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This is to certify that the

dissertation entitled

Effects of Human Activities on Birds
Across Landscapes in the Midwest

presented by

Christopher Andrew Lepczyk

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Ecol. & Evol. Bio.
Behavior Program

 

 

 

 

 

 

 

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EFFECTS OF HUMAN ACTIVITIES ON BIRDS ACROSS
LANDSCAPES IN THE MIDWEST

By

Christopher Andrew Lepczyk

A DISSERTATION

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY

Department of Fisheries and Wildlife
Program in Ecology, Evolutionary Biology, and Behavior

2002

ABSTRACT

EFFECTS OF HUMAN ACTIVITIES ON BIRDS ACROSS
LANDSCAPES IN THE MIDWEST

By

Christopher Andrew Lepczyk

Fluctuations of bird abundances in the Midwestern US. have been attributed to
such factors as supplemental feeding, landscape change, habitat fragmentation, and
depredation. A common underlying aspect of these and other factors that may be
responsible for influencing bird abundances is the role of private landowners that live in
the landscapes being investigated. Because private landowners are the ultimate
controllers of their land, they may be carrying out a variety of actions that could, if taken
cumulatively across large areas and over time, influence bird abundances and
distributions. Taking an interdisciplinary approach towards understanding the role of
private landowners on birds, the main objectives of the study were to: 1) Discern the role
of landowners’ activities and perceptions towards birds on a selected group of three
landscapes; 2) Test for differences in activities and perceptions across the rural-to-urban
gradient comprising the three landscapes; 3) aggregate results to the landscape level and,
4) Examine if the relative abundance and diversity of bird species across landscapes was
related to landowner activities and human influences.

To address objectives 1 through 3 I surveyed all ~1,7OO private landowners living
in three landscapes in Southeastern Michigan, where >90% of land is privately owned.
The three landscapes represent urban, suburban, and rural landscapes based on their
geographic locations, average land parcel sizes, and socio-demographic compositions.

For the final objective I analyzed 402 landscapes across the entire Midwest.

Of the 969 landowners that responded (58.5% response rate), 920 (95%) carried
out at least one activity (of eight measured) on their land that can have a potential impact
on birds, with the average landowner carrying out four. Collectively, 66% of landowners
fed birds, 46% provided bird houses, 26% had outdoor cats, 55% planted or maintained
vegetation explicitly for birds, 49% applied fertilizer, 73% gardened, 72% landscaped,
and 25% applied pesticides or herbicides. The number/landowner of bird feeders, bird
houses, and outdoor cats was greatest in the rural landscape and least in the urban.
However, densities (#/ha) of feeders, houses, and cats showed an inverse trend, with the
greatest densities occurring in the urban landscape. In terms of perceptions, the typical
landowner indicated that the number of birds had increased over time and that having bird
diversity on their property was very important, but that they were only slightly willing to
change their land use for the benefit of birds. Across the three landscapes there were
significant differences in both the proportion and the magnitude of landowner activities as
well as landowner perceptions towards birds. Aggregating all landowners across the
landscapes indicates that a minimum of 25% to 40% of the landowners were involved in
each of the eight activities.

Across all Midwest landscapes there was a negative relationship between avian
diversity and (l) the number of housing units and (2) the amount of anthropogenic land
cover. Most bird species investigated displayed significant relationships with the level of
human influence on the landscape. However no relationships existed based on the natural
history classifications of diet and nest. Overall, the results reinforce the need to include
human activities in the conservation, management, and research of birds across
landscapes, while at the same time providing a significant contribution towards the

integration of socioeconomic and ecological research.

Copyright by
CHRISTOPHER ANDREW LEPCZYK
2002

In memory of Eric Wynn Cox (1969-1999), wildlife ecologist, naturalist, and fiiend.

PREFACE

The research which comprises this dissertation is the culmination of nearly six
years of work, thought, and discussions about how people, wildlife, socioeconomics, and
landscape ecology, are all interrelated. During this time I explored many avenues of
inquiry, seeking to better understand how people influence the world around them. As
with all research, some of these avenues were dead ends, while others were a bounty of
reward. By the end of my studies all of these avenues had not only provided me with
many new perspectives, but had provided many new and unique opportunities, which I
feel extremely fortunate to have partaken in while here at Michigan State University.

In many ways a dissertation can be likened to standing on the shoulders of giants.
The work and research which I undertook could not have been completed without
countless years of ecological research prior to my endeavors, nor could it have been
completed without the assistance of a great many people. First of all, I would like to
extend my gratitude to all of the administrative staff both in the Department of Fisheries
and Wildlife and in the Program for Ecology, Evolutionary Biology, and Behavior. In
particular I am especially grateful to Jane Thompson, Julie Traver, Jim Brown, and Pat
Ressler. Without the assistance of Jane and Julie the entire process could not have run so
smoothly. I would also like to extend my thanks to Dan Brown, Kay Gross, Nan Johnson,
and Pat Soranno, who served as members of my doctoral committee. These four
individuals provided critical feedback on my work and offered many interesting insights

on the research, for which I am thankful. One additional individual who served as an

vi

unofficial committee member (i.e., the fifth Beetle if you will) and statistical consultant
was Angela Mertig. Aside from her coauthor duties, Angie spent a great deal of time
discussing research, the philosophy of science, and what it means to lead a collegial and
intellectual life, which all too often are missing from the formal graduate education. Of
course, little could have been accomplished without the assistance of my major advisor,
Jianguo (Jack) Liu. Many years ago Jack took a chance by allowing me to switch from
my previous research track in physiological ecology to landscape ecology. Not only did
Jack allow me to pursue new directions, but he has always provided many unique
opportunities to interact with colleagues and attend a number of scientific meetings.
Finally, Jack provided a completely different view of research and academics than my
previous experiences, which has helped to shape my thinking about teaching, research,
and academics as a whole.

Two peOple that deserve particular mention during my years at MSU are Daniel
Rutledge and Marc Linderman. When I first arrived at MSU I would scarcely have
believed that Daniel would be one of the most important people I would meet. Not only
was Daniel a great friend and weight lifting partner, but he was one of the most creative
and insightful scientists I met in graduate school (or elsewhere). I look forward to many
years of interesting work and friendship beyond those spent at MSU. Similarly, Marc
was more help than he’ll ever know in regards to remote sensing and GIS questions. But
it was Marc’s wide interests and desire for intellectual discourse that I appreciated most.
To Daniel and Marc, thanks for the many years of great discussions and your friendship.

One person who arrived late in my tenure at MSU, but helped see me through the

end of my dissertation was Rebecca Christoffel. Rebecca has been a great friend since I

vii

met her as a Masters student at the University of Wisconsin and is one of the sharpest
naturalist and broadest thinkers I met during that time. Thanks for everything all of these
years!

Over the course of my time in Jack’s lab there were many other graduate students,
faculty members, and labmates that deserve specific mention. These people were not just
colleagues, but many were good fiiends. In Jack’s lab these people included Li An,
Amanda McDonald, Ed Laurent, Jialong Xie, Kiersten Kress, Scott Bearer, Kim Hall,
and Anita Morzillo. Others in both the Fisheries and Wildlife Department and the EEBB
program include Robert Holsman, Peter Bull, Sam Riffell, Paul Keenlance, Joe Gathman,
Kristen Genet, Laura Granack, Meera Iyer, Rich Kobe, and Mike Walters.

The research in this dissertation could not have been accomplished without the
many hours spent by the undergraduate students in Jack’s laboratory who assisted with
the work. These students include Kimberly Baker, Jayson Egeler, Doug Longpre, and
Jessica Swartz. In addition I would also like to thank the staff at the Ingham, Livingston,
Oakland, and Washtenaw county Equalization Offices, which allowed me access to
landowner records. Finally, Keith Pardieck and Jane Fallon at the USGS Patuxent
Wildlife Research Center kindly assisted with providing maps and details of BBS routes.

I could not have pursued a number of interesting avenues with my research
without the support of a United States Environmental Protection Agency Science To
Achieve Results (STAR) Graduate Fellowship (Grant no. U-91580101-0) and the original
financial contributions provided by a Michigan Agricultural Experiment Station grant and
a Michigan State University College of Social Science Grant to J. Liu, A. Mertig, and P.

Soranno, and an N.S.F. CAREER Award to J. Liu. In addition I wish to acknowledge the

viii

Department ofFisheries and Wildlife Graduate Student Organization, Michigan State
University’s College of Agriculture and Natural Resources, the International Studies
Program at Michigan State University, the Department of Fisheries and Wildlife, the
Graduate School, the American Ornithologists’ Union, and the US. Chapter of the
International Association for Landscape Ecology, all of which provided travel funding
over the years to support the presentation of my research. Specifically these travel funds
supported presentations at: the Ecological Society of America meetings in Baltimore,
MD, and Madison, WI; the Society for Conservation Biology meeting in Hilo, HI; the
United States Chapter of the International Association for Landscape Ecology meetings in
East Lansing, MI and Lincoln, NE; the United Kingdom Chapter of the International
Association for Landscape Ecology meeting in Norwich, England; and the American
Omithologists’ Union meetings in Minneapolis, MN, and New Orleans, LA.

Beyond those individuals directly involved in my doctoral research, I owe a great
debt of gratitude to many teachers, professors, and colleagues that I met over the years
who helped shape my thinking and views. These people include Boyd Wilson, Ed
Hansen, Al Kniss, Peter Arcese, Scott McWilliams, Bill Karasov, Greg and Kathy
Murray, and Eugene Odum. In each of your own ways you helped to foster my
intellectual development and curiosity.

In closing there remains one final group of individuals to whom I count on for
their love, support, and friendship. First, my wife Jean, who has provided a listening ear
when I have a down day, has been ceaseless in her endeavors to educate me about birds.
animals, and plants, and has given more of herself over the years than I can ever repay.

Second, to my brothers Peter and Tim, whom I can always count on for an evening of

ix

laughter, merriment, and conversation. While we have grown older and closer, my
fondest memories are still of the summers that the three of us spent at Culhane Lake. To
my mother, who has been a source of intellectual inspiration and a pillar of support. If it
were not for you putting Tim, Peter, and I first, I doubt I would ever have made it this far.
I also owe a great deal of gratitude to my extended family, especially Lorna and Joel.
Lastly, I would never have pursued the direction I did in life without such great mentors
as Greg and Kathy Murray. To you both, all I can say is thanks for the years of support

and friendship.

TABLE OF CONTENTS

LIST OF TABLES ............................................................................................................... xii
LIST OF FIGURES ............................................................................................................. xiv
INTRODUCTION ................................................................................................................. 1
CHAPTER 1
LANDOWNERS AND CAT PREDATION ACROSS RURAL-TO-URBAN
LANDSCAPES .................................................................................................................... 7
Abstract ........................................................................................................................... 8
Introduction ..................................................................................................................... 9
Methods ......................................................................................................................... 13
Results ........................................................................................................................... l 9
Discussion ..................................................................................................................... 22
Acknowledgments ......................................................................................................... 28
References ...................................................................................................................... 29
Figure Legends .............................................................................................................. 41
CHAPTER 2
ASSESSING LANDOWNER ACTIVITIES THAT INFLUENCE BIRDS
ACROSS RURAL-TO-URBAN LANDSCAPES ............................................................... 45
Abstract ......................................................................................................................... 46
Introduction .................................................................................................................... 48
Methods ......................................................................................................................... 53
Results ........................................................................................................................... 59
Landowner Socio-demographic Composition .......................................................... 59
Landowner Activities ............................................................................................... 60
Correspondence Between Activities ........................................................................ 63
Comparison of Landowners Participating in Activities Versus
Non-Participants ...................................................................................................... 63
Discussion ..................................................................................................................... 69
Specific Activities ................................................................................................... 70
Differences in Activities Across Landscapes ............................................................ 75
Hypotheses Tested ................................................................................................... 77
Comparison of Landowners Participating in Activities versus Nonparticipants....78
Conclusion .............................................................................................................. 78
Acknowledgments ......................................................................................................... 79
Literature Cited .............................................................................................................. 80
Figure Legends .............................................................................................................. 97

xi

CHAPTER 3
LANDOWNER PERCEPTIONS AND ACTIVITIES RELATED TO BIRDS

ACROSS RURAL-TO-URBAN LANDSCAPES ............................................................. 105
Abstract ....................................................................................................................... 106
Introduction ................................................................................................................... l 08
Methods ....................................................................................................................... l 10
Results ......................................................................................................................... 1 13
Discussion ................................................................................................................... 1 16
Acknowledgments ....................................................................................................... 1 19
References ..................................................................................................................... 1 19
Figure Legends ............................................................................................................ 123

CHAPTER 4

BIRD DIVERSITY ACROSS A LANDSCAPE: INTEGRATING AND

COMPARING PUBLISHED DATA WITH LANDOWNER OBSERVATIONS .............. 126
Abstract ....................................................................................................................... 127
Introduction ................................................................................................................. 1 28
Methods ....................................................................................................................... 129
Results ......................................................................................................................... 132
Discussion ................................................................................................................... 133
Acknowledgments ....................................................................................................... l 3 5
Literature Cited ............................................................................................................ 136

CHAPTER 5

THE HUMAN INFLUENCE ON BIRDS ACROSS LANDSCAPES ................................ 157
Abstract ....................................................................................................................... 1 5 8
Introduction ................................................................................................................. 1 60
Methods ....................................................................................................................... 164

Breeding Bird Survey ............................................................................................. 164
Species Selection ................................................................................................... 165
Land Cover and Housing Data ................................................................................ 165
Landscape Analysis .............................................................................................. 166
Statistical Analysis of Breeding Bird Data Across the Landscapes ..................... 167
Results ......................................................................................................................... 169
Discussion ................................................................................................................... 171
Acknowledgments ....................................................................................................... 1 75
Literature Cited ........................................................................................................... 176
Figure Legends ............................................................................................................ 188

SYNTHESIS AND CONCLUSIONS ................................................................................ 194

APPENDIX A

LANDOWNER SURVEY ................................................................................................. 201

xii

APPENDIX B

EXAMPLE OF SURVEY COVER LETTER TO LANDOWNER ..................................... 210
APPENDIX C
POST CARD NOTIFICATION TO LANDOWNER ......................................................... 212
APPENDIX D
EXAMPLE OF SECOND SURVEY COVER LETTER TO LANDOWNER .................... 214
BIBLIOGRAPHY ............................................................................................................. 216

xiii

Table 1.1

Table 1.2

Table 1.3

Table 1.4

Table 1.5

Table 2.1

Table 2.2

Table 2.3

Table 2.4

Table 2.5

Table 2.6

Table 2.7

Table 2.8

Table 3.1

Table 3.2

Table 4.1

Table 4.2

LIST OF TABLES

Summary information for free-ranging cat owners by landscape ............... 35
Predation rates for free-ranging cat owners by landscape ........................... 36
Landscape level results of the proportional range of landowners

allowing cats outdoors, the number of possible cats that are

predatory, the density per linear kilometer of predatory cats, and

the total number of birds killed under differing estimation procedures ...... 37

Bird species reported to be depredated by outdoor cats and the

number of different respondents identifying each species .......................... 39
Age and education of free-ranging cat owners by landscape ...................... 40
Summary statistics of socio-demographic information by landscape ......... 89
Occupations of respondents by landscape .................................................. 90
Time engaged in providing bird feed and houses by landscape ................. 91

Number of landowners in each landscape that planted specific types
of vegetation ................................................................................................ 92

Number and percent of landowners involved in gardening,
landscaping, fertilizing, and applying herbicides or pesticides ................... 93

Percent of landowners that carried out each activity in combination ......... 94

Minimum and maximum percent of landowners across all
landscapes engaged in each activity .............................................................. 95

Comparison of landowners involved in a given activity versus those

not involved based upon selected socio-demographic factors ..................... 96
Landowner perceptions and attitudes across landscapes .......................... 121
Percent of landowners involved in each activity across landscapes ......... 122
All possible species, as denoted by different survey methods .................. 138
Comparison of all surveys with all possible combinations ....................... 156

xiv

Table 5.1

Table 5.2

Table 5.3

Table 5.4

Table 5.5

Table 5.6

Table 5.7

Bird species selected for population trend analysis .................................. 181
NLCD land cover classes .......................................................................... 182

