrounding them and under the trees we note the 
typical herbaceous and shrub growth, and it is with this and the oaks 
that we are next concerned. 

6. THE ANT-LION OR BLACK-OAK ASSOCIATION 

(Stations 57, 60, 61, 62; Tables L, LII, LVI, LIX) 
(Fig. 202) (115, 170, 176) 
Among the black oaks are open spots of relatively stable sand. 
These small areas may possess some of the same species as the pine areas, 
but other species give them individual character. In the black-oak 
stage proper, bare sand is limited. The bronze tiger-beetle (Cicindela 
scutellaris lecontei) (Fig. 204) which is parasitized by the larva of a bee- 
fly (Spogostylum anale) (Fig. 205) is abundant (151a.) 



230 



DRY AND MESOPHVTIC FOREST COMMUNITIES 




Representatives of ihi, I'imc and Black-Oak Association 

Fig. 2CX>. — The burrow of a ground spider (Geolycosa pikei) ; about natural size. 
Fig. 20I. — General view in the pines. Fig. 202. — General view among the oaks. 
Fig. 203. — The ant-lion and the pupa and adult into which it transforms. 
Fig. 204. — The opening of the burrow of the bronze tiger-beetle {Cicindela 
scutellaris lecontei) ; natural size. 

Fig. 205. — The bee-fly {Spogostylum anale); twice natural size. 



BLA CK-OA K A SSOCIA TION 



231 



a) Subterranean- ground stratum.— Seversd digger-wasps and para- 
sites not found in the earlier stages occur among the more closely placed 
vegetation here {Epeolus pusillus, a parasite, Specodes dichroa, and Ody- 
nerus anormis). A megachilid or leaf-cutter makes a nicely matched 
thimble-shaped cell. This cell is placed at the end of a burrow about 
2 in. below the surface of the sand. The burrow is about 4 in. long. The 
leaf-cutter is attacked by a parasitic bee {Coeloixys rufitarsus) which 
lays its eggs upon the larval cell. One sunny day we found the digger- 
wasp {Ammophila procera) (173) with a black-oak caterpillar {Nadata 




Representatives of the Black-Oak Community 

Fig. 206. — One of the solitary wasps {Ammophila procera), with the oak-feeding 
larva {Nadata gibbosa) , which it has carried to a point near its nest and laid upon the 
ground; 15 times natural size. 

Fig. 207. — Female crab spider {Misumessus asperalus) (after Emerton); enlarged. 

Fig. 208. — Male of same. 

Figs. 2090, 2096. — The flatbug {Neuroclenus simplex) which lives under the bark 
on the dead oaks. 209a is a side view, much enlarged. 



gibbosa) (Fig. 206) (137). When first observed, the larva was lying on 
the ground and the wasp was moving about some 6 in. away. As we 
approached, the Ammophila, apparently disturbed, seized the large 
caterpillar and ran into the adjoining vegetation, where it was captured. 
All the forms mentioned as breeding beneath sand, feed at the surface 
of the soil or upon the vegetation. In open places among the black 
oak we find the same grasshoppers as in the earlier stages. The hog-nosed 
snake (40) is common; it spreads and flattens out its head when dis- 
turbed; when handled roughly it often goes into a death feint, such as 
the oriental snake-charmers produce in their poisonous snakes by pres- 



232 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



sure on the back of the neck. In this state it can be handled as if dead, 
laid in any position, or tied into a knot. The only movement it persists 
in making is that of turning its ventral side uppermost. Ant-lions (Fig. 
203) are very rarely found at the south end of Lake Michigan, except 
in the oak belt. They make cylindrical conical pits in the sand (177, 
179). The most characteristic species under the bark of fallen oaks is 
the flatbug (Fig. 209). 

h) The field stratum. — This stratum is dominated by many flowering 
plants, such as Monarda, etc. The addition of a host of insects and 
spiders not present in the earlier conditions is noticeable. Of the grass- 
hoppers we add six species (Scudderia texensis, Xiphidium strictum, 

Chloealtis conspersa, 
Schistocerca rubiginosa, 
Oecanthus fasciatus, and 
Conocephalus ensiger) 
(40). 

The andrenid bees 
{Agapostemon splendens) 
and various robber-flies 
are numerous. On the 
Monarda the honey-bees, 
bee-flies (Fig. 210), bum- 
blebees, and spiders (Mis- 
umessus asperatus [Figs. 
207, 208], Dictynafoliacea, 
Agriope trifasciata, and 
Epeira sp.) are common. 
The blueberry is com- 
monly one of the small herbs of the field stratum and upon it we find 
several characteristic galls. 

c) Shrub stratum. — This stratum is made up of the choke-cherry, 
young oaks, rose, etc. The shrub which has been given most attention 
is the choke-cherry. On this the lacebugs (Fig. 211) are often numerous; 
the puss caterpillar (Cerura sp.) (163) sometimes occurs. This cater- 
pillar has a pair of long projections at the posterior end. When disturbed 
it extends and waves these projections and thus makes of itself one of 
the most fantastic of our caterpillars. 

Grapevines are not uncommon on the dunes and we often find a 
curious red petiole gall on them, which is not common elsewhere. The 
large fleshy larvae of the achemon sphinx (163) are sometimes taken. 




Fig. 210. — A bee-fly {Bombylius major Linn.) 
(from Williston after Lugger) . 



RED-OAK ASSOCIATION 



233 



d) Tree stratum. — The black oak (137) is attacked by a large, light- 
green larva which has a narrow yellow stripe down its back {Nadata 
gibbosa). It is also attacked by several slug caterpillars which we have 
been unable to identify. The beautiful prominent larva with a saddle 
of red is occasionally taken. Commonly feeding on the juices of 
the leaves are several species of leaf-hopper {Typhlocyba querci var. 
bifasciata), the common grapevine leaf-hopper, and the white black- 
marked leaf-hopper which occurs also on the hickory. The oak tree- 
hopper {Telemona querci) (Fig. 212) is a common leaf-sucker. Squirrels 
are probably occasional visitors as they come to feed upon acorns. The 
acorns are also often attacked 
by weevils. 

In such a set of graded 
forest stages as we are dis- 
cussing it is possible to note 
many stages. The stage 
which we have just de- 
scribed passes more or less 
rapidly into the next, the 
rate of change depending 
upon the height above 
ground water and the degree 
to which the sand is shifted 
by the wind. On the parallel 
ridges, the next and perhaps 

most notable forest stage contains white oak and red oak and is found 
in places on the ToUeston, Calumet, and Glenwood beaches. The 
ecological age of the forest is determined by the height above ground 
water. Ridge 93, inside the Tolleston Beach, is low and forest has 
progressed as far as on the older beaches. 

V. Mesophytic Forest Formation (115, 170) 

•I. HYALIODES OR BLACK OAK-RED OAK ASSOCIATION 

(Station 63, also near stations 27 and 65; Tables L, LIII,LVI, LIX) (115) 

This is represented at several points. 

a) Subterranean-ground stratum. — In this stratum the woodchuck 
or groundhog is common (142). Earthworms have begun to appear. 
The root-borer Prionus (155) and several species of ants are common, 
while the numerous digger-wasps of the earlier stage have largely dis- 
appeared. The depressions which contain water in spring are typical 




Fig. 211. — The lacebugs common on the oak 
and wild cherry in the dune region (Corythuca 
arcuata) (from Washburn after Comstock): 
a, adult; h, young. 



234 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



forest temporary ponds. Beneath the leaves and wood are snails 
(Zonitoides arboreus), millipedes (Polydesmus sp.), and centipedes (Litho- 
hius sp.), and in dry weather Polygyra Ihyroides and muUilineata. 
Ground beetles and rove-beetles are common. One finds Cicindela 




Fig. 212. — The oak tree-hopper {Telamona querci) (after Lugger). 

sexguttata, the green tiger-beetle, here rarely; it is much commoner in 
later stages, however. 

In the decaying logs and stumps are darkling beetles (156), numerous 
wireworms (Elaleridae) , and myriopods. Sometimes fungus-feeding 
beetles (Diaperis hydni and Eustrophus tormentosus) are present in 

numbers. Ants are also often 
abundant. Carpenter ants are 
common. The aphid housing 
ant (Lasius umbratus subsp. 
mixtus var. aphidicola) is some- 
times abundant. In autumn 
certain galleries in the wood 
are crowded with woolly aphids 
which are the so-called "cows" 
which the ants house for the 
winter. 

b) Field and shrub strata. — • 
In moist weather the snails (Polygyra) mentioned above are common 
on the herbaceous vegetation, while the tree-frogs {Hyla versicolor and 
pickeringii) (139) are common, and spiders are numerous. 

c) Tree stratum. — The oaks (137) are affected by many of the same 
species as in the earlier stages. The tree-frog is sometimes found in the 





Fig. 213. — ^The oak plant-bug {Hydiodes 
mtripennis) (from Washburn after Riley): 
a, young; h, adult. 



HICKORY ASSOCIATION 



235 



trees and the walking-stick {Diapheromera femorata) (40) is common. 
One of the most characteristic galls is the oak-seed gall (Andricus semi- 
nalor), particularly abundant on white oak of this stage and not common 
later. Galls are very common on the white oak. The predatory capsid 
(Hyaliodes vitripennis) (Fig. 213) is usually present on the bark of the 
oaks, and is often in company with book-lice (Psocus). The squirrels, 
chipmunks, and birds of this association are similar to those of the next 
stage and will be discussed there. 



1 V 



t-^.' 



'-^ ^«.^{v! 



'^ 


f^l^H^t 



Fig. 214. — General view of the white-oak red-Oak hickory forest (Glencoe). 



2. 



THE GREEN TIGER-BEETLE OR WHITE OAK-RED OAK-HICKORY 
ASSOCIATION 



(Stations 56, 64, 65; Tables LIV, LXI) (Fig. 214) 

This is the climax forest of the savanna region. The groves are 
largely made up of it. Though somewhat disturbed in localities where 
studied, it presents some variations. Areas along the north shore contain 
considerable basswood. The Higginbotham woods at Gaugars (Fig. 
215) contain very few hickories and many maples; this type stands in 
closer relation to flood-plain and marsh forests than those discussed 
later. The woods at Suman are well invaded by beech and maple 
seedlings and represent the latest stages of this forest. It is thought 



236 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



best to treat all phases together, simply mentioning the points of 
difference. 

a) Subterranean-ground stratum. — Earthworms, borers in the roots of 
trees, and cicada nymphs are numerous. The wolf, groundhog, and 
the red fox {Vulpes fulvus Des.) nest in burrows. The latter brings 
forth from four to nine pups in early spring. 

Consocies of the under side of leaves and wood: The camel cricket 




A Mesophytic Forest 

Fig. 215. — General view of the Higginbotham woods near New Lenox, 
of the flood-plain oak-hickory type. 



Woods 



(Ceuthophilus) (Fig. 216), young cockroaches, the short- winged grouse 
locust {Tettigidea pennata Morse), and the yellow-margined millipede 
(Fontaria corrugate) (Fig. 218) are most characteristic under the leaves. 
The large round millipede {Spiroholus marginatus) (Fig. 217) is common. 
Snails and slugs are numerous, several species {Polygyra pennsylvanica 
[Fig. 219], P. profunda [Fig. 220], Zonitoides arboreus, Pyramidula aller- 
nata [Fig. 221], Pyramidula solitaria [Fig. 222], Agriolimax campestris 



HICKORY ASSOCIATION 



237 



Circinaria concava [Fig. 223]) are usually common and Polygyra albolabris 
is characteristic of the more mesophytic parts. 

The ruffed grouse, oven-bird, and woodcock nest on the ground. 
The timber rattlesnake (Crotalus durissus Harlan) formerly occurred 
in rocky situations (22). The four-toed salamander {Hemidactylium 
scutatutn Schl.) is found locally (22). The white-footed wood-mouse 
(Peromyscus leucopus noveboracensis Fisch.) builds a nest under fallen 




216 



;-— ■^^ 



218^ 





# ^ 



219 220 



223^ 



222 



Inhabitants of a Mesophytic Forest 

Fig. 216. — The wingless wood locustid (Ce«</;o/i/tz7?«) ; enlarged. 

Fig. 217. — The common millipede (Spiroholus marginatus); natural size. 

Fig. 218. — Another millipede (Fowaria corrwgfl^s) ; natural size. 

Figs. 219-223. — Snails from the woods. 219, Polygyra pennsylvanica Green; 
220, Polygyra profunda Say; 221, Pyramidula solUaria; 222, Pyramidula alternata; 
223, Circinaria concava. 

( 
logs and stumps (21). The gray fox {Urocyon cinereoargenteus Mull.) is 
more dependent upon heavy.timber than the red fox (21). The cotton- 
tail (21), which belongs to forest edge, frequently winters in the woods. 

The bear was formerly common, nesting under fallen trees and feed- 



238 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



ing extensively on the berries. The timber wolf had its den in similar 
places, though often burrowing into the ground. In Central Illinois 
moles are common residents of groves near cultivated lands. The 
Virginia deer (OdocoUeus virginianus Bodd.) was formerly common and 
was preyed upon by the wolves and panthers. The latter sometimes 
leaped upon its prey from the branches of the trees (142). 




Inhabitants of Trees and Shrubs 

Fig. 224. — The spiny spider (Acrosoma gracilis), legs wanting (after Emerton). 

Fig. 225. — Another spiny spider {Acrosoma spinea) : a, female; b, male; c, young 
(after Emerton.) 

Fig. 226. — Acorn weevils: a, dorsal view; b, side view (after Riley, U.S. D. Agr.). 

Fig. 227. — A red-oak sawfly larva. 

Fig. 228. — ^A female walking-stick on the trunk of a tree, with a caterpillar 
{Halisidota sp.) on the bark above. 



Consocies of logs (in wood and under bark) : There is a regular suc- 
cession of forms which affect any one species of the trees of the forest. 
The earlier forms usually attack the trees while they are standing, and 
accordingly belong more properly to the tree stratum. When the bark 



HICKORY ASSOCIATION 



239 



has become loosened, however, we find practically all the small mverte- 
brates recorded on the ground. The small andrenid bees {Augochlora 
Pura) build small cells under the bank and fill them with pollen. One 
egg is laid in each cell (July), and the larva feeds upon the pollen. 
Sowbugs (Cylisticus convexus and Porcellio ralhkei) and centipedes 
(Lithobius, Lysiopelalum lactarium, and Geophilus rubens) are common. 
Numerous beetles burrow into the wood or feed on fungi under bark. 
Some of the chief borers are (Cerambycidae) Prionus and Orthosoma 
brunneum, and also Passalus cornulus. The large slug (Philomycus 
carolinensis) is common. 




Fig. 229. — The oak twig pruner {Elaphidion villosum Fabr.) (after Washburn) 
{17th Rept. Minn. Agr. Exp. Sta., p. 165, Fig. 36). 



b) Field stratum. — After rains the slugs and snails, especially the 
young, crawl upon the vegetation. Several flies are common (Sapromyza 
philadelphica) . A leaf -hopper {Scaphoideus auronitens), a damsel-bug 
(Reduviolus annulatus), the shield grasshopper {Atlanticus pachymerus) , 
and a spider {Theridium frondeum) have all been recorded. 

c) Shrub stratum. — ^Many spiders build their nests and webs in this 
stratum. Epeira domicilorum was found with a nest of leaves drawn 
together adjoining its web. Epeira gigas, the large yellow spider, builds 
near open places, on high shrubs. The web is a large orb, the nest in a 
convenient group of leaves near the upper side. 



240 



DRV AND MESOPHYTIC FOREST COMMUNITIES 



Acrosoma gracilis (Fig. 224) (138, 172) commonly stretches its web 
between the trunks of two small trees which stand about 4 ft. apart. 
The center of the orb is commonly about 6 ft. above the ground ; it is 
nearly vertical. The spider usually hangs near the center. 




The Standing Dead Oak and Inhabitants 

Fig. 230. — Showing the larva, pupa, and adult of the large wood-eating beetle 
(Passalus cornutus) ; about natural size. 



Acrosoma spinea (Fig. 225a, h, c) (138, 172) commonly places its web 
in a nearly horizontal position on the upper side of leaves. The spider 
clings, ventral side up, on the lower side of the web. The web is 
usually from i to 3 ft. from the ground. The spider often falls to the 
ground when disturbed. The two Acrosomae are confined to mesophytic 
forests of the oak-hickory type. They have not been recorded north of 
Chicago. 



HICKORY ASSOCIATION 



241 



A wasp (Polistes) builds its comb of wood pulp on the under side of 
the leaves. Various larvae and beetles feed upon the leaves of the 
undergrowth. A bug {Acanthocephala terminalis), a leaf -beetle (Calli- 
grapha scalaris), the fork- tailed katydid (Scudderia furcata), the round- 
winged katydid (Amblycorypha uhleri Brun.) (40), and various other 
insects have been secured from shrubs, especially in slight open- 
ings. The black snake (22) (now rare) often rests on bushes in such 
forests. The black and yellow warblers and woodthrush nest on the 
shrubs. 







^' 'HW;:^-*- , ■^■"^i.f. M-i 



The Standing Dead Oak and Inhabitants 

Fig. 231. — The successor of Passalus {Philomycus carolinensis) . 
Fig. 232. — ^The work of a carpenter ant in the same tree. 



d) Tree Stratum. — 'The walking-stick (Fig. 228) (Diapheromera femo- 
rata) (40) is common on the tree trunks in the fall. The red oak 
supports the tree cricket (Oceanthus angustipennis) , the stinkbug 
(Euschistus tristigimus) , and the oak-leaf beetle {Xanthoma lo-notata). 
Felt records several insects injurious to the red oak alone. From the 
white oak we have taken the katydid {Cyrtophillus perspicillatus) , the 
larvae of sawflies (Fig. 227) and moths {Anisota senatoria), and various 
galls. Several weevils (Fig. 226a, b) occur on acorns, and the twig- 



242 



DRV AND MESOPHYTIC FOREST COMMUNITIES 



borer (Elaphidion villosum) (Fig. 229) in the twigs. The hickory 
supports many larvae, including a Phylloxera which forms galls on the 
leaves (see Fig. 277, p. 273). 

The red-tailed and red-shouldered hawks, the red-headed wood- 
pecker, the wood-pewee, the crow, bluejay, robin, and bluebird nest in 
the trees. The panther and wildcat {Lynx rufus) were former residents. 




Fig. 233. — The beech woods. Note small amount of undergrowth. 

Dead standing oaks are attacked by a series of animals. As soon 
as the wood begins to soften, the four-legged larva of Pas solus cornutus 
often appears. This is succeeded by slugs and ants (Figs. 230, 231, 232). 

2. WOOD-FROG OR BEECH AND MAPLE FOREST ASSOCIATION 

(Stations 70, 71, 71a, 716; Tables LV, LXII) (Fig. 233) 
The coming of this stage is indicated by the presence of seedlings 
of beech and maple in the oak-hickory forest, e.g., at Suman, Ind. 



BEECH ASSOCIATION 243 

a) Subterranean-ground stratum. — Earthworms continue; an occa- 
sional groundhog has been seen, though they are probably much less 
common here than in the preceding stages. The stratum appears less 
closely inhabited than the preceding. Under leaves are found scattered 
snails, centipedes, etc. The yellow-margined millipede {Fontaria cor- 
rugate) is most common. There is an occasional Centhophilus. We 
have found no other Orthoptera in beech woods proper, though 
Hancock records several (40, p. 422). Animals are more abundant 
under logs than under leaves. Here we find the large slug (Philomycus 
carolinensis) and several species of snails which, though characteristic, 




Figs. 234-240. — Some beech woods snails: Ground stratum; 234, Pyramidula 
perspectiva; 235, Polygyra inflecta; 236, Polygyra palliata; 237, Polygyra fraudulenta; 
238, Polygyra oppressa; 239, Pyramidula solitaria, adult; 240, Polygyra albolabris. 

are not abundant. These snails are Polygyra inflecta (Fig. 235), 
oppressa (Fig. 2^8) ^ fraudulenta (Fig. 237), palliata (Fig. 236), albolabris 
(Fig. 240), Pyramidula solitaria (Fig. 239), alternata, and perspectiva 
(Fig. 234), and Zonitoides arboreus. These species of Polygyra are 
distinguishable by the presence of characteristic "teeth" in the 
entrance of the shells. The large spider {Dolomedes tenebrosus) and 
millipede (Spirobolus marginatus) occur. Crane-fly larvae, ground 
beetles (Plerostichus adoxus), a centipede {Geophilus rubens), the wood- 
frog {Rana sylvatica) (Fig. 241) (139), and the red-backed salamander 
{Plethodon cinereus) (152) (Fig. 242) are common and characteristic. 



244 



DRV AND MESOPHYTIC FOREST COMMUNITIES 



Pickering's tree-frog is sometimes abundant. The oven-bird nests on 
the ground. 

b) Field and shrub strata. — The field stratmn is very poorly devel- 
oped in summer, herbaceous plants being most abundant in early spring. 
The pawpaw supports the zebra swallowtail butterfly (Papilio ajax 
Linn.), and the spice-bush the green-clouded swallowtail (Papilio iroilus 
Linn.). In the shrubbery in general we have taken snout-beetles, leaf- 
beetles, etc., usually as incidental occurrences, however. A lacebug 
(Gargaphia tiliae), which has been recorded on basswood, and several 





Representatives of the Wood-Frog Association 
Fig. 241. — ^The wood-frog (Rana sylvatica); about natural size. 
Fig. 242. — ^The red-backed salamander {Plethodon cinereus); about natural size. 
Fig. 243. — ^The remains of a fungus found growing under a pile of logs in moist 

woods (not beech), and the fungus-feeding beetle {Tritoma unicolor Say); about 

natural size. 



species of bugs and beetles have also been taken, but all are incidental 
and of widely distributed species. 

c) Tree stratum. — On trunks, shelf fungi are common and are usually 
inhabited on the under side by the tenebrionid beetle (Boletotherus 
bifurcus) (156), a curious rustic beetle. Few characteristic species have 
been taken from the trees. From the bark of the trunk we have taken 
harvestmen (Oligolophus pictus and Liobunum nigropalpi) and from the 
twigs woolly aphids {Pemphigus imbricator) (Fig. 245). There is an 
occasional lo larva on the leaves (Fig. 244). 

The great crested flycatcher, wood-pewee, bluejay, scarlet tanager, 
red-eyed vireo, and woodthrush nest in the low trees and on the lower 



BEECH ASSOCIATION 



245 



levels of the higher trees. Little is known of the mammals of the beech 
and maple forest. Deer, bears, wolves, foxes, hares, etc., appear to 
prefer forests with more undergrowth and herbaceous vegetation. 
Squirrels are fond of beechnuts, and are probably the chief resident 
mammals. The fox squirrel, gray squirrel, red squirrel, and other mam- 
mals of the preceding stages doubtless occur. 

d) Consocies of the decay of a beech. — Succession: Any tree which 
is torn down by the wind or lightning is attacked by a series of borers, 




Leaf- and Twig-Feeders 

Fig. 244. — The nest of an lo caterpillar in the beech leaves; reduced. 

Fig. 24.5. — Woolly aphids {Pemphigus imbricalor Fitch) on the twig of the beech; 



reduced. 



etc., each one helping to prepare the way for those that follow. To 
illustrate the general principles, the succession of animals in any species 
of tree might be presented. We have chosen the beech. 

According to Felt (137), living beeches are commonly attacked by the 
red-horned borer {Ptilinus ruficornis Say) which bores into the bark 
and wood, and another borer {Anthophilax attenuatus Hald,) which lays 
eggs in the galleries thus formed. We have examined four stages of the 
decay of beech trees. 



246 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



First stage: Tree freshly fallen (Fig. 246). Only forms recorded are 
the apple-tree engraver beetle {Pterocyclon mali Fitch) (Fig. 247) which 
makes galleries in the solid wood. 




Succession in the Beech Log 

Fig. 246. — The freshly fallen beech. 

Fig. 247. — The first borer to enter the fallen tree {Pterocyclon mali Fitch); 
greatly enlarged (from Lugger after U.S. Dept. Agr.). 

Fig. 248. — The partially decayed beech. 

Fig. 249. — Closer view of the same showing the burrows of the different wood- 
boring larvae in the softened wood. 

Fig. 250. — Shows the last stage in the decay of the beech. 



CAUSES OF SUCCESSION 247 

Second stage (Fig. 248): Bark loosened; wood still solid or barely 
softened. Under the bark were the Aa.ttened Pyrochroidae larvae, the 
small snail {Zonitoides arboreus), a few of the four-legged larvae of 
the passalid {Passalus cornutus), many larvae of fungus-gnats {Myceto- 
philidae), and a single specimen each of the beetle {Penthe pimelia) and 
the slug {Philomycus carolinensis) . None of these were abundant. 
The flattened beetle larvae were most characteristic. 

Third stage (Fig. 249): The wood is thoroughly softened and the 
bark generally loosened. Here the animals present in the earlier stage 
are increased in numbers. The passalid larva is more abundant. 
Slugs are numerous. Snails (Pyramidula alternata) are found in such 
situations as are large enough for them to enter. Fungus-eating beetles 
are present {Megalodacne heros Say). A click-beetle larva (Tharops 
ruftcornis Say) bores into the softened wood. 

Fourth stage (Fig. 250): The bark fallen off; the log a mere mass of 
rotten wood. Such a log is only shelter for the regular inhabitants of 
the forest floor which we have already enumerated on the preceding 
pages. 

VI. General Discussion 

A study of the tables shows several points of interest. Take first 
the ground stratum. Beetles which live under decaying wood are 
common on the beach where the decaying wood is common, but are 
absent through the Cottonwood, pine, and black-oak stages. They 
appear again with the fallen leaves and moist logs of the black oak-red 
oak stage. Vegetation in itself is not directly important. Moist 
decaying wood is common, both on the beach and in the woods. Wood 
and moisture are evidently essential to such animals. Turning to the 
snails, which probably all come out into the open to feed during the night 
and during moist weather, we note that they do not appear until the 
under-log beetles put in their second appearance. In general the total 
number of species and of individuals increases until the oak-hickory 
stage is reached and falls off again in the beech and maple stage. 

In general we note that as the forest passes from the bare-sand stage 
to the beech-maple stage, there is a great increase in the space to be 
inhabited by animals and the diversity of possible habitats, at least up 
to the oak-hickory stage. 

I. CAUSES OF SUCCESSION 

The causes of succession in forests are chiefly changes in physical 
condition with increase in denseness of vegetation, such as the increase 



248 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



of moisture of the atmosphere, decreased Ught, decreased temperature 
maximum in summer. The poisoning of the soil by root excretions 
and the modification of conditions on the ground brought about by a 



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Pine dune .» _ 














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.— •• 


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Oak dune •..-..-...-.. 

Beech-maple forest — — 






































































Mill 


1 































Fig. 251. — Mean daily evaporation rates (c.c. per day) in the ground stratum of 
four of the animal communities (after Fuller). 



given set of trees are believed to prevent the germination of seeds of 
most of such trees, and at the same time to prepare the way for those of 



CAUSES OF SUCCESSION 



249 



differently adapted species. The factors as expressed in terms of the 
evaporating power of the air are shown in Figs. 251, 252, and 253, which 
are graphic representations of the results of a season's study by Fuller 
(131). The graph of the Cottonwood dunes is characterized by great 
fluctuations. 

The graph for the pine dunes is decidedly lower and more regular in its 
contour than that of the association which it succeeds. Its four nearly equal 



10 20 


Cottonwood dune 


^ 


_ 


_ 






_ 








■ 










Pine dune 
Oak dune 

Oak-hickory forest 
Beech -maple forest 




































^^ 


^^ 










_ 


_ 
























































■| 


1^1 






































m 


m 
























_ 


_ 







Fig. 252. — Showing the comparative evaporation rates (c.c. per day) in the ground 
stratum of the different animal communities from May to October (after Fuller). 



10 20 30 


Cottonwood dune 
Pine dune 
Oak dune 
Beech'fflaple forest 






^ 


m 


^ 




m 






m 


m 










m 


^ 


P 










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m 


^ 




m 
































^ 


^ 


gi 




^ 
































m 


_ 


^ 




g 







































































Fig. 253. — Showing the comparative evaporation rates (c.c. per day) in four of the 
animal communities on the basis of the maximum amount per day for any week from 
May to October (after Fuller). 

maxima would indicate that within its limits there was, throughout the sum- 
mer season, a continuous stress rather than a series of violent extremes. On 
the whole it shows a water demand of little more than half of that occurring 
in the cottonwood dunes. Its greatest divergence is plainly due to the ever- 
green character of its vegetation and is seen on its low range in May and the 
first part of June, and again in October when it falls below that of the oak 
dunes and is even less than that of the beech-maple forest. This would give 
good reasons for expecting to find within this association truly mesophytic 
plants [and moist forest annuals]' whose activities are limited to the early 
' The words in brackets are added. 



250 DRV AND MESOPHVTIC FOREST COMMUNITIES 

spring. Evaporation in the various associations varies directly with the order 
of their occurrence in the succession. The differences in the rate of evapora- 
tion in the various plant associations studied are sufficient to indicate that 
the atmospheric conditions are most efficient factors in causing succession 
(FuUer, 131). 

A comparison of Fuller's (131) data with the tables or lists of ani- 
mals shows that the distribution and succession of animals is clearly 
correlated with the evaporating power of the air. Further comparison 
with the description of different forest stages shows that the evaporating 
power of the air may be taken, in this case, as an index of the materials 
for abode, etc. 

2. CHARACTERS OF THE COMMUNITIES 

It is possible to characterize the formations of the forest in physio- 
logical terms, though these cannot be of a very definite kind until the 
mores have been studied in detail, and accurate measurements made. 
Taking them stratum by stratum, we may note the following obvious 
characters: 

a) Pioneer communities. — The communities of the cottonwood, pine, 
and black-oak stages may be designated as pioneer because of the 
presence of bare mineral soil. 

Subterranean and ground strata: (a) The cottonwood community 
is characterized by animals which breed and spend the dark and cloudy 
days chiefly below the surface of the sand. They are very largely 
diurnal and predatory, and are exceedingly swift and wary. The bur- 
rowing spider (Geolycosa pikei) is one of the few nocturnal animals. 

(b) The pine community is characterized by similar mores, but is 
to be distinguished from the preceding by the presence of many animals 
which prefer sand that is less shifting and which is slightly darkened by 
humus (170). Animals requiring "cover," such as the lizard, the blue 
racer, a few ground squirrels, etc., give character because of their absence 
from earlier and later communities. 

(c) The black-oak community represents the climax of diversity 
of the subterranean and ground strata. The bare-sand mores continue 
in the open spaces, which we have designated as transition areas. Leaf- 
cutters are now present, while among the burrowers the root-borers 
(prionids and lucanids) work on the roots of the decaying trees. The 
behavior differences between this and the preceding community are 
differences of detail which, for the making of deductions, would require 
much careful studv. 



CHARACTERS OF COMMUNITIES 251 

Field and shrub strata: The field and shrub strata of the cottonwood, 
pine, and oak communities are less easily characterized. The cotton- 
woods of the beach are far less commonly infested with aphid galls than 
are trees of the same species growing in less exposed situations. Further- 
more we have never found any of the lepidopterous larvae such as 
Basilarchia archippus Cram, near the beach. Animals living exposed 
upon the trees are few in number. The same general conditions obtain 
on and among the pines but spiders are more numerous. On the black 
oak the number of phytophagous animals is increased and the number of 
galls appears to be greater than in the later stages; the inhabitants of 
the herbaceous vegetation are chiefly those found in open situations such 
as prairies and roadsides, where the physical conditions are similar. 
Some animals of the same species which make up the black-oak com- 
munity were taken from a roadside, and after being mixed with the 
inhabitants of the shrubs of the beech forest were placed in a light gra- 
dient. Soon the insects and spiders of the two communities separated 
sharply from each other, the beech-inhabiting species going to the dark- 
est end while the roadside species crowded to the light. 

b) Later communities. — •With the coming-in of red oak, true forest 
with the mineral soil largely covered with humus and leaves is present 
and very different mores obtain. The diurnal diggers are practically 
absent. Snails, beetles, grasshoppers, spiders, and myriopods living 
under bark, decaying wood, and leaves, avoiding strong light and 
requiring moisture, are the chief types. The mores are typically forest 
in character. The differences between these and the later stages are 
those of detail and degree. In general with a lessening in the severity 
of the conditions and an increase in the denseness of vegetation, there is 
a proportional increase in the use of the vegetation as a place of abode. 

In the field and shrub strata, we note that the animals of the cotton- 
wood, pine, and oak stages are characteristic of open dry situations, 
requiring or tolerating strong light, while those animals of the red-oak, 
hickory, and beech stage are negatively phototactic to light of the same 
intensity, as shown by mixing the animals in a gradient. 

The animals of the tree strata frequent a limited number of kinds 
of trees. Tree inhabitants are few and scattered in the cottonwood 
pine, and black-oak stage while animals inclosed in galls or cases are 
common, if not dominant. In the red-oak, hickory, and beech stage 
phytophagous animals are often gregarious and numerous. Groups such 
as Orthoptera, beetles, bees, and wasps are represented more and more 
by species which make use of the vegetation as forest development 
goes on. 



