Table Of ContentSEXUAL SEGREGATION IN UNGULATES
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Wildlife Management and Conservation
Paul R. Krausman, Series Editor
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Sexual Segregation
in Ungulates
Ecol ogy, Be hav ior, and Conservation
R. TERRY BOWYER
Published in Association with THE WILDLIFE SOCIETY
JOHNS HOPKINS UNIVERSITY PRESS | BALTIMORE
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© 2022 Johns Hopkins University Press
All rights reserved. Published 2022
Printed in the United States of Amer i ca on acid- free paper
9 8 7 6 5 4 3 2 1
Johns Hopkins University Press
2715 North Charles Street
Baltimore, Mary land 21218
www . press . jhu . edu
Library of Congress Cataloging- in- Publication Data
Names: Bowyer, R. Terry, author.
Title: Sexual segregation in ungulates : ecol ogy, be hav ior,
and conservation / R. Terry Bowyer.
Description: Baltimore : Johns Hopkins University Press,
2022. | Series: Wildlife management and conservation |
Includes bibliographical references and index.
Identifiers: LCCN 2021063011 | ISBN 9781421445069
(hardcover) | ISBN 9781421445076 (ebook)
Subjects: LCSH: Ungulates— Be hav ior. | Spatial be hav ior
in animals. | Sex discrimination.
Classification: LCC QL737.U4 B69 2022 | DDC 599.6—
dc23/eng/20220120
LC rec ord available at https:// lccn . loc . gov / 2021063011
A cata log rec ord for this book is available from the British
Library.
Special discounts are available for bulk purchases of this
book. For more information, please contact Special Sales
at specialsales@jh . edu.
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To my wife, Karolyn
Nothing would be pos si ble or enjoyable without her love and support
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Contents
Preface ix The Role of Resources and Predation Risk
Acknowl edgments xiii in Gregariousness 31
Resources and Topography 31
1 Introduction and Overview 1 Predation 33
Historical Perspectives 1
3 Temporospatial Patterns 43
Ungulate Characteristics and Relevant
Defining Social Groups 43
Aspects of Their Beh avi or, Ecolo gy,
Attributes of Groups 44
and Conservation 2
Types of Social Groups 46
Distribution, Habitats, and Body Size 2
Temporal Patterns of Sexual Segregation
Diets and Digestive Systems 2
and Aggregation 48
Mating Systems 3
Spatial Patterns of Sexual Segregation 50
Life- History Characteristics, Population
Patterns on the Landscape 50
Dynamics, and Movements 4
Forage and Habitat Use, Se lection,
Predator Pits, Apparent Competition, and
and Quality 51
Territorial Regulation of Populations 5
Density Effects 55
Effects on Plants, Animals, and Nutrient
Cycling 7 4 Detection and Mea sure ment 59
Trophic Cascades 8
Detecting Sexual Segregation 59
Cultural and Historical Relationships with
Mea sur ing Sexual Segregation 60
Ungulates 9
Segregation Coefficients 60
Challenges Today and Future Unknowns 10
Sexual Segregation and Aggregation
Sexual Segregation in Plants and Animals 12
Statistic 62
Tests of Ratios and Proportions 63
2 Differences between the Sexes 21
Multi- response Permutation Procedures 63
Definitions of Sexual Segregation 21
Information- Theoretic and Machine- Learning
Sexual Differences in Morphology, Physiology,
Approaches 63
and Foraging Be hav ior 22
Effects of Scale 64
Sexual Dimorphism 22
Habitat Se lection, Home Ranges, and
Teeth Morphology and Diet 28
Scale 64
Gastrointestinal Characteristics and Related
A Synthetic Approach 67
Physiology of Ruminants 29
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viii contents
5 Failed Concepts 73 Predation- Risk Hypothesis 99
Setting Aside Rejected Hypotheses 73 Multiple Causations and Tradeoffs 100
Social Hypotheses 73
8 Consequences of Sexual Segregation for
Ecological Hypotheses 76
Theory and Management 104
Limiting Overutilization of Habitats 78
Paternal Investment and Sexual Se lection 104
Problematical Speculations 78
Population Dynamics 105
Reproductive- Strategy Hypothesis 78
Forage- Selection Hypothesis 79
9 Failing to Consider Sexual
Proximate Causations 79
Segregation 117
Avoiding More Speculation 81
Moose 117
6 The Role of Social Be hav ior 84 North American Elk 119
White- Tailed Deer 120
Social Aggression and Sexual Affinities 84
Bighorn Sheep 122
Activity Patterns 86
A Case Study of Mule Deer 88
10 The Future 128
Criticisms of the Activity-P attern
Defining Sexual Segregation 128
Hypothesis 90
Why Is Sexual Segregation Overlooked? 129
The Social- Constraints Hypothesis 91
Future Questions and Directions 131
7 Ecological Aspects of Sexual Relevance to Other Organisms 133
Segregation 93
Competition Hypothesis 94 Lit er a ture Cited 137
Gastrocentric Hypothesis 97 Index 177
Niche- Partitioning Hypothesis 98
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Preface
For as long as I can remember, I have been fascinated I was fortunate that my master’s research at Hum-
with large mammals. I suspect this attraction origi- boldt State University was supervised by David W.
nated with my dad taking me out of school so I could Kitchen, an accomplished animal behaviorist who
accompany our extended f amily on hunting trips for had just published his seminal monograph on prong-
mule deer in California’s Sierra Nevada. At that time, horn. Dave was among a group of biologists begin-
I was far too young to carry a r ifle. Nevertheless, I ning to integrate social be hav ior with ecol ogy. He
read everyt hing I could about hunting, and when ma- convinced me to spend time watching Roos e velt elk
ture enough to hike through rugged terrain and shoot at Gold Bluffs Beach in northern California, helped
straight, I joined my dad hunting mule deer and quail me to understand elk beh avi or, and assisted with de-
in the mountains outside of Ojai in southern Califor- veloping my critical thinking skills. My MS thesis
nia. Early on, my enjoyment of hunting helped me concerned several aspects of elk beh avi or, but again,
decide that I wanted to work with large mammals. it was restricted to observations during rut. I realized
I was studying for my BS degree in wildlife man- that much of what we understood about animal
agement, however, before I recognized that being beh avi or was not cast in an evolutionary perspective,
a hunter, although teaching me field craft, was only a and there were many unanswered questions con-
small part of what was required to be a scientist. Nev- cerning the links between ecolo gy and beh avi or.
ertheless, without that early background, I might I did not become aware of sexual segregation
never have become a field biologist. until I was studying southern mule deer in the
I initially was not interested in sexual segregation; Cuyamaca Mountains of southern California for my
I never recognized that this topic was a major com- doctoral dissertation at the University of Michigan
ponent in the life histories of many large mammals (UM). My dissertation tested hypotheses about how
(incidentally, hunters are not the only ones who lack resources and risk of predation helped shape the so-
this appreciation). I had spent much of my time in cial organi zation of mule deer. My major professor,
the field during autumn hunting seasons, which co- Dale R. McCullough, was studying the population
incided with rut, when the sexes were mostly aggre- ecolo gy of white-t ailed deer in southern Michigan
gated. Later on, I began to enjoy watching animals, when I arrived at the UM. A fter several years of rig-
especially ungulates, without disturbing them, and orous coursework and thought-p rovoking discus-
I was becoming increasingly more curious about sions, I fin ally had my fieldwork well underway and
their be hav iors. was pursuing what I hoped would be cutting- edge
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