Descriptive statistics of anthropogenic land cover and housing in
the landscapes encompassing the 402 BBS routes ....................................... l 83

Regression analysis of proportion of individuals occupying a
landscape relative to the total number of housing units ................................ l 84

Regression analysis of proportion of individuals occupying a
landscape relative to total amount of anthropogenic land cover ............... 185

Multiple regression analysis of proportion of individuals occupying
a landscape relative to both the total amount of anthropogenic land

cover and the total number of housing units ................................................. 1 86

Route-regression analyses of all BBS routes across the Midwest
region ......................................................................................................... 187

XV

Figure 1.1

Figure 1.2

Figure 1.3

Figure 2.1

Figure 2.2

Figure 2.3

Figure 2.4

Figure 2.5

Figure 2.6

Figure 2.7

Figure 3.1

Figure 3.2

Figure 5.1

Figure 5.2

Figure 5.3

LIST OF FIGURES

Location of the three study landscapes in Southeastern Michigan ............. 42

Frequency distribution of the number of cats reported to be allowed
outdoors per landowner .............................................................................. 43

Number of bird feeders per landowner versus number of birds
depredated per week per cat ........................................................................... 44

Location of the three study landscapes in Southeastern Michigan ............. 98

Frequency distribution of the number of bird feeders per landowner
for landowners that fed birds ...................................................................... 99

Number (A) and density (B) of bird feeders across the three
landscapes among landowners that fed birds ............................................... 1 00

Number of landowners feeding birds each month ........................................ 101

Frequency distribution of the number of bird houses per landowner
for landowners that had bird houses ............................................................ 1 02

Number (A) and density (B) of bird houses across the three different
landscapes among landowners that had bird houses .................................... l 03

Number of activities each landowner is engaged in versus the
number of respondents ............................................................................... l 04

Locations of the three landscapes (each 39.4 km) in southeast
Michigan, USA, where the survey was conducted ....................................... 124

The importance of bird diversity versus the number of activities
landowners engage in ................................................................................. 125

Locations of all 402 Breeding Bird Survey (BBS) routes across the

Midwest United States .............................................................................. 189
Total bird diversity (# of species) versus the total number of

housing units ............................................................................................. 190
Total bird diversity (# of species) versus anthropogenic land cover ........ 191

xvi

Figure 5.4 Proportion of individuals occupying each landscape versus the

total number of housing units for each of the twelve species ................... 192
Figure 5.5 Proportion of individuals occupying each landscape versus the total
amount of anthropogenic land cover for each of the twelve species ........ 193

xvii

INTRODUCTION

Ecologists have long recognized that human beings directly and indirectly
influence the ecosystems and landscapes that surround them (Leopold 1949, Odum 1959).
However, it was not until the latter portion of the twentieth century that ecologists had
begun to quantify the degree to which humans were influencing the world’s ecosystems

and landscapes (Vitousek et al. 1986, Vitousek et al. 1997, Pimm 2001). With this

increased accounting came an increased awareness that detailed information on how
humans interact and influence the different ecosystems and landscapes was urgently
needed. Because of this need, there has been a substantial increase in interdisciplinary
ecological research that incorporates socioeconomics, human demography, and human
dimensions techniques (Liu 2001), as well as designating long-term ecological research
sites in urban locations (Parlange 1998) to understand the interrelationship between
humans and landscapes. This dissertation is one such attempt to add a piece of
knowledge towards our understanding of how humans influence landscapes.
Throughout the world, one group of species that has experienced a host of
responses to human influences across a multitude of ecosystems and landscapes is birds.
From extinction (Pimm 2001 ), to population increases, to slow population declines,
nearly all bird species displaying these phenomena have some relationship to human
influence. Within the United States bird populations have experienced marked declines
and fluctuations during the past 30 years. In fact, current estimates indicate that over
25% (204) of the bird species in the United States have declining populations (Audubon

2002). These population declines have been attributed to a host of interrelated factors,

including habitat fragmentation and loss (Robbins et al. 1989, F ahrig 1997, Askins 2000,
Donovan and Flather 2002), nest predation (see Heske et al. 2001 for review), cowbird
parasitization (Robinson et al. 1995), and increased mortality on their wintering-grounds
(Rappole and McDonald 1994, Basili and Temple 1999). However, while many bird
species are experiencing population declines, a number of other bird species are
displaying large population increases. For instance, in Michigan the American Crow
(Corvus brachyrhvnchos) has been exhibiting a significant increase of nearly 2% per year
over the past twenty years (Sauer et al. 2001). Along similar lines of reasoning for
population declines, there are a number of interrelated factors responsible for these
increases, including supplemental feeding and housing (Brittingham and Temple 1988,
Doherty and Grubb 2002), and increased amount of edge habitat. Although both
population increases and decreases have been attributed to a wide number of proximate
causes, in most cases the underlying ultimate influence is humans.

Although more than 65% of the land in the United States (Dale et al. 2000), and
90% in Southern Michigan, is in private ownership, one overlooked cause of human
influence on birds and their ecosystems is the private landowner. More specifically,
because private landowners are the ultimate controllers of their land, they may be carrying
out a wide variety of actions that could, if taken cumulatively across large areas, either
positively or negatively influence bird abundances and distributions. Hence, the major
goal of this dissertation was to begin to address how landowners influence birds through
their activities across landscapes and to utilize the findings to make predictions about bird
species across different landscapes. To investigate this goal, the primary objectives of the

research were to:

l) Discem the role of landowners’ activities and perceptions towards birds on a
selected group of three landscapes;

2) Test for differences in activities and perceptions across the rural-to-urban
gradient comprising the three landscapes;

3) Aggregate landowner activity results to the landscape level; and,

4) Examine if the relative abundance and diversity of bird species across

landscapes was related to landowner activities and human influences.

These four primary objectives are addressed through a total of five chapters
focusing on Southeast Michigan and the entire Midwest that compose this dissertation.
The first four chapters are based on an in-depth survey (Appendix A) administered to
100% (~1,700 people) of the private landowners on three North American Breeding Bird
Survey routes in Southeast Michigan that can be classified as rural, suburban, and urban
landscapes, respectively. The final chapter of this dissertation attempts to utilize the three
commonly engaged in activities of feeding birds, providing bird houses, and allowing
house cats outdoors, as found in Chapters One and Two, in order to make general
predictions about bird abundance and diversity across 402 landscapes surrounding
Breeding Bird Survey routes of eight Midwest states.

The first chapter (Chapter One) focuses on the landowner activity of allowing
house cats (figs gains) outdoors and its potential influence on birds. While house cats
are widely recognized as a conservation threat to birds, as indicated by several classic
articles (Churcher and Lawton 1987, Coleman and Temple 1993), there has been little

effort to investigate how they are spread across landscapes or how they relate to socio-

demographic factors. Hence, the objective of Chapter One is to both quantify aspects of
outdoor house cats and relate them to landowner characteristics.

Chapter Two moves beyond the activity of allowing house cats outdoors to
investigate seven additional landowner activities that have been described or implicated
in the literature as having an influence on bird abundances and populations. These seven
additional activities include providing bird food, providing bird houses, planting and
maintaining vegetation for the benefit of birds, gardening, landscaping, applying
fertilizer, and applying pesticides or herbicides. The objective of Chapter Two is to
quantify the level of participation of these seven activities in order to understand general
landowner behavior that can influence birds across landscapes.

The focus of Chapter Three is how the eight landowner activities measured in
Chapters One and Two are related to landowner perceptions of birds on their land.
Specifically, landowner activities were classified as positive or negative based on a priori
expectations and then related to five measures of how landowners perceive birds on their
land and their willingness to change their behavior for the benefit of birds. The specific
landowner perceptions that were investigated include the View that bird numbers have
changed over time, the importance of bird diversity, the number of birds living in the
vicinity of the property, interest in tax easements or abatements in exchange for
preserving bird habitat, and willingness to alter one’s land use for the benefit of birds.
Thus, the objective of Chapter Three was both to quantify landowner perceptions and
relate them to how many positive and negative activities the landowners were engaged in
on their property.

The objective of Chapter Four is to describe all bird species observed by

landowners in comparison to other published sources in order to compose a complete bird
list for the study area. Because landowners have the ability to see many species on their
property which scientists and managers do not, they may provide different estimates of
how many species frequent a landscape.

Finally, Chapter Five investigate how bird diversity and the relative abundance of
selected bird species relates to two measures of human influence, the number of housing
units present on the landscape and the total amount of anthropogenic land cover, across
402 landscapes encompassing Breeding Bird Survey routes of the Midwest. In addition,
the chapter investigates how two important natural history characteristics, diet type and
nest location, are related to the relative abundance across landscapes. These two natural
history categories were selected based on the results of landowner activities found in
Chapters One and Two. Specifically, food and nest supplementation as well as the
presence of outdoor house cats were found to occur at high frequencies across all three
landscapes in Southeast Michigan, suggesting that they could differentially influence
birds based on their major diet and nest types. Thus, the final chapter represents a first
attempt to integrate specific landowner activities from a subset of landscapes in order to
make general predictions at a larger scale.

Each of the five chapters is written in a slightly different style, dependent upon
where they have been or will be submitted for publication. Specifically, Chapter One is
written in the style of Biological Conservation, where it is currently in revision and is
expected to be accepted and published in 2003; Chapter Two is written in general journal
article format and will be submitted to an appropriate journal, such as Environmental

Management, following acceptance of the dissertation; Chapter Three has been published

as a conference proceedings (Lepczyk et al. 2002) for the 2002 United Kingdom-
International Association for Landscape Ecology meeting held in Norwhich England;
Chapter Four is written in the style of the Journal of Field Ornithology, where it will be
submitted as a field note following acceptance of the dissertation; and, Chapter Five is
written in the style of Ecological Applications, where it will be submitted upon the
addition of further data analyses. Contributing to the chapters are a variety of coauthors,
which include Dr. Jianguo Liu (Chapters 1, 2, 3, and 5), Dr. Angela Mertig (Chapters 1,

2, and 3), Dr. Volker Radeloff (Chapter 5). and Dr. Curtis Flahter (Chapter 5).

CHAPTER 1

LANDOWNERS AND CAT PREDATION ACROSS

RURAL-TO-URBAN LANDSCAPES

ABSTRACT

Fluctuations of bird abundances have been attributed to such factors as supplemental
feeding, landscape change, and habitat fragmentation. Notably absent from
consideration, however, is the role of private landowners and their actions, such as
owning free-ranging domestic cats Llfiig c_at_u§; cats allowed free access to the outdoors).
To understand the impacts of cat predation on birds, we surveyed all 1,694 private
landowners living on three breeding bird survey (BBS) routes (~120 km) that represent a
continuum of rural-to-urban landscapes in Southeastern Michigan, where the majority
(>90%) of land is privately owned. Our data indicate that among the 58.5% of
landowners that responded, one quarter of them owned outdoor cats. On average a cat
depredated between 0.7 and 1.4 birds per week. A total of 23+ species (12.5% of breeding
species) were on the list of being killed, including two species of conservation concern
(Eastern Bluebirds and Ruby-throated Hummingbirds). Across the three landscapes there
were ~800 to ~3,100 cats, which kill between ~16,000 to ~47,000 birds during the
breeding season, resulting in a minimum of ~1 bird killed/km/day. While the number
and density (#/ha) of free-ranging cats per landowner differed across the rural to urban
landscapes, depredation rates were similar. Landowner participation in bird feeding
showed no relationship with the number of free—ranging cats owned. Similarly, selected
demographic characteristics of landowners were not significantly related to the number of
free-ranging cats owned. Our results, even taken conservatively, indicate that cat
predation plays an important role in fluctuations of bird populations and should receive

more attention in wildlife conservation and landscape studies.

INTRODUCTION

Since the mid 19603, long-term data on breeding birds have indicated that many
species are declining or fluctuating throughout the Midwest and Eastern United States
(Robbins et al. 1989, Terborgh 1989). These declines and fluctuations have been
attributed to factors such as habitat fragmentation and destruction (Robbins et al. 1989.
Donovan and Flather 2002), landscape change (Flather & Sauer 1996), and direct
mortality due to events (e.g., culling by farmers) on the wintering-grounds of the
neotropics (Rappole & McDonald 1994, Basili & Temple 1999). Largely absent from
consideration in the potential mechanisms responsible for influencing breeding bird
abundances are the landowners that live in the landscapes being investigated. Because
private landowners are the ultimate controllers of their land, they may be carrying out a
wide variety of actions that could influence bird abundances and distributions. Their
cumulative and collective effects across large areas and over time may be even more
drastic. Furthermore, landowners living in rural landscapes may carry out activities at
different levels than those in urban landscapes. Such differences may in part explain the
substantial variations in bird abundances and diversity often noted along urban to rural
gradients or in urban contexts (e.g., Emlen 1974, Hohtola 1978, Cam et al. 2000).

Because of the potential for significant landowner effects on birds, there has been
increased attention directed towards the integration of social and economic components
into questions of avian distributions (Hostetler 1999). However, until recently ecologists
have largely ignored the human components in ecological research (Lubchenco et al.

1991, Gallagher & Carpenter 1997, Vitousek et al., 1997, Liu 2001). As a result,

ecologists’ understanding of how humans interact with and influence different
ecosystems, and the species they contain, is still in its early stage (Redman 1999). To
move beyond this basic level, ecologists are increasingly incorporating socioeconomics,
human demography, and social science techniques, such as social surveys, to understand
the interrelationship between humans and the ecosystems within which they live (Turner
et al. 1996, Liu et al. 1999, Liu et al. 2001). As human behaviors are the direct force
affecting ecosystems, it is essential to incorporate human behaviors into the
understanding of ecological patterns such as abundance and diversity of bird species.
One specific behavior that could negatively impact breeding birds is allowing
domestic cats (@ ms) free access to the outdoors. Although free-ranging domestic
cats (i.e., house cats that have free access to the outdoors; a.k.a. outdoor cats)
predominantly depredate small mammals (Fitzgerald & Turner 2000), birds constitute a
large secondary source of prey (Coman & Brunner 1972, Pearre & Maass 1998). While
the fact that cats prey upon birds is unquestioned, the degree to which they negatively
impact bird populations (or any prey species) has been a point of contention in the
literature (Barratt 1998). Because domestic cats have coexisted with humans for
centuries, Fitzgerald & Turner (2000) argue that any continental population of birds that
could not withstand predation by cats would have been extirpated long ago. Another
perspective holds that cats are simply occupying the role of a natural predator. That is.
cats are assumed to fill a role similar to that of species such as raccoons (Procvon lotor),
skunks (Mephitis mephitis), and raptors. A final point that has been made is that people
simply observe avian depredation by cats more than other natural phenomena because it

takes place during the day time and often close to the house, which results in the

10

assumption that cats are reducing bird populations (see Patronek 1998 for details).

Countering the previous points is the fact that domestic cats are subsidized
predators and are thus likely to have a larger total effect on bird species. Specifically,
humans provide domestic cats a level of maintenance that other predators do not receive
(Coleman & Temple 1993). As a result they may exist in higher densities and exert a
greater predatory effect than natural predators. Second, cats are opportunistic predators
(Coman & Brunner 1972), both in terms of time and habitat location (Barratt 1997),
meaning they will depredate a prey item if they encounter it. Third, in many human-
dominated landscapes where top-level predators are absent, domestic cats may be
extolling an even larger predatory effect due to a mesopredator release effect (Crooks &
Soule’ 1999, Risbey et al. 2000). The mesopredator release effect is simply the situation
in which top level predators have either been greatly reduced or extirpated, resulting in an
increase of second-tier predators, such as skunks, raccoons, and domestic cats. Fourth.
cats often depredate birds more during the breeding months when nestlings and fledglings
are bountiful (Eberhard 1954, Dunn & Tessaglia 1994). Fifth, cats may be directly
competing with avian predators, such as American Kestrels (Falco sparverius), Northern
Harriers (Circus cvaneus) and Red-tailed Hawks (Buteo jamaicensis; George 1974).
Finally, even very low cat depredation could negatively impact the breeding success and
viability of a species (Crooks & Soule’ 1999).