252 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



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ANIMALS OF FOREST SUCCESSION 



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254 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



TABLE XLIX. (Table L precedes Table XLIX) 

Showing Forest Animals in the Early Stages of Forest Development or a 
Clay Bluff of Lake Michigan 
Subterranean and ground strata, i; bare clay, 2; sweet clover, 3; shrubs, golden- 
rod, etc., 4; sapling stage, animals same as in (5) the oak-hickory forest (Station 56). 



Common Name 

Tube- weaver 

Lycosid 

Carolina locust 

Mud-dauber 

Tiger-beetle larvae 

Sowbugs 

Centipede 

Snail 

Snail 

Snail 

Tiger-beetle larvae 

Snail 

Slug 

Yellow-margined millipede. 
Centipede 



Scientific Name 

Agelena naevia Wal 

Pardosa lapidicina Em 

Dissosteira Carolina Linn 

Pelopoeus cementarius Dru 

Cicindela purpurea Hmbalis Klg. . . . 

PorcelUo rathkei Brandt 

Geophilus sp 

Polygyra thyr aides Say 

Pyramidula alternata Say 

Polygyra monodon Rack 

Cicindela sexguttata Fbr 

Polygyra albolabris Say 

Philomycus carolinensis Bosc 

Fontaria corrugate Wood 

Lysiopetalum laclarium Say 



1234 

* * 

ie * 

* * 

F C A 

* >i< * 

it: * * 

if * * 

* * 

* * 

* * 

* * 

* * 



ANIMALS OF FOREST SUCCESSION 



255 



ANIMALS RECORDED IN THE GROUND AND SUBTERRANEAN 
STRATA OF THE STAGES NOTED 

In Tables LI-LV, in the third column B indicates breeding; F, feeding; H, 
hibernating, on the situation indicated in column 4. Figures in column "Litera- 
ture" refer to literature cited in the special Bibliography at the end of the book. 
Statements made on the authority of others are in italics; those starred are by 
A. B. Wolcott. 

TABLE LI 

Pine Stage (Stations 57, 58, 59) 



Common Name 


Scientific Name 






Literature 


Bee (Andrenidae) 


Halictus nelumbonis Rob . . . 

Tachytes texanus Cres 

Plesia interrupta Say 

Anoplius marginatus Say. , . 
Coluber constrictor Lin., Var. 
CUellus 13-lineatus Mitch . . . 
Cardiophorus cardisce Say. . . 
Alaus myops Fabr 


B? 

B 
B 

B? 




181 


Larridae 




173 


Scoliidae 




Ceropalidae 


In sand 

u 
u 

On sand 

Under pine 

bark 


173 

IS7 

21 

156 


Blue racer 


Ground squirrel 

Beetle (Elateridae) . . . . 
Elaterid beetle 



TABLE LII 
Black-Oak Stage (Stations 57, 59, 60, 61) 



Common Name 


Scientific Name 






Literature 


Elateridae 


Lacon rectangularis Say 

Languria trifasciata Say .... 
Hippiscus tuberculatus Beau. 
Coelioxys rufitarsus Smith. . . 

Odynerus anormis Say 

Heterodoh platirhinos Latr . . 


B 
B 
B 
B 

B 


Under Opunlia 

u 

In sand 
Bee nest 


* 


Erolylidae 


* 


Coral-winged locust. . . 

Parasitic bee 

Eutnenidae 


40 


Hog-nosed snake 


In sand 


157 



TABLE LIII 
Black Oak-Red Oak Stage (Station 63) 



Common Name 


Scientific Name 






Literature 


Ant 


Lasius umbratus mixtus 
aphidicola Walsh 

Camponotus ligniperdus 
noveboracensis Fitch 

Pterostichus sayi Brulle 

Uloma impressa Mels 


B 

B 
B 
B 


Log 

Log 
Rotten log 
Rotten log 




Ant 


54 


Ground beetles 

Tenebrionidae 


54 
156 
156 



256 DRY AND MESOPHYTIC FOREST COMMUNITIES 

(See explanation above Table LI) 

TABLE LIV 

Red Oak-Hickory Stage (Stations 64, 65, 69) 



Common Name 


Scientific Name 






Literature 


Green tiger-beetle .... 
White-faced hornet . . . 
Andrenidae 


Cicindela sexguUata Fabr . . . 

Vespa macnlata Lin 

Augochlora pur a Say 

Geotrupes splendidus Fabr. . . 
Staphylinus violaceus Grav . . 
Melanotus communis Gyl . . . 

Pallifera dorsalis Bin 

Eupsalis minuta Dru 


B 
H 


In soil 
Rotten wood 


151 

179 


Scarabaeidae 

Staphylinidae 

Elateridae 

Slug 


B 
B 

B 
B 


Rotten log 

u 

u 

Log 
Solid logs 


156 

156 

156 

91 


Brenthid beetle 



TABLE LV 
Beech Stage (Stations 70, 71, 71a, 71b) 



Common Name 


Scientific Name 






Literature 


Froe 


Rana sylvatica Le Conte 

Pachyrhina ferruginea Fabr . . . 

Plelhodon cinereus Gr 

Polygyra inflecta Say 


F 

B 

BF 
BF 
BF 
BF 
BF 
BF 

? 

B 
B 


Ground 

Under leaves 

« 

Leaves and log 

« 

u 
u 
u 
u 

Under bark 
Rotten wood 


139 


Fly larva 


Salamander 

Snail 


91 


Snail 


Polygyra oppressa Say 

Polygyra fraudulenla Pil 

Polygyra palliata Say 

Pyramidula solitaria Say 

Pyramidula perspecliva Say . . . 
Xylopinus saperdioides Oliv . . . 
Aphaenogasler tennesseensis 
Mayr 


Snail 


91 


Snail 


Snail 


91 


Snail 


Beetle 


156, 137 


Ant 













ANIMALS OF FOREST SUCCESSION 



257 



TABLE LVI 

Distribution of Animals Recorded from Vegetation in More Than One of 
THE Animal Communities of the Forest Stages Indicated by Numbers 
I, the Cottonwood stage; 1-2, mixed cotton wood and pine stage; 2, pine stage; 
2-3, mixed pine and oak stage and open places in the oak forest; 3, black-oak stage, 
in its later phases white oaks occur; 4, black oak-red oak stage; 5, stages containing 
hickory but not beech and maple; 6, beech and maple stage. 



Common Name 

(a) Spider (Thomisidae) 

(b) Butterfly 

(c) Spider (Epeiridae) . . 

(d) Dusky plant-bug . . . 

(e) Phasmtdae 

(/) Spider (Thomisidae) 
(g) Spider (Dictynidae) . 
(h) Spider (Epeiridae) . . 
(i) Spider {Theridiidae) 
0) Bug 

(Ji) Stinkbug 

(/) Stinkbug 

(w)Fly 



Scientific Name 

Phllodromus alaskensis Key 
Anthocharis genutia Fabr. . 
Epeira domicilorum Hentz. . 

Lygus pratensis Lin 

Diapheromera femorata Say 
Misumessus asperatus Htz . 
Dictyna foliacea Hentz .... 

Epeira gigas Leach 

Theridium frondeum Hentz. 
Acanthocephala tertninalis 

Dall 

Nezara hilaris Say 

Podisus maculiventris Say. . 
Sapromyza philadelphica 

Mac 



I 


1-2 


3 


2-3 


3 


4 


s 


* 




* 
* 


* 










* 


? 

Hi 


? 


? 


* 


* 
* 




* 






* 
* 


* 
* 

F 
F 


* 

* 

C 

* 

* 
* 
* 

* 



The letters below at the left refer to the species opposite which they stand in 
Table LVI and the numbers refer to the forest stages as at the heads of the columns 
of Tables L and LVI. The capitals have the same meaning as in the preceding tables. 

a — from cottonwoods and juniper (i, 1-2, 3) (138, 172). 

b — from Arabis lyrata (175). 

c — from pine and herbaceous vegetation (B) (4) (172). 

d — herbs (174). 

e — from the trunks of various trees. 

/ — Monarda (2-3), and black oak (3), maple (5) (138, 172). 

g — 'F Monarda (3) (173). 

h — from undergrowth (4), and beech, (5) (138, 172). 

i — from shrubs (4), and young beech (5) (138, 172). 

_/ — shrubs (4) and maple trunk. 

k — from red-oak trunk (4) and beech trunk (5) {Tilia, Citrus, Gossypium 186). 

/ — ? (4) and beech leaves (5) (predaceous, 185). 

VI — herbs. 



2S8 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



ANIMALS RECORDED FROM THE FIELD, SHRUB, AND TREE 
STRATA OF THE FOREST STAGES NOTED 

In Tables LVII-LXII, in the third column B indicates breeding; F, feeding; 
H, hibernating, on the situation indicated in column 4. 

TABLE LVII 

Cottonwood Stage (Stations 57, 58, 59) 



Common Name 


Scientific Name 






Literature 


Chrysomelid beetle . . 
Long-homed borer. . . 
Gall aphid 


Disonycha quinquevittata Say. 

Plectrodera scalator Fab 

Pemphigus populicaulis Fitch. 
Pemphigus vagabuttdus Walsh. 


BF 
BF 
BF 
BF 


Willow 

Cottonwood 
« 

u 


156 
156 
188 


Gall aphid 


188 









TABLE LVIII 
Pine Stage (Stations 57, 


58, 59) 






Common Name 


Scientific Name 






Literature 


Leaf-beetle 


Nodonota tristis Oliv 

Bassareus lativittis Germ .... 
Xysticus formosus Banks .... 
Dendryphantes octavtis Hentz . 

Theridium spirale Em 

Ips grandicoUis Eich 

Evetria comstockiana Fern. ?. . 


F 
F 

BF 
BF 


Herbs 
u 

Juniper 

u 

u 

Pine 

« 


156, 137 






Spider (Thomisidae). . 
Spider {AUidae) 

Spider {Theridiidae). . 

Engraver beetle 

Pitch -moth 


137 
187,138 

173 
138, 172 

137 
137 







ANIMALS OF FOREST SUCCESSION 



259 



(See explanation above Table LVII) 

TABLE LIX 

Black-Oak Stage (Stations 57, 59, 60, 61) 



Common Name 



Scientific Name 



Literature 



Syrphus fly 

Andrenid 

Spider (Thomisidae). . 
Spider (Epeiridae) . . . 

Sprinkled locust 

Grasshopper 

Tree-cricket 

Texas grasshopper . . . 
Conehead grasshop- 
per 

Meadow grasshopper 

Stinkbug 

Flower-bug 

Fork-tailed larvae . . . 

Fulgorid 

Flatbug 

Colydiid beetle 

Prominent larva 

Prominent larva 

Tree-hopper 

Coreidae 

Jassid 

Jassid 



Milesia virginiensis Dru 

Agapostemon splendens Lepel. 
Philodromus pernix Black. . . . 

Argiope trifasciata Forsk 

ChloealHs conspersa Har 

Schistocerca rubiginosa Har . . 
Oecanlhus fasciatus Fitch .... 
Scudderia texensis Scud 

Conocephalns ensiger Har. . . . 
Xiphidium slriclum Scud .... 
Euschistus variolarius Pal. . . . 

TripMeps insidiosus Say 

Cerura sp 

Otiocerus degeeri Kirby 

Neuroctenus simplex Uhl 

Diloma qiiadrigiiUata Say .... 
Heterocampa guUivilta Harr. . . 

Nadala gibbosa S. and A 

Telemona querci Fitch (monti- 

cola) 

Chariesterus antennalor Fabr. . 
Typhlocyba querci var. bifas- 

ciata G. and B 

Phhpsius irroratus Say 



F 

F 

F 

F 

F 

F 

BF 
BF 

BF 
BF 
BF 

F 

BF 
BF 
BF 

F 

BF 
BF 

BF 
BF 

BF 
BF 



Herbs 

Primrose 

Herbs 



Cherry 
Oak 



177 
137 
137 
40 
40 
40 
40 

.40 
40 

174 
i8s 
186 
i8s 
185 
137 
137 
138 

i8s 
I8S 

i8s 
i8s 



26o 



DRY AND MESOPHYTIC FOREST COMMUNITIES 



(See explanation above Table LVII) 

TABLE LX 

Black Oak-Red Oak Stage (Station 63) 



Common Name 


Scientific Name 






Literature 


Jumping spider 

Spider 


Maevia niger Htz 


F 
B 

F 
F 


Herbs 

u 

White oak 

Tree trunks 

Cherry 


138 


Gayenna celer Htz 


White-oak gall 

Predaceous leaf-bug. . 
Scallop-moth (larvae) 


Andricus seminator Harr 

Hyaliodes vitripennis Say .... 
Hydria undulata Lin 


188 



TABLE LXI 

Red Oak-Hickory Stage (Stations 64, 65, 59) 



Common Name 



Scientific Name 



Literature 



Rove-beetle 

Spider (Clubionidae) 

Locustidae 

Spider (Epeiridae) . . 
Spider (Epeiridae) . . 
Spider (Epeiridae) . . 

Jassid 

Beetle 

Bug (Nabidae) 

Spider (Linyphiidae) 

Cicada 

Leaf -beetle 

Stinkbug 

Arctidae 

Oakworm 

Tree-cricket 

Katydid 

Leaf-beetle 

Prominent larva. . . . 
Prominent larva. . . . 
Aphid 



Tachinus pallipes Grav 

Anyphaena cons per sa Key. . . 
Atlanticus pachymerus Burm. 

Acrosoma gracilis Wal 

Acrosoma spinea Hentz 

Mangora maculata Key 

Scaphoideus auronitens Prov . 

Odontota nervosa Panz 

Reduviolus annulatus Reut. . . 
Linyphia phrygiana Koch. . . . 

Cicada linnei S. and G 

Calligrapha scalaris Lee 

Euschistus tristigmus Say . . . . 

Halisidota sp 

Anisota senatoriaSra.axiAKhh. 
Oecanlhus angustipennis Fitch. 
Cyrtophyllus perspicillatus L. . 

Xanthoma lo-notata Say 

Symmerista albifrons S. and A. 
Datana angusii G. and R . . . . 
Phylloxera caryae-caulis Fitch. 



BF 
F 
B 
F 
F 



B 

F 

BF 
BF 
BF 
BF 
BF 

B 

F 

B 

B 

B 



Mushrooms 
Herbs 
Grass 
Shrubs 



Young maple 

« 

u 

White oak 

« 

Red oak 



Maple 
Hickory 



177 

138 
40 
138 
138 
138 
177 



138 
177 

137 

137 
40 



137 
137 
58, 137 



ANIMALS OF FOREST SUCCESSION 



261 



(See explanation above Table LVII) 
TABLE LXII 

Beech Stage (Stations 70, 71, 71a, 716) 



Common Name 


Scientific Name 






Literature 


Beetle 


Boletobius cinctus Grav 

Boletotherus bifurcus Fabr. . . 




Mushrooms 
Shelf fungus 


177 


Fungus-beetle 


177,137 


Cercopidae (bug) .... 


Clasloptera obtusa Say 


F 


Hickory, maple, 
hazel 


i8S 


Leaf- hopper 


Gypona octolineala Say 


F 


Hickory, maple, 
beech 


137 


Leaf-hopper 


Jassus olitarius Say 


F 


Maple 


137 


Ichneumonidae 


Thalessa atrata Fabr 


B 


Larvae 


137 


Lacewing 


Chrysopa rufialbrii Burm . . . 


B 


Maple 




Lacebug 


Gargaphia tiliae Walsh 


B 


Beech 


137 


Ichneumonidae 


Tragus vulpinus Cb 


B 


Larvae 


177 


Pentatomidae 


Banasa calva Say 


F 


Beech 




Lampyrid beetle 


Podabrus basilaris Say 




Maple 


137 


Lvcosidae 


Wala mitrata Hentz 

Nolionella inter pres Cam. . . . 




« 


138 


Theridiidae 


138 


Harvestman 


Oligolophus pictus Wood. . . . 




Maple trunk 


184 


Syrphus fly 


Spilomyia longicornis Loew. . 













CHAPTER XIII 
ANIMAL COMMUNITIES OF THICKETS AND FOREST MARGINS 

I, Introduction 

The forest margin or forest edge is a familiar natural situation. 
About Chicago there are groves of trees which are probably exactly as 
they were before settlement. The forest ends; the prairie begins. The 
line between the two is markedly a narrow border of shrubs and rank 
weeds, usually only a few feet wide. In other places the forest ends at 
a marsh side, lake side, or stream side, but almost always with the 
thicket of shrubs and rank weeds. A remarkably large number of 
animals belong to this forest margin. Some of these have been discussed 
in connection with the margins of bodies of water (chap, x), and the 
marsh forest (chap. x). The borders between forest and prairie 
remain to be discussed. These will be roughly separated into high and 
low forest margin, depending upon height above ground-water level. 
The relations of these formations to the other forest margins will be 
indicated in the tables. 

11. Low Forest Margin Sub-Formations 

(Stations 45, 49; Table LXIII) (Fig. 254) 

Low forest margin is usually the border between swamp forest and 

low prairie. There was originally much of this in the Lake Chicago 

plain. One point of special study is the border of the Wolf Lake marsh 

forest (see p. 189). 

I. subterranean-ground stratum 
The ground is inhabited by earthworms and cicada nymphs, etc. 

No burrowing mammals have been recorded, but it is probable that 

the skunk sometimes breeds in this stratum. 

The cricket (Nemobius maculatus) occurs under fallen leaves, sticks, 

etc., with an occasional snail {Polygyra monodon). The lubberly locust 

often deposits its eggs in the ground (40). Sowbugs and forest-floor 

forms make up most of the remaining species. 

The northern yellowthroat, the song sparrow, and the common 

shrew sometimes nest on the ground. The skunk is sometimes a feeding 

resident. 

262 



MOIST FOREST MARGIN 



263 



2. FIELD AND SHRUB STRATA 

Here two zones may be recognized. While there is no reason for 
separating them in the ground stratum, a rough separation is here 
possible, 

a) Rank weeds, willow, dogwood, grape, etc. 

h) Prickly ash thicket with grape and young elms. 

Outside the first is a girdle of low prairie from which low prairie plants 
and some low prairie animals occasionally invade the forest margin. 

a) Girdle of rank weeds, dogwood, willow, etc. — In open, grassy places 
the garden spiders {Argiope aurantia and trifasciata) (Fig. 255) fasten 




Fig. 254. — Low forest margin at Wolf Lake. Ind. In front of a, low prairie 
area; opposite b, belt of rank weeds: opposite c, low shrubs; opposite (i, high shrubs; 
opposite e, trees. 

their webs to any firm support, such as a young shrub. Various grass- 
hoppers occur in open situations {Xiphidium fasciatum and hrevipenne 
belong more properly to low prairie) (Fig. 256). The long-bodied spider 
{Tetragnatha laboriosa) (138) is a common resident. On the grasses 
beneath the shrubs the black-sided grasshopper {Xiphidium nigropleura) 
is abundant. The snail (Fig. 257) (Succinea ovalis) is sometimes 
common. 

Of the bugs which frequent the blossoms of the coarse weeds are the 
long-legged bug (Neides muticus), the buffalo tree-hopper (Fig. 259), and 
the candlehead {Scolops sulcipes) (Fig. 258). These two and especially 
the latter, with its curiously prolonged prothorax, are the most char- 
acteristic. The common plant-bug (Lygus pralensis) (Fig. 261) and an 



264 



THICKET COMMUNITIES 



occasional dusky leaf-bug (Adelphochoris rapidus) (Fig. 262) are also 
found. The large stinkbugs {Euschislus tristigmus and fissilis Uhl.) are 
common. They may be predatory in the adult stage. The predatory 
ambush-bug {Phymata erosa fasciata) lies in wait for its prey in the 



1 ■■• 1 


^^ , ^W:■^- 


; i 

I, 




■ ! 
1 



Fig. 255. — The garden spider (Argiope aurantia) on its web; about one-half 
natural size. 




Fig. 256. — The slender meadow grasshopper (X^^Ai(f/Mw/aiCia;«iw) (after Lugger). 

blossoms. A crab spider {Mesumena vatia) and a jumping spider 
(Fhidippus audax) are common in the blossoms (40, p. 182.) Various 
lepidopterous larvae feed upon the rank weeds also. 

On weeds and blossoms grasshoppers are numerous; we find the Ne- 
braska conehead (Conocephalus nebrascensis) (see Fig. 260), the lubberly 



MOIST FOREST MARGIN 



265 




Fig. 257. — The forest-margin snail (Succinea ovalis); twice natural size (after 
Baker). 

Fig. 258. — The candle-headed bug {Scolops sulcipes); 5 times natural size 
(original). 

Fig. 259. — The buffalo tree-hopper {Ceresa bubalus); 5 times natural size (after 
Marlatt, U.S. Dept. Agr.). 

Fig. 260. — ^The large cone-headed grasshopper {Conocephalus robustus) (after 
Beutenmiiller [Am. Mus.] from Blatchley). 



266 



THICKET COMMUNITIES 



locust {Melanoplus diferentialis) , an occasional red-legged locust, and the 
striped shrub cricket, the short-winged brown locust (Stenobothrus cur- 
tipennis), the short-winged meadow grasshopper {Xiphidium brevipenne), 
and the Texas katydid {Scudderia texensis) (40, pp. 330, 390). 

The jug-making wasp {Eumenes fraternus) (40, p. 207) makes its 
jug-like nest on the herbaceous plants. The social wasp (Polistes) is 
a frequent visitor of the flowers, 
and sometimes attaches its comb 
to the willow. The oblong leaf- 
winged katydid (Amblycorypha 
oblongifolia) (Fig. 263) (40, p. 
391) and the fork-tailed katydid 





261 262 

Fig. 261. — The tarnished plant-bug {Lygus pratensis); about one-fourth of an 
inch long (after Forbes). 

Fig. 262. — The dusky leaf-bug (Adelphocoris rapidus); about one-fourth of an 
inch long (after Forbes) . 

{Scudderia fur cata) (Fig. 264) are residents. The latter places its egg 
on leaves of shrubs (40). Willow leaf- feeders are numerous; several 
lepidopterous larvae are common. These include the brilliant larva of 
the smeared dagger-moth (Fig. 265), the cecropia moth, the willow 
sphinx, the viceroy and mourning-cloak butterflies, the maia moth 
(Fig. 266), the fork-tailed caterpillar (137), larva of the maia moth, 
and others. The small fly {Bibio alhipennis) visits the flowers of the 



MOIST FOREST MARGIN 



267 



willow in spring (Fig. 267). Sawfly larvae are common; the large light- 
colored one {Cinibex americana) (179) has habits of special interest. The 
female, which is a wasp-like insect, deposits her eggs on the under sides 

of leaves. Blisters are formed, and a 
young larva lives for a time in each 




263 264 

Fig. 263. — The oblong leaf-winged katydid (Atnblycorypha oblongifolia); (after 
Forbes) natural size. 

Fig. 264. — ^The fork-tailed katydid {Scudderia furcata) (after Lugger from 
Forbes); natural size. 

of these. Later it is to be found living freely on the leaves. It usually 

rests with the posterior segments wrapped around a petiole or twig. 

Pupation takes place in a 

silken case. The spotted 

sawfiy larva {Pteronus 

ventralis Say) (179) is less 

common. 

Beetles are common 
on the willow. The leaves 
are eaten by May-beetles 
(189) and several leaf-feed- 
ers {Calligrapha and Lina 
are common). Several 
borers attack the twigs 
{Saperda concolor) . Galls 
are very numerous. The 
trunks of small willows are 
commonly attacked by the 
larvae of the introduced 
snout-beetle (Cryptorhyn- 
chus lapathi), and the 
goat-moth larva (Prionoxystus robiniae Feck.) , which bores in the heart- 
wood. The sap which exudes attracts many sap-beetles {Nitidulidae). 




Fig. 265. — The adult and larva of the smeared 
dagger-moth (Acronycta oblinita), which feeds upon 
various forest-margin weeds and shrubs; natural 
size (after Riley). 



268 



THICKET COMMUNITIES 



The dogwood is fed upon by a few larvae. The unicorn larva 
(Schizura sp.) is occasionally found; the young of the spittle insect 
{Aphrophora 4-notata) are common. The grape and Virginia creeper are 
attacked by several sphinx larvae. The grapevine hog caterpillar 
{Ampelophagus myron Cram.) has been taken from the former. 

Nesting in the shrubs are the goldfinch (more often in trees), the 
indigo bunting, the northern yellowthroat, the brown thrasher, and 

catbird, all of which feed in the 
low prairie. The song sparrow 
nests near the ground. 

h) The belt of prickly ash. — 
This has not been so thoroughly 
studied. The subterranean and 
ground strata are similar to 
those of the forest adjoining (see 



266 





267 



Fig. 266. — ^The larva of the maia moth {Hetnileuca maia) which feeds on the 
willow; natural size (from Lugger after Riley, Div. Ent., U.S. Dept. Agr.). 

Fig. 267. — Bibio albipennis. Early spring on the flowers of the willow. Breeds 
in the ground (from Williston after Washburn). 

p. 269) ; the ground and field strata have some of the same residents. 
The adult Cresphontes butterfly (Papilio cresphontes) is common about 
the Wolf Lake forest edge and Hancock (40) has recorded the larva on 
prickly ash, one of its regular food plants. He also records the true tree- 
cricket {Apithes agitator Uhl.) as inhabiting prickly ash thickets. 



III. High Forest Margin Sub-Formations 

(Station 48; Table LXIV) 

This surrounds the oak-hickory, black-oak, and beech forests on high 

ground. The witchhazel, hawthorn, sumac, and grape are the dominant 

shrubs; goldenrod, asters, and sunflowers are the chief herbaceous plants. 



DRY FOREST MARGIN 269 

I. SUBTERRANEAN-GROUND STRATUM 

Certain earthworms, cicada nymphs, and root-eating grubs belong 
here. This is the regular breeding-place of the skunk (Mephitis meso- 
tnelas avia Bang). According to Seton (143) they go in droves of six or 
eight, and as many as fifteen sometimes occur in a winter den. Accord- 
ing to Seton its food consists of various insects, grasshoppers, crickets, 
meadow mice, snakes, and crayfishes. The short-tailed shrew in primeval 
conditions breeds chiefly in such tangles of bushes. It digs in moss 
and fallen leaves and loamy soil, and follows mouse galleries. According 
to Wood (21) it eats many mice. Seton (143) states it feeds on isopods, 
earthworms, etc. Its enemies are hawks, lynxes, and weasels. 

Franklin's ground squirrel (Citellus franklini Sab.) burrows into the 
ground deeper than the ground squirrel of the prairies, but is otherwise 
similar in habits. It is gregarious and stores grain for winter. The 
chipmunk {Tamias striatus griseus Mear.) is a typical forest margin 
animal. It nests in the ground, as a rule in burrows about 6 to 10 ft. 
long and running diagonally down to a depth of 2 to 3 ft. (21). It stores 
nuts for winter. The jumping mouse (Zapus htidsonius Zim.) is one of 
the most characteristic residents; it moves by great leaps and steers its 
flight with its tail. The woodchuck should probably be counted here, 
though it belongs deeper in the forest than any of the others. The weasel 
is common in this situation, though it is perhaps more abundant along 
streams (Wood). 

The ground stratum supports many of the small animals of the 
adjoining forest, such as centipedes, camel crickets, etc. The cottontail 
is one of the chief residents, as it usually breeds in such situations. The 
common shrew {Sorex personatus St. Hil.) (21) breeds on the ground, in 
stumps, etc. All of the mammals recorded in the preceding stratum 
feed here when suitable food is present. A considerable number of 
mammals commonly regarded as belonging to the forest are said to prefer 
thickets. The Virginia deer is one of these. It is probable that the elk 
was somewhat similar in habits. 

The bobwhite and mourning dove (occasionally) breed in these situ- 
ations, the former often falling a victim to the weasel (Wood). The 
high forest margin was probably a favorite location for the huts of the 
aborigines. Some of the early travelers record huts around the edges of 
the prairies. Such locations would supply shelter and firewood, etc., as 
well as sunshine. 

2. FIELD AND SHRUB STRATA 

Here the ground-cherry, milkweed, and thistle have a characteristic 
fauna. On the milkweed are the larvae of the monarch butterfly, the 



270 



THICKET COMMUNITIES 



milkweed beetle {Tetraopes tetraophlhaltnus Forst.) (40, p. 136), and the 
leaf-beetle {Doryphora clivicollis) ; the latter is very characteristic. The 
milkweed flowers attract hosts of flies which are preyed upon by vari- 
ous digger-wasps; bees are numerous, gathering honey. The ground- 




268 269 

Fig. 268. — The four-lined leaf-bug {Poecilocapsus lineatus); a, adult; b, c, imma- 
ture forms; 5I times natural size (from Lugger). 

Fig. 269. — A long-legged fly {Psilopodinus sipho Say) ; enlarged (from Williston 
after Lugger) . 





270 

Fig. 270. — A large robber-fly {Dasyllis sp.); natural size (from Williston after 
Kellogg). 

Fig. 271. — ^A syrphus fly {Eristalis tenax); i| times natural size (from Williston 
after Kellogg). 

cherry is the food plant of the "Spanish fly" {Epicuata) and the 
Colorado potato-beetle. On the thistle we find the larvae of the cos- 
mopolitan and painted-lady butterflies (Pyrameis huntera Fab. and 
cardui Lin.). One of the most characteristic bugs is the 4-lined 



DRY FOREST MARGIN 



271 




272 




273 



Fig. 272. — ^A leptid fly {Coenomyia ferruginea); enlarged (after Williston). 

Fig. 273. — A large syrphus fly (Milesia mrginicnsis); enlarged (after Williston). 



272 



THICKET COMMUNITIES 



leaf -bug {Poecilocapsus lineatus) (Fig. 268). The long-legged fly 
(Fig. 269), the large robber-fly (Fig. 270), the common syrphus fly 
{Eristalis tenax) (Fig. 271), a leptid fly (Fig. 272), and Milesia virginien- 
sis (Fig. 273) visit the flowers in numbers. The garden spider occurs; 
also high in the shrubs is the brilliant Epeira gigas found also in the 
forest openings. The goldenrod gall-forming fly {Straussia longipennis) 
(Fig. 274) with its beautifully marked wings is common. Professor 




275 



276 



Fig. 274. — ^The goldenrod gall-fly {Straussi longipennis); much enlarged (from 
Williston after Kellogg) . 

Fig. 275. — One of the crane-flies {Helobia hybrida) ; enlarged (from Williston after 
Lugger). 

Fig. 276. — ^The tree-cricket {Oecanthus fasciatus); twice natural size (after 
Lugger). 



Williston states that the crane-fly (Helobria hybrida) (190) (Fig. 275) 
occurs. Several leaf -bugs occur; the dusky leaf-bug is common. 

Several species of Orthoptera are characteristic. Of the tree-crickets 
several occur among which are Oecanthus nivens DeG. and angustipennis 
Fitch and fasciatus (Fig. 276). Two or three katydids occur; the 
round- winged {Amblycorypha rotundifolia Scud.) is most characteristic. 



DRY FOREST MARGIN 



273 



The grape often grows in these situations, and is especially subject to 
attack by the Phylloxera (Fig. 277) and the grapevine June beetle, the 
larvae of the 8-spotted forester (Alypia odomacidata Fabr.), and the 
grapevine epimens (Psychomorpha epimensis Drury) (163). All of these 
spend a part of their lives in the ground. The Phylloxera (Fig. 277) 
winters on the roots of the grape. The grape-beetle larva bores in wood. 
The pupae of the two moths bore into rotten wood or the ground for 
pupation and also to spend the winter. This may be an important cause 
for their presence in the forest margin. Brownie-bugs are common 
(Fig. 278). 



-^=^^^^-^ .=^5XC 




Fig. 277. — The grapevine Phylloxera {Phylloxera vastalrix Planch.): a, leaf galls; 
b, section of gall with mother louse at center with young clustered about; c, egg; 
d, nymph; e, adult female; /, same from side," a, natural size, others much enlarged 
(after Marlatt, Div. Ent.. U.S. Dept. Agr.). 



One of the most interesting forms found here is Mantispa brunnea 
(Fig. 279). This is a neuropterous insect with forelegs adapted for 
seizing prey. Its larva is a parasite in the egg-cases of spiders. The 
adult appears in July. In the autumn, after the leaves have fallen, one 
sees many nests of spiders on the high forest margin shrubs, so the young 
parasites have a good chance to secure their best food conditions here. 

Hawthorns often occur, and on the trunks we find woolly plant-lice 
(Schizoneura) in great white clusters (150). The hawthorn supports 
many of the pests of the apple. 



274 



THICKET COMMUNITIES 



The birds of the high forest margin are numerous (191). The gold- 
finch builds a nest of thistledown, grasses, etc., on shrubs or low trees. 
The chipping-sparrow builds its nest of rootlets and lines it with horse- 
hair. The Baltimore and orchard orioles build elaborate nests on the 
shrubs and feed in the open. The field sparrow sometimes builds 
on the rank weeds, in other cases on shrubs near the ground. The 
mourning dove, the indigo bunting, and the yellow warbler nest on 
shrubs; the latter often builds near water. The redstart builds in the 
forks of bushes and trees. The loggerhead shrike is common. The 
sparrow-hawk nests in deserted woodpecker holes near the edge of the 
woods and feeds in the meadow or prairie. The flicker is similar in 





278 

Fig. 278. — A brownie-bug (Enchenopa 
binotata Say); enlarged (after Lintner). 

