Landscape and anthropogenic effects on mammal occupancy in the Appalachian Trail corridor

58 Pages·2016·1.06 MB·English

University of Colorado, Boulder
CU Scholar
Ecology & Evolutionary Biology Graduate Theses &
Ecology & Evolutionary Biology
Dissertations
Spring 1-1-2012
Landscape and anthropogenic effects on mammal
occupancy in the Appalachian Trail corridor
Peter Lowell Erb
University of Colorado at Boulder, [email protected]
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LANDSCAPE AND ANTHROPOGENIC EFFECTS ON MAMMAL OCCUPANCY
IN THE APPALACHIAN TRAIL CORRIDOR
by
Peter Lowell Erb
B.A., Colorado College, 2004

A thesis submitted to the
Faculty of the Graduate School of the
University of Colorado in partial fulfillment
of the requirement for the degree of
Master of Arts
Department of Ecology and Evolutionary Biology
2012
This thesis entitled:
Landscape and anthropogenic effects on mammal occupancy in the Appalachian
Trail corridor
written by Peter Lowell Erb
has been approved for the Department of Ecology and Evolutionary Biology

Dr. Robert Guralnick, advisor and committee chair

Dr. Sharon Collinge, committee member

Dr. Carol Wessman, committee member

April 10, 2012

The final copy of this thesis has been examined by the signatories, and we
Find that both the content and the form meet acceptable presentation standards
Of scholarly work in the above mentioned discipline.
iii

Erb, Peter Lowell (M.A., Ecology and Evolutionary Biology)

Landscape and anthropogenic effects on mammal occupancy in the Appalachian
Trail corridor
Thesis directed by Associate Professor Robert P. Guralnick

Anthropogenic and landscape effects on wildlife are typically assessed at the local or
patch level, but such effects are often difficult to extrapolate to larger spatial
extents. Studies that examine broad-extent effects of anthropogenic disturbances,
fragmentation and habitat loss on mammal occupancy are uncommon and yet
much-needed. Macro-level occupancy studies are one way to assess anthropogenic
and landscape factors that vary and interact over different geographic extents. Here
we assess anthropogenic and landscape effects on occupancy and distribution for
several mammal species within the Appalachian Trail (AT), a forest corridor that
extends across a broad section of the eastern United States. Utilizing camera traps
and a large volunteer network of citizen scientists, we were able to sample 447 sites
along a 1024 km section of the AT. To assess anthropogenic influences on mammal
occupancy we investigated the effects of available habitat, hunting, recreation, and
roads on eight mammal species. Landscape effects were measured by investigating
the influence of available habitat, patch area, isolation, edge and connectivity on
five carnivore species. Occupancy modeling revealed that available habitat was
among the top predictors of occupancy for nearly all mammal species.
Anthropogenic effects were well represented in the top models, with hunting being
the strongest predictor of mammal occupancy. Landscape configuration metrics
iv

(patch area, isolation, edge, and connectivity) were not well represented in the top
models. The total amount of edge was the only landscape metric to influence the
occurrence of three carnivore species: bear, coyote, and raccoon. Our study
highlights the importance of forest cover to mammal species, regardless of
configuration within the landscape or the anthropogenic disturbances in the AT
corridor. This study also stresses the importance of compounding direct and indirect
anthropogenic influences operating at the regional level. Scientists and managers
should consider these impacts and their potential combined influence on wildlife
persistence when assessing optimal habitat or considering management actions.
v

ACKNOWLEDGEMENTS

The completion of this thesis could not have been completed without the help of
numerous people. I would like to thank the many people within the Department of
Ecology and Evolutionary Biology at CU for their time and guidance throughout
this process. I could not have asked for a better advisor and committee while
working on this thesis and am extremely grateful to Robert Guralnick, Carol
Wessman, and Sharon Collinge for their continued support. I am also thankful to
Chris Ray and Larissa Bailey who were always accessible and gracious enough
answer my toughest modeling questions. The administrative staff within the
department has also been extremely helpful including Jill Skarstad, Bill Franz,
Melanie Green, and Linda Bowden. Most of all I would like to thank my lab mate,
best friend, and wife, Liesl Erb, for the unlimited love and support through this
roller coaster of a ride called graduate school.
I would also like to acknowledge the Smithsonian and the people at the
Conservation Biology Institute that made this all possible. Without the guidance of
Dr. William McShea, my development as a conservation biologist would never have
materialized. I am extremely grateful for his patience and willingness to work with
me over the last few years. I would like also like to give a special thanks to all my
comrades at the Conservation Biology Institute throughout the years, including
Megan Baker, Connor Fitzhugh, Allie Hunter, Ryan Bechtel, Sumana Serchan, and
the many, many other coworkers I was fortunate enough to work with.
vi

A huge acknowledgement must also go out to all the people involved in
making this one of the largest and most successful citizen science projects on record.
I want to give a special thanks to Laura Belleville and Robert Picket for aiding in
volunteer recruitment and training and to the hundreds of invaluable volunteers
that made this project possible.
vii

CONTENTS

CHAPTER

I. Anthropogenic influences on macro-level mammal occupancy
in the Appalachian Trail corridor ......................................... 1

Abstract .................................................................................. 1

Introduction ........................................................................... 2

Methods .................................................................................. 5

Results .................................................................................. 12

Discussion ............................................................................ 16

II. Landscape effects on carnivore occupancy in the Appalachian
Trail corridor ................................................................. 25

Abstract ................................................................................ 25

Introduction ......................................................................... 26

Methods ................................................................................ 28

Results .................................................................................. 34

Discussion ............................................................................ 36

BIBLIOGRAPHY ........................................................................................ 42
viii

TABLES

Table

1.1 Covariates for occupancy and detection probabilities…………..…11

1.2 Species detection rates ................................................................... 12

1.3 Top logistic models for predicting the occupancy of eight
mammal species ........................................................................ 13

1.4 The summed model weight and direction of influence for
each occupancy covariate in Table 1. ....................................... 14

2.1 Covariates for occupancy and detection probabilities…………..…31

2.2 Top logistic models for predicting the occupancy of five
carnivore species ...................................................................... 34

2.3 Top landscape structure models predicting the occupancy of
five carnivore species in the absence of available forest ......... 39
ix

FIGURES

Figure

1.1 Map of study area and distribution of survey sites along the
Appalachian Trail. ...................................................................... 6

1.2 Mean and standard error of estimated occupancy in hunting
vs. non-hunting areas for black bear, bobcat, and
white-tailed deer ....................................................................... 19

1.3 Mean and standard error of estimated occupancy in low vs.
high trail use areas for black bear and red fox ........................ 21

1.4 Estimated occupancy as a function of distance from road for
white-tailed deer ....................................................................... 22