As part of a larger effort to understand and integrate the social and ecological
factors influencing breeding bird abundances among different rural to urban landscapes
(Lepczyk et al. 2002, Chapters 2 and 3), we sought to address the roles of free-ranging

cats and the landowners that own them. Specifically, we were interested in ascertaining:

ll

l) the proportion of landowners that allow their cats outside; 2) the number and density
(cats/ha) of cats each household owned that were allowed access to the outside; 3) how
many dead or injured birds a week the cats brought in during the breeding season (i.e.,
April through August); 4) what cat predation rates were at the landscape level; 5) what
bird species were brought home by the cats; and, 6) if differences existed across a rural to
urban gradient.

Aside from understanding the six aforementioned issues, we also tested three a
priori hypotheses. Our first hypothesis was that because bird feeders may act to magnify
local bird densities, a relationship would exist between both the number and density of
bird feeders and cat depredation rates. We predicted that as the number and/or density of
bird feeders increased there would be a related increase in the number of birds depredated
per cat. In addition, because the role of domestic cats as predators has received wide-
spread attention among academic and professional organizations (Cooper Ornithological
Society’s resolution on Public Policies Regarding Feral and Free-ranging Cats
[http://cooper.org/cos/67thResolutions.htm] and American Bird Conservancy’s
Resolution on house cats [http://www.abcbirds.org/cats/Resolution.PDF]), non-academic
venues (e.g., National Audubon Society Resolution on Cats
[http://www.audubon.org/local/cn/98march/cats.html; Wisconsin Natural Resources
Magazine [http://www.wnrmag.com/stories/ 1996/dec96/cats.htm (1996), veterinarians,
and non-profit educational programs (e. g., American Bird Conservancy’s Cats Indoors!
[http://www.abcbirds.org/cats/catsindoors.htm), we also sought to integrate our results
with demographic parameters of the landowners to test two other hypotheses.

Specifically, we hypothesized that the number of free—ranging cats would be a function of

12

a landowner’s age and educational level. In the case of a landowner’s age we predicted a
positive relationship between age and number of free-ranging cats they would own, since
the impetus to keep cats indoors has been a relatively recent phenomenon that likely
influences younger landowners more than older landowners. Likewise, we predicted a
negative relationship between education and free-ranging cats, such that the more
education a landowner had the fewer free-ranging cats they would own. We based this
prediction on the grounds that many public and private organizations as well as
veterinarians have strongly advocated keeping cats indoors and that the more education a

landowner has the greater the chance that they have been exposed to such a message.

METHODS

To address the research questions, test our hypotheses, and match the scale of
study areas with locations where long-term data on bird abundance and distribution have
been collected (Vogt et al. 2002), we used three breeding bird survey (BBS) routes (route
numbers 53, 167, and 168) in Southeastern Michigan, United States (Figure 1.1), where
>90% of the land is privately owned. We chose these three routes because they represent
a continuum from rural to urban landscapes, based on their geographic locations, average
land parcel sizes, and socio-demographic compositions. Specifically, route 53 (hereafter
termed Rural) is very rural, has a low population density, large land parcels, and is
removed from any large city center or urban location. Route 168 (hereafter termed
Urban) ranges from being very suburban to being urban, has a high population density,

small land parcels, and transects or parallels residential locations and city centers.

13

Finally, route 167 (hereafter termed Suburban) straddles the demographic differences
between routes 53 and 168 by being suburban, has intermediate population density and
land parcel sizes, and runs parallel to (but never intersects) large residential and city
center locations. In addition, all three routes occur in a heterogeneous and human
dominated region that is undergoing rapid urbanization (Rutledge and Lepczyk 2002),
which is representative of many other regions in North America. The last reason for
selecting these three routes is that they remain active BBS routes, monitored annually by
the United States Fish and Wildlife Service, which allows for future evaluations to be
conducted, and hence, comparisons made over time.

To integrate information about human behaviors into the understanding of
landowner impacts on bird abundance, we conducted a social survey of landowners. For
our study, we chose all private landowners who owned property immediately adjacent to
the road along which each of the three BBS routes is run. We identified the landowners
through a combination of driving each route and using county tax records and plat maps.
Utilizing this combined approach we identified a total of 1,694 private landowners (331
on Rural, 390 on Suburban, and 973 on Urban).

We administered a mail survey instrument between October and December of
2000 following the Total Design Method (Dillman 1978, 2000). The survey instrument
and procedures were fully evaluated for ethical appropriateness by the Michigan State
University Committee on Research Involving Human Subjects prior to mailing. To
encourage responses we established a toll-free telephone line for landowners to contact us
with any questions and offered prize drawings as an incentive. Briefly, an initial survey

was mailed during the first week of October 2000 (Appendix A and B). A

14

reminder/thank you postcard was sent out two weeks later (Appendix C). Finally, a
second survey was sent out two weeks after the postcard to those who had not responded
to the prior mailings (Appendix D).

Our sampling framework was designed to capture only private landowners, hence.
any survey returned from a church, business or public land owner that might have
accidentally been included in the initial sample was removed from the study. Similarly,
surveys that were returned as undeliverable by the United States Postal Service (USPS),
where the recipient was deceased, or where different landowners had the same address as
another landowner and were returned as undeliverable by the USPS, were removed from
the sample. Surveys received after December 3 l , 2000 were not included in any analyses.
If landowners owned multiple parcels that were not connected to one another, then they
were asked to complete the survey in relation to only one of the parcels. However, if the
landowner owned multiple parcels that were all contiguous with one another, then they
were asked to fill out the survey in relation to the entire block of land. Surveys that were
returned blank (i.e., not filled out) or contained notes indicating no interest in
participating in the survey were considered a non-response. Similarly, landowners that
called to indicate they were unable or had no desire to participate in the survey were
considered non-respondents. Non-respondents were included in the final corrected
sample size.

To ascertain the impact of free-ranging cats on bird abundance we asked the
following questions in our survey: (1) How many cats does your household own that are
allowed access to the outside? (2) If you or members of your household own cats that are

allowed access to the outside, approximately how many dead or injured birds a week do

15

all the cats bring in during the spring and summer months (April through August) (0, 1, 2-
3, 4-5, 6-7, 8-9, 10-15, 16-20, more than 20)? (3) Can you or anyone in your household
identify any of the bird species brought home by your cat(s) (yes, no, unsure)? (4) Please
list the names of the bird species that your cat(s) has brought home during the spring and
summer months on the lines below. With regard to the number and density of bird feeders
the following questions were asked: (5) Does anyone in your household feed birds on
your property (yes, no)? (6) How many bird feeders do you have on your property? (7)
Approximately how large is your parcel of land? Finally, to ascertain basic demographic
statistics of the landowners we asked the following questions: (8) In what year were you
born? (9) Are you: Male, Female? (10) How many people currently live in your
household? (11) What is the highest level of school completed or degree you have
received (Some school completed, but no high school diploma; High school graduate or
general equivalency diploma; Some college, but no degree; Associates degree in college;
Bachelor’s degree; Master’s, professional, or doctoral degree)? The six educational
choices offered were a condensation of the nine categories used in the United States
Census form that pooled post-baccalaureate degrees together.

In cases where the respondents did not explicitly follow the survey instructions,
we edited the data as follows. For fill-in-the-blank questions that asked for a single
numeric response, we took the arithmetic mean if a respondent put a range. In a single
case a respondent put a question mark for the number of cats allowed access to the
outdoors. Because all subsequent questions that were contingent upon the number of cats
were answered as owning an outdoor cat, we conservatively assumed that the landowner

had at least one cat. However, in cases where landowners had no cats allowed access to

16

the outdoors, but answered questions contingent on the fact that they did own them, we
converted the values to blank (i.e., no data) entries. In the cases where respondents were
asked for only a single response to a categorical question but filled in two blanks, we used
a coin toss to decide the answer. For the bird species brought home by the cats we
corrected all spelling/grammatical mistakes and made the following assumptions based
on colloquial terminology and bird descriptions compared to known species in the
surrounding landscape. Redbirds and red birds were assumed to be Northern Cardinals
(Cardinalis cardinalis). Turtle doves and doves were assumed to be Mourning Doves
(_Z_ei1a_id_a macroura). Honey-sucking birds and hummers were assumed to be Ruby-
throated Hummingbirds (Archilochus coubris), as no other hummingbirds inhabit
Michigan. Canary, yellow canary, wild canary, yellow finch, and golden finch were
assumed to be American Goldfinches (Carduelis tristis). Crackles or crackens were
assumed to be Common Grackles (Ouiscalus quiscula). Red finches and red-breasted
finches were assumed to be Purple Finches (Camodacus p_u_rpureus). Finally, barn
sparrow was changed to Sparrow, even though it is most likely a House Sparrow, because
of the potential for misidentification.

Because of the potential for under-reporting cat depredation (see Discussion), we
initially calculated a predation rate based on all landowners that had outdoor cats, even if
they indicated predation rates of zero (Predation Rate 1, hereafter termed PR1).

However, we also calculated a second predation rate (Predation Rate 2, hereafter termed
PR2) based only on landowners that had outdoor cats for which they reported one or more
birds killed or injured per week. Given the uncertainty related to the number of cats and

their associated predation rates with regard to the non-respondents, we used several

17

different estimates of non-respondent outdoor cat ownership to provide a plausible range
when scaling-up the results to the landscape level. To estimate the total number of birds
depredated over the breeding season in each landscape we considered non-respondents
from three perspectives: (1) non-respondents have the same number of outdoor cats as
respondents, (2) non-respondents have 50% the number of outdoor cats as respondents,
and (3) non-respondents have 150% the number of outdoor cats as respondents. Under
each assumption we applied both rates of predation, such that under Predation Rate 1 the
total number of birds killed over the breeding season = (number of non-respondents) X
(mean number of cats/landowner) >< (weekly predation rate) X (22 weeks) + (number of
birds killed over 22 weeks from respondents). In the case of Predation Rate 2 we
calculated the total number of birds killed over the breeding season = (number of non-
respondents) >< (proportion of landowners that had cats that killed or injured one or more
bird a week) >< (mean number of cats/landowner) >< (weekly predation rate) X (22 weeks)
+ (number of birds killed over 22 weeks from respondents). We estimated the potential
proportion of landowners involved in allowing their cats outdoors across each landscape
by assuming that all non-respondents did not have cats allowed outdoors (minimum
estimate) and then assuming that they all did have cats allowed outdoors (maximum).
Statistical analyses were performed using the multivariate general linear
hypothesis module in SYSTAT 5.03 (Wilkinson 1992). All density measures were
calculated using the parcel sizes reported by the landowners. Response rate and the
proportion of landowners owning outdoor cats across each landscape were compared
using a two-way contingency table with a Pearson Chi-square test statistic. Comparisons

between cat and non-cat owners were carried out using t-tests, while comparisons across

18

landscapes were carried out with AN OVA. Landscape differences were compared using
Tukey’s HSD procedure (Zar 1996). Data are reported as means :t SE (as 100% of the
population was sampled, but only ~59% responded), unless otherwise noted, with a p-
value of 0.05 considered significant.

Of the 1,694 landowners initially identified, 40 were removed from consideration
because they were a business or church, had property outside the sampling region, already
responded based on another parcel of land within the study landscapes, or their address
information was incorrect, thus reducing the corrected population size to 1,654. Among
these 1,654 we received 968 completed surveys, yielding a 58.5% response rate.
Response rates in different landscapes were 64.8% for Rural (212 of 327), 61 .5% for
Suburban (233 of 379), and 55.2% for Urban (523 of 948), which were significantly

different (X2 = 11.11; df= 2; p = 0.0039).

RESULTS

A total of 253 (26.1%) landowners had cats that were allowed access to the
outside. Of these 253 landowners, 71 (33.5%) were in the Rural landscape, 75 (32.2%)
were in the Suburban landscape, and 107 (20.5%) were in the Urban landscape, indicating
a significantly different proportion of respondents due to the lower frequency in the
Urban landscape (X2 = 19.09; df = 2; p = 0.00007). The total number of free-ranging cats
across all landscapes was 656 (Table 1.1), ranging from 1 to 30 per landowner with a
mean of 2.59 d: 0.20 per landowner (Figure 1.2). Overall, the mean number of free-

ranging cats per landowner was significantly different by landscapes (F = 6.175; df = 2,

19

250; p = 0.0024; Table 1.1), but specific landscape differences were only significant
between the Rural and Urban landscapes (p = 0.0013). Similarly, the density of cats
(#/ha) was significantly different by landscape (F = 9.74; df = 2, 239; p = 0.000086), with
the Urban landscape being different from both the Rural (p = 0.00045) and the Suburban
landscapes (p = 0.00086; Table 1.1).

Of the 253 landowners owning outdoor cats, the mean number of birds depredated
per cat per week (PR1) across all landscapes was 0.683 t 0.12 (n = 245) and were similar
among all landscapes (F = 0.213; df = 2, 242; p = 0.808; Table 1.2). Recalculating
predation rates based only on landowners that had outdoor cats (PR2) for which they
reported one or more birds killed or injured per week reduced the sample size to 118
(Table 1.2). Of these 118 landowners, the mean number of birds depredated per cat per
week (PR2) across all landscapes was 1.42 i 0.22 (Table 1.2). As with PR1 above, PR2
was similar among all three landscapes (F = 0.567; df= 2, 115; p = 0.57; Table 1.2).
Based upon PR1 the overall average total number of birds killed per cat during the
breeding season was 15 compared to an overall average of 32 using PR2 (Table 1.2).
Summing each individual cat’s predation rate over the breeding season indicated that the
total number of birds killed across the three landscapes was 3,680 (Table 1.2).
Depredation rates were not correlated with the number of bird feeders located on each
landowner’s property (1*7 = 0.015; p = 0.10; Figure 1.3), and were not influenced by
landscape type (landscape X number of bird feeders; F = 0.281, df = 2, 180; p = 0.756).
Similarly, depredation rates were not correlated with the density (#/ha) of bird feeders (r2
< 0.001 ; p = 0.631). Scaling the proportion of landowners that have outdoor cats to the

landscape level (by incorporating assumptions about non-respondents) indicates that

20

between 15% and 56% of landowners potentially have outdoor cats (Table 1.3). At the
landscape level the total number of predatory outdoor cats ranged from ~800 to ~3,100,
which killed between ~16,000 and ~47,000 birds (Table 1.3).

Of the 118 landowners that reported their cats killing or injuring one or more birds
a week, 75 (63.6%) were able to identify specific species of birds brought home by their
cats. Twenty three unique species of birds or groups of birds were identified by the
landowners (Table 1.4), which is undoubtedly a conservative estimate (see Discussion
section). The species identified in greatest numbers were Sparrows and Blue Jays
(Cyanocitta cristata), while the least common were Dark-eyed (Slate-colored var.) Junco
(Jitter; hyemalis) and the Tufted Titmouse (Baeolophus bicolor; Table 1.4).

In terms of landowner demography, the average age (11 = 241) of the respondents
owning outdoor cats was 51.3 i 0.86 years compared to 50.4 :1: 0.51 years for respondents
not owning outdoor cats (n = 690), indicating no significant difference in age (t = 0.905;
df = 929; p = 0.366). Similarly, there were no differences in age among free-ranging cat
owners across the three landscapes (F = 0.633; df= 2, 238; p = 0.532; Table 1.5). In
addition there was no relationship between respondent’s age and the number of cats
allowed access to the outdoors (r2 < 0.0005; p = 0.925). With regard to educational level
there was a significant difference among free-ranging cat owners across the landscapes (F
= 26.897; df = 2, 238; p < 0.000005; Table 1.5), but not between free-ranging cat owners
and non free-ranging cat owners (F = 1.650; df = 1, 926; p = 0.199) nor was there an
interaction between free-ranging cat ownership and landscape type (F = 0.083; df = 2,
926; p = 0.921). The significant difference in educational level among owners of free-

ranging cats was found to be between Rural and Suburban, and Suburban and Urban

21

landscapes, but not between the Rural and Urban landscapes. Similarly, there was no
relationship between respondent’s educational level and the number of cats allowed

access to the outdoors (r2 < 0.002; p = 0.461).