Fig. 279. — One of the Mantis-like 
neuroptera (Mantis pa brunnea); enlarged. 

habits, but uses holes of its own making. The bronzed grackle and 
sharp-shinned hawk nest in trees near the forest edge and feed in the 
prairie. The cowbird, which lays its eggs in the nests of other birds, 
often chooses those nests of the high forest margin. 



IV. General Discussion 

The forest margin, as we have seen, possesses in addition to the char- 
acteristic species a considerable number of species which frequent the 
prairie or forest; our list includes the breeding species. The classifica- 
tion below shows the various types of habit in birds and mammals. 

Forest Margin Birds and Mammals 
(Compiled from literature cited) 
H indicates high forest margin; L, low forest margin. 
A. Breeding in the ground under the shrubs; feeding in the meadows or 
prairies and woods. 

1. Mammals: Skunk (H), Chipmunk (H), Franklin ground squirrel (H), 
Jumping mouse (H). Feed chiefly in woods. 

2. Birds: No birds have this habit. 



THICKET ANIMALS 275 

B. Breeding on the ground among the shrubs and feeding in the open meadows 
or prairies. 

1. Mammals: Common shrew {Sorex personatus) (L), the cottontail (H). 

2. Birds: Bobwhite (H), mourning dove (H) sometimes, northern yellow- 
throat (Z.) sometimes, song sparrow (L) sometimes. 

C. Breeding on the shrubs and feeding in the forest edge and sometimes in 
the open meadows or prairies. 

1. Mammals: None. 

2. Birds: (o) Low forest margin: song sparrow, goldfinch, indigo bunting, 
northern yellowthroat, brown thrasher, and catbird. 

(b) High forest margin: goldfinch, lark sparrow, chipping-sparrow, 
field sparrow, indigo bunting, yellow warbler, redstart, loggerhead 
shrike, mourning dove, catbird, cowbird, Baltimore oriole, bronzed 
grackle, brown thrasher. 

D. Breeding in the trees of the forest and feeding in the prairies. 

1. Mammals: raccoon. 

2. Birds: Sparrow-hawk, sharp-shinned hawk, and several other hawks, 
flicker, bronzed grackle. 

The list shows animals which breed in the margin of woods and often 
feed not only there but in the prairies. Similar relations were noted by 
Bates in the savannas along the middle Amazons. The advantage of the 
forest margin lies in the facts of: (i) shade for the nocturnal and crepus- 
cular forms; (2) abundant space in the thickets for nests; (3) large stiff 
plants which accommodate the large animals: (a) places for the spiders to 
stretch their nets; (b) plants large enough for the roosting- and nesting- 
places of birds and larger insects; (4) protection from wind and from 
winter freezing afforded by the forest. From the standpoint of food 
relations many forest margin animals must be counted in with the 
prairie forms. 

One of the most striking facts concerning the forest margin animals 
is (a) their wide distribution and (b) their survival under agricultural 
conditions. Many animals of importance as crop pests belong to forest 
edges rather than to the forest proper. They take possession of the road- 
sides when the country is cleared. Their distribution is a function of 
the forest margin type of habitat. While it is a characteristic feature 
of the forest border area, it is also to be found extending along the 
wooded streams into the great plains and toward the east through the 
forest area, as the shrubby bluff, the creek and river margin, the fired 
area, and the marsh margin. While local and always leading a precari- 
ous existence in unstable situations, this type of community, probably 



276 



THICKET COMMUNITIES 



by virtue of its adaptation to such conditions, has given us a very large 
number of animals of very considerable economic importance. Tables 
LXIII and LXIV indicate the forms which we have found common to 
the forest margins and other situations. 



TABLE LXIII 

Animals Recorded for a Moist Low-Ground Forest Margin or Thicket Near 
Wolf Lake (Station 45) 

The names that are starred represent animals that have been recorded from the 
shrubs and weeds along the margins of bogs, lakes, ponds, and streams, June 15 to 
August 30. 



Common Name 



Scientific Name 



Orb-weaving spider 

Jumping spider 

*Garden spider 

*Long-bo(iied spider 

*Orb- weaving spider 

*Orb-weaving spider 

Black-sided locust 

Tree-cricket 

Fork- tailed katydid 

Nebraska conehead 

*Robust lubberly locust . . 
*Red-legged grasshopper . , 

*Grasshopper 

*Oblong-winged katydid . . 

Long-homed grasshopper 

Coreid 

Candlehead 

Stinkbug 

*Four-lined leaf -bug 

Coreid 

Solitary wasp 

*Buffalo tree-hopper 

Long-legged bug 

*Ambush-bug 

*Plant-bug 

*Tamished plant-bug. . . . 

Flower ground beetle . . . 
* Willow-beetle 

Willow-borer 

Elm-borer 

Introduced beetle 

*Goldenrod beetle 

Fork-tailed larva 

*Wasp 

*Jug-making wasp 

*Sawfly 

Swallowtail 

*Maia larva 



Shiga variabilis Em. 

Attus palustris Peck. 

Argiope aurantia Lucas 

Tetragnatha laboriosa Htz. 

Epeira trivittata Key 

Epeira trifolium Htz. (rare) 

Xipkidium nigropleura Bruner 

Oecantkus fasciatus Fitch 

Scudderia furcata Bruner 

Conocephalus nebrascensis Bruner 

Melanoplus differentialis Thos. 

Melanoplus femur-rubrum DeG. 

Melanoplus bivittahis Say 

Amblycorypha oblongifolia DeG. 

Orchelimum indianense Blatch. 

Protenor belfragei Hagl. 

Scolops sulcipes Say 

Euschislus fissilis Uhl. 

Poecilocapsus lineatus Fab. 

Corynocoris distinctus Dal. 

Odynerus tigris Sauss 

Ceresa bubalus Fab. 

Neides mutiais Say 

Phymata erosa fasciala Gray 

Adelpkocoris rapidus Say 

Lygus pratensis Linn. 

Callida punctata Lee. 

Lina scripta Fab. 

Saperda concolor Lee. 

Saperda lateralis Fab. 

Cryptorhynchus lapathi Linn. 

Trirhabda tormentosa canadensis Kirby 

C crura sp. 

Polistes variatus Cress. 

Eutnenes fraternus Say 

Cimbex americana Leach. 

Papilio cresphontes Cram. 

Hemileuca maia Dru. 



THICKET ANIMALS 



277 



TABLE LXIV 

AxiMALS Recorded from the Medium Moist or Climatic Forest Edge or 
Thicket at Riverside, III. (Station 48) 
Those starred have been taken from weedy and shrubbv roadsides and identified 
by specialists. According to the author's field identification nearly all should be 
starred. 



Common Name 


Scientific Name 


Month 


Crab-spider 


Runcinia aleatoria Htz 


69 

69 
6 


Jumping spider 


Maevia niger Htz 


Spider 


Pisaurina undata Htz 


Spider {Dictynidae) 


Dictyna foliacea Htz 




*Orb- weaving spider 


Epeira trifolium Htz 


69 
6 


Spider 


Atypus milberti Walck 


Spider 


Clubiona obesa Htz 


6 


Texas grasshopper 


Scudderia texensis S. and P 


g 


Spittle insect 


Cldslopterd pToteus Fitch 


6 


Leaf-hopper 


Diedrocephala coccinea Forst 

Poecilocapsus lineatus Fab 


6 


Four-lined leaf -bug 


6 


Leaf -bug 


Stiphrosoma stygica Say 


6 


Leaf -bug 


Ilnacora stulii Reut 


6 


Stinkbug 


Podisus maculiventris Say 


6 


Long-homed beetle 


Oberea tripunctata Sw 


6 7 

7 
7 
7 
7 
7 
8 


Long-homed beetle 


Dectes spinosus Say 


Tortoise beetle 


Coptocycla bicolor Fab 


Tortoise beetle 


Copiocycla signifera Herbst 


*01d-f ashioned potato-beetle. . . . 


Epicauta tnarginata Fab 


*Goldenrod blister beetle 


Epicauta pennsylvanica DeG 


Dock curculio 


Lixus macer Lee 


Leaf-beetle 


Chelymotpha argus Herbst 




Beetle (Erotylidae) 


Languria angustata var. trifasciata Say. . 
A crapteryx gracilis Newm 


6 8 


Beetle {Erotylidae) 


6 


♦Beetle 


Odontota nervosa Panz 


6 




Pelidnota punctata Linn 


8 


*Milkweed leaf-beetle 


Doryphora clivicollis Kirby 


7 8 


Ground beetle 


Lebia atriventris Say 


7 8 


Oak -pruning twig-borer 


Elaphidion villosum Fab 


Flower beetle (Carabidae) 


Callida punctata Lee 




Lantern-fly 


Megamelus tnarginatus Van D 


6 


Wasp 


Crabro interruptulus D.T 


5 
S 
4 5 
5 
5 
S 


Bee {Haliclidae) 


Chloralictus cressoni Rob 




Helobia hybrida Meig 


Crane-fly 


Pachyrhina ferruginea Fab 


Fly 


Coenomyia ferruginea Scop 


Goldenrod gall fly 


Straussia longipennis Wied 







CHAPTER XIV 

PRAIRIE ANIMAL COMMUNITIES 

I. Introduction 

We have noted that a part of the region about Chicago is to be 
classed as savanna and that the savanna is made up of trees in groves 
and along the streams, and of forest margin and prairie. Prairie may 
roughly be separated into high and low. The low prairie commonly 
exists in depressions in the moraine, lower places in the plain of old 
Lake Chicago. They are usually covered with water in the spring. 
The high prairie is above water and is dominated by different plants. 
As the depressions are filled or become better drained, high prairie 
plants capture the habitat. 

II. Prairie Formations 

We have noted that the low prairie is covered by water in spring 
(Figs. 280, 281). As the water dries up, which usually occurs by the 
middle of May, the prairie plants begin to grow and the prairie animals 
make their appearance. This change does not take place abruptly, 
but gradually. There is a succession of adult-stage animals through 
the summer. This is what is known as seasonal succession. 

I. seasonal succession 
When the snow melts in March and the frost goes out of the ground, 
the salamander {Ambly stoma tigrinum) comes out of the ground and 
soon deposits masses of eggs in the water. The young of Eubranchipus, 
Cyclops, and rotifers appear after a few days and often reach adult size 
by April i. On April 6, 1908, Mr. Dimmit found adult Eubranchipus, 
Cyclops, and rotifers in the pond south of Jackson Park. The sala- 
manders had disappeared. On April 12 three species of flatworms 
{Vortex viridis, Planaria velata Stringer, and Dendrocoelum) had appeared, 
and the first frogs were noted. On April 14 he found frogs' eggs and 
the red crustacean (Diaptomus). Eubranchipus was at its maximum 
abundance. On April 19 he found Daphnidae, rhabdocoel worms, and 
tadpoles. On May 3 but few Eubranchipus were found. Diaptomus was 
plentiful, perhaps at its maximum abundance. Daphnidae was more 
abundant than before. Planaria were near their maximum. On May 10 

278 



LOW PRAIRIE 



279 



Eubranchipus serralus had disappeared and Diaptomus was not common. 
Our next record is one month later, when the grasshoppers and other 
prairie or land species had begun to appear. This succession is of 
annual occurrence. The temporary pond community is seasonally 
succeeded by the low prairie community. Flies which breed in water, 




Fig. 280. — A prairie pond, still permanent. 
Fig. 281. — ^A temporary prairie pond in spring, 
that a crop was harvested the preceding season. 



The short dead grass indicates 



such as Scoliocentra (Fig. 282) and Tetanocera (Fig. 283), are common 
(also Figs. 284, 285, 286). 



LOW PRAIRIE ASSOCIATION 



a) The subterranean- ground stratum (Stations 42, 43, 44, 45; Table 
LXV). — Earthworms are abundant. Several of the grasshoppers de- 
posit their eggs in the ground. The larvae of the click-beetle {Melanotus 



28o 



PRAIRIE COMMUNITIES 




282 




283 

Fig. 282. — ^A low prairie fly {Scoliocentra helvola Loew); enlarged. 
Fig. 283. — A low prairie fly {Tetanocera umhrarum)', enlarged. 



LOW PRAIRIE 



281 




Some Low Prairie Flies 
Fig. 284. — Pipunculus fuscus (after Lugger from Williston). 
Fig. 285. — Tahamis lineola Fabr. (after Lugger from Williston). 




Fig. 286. — Spilogaster sp, from Williston, who says it inhabits high grass. 



2«2 



PRAIRIE COMMUNITIES 



fissilis), of the strawberry flea-beetle {Typophorus canellus), and the 
com rootworms (Diabrotica) (174), and of many other insects well 
known in economic literature, burrow into the roots of the plants in the 
larval stage. Many of the grass-eating cutworms, caterpillars, and 
sawflies (Fig. 287) pupate beneath the surface of the ground. The 
salamander {Amhly stoma tigrinum) spends ten months of each year buried 
in the mud of such temporary ponds. The Pennsylvania meadow-mouse 
(Microtus pennsylvanicus Or.) has been common in these situations. 




Fig. 287. — Grass sawflies: a, eggs; b, larvae (a and b natural size); c, larva; 
d, cocoon; e, adult male; /, adult female (c to / enlarged as indicated) (after Marlatt, 
Insect Life). 

The star-nosed mole burrows beneath the sod. It is remarkable for its 
curiously fringed nostril. The wetness of the ground excludes other 
burrowing mammals. 

One of the most abundant forms found here is the snail (Succinea 
mara). The ant {Formica subpolita var. neogagates Em.) is also usually 
common. It builds a hill and burrows below the surface of the ground 
also. Several snout-beetles, the adult click-beetles, and the short- 
winged grouse locust {Tettigidea parvipennis and pennata) are common 



LOW PRAIRIE 



283 



on the ground. The 6-spotted spider (Dolomedes sexpunctatus) preys 
upon the other small animals. The common toad and the marsh tree- 
frog {Chorophilus nigritus) are common (139). The latter is particularly 
abundant in the autumn. Its eggs are laid in April in the temporary 
pools. Transformations are complete by the last of May, The prairie 
garter-snake (Thamnophis radix) was formerly common. It is known to 
feed upon the swamp tree-toad. The prairie water-snake {Tropidonotus 
grahamii) was formerly common in and about prairie sloughs (22). 

The bobolink builds a nest here in a bunch of grass; the meadow 
lark and dickcissel build nests of grass and weeds, usually arched over. 
The bisons, residents of the high prairie, were fond of rolling in the low 




Fi<5. 288. — The large green leaf-hopper 
(Draeculacephala mollipes) : a, young; b, one 
half-grown; c, adult; enlarged as indicated 
(after Forbes). 

Fig. 289. — ^The six-spwtted leaf hopper 
(Cicadula sexnotata); enlarged as indicated 
(after Forbes). 




289 



wet places on the prairie and covering themselves completely with mud. 
This must have destroyed numbers of pond animals and badly disturbed 
others. 

h) The field stratum (Stations 42, 43, 44, 45; Table LXVI). — This 
is the chief stratum. While various conditions of the subterranean 
and ground strata, depending upon nearness to ground water, could be 
recognized, our studies have not been sufficiently detailed to warrant 
attempts at separation. A girdle of bulrushes can, however, often be 
distinguished. 

Bulrush girdle: Two of the large green leaf-hoppers (Draecula- 
cephala mollipes [Fig. 288] and Cicadula 6-notata [Fig. 289]) are common. 
The damsel-bug (Reduviolus ferus), which feeds upon leaf-hoppers, is 



284 



PRAIRIE COMMUNITIES 



sometimes taken. The slender meadow grasshopper (Xiphidium fasci- 
taum) is common, but breeds in the sedge zone. A flea-beetle {Monachus 
saponatus), the 12-spotted Diabrotica (DiabroHca 12-punctata) (156), 
and the salt-meadow snout-beetle {Endalus limatulus) (156) are the 
chief beetles. 

The spiders {Epeira trivittata and Tetragnatha laboriosa) are common. 

The flies of this girdle are perhaps the most noteworthy insects Several 

species of brownish or yellowish flies with conspicuously marked wings 

are nearly always common. They are Sciomyzidae (Tetanocera plumosa 

and umbrarum) (Fig. 283). Other characteristic 

^ ^^ flies are Osinidae {Chlorops sulphurea Leow.), 

midges, mosquitoes, DoUchopodidae, Rosophilidae, 

and Anthomyidae. The blue and yellow moth 

(Scepsis fulvicollis) is common. 

Boneset and sedge girdle: The buffalo tree- 
hopper (Ceresa bubalus) (Fig. 259) is found here. 
The dusky (Fig. 261) and tarnished plant-bugs 
(Fig. 262) suck the juices of the mint and other 
plants. The ambush-bug and the damsel-bug 
often lie in wait in the blossoms for prey. 





290 

Fig. 290. — Larva of the salt-marsh caterpillar {Estigmena acraea Dru.) ; natural 
size (after Forbes). 

Fig. 291. — Adult female of the same; natural size (after Forbes). 



Aphids occur and with them are the syrphus flies, lady-beetles, 
and other aphid enemies (164), which are discussed more fully in 
connection with high prairies. The bright green beetle {Chryschus 
auratus) feeds on the small-leafed milkweed. One of the corn "bill- 
bugs" (174) or snout-beetles (Sphenophorus pertinax Oliv.), another 
snout-beetle (Cryptocephcdus venustus), common garden pests, as well as 
the leaf -beetle {Typophorus canellus) are common (174). 

One of the most characteristic groups of the low prairie is that of the 
grass-feeding larvae. The first of these to appear in spring is the grass 



LOW PRAIRIE 



28s 



sawfly (Fig. 287), which is very abundant in early June. Associated 
with this are many caterpillars (174). The greasy cutworm (Agrotis 
ypsilon Rott.) feeds upon the strawberry. The army worm (Lucania 
unipuncta Haw.) feeds upon a variety of plants, and several of its near 
relatives occur. The larvae of the salt-marsh caterpillar {Estigmene 
acraea) (Figs. 290, 291), the yellow bear {Diacrisia virginica Fab.) (Fig. 
292), hedgehog caterpillar (Jsia Isabella S. and A.), and Apantesis 
phalterta Harr. are common. 

Of the Orthoptera, Xiphidium fasciatum and the 2-lined locust (Melano- 
plus bivittatus), the red-legged locust {Melanoplus femur-rubrum) , and 
the short-winged brown locust {Stenobothrus curtipennis) (Fig. 293) 
are most characteristic. 




293 

Fig. 292. — ^The yellow bear: o, larva; 
b, adult {Diacrisia virginica Fabr.) ; nat- 
ural size (after Forbes). 

Fig. 293. — The short-winged brown 
locust (Stenobothrus curtipennis) (after 
Lugger). 



On the flowers are many flower-frequenting flies, viz., Sparnopolius 
flavins Wied., Asilus sp., Syritla pipiens Linn., Coenosia spinosa Walk., 
Paragus angustifrons Loew., Pachryrhina ferruginea, and Hehphilus 
conostoma Will. Preying upon the various insects are the mud-dauber 
wasp {Scelipron cementarius) and the digger-wasp (Ammophila nigricans). 
Parasites, such as Ichneumon zebratus, Paniscus gemminatus, Epeolus 
cressonii, etc., occur upon the plants, and certain of them are often 
found engaged in depositing eggs in or on caterpillars. The onion-fly 
(Tritoxa flexa) (190) is striking because of its black body and black 
wings, obliquely marked with white. 

Spiders, especially crab spiders, are abundant. The white Misumena 
vatia occurs on the milkweed and the flowers of the mint. Epeira 
triviUata and the long-bodied spider (Tetragnatha laboriosa) occur on the 
blossoms and stems of various plants. 



286 PRAIRIE COMMUNITIES 

HIGH PRAIRIE ASSOCIATION 

(Stations 47, 48; Table LXVII) (Fig. 294) 

The type of vegetation which dominates the high prairie is most 
noticeably characterized by the silphiums — the rosin-weed and the com- 
pass plant. The former has broad undivided leaves, the latter divided 
leaves which usually face east and west. This plant formation springs 
up throughout the temperate American forest border area on all well- 
drained ground. It succeeds the low prairie as the depressions occupied 
by the latter are filled or drained. The high prairie then succeeds the 
low prairie just as the bulrushes succeed the pond plants; the sedges, 
the bulrushes; and the boneset association, the sedges. All stages in 
the development of a pond into prairie may be found near Chicago. 
Dr. Cowles is of the opinion that shallow ponds with gently sloping 
sides develop into prairie, while deeper ponds with steep sides develop 
into forest. 

a) Subterranean- ground stratum. — Earthworms abound. The larvae 
of the May-beetles and other Scarabaeidae are abundant, feeding on the 
roots of the prairie plants. The May-beetle is often parasitized by a 
wasp larva {Tiphia vulgaris) (Fig. 297, p. 289) (189). The eggs of the 
2-lined locust {Melanoplus bivittatus) are deposited here in the ground. 

The 13-lined ground squirrel (Citellus ij-lineatus) (21) is a slightly 
gregarious species, strictly diurnal, staying in during dull and cloudy 
days. Its burrows are from 3 to 16 in. below the surface, and often have 
five or six entrances into a larger cavity lined with grass. In a den 
studied by Thompson-Seton the nest was centrally located. Food, 
which includes cabbage butterflies, cutworms, grasshoppers, beetles, 
ants, birds (shore lark and lark bunting), and vegetation, is carried in 
the cheek pouches and stored. The species is non-social, A brood of 
about eight young are produced in April. 

The prairie deer- mouse (Peromyscus bairdii H. and K.) (21) is still 
probably common. According to Thompson-Seton (143) its home range 
is about 100 yds. It is neither social nor gregarious. It is strictly 
nocturnal and active all winter, though some seeds are stored. Its 
food is chiefly seeds. Hawks and owls frequently prey upon it. 

Of the extinct forms several are characteristic. The coyote (Cams 
latrans Say) was formerly common. According to Thompson-Seton 
(143), its home range is ten miles. The den is in a bank or an abandoned 
badger hole. The nest is a cavity 3 ft. in diameter, with an air-shaft. 
It is not so social as the gray wolf. Three to ten young are produced 



HIGH PRAIRIE 



287 




P^ 



O 



288 



PRAIRIE COMMUNITIES 



in April and are fed on disgorged food by the mother. The food con- 
sists of ground squirrels, mice, rabbits, frogs, birds, and grasshoppers. 

The badger (Taxidea taxus Schr.), according to Thompson-Seton, 
digs a U-shaped burrow with two. openings about 6 ft. deep. It is a 
very rapid burrower. It is nocturnal, but basks in the sun at the 
mouth of its burrow and hibernates. Its food consists of mice and 
ground squirrels. 

The pocket gopher {Geomys hur sarins Shaw), according to Thompson- 
Seton, makes a burrow 3 in. wide. It burrows with its feet and when 




Fig. 295. — ^The nest and eggs of the prairie chicken. Photo by T. C. Stephens. 

a pile of dirt has been loosened, turns about and forces it to the exterior 
with its head. The coyote sometimes rears its young in badger holes on 
the prairies. 

On the ground we find ants (Myrmica rubra scabrinodis) , one thou- 
sand of which were found by Judd (191) in the stomach of a single night- 
hawk. Ground beetles are common. Crickets, spiders, and weevils 
all frequent the ground. Most of the field stratum species hibernate 
on the ground under the fallen plants. 

The common toad is rarely wanting near water. The garter-snake 
(Thamnophis radix) has been recorded by Ruthven (156) from such 



HIGH PRAIRIE 



289 



situations in Iowa. The green snake {Leopeltis vernalis) is the most 
characteristic reptile. The prairie rattlesnake or Massasauga {Sis- 
trurus catenatus) was formerly common (22). 

Eight nesting birds, all of which are quite familiar to everyone, occur. 
The bobolink nests in a bunch of grass. It feeds upon flea-beetles, 
weevils, ants, bees, wasps, and grasshoppers of the field stratum. The 
meadow lark feeds on parasitic hymenoptera, including the parasite of the 
May-beetle, ground beetles, crickets, grasshoppers, weevils, spiders, etc. 
The dickcissel is similar in habits. The grasshopper sparrow feeds on 
long-horned grasshoppers, flea-beetles, cutworms, and parasitic hymen- 
optera. The vesper sparrow feeds upon moths, flies, ants, beetles, 
grasshopper eggs, etc., and grain and weed seeds. The nighthawk 
builds no nest, flies at twilight, and feeds chiefly upon ants. The 





297 

Fig. 296 — The adult of the wasp which 
is parasitic on the May-beetle grubs 
(Tiphia vulgaris) (after Forbes). 

Fig. 297. — ^The larva of the same (after 
Forbes). 



prairie chicken is the most characteristic bird. Its nest is a simple 
hollow in the grass (Fig. 295). The prairie horned lark builds a nest 
lined with thistledown and feathers. The lark bunting nests in a tuft 
of grass. 

All of the mammals noted in the subterranean stratum should be 
added here, as nearly all of them feed largely in the ground and field 
strata. 

The field-mouse {Microtus ochrogaster Wagner) (21) is a resident of 
the ground stratum. Its nest is a pile of grass fragments on the ground. 
The species feeds chiefly upon grasses and cultivated plants. The 
bison {Bison bison Linn.) is the most characteristic mammal. Thompson- 
Seton says that the bison population of North America was originally 
75,000,000. This animal generally went in clans or families which are 
said to have had characteristics of their own. An old cow was the 



290 



PRAIRIE COMMUNITIES 



usual leader of the clan. On the great plains these united 
and formed the larger herds of 20,000 to 4,000,000 or more, 
which have been described by travelers. The males aided 
in defending the young. The cowbird is said to have fol- 
lowed the herds constantly. 

h) Field stratum. — The lepidopterous larvae are similar 
to those of the low prairie, but much less numer- 
ous. The hymenoptera are represented by Bom- 
bus separatus, and many of those recorded on the 
low prairie. The adult of the parasite (Tiphia 
vulgaris) of the May-beetle larva 
(Figs. 296-97) occurs commonly. 
Several species of aphids (Figs. 
298-300) occur, especially on the 




milkweeds and thistles. 
These are commonly at- 
tended by ants, which 
stroke them and secure the honey dew from 
the posterior ends of their alimentary canals. 
The aphids reprcduce rapidly, the young being 
born in rapid succession at a very ad- 
vanced state of development. They 
begin sucking the juices of the plant 
at once. Several small parasitic 
hymenoptera (braconids) (Fig. 
299) lay their eggs in the bodies 
of the aphids. These finally kill 
the aphids, whose bodies with 

Fig. 298. — A viviparous grain louse {Macrosiphum granaria Kirby) with her 
newly born young on a barley leaf (after Washburn, Bidl. 108, Minn. Agr. Exp. Sta., 
Fig. 2, p. 262). 



HIGH PRAIRIE 



291 





300 

Fig. 299. — A parasitic wasp depositing 
eggs in the body of a grain louse (after 
Washburn, Bull. 108, Fig. 16, p. 274). 

Fig. 300. — ^A louse killed by a parasite 
(after Washburn, loc. cit., Fig. 12, p. 276). 




Fig. 301. — The life history of the golden-eyed lacewing {Chrysopa oculata): 
a, eggs; 6, the larva — "aphis-lion"; c, foot of the larva; J, the larva seizing an aphid; 
e, the pupal cocoon; /, g, h, the adult; A, natural size (after Chittenden, Div. Ent., 
U.S. Dept. Agr.). 



292 



PRAIRIE COMMUNITIES 



small circular openings on the abdomen can often be seen sticking to 
the food plant (Fig. 300). The aphis-lion, which is the larva of the 
golden-eyed lacewing, feeds upon them (Fig. 301). The eggs of the 
lacewing are peculiar in that each is attached to a stalk. This is 
supposed to be an adaptation preventing the larvae already hatched 
from devouring the remaining eggs. The larva of the syrphus fly 
{Mesogramma sp.) (Fig. 302) devours the aphids in numbers. Lady- 
beetles, both adults and larvae {Hippodamia parenthesis Say, Megilla 
maculata) (Fig. 303), eat aphids. 

In June the narrow leaf-bug {Miris dolohratd) and the dark leaf-bug 
{Horcias goniphorus) are usually very abundant; both are characteristic. 




Fig. 302.^A syrphus fly {Mesogramma polila), adult (after Forbes): a, the 
larva which feeds on aphids; b, pupa; enlarged as indicated (from Forbes after 
Riley and Howard, Div. Ent., U.S. Dept. Agr.). 



Later in the season their places are taken by several others (Lygus 
pratensis and Adelphocoris rapidus). The garden flea-hopper {Halticus 
uhleri) occurs on the under side of leaves. The squash-bug family is 
represented by Alydus conspersus. 

The tree-hoppers are represented by the buffalo tree-hopper {Ceresa 
hubalus), and the curve-horned tree-hopper (Campylenchia curvata). 
The only lantern-fly recorded is Amphiscepa hivUtata. Leaf-hoppers are 
numerous; about ten species have been taken. 

The species of Orthoptera are mainly different from those of the low 
prairie. The 2-lined and short-winged brown locusts still continue. 
Xiphidium strictum (Fig. 304) takes the place of fasciatum. The com- 
mon meadow grasshopper {Orchelimum vulgare) and an occasional Texas 



HIGH PRAIRIE 



293 



katydid {Scudderia texensis) are taken from the goldenrod. From the 
goldenrod we also take the goldenrod beetle {Trirhabda tormentosa 
va,T. canadensis) and the case-bearer (Pachybrachys). The lady-beetles 
(Cydoneda, Hippodamia, Megilla, etc.) are common. The clover-leaf 
beetle (Languria mozardi?) (Fig. 305) is also of common occurrence. 
The snout-beetles are represented by the large, elongated Lixus (Fig. 
306), the larvae of which feed in the stalks of rank weeds. 




Fig. 303. — ^The lady-beetle {Megilla maculata DeG.) and its life history: a, larva; 
6, pupa; c, adult (Chittenden, U.S. Dept. Agr.); enlarged as indicated. 




Fig. 304.- 
(after Forbes). 



-Meadow grasshopper {Xiphidium sirictum Scud.); twice natural size 



The onioii-fly occurs in connection with the prairie onion. Eristalis 
tenax is common on the flowers. Various flower-flies occur. Waiting 
in the flowers for such animals as may come are the ambush-bugs {Phy- 
mata erosa fasciata), and the crab spiders (Misumessus asperatus and 
Runcina aleatoria). The jumping spiders (Phidippus podagrosus) are 
also predatory (138). The orb-weavers (Epeira trivittata, Agriope 
trijasciata) build webs into which many insects fall. 



294 



PRAIRIE COMMUNITIES 








Fig. 305. — ^The clover-stem borer {Languria tnozardi Lee) : a, the egg; b, c, the 
larva; <i, the pupa; e, the adult; much enlarged (after Folsom from Forbes). 



PRAIRIE ANIMALS 

III. General Discussion 



295 



One of the striking peculiarities of the prairie formation is the almost 
complete cessation of life activities of all the smaller animals in winter. 
In this respect the prairie animals follow the plants. In spring we find 
chiefly the insignificant seedling that has sprouted from bulb or seed, 
and the nymph that has just hatched from the egg. As the season 
advances the plants become adult, the majority of these reaching 
maturity with the animals in midsummer. 




Fig. 306. — ^The dock curculio {Lixus concavus Say) : a, adult; h, egg; c, d, newly 
hatched and full-grown larva; e, pupa; /, tip of pupa from above; about twice natural 
size (from Forbes after Chittenden, Div. Ent., U.S. Dept. Agr.). 



The low prairie is of interest because of its relation to the eastern 
forest region. Many if not most of the low prairie forms probably 
originally occurred in the marshes of the eastern forest region and the 
river-bottom swales of the prairie and great plains. Many of them 
(such as place their eggs into plants) are quite independent of the ground, 
and therefore are most likely to survive under conditions of cultivation 
where mesophytic plants are favored and the cultivation of the soil 
does not interfere with their activities. 



296 



PRAIRIE COMMUNITIES 



TABLE LXV 
Low Prairie Animals Inhabiting the Ground 
R = Riverside (Station 48); W = near Wolf Lake (near Station 45); J = south of 
Jackson Park (Stations 42, 43). 



Common Name 


Scientific Name 


Habitat 


Crayfish 


Cambarus diogenes Gir 


R 
R 
R 
R 
R 
R 
R 
R 

R 


J 
J 
J 
J 
J 
J 




Crayfish 


Cambarus gracilis Bun 




Ground beetle 


Chlaenius aestivus Say 




Ground beetle 


Platynus affinis Kirby 




Ground beetle 


A mar a angustata Say 




Spider 


Ozyptila conspurcata Thor 

Diplochila laticoUis Lee 

Salda coriacea Uhl 




Beetle 




Shorebug 




Salamander 


AmUystoma tigrinum Green 

Rana pipiens Sch 




Frog 


W 


Cricket-frog 


A oris gryllus Lee 


W 


Swamp tree-frog 

Toad 


Chorophilus nigritus Lee 

Bufo lentiginosus Shaw 

Thamnophis radix B. and G.?. . . 


w 
w 


Garter-snake 









TABLE LXVI 
Low Prairie and Temporary Marsh Animals Frequenting the Vegetation 
B = the triangular bulrush belt about Wolf Lake (Station 45); S = the sedge 
belt of the same; J=sedge prairie south of Jackson Park (Stations 42, 43); R = sedge 
prairie near Riverside (Station 48), June 15 to August 30. 