DISCUSSION

Overall, our results indicate that free-ranging domestic cats depredated a
minimum of 12.5% of the known breeding bird species (based on 23 of ~184), including
two species of conservation concern (Eastern Bluebird and Ruby-throated Hummingbird).
In the case of the Eastern Bluebird, the location of the three landscapes represents an area
of Michigan where the species is rarest and not always identified on bird atlas survey
routes (Brewer et al. 1991). Ruby-throated Hummingbirds are the only species of
hummingbirds that breed in Michigan and are not typically associated with cat predation
given their small body size. Aside from the Eastern Bluebird and Ruby-throated
Hummingbird, the species depredated in our study are concordant with other studies that
most of the birds being taken by cats were ground or low brush feeders (Table 1.4) and
typically associated with bird feeders and suburban landscapes (Mead 1982, Dunn &
Tessaglia 1994, Carss 1995, Barratt 1997). Although the species group of Sparrows
could not be broken down into species, it is very likely that the dominant species
observed was the House Sparrow (Passer domesitcus). Sparrows were also the most
commonly observed depredated species found in England and Australia (Churcher and

Lawton 1987, Barratt 1997).

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Although no extremely rare species or species of state or national concern were
identified by landowners, that does not mean that cats were not preying upon them. In
fact several factors would lend support to the fact that other species are likely being
depredated. First, because only two-thirds of landowners were able to identify the birds
brought home by their cats, it is very probable that other species were taken in the
properties of the remaining one-third of landowners that acknowledged cat depredation.
Second, the ability of respondents to identify birds correctly is unknown. People are most
familiar with common and brightly colored species. Furthermore, most people tend to
use general colloquial terms, such as Sparrows. Because the ability to discern specific
Sparrow species can be very difficult (Sibley 2000) and other sparrows such as the
Chipping Sparrow (Spizella passerina) often occur in residential areas, it is very likely
that the group “Sparrows” in Table 1.4 consisted of at least two to three separate sparrow
species. Thus, there is most certainly a detection bias among the respondents. Third,
respondents only identified birds that were brought home by their cats. Thus, no measure
of what species may have been consumed in the field were recorded. Fourth, cats often
depredate nestlings (Churcher & Lawton 1987, Dunn & Tessaglia 1994), which can be
very difficult to identify, especially if very young or recently hatched. Finally, cats are
opportunistic predators, suggesting that they are likely to prey upon any species that is
present in its territory. As a result of these factors, the observed species and species
groups being depredated are almost certainly an underestimate of the true number of
species. Keeping these points in mind, our estimate of the number of species depredated

should be considered quite conservative.

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At the landscape scale the total number of outdoor cats and the number of birds
killed over the breeding season is quite wide ranging, depending upon the assumptions
regarding non-respondents. Under the assumption that only respondents had outdoor cats,
there were only 656 cats reported (Table 1.1) and 3,680 birds killed over the breeding
season. However, as discussed below, it is unrealistic to assume that non-respondents
had no outdoor cats. Using three different estimates of non-respondent cat numbers
(Table 1.3), along with the two predation rates, yielded an estimate of between ~16,000
and ~47,000 birds killed during the breeding season across the three landscapes.
Considering that the three landscape routes cover ~l20 kilometers (each BBS route is
39.4 km long), even the low estimate of birds killed represents nearly one bird killed per
day per kilometer (16,000 birds / 120 km / 22 weeks / 7 days = 0.87 birds killed per km
per day).

There were several notable differences observed across the three landscapes
selected in this investigation. Specifically, landowners in the urban landscape were
significantly less likely to own free-ranging cats than were landowners in either the rural
or suburban landscape. However, in terms of the number of free-ranging cats per
landowner a steady decline existed from the rural landscape to the urban landscape (Table
1.1), even though only the rural and urban landscape were significantly different from one
another. Landowners in the urban landscape, however, had significantly higher densities
of free-ranging cats (i.e., they had more cats per hectare) than did landowners in either the
rural or suburban landscapes (Table 1.1). This increase in cat densities from rural-to-
urban landscapes is similar to what was recently found by Haskell et al. (2001), where

greater cat densities were associated with greater housing densities in urban landscapes.

24

Ultimately, while predation rates displayed no difference across the landscapes (Table
1.2), the greater number of landowners in the urban landscape, coupled with greater cat
densities, is one of the main reasons for a greater total predatory effect in the urban
landscape (Tables 1.1 and 1.3).

Because cat predation is often witnessed at bird feeders (Dunn & Tessaglia 1994)
and bird feeders can act to magnify bird densities, we had predicted that there would be a
positive correlation between bird feeder number or density and depredation rates.
However, we found no support for this hypothesis. The lack of a relationship may be due
to the fact that there are relatively few landowners that both allow their cats outdoors and
feed birds or that place bird feeders in accessible places for cats. Regardless of the
specific reason(s) why we found no support for our hypothesis, the lack of correlation is
important in that it suggests that bird feeding is not exacerbating predation rates by cats.

Similar to our first hypothesis, we found no relationships between age or
education of the respondents and the number of free-ranging cats owned, indicating that
our last two hypotheses should also be rejected. The fact that age and educational level
show no relationship with the number of cats allowed access to the outdoors is somewhat
troubling. Given the amount of attention being directed toward keeping domestic cats
indoors by private interest groups, veterinarians, public school systems, and professional
scientific organizations, we had predicted a positive effect of age and a negative effect of
education on the number of cats allowed access to the outdoors. Instead we found no
relationship, suggesting that either the information is not reaching the targeted audience.
or that there is a general indifference to the role of cats as predators. One additional

reason may be that people may know not to let cats outdoors, but not act accordingly (i.e.,

25

action does not follow knowledge). The only factor that showed any relationship with the
number of free-ranging cats was household size (i.e., number of people living in a
residence). Although not explicitly tested as an a priori hypothesis, we investigated the
effect of household size simply as a possible demographic factor. The positive
relationship between the number of people living at a residence and the number of cats is
not totally surprising as larger residences are more likely to have children who own pets.
One caveat of our study is that landowners may have underestimated the number of cats
they allow access to the outside. Such a result was found in a similar study of landowners
in Wisconsin (Coleman & Temple 1993). This underestimate may be due to incomplete
knowledge or a desire to positively bias answers that the respondent felt were associated
with negative connotations (Dillman 1978). In addition, we found that a very common
volunteered response among landowners that had no outdoor cats was that either their
neighbors owned outdoor cats or that feral cats were present in the vicinity of their land.
Given the frequency of these responses relative to the number of landowners that reported
owning outdoor cats suggests that at least some landowners under reported or chose not
to report the number of outdoor cats they owned. Thus, just as our estimate of bird
diversity is likely to be conservative, so is our estimate of free-ranging cat density. As a
result, the actual number of free-ranging cats is in all likelihood larger than our estimate.
Besides the potential underestimate of outdoor cats, our study almost certainly
underestimated the predation rate. This underestimate can be attributed to the following
points. First, only 47% of outdoor cat owners indicated that their cat(s) brought home
dead or injured birds. It is improbable that the remaining 53% of landowners’ cats simply

did not prey upon birds. Second, respondents based their cat’s predation rate only on the

26

birds actually brought home or visible to them, thus missing birds killed and/or consumed
in the field. Third, just as with outdoor cat ownership, respondents may have
underestimated the predation rate as they associate it with negative connotations. As a
result, the actual predation rate and hence total number of birds killed are most certainly
underestimates. Even in the face of such underestimates our study demonstrates the
significant impact of outdoor cats on birds.

While we can not specifically conclude that cats are depredating rare or threatened
species in the three landscapes, there is a strong likelihood that they are impacting some
species of concern. The fact that both Eastern Bluebirds and Ruby-throated
Hummingbirds were listed indicates that some species of concern are being captured.
Furthermore, given the opportunistic predatory nature of cats coupled with one third of
respondents’ inability to discern bird species suggests that our finding of 23 species or
groups of birds being depredated by free-ranging cats is a conservative estimate.
Similarly, by incorporating the potential for undercount of cats by respondents and the
lack of any evaluation of feral cats, the number of cats per landowner is also likely to be a
conservative estimate. Given these factors it is noteworthy to point out that a number of
additional bird species that merit special concern are along the three BBS routes and/or in
the surrounding landscape. These species include three listed as special concern in
Michigan [Western Meadowlark (Stumellla M), Hooded Warbler (Wilsonia
93mg), and Prothonotary Warbler (Protonotaria citrea)], one species that is listed as
threatened by the State of Michigan [Yellow-throated Warbler (Dendroica dominica)],
three that the US. Fish and Wildlife Service designated as being of management concern

[Henslow’s Sparrow (Ammodramus henslowii), Cerulean Warbler (Dendroica cerulea),

27

Golden-winged Warbler (Vermivora chgsopterafl, and species that are at the edge of
their range, such as the Dickcissel (Spiza american_a) (Adams et al. 1988, Brewer et al.
1991)]. A number of other special concern, threatened, and endangered bird species
occur within the vicinity of the study areas, but can be considered at lower potential for
free-ranging cat depredation due to either their large body sizes or nesting locations [e.g.,
Red-shouldered Hawk (Buteo lineatus)].

In terms of management and conservation implications, our results, even taken
conservatively, indicate that free-ranging cats are killing a large number and wide range
of bird species. Our results also highlight the fact that there is still an urgent need to
educate landowners and policy makers regarding the negative impacts of free-ranging
cats. Furthermore, our study illustrates how important private landowners are in
influencing the ecosystem around them. Only by incorporating their knowledge,
decisions, and actions into ecological research can ecologists fully understand the

complex nature of populations and ecosystems on the landscape.

ACKNOWLEDGMENTS

We would like to thank the staff at the Ingham, Livingston, Oakland, and
Washtenaw county Equalization Offices, which allowed us access to landowner records.
Keith Pardieck and Jane Fallon at the USGS Patuxent Wildlife Research Center who
kindly assisted with providing maps and details of BBS routes. We are grateful to
Kimberly Baker, Jayson Egeler and Mike Mascarenhas for assisting with the survey

logistics and data entry. Robert Holsman and Sam Riffell provided critical review of the

28

draft survey. Daniel Brown, Katherine Gross, Nan Johnson, and Patricia Soranno
critically reviewed the manuscript and provided many helpful suggestions. Support for
this research was provided by a Michigan Agricultural Experiment Station grant and an
N.S.F. CAREER Award to J. Liu, a Michigan State University College of Social Science
Grant to J. Liu, A. Mertig, and P. Soranno, and a US. EPA. Science To Achieve Results
(STAR) Fellowship (Grant no. U-91580101-0) to CA. Lepczyk. This paper was
submitted in partial fulfillment of the requirements for CA. Lepczyk’s doctoral degree in
Fisheries and Wildlife, and the Program in Ecology, Evolutionary Biology, and Behavior

at Michigan State University.

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Table 1.4. Bird species reported to be depredated by outdoor cats and the number of

different respondents identifying each species.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bird Species # of Observations
American Goldfinch (Carduelis tristis) 6
American Robin (Turdus migratorius) 12
Barn Swallow (Hirundo rustica) 4
Blackbird‘ 2
Black-capped Chickadee (Poecile atricapilla) 8
Blue Jay (Cvanocitta cristata) 14
Common Grackle (miscalus giscula) 1
Eastern Bluebird (§i_ala my“ 6
European Starling (Sturnus vulgaris) 5
Finch1 3
House Finch (Carpodacus mexicanus) 1
House Sparrow (Passer domesticus) 1
Mourning Dove (m macroura) 6
Northern Cardinal (Cardinalis cardinalis) 2
Nuthatchl 2
Purple Finch (Carpodacus purpureus) 2
Ruby-throated Hummingbird (Archilochus coubris)* 3
Dark-eyed (Slate-colored var.) Junco (J unco hvemalis) 1
Song Sparrow (Melospiza melodia) 1
Sparrowl 51
Swallowl 3
Tufted Titmouse (Baeolophus bicolor) l
Wren' 2

 

' Two or more possible species could be interpreted, thus species level information not
presented.
* Denotes species of conservation concern.

39

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4O

FIGURE LEGENDS

Figure 1.1 Location of the three BBS routes/study landscapes in Southeastern Michigan.
Route 53 is Rural, route 167 is Suburban, and route 168 is Urban. Each BBS route
is 39.8 km in length.

Figure 1.2. Frequency distribution of the number of cats reported to be allowed outdoors
per landowner.

Figure 1.3. Number of bird feeders per landowner versus number of birds depredated per

week per cat.

41

 

 

   
 
 

 
 

it“. s
-. 5g 0 90 I80
3‘ I)‘ \ \KILOMETERS

‘ SUBURBAN

 

42

 

Number of Respondents

125

100

75

50

25

 

 

l

3456789101112152530

Number of Cats per Landowner

43

 

Number of Birds Depredated Per Cat Per Week

15

10

 

 

 

 

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r2=O.015:p=O.1O
o
T _
o
o
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0‘ a
O 5 10 15

Number of Bird Feeders per Landowner

44

CHAPTER 2

ASSESSING LANDOWNER ACTIVITIES THAT INFLUENCE BIRDS

ACROSS RURAL-TO-URBAN LANDSCAPES

45

ABSTRACT

Fluctuations of bird abundances in the Midwest region of the United States have been
attributed to such factors as supplemental feeding, landscape change, habitat
fragmentation, and depredation. However, no attempt has been made to estimate the
collective role of landowner activities on birds across a landscape. To investigate how
landowners might influence birds when the majority (>90%) of land is privately owned,
we surveyed all 1,694 private landowners living on three breeding bird survey (BBS)
routes (~120 km) that represent a continuum of rural-to-urban landscapes in Southeastern
Michigan. Our survey was designed to investigate: 1) the proportion of landowners
involved in bird feeding, providing bird houses, planting or maintaining vegetation for
birds, gardening, landscaping, applying fertilizer, and applying pesticides or herbicides;
2) the magnitude of bird feeders and houses, 3) if differences existed in the activities
across BBS routes; and, 4) if landowners that carried out a given activity were socio-
demographically different from those who did not. Of the 969 respondents (58.6%
response rate), 920 (95%) carried out at least one of the activities on their land and the
average landowner carried out four activities. A total of 65.6% fed birds, 45.7% provided
bird houses, 54.6% planted or maintained vegetation, 72.7% gardened, 72.3% landscaped,
49.3% applied fertilizer, and 25.2% applied pesticides or herbicides. Significant
differences existed among the landscapes as well as between landowners involved in a
given activity versus those not involved in that activity. Scaling the activities to the
landscape level indicates that at least 14% of the landowners are involved in each activity,

and for most activities at least 25%-40% are involved. Taken collectively. our results

46

indicate that landowners are both intentionally and unintentionally engaged in a wide

number of activities that can have profound influences on birds at the landscape scale.

47

INTRODUCTION

The realization that humans modify and create ecosystems and landscapes is not
new (e. g., see Odum 1959). Traditionally, however, this realization was limited to such
systems as agriculture, pasture, orchards, and urban areas (Vitousek et al. 1997). By the
end of the twentieth century such a narrow View of human interaction was eclipsed by the
knowledge that humans were having drastic impacts on all of the world’s ecosystems

(McDonnell and Pickett 1993, Daily 1997, Vitousek et al. 1997). While ecologists now

recognize the scale at which humans influence the global ecology, many have largely
ignored the human component in ecological systems research and instead focused on
natural or pristine systems without humans (Gallagher and Carpenter 1997, Liu 2001).
The consequence of ignoring the human component is that ecologists’ understanding of
how humans interact and influence different ecosystems is still in its early stages
(Redman 1999). Notably, however, ecologists are increasingly incorporating
socioeconomics, human demography, and human dimensions techniques, as well as
designating long-term ecological research sites in urban locations to understand the
interrelationship between humans and the ecosystems within which they live to move
beyond this basic level (Parlange 1998, Liu et al. 1999, Liu et al. 2001).