Common Name 



Scientific Name 



Habitat 



Spider 

Diving spider 

Spider 

Long-bodied spider. . . . 

Crab spider 

White crab spider 

Striped spider 

Garden spider 

Small orb-weaver 

Tube- weaver 

Slender meadow grass- 
hopper 

Short-winged brown lo- 
cust 

Meadow grasshopper . . 

Red-legged grasshopper 



Eugnatha straminea Em 

Dolotnedes sexpunctatus Htz. . . 

Epeira trivittata Key 

Tetragnatha laboriosa Htz 

Runcinia aleatoria Htz 

Misutnena vatia Clerck 

Argiope irifasciata Forsk 

Argiope aurantia Luc 

Epeira trifolium Htz . 

Agelena naevia Walck 

Xiphidiutn fasciatum DeG .... 

Stenobothrus curtipennis Harr. . 

Orchelimum vulgare Harr 

Melanoplus femur-rubrum DeG 



B 








B 








B 


S 


T 




B 


S 


T 






s 


J 

J 
J 




B 


s 


J 
J 




B 


s 


J 


R 




s 


J 


R 




s 


J 






s 


J 


R 



PRAIRIE ANIMALS 
TABLE IXm.— Continued 



297 



Common Name 



Texas grasshopper .... 

Cockroach 

Cricket 

2-lined locust 

Green-legged locust . . . 

Capsid bug 

6-spotted leaf-hopper . . 

Large leaf-hopper 

Damsel-bug 

Leaf-hopper 

Leaf-hopper 

Leaf- hopper 

Leaf-hopper 

Tarnished plant-bug. . . 

Brownie bug. 

Dusky plant-bug 

Leaf-hopper 

Ambush-bug 

Long-homed leaf-beetle 
Comroot worm-beetle 
Marsh snout-beetle. . . 

Buprestid 

Leaf-beetle 

Click-beetle 

Green beetle 

Chrysomelid 

Chrysomelid 

Case-bearer 

Milkweed beetle 

Goldenrod beetle .... 

Snout-beetle 

Fly 

Cloudy- winged fly . . . 

Long-legged fly 

Syrphus fly 

Onion-fly 

Ant 

Syrphus fly 

Bee 

Bumblebee 

Lacewing 

Ant 

Ichneumon fly 

Moth 

Syrphus fly 

Social wasp 



Scientific Name 



Scudderia texensis S. and P. . 

Blatlid sp 

Nemobius maculatus Blatch. . 
Melanoplus biviUatus Say. . . . 
Melanoplus viridipes Scud ... 

Teratocoris discolor Uhl 

Cicadula sexnotata Fall 

Draeculacephala mollipes Say . 

Reduviolus ferus Linn 

Chlorotetlix unicolor Fitch. . . . 
Helochara communis Fitch . . . 

Alhysanus striolus Fall 

Chlorotetlix tergala Fitch 

Lygus pratensis Linn 

Campylenchia curvata Fab . . . 
Adelphocoris rapidus Say. . . . 
A thy sarins parallelus Van D . . 
Phymata erosa fasciata Gray . 

Donacia subtilis Kunze 

Diabrotica 12-punctala Oliv . . 

Endalus limatulus Gyll 

Acmaeodera pulchella Hbst. . . 
Monachus saponalus Fab. ... 

Melanokis fissilis Say 

Chrysochus auratus Fab 

Nodonota tristis Oliv 

Typophorus canellus alerrimus 

Oliv 

Cryplocephalus venustus Fab. 
Cryptocephalus cinctipennis 

Rand 

Tetraopes telraophthalmus Forst 
Trirhabda canadensis Kirby. . 

Desmoris scapalis Lee 

Telanocera umbrarum Linn . . . 
Tetanocera plumosa Loew .... 

Dolichopodidae sp 

Syrphus americanus Wied .... 

Tritoxa flexa Wied 

Formica subpolita neogagates 

Emery 

Eristalis tenax Linn 

Agapostemon viridulus Fab. . . 

Bombus separatus Cress 

Chrysopa albicornis Fitch 

Myrmica rubra scabrinodis Nyl. 

Ichneumon galenus Cress 

Scepsis fulvicollis Hbn 

Meso gramma geminala Say. ... 
Polistes variatus Cress 



HabiUt 





S 








S 








s 








s 




R 
R 




s 






B 


s 






B 


s 






B 


s 






B 


s 






B 


s 








s 








s 






B 


s 








s 






B 








B 


s 




R 


B 








B 


s 






B 


s 




R 




s 








s 








s 






B 






R 


B 










s 








s 








s 






B 










s 








s 







298 



PRAIRIE COMMUNITIES 



TABLE LXVII 
Animals Usually Common on Compass-Plant Prairie 
Collections made near Riverside (Station 48) and Chicago Lawn (Station 47), 
June 15 to August 30. 



Common Name 



Scientific Name 



Cricket 

Jumping spider 

Jumping spider 

Jumping spider 

Jumping spider 

Harvestman 

Garden spider 

Ant 

Grasshopper 

Meadow grasshopper 
Meadow grasshopper 

Brown locust 

Conehead 

Katydid 

Leaf -hopper 

Leaf-hopper 

Leaf -hopper 

Leaf-bug 

Leaf-bug 

Leaf-hopper 

Membracid 

Garden flea-hopper . . 

Stinkbug 

Leaf-bug 

Leaf -hopper 

Leaf -hopper 

Negro-bug 

Coreid 

Stinkbug 

Leaf -bug 

Leaf -bug 

Beetle (Mordellid) . . 

Lady-beetle 

Case-bearer 

Strawberry beetle . . . 

Beetle 

Syrphus fly 

Green snake 



Nemobius fasciatus villaius Harr. 

Maevia niger Htz. 

Phidippus podagrosus Htz. 

Phidippus boreaiis B. 

Phidippus rufus Htz. 

Liobunum grande Say 

Argiope trifasciata Fors. 

Formica cinerea var. neocinerea Wheeler 

Orphulella speciosa Scud. 

Orchelimum vulgare Harr. 

Xiphidium strictum Scud. 

Stenobolhrus curtipennis Harr. 

Conocephalus ensiger Harr. 

Scudderia texensis S. and P. 

Athysanus striolus Fall. 

Agallia 4-punctata Prov. 

Platymetopius acutus Say 

Trigonotylus ruficornis Four. 

Miris dolabrata Linn. 

Chlorotettix spatulata O. and B. 

Stictocephala lutea Wlk. 

Halticus uhleri Giar. 

Euschisius variolarius Pal. Beauv. 

Plagiognathus politus Uhl. 

Eutettix straminea Osb. 

Empoasca mali LeB. 

Thyreocoris pulicaria Van D. 

Alydus cons per sus Mont. 

Cosmopepla carnifex Fab. 

Garganus fusiformis Say 

Horcias marginalis Reut. 

Mordellistena connata Lee. 

Cycloneda sanguinea munda Say 

Pachybrachys sp. 

Typophorus canellus gilvipes Horn 

Photinus punctulatus Lee. 

Eristalis tenax Linn. 

Liopeltis vernalis Harlan 



CHAPTER XV 

GENERAL DISCUSSION 

I. Introduction 

We have briefly presented some facts regarding the nature and 
environmental relations of animals, an account of the environment, and 
a discussion of the inhabitants of some of the type habitats of the forest 
and forest border regions. We noted also in preceding chapters some 
aspect of relations of the animals of the same and of different com- 
munities to one another, and our relations to them. We may still 
present (a) the relations of the different communities to one another, 
(b) the laws governing distribution, and (c) a discussion of the relations 
of ecology to broader geographic problems. 

II. Application of the Laws Governing Animal Activities to 
World and Regional Problems 

As was stated in the first chapter, the relative importance of different 
environmental factors is not definitely known, but probably in local and 
experimental conditions, land environments can best be measured in 
terms of evaporating power of the air, light, and materials for abode, 
aquatic environment by carbon dioxide, oxygen, and materials for abode. 
In explaining extensive or regional distribution, a few factors have 
been emphasized and these usually in the sense of barriers. Merriam 
(48) emphasizes temperature. Walker (128) atmospheric moisture. 
Heilprin (192, p. 39), like most paleontologists, emphasizes food. 
Nothing is, I believe, more incorrect than the idea that the same single 
factor governs the regional distribution of most animal species. Since 
the environment is a complex of many factors, every animal, while in 
its normal environmental complex, lives surrounded by and responds 
to a complex of factors in its normal activities (44, p. 193). Can a 
single factor control distribution? 

I. reactions to single factors 
Considerable physiological study of organisms has been conducted 
with particular reference to the analysis of the organism itself, but with 
little reference to natural environments. Many of the factors and con- 
ditions employed in such experiments are of such a nature that the 

299 



300 ECOLOGY 

animal would rarely or never encounter them in its normal life. Other 
experiments are attempts to keep the environment normal, except for 
one factor (44, p. 180). These have demonstrated that animals are 
capable of responding to the action of a single stimulus. 

A typical experiment to demonstrate this would consist in preparing 
two long receptacles in such a way that one is the normal environment 
of the animals in all respects and the other in all respects except for 
one factor, as, for example, temperature. The temperature conditions 
of the latter might be as follows: temperature at one end 10° C, at the 
other 35° C, with a gradient between. If then 100 animals are placed 
in each of the receptacles, those placed in one end of the gradient will 
soon show signs of stimulation and will move about until they come 
near the center of the pan where the temperature is 2o°-25°. If, after 
sufficient time has elapsed for the experimental animals to take up this 
position, the control animals have remained equally distributed, the 
experiment will show that the animals have responded to temperature 
alone. 

Certain general laws govern the reaction of animals to different 
intensity of the same stimulus. Take, for example, temperature. 
There is in most animals which have been subjected to experimentation 
with temperature a range of several degrees within which the activities 
of the animal proceed without marked stimulative features, as is sug- 
gested by the experiment outlined above. Conditions within this 
range of several degrees are called the optimum. As the temperature 
is raised or lowered from such a condition, the animal is stimulated. 
If the temperature is continuously raised, a point is reached at which 
the animal dies. The temperature condition just before death occurs 
is called the maximum (35). The lowering of temperature produces 
comparable results. 

2. EXPERIMENTAL STUDIES OF HABITAT SELECTION 

Animals select their habitats, and distribution is the result of this 
selection. To decide whether or not one factor can determine distri- 
bution, experiments, of which the following is a typical example, have 
been performed. 

a) Methods of experimentation. — Do animals select their breeding- 
places ? To answer this question, ti^er-beetles were selected as material 
and adults were placed in cages containing soil of several kinds. Each 
kind was so arranged into steep and level parts, that about one square 
foot of each type was exposed. The adults placed in the cage were 



ACTIVITY AND DISTRIBUTION 



301 



taken when the species was breeding (see p. 2 1 2) . The soil was kept very 
moist up to the time the first ovipositor holes were made, because this 
species lays only in moist soil. After this the wetting of the soil was 
done very cautiously, so as not to wash the eggs from the ground in 
steep parts. Accordingly, the holes were not obliterated from day to 
day. The counts, however, are not accurate for the soil in which a large 
number were made, because eggs are sometimes laid very close together 
and adjoining holes destroyed. Some eggs are deposited in irregular 
cracks and crevices where they are likely to be overlooked. The greatest 
care was taken to discover every hole made in the soils in which larvae 
do not occur in nature. Soils in the different lots were arranged in 
different orders. 

b) Results. — Table LXVIII shows the approximate number of holes 
made in the clay and probably the actual number made in the other 
soils, together with the number of larvae which appeared: 80 per cent 
on the steep slope, 98 per cent in clay. 

The count of holes includes some in the first stages of digging, mere 
scratches on the ground, and others which had been excavated to the 
usual depth with or without eggs being laid. 

TABLE LXVIII (55) 

Distribution of Ovipositor Holes and Larvae or C. purpurea limbalis under 
Experimental Conditions 
S = steep; L= level. 





Clay 


Clay, 9 Pts. 
Humus, i Pt. 


Forest 
Humus 


Humus, i Ft. 
Sand, 9 Pts. 


Clean 
Sand 




s 


L 


s 


L 


S 


L 


S 


L 


S 


L 


T ^^ T /Holes 

L°^I \Larvae 

T ««■ TT /Holes 

T«* ttt/HoIcs 

L°^"nLarvae 




9 
21 
12 
17 
24 





5 
I 

7 
10 






















c 














































c) Factors controlling habitat selection (55). — Pairs taken in coitus 
were placed in cages containing sand only and level clay only. No 
larvae appeared in either case. The experiment with the level clay 
has not been repeated. Females placed in cages containing rough, 
steep clay, deposited eggs. Eggs are also absent from dry soils, whether 
steep or level. 



302 ECOLOGY 

Slope, kind of soil, and soil moisture are factors governing the 
deficiency or absence of eggs. A deficiency or excess in any one of 
these respects decreases the number of eggs laid, or causes them not to 
be laid at all. The animals are in the condition for egg-laying for but a 
short period. 

d) Method of selection. — It has been determined by opening holes 
that eggs are not laid in all, and in one case the first holes made by the 
female were empty. This would tend to show that the female beetle 
tries the soil before laying the eggs, but I have not been able in other 
cases to determine whether the first holes contained eggs or not. To 
determine this, it would be necessary to watch a female all of the time 
during several days. 

3. LAW OF TOLERATION (55) 

Repeated experiments with several species have shown results 
similar to those shown in Table LXVIII, and we have concluded that the 
egg-laying place of the tiger-beetles is their true habitat. The tiger- 
beetles which lay eggs in soil do so only when the surrounding tempera- 
ture and light are both suitable, the soil moist and probably also warm. 
The soil must satisfy the ovipositor (egg-laying organ) tests with respect 
to several factors. Egg-laying, the positive reaction, is then probably 
a response to several factors. Furthermore, after the eggs are laid, the 
conditions favorable for egg-laying must continue for about two weeks 
if the eggs are to hatch and the larvae reach the surface. The success 
of reproduction depends upon the qualitative and quantitative com- 
pleteness of the complex of conditions. This complete complex is called 
the ecological optimum. The negative reaction, on the other hand, appears 
to be different. The absence of eggs, the number of failures to lay, and 
therefore the number of eggs laid in any situation, can be controlled by 
qualitative or quantitative conditions with respect to any one of several 
factors. The presence, absence, or number of eggs laid may be governed 
by a single factor. 

For example, all other conditions being optimum, moisture may 
control the presence, absence, or number of eggs laid. If the moisture 
be optimum, the maximum number of eggs will be laid. If it is too 
great few or no eggs will be laid. This factor then controls according 
as it is near the optimum, or near either the maximum or minimum 
tolerated by the species. It is, however, not necessary that but a single 
factor should deviate; the effect is similar or more pronounced if several 
vary. 



LAW OF TOLERATION 303 

The success of a species, its numbers, sometimes its size, etc., are 
determined largely by the degree of deviation of a single factor (or 
factors) from the range of optimum of the species. It is obvious that 
the cause of the fluctuation might be, for example, moisture due to 
(climatic) deficiency in rainfall, or rapid run-off, due to steep slope. 
The evidence for the application of the law of toleration to local distribu- 
tion is good. Since the same factors are involved in the "geographic" 
or more extensive distribution, there is no difficulty in the application 
of the law to such distribution also, for, to assume that the law is not 
applicable is to assume that animals distinguish between the causes 
which lie back of the changes in physical factors by which they are affected. 
The fact that, in so far as our observation can go at present, most animals 
are found in similar conditions throughout their ranges is also good 
evidence for the application of both the laws of minimum and toleration 
to problems of geographic range. In fact, the law of minimum (see p. 68) 
is but a special case of the law of toleration. Combinations of the factors 
which fall under the law of minimum may be made, which make the law 
of toleration apply quite generally. For example, food and excretory 
products may be taken together as constituting a single factor. From 
this point of view the law of toleration applies, the food acting on the 
minimum side, excretory products on the maximum. 

4. APPLICATION OF THE LAW OF TOLERATION TO DISTRIBUTION (55) 

As has already been implied, the locality or region of optimum, or 
the locality or region in which the animal is most nearly in physiological 
equilibrium, is called the habitat (ecological optimum) when it refers 
to ecological or local distribution, and the center of distribution when it 
refers to extensive areas. The so-called centers of distribution are 
often only areas in which conditions are optimum for a considerable 
number of species. The distribution and number of individuals of any 
species may be graphically represented as below: 

Minimum Limit of tjo„„„ «f n,^t;.„,.«. Maximum Limit of 



Tokrat^n^ "' 1 ^^^^^ «* Optu.^,m 



Absent 



<-«< Habitat or center of distribution 

Decreasing Greatest abundance 



Toleration 



Decreasing 



Absent 



On account of the nature and distribution of climatic and vegetational 
conditions, it follows that as we pass in one direction from a center, one 
factor may fluctuate beyond the range of toleration of a species under 
consideration; but as we pass in another direction the fluctuating 
factor is very likely to be different. 



304 ECOLOGY 

a) Governing the limit of local and geographic range. — The geographic 
or local range of any species is limited by the fluctuation of a single 
factor (or factors) beyond the limit tolerated by that species. In non- 
migratory species the limitations are with reference to the activity which 
takes place within the narrowest limits (usually breeding). In migratory 
species this activity limits the range during only a part of the life history. 

b) Governing the distribution area and habitat area (55). — The dis- 
tribution area of a species is the distribution of the complete environ- 
mental complex in which it can live, as determined (i) by the activity 
which takes place within the narrowest limits and the animal's power 
of migration, and (2) by barriers in which some factor of the complex 
fluctuates beyond the limits of toleration of the species in all periods of 
its life history. 

If these statements are borne out by further investigation it follows 
that every study of animal behavior which is related to measured physical 
factors or to natural environments is directly related to problems of dis- 
tribution. 

III. Agreement between Plants and Animals 

In recent years the ecology of plants has received much attention 
and the subject has made great progress. In animal ecology but little 
progress has been made, and students (and teachers) have been inclined 
to expect relations and conditions in animals parallel with those in plants. 
Little progress has been made, largely because workers have not recog- 
nized the important phenomena in animals as compared with plants. 

I. ecological agreement of individuals 
Organisms may be divided on the basis of their ability to move 
about, into sessile or fixed, and motile forms. All organisms are of course 
capable of movement of some sort, even though it be only mechanical 
movement dependent upon turgor. There are also all degrees of ability 
to move from place to place. Some motile plants and animals move 
about only very slowly, and the division of organisms into sessile and 
motile is a somewhat artificial classification, as many forms are difficult 
to place in either group. Some are sessile at one period of their lives 
and motile at another. Comparable difficulty arises, however, in the 
separation of plants from animals. 

The animals with which we, as inland people, are most famih'ar, 
are the highly motile forms, and the plants with which we are most 
familiar are sessile forms. We are all also somewhat familiar with 



AGREEMENT OF COMMUNITIES 305 

numerous marine animals, such as polyps, sea plumes, etc., which are 
sessile, like plants. Sessile animals are probably all aquatic. Logically, 
ecology cannot be divided into plant and animal ecology, but it may be 
divided into the ecology of sessile and motile organisms. 

An appreciation of the likenesses and differences of sessile and 
motile organisms is an important thing in ecology. The plant and the 
animal groups contain both sessile and motile types together with types 
intermediate between the two and thus taken as a whole plants and 
animals are in agreement in the matter of response. However, since the 
vast majority of animals with which we deal are motile, their activities 
are evident because of their ability to move about. On the other hand 
the majority of plants are sessile, and sessile individuals usually can 
change the position of the whole or its parts only by growth. Changes 
in the relation and character of parts are the results of the application of 
stimuli to sessile plants. Movement is the chief result of the application 
of stimuli to animals. Animal ecology has very much in common with 
plant ecology. Diatoms, flatworms, and many other marine animals 
and plants meet the same conditions in the same or similar ways (72, 
p. 121; 53a, p. 156; 53^, p. 15s). Sessile animals, such as reef-forming 
corals, show growth form differences (193, 194, 195) under different 
conditions, just as sessile plants do. Comparable plants and animals 
show comparable responses. The physiological life history aspect of 
plant ecology (52) is parallel with the same phenomenon in animals, 
but the activities of motile animals correspond roughly to the growth 
form phenomena in sessile plants (55, p. 593). 

All the way through the study of ecology we look for behavior or 
activity difference in motile organisms (chiefly animals), when con- 
sidering the species of two different habitats, while, when making a 
comparison of the sessile organisms (chiefly plants) of two habitats, 
we look for differences in form and structure. To be sure an occasional 
sessile plant can move some of its parts and likewise some motile animals 
change color, size, or form with differing conditions during development, 
but these are of secondary rather than primary importance and we must 
look mainly to form changes as "plant response" and behavior, or activity 
changes as "animal response." 

2. AGREEMENT OF COMMUNITIES 

Are physical conditions sometimes similar when vegetation and 
landscape aspect are very different ? That they are is clearly suggested 
when we compare the forest and the shrub-covered bluff where forest 



3o6 ECOLOGY 

animals occur. Plants grow from seeds only under a very limited range 
of conditions. However, if trees are given a few years' growth under 
favorable conditions they will be successful under a great range of con- 
ditions. The great age to which trees often live and the slowness with 
which they grow make it possible for conditions to change while the 
trees still live on with changes only in leaf structure. It is to be expected 
that the distribution of animals is correlated with the occurrence of 
seedlings or of quick-growing plants or at least with leaf structure types 
rather than strictly with species of trees. These facts suggest that 
there are two types of cases in which physical conditions and forest 
conditions are not in accord. In the first case atmospheric conditions 
become favorable for forest animals before any woody plants have been 
able to grow; in the second, woody plants remain after conditions have 
become unfavorable for forest animals; both are due to lagging behind 
of vegetation ; both are very local and of minor significance. 

The reasons for the wide distribution of some animals in the forest 
stages which we have considered are no doubt vaiious. For example 
Zonitoides arboreus (Table L, p. 252) is rare in the early stages and is 
confined to the lower and moister localities. If Epeira domicilorum is a 
species of stable physiological makeup we can offer no explanation for 
its peculiar distribution (Table LVI, p. 257). A species may have its 
critical period in the early spring when the leaves are off the trees and 
the condition of the atmosphere similar in all stages (see Fig. 251, p. 248) 
or may live at higher levels in the denser and older stages, and thus be 
surrounded by similar atmospheric conditions, but we are not warranted 
in assuming either of these causes here. 

Another striking feature of the distribution of many beetles, bugs, 
spiders, and Orlhoptera is the fact that they are found in open woods, 
edges of woods, on the vegetation of marshes, and over the water of small 
ponds in which vegetation is growing. In this way many species are 
found to occur in what at first appear to be very unlike situations. 
Lygus pralensis, Triphleps insiduosus, and Euschustus variolarius, 
which occur on the vegetation of the margins of swamps, of the 
black-oak forest dunes, and on prairies and agricultural lands, may 
serve as examples. Shull has pointed out similar facts as one of the 
difficulties in the way of ecological classification of Orlhoptera and 
Thysanoptera. Such species as the bugs mentioned above are said to 
occur "everywhere," although they are rarely found in moist woods or 
in any situation in which they are not fully exposed to the sun and 
may always live in similar conditions. 



AGREEMENT OF COMMUNITIES 307 

Some investigators have questioned the importance of vegetation 
to animals and we note here that the distributions of plant and animal 
species are not always correlated. If one refers to species of plants 
and species of animals then the vegetation very often is not correlated 
with the distribution of the animals. If on the other hand one means 
that the plants are controllers of physical conditions, then vegetation 
can be said to be of very great importance. 

Before discussing the problem of agreement between plant and 
animal communities, it is necessary to state what is meant by agreement. 
According to present developments of the science of ecology plant and 
animal communities may be said to be in full agreement when the growth 
form of each stratum of the plant community is correlated with the conditions 
selected by the animals of that stratum. Questions of agreement are pri- 
marily questions for experimental solution. Two types of disagreement 
are to be expected. We may illustrate the first by a bog or marsh 
community. Considering plants rooted in the soil we note that water 
is secured from the soil by the roots and is lost through the leaves and 
twigs. Accordingly since bog soil is unfavorable, due to the presence 
of toxins or to other causes, plants growing in it do not secure water 
easily even when the quantity of soil water is great. Such plants have 
xerophytic structures (which tend to check the loss of water) developed far 
beyond the requirements of the atmospheric conditions surrounding their 
vegetative parts. It is improbable that the animals inhabiting a bog- 
vegetation field stratum would select atmospheric conditions such as 
produce equally xerophytic structures under favorable soil conditions. 
We may therefore expect disagreement. The smaller plants such as 
fungi, algae, etc., are related to the strata of soil and atmosphere exactly 
as the smaller animals and as much disagreement is to be expected between 
such plants and the rooted vegetation as between the rooted vegetation 
and animals. It must also be noted that the xerophytic structures of 
the plants of unfavorable soils may have important influence upon ecto- 
phytic plants and animals and in part counteract the effect of favorable 
atmospheric conditions. 

The second type of disagreement is represented by cases in which 
the vegetation lags behind. We have already noted that on the clay 
bluff pp. 209-(i7) conditions become favorable for inconspicuous plants 
and forest animals as soon as the growth of the pioneer vegetation gives 
shade to the soil. In other cases woody vegetation remains in situations 
where the conditions have become unfavorable for it and the less con- 
spicuous plants and some of the animals have disappeared. We may 



3o8 ECOLOGY 

expect lack of accord within and between plant and animal communities 
under such conditions. In these cases, however, conditions are onl>^ 
temporarily out of adjustment, due to rapid physiographic changes, and 
we note from the data presented that plant and animal communities 
are usually in agreement. The exceptions are often apparent only and 
due to the emphasis of species instead of mores and growth form. P'rom 
this viewpoint and with such exceptions as are noted, plant and animal 
communities are probably in agreement the world over. 

IV. Relations of Communities 

I. SUCCESSION — CAUSES 

Succession is no doubt one of the most important and widespread 
of the phenomena discovered by the ecologists up to the present time 
(120, 197). Simply stated, it means that on a given fixed area organisms 
succeed one another, because of changes in conditions. These changes 
make impossible the continued existence of the forms present at any 
given time; with the death or migration of such forms, others adapted to 
the changed conditions occupy the area, whenever such adapted forms 
are available. The changes referred to result from physical or bio- 
logical causes, or combinations of the two. It is probable that the causes 
of the changes are frequently complex combinations of various factors. 

We have among the physical causes changes in climate and changes 
in topography. All degradation of land is a cause of succession. Such 
geological processes are well understood and treated in textbooks on 
geology and physiography. 

The biological causes of succession b'e chiefly in the fact that organ- 
isms frequently so affect their environments that neither they themselves 
nor their offspring can continue to live at the point where they are now 
living. Every organism adds certain poisonous substances to its sur- 
roundings, and takes away certain substances needed by itself. It 
frequently thus so changes conditions that its offspring cannot live and 
grow to maturity in the same locality as the parents. However, by 
these same processes it prepares the way for other organisms which can 
live and grow in the conditions thus produced. 

Obviously, those organisms whose decaying bodies and excretory 
materials are not removed or distributed by their wanderings will 
modify their environments most. Organisms which remain in one 
place do nothing which tends to remove the results of their own existence, 
and frequently modify their environments in manners detrimental to 



CONVERGENCE 309 

themselves."^ On the land, plants are the dominant sessile forms, and 
often profoundly modify the conditions in which they live, so that they 
cannot succeed themselves. When will the process of succession stop ? 
Obviously, it must cease when there are no available species to take the 
places of those which have destroyed their own habitats. There are 
species which are immune to their own products and the products of the 
species which are associated with them. Obviously, when a condition 
in which these species can live is reached, and they come to occupy the 
place which is thus made ready for them, the formation which they 
constitute can, so far as the plants are concerned, last indefinitely. This 
is theoretically true of all climax or geographic formations, and has been 
established for the beech and maple forest of eastern America. 

2. MOTILE AND SESSILE ORGANISMS IN SUCCESSION 
Motile Organisms Fixed Organisms 

a) Motile organisms aflfect their own a) Sessile organisms modify their 
environments by the destruction own environments largely through 

of materials of abode and food growth of their own bodies, cutting 

supply and the pollution of their off light, interfering with circula- 

habitats by waste products (196, tion in surrounding medium and 

114, and citations). accumulation of waste products 

(iQS, 120). 

h) The changes under (a) make the h) The same as for motile organisms 
continued existence of the group (197). 

in question impossible and pre- 
pare the way for other differently 
adapted (succession) forms. 

c) Succession is a succession of c) Breeding and living places are not 
breeding-places. contrasted as young stages usually 

thrive only where adults can live. 
Succession can take place only where forms adapted to the changed 

conditions are available. 

3. CONVERGENCE 

The work of running water, for example, is in a measure convergent. 
When a new body of land is uplifted, streams begin to work their way 
into the new land mass and cut deep valleys. The formation of numer- 
ous tributaries (92 and citations) isolates portions of the upland in the 

' In the sea (195) sessile forms are chiefly animals and animals are probably the 
chief cause of succession there. Coral polyps cannot build upward indefinitely, as 
they soon reach the surface and can no longer exist. By reaching the surface they 
prepare the way for other forms. 



3IO 



ECOLOGY 



SAND RIDGE 
Cottonwood 
Gray pine 

Black oak 



CLAY BLUFF 
Aspen 
Cottonwood 



White oak 



Red oak 



Hop-Hornbeam 
White oak 
Red oak 



Hickory Hickory 

BEECH AND SUGAR MAPLE 

Tulip Hickory 

Basswood Red oak 



White elm and 
White ash 

Swamp white oak 
Buttonbush 
Cattail and Bulrush 



Water-lily and Water 
MiU-foil 



Bur oak 

Basswood 
Hawthorn 



Slippery elm and 
White elm 



Chara 



POND 



River maple 



Black willow 



FLOOD-PLAIN 



Diagram 8. — Showing the convergence of four types of habitat, to the beech 
and maple forest. Read from the extremities toward center. (Prepared with the 
assistance of Dr. Cowles and from his writings.) 



CLIMATIC COMMUNITIES 



3" 



form of hills. These hills are broken up into smaller hills by the smaller 
tributaries, and the resulting hills into still smaller ones, until the upland 
is all removed and the country reduced to a generally level condition 
known as a peneplain. The process of peneplanation then tends to 
fill all low lakes and ponds and drain all high ones. It works over all the 
materials of the upland and lays them down as alluvial deposits, which 
process tends to make the surface materials of a uniform nature. Asso- 
ciated with this, and more or less independent of it, the process of plant 
succession makes the conditions coverging (Diagram 8) to a still greater 
degree (13). 

The principle of convergence, while not generally established, is 
believed to be of wide application. It has been suggested for the tropical 
forest of the Philippines by Whitford (198), for the coniferous forest 
regions of North America by Adams and by Gleason, and for the arid 
Southwest by Ruthven. Theoretically at least, in all the varied types of 
land habitats of any large area, communities are tending toward some 
one type which is primarily adjusted to the climate of the region when its 
topography approaches base level. Such a climatic type of community 
rapidly displaces the communities of all the varied kinds of soil of a 
newly uplifted area which is only a few hundred feet above the sea. In 
these situations the climatic communities dominate sterile soil by process 
of successional development extending over a few score or hundreds of 
years. 

V. General Relation of Communities of the Same 
Climate (13) 

In each climatic realm of the world there are relations between 
communities of two sorts, (a) physiological relations, best defined as 
physiological similarities, and {h) successional or evolutionary relations. 
Diagram 9 shows both types of relations for the temperate American 
forest border area. Single-pointed arrows show the directions of suc- 
cession, double-pointed arrows show similarities of conditions and the 
occurrence of several or many of the same species in considerable num- 
bers in communities between which such arrows extend. Broken lines 
indicate less definite relations than the solid lines. Starting with the 
aquatic communities, we note that spring-fed and intermittent stream 
communities converge with physiographic aging to small, permanent, 
swift-stream communities, and permanent swift-stream communities 
are succeeded by base-level stream communities. The characteristic 



312 



ECOLOGY 



communities of small permanent streams and base-level streams are 
indicated above. Taking up another line, we note that the large-lake 
communities are succeeded by the small-lake communities. Rocky- 
shore communities of the large-lake areas have features in common with 
those of the rocky rapids of the stream. The sand, gravel, and vegeta- 
tion communities of the base-level stream and the small lake have many 
things in common, while the silt and humus bottom communities are 
distinguishing features of the two. Communities of ponds originating 



Sand 



s. 



<^--^ 





.^' 



\ ^*' 



5UC»i«' 



Sand -{-►Vegetation -*A, 
►Base Level Stream— .^j' 
Silt Bottom 



..<^^ 



-»Pond-Mi< iT ' Ui matte 

>^ ^*'"*'5r^Moist Forest Margin— ^•Forest Margin 
"**- ^ or Thicket ^or Thicket 



"^ Thickets- -^Thicket 



Spring Fed Brook — fc^ 



s-^ 



'^ 




^^ 



Diagram 9. — Showing some relations of the chief animal communities of the 
forest-border region of Central North America. The word community or communi- 
ties is to be understood as following all the words appearing in the diagram. For full 
description see text. 



by very rapid physiographic changes pass through a series of stages 
comparable to those found in the different parts of the small lake. The 
lake communities pass to the pond community stage or give rise to a 
floating-bog marsh community which is displaced by a floating-bog 
thicket community. Cowles states that this takes place in deep lakes,^ 
while the shallow ones become ponds which give rise to marshes with 
firm substrata. Such a marsh community may be displaced wholly 
by a low prairie community, in part by a thicket forest margin com- 
munity, or wholly by a thicket community which will be succeeded by 



CORRESPONDENCE OF CLIMATIC COMMUNITIES 313 

a forest community. In the savanna or prairie climate the marsh 
margin thicket may become a climatic thicket or forest margin. In the 
savanna or prairie climate the communities of all the various soils and 
the low pi;3,irie community may converge to the prairie climate com- 
munity, or to the forest community as is shown below for the forest 
climate. In the forest climate and locally in the savanna climate the 
communities of all the various soils pass through a thicket community 
stage (T), related to a climatic forest. The thicket communities of all 
the dry soils are related to the forest margin thicket community of the 
savanna climate. 

I. CORRESPONDENCE OF COMMUNITIES OF DIFFERENT PARTS OF 
THE WORLD (55) 

The botanists have abundant evidence for the correspondence of 
the formations of similar climates (58a). The vegetation of diflferent 
parts of the world which have similar climates is similar and the plants 
though usually belonging to different taxonomic groups are similar in 
growth, form, and appearance. Correspondence and similarity of 
vegetation is not limited to the climatic or extensive formations, but 
applies also to strictly local situations wherever the physical conditions 
are similar. On the animal side we have less trustworthy evidence of 
similarity or correspondence. If the physiological similarity occurs in 
the same community, due, as has just been stated, to selection of habitat 
and modification of behavior, we conclude that it occurs in all communi- 
ties occupying similar conditions and that similar situations in different 
parts of the world have physiologically similar communities, and identical 
situations approximately identical communities. 

The direct evidences for the correspondence of formations in different 
parts of the world are as follows: (a) the existence of identical or closely 
corresponding species has long been known to naturalists (3, 199, 192); 
{b) similarity of physiological life histories of many species is well known, 
as, for example, corresponding species in the United States and Europe 
or Japan, and a general concentration of breeding in the rainy season in 
all arid climates, etc.; (c) certain animals in similar environments in 
different parts of the world appear from the accounts of naturalists to 
behave alike with reference to the physical condition of different parts 
of the day, year, and different weather. For example, it appears that 
there is a close physiological and ecological similarity between certain 
antelopes of the savannas of Africa and certain savanna kangaroos of 
Australia (200). In other words certain kangaroos are ecologically and 



314 ECOLOGY 

physiologically similar to some antelopes. As has already been stated, 
the zoologist is usually unduly impressed with specificities such as mode 
of movement of limbs, body, etc. Now if my reader pictures an African 
antelope running gracefully from a pack of Cape hunting, dogs (102, 
pp. 119-23), and an old-man-kangaroo leaping from a pack of dingoes 
(202, pp. 41, 243), noting mainly the specific peculiarities of the movement 
of limbs and body of the pursued in each case, he will be dwelling upon 
specificities of little ecological significance and missing the point of view 
of the ecologist altogether. These specificities of behavior are matters of 
little ecological significance; it matters not if one animal progresses by 
sommersaults so long as the two are in agreement in the matter of reac- 
tions to physical factors as indicated by the manner of spending the day 
(200), avoidance of forests, swamps, cold mountain tops, etc., entirely 
available to them, and in the mode of meeting enemies as indicated by the 
reaction to the approaching hunter or enemy. 

a) Distribution of land communities represented in Central North 
America. — The following climatic formations are represented at Chicago 
and distributed as given below: 

Temperate Deciduous Forest Formations: Forest with broad, thin leaves which 

are shed in autumn; near Chicago, oak, hickory, beech, and maple (580). 

Distribution: Eastern North America, north to the Great Lakes; 

Chili, north to 35°; Europe, north of the Alps, and south of 60°; 

Japan and the vicinity of Okhotsk (58c) . 

Temperate Savanna Formations: Grasslands with scattered trees, or trees in 

groves surrounded by thickets, and with dense forests along larger streams. 

Near Chicago, the grassland is prairie and the trees chiefly oak and hickory. 

Distribution: A narrow belt in North America surrounding the great 

plains on the east, north, and west; Uruguay, South Australia, 

South Africa, and Eastern Siberia. 

Formations of Forests with Narrow Thick Leaves: Coniferous forest. Dense 

evergreen forests with little undergrowth. Lies just to the north of 

Chicago and was represented locally in the parts of Michigan shown on 

Map I (frontispiece). 

Distribution: North America north of the Great Lakes and Columbia 
River extending southward into the mountains; Eurasia north 
of 60°, extending southward into the mountains. 

The localities which are in agreement are indicated by distribution 
of the different types of formation. It will be noted that the deciduous 
forest animal formation with which we have dealt is found in several 
parts of the world, this animal community being essentially duplicated in 



ECOLOGY AND BIOLOGY 315 

these differently located areas. This correspondence is probably much 
more striking physiologically than in the matters of interrelation of 
species because in some formations certain groups, as, for example, 
antelopes in African steppes, are especially numerous, while in a 
corresponding situation in South America they are very few. 

As has already been suggested, correspondence is not limited to 
the gross characters of extensive formations, but is equally true of 
the more local communities. In matters of correspondence of species 
there are often striking correspondences within the groups of formation 
indicated above. For example, there is a striking correspondence in 
behavior between the meerkats of the steppes of East Africa (3) and 
the prairie dogs of our own steppe, both being grasslands but differ- 
ing in climate. Considering a local formation, as that of the sandy 
beaches of the sea and very large lakes, we note that along the New 
England coast and around the shores of Lake Michigan the moist, 
sandy beaches are inhabited by the larvae of the beach tiger-beetle 
{Cicindela hirticollis) (Fig. 134, p. 179). Along the Gulf Coast at Galves- 
ton, Texas, we find the larvae of C. saulcyi inhabiting almost identical 
situations, holes of about the same depth, etc., while Dr. Horn (203) 
describes a different larva in like situations and with like habits on the 
coast of India. 

Still, with all that has been said, matters of agreement of different 
animal communities in different parts of the world are largely theoretical, 
and while apparently logically well grounded, the general statement 
must be treated with due caution and subjected to experimental test 
as soon as possible. Such testing will involve careful experimental 
study of the communities of two like environments under rigidly con- 
trolled and carefully measured conditions. 



VI. Relations of Ecology to Other Biological Subjects 

The environmental processes which we are discussing are those in 
which organisms have existed since their origin on earth. The stresses 
and strains to which organisms have been subjected have been in the 
same direction for long periods. Now that we have learned much 
concerning organic response to environment, such as physiological 
response, behavior response, and structural response, we note at once 
that processes of adjustment and equilibration of living substance may 
bear important relations, on the one hand to environmental processes, 
and on the other to the physiological aspect of biological phenomena. 



3i6 ECOLOGY 

Ecological matters are then worthy of the attention of the student of 
morphology, heredity, and evolution. 

What is the significance in the fact that the white tiger-beetle 
(Cicindela lepida) belongs to the first association in the development 
of a forest community on sand, which we may say corresponds to a 
family, and to the subterranean ground stratum (corresponding to genus) 
and to the white tiger-beetle mores? Furthermore, that Cicindela 
lecontei and the green tiger-beetle {Cicindela sexguttata) belong respec- 
tively to different and older situations or associations ? We note that the 
habitats in which the species occur are characterized by distinctly differ- 
ent soils, moisture, amounts of shade and light. We note, furthermore, 
that these animals are possessed of unusual powers of flight and 
are able to select conditions suited to their physiological constitution. 
Their mores characters are definite characters, which can be measured 
in terms of reactions to measured complexes of physical and other 
environmental factors. They are as clearly defined as any morphological 
taxonomic characters and can be measured with the accuracy of any 
physical phenomena. 

Doubtless to the student of genetics or evolution, the question of 
the origin of such characters and their fixation in heredity is a leading 
question. At this point we know little or nothing. Since nearly all 
species have definite habitat preferences and since many varieties differ 
slightly from the related species form in the matter of habitat preference, 
it is probable that origin of a slight change in habitat preference, mean- 
ing a slight change in reaction to physical factors, a change in ecological 
optimum, is usually an early correlative of the origin of new races. 
Still the so-called taxonomic characters may remain apparently 
unchanged, while marked changes in habitat preference and in reaction 
to physical factors are being brought about in plastic animals (56). 
On the other hand, the segregation in the pure lines and races accom- 
plished in experimental breeding often appears to take place without 
any regard to environment (204). These two facts, accepted as they 
stand, are in full accord and we might conclude that there are no rela- 
tions between primary ecological characters and taxonomic characters. 
Such, however, can hardly be strictly true, but we cannot see what the 
real relations may be. If our point of view is correct the ecological 
characters of a race experimentally segregated, or experimentally pro- 
duced, must in practice consist primarily of reaction to physical factors 
or combinations of physical factors or to entire environmental complexes; 
secondly of a definite rate of metabolism, time of appearance or the like; 



ECOLOGY AND BIOLOGY 317 

thirdly of specificity of behavior, and fourthly of structural characters 
modifying behavior. Relatively fixed taxonomic integumentary charac- 
ters have no bearing on ecological matters, not even according to the 
broadest definitions of the subject. The characters which are not related 
to the environment and which are of no ecological value are the ones 
quite generally used in breeding work, specificity of behavior standing 
second, and plastic structure third, primary ecological matters usually 
receiving no adequate attention or only such attention as comes incidentally 
with the handling of the material. The results consist of noted differences 
in reaction to light of doubtful intensity and quality, or similar inaccu- 
rately measured temperature differences, etc. The testing of primary 
ecological characters can be easily conducted and will answer the question 
before us. 

With all of its imperfections and uncertainties, the ideas of phylogeny 
which are presented in our phylogenetic system of taxonomy are an impor- 
tant asset in zoological thinking from the point of view of structure and 
development. The classification which ecologists are striving to build 
up will serve a purpose in behavior, physiology, and ecology, analogous 
in this respect to that served by the phylogenetic classification in morpho- 
logical thought, but should be flexible rather than rigid and true to fact 
rather than to schemes. Figuratively speaking, an ecological classifica- 
tion cuts taxonomy vertically, showing many structural adaptations as 
matters of stratum or over-adaptations (205) or lack of adjustment to 
conditions (206, 206a). It also cuts it again horizontally, showing eco- 
logical similarity in organisms structurally and phylogenetically diverse. 
It therefore provides a new and different means of organization of data. 

In this work we have sharply separated evolution and structure, 
on the one hand, from physiology and behavior, on the other. Space, 
clearness, and the condition of the subjects have forbidden that we 
attempt to unite them here. While it may be expedient to continue in 
this manner until our knowledge of physiology and behavior is commen- 
surate with that of the other subjects, the following of such a course 
indefinitely, with respect to either morphological or physiological aspects 
of biology, cannot, if it be general, bring about the best development or 
unification of biological science. Indeed, its present lack of unity is 
traceable to such a course followed until recently by zoologists generally. 

If our understanding of the data of physiological cytology be correct, 
we may expect to find so-called structures of some sort within or among 
the cells concerned in function, which stand for or are correlated with 
each physiological state and physiological condition to which we have 



3l8 ECOLOGY 

referred. Our methods may not, at present, be sufficiently delicate to 
detect such structure, or the processes which lie back of it, but we may, 
it is believed, confidently expect the necessary methods for the detection 
of such structures and processes, and especially their correlation with and 
relation to the more permanent and more easily recognizable morpho- 
logical conditions. 

We classify the responses and changes in animals as evolution, 
modification by the environment, behavior, and physiological response. 
Are not all these, after all, but different expressions of the same or 
similar processes? Future investigations must answer this question, 
and it is around this question that the future of much that is known as 
biology hinges. 

VII. Relations of Ecology to Geography 

Ecology is primarily the study of the mores of animals and animal 
communities. It is fundamentally a branch of physiology — the physi- 
ology of the relations of animals to their environments. While we may 
study in the field and in the laboratory, both types of study are commonly 
conducted with reference to natural environments. Natural environ- 
ments are used as the basis for study, because when natural environments 
are destroyed, animals which can live in the new conditions select some 
one of several possibilities which approach the normal habitat. Habits 
appear particularly variable under these conditions. Little can be 
gained from the study of the relations of animals to man-made environ- 
ments, except in cases where the species has long been living under 
such conditions and has become fully adjusted to them. 

Ecology being a subject or branch of physiology, and including 
all of the sociological side of animal life, its relations to human geography 
are particularly intimate. Indeed, geographers have been disappointed 
with the data which zoology has furnished them, as these data are 
almost exclusively data concerning the taxonomy and morphology of 
animals. The parallelism between the geographic phenomena in animals 
and the "relation of culture to environment" lie not in the color and 
structural adaptations of animals, but in the behavior-characters of 
animals which enable them to live under a given set of conditions, and 
the behavior which those conditions produce (207, 208, 209). 

While attempting to make comparisons between human society 
and man on the one hand, and plants and animals on the other, geog- 
raphers, sociologists, and psychologists — ^in so far as I have been able 
to read their writings along this line — ^have compared structure in plants 



ECOLOGY AND GEOGRAPHY 319 

and animals with what is obviously not structure in man, namely, his 
culture and mental makeup. Waxwieler (210) compares human society 
with the whole animal kingdom, as constituting another society. McGee 
(211) takes a similar position. In discussing the relation of culture to 
environment he says: 

When the law of biotic development is extended to mankind, it appears 
to fail; for the men of the desert and shore land, mountain and plain, arctic 
and tropic, are ceaselessly occupied in strife against environmental conditions 
which transform their subhuman associates; yet men remain essentially 
unchanged, some taller, some stouter, some swifter of foot, some longer of life 
than others, yet all essentially Homo sapiens in every characteristic. 

More careful examination indicates that the failure of the law when 
extended to man is apparent only. The desert nomads retain certain common 
physical characteristics, but develop arts of obtaining water and food and these 
arts are adjusted to the local environment 

He continues with the citation of other cases. Such adjustment of 
arts (212) is comparable to the adjustment of animals with regard to 
food, nest-building, materials used in nest-building, and other features 
of ecology and behavior. Finally, animal ecology offers the material 
and methods with which many ideas of geography may be experimentally 
verified (213, 214). 



APPENDIX 

Methods or Study 

Methods used in the study of environment, while not new, involve 
the methods of several sciences. To determine the gross features, the 
methods of dynamic and historic geology and physiography, or of plant 
ecology, must be applied. For further analysis the methods of meteor- 
ology and special methods for measuring the environment physically 
and chemically must be employed, where other sciences have given us no 
data and method (see Clements). These consist of methods of studying 
the rate of evaporation, water content of the soil, and the application 
of meteorological methods to climatic details. The special chemical 
methods, aside from chemical methods of the study of the soil, consist 
of detection of the presence of excretory products in the soil or water. 
The best discussion of special methods is given in the references (35a, 43, 
69, 74, 76, 77, "7, 118, 121, 124, 125, 129, 130, 131). 

METHODS OF STUDYING ANIMALS IN THE FIELD AND LABORATORY 

a) Observation. — One important thing in ecological study is simply to 
sit quietly and watch animals, and record what they do. This requires 
much time, and the best observers often sit for hours before making the 
desired observations, but the reward is always adequate. Some good 
ecological knowledge has thus been acquired. One difficulty is encoun- 
tered in this work. When the observer is watching one animal whose 
actions are not of especial interest at that moment another animal often 
suddenly appears and does something which seems of importance or 
which is of especial interest. The observer's attention is diverted from 
its original object of observation. "Which shall I continue to watch ?" 
is often asked by the student. No definite rules can be laid down. In 
general it is probably better to follow the original object. The answer 
depends entirely upon the relative ease with which the two animals before 
the worker can be "observed. The beginner cannot answer this question 
and only experience can decide which should be followed. 

b) Experimentation. — 'Investigation in ecology requires, in prepara- 
tion, long training in both the biological and physical sciences. Persons 
not possessing such training cannot hope to make important contributions 
to the science. Ecology is a field often requiring very complicated 
experimental methods. Animal behavior and some aspects of physiology 

321 



322 ANIMAL COMMUNITIES 

are fundamental in ecology. We can sketch out here only such methods 
as are modifications of the usual method of these branches of biological 
science in such a way as to be intelligible to those somewhat familiar 
with such laboratory methods. 

(a) Experiments in the field are of prime importance in ecological 
work. Here smaller animals can be secured in numbers and subjected to 
experimental conditions before their physiological state has been modi- 
fied by bad treatment. Any student competent to undertake ecological 
investigation will find no difficulty in devising apparatus which can 
be carried into the field and which will enable him to do work of a 
high degree of scientific accuracy. Each experiment should be accom- 
panied by a control. That is, the same number of animals should be 
put under the same conditions as in the experiment, except for the one 
factor which is to be varied. For example, in an experiment designed 
to determine the reaction of animals to light, the control should be 
either equally lighted or entirely dark (more easily accomplished), and 
the experiment which is exactly the same except that the light ranges 
from darkness to bright sunlight. 

The apparatus which we have just begun to develop for this purpose 
is still in need of much perfecting. Thus far it consists of granite-iron 
and galvanized-iron containers about 13 in. long, 3 in. deep, and 4 in. 
wide. These are provided with galvanized-iron covers, somewhat larger, 
and a little deeper. One of these is provided at one end, with an adjust- 
able slide which may be used to open a slit to admit light when desired. 
In connection with this slit a mirror is provided with which the sunlight 
may be projected into the pan as nearly vertically as possible. The rays 
are allowed to pass through a water screen to cut out the heat. For work 
with temperature the same receptacles have been used and temperature 
differences secured by placing one end of the experimental tank in contact 
with hot soil and the other with cold soil. Land ahimals are confined in 
tubes II in. long by if in. in diameter with round bottom and close- 
fitting cap, shaped like the bottom. Reactions to gravitation have been 
tested with the use of wire cylinders for land animals, and glass cylinders 
lined with screen for aquatic animals. Black covers are used to exclude 
light in various ways as a check. For the study of reactions to current 
two long galvanized boxes (24X5X4 in.) have been used, one having 
screen ends and the other tight ends. They are placed in the stream 
side by side, one serving as an experiment, the other as a control. Large 
tin pans have been used in connection with the long boxes, the water in 
the experiment being stirred so as to produce a circular current, while the 



METHODS OF STUDY 323 

control is left undisturbed. The study of reactions to contact has been 
carried on by the use of pans described in connection with light and tem- 
perature and with the use of mica chips, leaves, etc. 

In all experiments the containers are divided into several divisions 
and the number of animals noted in each division counted at each 
reading. About ten readings are taken, the number being determined 
by the number of animals used, which is determined by the number that 
can be observed before they can move any considerable distance. This 
is a function of the speed of movement, which also determines the fre- 
quency of reading. Readings should be taken at such intervals as to 
enable the animals to completely adjust their positions with reference 
to the conditions in the interim. 

The most effective method of study is that of mixing animals of differ- 
ent habitats; this removes the necessity of accurate measurement for 
rough comparison. The degree of accuracy of such experiments is 
determined almost entirely by the ingenuity and care exercised by the 
experimenter. Accuracy of measurement can be acquired, but in the 
case of some factors, such as light, with some difficulty. Such accuracy 
should, how^ever, be the constant aim of the worker. 

While a high degree of accuracy may be attained in the field in the 
case of some factors and reactions, it is, in other cases, necessary to 
perform experiments in the laboratory also. As a rule all experiments 
should be performed in both field and laboratory. 

(&) To determine the most important activities: The first step in 
field observation is the continuous watching of animals throughout a 
number of life cycles. Experimentation is almost always necessary also. 
It is only under unusually favorable conditions that the relative impor- 
tance of the various periods of the life history of an animal can be 
ascertained without experimentation. On the other hand, experimen- 
tation must be correlated with field observation. Simple experimenta- 
tion on the behavior of animals in the laboratory does not illuminate 
this matter to any appreciable extent. 

To determine the habitat preference of animals, they should be placed 
in cages, in which they find several different sets of natural conditions, 
and the selection made by the animal noted. 

METHODS OF TAKING A CENSUS 

Species are of importance because each usually has a physiological 
makeup and habitat preference differing from other species. To make a 
census of the animals present in a given habitat it is necessary to visit 



324 ANIMAL COMMUNITIES 

the place at various times of day and night and at various times of the 
year, to overturn and open all loose objects. It is necessary therefore to 
collect animals which have been observed in nature in such a manner 
that the correct names can be applied later. It is customary to assign 
numbers to the animals. The method commonly used is as follows: 

Loose sheets of ruled paper are filled in with the locality, date, 
weather, etc., carbon copies usually being made as a matter of safety and 
convenience. Next, an animal, say a spider, is observed as fully as time 
permits, the observations are recorded, and the specimen, if small, is 
placed in a 4-drachm homeopathic vial containing alcohol. The notes 
are written in abbreviated form on a slip, and the same number assigned 
to the notes and to the slip which is put in the bottle. Animals too large 
to put into bottles are prepared in the same way by tying a tag to them. 
In due time the bottle is sent to a specialist who assigns the name, which 
is recorded in a blank space on the note sheet. A new sheet is filled 
out for each different habitat, and later all the sheets relating to one 
kind of a situation can be brought together. 

Nearly all animals can be sufficiently well preserved to permit 
identification by specialists, in the following manner: 

a) Vertebrates, in 10 per cent formalin, the abdomen opened to permit the fluid 

to enter. 

b) Crustaceans, most insects, spiders, worms, and lower forms by dropping into 

80 per cent alcohol. 

c) Insect larvae and pupae must be subjected to high temperature, 80° C, or 

they will turn black. Vials or bottles containing them with corks removed 
should be set in a pan of hot water for 20 minutes immediately after 
returning from the field. 

d) Flies must be killed by poison fumes, pinned in the field, and the pins set in 

suitable boxes. 

e) Moths and butterflies must be killed by fumes and pinned; the partial 

spreading of one pair of wings will suffice and save much time. 



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[References are numbered in the order of first citation in the text, beginning with 

Chapter I.] 

Chapter I 

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ga. Surface, H. A, Lizards of Pennsylvania. Ibid., V, No. 8. 1908. 

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325 



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30. Darwin, Charles. Vegetable Mould and Earthworms. London. 1892. 

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35a. Adams, Charles C. Guide to the Study of Animal Ecolog\\ New 

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Chapter IV 

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82a. Hoy, P. R. (On Dredging in Lake Michigan.) Trans. Wis. Acad., I, 
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6. Morse, A. P. Report on Orthoptera, p. 299. 

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8. Hine, J. S. Diptera, p. 308. 

9. Titus, E. S. Hymenoptera, p. 317. 

10. Wheeler, W. M. Ants, p. 325. 

11. Ruthven, A. G. Cold-blooded Vertebrates, p. 329. 

12. Peet, Max, M. Birds, pp. 97 and 337. 

84. Meek, S. E., and Hildebrand, S. F. Synoptic List of the Fishes Known 
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86. Snow, Julia W. The Plankton Algae of Lake Erie. Bull. U.S.F.C, 
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87. Jennings, H. S. The Rotatoria of the United States. Bull. U.S.F.C, 
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88. . On the Protozoa of Lake Erie. Ibid., XIX, 105. 1899. 

89. Forbes, S. A. Some Entomostraca of Lake Michigan and Adjacent 
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90. Clark, F. N. A Plan for Promoting the White Fish Production of the 
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Chapter VI 

92. Shelford, V. E. Ecological Succession. I, Stream Fishes and the 
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93. Smith, B. G. The Spawning Habits of Chrosomus erythrogaster. 
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94. Lyon, E. P. On Rheotropism. I, Rheotropism in Fishes. Am. Jour. 
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95. Needham, J. G., and others. Aquatic Insects in the Adirondacks. N.Y. 
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97. Reeves, C. D. The Breeding Habits of the Rainbow Darter. Biol. 

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98. Needham, J. G., and others. May Flies and Midges. N.Y. State Mus., 
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102. Weckel, A. L. Freshwater Amphipods of North America. Proc. U.S. 
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103. Adams, Charles C. Baseleveling and Its Faunal Significance. Am. 
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Chapter VII 

104. Juday, Chauncey. Diurnal Movement of Plankton Crustacea. Tr. 
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105. Hankinson, T. L. Walnut Lake. Biol. Surv. of Michigan (Lansing). 
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106. Gill, T. Parental Care among Freshwater Fishes. Smithsonian 
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108. Butler, A. W. Birds of Indiana. Rep. Ind. Dept. Geol. and Nat. 
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109. McGillivray, A. D. Aquatic Chrysomelidae. N.Y. State Mus. Bull., 
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no. Juday, C, and Wagner, George. Dissolved Oxygen as a Factor in the 
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111. Juday, C. Some Aquatic Invertebrates That Live under Anaerobic 
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Chapter VIII 

112. Shelford, V. E. Ecological Succession. II, Pond Fishes. Biol. Bull., 
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113. Titcomb, J. W. Aquatic Plants in Pond Culture. Rep. U.S. Bur. Fish. 
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114. Col ton, H. S. Some Effects of Environment on Growth of Lymnaea 
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114a. Dachnowski, A. The Toxic Properties of Bog Water and Bog Soil. 
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Chapter IX 

115. Shelford, V. E. Ecological Succession. IV, Vegetation and the Control 
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116. Van Hise, C. R. A Treatise on Metamorphism. U.S.G.S. Monograph, 
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117. Briggs, L. J., and McLane, J. W. The Moisture Equivalents of Soils. 
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332 ANIMAL COMMUNITIES 

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123. Congdon, E. D. Recent Studies upon the Locomotor Responses of 
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124. Zon,R., and Graves, H. S. Light in Relation to Tree Growth. U.S. 
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125. Hann, J. Hand Book of Climatology. Part I. (Tr. by R. de C. 
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126. Cohnheim, O. Physiologie des Alpinismus II. Ergebnisse der Physi- 
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127. Huntingdon, E. The Effect of Barometric Variation upon Mental 
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129. Yapp, R. H. Stratification of the Vegetation of a Marsh and Its Rela- 
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130. Livingston, B. E. The Relation of Desert Plants to Soil Moisture and 
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130C. Operation of the Porous Cup Atmometer. Plant World, XIII, 111-19, 

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131. Fuller, G. D. Evaporation and Plant Succession. Bot. Gaz., LVII, 
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131a. . Evaporation and Stratification of Vegetation. Bot. Gaz., 

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132. Greeley, A. W. On the Analogy between the Effect of Loss of Water 
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134. Shelford, Victor E. Reactions of Certain Animals to Gradients of 
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135. Shimek, B. The Prairies, Bull. Lab. Nat. Hist. State Univ. Iowa, 
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136. Sherflf, E. E. The Vegetation of Skokie Marsh. Bot. Gaz., LIV, 
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137. Felt, E. P. Insects Affecting Park and Woodland Trees. N.Y. State 
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Chapter X 

138. Emerton, J. H. Common Spiders. Boston. 1902. 

139. Dickerson, M. C. The Frog Book. New York. 1907. 

140. Hine, J. S. Habits and Life Histories of Some Flies of the Family 
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141. Woodruff, F. M. Birds of the Chicago Area. Bull. VI. N.H. Surv., 
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142. Merriam, C. H. Mammals of the Adirondack Region. New York. 
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143. Seton, E. Thompson-. Life Histories of Northern Animals. New 
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144. Pearl, R. The Movements and Reaction of Fresh Water Planarians. 
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145. Smith, J. B. Mosquitos Occurring in the State and Their Habits, Life 
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146. Marsh, C. D. A Revision of the N.A. Species of Cyclops. Trans. Wis. 
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1460. . A Revision of the N. A. Species of Diaptomus. Ibid., XV, 

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147. Sharpe, R. W. A Further Report on the Ostracoda of the United 
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148. Holmes, S. J. Description of a New Species of Branchipus from Wis- 
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149. Wolcott, R. H. A Review of the Genera of the Water Mites. Trans. 
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334 ANIMAL COMMUNITIES 

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153. Reed, C. A. Bird Guide; Birds East of the Rockies. Worcester, 
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Chapter XI 

154. Packard, A. S. Insects Injurious to Forest and Shade Trees. U.S. 
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155. Lugger, O. Beetles Injurious to Fruit-producing Plants. Bull. 66, 
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156. Blatchley, W. S. On the Coleoptera Known to Occur in Indiana. 
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157. Ditmars, R. L. The Reptile Book. New York. 1904. 

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158. Jones, F. M. Pitcher- Plant Insects. Ent. News, XV, 14. 1904. 

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162. Stone, W., and Cram, W. E. American Animals. New York. 1905, 

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Chapter XII 

164. Folsom, J. W. Insect Pests of Alfalfa and Clover. 25th Ann. Rep. 
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165. Williston, S. W. Manual of North American Diptera. New Haven. 
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166. Surface, H. A. Lampreys of Central New York. Bull. U.S.F.C, 1897, 
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167. Snow, Laetitia M. The Microcosm of the Drift Line. Am. Nat., 
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168. Needham, J. G. The Beetle Drift on Lake Michigan. Canadian Ento- 
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169. Herms, W. B. An Ecological and Experimental Study of the Sar- 
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171. Scudder, S. H. Butterflies of Eastern United States and Canada. 
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175. Shull, C, H. The Life History and Habits of Anthocharis olympia. 
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176. Hart, C. A., and Gleason, H. A. Biology of the Sand Areas of Illinois. 
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179. Howard, L. O, Insect Book. New York. 1902. - 

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181. Robertson, C. Flowers and Insects, XIX. Bot. Gaz., XXVIII, 27-45. 
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182. Richardson, H. Monograph on the Isopods of North America. Bull. 
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183. BoUman, C. H. The Myriapoda of North America. U.S. Nat. Mus., 
Bull. 46. 1893. 

184. Weed, C. M. A Descriptive Catalogue of the Phalanginae of 111. 
BulL 111. State Lab., Ill, 79-87. 1887. 

185. Wirtner, P. M. Preliminary List of the Hemiptera of Western Pennsyl- 
vania. Ann. Carnegie Mus., Ill, 133-228. 1904. 

186. Kirkaldy, G. W. Catalogue of the Hemiptera, Heteroptera. Vol. I, 
Cimicidae. Berlin. 1909. 

187. Peckham, G. W., and E. G. Sense of Sight in Spiders with Some 
Observations on Color Sense. Wis. Ac, of Sci., X, 231-61. 1895. 

188. Beutenmiiller, Wm. Insect Galls within 50 Miles of New York. Guide 
Leaflet, No. 16, Am. Mus. Nat. Hist. 1904. 

189. Forbes, S, A. 24th Report 111. State Entomologist. 1906. 

190. Washburn, F. L. Diptera of Minnesota. loth Ann. Rep. State Ent., 
Minn. 1905. 



336 ANIMAL COMMUNITIES 

191. Judd, Sylvester D. Birds of a Maryland Farm. U.S. D. Agr., Biol. 
Surv., Bull. 17. 1902. 

192. Heilprin, A. The Distribution of Animals. Appleton. 1887. 

193. Cowles, H. C. A Textbook of Botany, Part III, "Ecology." New 
York, 191 1. 

194. Hickson, S. J. On the Species of the Genus Millepora. P.Z.S. 
London, pp. 246, 257. 1898. 

195. Wood-Jones, F. Coral and Atolls. London. 1910. 

196. Woodruff, L. L. Observations on the Origin and Sequence of the Pro- 
tozoan Fauna of Hay Infusions. Jour. Exp. ZooL, XII, 205-64. 1912. 

197. Clements, F. E. Research Methods in Ecology. Lincoln, Neb. 1905. 

198. Whitford, H. N. The Vegetation of the Lamoa Forest Reserve. Philip- 
pine Jour, of Sci., I, No. 4, pp. 373-428; No. 6, pp. 437-682. 1906. 

199. Beddard, F. E. Zoogeography. Cambridge. 1895. 

200. Lydekker, A. Natural History, II and HI. Mammals. Bears no 
date. 

201. Selous, F. C. African Nature Notes and Reminiscences. London. 
1908. 

202. Ward, T. Rambles of an Australian Naturalist. 1907. 

203. Horn, W. Entomologische Reise Brief aus Ceylon. Deut. Ent. Zeit., 
228-30. 1899. 

204. Cockerel, T. D. A. Aspects of Modern Biology. Popular Science 
Monthly, December, pp. 540-48. 1908. 

205. Coulter, J. M. The Theory of Natural Selection from the Standpoint 
of Botany. Fifty Years of Darwinism, 56-71. 1908. 

206. Wallace, A. R. Malay Archipeligo. London. 1869. 

2060. Hudson, W. H. The Naturalist in La Plata. (Ed. of 1903, Dent, 
London.) 1892. 

207. Craig, Wallace. North Dakota Life; Plant, Animal and Hmnan. 
Am. Bull. Geog. Soc, XL, 321-415. Bibliography. 1908. 

208. . The Voices of Pigeons Regarded as a Means of Social Control. 

Am. Jour. Sociol., XIV, 86-100. 1908. 