While incorporating the human component is important for all ecological
research, it is especially pertinent in locations where ecologists have gathered long-term
data on species abundance and distribution (Vogt et al. 2002) because it allows for a more
holistic view of the system being studied and helps to explain the data. Although a wide

variety of long-term data sets exist, one that has been used extensively in ecological

48

research is the North American Breeding Bird Survey (BBS; e.g., Bohning-Gaese et al.
1993, James et al. 1996, Cam et al. 2000). The BBS is a continent wide annual survey

that is conducted along secondary roads randomly located throughout the United States
and Canada. Surveys have been conducted since 1966 on individual routes that are each
39.4 km long. Each route consists of 50 point counts that are 0.8 km apart, where a
competent observer records all birds seen or heard within 0.4 km of the stop (Peterjohn

and Sauer 1993).

The BBS has been instrumental in documenting declines in many breeding bird
species since its inception (Robbins et al. 1989, Terborgh 1989). While the causes and

extent of many declines have been controversial (James et al. 1996, James 1998), they
have generally been attributed to a variety of interrelated factors, including habitat

fragmentation and destruction (Robbins et al. 1989), landscape change (F lather and Sauer

1996), nest predation (see Heske et al. 2001 for review), parasitization (Robinson et al.

1995), and direct mortality due to events (e.g., culling by farmers) on the wintering-
grounds of the neotropics (Rappole and McDonald 1994, Basili and Temple 1999).

Notably absent from the potential mechanisms considered responsible for influencing
breeding bird abundances are the landowners that live in the proximity of the BBS routes.
Specifically, because private landowners are the ultimate controllers of their land, they
may be carrying out a wide variety of actions that could, if taken cumulatively (i.e.,
integrated) across large areas, either positively or negatively influence bird abundances
and distributions. Because of the potential for significant landowner effects there has
been increased attention directed towards the integration of social and economic

components into questions of avian distributions (Hostetler 1999).

49

In directing attention towards how landowners may be influencing avian species it
is first important to consider what specific activities they may be pursuing on their land.
Arguably, the most important factors to focus on are those that alter or affect the habitat
used by birds or directly impact bird species. These factors include food and nesting
supplementation, alteration or maintenance of vegetation, introduction of exotic
predators, chemical application, landscaping and gardening, each of which has a known
relationship to birds, or has been highly promoted as having a relationship. For instance,
in the case of bird feeding, it is a highly promoted activity (e.g., Stokes and Stokes 1987,
Sargent and Carter 1999) that potentially alters the natural food regime by locating large
caches of energy dense food in easy to forage locations throughout the year. Similarly, in
the case of bird houses, it is a highly promoted activity (Sargent and Carter 1999)
designed to encourage birds, especially cavity nesting birds, to breed. As with feeding
and providing bird houses, the planting and maintenance of vegetation as well as
gardening and landscaping are highly promoted activities, designed to alter or maintain
the habitat for use by birds (Sargent and Carter 1999). Exotic predators (e. g., house cats

(Felis catus), also play a key role in negatively impacting bird species (Churcher and

 

Lawton 1987, Coleman and Temple 1993, Chapter 1). Fertilizing is another common
activity that can both increase and decrease bird habitat through changes in plant
productivity, invertebrate populations and toxicity (see Vickery et al. 2001 for review). In
the case of pesticide and herbicide application, they have a long history of negative
impacts associated with bird species (e.g., Carson 1962). Specifically, pesticides and
herbicides can both directly and indirectly influence bird populations (Newton 1995) by

affecting birds’ growth, development, and survival (Bishop et al. 1998a,b, Brickle et al.

50

2000), as well as through reducing or altering the food supply (invertebrates; Blackburn
and Arthur 2001).

While the aforementioned factors may appear self-evident as influential to bird
species, they have not been quantified in detail across landscapes, along BBS routes, or in
conjunction with one another. For instance, the US. Department of the Interior has
conducted a number of surveys (e.g., US. Department of the Interior et al. 1997)
addressing such issues of wildlife recreation as bird feeding. However, these surveys are
aggregated at geopolitical units and measured by number of people participating in a
given activity, thus providing no details on potential differences across landscapes or
among landowners. Similarly, the Cornell Laboratory of Ornithology conducts Project
Feeder Watch (e.g., Wells et al. 1998) each week during the winter months in North
America seeking to estimate the abundance of birds. A disadvantage of the feeder watch
program is that it again provides very little spatial or landowner data. Furthermore such
surveys as Project Feeder Watch have been directed towards amateur omithologists and
birders, and therefore may not be representative of the typical landowner.

Besides the lack of detailed information, avian research in human dominated
systems has been focused on, and continues to be directed toward, the effects that these
systems have on bird species (Marzluff et al. 1998) and not on what the landowners are
actually doing to influence birds. Given the fact that a wide number of businesses exist
that sell bird related products (e.g., bird food, bird houses), coupled with the great volume
of information from public and private organizations directed at landowners to encourage
bird use and visitation (e. g., Terres 1953, DeGraaf and Witrnan 1979, Stokes and Stokes

1987, Sargent and Carter 1999, Tufts and Loewer 1995 ), it is highly likely that many

51

more landowners are involved in activities that could influence bird abundances than
previously believed. However, even in the face of this likelihood, no data exist that seek
to address what activities landowners are either intentionally or unintentionally engaged
in on their land or how they may be correlated, especially across large spatial scales.

Besides simply investigating what activities landowners may be carrying out on
their land, it is also essential to investigate if there are socio-demographic factors that
differentiate those landowners involved in a given activity from those that are not. The
reason for this importance is that if differences exist they may be valuable in targeting
management and conservation efforts on both private lands and public locations that have
a large private land component nearby. Thus, it is relevant to consider how factors such
as age, sex, household size, education, occupation, and income are related to the specific
activities. For instance, men and women often exhibit differences of opinion with regard
to species conservation (Kellert and Berry 1987, Czech et al. 2001). Integrating the
socio-demographic component into the analyses not only provides a clearer picture of
what may be related to specific actions, but can also provide more precise information on
whom to focus with regard to conservation planning, modeling avian populations, and
management.

As part of a larger effort to understand the social and ecological factors
influencing breeding bird abundances along BBS routes (Lepczyk et al. 2002, Chapters 1
and 3), we sought to investigate specific activities that private landowners were likely
carrying out on their land. These activities included feeding birds, providing bird houses,
planting and maintaining vegetation for benefit of birds, gardening, landscaping,

fertilizing, and applying pesticides and herbicides. With regard to these activities we

52

were specifically interested in discerning (1) the proportion of landowners involved in
each activity, (2) if participation in the activities was correlated, (3) the number and
density of bird feeders and houses, (4) if differences existed in activity participation
across routes of different socio-demographic character, and (5) if the population of
landowners that carried out a given activity were socio-demographically different from
the population of landowners that did not carry out the activity. In addition we sought to
test a set of three a priori hypotheses relating the specific activities to socio-demographic
factors. Specifically, that the age of the landowners involved in ( 1) bird feeding, (2)
providing bird houses, and (3) planting and maintaining vegetation would be significantly
older than those landowners not participating in these activities. We predicted an older
age based upon the 1996 National Survey of Fishing, Hunting, and Wildlife-Associated
Recreation (US. Department of the Interior et al. 1997) which found an increasing

percent of respondents that partook in these activities as age increased.

METHODS

To address the research questions, test our hypotheses, and match the scale of
study areas with locations where long-term data on bird abundance and distribution have
been collected (Vogt et al. 2002), we used three breeding bird survey (BBS) routes (route
numbers 53, 167, and 168) in Southeastern Michigan, United States (Figure 2.1), where
>90% of the land is privately owned. We chose these three routes because they represent
a continuum from rural to urban landscapes, based on their geographic locations, average

land parcel sizes, and socio-demographic compositions. Specifically, route 53 (hereafter

53

termed Rural) is very rural, has a low population density, large land parcels, and is
removed from any large city center or urban location. Route 168 (hereafter termed
Urban) ranges from being very suburban to being urban, has a high population density,
small land parcels, and transects or parallels residential locations and city centers.
Finally, route 167 (hereafter termed Suburban) straddles the demographic differences
between routes 53 and 168 by being suburban, with intermediate population density and
land parcel sizes, and runs parallel to (but never intersects) large residential and city
center locations. In addition, all three routes occur in a heterogeneous and human
dominated region that is undergoing rapid urbanization (Rutledge and Lepczyk 2002), _
which is representative of many other regions in North America. The last reason for
selecting these three routes is that they remain active BBS routes, monitored annually by
the United States Fish and Wildlife Service, which allows for firture evaluations to be
conducted, and hence, comparisons made over time.

To integrate information about human behaviors into the understanding of
landowner impacts on bird abundance, we conducted a social survey of landowners. For
our study, we chose all private landowners who owned property immediately adjacent to
the road along which each of the three BBS routes is run. We identified the landowners
through a combination of driving each route and using county tax records and plat maps.
Utilizing this combined approach we identified a total of 1,694 private landowners (331
on Rural, 390 on Suburban, and 973 on Urban).

We administered the survey instrument between October and December of 2000
following the Total Design Method (Dillman 1978, 2000). The survey instrument and

procedures were fully evaluated for ethical appropriateness by the Michigan State

54

University Committee on Research Involving Human Subjects prior to mailing. To
encourage landowners to respond to the survey we also established a toll-free telephone
line and offered an incentive prize drawing. Briefly, an initial survey (Appendix A and
B) was mailed during the first week of October 2000. A postcard reminder/thank you
was sent out two weeks later (Appendix C). Finally, a second survey was sent out two
weeks after the postcard (Appendix D).

Our sampling framework was designed to capture only private landowners, hence,
any survey returned from a church, business or public land owner that might have
accidentally been included in the initial sample was removed from the study. Similarly,
surveys that were returned as undeliverable by the United States Postal Service (USPS),
where the recipient was deceased, or where different landowners had the same address as
another landowner and were returned as undeliverable by the USPS, were removed from
the sample. Surveys received after December 31, 2000 were not included in any analyses.
If landowners owned multiple parcels that were not connected to one another, then they
were asked to complete the survey in relation to only one of the parcels. However, if the
landowner owned multiple parcels that were all contiguous with one another, then they
were asked to fill out the survey in relation to the entire block of land. Surveys that were
returned blank (i.e., not filled out) or contained notes indicating no interest in
participating in the survey were considered a non-response. Similarly, landowners that
called to indicate they were unable or had no desire to participate in the survey were
considered non-respondents. Non-respondents were included in the final corrected
sample size.

To ascertain the activities that landowners were involved with on their land that

55

could influence bird species along BBS routes we asked the following questions in our
survey: (1) Does anyone in your household feed birds on your property (yes, no)? (2) In
which months of the year do you or members of your household feed birds (January
through December)? (3) How many bird feeders do you have on your property? (4)
Approximately how many years have you or members of your household been feeding
birds? (5) Do you plan to continue feeding birds on your property in the future (yes, no,
unsure)? (6) Are there any bird houses on your property (yes, no)? (7) How many bird
houses do you have? (8) Approximately how many years have you had bird houses on
your property? (9) Do you plan to continue having bird houses on your property in the
future (yes, no, unsure)? (10) Have you planted vegetation or maintained landscaping on
your property in order to benefit or encourage use by birds (yes, no)? (11) (Referring to
the previous question) What types of vegetation have been planted (check all that apply:
fruit trees or bushes, ornamental shrubs or bushes, vines, other (please specify))? (12)
Which of the following activities do you carry out on your land (check all that apply:
gardening, landscaping, fertilizing, spraying pesticides or herbicides, other (please
specify))?

Following the questions related to specific landowner activities we sought to
acquire basic socio-demographic information about respondents by asking the following
questions: (13) Approximately how large is your parcel of land (ACRES)? (14) About
how long have you owned or lived on this parcel of land (YEARS)? (15) In what year
were you born l9____? (1 6) Are you: Male, Female? (17) How many people currently
live in your household? (18) What is your primary occupation? (19) Do you have a house

or residential structure on your land (yes, no)? (20) What is the approximate size of the

56

 

house or residence (less than 1,000 square feet, 1,000 to 1,499 square feet, 1,500 to 1,999
square feet, 2,000 to 2,499 square feet, 2,500 to 2,999 square feet, 3,000 to 3,499 square
feet, 3,500 square feet or larger, unsure)? (21) What is the highest level of school
completed or degree you have received (Some school completed, but no high school
diploma; High school graduate or GED (general equivalency diploma); Some college, but
no degree; Associates degree in college; Bachelor’s degree; and, Master’s, professional,
or doctoral degree)?

In cases where the respondents did not explicitly follow the survey instructions,
we edited the data as follows. For fill-in—the-blank questions that asked for a single
numeric response, but for which the respondent put a range, we took the arithmetic mean
as the value. Questions that were contingent upon a previous question being answered,
but which had not been answered, were converted to blank (i.e., no data) entries. In the
cases where respondents were asked for only a single response to a categorical question,
but filled in two blanks, we used a coin toss to decide the answer. For the open-ended
question of primary occupation we categorized the responses into seven classes. The first
six classes correspond to the six broad categories defined in the 1990 US. Census (US.
Department of Commerce 1993). Specifically, these occupations are (1) managerial and
professional specialty, (2) technical, sales, and administrative support, (3) service, (4)
farming, forestry, and fishing, (5) precision production, craft, and repair, and (6)
operators, fabricators, and laborers. The remaining class consisted of respondents who
were not employed, which included homemakers, stay-at-home parents, widows,
students, disabled persons, those on public assistance, and retired individuals with no

indication of previous occupation. If the respondent chose not to indicate their

57

occupation (n = 47), were under the age of eighteen (n = l), or where no logical category
could be determined (n = 16; e. g., one respondent listed their occupation as “leader,”
which provided no details to appropriately classify him/her) the occupation category was
left blank.

Statistical analyses were performed using SYSTAT 10 (SPSS 2000). Initial
comparisons across BBS routes were carried out with ANOVA, with route differences
compared using Tukey’s HSD procedure (Zar 1996). For route comparisons based on the
proportion of landowners engaged in an activity a two-way contingency table with a
Pearson Chi-square test was used. Similarly, comparisons of respondents based on
gender and occupation across routes were analyzed with one- and two-way contingency
tables with a Chi-square test statistic. Correlations between each possible pair of
activities were compared with a two-way contingency table using a Chi-square test
statistic. Initial comparisons between the population of landowners involved in a given
activity and the population that was not, in relation to age, number of people in the
household, education, and house size, were analyzed using a t-test. If a significant
difference between the two populations was found then a general linear model that
incorporated the factor of route was tested. Similarly, if route was found to be a
significant term, then the model with the interaction between route and the socio-
demographic factor was tested. For comparisons between the two populations based on
gender and occupation a two-way contingency table was utilized. With regard to the
question about approximate size of the residence we excluded the “unsure” category from
all analyses. Data are reported as means i SE (as 100% of the population was sampled,

but only ~59% responded), unless otherwise noted, with a p-value of s 0.05 considered

58

significant.

Of the 1,694 landowners initially identified, 40 were removed from consideration
because they were a business or church, had property outside the sampling region, already
responded based on another parcel of land within the study landscapes, or their address
information was incorrect, thus reducing the corrected population size to 1,654. Among
these 1,654 we received 968 completed surveys, yielding a 58.5% response rate.
Response rates in different landscapes were 64.8% for Rural (212 of 327), 61.5% for
Suburban (233 of 379), and 55.2% for Urban (523 of 948), which were significantly

different (x2 = 11.11; df= 2; p = 0.0039).

RESULTS

Landowner .S'ocio-demographic Composition

Respondents varied in age from 13 to 93, with the average being 50.6 years old
(Table 2.1). There was a significant difference in ages across the three landscapes (F =
6.64; df = 2, 927; p = 0.0013), in which the Suburban and Urban landscapes differed (p =
0.0021) and the Rural and Urban landscapes marginally differed (p = 0.054). Household
size ranged from 0 to 8 persons, with an average of 2.85 people per household (Table
2.1). No differences existed across the landscapes based upon household size (F = 0.33;
df = 2, 932; p = 0.721). Of the 934 respondents who reported their gender, 498 (53.3%)
were male and 436 (46.7%) were female (Table 2.1). Over all landscapes there was a
significant difference (x2 = 4.12; df = 1; p = 0.042) in the proportion of respondents based

on gender, but this disappeared when route was included (x2 = 1.66; df = 2; p = 0.44;

59

Table 2.1). The average respondent had some college education, but no degree (Table
2.1) with the amount of education ranging from those with no formal diploma at the high
school level to those with graduate and professional degrees. Overall, the educational
level was significantly different by landscape (F = 30.39; df = 2, 929; p < 0.0000005) and
among each pair of landscapes (p < 0.001). A total of 907 (95.2%) respondents indicated
that they had a house or residential structure on their land. The average respondent’s
house size was between 1,500 and 2,000 ft2 (139.4 and 185.9 m2; Table 2.1), but varied
significantly by route (F = 25.27; df = 2, 864; p < 0.0000005). Specifically, the Suburban
landscape differed from both the Urban landscape (p = 0.000002) and the Rural landscape
(p = 0.000003). The average respondent had a land parcel of 7.8 ha (Table 2.1), but varied
significantly by landscape (F = 14.41; df = 2, 936; p = 0.000001), with the Rural
landscape differing from the Suburban (p = 0.0033) and the Urban (p = 0.000002)
landscapes. The types of occupations were significantly different (x2 = 70.17; df = 12; p
< 0.0000005) across the three landscapes as evidenced by the drastic differences in

proportions per occupation (Table 2.2).

Landowner Activities

A total of 635 (65.6%) landowners fed birds on their land, with 620 using at least
one bird feeder, and the remaining 15 presumably putting food only on the ground. Of
these 635 landowners, the percent that fed birds in each landscape was quite similar (x2 =
0.455; df= 2, p = 0.80): 64.6% (137 of212) for Rural, 67.4% (157 of 233) for Suburban,
and 65.2% (341 of 523) for Urban. The number of bird feeders ranged from 1 to 17.5,

with an average of 2.98 i 0.08 (Figure 2.2). On the basis of the land owned by

60

respondents, the average respondent had 5.78 i 0.51 bird feeders/ha. Both the number (F
= 3.31; df= 2, 617;p = 0.037; Figure 2.3A) and density (F = 16.89; df= 2, 599; p <
0.0000005; Figure 2.3B) of bird feeders varied significantly across all landscapes. With
regard to specific landscape differences, there was a marginal difference in the number of
bird feeders between the Rural and Urban landscapes (p = 0.06), and significant
differences in bird feeder density between Suburban and Urban landscapes (p =
0.000004) and the Rural and Urban landscapes (p = 0.000026). The average landowner
fed birds 9.30 i 0.13 (N = 627) months out of the year and had been feeding birds on
their property for 11.04 :1: 0.44 (N = 626) years (Table 2.3). Bird feeding occurred with
the greatest frequency during the winter months and the least during the summer months
and showed a similar pattern across all three landscapes (Figure 2.4). A significant
difference existed across landscape (F = 4.09; df = 2, 624; p = 0.017) based on the
number of months per year that landowners fed birds (Table 2.3); this was due to a
significant difference between the Urban and Suburban landscapes (p = 0.012). No
difference existed across landscapes (F = 1.38; df = 2, 623; p = 0.25) based on number of
years that landowners had been feeding birds (Table 2.3). Nearly all landowners (96.4%)
that fed birds expressly indicated that they will continue feeding birds into the future.

A total of 442 (45.7%) landowners had at least one bird house on their property,
with the percent of landowners along each route showing a similar proportion of
involvement (45.8% for Rural, 50.6% for Suburban, and 44.2% for Urban; X2 = 2.732; df
= 2; p = 0.26). The number of bird houses ranged from 1 to 48, with an average of 3.76 i
0.19 (Figure 2.5). On the basis of the land owned by respondents, the average landowner

had 5.17 :t 0.62 bird houses/ha. Both the number (F = 8.02; df= 2, 439; p = 0.00038;

61

Figure 2.6A) and density (F = 5.33; df= 2, 429; p = 0.0052; Figure 2.6B) of bird houses
were significantly different across the three landscapes. Specific route differences existed
between both the Rural and Urban landscapes (p =0.00019) and the Rural and Suburban
landscapes (p = 0.036) for the number of bird houses (Figure 2.6A), while on a per unit
area basis only the Urban and Suburban landscapes (p = 0.0038) were different. The
average landowner had a bird house on their land for 9.35 i 0.54 (N = 438) years (Table
2.3). No difference existed across landscapes (F = 0.94; df = 2, 435; p = 0.39) based on
number of years that landowners had bird houses on their land (Table 2.3). As with bird
feeding, nearly all landowners (96.4%) that had bird houses on their property planned to
continue having them.

A total of 529 (54.6%) respondents planted vegetation or maintained landscaping
on their property in order to benefit or encourage bird use. The proportion of landowners
that planted or maintained vegetation on their property was significantly different across
the three landscapes ( X2 = 6.113; df = 2; p = 0.047), which was due to the lower
proportion in the Urban landscape (51.1% for Urban, 57.9% for Suburban, 59.9% for
Rural). Of the 529 respondents, 524 indicated that they planted at least one type of the
following vegetation: fruit trees or bushes, ornamental shrubs or bushes, vines, or “other.”
Of the respondents indicating which types of vegetation they planted 69.1% planted fruit
trees or bushes, 74.2% planted ornamental shrubs or bushes, 41.4% planted vines, and
39.9% planted “other” types of vegetation (Table 2.4). Proportionally, across landscapes
there was no difference in the frequency of planting fruit trees and bushes (x2 = 0.65; df =
2; p = 0.72) or “other” types of vegetation (x2 = 1.99; df = 2; p = 0.37), but there was a

difference in frequency of planting both ornamental shrubs and bushes (x2 = 7.27; df = 2;

62

p = 0.026) and vines (Table 2.4; X2 = 6.26; df = 2; p = 0.044). Specifically, the Suburban
landscape had a far greater proportion of respondents that planted ornamental shrubs and
bushes than the Rural or Urban landscapes (Table 2.4). In contrast, landowners along the
Suburban landscape planted a lower proportion of vines than Rural or Urban respondents
(Table 2.4).

Out of 912 respondents that answered the question about gardening, landscaping,
fertilizing, and spraying pesticides or herbicides 861 (94.4%) carried out at least one of
the activities (Table 2.5). No difference existed across the landscapes in the frequency of
respondents that gardened (X2 = 1.92; df = 2; p = 0.38), landscaped (x2 = 1.90; df = 2; p =
0.39), or fertilized (X2 = 0.06; df= 2; p = 0.97; Table 2.5). However, there was a
significant difference in the frequency of respondents that applied pesticides or herbicides
across landscapes (x2 = 22.17; df = 2; p = 0.000015), with the greatest frequency on the

Rural landscape and the least on the Urban landscape (Table 2.5).

(.‘orrespondence Between Activities
The seven activities investigated allowed for 21 ((N - 1)!) pairwise comparisons,

of which 16 were significantly related with one another (Table 2.6).

Comparison oflandowners Participating in Activities Versus Non-Participants

The average age (N = 615) of the respondents that fed birds was 51.7 i 0.54 years
compared to 48.5 :t 0.77 years for respondents not feeding birds (N = 305), yielding a

significant difference in age (t = 3.401; df = 918; p = 0.0007) and support for the

63

prediction that landowners that feed birds would be older than those who do not.
Whether or not a landowner fed birds, based on their age, remained significantly different
(F =11.28; df = 1, 916; p = 0.00082) with the incorporation of the insignificant
categorical variable of landscape (F = 0.16; df = 2, 916; p = 0.85). The household size of
landowners that fed birds was 2.85 :1: 0.06 compared to 2.86 3: 0.08 that did not feed birds,
indicating no significant difference (t = -0.077; df = 923; p = 0.94). In terms of
education, landowners that fed birds had a lower level of formal education (3.42 i 0.06;
see Methods for description) compared to landowners that did not feed birds (3.71 :1:
0.08), resulting in a significant difference (t = -2.81; df = 920; p = 0.005). Educational
level between respondents that fed birds and those that did not remained significantly
different (F = 9.19; df = l, 918; p = 0.0025) with the inclusion of landscape, which was a
significant variable (F = 0.81; df = 2, 918; p = 0.44). A gender difference existed when
comparing respondents that fed birds versus those not feeding birds (x2 = 4.37; df = 1; p
= 0.037); a greater percentage of women indicated that they feed birds than men (58.1%
women vs. 41.9% men). The significant difference remained for gender (F = 4.25; df = 1,
920; p = 0.04) when landscape was included, which was not a significant variable (F =
0.21; df = 2, 920; p = 0.81). Landowners that fed birds did not differ with regard to
occupation compared to landowners that did not feed birds (x2 = 8.70; df = 6; p = 0.19).
Finally, no difference existed between the two groups based upon the size of the house or
residence (t = -0.065; df= 855; p = 0.95).

The average age (n = 430) of the respondents that had bird houses on their
property was 52.3 :t 0.64 years compared to 48.8 i 0.60 years for respondents not having

bird houses (n = 487), yielding a significant difference in age (t = 3.999; df = 915; p =

64

0.000069). This difference provides support for the second prediction that landowners
providing bird houses would be significantly older than those who did not. The
significant difference in ages remained (F = 14.62; df = 1, 913; p = 0.00014) with the
incorporation of landscape, which was not significant (F = 0.86; df = 2, 913; p = 0.42).
Landowners that had bird houses had an average of 2.79 :l: 0.07 living in their residence
versus 2.92 i 0.06 people those without, yielding no difference (t = -1.490; df = 920; p =
0.14). Similarly, no difference existed (t = -0.372; df = 917; p = 0.71) between
respondents that had bird houses (3.51 i 0.07) and those that did not (3.55 :t 0.07) based
upon educational level. The approximate size of the residences (1,500 to 2,000 sq. ft.)
were similar between landowners that had bird houses and those that did not (t = 0.514;
df = 853; p = 0.61). No gender difference existed between landowners that provided bird
houses and those that did not (x2 = 1.99; df = l; p = 0.16). Similarly, no difference
existed based upon occupation between landowners that provided bird houses and those
that did not (X2 = 3.82; df= 6; p = 0.70).

Landowners that planted or maintained vegetation on their property were on
average significantly older (51.7 :t 0.59 versus 48.9 at 0.66; t = 3.159; df= 916;p =
0.0016) than landowners that did not. This age difference supports the third prediction
that landowners involved in planting and maintaining vegetation would be older than
those who do not. The significant difference remained (F = 8.16; df = l, 914; p = 0.0044)
with the significant incorporation of landscape (F = 3.35; df = 2, 914; p = 0.036). No
significant interaction occurred between landscape and whether or not a landowner
planted or maintained vegetation (F = 1.37; df = 2, 912; p = 0.26). The average number

of people living in households that planted or maintained vegetation was 2.81 :t 0.06

65

compared to 2.90 i 0.07 in households that did not plant or maintain vegetation,
indicating no difference (t = -l .007 df = 921; p = 0.31). Similarly, no difference existed
(t = 0.052; df = 918; p = 0.96) between respondents that planted vegetation (3.53 :t 0.06)
and those that did not (3.52 3: 0.07) based upon educational level. The approximate size
of the residences (1,500 to 2,000 sq. ft.) were similar between landowners that planted
and maintained vegetation and those that did not (t = -0.196; df = 854; p = 0.84). A
gender difference existed between landowners that planted and maintained vegetation and
those that did not, with female respondents indicating they participated more frequently
then male respondents (x2 = 8.00; df = 1; p = 0.0047). This gender difference remained
(F = 7.79; df = 1, 918; p = 0.005) with the significant incorporation of landscape (F =
3.71; df = 2, 918; p = 0.025), but did not have a significant interaction with gender (F =
0.44; df = 2, 916; p = 0.64). No difference existed in the proportion of landowners
planting and maintaining vegetation based upon their occupation (x2 = 4.37; df = 6; p =
0.63).

Landowners that gardened were slightly older (50.9 :t 0.5 vs 49.1 i 0.9) than
landowners that did not, but not significantly so (t = 1.802; df = 881; p = 0.072).
Landowners that gardened had a similar number of people in their household as non-
gardeners (2.9 :1: 0.05 versus 2.8 :t 0.09), indicating no difference (t = 1.358; df = 883; p =
0.17). The level of formal education between landowners that gardened (3.5 :t 0.06) and
those that did not (3.6 i 0.10) were similar (t = -0.826; df= 881 ; p = 0.41). Landowners
that gardened had similar sized residences as those that did not (t = -0.064; df = 824; p =
0.95). A gender difference existed between landowners that gardened and those that did

not, with female respondents participating in greater frequency than male respondents (x2

66

= 10.16; df= l;p = 0.0014). This difference remained significant (F = 10.39; df= 1,
880; p = 0.0013) when the insignificant variable of landscape (F = 0.75; df= 2, 880; p =
0.47) was incorporated into the model. No difference existed in the proportion that
gardened based upon their occupation (x2 = 8.53; df = 6; p = 0.20).

Landowners that landscaped their property were significantly younger (49.1 d:
0.52) than landowners that did not (54.1 :t 0.85; t = -4.961; df= 881 ; p = 0.000001). The
addition of landscape to the model was not significant (F = 1.41; df = 2, 879; p = 0.25),
while age remained significant (F = 24.75; df = l, 879; p = 0.000001). Similarly,
landowners that landscaped had significantly (t = 2.486; df = 883; p = 0.013) more people
living in their residences (2.9 i 0.05 versus 2.7 i 0.09). The addition of landscape to the
model was not significant (F = 1.35 df = 2, 881; p = 0.26). Landowners that landscaped
had marginally more education than landowners that did not (3.60 i 0.06 versus 3.38 d:
0.09; t = 1.915; df = 881; p = 0.056). In terms of house size, landowners that landscaped
had significantly larger homes (1,500 to 2,000 it2 compared to 1,000 to 1,500 ftz) than
landowners that did not (t = 4.505; df = 824; p = 0.000008). The difference remained
based on house size (F = 18.94; df = l, 822; p = 0.000015) when the insignificant term of
landscape was included (F = 0.08; df = 2, 822; p = 0.92). There was no difference in the
proportion of men or women that landscaped and those that did not (x2 = 2.70; df = 1; p =
0.10). However, a difference existed in the proportion of landowners that landscaped
based upon their occupation (x2 = 25.28; df = 6; p = 0.0003), with managerial and
professional respondents participating in the greatest frequency and the farming, forestry,
and fishery respondents participating in the lowest frequency. The difference remained (F

= 4.15; df = 6, 846; p = 0.00041) with the addition of landscape, which was not

67

significant (F = 0.16; df= 2, 846; p = 0.85).

Landowners that applied fertilizer on their property were the same age (50.4 i
0.63) as those that did not (50.4 i 0.64), indicating no difference (t = -0.210; df = 881; p
= 0.83). Similarly, there was no difference in the number of people living in the
residences of those that fertilized (2.9 d: 0.07) compared to those that did not (2.8 :t 0.07; t
= 1.584; df= 883; p = 0.11). No difference existed (t = -0.243; df= 881;p = 0.81), in
terms of education, between landowners that fertilized and those that did not. Likewise
no difference existed between landowners that fertilized compared to those that did not
based upon the size of the residence (t = 1.260; df = 824; p = 0.21). No difference existed
in the proportion of each gender that fertilized or not (X2 = 0.79; df = 1; p = 0.38).
However, a difference existed in the proportion of landowners that fertilized based upon
their occupation (x2 = 12.72; df = 6; p = 0.048), with the managerial and professional
respondents participating in the greatest frequency and the service respondents
participating in the lowest frequency. This significant difference based on occupation
remained (F = 2.22; df = 6, 846; p = 0.040), with the addition of landscape, which was
not significant (F = 0.29; df= 2, 846;p = 0.75).