209. Tarde, Gabriel. Inter-Psychology. Internat. Quar., VII, 59-84. 1903. 

210. Waxweiler, E. Equisse d'une sociologie. Inst. Solvay de Soc. Notes 
et Mem., Fasc. 2, 306, Bruxelles. 1906. 

211. McGee, W. J. The Relation of Institution to Environment. Smith- 
son. Rep., 1895, pp. 701-11. 1896. 

212. Mason, O. T, Influence of Environment upon Human Industries or 
Arts. Smithson. Rep., 1895, pp. 639-65. 1896. 

213. Tower, W. S. Scientific Geography; the Relation of Its Content to 
Its Subdivisions. Bull. Am. Geog. Soc, XLII, 801. 1910. 

214. Goode, J. Paul. Human Response to the Physical Environment. 
Jour. Geog., pp. 333-43- 1894. 



INDEXES 



INDEX OF AUTHORS AND COLLABORATORS 

Page numbers followed by figures in jiarentheses are the f>ages of the Bibliography, the parenthetical 
figures being the title numbers; the numbers following the parentheses are the pages on which the articles 
are cited by number. Page numbers occurring with no parenthesis in connection are those on which the 
authors and collaborators are referred to independently of the Bibliography. 



Abbot, C. C, 327 (53c), 34. 

Adams, C. C, 326 (35(1), 22, 32, 42, 321; 

328 (67), 48; 329 (83), 73, 79, 195; 

331 (103), 105, no, 
Alden, W. C, 328 (60, 61), 44, 46, 47. 
Aldrich, J. M., viii. 
Allee, W. C, vii, viii, 91, 92, 188; 327 

(53). 33, 91; 327 (56), 3S; 328 (73), 58. 

Atwood, W. W., 45; 328 (62), 44, 46, 210. 
Audubon, J. J., v. 

Bachmetjew, P., 333 (133), 163. 
Baker, F. C, vii, viii; 330 (91), 83, 169, 

253, 256; 330 (100), 89, 102, 189, 193, 

265. 
Baker, H. B., 335 (i8ofl), 253. 
Banks, N., vii, viii; 334 (159), 195; 335 

(172), 222, 228, 240. 
Bates, H. W., v, 275. 
Beal, F. E. L., 325 (8), 9, 10. 
Beddard, F. E., 336 (199). 
Belt, T., V. 
Bernard, Claude, v. 
Betten, C, vii; 330 (95), 93. 
Beutenmiiller, William, 265; 335 (188), 

258, 260. 
Birge, E. A., 61; 328 (74), 59, 60, 125, 

321. 
Blanchard, Rufus, 325 (15), 13. 
Blatchley, W. S., vii; 334 (156), 191, 198, 

244, 253, 255, 258, 283. 
Bohn, G., 327 (530), 34, 305. 
Bollman, C. H., 335 (183), 253. 
Brady, G. S., 130. 
Braun, M., 326 (29), 20. 
Brehan, Fabre, — 
Brehm, A. E., v; 325 (2), 5, 
Briggs, L. J., 331 (117), 157, 321; 332 

(118), 157,321. 
Browning, E. B., 3. 



Buffon, V. 

Butler, A. W., 331 (108), 130, 132, 150, 
181, 229. 

Caldwell. O. W., ix. 

Chamberlin, T. C, 328 (66), 47. 

Chaney, R., viii. 

Child, C. M., vii, ix, 108, 177-79; 326 

(37), 22, 23; 326 (37a), 23. 
Chittenden, F. H., ix, 291, 293, 295. 
Clark, F. N., 330 (90), 77. 
Class, Elva, viii. 
Clements, F. E., 336 (197), 305. 
Cockerell, T. D. A., 336 (204). 
Cohnheim, O., 332 (126), 160. 
Colton, H. S., 331 (114), 151- 
Comstock, J. H., 233. 
Congdon, E. D., 332 (123), 159. 
Cook, O. F., vii. 
Cope, E. D., 327 (39), 24. 
Coulter, J. M., ix; 336 (205), 317. 
Cowles, H. C, vi, viii, ix, i, 174, 183, 286, 

310; 328 (58), 36,42; 332 (i2oj, 159, 

305; 336 (193), 305. 309- 
Craig, W., 336 (207, 208), 314. 
Cram, W. E., 334 (162), 196. 
Cresson, E. T., viii. 
Cimningham, Clara, vii. 
Curtis, W. C, 330 (99), 99. 

Dachnowski, A., 331 (114a), 151. 

Dahl, F., V. 

Darwin, Charles, v, 24, 25; 326 (30), 20, 

159- 
DeCandolle, 161. 

Dickerson, M. C, 333 (139), 169, 195, 

234, 256, 283. 
Dimmit, B. H., vii, 278. 
Ditmars, R. L., 334 (157), 252, 255. 



339 



340 



ANIMAL COMMUNITIES 



Eigenmann, C, 327 (41), 25. 
Ellsworth, H. L., 326 (20), 14, 15. 

Emerton, J. H., ix, 229, 238; S33 (138), 
169, 220, 222, 240, 252, 257, 258, 259, 
260, 261, 263. 

Fabre, J. H., v. 

Felt, E. P., 333 (137), 166, 191, 195, 196, 
201, 225, 228, 229, 233, 257, 258, 259, 
260, 261, 266. 

Folsom, J. W., 294; 334 (164), 214, 284. 

Forbes, S. A., ix, 283, 294; 325 {5a), 9, 17; 
32s (11), 10; 326 (26), 10, 17; 329 
(79), 70, 76, 91, 92, 127. 140; 329 (85), 
7S; 330 (89), 76, 77; 335 (174), 223, 
282, 284, 285; 335 (189), 267. 

Forel, F. A., v; 329 (76), 62-64, 321. 

Fowler, H. W., 334 (157a), i94- 

Fuller, G. D., 332 (119), 158; 332 (119a), 

158; 332 (131), 162, 249, 250; 332 

(131a, 1316). 

Ganong, W. F., 327 (52), 33. 

Gerhard, W. J., vii, ix, 196. 

Giard, A., v. 

Gill, T., 331 (106), 126, 149. 

Gleason, H. A., 329 (83, 2), 79, 83; 335 

(176), 229. 
Goldthwait, J. W., 45; 328 (62, 63, 64), 

44, 46. 
Goode, J. P., ix; 336 (214), 319. 
Gorham, F. P., ix, 60. 
Graves, H. S., 332 (124), 159, 321. 
Greeley, A. W., 333 (132), 163. 

Haase, E., v. 

Haddon, A. C, 325 (4), 8. 

Hancock, J. L., vii; 327 (40), 25, 34, 181, 

190, 195, 198, 215, 218, 223, 226, 227, 

232, 23s, 241, 252, 255, 259, 260, 262, 

266, 268, 270. 
Hankinson, T. L., 331 (105), 125, 126, 

140, 151. 
Hann, J., 332 (125), 160, 161, 162, 163, 

321. 
Hart, C. A., vii; 335 (176), 229. 
Harvey, N. A., vii. 
Haswell, W. A., 326 (36), 22. 
Heilprin, A., 336 (192), 299. 
Heinemann, P. G., viii. 
Henshaw, S., viii. 



Herms, W. B., 334 (169), 219, 223. 
Herrick, C. L., ix. 
Herrick, F. H., 327 (49), 32, 34. 
Hildebrand, S. F., vii, 130; 329 (84), 73, 

78, 84. 
Hine, J. S., 329 (83, 8); 333 (140), 170. 
Holmes, S. J., 327 (536), 34, 305; 333 

(148), 177- 
Holt, W. P., 329 (83, 4). 
Hopkins, A. D., 334 (160), 195; 334 

(161), 195, 196. 
Horn, W., 336 (203), 315. 
Hortag, M., 326 (28), 20. 
Hoskins, W., viii. 

Howard, L. O., 221; 335 (179), 256, 267. 
Hoy, P. R., 329 (82a), 80. 
Huber, P., v. 

Hudson, W. H., iv; 336 (206a), 317. 
Huntingdon, E., 332 (127), 160. 

Indian Affairs, Commissioner of, 325 

(16), 13. 
Isely, F. B., 188; 330 (99a). 

Janet, C, v. 

Jennings, H. S., ix; 327 (44), 27, 34, 77, 

299. 300; 330 (87. 88), 75, 76, 77. 
Johannsen, O. A., 330 (98), 144. 
Johnstone, J., 327 (47), 31, 35, 58, 66, 68. 
Jones, A., 326 (23), 14. 
Jones, F. M., 334 (158), 193. 
Juday, C., vii, 133; 328 (74), 59, 60, 125; 

33^ (104), 125; 331 (no. III), 133. 
Judd, Sylvester D., 336 (191), 274. 

Kellogg, V. L., ix, 225, 270, 272. 
Kennicott, R., 326 (22), 14, 15, 171, 196, 

241, 289. 
Kent, W. S., 75. 

Kingsley, J. S., 326 (ss), 21; 330 (996). 
Kirkaldy, G. W., 335 (186), 257. 
Kirkland, A. H., 325 (10), 9. 
Kirkland, J., 325 (14), 13. 
Kofoid, C. A., 329 (75, app.), 74; 329 

(77), 67, 103, 125, 321. 
Kuntz, G. F., 326 (31), 21. 
Kwiat, A., vii. 

Lamarck, J. B., 24, 25. 
Lane, A. C., 455 328 (65), 44. 



INDEX OF AUTHORS 



341 



Lefevre, G., 330 (99), 99. 

Leidy, J., 75, 130. 

Leverett, F., 45; 328 (59), 44. 

Lillie, F. R., ix. 

Livingston, B. E., 332 (130, 130a, 1306, 

130c), 162. 
Loeb, J., vi; 328 (72), 58, 305. 
Lugger, O., 88, 234; ^^2, (150), 180, 191, 

273; 334 (155), 192, 201, 233; 334 

(163), 199, 202, 215. 

Lydekker, A., 336 (200). 
Lyon, E. P., 323 (94), 91, loi. 

MacGillivray, A. D., vii; 331 (109), 132. 
Marlatt, C. L., ix, 220, 265, 282; 335 

(178), 252. 
Marsh, C. D., vii; 329 (78), 67; 7,2,7, 

(146, 146a), 176. 
Marsh, M. C, 326 (24), 17; 328 (71), 58, 

59- 
Mason, E. G., 326 (19), 14. 
Mason, O. T., 336 (212), 319. 
Mast, S. O., 327 (4s), 28, 159. 
McFarland, Joseph, 326 (27a). 
McGee, W. J., 336 (211), 319. 
McLane, J. W., 331 (117), 157. 
McNutt, W., 332 (1190), 158. 
Meek, S. E., vii, ix; 329 (84) 73, 78, 84. 
Merriam, C. H., 327 (48), 32, 299; zii 

(142), 171, 189, 195, 196, 233, 238. 
Meyers, L B., 220. 

Milner, J. W., 329 (81), 73, 80, 83, 84. 
Mobius, K., V. 
Moore, B., 327 (43), 26, 321. 
Moore, J. P., vii; 330 (91a), 83. 
Morse, A. P., 329 (83, 6). 

Needham, J. G., 329 (83, 7); 330 (95), 

93, 96, 146; 330 (96), 9s; 330 (98), 99; 

334 {168), 219. 
Newman, H. H., 331 (107), 130. 
Nichols, Susan P., viii. 
Nichols, W. R., 326 (25), 17. 

Ortmann, A. E., vii; 330 (loi), 104. 
Osborn, H. F., 327 (38), 24. 
Osburn, R. C, vii. 
Osgood, W. H., viii. 

Packard, A. S., 334 (154), 191- 
Park, W. H., 326 (27), 20. 



Parker, T. J., 326 (36), 22. 

Parkman, F., 326 (18), 14. 

Pearl, R., 7,3>i (i44), 172. 

Pearse, A. S., 330 (loia). 

Peckham, G. W. and E. G., 223; 335 

(173), 222, 252, 255, 258; 335 (187), 

258. 
Peet, M. M., 329 (83, 12). 
Pettenkoffer, M., 162. 

Reed, C. A., 334 (153), 181, 189. 
Reed, H. S., 332 (121), 159. 
Reeves, C. D., 330 (97), 95. 
Reighard, J., 327 (50), 32, 90, 91, loi. 
Reynolds, John, 326 (20a), 14, 15. 
Richardson, H., 335 (182), 253. 
Richardson, R. E., 329 (79), 70, 91, 92, 

99, 127, 140. 
Riddle, O., 327 (46), 31. 
Riley, C. V., ix, 201, 234, 238. 
Ritter, W. E., 32s (i), 5. 
Robertson, C, 335 (181), 253, 255. 
Romanes, G. J., v. 
Roosevelt, T., 35; 325 (3), 5, 313. 
Ruthven, A. G., 325 (7), 9; 329 (83, 11); 

334 (152), viii, 181; 335 (180). 

Salisbury, R. D., ix; 328 (57), 36, 44, 61, 
73, 157; 328 (60), 44. 

Schimper, A. F. W., 328 (58a), 36, 38, 313, 
314- 

Schmarda, L. R., v. 

Schreiner, O., 332 (121), 159. • 

Scudder, S. H., 335 (171), 222. 

Selous, F. C., 336 (201). 

Semper, K., 327 (51), i, 2,3- 

Seton, E. T., 337, (i43), 171, i9S, 269. 

Severin, S., 10. 

Shantz, H. L., 332 (118), 157, 321. 

Sharp, D., 326 (34), 21. 

Sharpe, R. W., vii. 144; 333 (147), 177. 

Shelford, Mabel Brown, vii, 13-15. 

Shelford, V. E., 325 (6), 9, 32, 59, 68, 69, 
136, 151, 152; 325 (13), 12, 33, 311; 
327 ^55), 34, 36, 37, 38, 157, i6r, 209,. 
211, 215, 301, 302, 304, 315; 328 (73), 
58; 330 (92), 90, 99, 105, 309; 331 
(112), 136, 152; 331 (115), 157, 222, 
225, 227, 233; 7,23 (134), 163; 23Z 
(151), 211, 215, 219, 252, 256; 334 
(151a), 229; 335 (170), 219, 225, 227, 
233. 



342 



ANIMAL COMMUNITIES 



Sherff, E. E., 333 (136), 165. 

Sherman, J. D., 330 (99c), 99, 102, 104, 

105, 180, 193. 
Shimek, B., 333 (135), 164- 
Shull, C. H., 335 (i7S), 227, 257- 
Smith, B. G., 330 (93), 91. 
Smith, Fiank, vii. 
Smith, H. M., ix, 79. 
Smith, J. B., 176, 179; 333 (us), i74; 

335 (177), 252, 253, 259, 260, 261. 
Smith, S. I., ix; 329 (80), 73, 76, 78. 
Snow, JuUaW., 330(86), 75- 
Snow, Laetitia M., 334 (167), 219. 
Sparks, J., 325 (17), 13. 
Stahl, W. S., viii. 
Stanfuss, M., 327 (42), 25. 
Stephens, T. C, viii, 170, 171, i75, 228, 

229. 
Stevenson, C. H., 326 (32), 21. 
Stimpson, W., 329 (82), 73, 78, 80, 84. 
Stone, W., 334 (162), 196, 227, 
Strong, R. M., viii. 

Surface, H. A., 325 (9, 9a), 9; 334 (166), 
219. 

Tarde, G., 336 (209), 318. 
Thompson, C, 334 (152), 181. 
Thompson, H., 334 (152), 181. 
Thomson, J. A., 6. 
Titcomb, J. W., 331 ("3), Ho, 142. 
Titus, E. S., 329 (83, 9). 
Tower, W. S., 336 (213), 319. 
Transeau, E. N., 50, 51, 64; 328 (69), 

164,321; 328 (70); 332 (122), 159. 
Turner, C. H., ix. 

Van Hise, C. R., 331 ("6), 157- 
Verwom, Max, 326 (35), 22, 27, 28, 
300. 



Visher, S. S., vii, viii, 190. 
Voit, C., 162. 

Wagner, George, 331 (no), 133. 
Walker, A. C., 332 (128), 160, 299. 
Walker, Bryant, 329 (83, s), 83; 329 

(75, app.), 80, 83-85. 
Wallace, A. R., v; 336 (206), 317- 
Ward, H. B., 329 (75), 62, 64, 67, 73, 

74, 82, 83-85. 
Ward, T., 336 (202). 
Warming, E., 325 (12), 12. 
Washburn, F. L., ix, 225, 239, 290, 291; 

335 (190), 272, 285. 
Waxweiler, E., 336 (210), 319. 
Weather Bureau, 328 (68), 49. 
Webb, Sidney, 325 (5), 8. 
Weckel, A. L., vii; 331 (102), 104. 
Weed, CM., 335 (184), 253- 
Wells, M. M., vii, ix. 
Wheeler, W. M., 327 (54), 34, 252, 253, 

255; 329 (83, lo)- 
White, G., v. 

Whitford, H. N., 336 (198), 311. 
Wickham, H. F., vii. 
Wiesner, J., 160. 
Williston, S. W., 89, 217, 224, 271, 272; 

334 (165), 214, 217, 222. 
Wirtner, P. M., 335 (185), 257, 259- 
Wolcott, A. B., vu, 196; 329 (83, 3), 193- 
Wolcott, R. H., vii, 130; 333 (149), 177- 
Wood, F. E., 326 (21), viii, 14, 15, 34, 

192, 196, 255. 
Wood-Jones, F., 336 (195), 30S, 309- 
Woodruff, F. M., 333 (hO, 171, 181. 
Woodruff, L. L., 336 (196), 305, 309. 

Yapp, R. H., 332 (129), 160, 165. 

Zon, R., 332 (124), 159, 321. 



INDEX OF SUBJECTS 



Absorption of dissolved foods by aquatic 
animals, 58. 

Acclimatization, isopods, 92. 

Acorns: eaten by squirrels, 233; weevils, 
233. 

Activities: classification of, 31; dis- 
tribution and, 299-305; environment 
and, 26-30; form and, 26-27; most 
limited, 304. 

Adaptation: 24-26; of May-fly nymphs, 
96. 

African game, 7. 

Age of habitats: 44; forest, 218, 247; 
lakes, 133-34; ponds, 138, 152; 
quantity of life and, 68-69; streams, 
86, iia-14. 

Agriculture: communities of, 13, 15-17; 

near cities, 19. 
Algae: 59, 65, 70; depth limit in Lake 

Michigan, 74; filamentous, 131, 148; 

on mollusk shells, 126. 

Ammonia: in sewage, 17; in air and 
water, 59, 60; in nitrogen balance, 66; 
reactions of fishes to, 60. 

Amphibians or Amphibia, scientific 
names: 

— Acris gryllus, 135, 169, 296. 
—Amblystoma tigrinum, 149, 278, 282, 

296. 
— Bufo lentiginosus, 187, 296. 
— Chorophilus nigritus, 195, 206, 283, 296. 
— Diemictylus viridescens, 121, 149, 156. 
—Hemidadylium scutatum, 237. 
— Hyla: 

pickeringii, 194, 195, 196, 205, 207, 

234, 253. 

versicolor, 205, 234. 
— Nedurus maculosus, 130. 
— -Plethodon: 

cinereus, 197, 207, 243, 244, 256. 

glutinosus, 181, 183, 207. 
— Rana: 

caiesbeiana, 171. 

damata. 169, 171, 195. 

pipiens, 156, 169, 195, 296. 

sylvatica, 195, 206, 207, 243, 244, 256. 
Amphipods, 69, 70. 

Amphipods or Amphipoda, scientific 
names: 



— Eucrangonyx, 174: 

gracilis, 80, 85, 114, 118, 150, 154, 
185, 206. 
— Gammarus fascialus, 90, 93, 104, 114, 

118, 123, 172. 
— Hyalella knickerbockeri, 78, 104, 114, 

121, 123, 135, 144, 154. 
— Pontoporeia hoyi, 80, 81, 85. 

Anemotaxis, 161. 

Animal organism, 22-33. 

Animals: disappearance of , near Chicago, 
13-15; economic value of, 20; rela- 
tion of, to man, 5-20. 

Annelida, 103. See also Leeches. 

— Lumbriculus , 179: 
inconstans, 185. 
— Limnodrilus claparedianus , 83. 

Ant-lion, 229, 232. 

Ants: 167; aphids and, 234, 255, 290; 

swarming of, 227. 
Ants, scientific names: 
— Aphaenogaster: 

tennesseensis , 256. 

treatae, 188. 
— Camponotus, 202: 

herculeanus Ugniperdus novebora- 

censis, 207, 255. 

herculeanus pennsylvanicus , 253. 
— Dolichoderus mariae, 204. 
— Formica: 

cinerea neocinerea, 298. 

fusca, 204, 205, 207. 

fusca subsericea, 187. 

subpolita neogagates, 282, 297. 
— Lasius: 

niger americanus, 227, 252. 

umbratus mixtus aphidicola, 234, 255. 
■ — Myrmica rubra scabrinodis, 288, 297. 
— Ponera coardala, 187. ' 
Aphids: 167, 245; ants and, 234, 290; 
cherry, 223-24; consocies, 37, 214, 290; 
fecundity of, 18, 35; grain, 18; housed 
by ants, 234. 
Aphis-lions, 167, 290-91. 
Aquatic conditions: 58-67; chemical, 
58-60; food, 65-67; physical, 60-65. 
Ash: 190; galls of midrib, 192. 
Association: 37; defined, 38; listed, 39- 
41. . 



343 



344 



ANIMAL COMMUNITIES 



Atmometer, 162, 164. 

Atmosphere: 159; composition, 59; 

evaporating power, 159-62, 248-50; 

currents in, 161. 

Back-swimmers, 65,90, 117, 123, 132, 135, 

148, 151, 155. 
Bacteria: denitrification, 66; nitrifying, 

66; nitrogen-fixing, 66; number and 

age of ponds, 68; number and quantity 

of life, 66; soil, 159. 
Bacteria, scientific names: 
— Azotohacler, 66. 
— Bacterium actinopelte, 66. 
— Clostridium, 66. 
— Nitrobacter, 66. 
— Nitrococcus, 66. 
— Nitrosomonas, 66. 
Badger, 15, 167, 288. 
Balance in nature: 17-18; restored after 

the rise of a pest, 18; after disturbance 

in water, 71. 
Bark beetle: destroyer, 195; habits on 

tamarack, 195; on pine, 228. 
Bass, black: 22, 23; large-mouthed, 70, 

71, 85, 115, 120, 126, 127, 141, 156; 

rock, 85, 99, 119; small-mouthed, 85, 

99, 119, 120; warmouth, 130, 142, 

156. 
Bear, black, 14, 15, 201, 237, 245. 
Beaver, 15, loi, 199. 
Beech woods, 158, 242-52. 
Beetles, aquatic: brook, 78, 93, 96, 98, 

loi, 102, 104, 118, 121, 123; preda- 

ceous diving, 65, 90, 102, 104, 121, 131, 

135) 151 J water scavenger, 65, 104, 

131, 151, 185. 
Beetles, aquatic, scientific names: 
— Agabus, 9c : 

semipunctatus, 151. 
— A phodius fimetarius, 185. 
— Chrysomelidae, 132. 
— Coptotomus interrogalus, 135. 
— Cybister fimbriolatus, 149. 
— Dascyllidae, 179, 185. 
— Donacia, 65, 123, 135, 151. 
— Dytiscidae, 65, 102, 104, 131, 151, 185. 
— Elmis, 121 : 

fastiditus, 93, 118. 
4-notatus, 123. 
quadrinotatus , 104. 
— Haliplidae, 65. 

— Hydrophilidae, 65, 104, 131, 151, 185. 
— Hydroporus, 90: 
mellitus, 102. 
vittaius, 121. 
— Parnidae, 78, 96, 98, loi, 102. 



— Psephenus, 78, 96. 

Beetle: bark, 195, 228; boring, 191, 206, 
217, 240; click, 234, 255, 282, 297; 
ground, 167, 179, 180, 185, 186, 190, 
217, 205, 206, 272, 243; lady, 167, 
2Q3; May, 167, 290; relation to moist- 
ure, 247: snout, 223, 238, 282, 284; 
soldier, 167. 
Beetles, terrestrial, scientific names: 
— Acmaeodera pulchella, 297. 
— Acrapieryx gracilis, 277. 
— Alans: 

myops, 255. 

oculatus, 253. 
— Allopoda lutea, 207. 
— Amara: 

angustata, 296. 

polita, 204. 
— Anisdaciylus inter punctatus, 218. ■ 
— Anlhophilax attenuatus, 245. 
— Baris confinis, 204. 
— Bassareus lativittis, 258. 
— Bembidium, 185, 198: 

carinula, 179, 180, 186. 

variegalum, 186. 
— Boletobius ductus, 261. 
— Boletotherus bifurcus, 244, 261. 
— Brachybamus electus, 204. 
— Buprestidae, 191, 201. 
— Calalhus gregarius, 217. 
— Callida punctata, 276, 277. 
— Calligrapha, 267: 

multipunctata, 188, 207. 

scalaris, 241, 260. 
— Cardiophorus cardisce, 255. 
— Cerambycidae, 191, 206, 217, 240. 
— Ceruchus piceus, 253. 
— Chalepus: 

hornii, 188. 

nervosa, 207. 

scapularis, 208. 
— Chelymorpha argus, 277. 
— Chlaenius aestivus, 296. 
— Chrysochus auratus, 284, 297. 
— Cicindela: 

cuprascens, 180, 186, 219. 

formosa generosa, 225, 226, 252. 

hirticoUis, 179, 180, 186, 219, 221, 

315- 

lepida, 40, 120, 223, 252, 316. 
purpurea limbalis, 40, 210, 211, 212, 
213, 254, 302. 
re panda, 181, 186. 
saulcyi, 315. 

scutellaris lecontei, 40, 182, 227, 229, 
230, 252, 316. 

sexguttata, 41, 215, 216, 234, 254, 
256, 316. 

tranquebarica, 182. 
— Cleridae, 194. 



INDEX OF SUBJECTS 



345 



Beetles — Continued: 
— Coccinelidac, 224. 
— Coptocycla: 

bicolor, 205, 277. 

clavata, 206. 

signifera, 277. 
— Crepidodera helexinus, 108. 
— Cryptocephalus: 

cinctipennis, 297. 

venustus, 284, 297. 
— Cryptorhopalitm haemorrhoidale, 207. 
— CryptorhyncIiHS lapalhi, 267, 276. 
— Cycloneda, 293: 

sanguinea munda, 298. 
— Cyphon: 

padi, 207. 

variabilis, 207. 
— DascyUidae, 207. 
— Dedes spinosus, 277. 
— Dendrodonus simplex, 195. 
— Dermestes lardarius, 16. 
— Dcnncstidae, 207, 217, 219. 
— Desmoris scapalis, 297. 
— Diabrotica: 

i2-pundala, 187, 284, 297. 

viltata, 187. 
— Diaperis hydni, 234, 253. 
— Diplochila laticollis, 296. 
— Disonycha quinqueviUata, 224, 258. 
— Diloma quadrigtUtata, 259. 
— Donacia subtilis, 297. 
— Doryphora divicollis, 270, 277. 
— Eburia quadrigeminata, 119. 
—Elaphidion villosum, 239, 241, 277. 
— Elateridae, 234, 255. 
— Endalus limatulus, 284, 297. 
- — Epicuata, 270: 

marginata, 277. 

pennsylvanica, 277. 
— Eupsalis minuta, 201, 255. 
— Eustrophus tormentosus , 234. 
— Galeritajanus, 253. 
— Geopinus incrassatus , 220. 
— Geotrupes splendidus, 256. 
— Haltica ignita, 192. 
— Helophorus linealus, 204. 
— Hippodamia, 293: 

parenthesis, 292. 
— //(J grandicollis, 228, 258. 
— Lacon redangularis, 255. 
— Lampyridae, 205. 
— Languria: 

angustata trifasciala, 277, 255. 

gracilis, 205. 

mozardi, 293, 294. 
— Lebia atriventris, 277. 
— Limonius inlerstitiaUs , 208. 
— Z,ma, 267: 

scripta, 276. 
— Listotrophus cingtdatus, 207. 



— Listronotus: 

callosus, 204. 

inaequalipennis, 204. 
— Lixus, 293: 

tnacer, 277. 

concavus, 295. 
— Lucidota: 

atra, 188. 

pundata, 188. 
— Megalodacne heros, 247. 
— Megilla, 293: 

maculata, 292, 293. 
— Melandryidae, 206, 207. 
— Melanotus: 

communis, 256. 

fissilis, 282, 297. 
— Meracantha contrada, 253. 
— Monachus saponatus, 284, 297. 
— Mordellistena: 

aspersa, 188. 

connata, 298. 
• — Nilidulidae, 267. 
— Nodonota tristis, 188, 258, 297. 
— Oberea tripnndata, 277. 
— Odontota nervosa, 260, 297. 
— Orthosoma brunneum, 239, 253. 
— Pachybrachys, 293, 298: 

abdominalis, 188. 
— Pachyscelus laevigatus, 188. 
— Parandra brunnea, 190. 
— Passalus cornutus, 239, 240, 242, 247. 
— Pelidnota punctata, 208, 277. 
— Penlhe pimelia, 247. 
— Phloeotrya quadrimaculata, 207. 
— Photinus: 

corruscus, 207. 

pundulatus, 298. 
— Pissodes strobi, 196. 
— Platynus. 192: 

affinis, 296. 

decens, 205. 

picipennis, 204. 
— Pledrodera scalator, 225, 258. 
— Podabrus: 

basilaris, 261. 

rugulosus, 208. 
— Polygraphus rufipennis, 194, 195, 206. 
—Prionus, 233, 239. 
— Psyllobora 20-maculata, 207. 
— Pterocyclon mali, 246. 
— Pterostichus: 

adoxus, 206, 207, 243. 

cor acinus, 206. 

lucublandus, 205. 

pennsylvanicus , 206. 

5a>'?, 255. 
— Ptilinus ruficornis, 245. 
— Ptilodadyla serricollis, 188. 
— Pyractomena borealis, 188. 
— Pyrochroidae, 191, 201, 247. 



346 



ANIMAL COMMUNITIES 



Beetles — Continued: 

— Rhinoncus pyrrhopus, 208. 

— Saperda: 

concolor, 267, 276. 

lateralis, 276. 
— Saprinus patruelis, 186, 219. 
— Scarabaeidae, 207, 286. 
— Silpha surinamensis, 253. 
— Sphenophorus, 223: 

pertinax, 284. 
— Siaphylinus violaceus, 256. 
— Stereopalpus: 

hadiipennis, 219. 

mellyi, 188. 
— Slrangalia acuminata, 208. 
— Synchroa punctata, 206. 
— Tachinus pallipes, 260. 
— Telephorus lineola, 204. 
— Tenebrionidae, 201, 217. 
— Tetraopes tetraophthalmus , 270, 297. 
— Thanasimiis dubius, 194, 195, 206. 
— Tharops ruficornis, 247, 
— Tomicus. See Ips. 
— Trirhabda tormentosa canadensis, 276, 

293, 297. 
— Tritoma unicolor, 244. 
— Typophorus: 

canellus, 282, 284. 

canellus aterrimus, 188, 297. 

canellus gilvipes, 298. 

canellus sellatus, 188. 
— Uloma impressa, 255. 
— Xanthoma lo-notata, 241, 260. 
— Xylopinus saperdioides , 256. 
Behavior rhythms, related to tide, 34. 
Bionomics, 32. 
Biota, defined, 34. 

Birds: economic value of, 8-1 1; protec- 
tion of, 8-1 1, 57; feeding grounds of 
aquatic, 130, 132. 
Birds, scientific names: 
— Ardetta exilis , 171. 
— Empidonax trailli, 190. 
— Gallinula galeata, 171. 
— Tyrannus tyrannus, 228. 
— Xanthocephalus xanthocephalus, 170. 
Bison, 14, 201, 283, 289. 
Bittern: American, 171; least, 171. 
Blackbird, red-wing, 171, 174, 175; 

yellow-head, 170, 171. 
Black fly, 87-89, 93, 95, 105, 114, 116, 

118. 
Blowouts, 229. 
Blue racer, 227. 
Bluebird, 242. 
Bluejay, 242, 244. 



Bobolink, 9, 167, 283, 289. 

Bobwhite, 269, 275. 

Borers: buprestid, 191; cerambycid, 
191; of trees, 191; four marked, 191; 
common to swamp forest trees, 191. 

Bottom: communities of, in Lake 
Michigan, 77-80; distribution on, 
107, 108; factor, 43; gravel, 91; 
important, 64; in deep water, 80; lake, 
125; pond, 140, 141; stony, 95; 
stream, 86. 

Braconids, 290. 

Breeding: of aquatic insects, 65; of birds 
{see common names of); of brook 
fishes, 90-91; of lake fishes, 126; of 
mammals {see common names of); of 
mites, 129; of musk turtle, 130; of 
pond fishes, 141. 

Bronzed grackle, 275. 

Brook trout, 31. 

Brook-mores of sowbug, 90. 

Brown thrasher, 268, 275. 

Buffalo fish, 130. 

Bullhead: 70; speckled, 126, 141, 156; 
black, 102, 119, 120, 149, 156; yellow, 
156. 

Bumblebee, 190. 

Bunting: indigo, 268, 274, 275; lark, 289. 

Buttonbush, 190. 

Cabbage butterfly, 221, 222, 227. 

Caddis-flies, 65. 