Landowners that applied pesticides and/or herbicides to their property were of a
similar age (51.4 i 0.9) as those that did not (50.1 i 0.5; t = 1.256; df= 881;p = 0.21).
Similarly, no difference existed in the size of the household between those that applied
pesticides and those that did not (t = 0.985; df = 883; p = 0.32). Likewise no difference
existed in the educational level of landowners that applied pesticides compared to those
that did not (t = 1-067; df = 881; p = 0.29). However, landowners that applied pesticides

and/or herbicides did have significantly larger homes than landowners that did not apply

68

them (t = 2.716; df = 824; p = 0.0067). The significant difference in house size remained
(F = 5.99; df= 1, 822; p = 0.015) with the significant incorporation of landscape (F =
8.09; df = 2, 822; p = 0.00033). There was no significant interaction between landscape
and whether or not a landowner applied pesticides and/or herbicides based upon house
size (F = 1.91; df = 2, 820; p = 0.15) when the interaction term was added to the model.
No difference existed in the proportion of each gender that applied pesticides and/or
herbicides compared to those that did not (x2 = 0.06; df = 1; p = 0.80). A difference did
exist in the proportion of landowners that applied pesticides and/or herbicides based on
their occupation (X2 = 34.20; df = 6; p = 0.000006), with the managerial and professional
respondents participating in the greatest frequency and the service respondents
participating in the lowest frequency. The difference remained significant (F = 4.48; df =
6, 846; p = 0.00018) with the incorporation of landscape, which was significant (F = 7.02;
df= 2, 846; p = 0.00095). However, there was no interaction (F = 0.73; df = 12, 834; p =

0.72) between landscape and occupation when it was included in the model.

DISCUSSION

Of greatest note, our results highlight the fact that cumulatively across the
landscape a significant portion (~50% or more) of landowners are both intentionally and
unintentionally engaged in activities that can influence avian populations, except for
pesticide and/or herbicide application. Even taking a conservative approach, which
assumes that only the landowners involved in at least one of the activities investigated

responded to the survey (i.e., all non-respondents were not engaged in any activity), the

69

percent of landowners across the landscape engaged in an activity remains large (Table
2.7). On the other hand, taking a liberal approach, which assumes that every non-
respondent was engaged in each activity, the percent of landowners involved in any of the
activities becomes extremely large (Table 2.7). Although it is implausible that all non-
respondents are engaged in each of the activities, it is also unlikely that all non-
respondents were nonparticipants in these activities. As a result the actual percent of
landowners engaged in each activity as reported here should fall within the range of
conservative and liberal estimates.

Because the landscapes of Southern Michigan are 90% privately owned (Rutledge
2001), the proportion of landowners engaged in each activity covers a large portion of the
total landscape. Consequently, at both the individual land parcel and the landscape
scales, landowners are in all likelihood having a large and sustained influence on avian,
and other wildlife species, abundances and populations. Furthermore, as the spatial
patterns of human habitation in this portion of Michigan are not random, but tend towards
aggregation near natural amenities, such as bodies of water (Walsh 2000), which are also

used by bird species, the effects could be more pronounced.

Specific Activities

Although past studies related to bird feeding have investigated the frequency of
feeder use by a species (Brittingham and Temple 1989), how long it takes birds to find a
feeder (Wilson 2001), the role they play in disease transmission (Brittingham and Temple
1986), the degree to which they facilitate predation (Dunn and Tessaglia 1994, Giesbrecht

and Ankney 1998), and the economics of bird feeding (Wiedner and Kerlinger 1990),

70

there has existed only a vague knowledge of what percent of the landscape might contain
feeders (US. Department of the Interior et al. 1997). Moreover, most previous attempts
at discerning aspects of bird feeding through survey methodologies have focused only on
birders and omithologists, not the average landowner. Thus, our finding that two out of
three landowners were engaged in feeding birds on their land not only provides concrete
data on the proportion of the landscape that has bird feeders, but the density with which
they occur. In terms of temporal feeding patterns, our finding that landowners feed an
average of nine out of twelve months a year is greater than the national average reported
by the USFWS (US. Department of the Interior et al. 1997). However the observation
that most bird feeding done in the winter months mirrors that of other studies (Cowie and
Hinsley 1988). As our findings suggest, the proportion of landowners that are involved
or potentially involved (Table 2.7) in bird feeding, coupled with the density of feeders
and length of time the feeders have been present, is great enough that at the landscape
scale there is likely a positive effect on species that either are obligate seed foragers (i.e.,
granivores), such as Northern Cardinals (Richmondena cardinalis), or can utilize seed in
their diet (e. g., some omnivores), such as Blue Jays (Cyanocitta gris_tat_a), or that can
forage on other foods provided by landowners (e.g., suet, nectar, and oranges), such as
woodpeckers and tanagers. Such positive effects have been noted by increased survival

of Carolina Chickadees (Poecile carolinensis) and Black-capped Chickadees (Poecile

 

 

atricapillus) during the winter in the Midwest (Brittingham and Temple 1988, Doherty
and Grubb 2002). Ultimately, the findings highlight the point that bird feeding is a long-
term and continuous activity that results in the landscape being covered with easily

accessible, energy dense sources of food for birds, that may well translate into higher

71

survival rates and population numbers for species that can utilize them.

Providing bird houses is akin to providing bird feeders in that it helps to promote
species visitation and habitation on one’s property. Thus, just as with bird feeding, there
exist many gray literature sources that promote the use of bird houses. In fact bird houses
are known to be used by nearly 50 bird species in North America (Payne and Bryant
1994). Thus, our finding that nearly half of the landowners reported having bird houses
on their land, even taken conservatively (Table 2.7), indicates that a large portion of the
landscape has supplemental housing opportunities for birds. While our survey did not
evaluate whether or not each bird house was being used each year, the high per parcel
densities (Figure 2.4B) coupled with their long-term presence indicates that bird houses
are likely at least aiding in the presence and survival of some species. Moreover, if
potential nesting habitat (e.g., snags, dead trees, low shrubs) has been lost on the
landscape, the establishment of bird houses may provide a compensatory mechanism by
which species are able to either continue persisting on the landscape or experience slower
declines than would be so if no bird houses were present.

Although an abundant amount of gray literature exists that encourages and/or
explains the importance of planting and maintaining vegetation to attract birds (Sargent
and Carter 1999, Tufts and Loewer 1995), relatively few estimates exist of the number of
landowners that actually carry out these activities. The closest estimate to be found is
from the 1996 National Survey of Fishing, Hunting, and Wildlife-Associated Recreation,
which found that approximately 15% of the individuals it surveyed planted or maintained
vegetation for the benefit of wildlife (U .S. Department of the Interior et al. 1997).

Taking the minimum estimate of landowners in our survey that planted or maintained

72

vegetation to be 32% (Table 2.7), our findings are double the previous estimate. Notably,
however, comparing individuals and “wildlife” from the USFWS survey with landowners
and birds from our survey is tenuous as they are not exact synonyms. Furthermore,
landowners in Southeast Michigan may be quite different than the average national
respondent. Given the large portion of landowners engaged in planting or maintaining
vegetation, it is also essential to note what types of plants landowners may be
encouraging on their property. In particular if landowners are actively planting or
maintaining vegetation that is exotic (which includes many omamentals), they could alter
the breeding success of certain bird species (Schmidt and Whelan 1999). Aside from
influencing the breeding success, birds can directly facilitate the dispersal of exotic
species by consuming fruits or seeds and defecating or regurgitating them elsewhere
(Hutchinson and Vankat 1998), thus facilitating the spread of exotic species across the
landscape as is occurring with Autumn-olive (Elaeagnus umbellata; K. Winnett-Murray,
personal communication). Thus, while our survey only broke categories down into vines,
fruit bearing plants, omamentals, and “other,” and not exotic versus native, it is likely that
a large portion of the landowners that planted vegetation did plant exotic species.

While gardening and landscaping may be viewed as similar to planting and
maintaining vegetation, they are inherently different activities. Furthermore, we
specifically framed the question about planting and maintaining vegetation with reference
to birds, whereas the questions regarding gardening and landscaping were not specifically
addressed with reference to birds. A difference was evident by the fact that less than 50%
of landowners either gardened or landscaped in conjunction with planting and

maintaining vegetation for the benefit of birds (Table 2.6). While gardening and

73

landscaping can be used to promote bird habitat (Terres 1953, Sargent and Carter 1999),
that does not mean that they may not also cause reductions in habitat for some species,
either through competition or simply because only certain species can utilize the habitat.
Ultimately, whether gardening is beneficial or detrimental to birds overall is unknown,
but our data indicate that regardless of its influence that it is a highly prevalent activity.

Fertilizer use can have both positive and negative impacts on bird species.
Specifically, fertilizing can change the vegetation structure markedly, which affects
nesting locations for grassland birds (see Vickery et a1. 2001 for review), whereby some
species gain preferred habitat and other species lose it. Similarly, some types of fertilizer,
such as manure, can increase bird abundances by increasing the soil-dwelling
invertebrates, whereas inorganic fertilizer can cause decreases in both seed availability
and soil invertebrates (Vickery et al. 2001). Although half of the landowners (Table 2.5)
applied fertilizer to their property, we did not ascertain the type of fertilizer used, the
frequency of input, or where it was applied on the property. Regardless, the fact remains
that at the landscape scale (Table 2.7) landowners are inputting a large amount of
fertilizer that may directly or indirectly influence bird species.

Since Rachel Carson’s seminal work Silent Spring (Carson 1962), there has been
a steady track of research identifying the effects of pesticides and herbicides on bird
species. Although many of the most notable chemicals (e. g., Chlordane, DDT, etc.) have
been phased out of use, there remain a number of current chemicals that are displaying
direct effects on the growth and development of birds (Bishop et al. 2000). Moreover,
even if pesticides and herbicides display no effects on the birds themselves they often

have the indirect effect of reducing food availability (Pinowski et al. 1994, Newton

74

1995). Thus, our finding that one in four landowners apply pesticides or herbicides to
their land represents somewhere between 14% to 55% (Table 2.7) of the landscape that
may be unsuitable or less suitable as bird habitat, assuming equal size parcels. Moreover.
the applications were most proliferate along the Rural landscape and among landowners
that are primarily farmers, and thus had larger land parcels. As a result, many potential
habitat locations may be less suitable than indicated through either land cover (Rutledge
2001) or parcel size.

In addition to the seven landowner activities measured here, we previously found
that 26.1% of the same landowners surveyed had house cats that were allowed outdoors
(Chapter 1). Considering the activity of allowing cats outdoors in conjunction with the
other seven activities, results in a total of 95% landowner participation in at least one of
the activities, with the average landowner engaged in four (Figure 2.7). Moreover, the
majority of these activities show strong correlation with one another (Table 2.6)

indicating that there are likely synergistic effects of these activities.

Differences in Activities Across Landscapes

Across the three landscapes we found many marked differences in both the
landowners and the activities they engaged in. Specifically, we found differences in the
age, education, house size. occupation, and parcel size across the three routes (Tables 2.1
and 2.2). Similarly, we found significant differences in the number and density of bird
feeders (Figures 3A and 3B), the months spent feeding (Figure 2.4), the number and
density of bird houses (Figures 2.6A and 2.6B), the proportion of landowners that planted

or maintained vegetation for birds (Table 2.4), the proportion that planted omamentals

75

and vines (Table 2.4), and the use of pesticides (Table 2.5). However, we found no
differences in either the gender of the respondent or the number of residents living on the
property (Table 2.1). Similarly, we found no difference in the proportion of landowners
that feed birds or have bird houses, the length of time that landowners supplied bird food
or houses, or in the proportions that planted fruit, gardened, landscaped, or fertilized
(Table 2.5).

The result of differences across the three landscapes indicates that there is a
marked difference across the rural to urban continuum. Specifically, landowners in the
Rural landscape had the highest number of bird feeders (Figure 2.3A) and houses (Figure
2.6A) as well as showed the greatest propensity to plant or maintain vegetation for birds
(Table 2.4) and use pesticides and herbicides (Table 2.5). On the other hand, the Rural
landowners had the lowest density of bird feeders (Figure 2.3B), which is likely due to
their larger parcel size, and had bird houses on their property the shortest amount of time.
As a result, Rural landowners are influencing their land in such a way as to encourage
bird habitation, but are using chemical inputs that may have a certain counteracting effect.

Landowners living in the Suburban landscape had been involved in providing bird
food and houses (Table 2.3) the longest (or similarly as long) as well as showed the
greatest propensity to plant ornamental vegetation (Table 2.4). However, the Suburban
landowners had the lowest densities of bird feeders (Figure 2.3 B) and houses (Figure
2.68), spent the least months feeding per year (Table 2.3), and planted the least amount of
vines (Table 2.4). The result of these activities indicates that suburban landowners have a
long-term interest in promoting bird habitat.

In the case of the Urban landowners, they had the greatest density of bird feeders

76

(Figure 2.3B) and houses (Figure 2.6B), spent the most months feeding birds (Table 2.3),
and had bird houses as long as the Suburban landowners. On the other hand, Urban
landowners had the lowest number of bird feeders (Figure 2.3A) and houses (Figure
2.6A), planted or maintained vegetation the least, and had the lowest pesticide and
herbicide application (Table 2.5). While the numbers of feeders and houses were lower,
they were at very high densities. Coupled with the high density of supplementation is
also the fact that Urban landowners used the lowest amount of pesticides and herbicides,
which together could result in more highly suitable habitat for birds than might be
previously thought. Taken together the differences in activities across the landscapes

lend credence for the differences in bird abundances and diversity often noted along urban

to rural gradients or in urban contexts (e.g., Emlen 1974, Hohtola 1978, Cam et al. 2000)

Hypotheses Tested

Based upon the 1996 National Survey of Fishing, Hunting, and Wildlife-
Associated Recreation (US. Department of the Interior et al. 1997) we had predicted that
landowners involved in (1) bird feeding, (2) providing bird houses, and (3) planting and
maintaining vegetation for birds would be older than nonparticipants. As our results
highlight, we found that for each of these three activities the landowners that participated
were significantly older than the nonparticipants, yielding support for our predictions.
Specifically, landowners that fed birds were 51.7 i 0.54 years old compared to 48.5 i
0.77 years for landowners that did not feed birds. Similarly, landowners that had bird
houses on their property were 52.3 :1: 0.64 years old compared to 48.8 i 0.60 years for

landowners that did not have bird houses on their property. Finally, landowners that

77

planted or maintained vegetation on their property were 51.7 i 0.59 years old versus 48.9

i 0.66 for landowners that did not plant or maintain vegetation on their property.

Comparison ofLandowners Participating in Activities versus Nonparticipants

Although a number of differences were found between landowners that carried out
a given activity and those that did not, there was no consistent trend or factor that
explained the differences across all activities (Table 2.8). For example, while a
significant difference in age was found for four of the activities, the landowners engaged
in them were not always significantly older. Besides the lack of consistent socio-
demographic factors that could explain the activities it is also important to note the fact
that most of the activities had only one or two socio-demographic variables that resulted
in a difference (Table 2.8). The lack of general trends among socio-demographic factors
across the different activities is not an unusual finding given the wide range of activities
investigated. However, as a consequence, the lack of general trends does indicate that
management and conservation programs cannot be targeted to a specific subset of

landowners based upon these factors.

Conclusion

The overall implications of our findings are that individual landowners are
engaged in a multitude of activities, that when taken collectively, are almost certainly
having some form of influence on avian species in particular and wildlife in general.
While the levels of these activities varied across the landscapes, they were carried out on

all landscapes and are not particularly unique to either Southeastern Michigan or the

78

Midwest. As a result our findings have direct relevance to the approximately 66% of the
United States land that is in private ownership (Dale et al. 2000) as well as in any location
where there is a large private land component. Moreover, because these activities likely
have synergistic effects that both positively and negatively influence birds species in
particular, and wildlife in general, our findings highlight the need to investigate the large

scale and interactive nature of these activities.