Caddis- worms: caseless, 88, 116; case- 
weighting, 125, 126, 135, 140, 143, 
155; leaf-tube making, 39, 105, 114, 
121, 146, 148, 155, 174, 185; mores of, 
126; sand-tube making, 39, 142, 143, 
148, 155; sandy bottom, 135; spiral- 
cased, 96, 99, 117, 121; stick-using, 

lOI. 

Caddis- worms, scientific names: 

— Chimarrha sp., 116. 

—Goera, 125, 135, 140, 142, 143, 155. 

— Helicopsyche, 96, 99, 117, 121. 

—Hydropsyche, 39, 79. 93, 94, 95, 96, 

105, 107, 118, 121, 123. 
— Leptoceridae, 143, 148, 39, 155, 442. 
— Limnophilidae, 117. 
— Molanna, 125, 134. 
— Neuronia, 39, 148, 155, 185. 
— Phryganeidae, 105, 114, 121, 146, 148, 

174. 
— Polycentropidae, 135. 
— Rhyacophila, 88. 
— Rhyacophilidae, 88. 



INDEX OF SUBJECTS 



347 



Calumet beach, 46. 

Carbon dioxide: important to animals, 
59, 60; in air, 59; in ponds, 68; in 
sewage, 17; in springs, 93; in streams, 
86; relation to quantity, 66-70. 

Carp, 31, 120, 130. 

Carrion: 219; feeder, 219. 

Catbird, 268, 275. 

Caterpillar: achemon sphinx, 232; 
American dagger-moth, 192; cecropia, 
198, 199; common to marsh forest 
trees, 192; forest tent, 192; hickory 
tussock-moth, 192; maia moth, 268; 
prominent, 232, 233; puss, 232; slug, 
233; smeared dagger-moth, 192; vice- 
roy, 198, 199; white-marked tussock- 
moth, 192. 

Catfish, lake, 85. See Bullhead. 

Cecidomyiidae, 215, 229. 

Center of distribution, 303. 

Chara, bottoms covered with, 140, 141, 
142, 145; communities, 140-45; not 
good animal food, 142. 

Characters of communities of forest, 250, 
251. 

Chicago region: climate, former, 47, 
present, 49; extent, 48; guide to, 50; 
topography, 48; vegetation, 49. 

Chickadee, black-capped, 229. 

Chipmunk, 34, 196, 269, 274. 

Chordata, 2. 

Chub: creek (Sec Horned dace); river, 
119. 

Cicada: 227; nymphs, 262, 268. 
Circulation of water: lake, 60, 61; 

pond, 136; stream, 60. 
Cladocerans, 76, 83, 134, 173. 

Cladocerans or Cladocera, scientific 

names: 
— Acropcriis harpae, 134. 
— Bosmina, 76: 

obtnsirostris, 134. 
— Ceriodaphnia, 134, 152: 

pidchella, 152. 

quadrangiila, 152. 

reticulata, 134. 
— Chydorus sphaerlcus, 134. 
— Daphne: 

hyalina, 76, 83. 

retrocurva, 76. 
— Daphnia. See Daphne. 
— Daphnidae, 278. 
— Diaphanosoma brachynrum, 134. 
— Leptodora hyalina, 76. 
— Macrolhrix rosea, 134. 



— Pleuroxus denticulatiis, 134. 
— Polyphemus pediculus, 134. 
— Scapholcberis miicronata, 134. 
— Simocephalus serrtilatus, 134. 

Classification: ecological, 2; taxonom- 
ic, 2. 

Climate: 49; former, 47. 

Chmatic communities, 38-41, 42, 49, 
50, 310-15. 

Coloration, 25. 

Combinations of factors, 161-66. 

Communities: basis, 33, 34; behavior 
in, 27; classification, 37-41; conver- 
gence, 309-12; decline of primeval, 
13-16; defined, 3; man-made, 12-18; 
mapped, ii; of buildings, 16; of culti- 
vated lands, 16; of forest, 189-261; 
of forest border region, 39-41; of 
forest margins, 262-77; of large lakes, 
73-85; of marshes, 169-80; of orchards, 
16; of ponds, 136-56; of prairies, 287- 
98; of roadsides, 12, 16, 275, 276; of 
small lakes, 125-35; of springs, 93; 
of streams, 86-123; of thickets, 262- 
77; relations of animals in, 35, 70-71, 
166-68. 

Conditions of existence: aquatic, 58-72; 
terrestrial, 157-67. 

Consocies: aphid, 37, 214, 234, 290; 
beech log, 245-47; defined, 37; log, 
150-51; pitcher-plant, 40, 193; pool, 
39, 90; spring, 39, 93; temporary rapids, 
39, 87, 88. 
Convergence of communities: 309-12; 

of habitats, 93, 94. 
Coot, 170. 
Copepods: fecundity of, 35; in young 

ponds, 173. 
Copepods, scientific names : 
—Canthocamptus northumbricus, 206. 
— Cyclops, 278: 

albidus, 134, 152, 206. 
bicuspidatus, 76, 83. 
leuckarti, 83. 
prasinus, 83. 
serrulatus, 134, 206. 
viridis, 152. 

viridis americanus, 1 76, 206. 
viridis brevispinosus, 134. 
— Diaptomus, 179, 278, 279: 
ashlandi, 83. 
leptopus, 152. 
oregonensis, 83. 
reighardi, 135, 152. 
stagnalis, 176, 179, 185. 
— Epischura lacustris, 83. 



348 



ANIMAL COMMUNITIES 



Correspondence of communities, 313-15. 

Cowbird, 274, 275, 290. 

Coyote, IS, 167, 286. 

Crane-fly: larvae, 190; adults, 191. 

Crappie, 115, 120, 126, 140. 

Crayfish: 69, 70, 199; behavior in 

drought, 90. 
Crayfish, scientific names: 
— Cambarus: 

blandingi acutus, 114, 116, 154. 

diogenes, 114, 121, 199, 204, 296. 

gracilis, 296. 

immunis, 144, 154. 

propinquus, 85, 90, 104, 114, 116, 

118, 121, 123. 

virilis, 85, 90, 105, 114, 116, 121, 

126, 135. 
Creeks, sluggish, 102. 
Cricket, striped shrub, 266. 
Crickets, 167. 
Crossbill, 229. 
Crow, 242. 

Crustaceans or Crustacea: 67; as food, 
20; pelagic, 76; deep-water, 80. See 
Entomostraca, Crayfish, Sowbugs, Am- 
phipods. Shrimps, and Mysis. 
Current: water, 43, 61, 73, 86: about 
stones, 61; intermittent, 90; swift, 
94-99; reactions to, 29, 34, 91, 
Cutworms, hibernating, 201. 

Dace: black-nosed, 91, 92, 106, in, 115; 

horned, 90, 91, 106, in, 115, 119, 120; 

red-bellied, 91, in, 115, 119. 
Damsel-flies, scientific names: 
— Argia, 121: 

putrida, 116. 
— Calopteryx maculata, 99, 105, 116, 118. 
— Enallagma, 117, 135, 155, 185. 
— Ischnura verticalis, 104, 123, 132, 135, 

155- 
— Lestes, 155. 

Damsel-fly nymphs, 99, 104, 105. 116, 
117, 118, 121, 123, 130, 132, 135, 155, 
185. 

Darter: 34, 97; banded, 95, 97, 119, 
120; black-sided, 95, 97, 120; Johnny, 
84, 91, 95, 105, 115, 119, 120, 126, 13s; 
least, 84, 119; rainbow, 95, 97, 119, 
120. 

Day and night, responses associated 
with, 30. 

Deep-water communities of Lake Michi- 
gan, 80. 

Deer, 14, 201, 238, 245, 269. 



Desmids, 76. 
Diatoms, 76. 
Dickcissel, 167, 283, 289. 
Digger-wasps, habits of, 222, 231. 
Dip-nets, illegal, 57. 
Disagreement of communities, 307-8. 
Dissolved foods of aquatic animals, 58. 
Diurnal depth migration of Enlomostraca 

and rotifers, 77. 
Dogfish, 156. 
Dormancy: of eggs, 177-80; of winter 

bodies, 129. 
Dragon-flies, adult, food habits, 227. 
Dragon- flies, scientific names: 
— Aeschna, 118: 

constricta, go, 114. 
— Aeschnidae, 104, 117. 
— Anax, 142: 

Junius, 132, 135, 155. 
— Basiaeschna Janata, 121, 
— Celithemis eponina, 155. 
— Cordulegaster obliquus, 90, 114. 
— Epiaeschna heros, 155. 
— Gomphus: 

exilis, 99, 116, 121. 

spicatus, 143, 155. 
— Leucorhinia, 142; 

intacta, 146, 147, 155. 
— Libellula pulchella, 155. 
— Libellulidae, 104. 
— Macromia taeniolata, 103, 123. 
— Pachydiplax longipennis, 155. 
— Plathemis lydia, 116. 
— Tetragoneuria cynosura, 114, 135. 
— Tramea, 142: 

lacerata, 155. 
— Sympetrum, 155: 

rubicundulum, 155. 
Dragon-fly nymphs, 90, 93, 99, 103, 104, 
116, 117, 118, 121, 123, 132, 135, 142, 
143, 146, 147, 155. 
Drift, animal, 219. 

Droughts: 90; behavior of stream 
animals in, 92, 105; force animals 
downstream, 106. 
Duck, wood, 181, 190, 191. 
Dunes, moving, 229. 

Earthworms, 20, 190, 262, 269. 
Ecological agreement: of communities, 

305; of individuals, plants, and animals, 

304-8; of species, 315. 
Ecological equivalence, 34. 
Ecology: content of, 32, 299-318; 

genetic, 113, 137, 247-52, 308-15; 



INDEX OF SUBJECTS 



349 



Ecology — Continued: 
organization of, 23, 25, 7,2, 2,Z', physio- 
logical, 299-308; relation to biology, 
315-18; relation to geography, 318-20; 
relation to sociology, 318. 

Economic problems: 9-1 1; preservation 
of breeding, grounds of fishes, 1 26. 

Eel, 84. 

Egg-laying, of aquatic insects, 107, 108. 

Electricity, 161. 

Elk, 14, 201, 269. 

Elm: American, 190; coxcomb gall of, 
192. 

England: bird protection in, 8; man- 
made nature in, 11. 

Entomostraca, 20, 69, 70, 71, 76, 133, 152, 
176, 179, 204; {see Cladocerans, 
Copepods, and Ostracods); the food 
of young fishes, 76. 

Environment: 42-56, 58-67, 157-66; 
299; factor of, 42-44; relation to, 
22-33. 

Equihbration : of aquatic communities, 
diagram illustrating, 70; of land 
communities, 166-69; diagram illus- 
trating, 167. 

Erosion, important on clay bluffs, 209, 
210. 

Ethology, 32. 

Evaporation: 162-65; effect upon 
animals, 162-63; expression of con- 
ditions, 162; of different habitats, 
164; in forest stages, 248-49; reactions 
to, and death by, 163. 

Evaporimeter: Piche, 164; porous cup, 
162. 

Factors in distribution, 299, 
Fairy shrimp, 177-79, 185, 278-79. 
Field study: legal aspects, 56; methods, 

321-24. 
Fish: breeding of, 126; destroyed by 
lampreys, 219; feeding, 130; longi- 
tudinal distribution in streams, 109, 
no, 115, 119, 120; protection, 56,57; 
traps, 80. 
Fish, scientific names: 
— Abramis, 65: 

crysoleucas, 102, 115, 119, 120, 142, 
143, 156. 
— Acipenser rubicundus, 85. 
— Ambloplites rupestris, 85, 99, 119. 
— Ameiurus: 
lacustris, 85. 
melas, 102, 119, 120, 149, 156. 



naialis, 156. 

nebulosus, 156. 
— Amia calva, 156. 
— Anguilla rostrata, 84. 
— Aphredoderus say anus, 120. 
— Aplodinotus grunniens, 85. 
— A rgyrosomus: 

artedi, 82, 84. 

hoyi, 81, 82, 85. 

nigripinnis, 81, 82. 

prognathus, 79, 80, 82, 85. 
— Boleosoma nigrum, 84, 91, 95, 105, 115, 

119, 120, 135, 
— Campostoma anomalum, 119, 120. 
— Carpiodes, 85. 
— Catostomus: 

catostomus, 84. 

commersonii, 84, gi, 92, 106, 115, 

119, 120. 

nigricans, 84, 119. 
— Chaenobryttus gulosus, 142, 156. 
— Chrosomus erythrogaster, 91, in, 115, 

119. 
— Coregonus clupeiformis, 82, 85. 
— Cristivomer namaycush, 79, 82, 85. 
— Cyprinus carpio, 120. 
— Eriniyzon sucetta, 115, 119, 142, 156. 
— Esox: 

lucius, 85, 115, 120, 140. 

vermiculatus , 105, 115, 142, 156. 
— Etheostoma: 

coeruleum, 95, 97, 119. 

flabellare, 95, 97, 119. 

zonale, 95, 97, 119, 120. 
— Eucalia inconstans, 85. 
— Eupomotis gibbosus, 84, 156. 
— Fundulus: 

diaphanus menona, 84, 123. 

dispar, 120, 132, 135. 

notaius, 119. 
— Hadropierus aspro, 95, 97, 120. 
— Hiodon: 

alosoides, 85. 

tergisus, 85. 
— Hybopsis kentuckiensis, 119. 
— Labidesthes sicculus, 85, 130, 135. 
— Lepisosteus osseus, 85. 
— Lepomis: 

cyanellus, 102, 119, 120, 128, 156. 

megalotis, 99, 119. 

pallidum, 84, 99, 115, 119, 120, 156. 
— Lota maculosa, 82, 85. 
— Microperca punclulata, 84, 119. 
— Micropterus: 

dolomieu, 85, 99, 119, 120. 

salmoides, 85, 115, 120, 128, 156, 
— Moxostoma: 

aureolum, 84, 115, 119, 140. 

breviceps, 120. 



350 



ANIMAL COMMUNITIES 



Fish — Continued: 
— Notropis: 

atherinoides, 84. 

blennius, 84, 119, 127, 135. 

cayuga, 115, hQj i40- 

cornutus, 115, "Q. 120, 140. 

hudsonius, 84. 

rubrifrons, 119. 

timbratilis, 119, 120. 
— Noturus flavtis, 119. 
—Perca flavescens, 85, 99, 119, 120, 126, 

156. 
— Percopsis giiUatus, 84. 
— Phenacobius mirabilis, 119. 
— Pimephales: 

notatus, 84, 91, 115, 119, 120. 

promelas, 115. 
— Potnoxis: 

annularis, 115, 140- 

spar aides, 120. 
— Rhinichthys atronasus, 91. 93, 106, iii, 

IIS- 
— Schilbeodes: 

exilis, 95. 

gyrinus, 85, 105, 119, 142- 
— Semotilus airomaculatus, 91, 106, iii, 

115, 119, 120. 
— Slizostedion vitreum, S5. 
— Triglopsis thompsoni, 81. 
— Umbra, 65 : 

/mj, 84, 119, 120, 142, 143. 149. 150. 

Fisher, 196. , , 

Flatworms: brown cigar-shaped, 174; 
green, 176, 179; vernal planarians, 176. 
Flatworms, scientific names: 
— Dendrocoelnm, 118, 172. 
— Mesostoma, 174, i8S- 
— Planaria: 

dorotocephala, 118, 172. 

maculata, 135. 

velata, 176, 185, 278. 
— Vortex, 176, 179: 

viridis, 185, 278. 
Flesh-flies, 119. 
Flicker, 274, 275. 
FUes, or diptera, scientific names: 
— Anthomyidae, 284. 
— Asilus, 285. 

— Bibio albipennis, 266, 268. 
— Bombylius major, 232. 
— Cecidomyia: 

verrucicola, 192. 

viticola, 191. 

vitis-pomum, 191. 
—Chlorops sulphurea, 284. 
— Chrysomyia macellaria, 186. 
— Chrysops: 

aesttians, 188. 

callidus, 188. 



— Coenomyia ferruginea, 271, 277. 

— Coenosia spinosa, 285. 

— Cynomyia cadaverina, 186. 

— Dasyllis, 270. 

— Dolichopodidae, 284, 297. 

— Drosophila amoena, 207. 

— Drosophllidae, 284. 

— £mx, 224. 

— Eristalis tenax, 214, 270, 272, 293, 297, 

298. 
— Exoprospa, 223, 224. 
— Helobria hybrida , 272, 277. 
— Helophihis conostoma, 285. 
— Loxocera pectoralis, 208. 
— Mesogramma, 292. 
geminata, 297. 
marginata, 188, 205. 
polita, 292. 
— Milesia virginiensis, 259 271, 272. 
— Muscidae, 219. 
— Mycetophilidae, 217, 247. 
— Osinidae, 284. 

— Pachyrhina ferruginea, 256, 277, 285. 
— Paragus anguslifrons , 285. 
— Pipunculus fuscus, 280. 
— Promachus vertebratus, 222, 224. 
— Psilidae, 208. 
— Psilopodimcs sipho, 270. 
— Sapromyza philadelphica, 239, 257. 
— Sarcophaga, 186. 
— Sarcophagidae, 219. 
— Sciara, 217. 
— Sciomyzidae, 204, 284. 
— Scoliocentra, 279: 

helvola, 280. 
— Sepedon pusillus, 204. 
— Sparnopolius flavius, 285. 
— Spilogaster, 281. 
— Spilomvia longicornis, 261. 
— Spogos'tyhim anale, 229, 230, 234, 252. 
— Slraussia longipennis, 40, 272, 277. 
— Syritta pipiens, 285. 
— Syrphus: 

americanus, 202. 
ribesii, 214. 
— Tabanidae, 170. 
— Tabanus lineola, 281. 
— Tctanocera, 170, 188, 279: 
combinata, 188. 
plumosa, 188, 197, 284. 
saralogensis, 188. 
umbrarum, 188, 280, 284, 297. 
— Tipulidae, 206. 
—Tritoxa flexa, 285, 297. 
Flood-plain communities, 197-204. 
Floods: 105; insects in, 203; inammals 
in, 202; mixing of communities by, 
105; upstream migration during, 106, 
107. 



INDEX OF SUBJECTS 



3SI 



Fly larvae, scientific names: 

— Ceratopogon, 148, 155. 

— Chironomidae, 103, 187, 191. 

— Chironomus, 93, 96, 99, 116, 117, 118, 
123, 134, 142. 

— Corel hra, 125. 

— Dixa, 93, 118. 

— Metriocnemis, 83, 84. 

— Pedicia albivitta, 114. 

— Simulinm, 87, 88, 93, 105, 114, 116, 118. 

— Slratiomyia, 123. 

— Tabanus, 116. 

—Tanypus, 93, 118, 148, 155. 

Flycatcher: Traill's, 190; great crested, 
196, 244. 

Food: factor in distribution, 299; 
emphasized by paleontologists, 299; of 
young fishes, 76, 142, 144; relations: 
aquatic, 65-72, terrestrial, 166-68. 

Forest communities: 189-261; clay, 210- 
17; dry, 209-33; flood-plain, 197-203; 
mesophytic, 233-47; rock, 217-18; 
swamp, 189-93; sand, 218-33; sum- 
mary of, 250-51; tamarack, 193-97; 
wet, 189-200. 

Forest margin communities, 262-75. 

Form, relation to function, 22. 

Formations, defined, 38. See Communi- 
ties. 

Fox: gray, 15, 237, 245; red, 201, 236, 
237, 245- 

France: bird protection in, 11; Phyl- 
loxera in, 191. 

Frog: 173; bull, 171; common, 156, 169, 
195, 296; cricket, 135, 169, 296; green, 
169, 171, 195; swamp tree, 195, 206, 
283, 296; tree, 205, 234; tree (Picker- 
ing's), 194, 19s, 196, 207, 234, 244, 
253; wood, 195, 206, 207, 243, 244. 

Function, relation to form, 22. 

Gall flies, 40, 191, 272, 277. 

Gallinule, Florida, 171. 

Gar, long-nosed, 85. 

Garter-snake, 167. 

Gas-bubble disease of fishes, 60. 

Geology, surface in young stream, 8. 

Gland, silk, 95. 

Glen wood beach, 46. 

Goldfinch, 268, 274; American, 199, 274. 

Gopher, pocket, 167, 288. 

Gorditis, loi. 

Grape: apple gaU of, 191; free from 

Phylloxera in wet soil, 190; tube gall 

of, 191; wart gall of, 191. 



Grasshoppers: 167, long-horned, 227; 

maritime, 223-25. 
Grebe, pied-billed, 132. 
Green snake, 289. 
Grossbeak, pine, 229. 
Ground beetles, 180. 
Grouse, ruffed, 196, 227. 
Guide to Chicago region, 50. 

Habitat: preference, 31; selection, 34. 
Hair-worm (Gordius), 10 1. 
Hare, varying, 15, 191, 195. 

Harvestmen, scientific names: 
— Liobunum: 

dorsatum, 202, 205, 208. 

grande, 204, 298. 

nigropalpi, 244, 253. 

ventricosum, 202, 208. 
— Oligolophus pictus, 244, 261. 
Hawk: marsh, 167; night, 167, 289; red- 
shouldered, 242; red-tailed, 242; sharp- 
shinned, 274, 275; sparrow, 274, 275. 
Hemiptera (true bugs), aquatic, scientific 

names : 
— Belostoma, 65, 131. 

americana, 148. 
— Belostomidae, 65, 151. 
— Benacus, 131. 

griseus, 148. 
— Buenoa, 132: 

plalycnetnis , 135, 148, 155. 
-—Corixa, 104, 117, 123, 155. 
— Notonecta, 117, 132: 

undulata, 135, 148, 155. 

variabilis, 123, 135, 148, 155. 
— Notonectidae, 151. 
— Pelocoris femoratus, 104, 123. 
— Plea, 132: 

striola, 148, 155. 
— Ranatra, 65, 131, 151. 

fusca, 104, 123, 155. 

kirkaldyi, 155. 
— Zaitha, 65. 

fluminea, 104, 116, 123, 135, 148, 155, 

185. 
Hemiptera, terrestrial, scientific names: 
— Acanthocephala terminalis, 241, 257. 
— Acholla multispinosa, 199, 208. 
— Adelphocoris rapidus, 188, 214, 264, 

266, 276, 292, 297. 
— Agallia 4-punctata, 298. 
— Alydus conspersus, 292, 297. 
— Amphiscepa bivittata, 188, 199, 208, 

292. 
— Aphrophora, 202: 

4-notata, 267. 



352 



ANIMAL COMMUNITIES 



Hemiptera — Continued: 
— Athysanus: 

siriolus, 297, 298. 

parallelus, 297. 
— Banasa calva, 261. 
— Campylenchia curvata, 292, 297. 
— Cercopidae, 204, 261. 
— Ceresa: 

borealis, 206. 

bubalus, 26s, 276, 284, 292. 
— Ckariesterus antennator, 259. 
— Chlorotettix: 

spatulata, 298. 

tergata, 297. 

unicolor, 297. 
— Cicada Hnnei, 260. 
— Cicadula: 

6-notata, 283, 297. 

variata, 206. 
— Clastopiera: 

obtusa, 261. 

proteus, 277. 
— Colopha ulmicola, 192. 
— Corynocoris distinctus, 276. 
— Corythuca arcuata, 233. 
— Cosmopepla carnifex, 187, 188, 298. 
— Cymus angustatus, 188. 
— Diedrocephala coccinea, 277. 
— Diplodus luridus, 228. 
— Draecidacephala moUipes, 188, 283, 297. 
— Empoasca ntali, 188, 298. 
— Enchenopa binotata, 274. 
— Euschistus: 

fissilis, 264, 276. 

tristigimus, 205, 241, 260, 264. 

variolarius, 259, 298, 306. 
— EuteUix straminea, 298. 
— Garganus fusiformis, 298. 
— Gargaphia tiliae, 244, 261. 
— Gelastocoris oculatus, 180, 185, 186. 
— Gypona: 

octolineata, 206, 261. 

striata, 206. 
— Halticus uhleri, 292, 298. 
— Helochara communis, 297. 
— Horcias: 

goniphorus, 292. 

marginalis, 298. 
— Hyaiiodes vitripennis, 41, 234, 235, 260. 
— Idiocerus snowi, 208. 
— Ilnacora stalii, 277. 
— Ischnodemus falicus, 188. 
— Jassus olitarius, 261. 
— Lepyronia quadrangularis, 204, 208. 
— Lygus: 

plagiatus, 206. 

pratensis, 198, 208, 257, 263, 266, 
292, 306. 
— Macrosiphum granaria, 290. 
— Megamelus marginatus, 277. 



— Mm5 dolobrata, 292, 297. 

— Neides muticus, 263, 276. 

— Neuroctenus simplex, 231, 269. 

— Nezara hilaris, 199, 208, 257. 

— Ormenis pruinosa, igi. 

— Otiocerus degeeri, 259. 

— Parabolocratus viridis, 188. 

— Pelogonus americanus, 204. 

— Pemphigus: 

imbricator, 244, 245. 

populicaulis, 225, 258. 

vagabundus, 225, 258. 
— Pentagramma vittatifrons, 204. 
— Pentatomidae, 261. 
— Philaronia bilineata, 187. 
— Phlepsius irroratus, 259. 
— Phylloxera, 190, 243, 273: 

caryae-caulis, 260. 

vastrairix, 191, 273. 
— Phymata erosa fasciata, 187, 264, 276, 

293, 297. 
— Physatochila plexa, 188. 
— Plagiognalhus: 

fuscosus, 208. 

politus, 298. 
— Platymetopius acutus, 298. 
— Podisus maculiventris, 257, 277. 
— Poecilocapsus lineatus, 206, 270, 272, 

276, 277. 
— Protenor belfragei, 276. 
— Reduviolus: 

annulatus, 208, 260, 202, 239. 

/en/j, 187, 283. 

subcoleoptratus , 217. 
— Salda: 

coriacea, 296. 

humilis, 180. 
— Saldidae, 180, 219. 
— Scaphoideus: 

auronitens,. 239, 260. 

immistus, 206. 
— Schizoneura, 273. 
— Scolops sulcipes, 263, 265, 276. 
— Stictocephala lutea, 297. 
— Stiphrosoma stygica, 276. 
— Telemona querci (monticola), 259, 233, 

— Teratocons discolor, 297. 
— Thyreocoris: 

pulicaria, 298. 

unicolor, 187. 
— Thyreocoris unicolor, 187. 
— Trigonotylus ruficornis, 298. 
— Triphleps insidiosus, 259, 306. 
— Typhlocyba querci btfasciata, 233, 259. 
Heron, green, 181, 192. 
Herring: lake, 82, 84; toothed, 85. 
Hibernation groups: of beetles, 192-93; 
of snails, 192; of flood-plain animals, 



INDEX OF SUBJECTS 



353 



History: of Chicago region, 13-15; 

geological, 45-48. 
Hog-nosed snake, 231. 
Hornet, white-faced, hibernation of, 192, 
Homtails, 217. 
Humus in soil, 158. 
Hydra, 107, 131. 
Hymenoptera: scientific names: 
— Agapostemon: 

splendcns, 232, 259. 

virididus, 297. 
— Atnmophila, 231: . 

nigricans, 285. 

procera, 231. 
— Andrenidae, 224, 255. 
— Andricus seminator, 234, 260. 
— Anomoglossus pusillus, 188. 
— Anoplius: 

divisus, 222, 252. 

marginatits, 255. 
— Apidae, 224. 
— Apis mellifera, 214. 
— Augochlora: 

conjiisa, 187, 252. 

pura, 239, 256. 
— Bembex spinolae, 222, 223, 252. 
— Bombus: 

americanorum, 214. 

separaius, 290, 297. 
— Ceropalidae, 255. 
— Chloralictus cressoni, 277. 
— Cimbex americana, 208, 267. 
— Coeloixys rufitarsus, 231, 255. 
— Crabro interruptidus , 277. 
— Dielis pliimipes, 222, 252. 
— Epeolus: 

cressonii, 285. 

pusillus, 231, 253. 
— Eumenes fraternus , 266, 276. 
— Eumenidae, 255. 
— Halictus nelumbonis, 255. 
— Ichneumon: 

extrematatus , 192. 

galenus, 192, 297. 

mendax, igi, 192. 

zebratus, 285. 
— Ichneumonidae, 261. 
— Larridae, 255. 
— Microbembex, 223: 

monodonta, 222, 223, 252. 
— Mutilla ornativentris, 222, 252. 
— Nematinae, 205. 
— Odynerus: 

anormis, 231, 255. 

fzgr/^, 276. 
— Paniscus gemminatus, 285. 
— Pelopoeus cementarius, 214, 254. 
— Pitnpia: 

conquisitor, 214. 

inquisitor, 191. 



— Plesia interrupta, 255. 
— Polistes, 241, 266: 

variaius, 276, 297. 
— Pteronus ventralis, 667. 
— Scelipron cementarius, 285. 
— Scoliidae, 255. 
— Specodes dichroa, 231, 252. 
— Tachytes texanus, 255. 
— Thalessa atrata, 261. 
— Tragus vulpinus, 261. 
— Tiphia vulgaris, 286, 289, 290. 
— Vespa maculata, 192, 202, 256. 
— Xiphydria maculata, 207. 



Ice-sheet: Wisconsin, 45; advance and 
retreat, 43-46; drainage from, 45, 
46. 

Indians, 13. 

Insects: carriers of disease, 21; enemies 
of, 9, 10; human food, 21. 

Inter-mores physiology, 34, 35. 

Inter-physiology, 34, 35. 

Isle Royale, 195. 

Isopods. See Sowbugs. 

-Lacebugs, 232. 

Lake: Chicago, 45-47; Geneva, 62-63; 
Michigan, area, 73, bottom communi- 
ties, 78-81, communities, 73-85, condi- 
tions, 58-65, Ught, 63, pressure, 64, 
temperature, 62, species, 83-85; On- 
tario, 78; Pine, 67; Turkey, 67. 

Lake communities, 73-85, 124-36; sum- 
mary concerning, large lake, 81, small 
lake, 128, 131. 

Lake herring, 77. 

Lakes: circulation in, 60; distinguished 
from ponds, 124. 

Lampreys, 219. 

Larch or tamarack: sawfly, 195; lappet 
moth, 195; woolly aphid, 195. 

Lark: bunting, 286, 289; horned, 167, 
289; meadow, 167, 283, 289; shore, 
286. 

Larvae: lepidopterous, 167; sawfly, 167. 

Laws: minimum, 68; toleration, 302; 
limit of range, 304; distribution area, 
304- 

Lawyer, 82, 85. • 

Leaf-beetles, long-homed aquatic, 65, 
123, 135, 151- 

Leaf-bugs, hibernating, 202. 

Leeches: in Lake Michigan, 77, 80, 83, 
84; in lakes and ponds, 129; in 
streams, loi, 103. 



354 



ANIMAL COMMUNITIES 



Leeches, scientific names: 

— Clepsine, 84. 

— Dina fervida, 153. 

— Erpobdella punctata, 153. 

— Glossiphonia: 

fnsca, 123, 153. 

heteroclita, 153. 

slagnalis, 83. 
— Haemopis: 

gratidis, 103, 121, 153. 

marmoratis, 153. 
— Macrobdella decora, 135, 151, 153. 
— Placobdella: 

parasitica, 135, 148, 150, 153. 

rugosa, 117, 153. 
Lepidoptera, scientific names: 
—Acronycta oblinita, 188, 267. 
— A gratis ypsilon, 285. 
— Alypia octomaculata, 273. 
— Ampetophagus myron, 268. 
— Anisota senatoria, 241, 260. 
— Anthocharis genutia, 257. 
— Apantesis phatlerta, 285. 
— Basilarchia archippus, 251. 
— Certira, 232, 259, 279. 
— Datana, 199: 

angusii, 260. 
— Diacrisia virginica, 285. 
— Estigmena acraea, 284, 285. 
— Evetria comstockiana, 228, 229, 258. 
— Geometridae, 205. 
— Halisidota, 238, 260. 
— Hemileuca maia, 188, 268, 276. 
— Heterocampa guttivitta, 259. 
— Hydria undulata, 260. 
— /51a isabelia, 285. 
— Lencania unipuncta, 285. 
— Nadata gibbosa, 231, 233, 259. 
— Noctuinae, 204. 
— Papilio: 

ajax, 244. 

cresphontes, 268, 276. 

troilus, 244. 
— Pieris protodice, 220, 222. 
— Prionoxystus robiniae, 267. 
— Psychomorpha epimensis, 273. 
— Pyrameis: 

hunter a, 270. 

cardui, 270. 
— Samia cecropia, 199. 
— Scepsis fulvicoltis, 170, 284, 297. 
— Schizura, 268. 
— Symmerista, 199: 

albifrons, 200, 260. 
Licenses to collect animals, 57. 
Liebig's law of minimum, 68. 
Life histories: physiological, 33; repre- 
sented as circles, 71. 



Light: intensity, 159-60; necessity for 
food supply, 66; penetration in water, 
63; reactions to, 29, 251. 

Limnetic communities, 74-77, 103, 125, 

140. 
Living substance, 22. 
Lizard, six-lined, 227. 
Localities studied, 52-56. 
Locust: lesser, 227; long-horned, 227; 

lubbery, 262; mottled sand, 227; 

narrow-winged, 227; sand, 227. 
Logs: lake, 131; in ponds, 150; in 

streams, loi. 
Long-jaw, 79, 80, 82, 85. 

Maggots, 219. 
Mallard, 171. 

Mammalia, 2. 

Mammals, economic value of, 9, 10. 

Mammals, scientific names: 

— Bison bison, 289. 

— Blarina brevicauda, 201. 

— Canis latrans, 286. 

— Citellus: 

franklini, 269. 

13-lineatus, 228, 255, 286. 
— Fiber zibethicus, 156. 
— Geomys bursarius, 288. 
— Hominidae, 2. 
— Homo sapiens, 2, 319. 
— Lepus americanus, 191, 195. 
— Lutra canadensis, 195, 199. 
— Lynx rufus, 242. 
— Marmota monax, 215, 253. 
— Maries: 

americana, 196. 

pennanli, 196. 
— Mephitis mesomelas avia, 269. 
— Microtus: 

ochrogaster, 289. 

pennsylvanicus , 282. 
— Mustela: 

noveboracensis , 201. 

vison lutreocephala, igi. 
— Odocoileus virginianus, 238. 
— Peromyscus: 

bairdii, 286. 

leucopus noveboracensis, 201, 236. 
— Primates, 2. 

— Sorex personatus, 189, 201, 275, 269. 
— Tamias striatiis griseus, 269. 
— Taxidea taxus, 288. 
— Urocyon cinereoargenteus, 237. 
— Vulpes ftdvus, 236. 
— Zapus hudsonius, 269. 
Man, relation to animals, 5-20. 



INDEX OF SUBJECTS 



355 



Maps: evaporation, 50; frontispiece, ii; 
guide, (facing) 52; list of, 48; vegeta- 
tion, 51. 

Marsh communities, 169-73. 

Marten, pine, 196. 

Materials for abode, of land animals, 
157. 

May-flies, 65, 170. 

May-flies or Ephemerida, scientific names: 

— Baetis, 93. 

— Caenis, 114, 123, 155. 

— Callibaetis, 704, 123, 130, 135, 155. 

— Chirotenetes siccus, 117. 

— Ephemerella excrticians, 135. 

— Ephemeridae, 78. 

— Heptagenia, 93, 118. 

— Heptageninae, 96, 105, 114. 

— Hexagenia, 39, 103, 107, 117, 123. 

— Siphlurus, 96, 142, 155: 

altcrnatus, 98, 116. 
May-fly nymphs, 88. 
Metallic wood-borers, 191. 
Methane, 59, 60. 

Midge larvae: 69, 80, 129, 130; an- 
aerobic, 133. See Fly larvae. 
Midges, 170. 
Miller's thumb, 126. 
Mimicry, 25. 

Mineral matter: excessive in springs, 
93; necessary to life, 58. 

Mink, 15, 171, 191. 

Minnow: blackfin, 119, 120; black- 
head, 115; blunt-nosed, 79, 84, 115, 
119, 120, 126; Cayuga, 115, 119, 140; 
mud, 65, 84, 119, 120, 143, 149, 156; 
ruby faced, 119; shiner, 84; straw- 
colored, 79, 84, 126, 127, 135; sucker- 
mouthed, 119. 

Mites, aquatic, egg-laying of, ,129. 

Mites, aquatic, scientific names: 

— Hydrachna, 177, 185. 

— Limnochares aquaticus, 130, 144. 

Mites, terrestrial, scientific names: 

— Tromhidium, 190: 
sericeum, 207. 

Moisture: equivalent of soil, 158; re- 
lation to wilting coefiicient, 158. 

Mole cricket, 181. 

Moles: 167, 238; star-nosed, 282. 

Moilusca, 80, 106, 144. See Snails; 
Mussels; Sphaeridae. 

Moon, influence of," on plankton, 67. 

Moon-eye, 85. 

Mores, defined, 32. 



Mosquito: eaten by fishes, 132; fringe- 
legged, 174; marsh, 174, 176; smoky, 
178, 180. 

Mosquitoes, scientific names: 
— Aedes fusca, 178. 
— Anopheles, 114: 

punctipennis , 176. 
— Culex canadensis, 193, 206. 
— Culicidae, 185, 191. 
— Wyeomyia smithii, 193, 204. 
Mourning dove, 269, 274, 275. 
Mouse: Cooper's lemming, 195; deer, 
167; field, 167, 289; food of marten, 
196, of skunk, 269, of shrews, 269; 
meadow, 282; white-footed wood, 
201, 237; jumping, 269, 274. 
Mud puppy, 130. 
Muskrat, 14, 130, 156, 140, 143, 151, 

171. 
Mussels: 70; stunted on humus, 129. 
Mussels, scientific names: 
— Alasmidonta calceola, 99, 100, 116, 121. 
— Anodonta: 

grandis, 83, 103, 104, 126, 153. 

grandis Jootiana, 143, 153. 

marginata, 83, 126, 135, 140, 153. 
■ — A nodontoides: 

ferussaciamis , 39, 99, 100, 108, 117, 

127. 

ferussacianns snbcylindraceus, 100. 
— Lampsilis: 

ellipsiformis, 117, 121. 

iris, 117. 

liganteniina, 99, 117, 123. 

luteola, 99, 103, 117, 121, 122, 123, 

126, 129, 135, 140, 153. 

ventricosa, 99, 117, 122. 
— Quadrula: 

rubiginosa, 103, 117, 122, 123. 

undulata, 103, 117, 121, 122, 123. 
— Unio gibbosus, 103, 117, 122, 123. 
— Unionidae, 146, 153. 
— Symphynota: 

complanata, 122. 

costata, 122. 

Myriopods, viii, 215. 

Myriopoda, scientific names: 

— Fontaria corrugate, 215, 236, 237, 243, 

253, 254. 
— Geophilus, 200, 254. 

rubens, 217, 239, 243, 253. 
— Lithobius, 187, 191, 234, 239, 254. 
— Lysiopetalum lactarinm, 217, 239, 253 

254- 
— Polydesmidae, 215. 
— Polydesmus, 191, 205, 206, 234. 
— Scytonotus granulatus, 206. 



3S6 



ANIMAL COMMUNITIES 



Myriopoda — Continued: 

— Spirobolus marginalns, 201, 236, 237, 

243. 253. 
My sis relict a, 80, 81, 85. 

Natural selection, 25. 

Nature: 5, 6; man and, 8-20; man- 
made, 8; state of, 7; struggle in, 7, 

Neurpptera, scientific names: 

— Chauliodes, 123. 

rastricornis, 145, 148, 150, 155. 

— Chrysopa: 

albicornis, 297. 
oculata, 214, 291. 
rufialbris, 261. 

— Corydalis cornuta, 116, 121. 

— Cryptoleon nebulosmn, 283. 

— Mantis pa brunnea, 273, 274. 

— Sialis, 121. 

Newt, 121, 149, 156. 

Nitrates, 66. 

Nitrogen: 59, 60; cause of gas-bubble 
disease, 60; in lakes, 125; in spring 
water, 93. 

Number of individuals, relation to area 
of optimum, 303. 

Onion-fly, 293. 

Optimum, range of, 300-305. 

Oriole: Baltimore, 274, 275; orchard, 

274. 
Orthoptera, 243, 272, 285, 292, 306. 
Orthoptera, scientific names: 
— Acrididae, 187, 204. 
— Ageneotettix arenosus, 227, 252. 
— Amblycorypha, 205: 

oblongifolia, 208, 266, 267, 276. 

rotundifolia, 272. 

uhleri, 241. 
— Apithes agitator, 268. 
■ — Apterygida aculeata, 194, 205. 
— Atlanticus pachymerus, 239, 260. 
— Ceuthophilus, 205, 237, 239, 243. 
• — Chloealtis conspersa, 232, 259. 
— Conocephalus: 

ensiger, 232, 259, 298. 

nebrascensis, 264, 276. 

robustus, 265. 
— Cyrtophillus perspicillatus, 241, 260. 
— Diapheromera femorata, 187, 235, 241, 

257- 
— Dissosteira Carolina, 198, 214, 218, 254. 
— Gryllus pennsylvanicus, 218. 
— Hippiscus tuberculatus, 255. 
— Ischnoptera: 

inaequalis, 218. 

major, 218. 



— Melanoplus: 

angustipennis, 227, 252. 

atlanis, 225, 228, 252. 

bivittattis, 198, 218, 276, 285, 297. 

dijfferentialis , 266, 276. 

femnr-rubrum, 187, 214, 218, 223, 

276, 285, 296. 

punctidatiis, 194, 195, 205. 

viridipes, 297. 
— Nemobius: 

fasciatiis viltatus, 298. 

maculatus, 263, 297. 
— Neotettix hancocki, 190. 
— Oecanthus: 

angustipennis, 241, 260, 272. 

fasciatus, 232, 257, 272, 276. 
■ nivens, 272. 
— Orchelitnum: 

glaberrimum, 204, 208. 

indianense, 276. 

vulgare, 292, 296, 298. 
— Orphulella speciosa, 297. 
— Paratettix cucullatus, 181, 186. 
— Paroxya hoosieri, 204. 
— Psinidia fenestralis, 223, 225, 252. 
— Schistocerca rubiginosa, 232, 257. 
— Scudderia, 214, 217: 

furcata, 241, 266, 267, 276. 

texensis, 232, 259, 266, 277, 293, 

297, 298. 
— Sparagemon wyomingianum, 228, 252. 
—Stenobothrus, 170: 

curtipennis, 188, 204, 266, 285, 296, 

298. 
—Tettigidea: 

arniata, 181. 

parvipennis, 181, 282, 

pennata, 236, 282. 
—Tettix obscura, 190. 
— Trimerolropis maritima, 223, 252. 
— Xiphidium, 170: 

brevipenne, 188, 208, 263, 266. 

ensiferum, 215. 

fasciatum, 39, 188, 263, 264, 284, 

285, 296. 

nigropleura, 263, 276. 

strictum, 232, 259, 292, 293, 298. 
Osprey, 226. 
Ostracods, 129. 

Ostracods or Ostracoda, scientific names: 
— Cypria exsculpta, 152. 
— Cypridopsis vidua, 130, 152. 
— Cypris fuscata, 185. 
—Cyprois marginata, 177, 179, 185. 
— Notodromas nionacha, 144. 
— Ostracoda, 144. 
— Potamocypris smaragdina, 134. 

Otter, 195, 199. 
Oven-bird, 244. 



INDEX OF SUBJECTS 



357 



Owl, screech, 229. 

Oxygen: anaerobic animals, 133; bur- 
rowing dragon-fly nymphs, 142; circu- 
lation of, 61; correlated with age of 
ponds, 68-70; in lakes, 125, 133; in 
pools, 91; in springs, 93; in streams, 
103; intermittent quantities, 90; neces- 
sary in water, 59; not added by certain 
plants, 65; reduced by sewage, 17. 



Panther, 15, 238, 242, 

Partridge, 196, 

Perch: pirate, 120; yellow or American, 
85, 99, 119, 120, 126, 130, 156; trout- 
perch, 84. 

Pest species, number of, on different 
forest trees, 166. 

Pewee, wood, 242, 244. 

Phalangids, 167. 

Physiological agreement of communities: 
34; life histories, 2>yy proportionality 
in organisms, 26. 

Physiological equihbrium: 26; distrib- 
uted by changes in the organism, 30, 
by external conditions, 30; in relation 
to habitat, 31. 

Pickerel, grass, 105, 115, 142, 156. 

Pike: 85, 115, 120, 140; pike-perch, 85; 
wall-eyed, 85. 

Pintail, 171. 

Planarians, in Lake Michigan, 77. 

Plankton: in arctic seas, 66; proportion 
to denitrification, 66; relation to tem- 
perature, 66, to CO3, 67, 68, to oxygen, 

67, 68, to carbonates, 67, 68, to rate of 
flow, 67, to seasons, 67, to age of ponds, 

68, to moon, 67. 

Plants, aquatic: in sandy riffles, 99; in 
sluggish streams, 104; value of, to 
animals, 65, 142; watercress, 93. 

Plants, aquatic, scientific names: 

—Chara, 64, 65, 74, 142, 145, 148. 

— Cladophora, 64, 74. 

— Elodea, 65, 129. 

— Equisetum, 65, 151. 

— Myriophyllum, 65, 129, 130, 131, 145. 

— Nostoc, 74. 

— Potamogeton, 145. 

— Proserpinaca, 151. 

Plants, terrestrial, scientific names: 

— Arabis lyrata, 228. 

— Citrus, 257. 

— Gossypium, 257. 

— Hibiscus, 189. 

— J uncus balticus, 173. 



— Monarda, 228, 232. 

— Opuntia, 255. 

— Parnassia caroliniana, 182. 

— Pinus banksiana, 228. 

— Sagittaria, 175. 

— Tilia, 257. 

Plover, piping, 180. 

Polyzoa, scientific names: 

— Fredericella sultana, 84. 

— Paludicella ehrenbergii, 84. 

— Peclinatella magnifica, 128, 130, 135. 

— Plutnatella, 84, 103, 121, 131: 

polymorpka, 135. 
Polyzoan, gelatin-secreting, 128, 129. 
Pond animals in streams, 102, 103. 
Pond communities: 136-57; temporary, 
173-80. 

Ponds, vernal or temporary: forest, 179; 
snails of, 192; influence of rainfafl on, 
i77~79; vegetation choked, 174; young, 
with bare bottom, 173. 

Porcupine, Canada, 196. 

Prairie chicken, 167, 289. 

Prairie communities, 278-98. 

Pressure of water, 64. 

Protected situation of large lake, com- 
munities of, 80. 

Protection of wild animals: 8-1 1; pro- 
tected species, 56, 57; wardens, 57. 

Proteid, foodstuffs, 66. 

Protozoa: 129, 130; anaerobic, 133; 
as animal food, 20; producers of disease, 
20. 

Protozoa, scientific names: 

— Actinophrys sol, 75. 

— Difflugia: 

globulosa, 75. 
Pyriformis, 132. 

—Peridinium tabulatum, 75. 

Psocus, 234. 

Pulmonate snails, aquatic respiratioji 

of, 129. 
Pumpkin-seed, 84, 156. 
Puss caterpillar, behavior of, 232. 

Quantity: of larger animals, 69; of life 
on land, 166; of plankton: causes of 
fluctuations in, 72; in different bodies 
of water, 67; in ponds of different 
ages, 69; in polar regions, 66; seasonal 
variation in, 67, 

Rabbit: 196; cottontail, 269, 275. 
Raccoon: 199, 202; eats crayfishes, 90. 



358 



ANIMAL COMMUNITIES 



Rail: king, 171; sora, 171; Virginia, 171. 
Rapids: communities of intermittent, 

87; formation of, 94-99. 
Rattlesnake, 167. 
Reactions: defined, 26; positive and 

negative, 26; to current, 34, 91, 95, 

loi, 106, 107. 
Red-legged locust, 266. 
Redstart, 274, 275. 
Regulation in behavior, 29. 
Rejuvenation of streams, 108. 
Relations of communities, 308-15. 
Reptiles: economic value of, 10, 21; in 

timber and prairie, 15. 
Reptiles, scientific names: 
— Cnemidophoriis 6-lineatus, 227, 252. 
— Coluber constrictor, 255. 
— Crotalus durissus, 237. 
— Heterodon platirhinos, 255. 
— Liopeltis vernalis, 289, 299. 
— Sistruriis catenatus, 204, 289. 
— Thamnophis, 150: 

radix, 283, 288, 296. 
— Tropidonotus grahamii, 283. 
Responses, to day and night, to weather, 

to seasonal changes, 31. 
Rheotaxis: AUee on, 327; Lyon on, loi; 

of fishes, 34, 91, 92, 95, loi; of isopods, 

92; of moliusks, 106, 107; of stream 

animals, 91, loi. 
Rivers, drowned and sluggish, 102, 103. 
Roadsides, 13, 275. 
Rotifers: 65; diurnal migration of, 77; 

of Lake Michigan, 75-77; sessile, 131. 
Rotifers, scientific names: 
— Dinocharis tetractis, 84. 
— Notops: 

pelagiciis, 76. 
pygmaeus, 77. 
— Rotifer elongatus, 84. 
Roundworms, in Lake Michigan, 77. 

Salamanders: four-toed, 237; spotted, 
149, 278, 282, 296; sticky, 181, 183, 
207; red-backed, 197, 243, 255. 

Sandpiper, spotted, 180, 181. 

Scorpion-flies, 202. 

Scorpion-flies, scientific names: 

— Bittacus, 202: 
strigosus, 208. 

— Panorpa, 40, 191: 
venosa, 200, 208. 

Seasons: Relation of animals to, 31; 
succession with, 36, 278; quantity of 
plankton in, 67. 



Sediment, in water, relation to light pene- 
tration, 63. 

Seeds, as animal food, 167. 

Segregation of species, vertical in Lake 
Michigan, 82. 

Seines, illegal, 57. 

Selection of habitat: 300-305; law of 

toleration in, 302-5. 
Sessile animals, food of: 97; in sea, 309; 

motile animals compared with, 309. 
Sewage, effect of: upon stream animals, 
17; upon oxygen content, 17; upon 
plankton, 17. 
Sheepshead, 85. 

Shiner: 79, 84; common, 115, 119, 120, 
140; golden, 65, 102, 115, 119, 120, 142, 
143, 156. 
Shore-bugs, 180. 
Shores, sandy: of large lakes, 78; of 

small lakes, 125, 126. 
Shrew: common, 189, 191, 196, 201, 262, 

269, 274; short-tailed, 201. 
Shrike, loggerhead, 275. 
Shrimps, scientific names: 
— Eubranchipus, 177, 178, 179, 278: 

serratus, 185, 279. 
— Palaemonetes pahidosus, 126, 130, 135, 

152. 
Silversides, 85, 130, 135. 
Skunk, 12, 15, 169, 199, 262, 274. 
Slug caterpillar, 233. 
Slugs, scientific names: 
— Agriolimax campestris, 199, 200, 202, 

205, 236. 
— Pallijera dorsal is, 256. 
— Philomycus carolinensis, 206, 215, 240, 

241, 243, 247, 253, 254. 
Smeared dagger- moth, larva of, 190. 
Snails: aquatic, 90; in lakes, 130; reac- 
tions of, to light, 29; reactions of, to 
water current, 34. 
Snails, aquatic, scientific names: 
— Amnicola, 80, 148: 

cincinnatiensis , 117, 154. 
emarginata, 83. 

limosa, 83,99, "7, 121, 145, 146, 154. 
limosa parva, 1 54. 
limosa porata, 83. 
lustrica, 83. 
walkeri, 84. 
— Ancylus, 130: 
fusctis, 135. 
rivularis, 121. 
tardus, 121. 
— Aplexa hypnorum, 192. 



INDEX OF SUBJECTS 



359 



Snails — Continued: 

— Campeloma, 99, 103, 104, 106: 

integrum, 107, 108, 117, 123. 

subsolidum, 100, 117. 
— Goniobasis, 103: 

livescens, 95, 98, 103, 116, 121, 123, 

126, 135. 
— Lymnaea, 84, 104, 131, 145: 

exigua, 173, 185. 

lanceata, 85. 

modicella, 114, 121, 154, 174, 181, 

186, 187. 

obrussa, 1^4. 

reflexa, 147, 149, 154, 174, 175, 185, 

189. 

reflexa exilis, 154. 

stagnalis, 83. 

woodrtiffi, 79, 80, 84. 
— Physa, 145-15 1 : 

gyrina, 93, 114, 118, 121, 131, 135, 

154, 173, 185. 

heteroslropha, 154, 173. 

integra, 104, 117, 131. 
— Planorbis, 173, 185. 

bicarinatus, 39, 83, 99, 104, 117, 121, 

123, 154- 

campamilatus, 114, 131, 135, 147, 149, 

154- 

defleclus, 154. 

exacuosus, 154. 

exacutus, 83. 

hirsutus, 148, 149, 154. 

parvus, 116, 131, 135, 148, 149, 154, 

204. 

trivolvis, 16, 149, 150, 152, 154. 
— Pleurocera, 99, 103: 

elevatum, 106, 107, 108, 121, 123. 

elevatum lewisii, 117. 

subulare, 39, 126, 127, 135. 

subulare intensum, 121. 
— Pleuroceridae, 84. 
— Segmentina armigera, 131, 135, 154. 
—Valvata, 80: 

bicarinata perdepressa, 83. 

sincera, 83. 

tricarinata, 83. 
— Vivipara contectoides, 126, 128, 152. 
Snails, hibernation of, 192. 
Snails, terrestrial, scientific names: 
— Circinaria concava, 200, 204, 206, 237. 

253- 
— Omphalina fuliginosa, 253. 
— Polygyra: 

albolabris, 197, 207, 215, 237, 243, 254. 

clausa, 200. 

fraudulenta, 243, 256. 
• inflecla, 234, 256. 

monodon, 190, 213, 215, 254, 263. 

ntuUilineala, 206, 234. 



oppressa, 243, 256. 

palliata, 243, 256. 

pennsylvanica, 236, 237. 

profunda, 200, 202, 215, 236, 237. 

thyroides, 200, 202, 208, 213, 215, 

234, 252, 254. 
— Pyramidula, 214, 215, 243: 

alternata, 192, 200, 236, 237, 243, 247, 

253, 254. 

perspectiva, 256. 

solitaria, 236, 237, 243, 256. 

striatella, 190. 
— Succinea: 

avara, 187, 199, 202, 208, 282. 

ovalis, 208, 263, 264. 

retusa, 169, 187, 189, 199, 202, 204, 

208. 
— Vitrea indentata, 205. 
— Zonitoides, 215: 

arboreus, 190, 206, 234, 236, 243, 247, 

253, 306. 
Snakes, food of skunks, 269. 
Soil: 157-59; effect of, on organisms, 
159; factor in distribution, 301; 
humus, 158-59. 

.Sowbugs or Isopoda, aquatic, scientific 

names : 
— Aselhis communis, 90, 98, 114, 121, 

154, 174- 185, 206. 
— Mancasellus danielsi, 135, 154, 174. 
Sowbugs, terrestrial, scientific names: 
— Cylisliciis convexus, 239, 253. 
— Porcellio rathkei, 200, 240, 254, 253. 
Sparrow: chipping, 274, 275; field, 274, 
275; grasshopper, 167, 289; lark, 275; 
song, 262, 268, 275; vesper, 167. 
Sparrow-hawk, 274. 
Species, animal: i; number of, i; plant, 

i; use in ecology, 3. 
Sphaeridae, scientific names: 
— Calyculina transversa, 83. 
■ — Musculium, 118, 179, 189. 

partumeium, 147, 153. 

secure, 147, 153, 185. 

truncatum, 121, 147, 153. 
— Pisidium, 81 : 

compressum, 83. 

idahoense, 83, 133. 

punctatum, 83. 

scutellatum, 83. 

variabile, 83. 

ventricosum, 83. 
— Sphaeridae, 69, 80, 83, 100, 103, 147, 

151, 153- 
— Sphaerium, 108: 

slamineum, 107, 116, 121. 
slriatinum, 80, 83, 116. 
vermontanum, 79, 84. , 



36o 



ANIMAL COMMUNITIES 



Spherid, anaerobic, 133. 
Spiders, 167. 
Spiders, scientific names: 
— Acrosoma: 

gracilis, 238, 240, 260. 

spinea, 238, 240, 260. 
— Agelena naevia, 207, 218, 254, 296. 
— Anyphaena cons per sa, 260. 
— Argiope: 

aurantia, 263, 264, 276, 296. 

trifasciata, 204, 205, 208, 232, 259, 

263, 293, 296, 298. 
— AUus paluslris, 276. 
— Atypus milberti, 277. 
— Castianeira cingulata, 197, 207. 
— Chiracanthium inclusa, 187, 205. 
— Clubiona obesa, 277. 
— Dendryphantes: 

militaris, 205, 206. 

octavus, 204, 205, 206, 228, 258. 
— Dictyna: 

foliacea, 206, 208, 228, 232, 257, 276. 

sublala, 187, 204, 207. 
— Dictynidae, 257. 
— Dolomedes: 

sexpunctatus , 146, 169, 187, 283, 296. 

tenebrosus, 243. 
— Epeira, 198, 232: 

domicilorum, 240, 257, 306. 

foliata, 187, 204, 206. 

gigas, 194, 205, 206, 208, 240, 257, 272. 

ocellata, 206. 

prompta, 204. 

trifolium, 205, 276, 277, 296. 

trivittata, 188, 205, 214, 276, 284, 293, 

296. 
— Epeiridae, 208, 257, 260. 
— Encta caudata, 187. 
— Eugnatha straminea, 204, 296. 
— Gayenna celer, 260. 
— Geolycosa pikei, 220, 227, 230, 250, 252. 
— Habrocestum pulex, 206. 
— Hypselistes florens, 207. 
— Leucauge hortorum, 202, 208. 
— Linyphia phrygiana, 260. 
— Lycosidae, 261. 
— Maevia niger, 260, 277, 298. 
— Mangora maculaia, 206, 260. 
— Misumena vatia, 214, 264, 285, 296. 
— Misumessus: 

asperatus, 231, 232, 257, 293. 

oblongus, 207. 
— Notion ell a inter pres, 261. 
— Ozyptila conspurcata, 296. 
— Pardosa, 215: 

lapidicina, 213, 214, 215. 254. 
— Phidippiis: 

aiidax, 207, 264. 

borecUis, 297. 



podagrosus, 204, 293, 298. 

rufus, 298, 
— Philodromus: 

alaskensis, 223, 228, 257. 

ornatus, 205. 

pernix, 259. 
— Pirata: 

insularis, 187. 

montana, 204. 

piratica, 206. 
— Pisauridae, 204. 
— Pisaurina, 198: 

undata, 204, 206, 208, 277. 
— Plectana stellata, 204. 
— Runcinia aleatoria, 204, 214, 277, 293, 

296. 
— Singa variabilis, 276. 
—Tetragnatha: 

grallator, 205, 206. 

laboriosa, 169, 187, 208, 263, 276, 

284, 285, 296. 
— Thertdiidae, 257. 
— Theridium: 

frondeum, 191, 202, 206, 208, 240, 

257, 258. 

spirale, 228, 258. 
— Thiodina puerpera, 204. 
— Thomisidae, 257. 
— Tibellus duttoni, 187, 204. 
— Trochosa cinerea, 222, 252. 
— WTa/a mitrata, 261. 
— Xysticus formosus, 228, 258. 
— Zygoballus bettini, 206. 
Spittle insects, habits of, 202. 
Sponge, abundant in stream, 97. 
Sponges, scientific names: 
— Heteromeyenia argyrosperma, 153. 
— Meyenia: 

crateriformis, 153. 

flumatilis, 153. 
— Spongilla, n6, 131: 

fragilis, 153. 
Spontaneous movement, 26. 
Springtails, 180. 

Squirrels: 233; fox, 245; Franklin 
ground, 269, 274; gray, 192, 202, 245; 
ground, 167, 227, 286; red, 245. 
Stations of study, 50, 51-56. 
Statoblast, 129. 
Stickleback, 85. 
Stimulus, defined, 26. 
Stinkbugs, hibernating, 202. 
Stonecat: 119; slender, 95. 
Stone-fly nymphs, scientific name: 
— Perla, 78, 116, 121. 
Stone-roller, 119, 120. • 



INDEX OF SUBJECTS 



361 



Stones: in water, 78, 88, 95-97; currents 
about, 61. 

Strata: defined, 37; in aquatic vegetation, 
105; in rapids, 94-96; on land, 165. 

Stream communities: 78, 86-123; base- 
level, 102-5; intermittent, 87-92; 
longitudinal arrangement of, 108-23; 
sandy, 101-2; sluggish, 102-5; spring- 
fed, 93; swift, 93-99. 

Struggle for existence, 5-6. 

Sturgeon, 85. 

Succession: autoproductive, 308; causes, 
308; defined, 36; ecological, 36; 
forest, 247-50; geological, 36; lake, 
135; pond, 152; seasonal, 35, 36, 
278; stream, 1 10-13. 

Sucker: carp, 85; chub, 115, 119, 142, 
156; common, 84, 91, 92, 106, 115, 
119, 120; long-nosed, 84; hog or stone- 
roUer, 84, 119; red-horse, 84, 115, 119, 
140; short-headed red-horse, 120. 

Sunfish: bluegill, 84, 99, 115, 119, 120, 
126, 156, 141; blue-spotted or green, 
102, 119, 120, 126, 128, 156, 141; 
long-eared, 99, 119; pumpkin-seed, 
126, 156, 141. 

Swallow: bank, 222; tree, 225. 

Swamp communities, 169-73, 189-97. 

Tadpole catfish, 85, 105, 119, 142. 

Tamarack swamp communities, 193-97. 

Tanager, scarlet, 244. 

Taxis, 26, 27. 

Temperature: of soil, 158-59; habitat 

compared, 159; control of distribution, 

199-304. 
Temporary ponds, 1 73-80. 
Tension Unes between land and water, 

169-88. 
Terminology of ecology, 36-38. 
Termites, 220-22. 
Termites, scientific name: 
— Termes flavipes, 220, 252. 
Tern, black, 170. 

Terrestrial conditions, 169-88, 247-50. 
Thicket communities, 262-75. 
Thrush: hermit, 195; wood, 241, 244. 
Thysanoplera, 306. 

Tiger-beetles, 180, 216; larvae, 210, 214, 
216. 

Toad: 167, 187, 283, 296; daily habits, 

222. 
Toadbug, 180. 



Toleration, law of, 302-5. 

Tolleston beach, 47. 

Top minnow, 84, 120, 123, 132, 135. 

Toxic substances, in soil, 159; in water, 
331 (114, 1140)- 

Transparent animals, 77. 

Tree-fauna, differs with surrounding 
conditions, 16, 251. 

Trespass laws, 56. 

Tropism, 26, 27. 

Trout, Mackinaw or Lake, 59, 78, 79, 
80, 82, 85. 

Turkey, wild, 14. 

Turtles: geographic, 130, 135, 156; 
habits of, 130; musk, 126, 130, 135, 
142, 156, breeding of, 130; painted, 
132, 156, 227; protected by law, 57; 
snapping, 132; soft-shelled, 130; trans- 
portation of animals by, 173. 

Turtles, scientific names: 

— Aromochelys odorata, 126, 135, 142, 
156. 

— Aspidonedes spinifer, 130. 

— Chrysemys marginata, 132, 156, 227. 

— Graptemys geographictis , 130, 135, 156. 

Upstream migration: of fishes, 106; of 
mollusks, 106. 

Valparaiso Moraine, 46. 

Variation of behavior and habits related 

to conditions, 34. 
Varying hare, 15, 191, 195. 
Vegetation: aquatic, 65 {See Plants); 

climatic, 49, 50, 51, 174. 
Vernal fauna, 173-80. 
Vertebrata, 2. 

Vertebrates, products from, 21. 
Vireo, red-eyed, 196, 244. ' 

Warbler: black, 241; blackbumian, 196; 

black-throated, 229; green, 229; pine, 

229; prothonotory, 190, 191; yellow, 

196, 241, 274, 275. 
Water in soil, 157-58. 
Water margin communities: 180-83; 

sedge-covered, 181; shrub-covered, 

181; terrigenous, of large lakes, 180, 

of ponds, 180, of rivers, 181. 
Water scavenger beetles, 65. 
Water-scorpions, 65, 104, 123, 131, 151, 

155- 
Water-striders : 90; hibernation of, 201. 



362 



ANIMAL COMMUNITIES 



Water-striders, scientific names: 
— Gerridae, 185. 
— Gerris: 

marginatics, 155. 
rufoscutellatus, 155. 
— Mesovelia bisignata, 155. 
— Rhagovelia coUaris, 98, 117. 
Weasel, 201. 
Weeds, avoided by aquatic animals 

during flood, 105. 
Weevils, 167. 

Wheel animalcules. See Rotifers. 
Whitefish: 76, 77, 82, 85; blackfin, 81, 

82; Hoy's, 81, 82, 85; long-jaw, 79, 

80, 82, 85. 

Willow blossoms, visited by pollen- 
gathering insects, 224-25. 
Willow sawfly: large, 267; spotted, 267. 
Wildcat, 242. 
Wilting coefficient of soil, 158. 



Wind : influence on circulation in lakes, 
61; relation to light penetration, 63, 
to evaporation, 160, 162, 163. 

Wolf, 15, 167, 201, 236, 238, 245. 

Wood pewee, 196, 244. 

Wood thrush, 241. 

Woodchuck, 215, 233, 236. 

Woodcock, 189, 191. 

Wood-frog, 244. 

Woodpeckers: 196, 274; downy, 229; 
in beach drift, 219; red-headed, 242. 

Worms: flat, 20; round, 20. 

Wren: long-billed marsh, 171; short- 
billed marsh, 181. 

Yellowlegs, 181. 

Yellowthroat, northern, 189, 262, 275. 

Zonation in forest edge, 263. 



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AWIMAL COMMUNITIES IN 
TEMPERATE AMERICA M 

by Victor E. Shelford 


N 



ANIMAL COMMUNITIES IN 
TEMPERATE AMERICA 

by Victor E. Shelford 



FOftESTA iNSTtrurc 

^\ OCEAN 



MOUNTAIN 
STUDIES 

6205 FRANKTOWN ROAO 
CAMON CITY, NfVMDA tvm