ACKNOWLEDGMENTS

We would like to thank the staff at the Ingham, Livingston, Oakland, and
Washtenaw county Equalization Offices, which allowed us access to landowner records.
Keith Pardieck and Jane Fallon at the USGS Patuxent Wildlife Research Center who
kindly assisted with providing maps and details of BBS routes. We are grateful to
Kimberly Baker, Jayson Egeler and Mike Mascarenhas for assisting with the survey
logistics and data entry. Robert Holsman and Sam Riffell provided critical review of the
draft survey. Daniel Brown, Katherine Gross, Nan Johnson, and Patricia Soranno
critically reviewed the manuscript and provided many helpful suggestions. Support for
this research was provided by a Michigan Agricultural Experiment Station grant and an
N.S.F. CAREER Award to J. Liu, a Michigan State University College of Social Science
Grant to J. Liu, A. Mertig, and P. Sorrano, and a US. EPA. Science To Achieve Results
(STAR) Fellowship (Grant no. U-91580101-0) to CA. Lepczyk. This paper was
submitted in partial fulfillment of the requirements for CA. Lepczyk’s doctoral degree in

Fisheries and Wildlife, and the Program in EEBB at Michigan State University.

79

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Vitousek, P.M., H.A. Mooney, J. Lubchenco, and J .M. Melillo. 1997. Human domination
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Vogt, K.A., M. Grove, H. Asbjomsen, K.B. Maxwell, D.J. Vogt, R. Siguréardottir, B.C.
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87

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Jersey.

88

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89

Table 2.2. Occupations of respondents by landscape. The percent of respondents (based

on proportion of column total) that worked in a given occupation within a route are

indicated in parentheses. For information on delineation of occupations please see

 

 

 

Methods.
Landscape

Rural Suburban Urban
Total Number of Respondents 201 220 483
Managerial and Professional Specialty 42 (20.9) 92 (41.8) 158 (32.7)
Technical, Sales, Administration Support 30 (14.9) 23 (10.5) 77 (15.9)
Service 12 (6.0) 6 (2.7) 22 (4.6)
Farming, Forestry, Fishing 25 (12.4) 10 (4.5) 7 (1.4)
Precision Production, Craft, and Repair 18 (9.0) 20 (9.1) 55 (11.4)
Operators, Fabricators, Laborers 23 (11.4) 7 (3.2) 50 (10.4)
Not Employed 51 (25.4) 62 (28.2) 114 (23.6)

 

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9

Table 2.7. Minimum and maximum percent of landowners across all landscapes engaged
in each activity. Minimum percent is based on the number of respondents carrying out a
given activity divided by total survey sample size (N = 1,654). Maximum percent is
based on the number of respondents carrying out a given activity plus the number of non-

respondents (n = 686) divided by the total survey sample size.

 

 

Activity Minimum Maximum
Bird Feeding 38.4 79.9
Bird Houses 26.7 68.2
Plant or Maintain Vegetation 32.0 73.5
Garden 40.1 81.6
Landscape 39.8 81 .3
Fertilize 27.2 68.7
Apply Pesticides or Herbicides 13.9 55.4

 

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96

FIGURE LEGENDS

Figure 2.1. Location of the three BBS routes in Southeastern Michigan where the
landowner survey was conducted. Route 5 3 is Rural, route 167 is Suburban, and
route 168 is Urban. Each BBS route is 39.8 km in length.

Figure 2.2. Frequency distribution of the number of bird feeders per landowner for
landowners that fed birds.

Figure 2.3. Number (A) and density (B) of bird feeders along the three different BBS
routes among landowners that fed birds.

Figure 2.4. Number of landowners feeding birds each month. The three routes are
denoted as follows: Rural (0), Suburban (A). Urban (0), and the total of all routes
(I).

Figure 2.5. Frequency distribution of the number of bird houses per landowner for
landowners that had bird houses.

Figure 2.6. Number (A) and density (B) of bird houses along the three different BBS
routes among landowners that had bird houses.

Figure 2.7. Number of activities each landowner is engaged in by the number of

respondents.

97

 

 

     

 
 

v
1% 0 90 180
1' LR \ \KILOMETERS

URBAN
RURAL [F -

‘ SUBURBAN

 

98

 

Number of Respondents

200

150

100

50

 

 

 

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Number of Bird Feeders per Landowner

99

 

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Rural

Landscape

100

600

500

400

300

200

100

Number of Landowners Feeding Birds

 

 

l l l 1 l l l 1 1 l 1 l

 

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Month

101

 

Number of Respondents

200

150

100

50

 

 

 

 

1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 100 11.0 12.0 135 15.0 19.0 20.0 48.0

Number of Bird Houses per Landowner

102

 

 

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103

Number of Respondents

200

100

50

 

 

 

 

O 1 2 8 4 5 6 7 8

Number of Activities

104

CHAPTER 3

LANDOWNER PERCEPTIONS AND ACTIVITIES RELATED TO BIRDS

ACROSS RURAL-TO-URBAN LANDSCAPES

105

ABSTRACT

Fluctuations of bird abundances in the Eastern and Midwest regions of the United
States have been attributed to such factors as supplemental feeding, landscape
fragmentation, and depredation. Underlying these factors, but notably absent from
consideration, is the role of private landowners. To investigate how landowners perceive
and may influence birds, we surveyed all ~l ,700 private landowners living on three North
American Breeding Bird Survey (BBS) routes (~120 linear km) in Southeastern
Michigan, USA, that represent a continuum of rural-to-urban landscapes. Our survey
assessed both the landowners’ perceptions about birds and the activities in which they
were engaged. Of the 969 (59% response rate) respondents, the typical landowner
indicated that the number of birds frequenting their property had increased over time and
that having bird diversity on their property was very important. Large numbers of
landowners engaged in activities assumed to have positive effects on birds: feeding birds
(66%), providing bird houses (46%), and maintaining vegetation specifically for birds
(54%). A substantial minority, however, engaged in activities with negative implications
for birds: 49% applied fertilizer on their land, 25% applied pesticides or herbicides on
their land, and 26% of landowners had outdoor house cats. While 95% of landowners
were engaged in at least one activity that had possible implications for bird numbers, the
average landowner was only slightly willing to change their land use practices for the
benefit of birds. Overall, landowners who had more favorable perceptions of birds also
tended to engage in a significantly greater number of activities that could have positive

effects on birds. Interestingly, however, landowners’ perceptions of birds were largely

106

unrelated to whether they engaged in activities with negative implications for birds or not.
Across the three landscapes there were significant differences in landowner perceptions
and activities. Our results indicate that landowners tend to perceive birds positively, but
are engaged in a wide variety of positive and negative activities that both intentionally

and unintentionally have profound influences on birds at the landscape scale.

107

INTRODUCTION

Bird populations throughout the Midwest and Eastern portions of the United
States have displayed marked fluctuations in recent decades (Robbins et al., 1989).
These changes have generally been attributed to such interrelated factors as habitat
fragmentation and destruction (Donovan & Flather, 2002), landscape change (Flather &
Sauer, 1996), nest predation (Heske et al., 2001), cowbird parasitization (Robinson et al.,
1995), and direct mortality due to events (e.g., culling by farmers) on the wintering-
grounds of the neotropics (Basili & Temple, 1999). A common denominator underlying
these factors, but notably absent from consideration among the potential mechanisms
responsible for influencing breeding bird abundances, are the landowners that live in the
landscapes being investigated.

Landowners are of particular relevance to understanding bird abundances because
they are the ultimate controllers of their land. As such, landowners’ perceptions of birds
and their land as well as the types of activities they engage in on their land can have
significant repercussions for the birds that frequent or inhabit landscapes containing large
amounts of private land. Furthermore, landowners living in rural landscapes may
perceive both birds and their land differently than landowners in more urbanized
landscapes, or they may carry out activities at different levels. Such differences may in
part explain the substantial variations in bird abundances and diversity often noted along
urban to rural gradients or in urban contexts (Hohtola, 1978; Cam et al., 2000). Because

of the potential for significant landowner effects on birds there has been increased

108

attention directed towards the integration of social components into questions of avian
distributions (Hostetler, 1999).

In directing attention toward how landowners may be influencing avian species it is
important to consider what specific activities landowners may be pursuing on their land.
Arguably, the most important factors to focus on are those that alter or affect the habitat
used by birds or which directly impact birds. These include food and nesting
supplementation, alteration or maintenance of vegetation, introduction of exotic
predators, chemical application, landscaping and gardening, each of which has a known
or strongly suspected relationship to birds.

Aside from understanding the degree to which landowners are involved in
activities on their land, it is also of particular relevance to understand how they perceive
birds. As is noted in social-psychological theory, attitudes toward some object (e.g.,
birds) typically precede actions taken with regard to that object (Ajzen & F ishbein, 1980).
Thus, if landowners perceive birds or their land in positive or environmentally friendly
ways then it follows that they will likely engage in activities that they perceive to
positively influence birds. Furthermore, if landowners have positive perceptions of birds
they may also be more willing to alter their behavior for the benefit of birds.

As part of a larger effort to understand and integrate the social and ecological
factors influencing breeding bird abundances in different types of landscapes (Chapters 1
and 2), we sought to address the role of specific private landowner perceptions and
activities. These perceptions and activities included: perception of changes (if any) in
bird numbers on their property; the importance placed on bird diversity; observation of

the number of birds that occur on the land; willingness to alter land use for the benefit of

109

birds; interest in tax easements or abatements; and participation in feeding birds,
providing bird houses, planting and maintaining vegetation for the benefit of birds,
gardening, landscaping, fertilizing, applying pesticides and herbicides, and allowing
house cats (F elis catus) outdoors. Specifically, we were interested in ascertaining: 1) the
perceptions of landowners; 2) the proportion of landowners involved in each activity; 3)
if differences existed across a rural-to-urban gradient; and, 4) how landowner perceptions
were related to the activities they engaged in that have possible ramifications for bird

numbers.

METHODS

To address our research questions we chose three active North American breeding
bird survey (BBS) routes (routes 53, 167, and 168) in Southeastern Michigan, USA
(Figure 3.1), where >90% of the land is privately owned and undergoing rapid
urbanization (Rutledge & Lepczyk, 2002). We chose these three routes in particular
because they represent a continuum of landscapes from rural to urban, based on their
geographic locations, average land parcel sizes, and socio-demographic compositions.
The landscapes can be classified as Rural (route 53), Suburban (route 167), and Urban
(route 168). In these study landscapes, we identified all private landowners who owned
property immediately adjacent to the road along which the three BBS routes are run. In
addition to personally driving all routes, we utilized county plat maps and tax records,
identifying a total population of 1,694 private landowners (331 on Rural, 390 on

Suburban, and 973 on Urban).

110

We administered a mail survey instrument between October and December of
2000 following the Total Design Method (Dillman, 1978). To encourage responses we
established a toll-free telephone line for landowners to contact us with any questions and
offered prize drawings as an incentive. Briefly, an initial survey was mailed during the
first week of October 2000, followed by a postcard reminder/thank you two weeks later.
Finally, a second survey was sent out two weeks after the postcard to landowners who
had not responded to the prior mailings.

To ascertain what the landowners' attitudes and perceptions were and what
activities they were involved with on their land that could influence bird species we asked
the following questions on our survey: (1) Since you have owned or lived on your
property, do you think that the number of birds visiting it during the summer months has:
(decreased substantially, decreased slightly, stayed about the same, increased slightly,
increased substantially, unsure)? (2) Having a variety of different bird species on or near
your property is: (very unimportant, somewhat unimportant, somewhat important, very
important, unsure)? (3) About how many different bird species are you aware of that live
on or in the vicinity of your property? (4) Would you be willing to change how you use
your land if it would help support bird species (definitely unwilling, possibly unwilling,
possibly willing, definitely willing, unsure)? (5) If the government offered easements or
tax abatements in exchange for preserving your land for birds or wildlife would you be
interested (very disinterested, mildly disinterested, mildly interested, very interested,
unsure)? (6) Does anyone in your household feed birds on your property (yes, no)? (7)
Are there any bird houses on your property (yes, no)? (8) Have you planted vegetation or

maintained landscaping on your property in order to benefit or encourage use by birds

111

(yes, no)? (9) Which of the following activities do you carry out on your land (gardening.
landscaping, fertilizing, spraying pesticides or herbicides)? (10) How many cats does
your household own that are allowed access to the outside? To investigate relationships
between activities and perceptions and attitudes we developed an a priori classification
that divided activities into two groupings based on their suspected impact upon bird
numbers: positive activities consisted of bird feeding, providing bird houses, planting
vegetation, gardening, and landscaping; negative activities consisted of applying
fertilizer, spraying pesticide or herbicide, and allowing house cats outdoors. Participation
in each activity was scored a "1" and non-participation was scored a "0"; each of the two
groupings represents a summation of these separate activity scores (range 0 to 5 for
positive activities; range 0 to 3 for negative activities).

Statistical analyses were performed using SYSTAT 10. We treated any "unsure"
answers, except for number 1 above, as falling in the middle of the scale of answers for
the relevant questions (i.e., 1 to 5, with unsure coded as a 3). Initial comparisons across
landscapes were carried out with ANOVA, using a Bonferonni post hoc test for specific
landscape differences. For landscape comparisons based on the proportion of landowners
engaged in an activity a two-way contingency table with a Pearson Chi-square test was
used. Principal components analysis was used to assess if our a priori classification of
landowner activities matched the reported behaviors of landowners (i.e., did those
reporting a positive activity also tend to report other positive activities and so on).
Relationships between the perception of changes in bird numbers, importance of bird
diversity, willingness to change land use, and interest in tax abatements and positive or

negative activities were analyzed using a forward stepwise general linear model, in which

112

activities were the dependent variables. Specifically, a model was first tested with the
perception versus the activity. If this simple model was significant then the categorical
variable of landscape was added. Similarly, the landscape by perception interaction was
only investigated if the previous route model was found significant. In the case of the
number of different birds that landowners believed occurred on their land relative to their
engagement in positive or negative activities, a linear regression was used, followed by a
general linear model that included landscape if the relationship was significant. Data are
reported as means i SE (as 100% of the population was sampled, but only ~59%
responded), unless otherwise noted, with a p-value of s 0.05 considered significant.

Of the 1,694 landowners initially identified, 40 were removed from consideration
because they were a business or church, had property outside the sampling region, already
responded based on another parcel of land within the study landscapes, or their address
information was incorrect, thus reducing the corrected population size to 1,654. Among
these 1,654 we received 968 completed surveys, yielding a 58.5% response rate.
Response rates per landscape were 64.8% for Rural (212 of 327), 61 .5% for Suburban
(233 of 379), and 55.2% for Urban (523 of 948), which were significantly different ()(22 =

ll.ll,p=0.0039).

RESULTS

While landowners on average believed that the number of birds visiting their
property during the summer months had slightly increased over time, the perception

varied significantly across the three landscapes (Table 3.1). Similarly, having bird

113

diversity on one’s property was viewed as somewhat to very important across all
landscapes, but did vary significantly (Table 3.1). Of the landowners that were aware of
at least one or more bird species living on or near their property, the average respondent
could identify between sixteen and seventeen species; this showed no variation across the
landscapes (Table 3.1). In regards to landowner attitudes towards altering their land for
the benefit of bird species, the average landowner was slightly willing, but this varied
across the landscapes (Table 3.1). Correspondingly, landowners were slightly interested
in tax easements across the landscapes (Table 3.1).

Of the 968 landowners that responded, 95% (n = 920) were involved in at least
one of the eight activities that were measured, with the average landowner engaged in 4.0
;+; 0.06 of the activities. The percent of landowners involved in each activity ranged from
~20% to ~74%, depending upon the activity and the landscape (Table 3.2).
Proportionally, across the landscapes there were significant differences in the number of
landowners that planted vegetation, applied pesticides and herbicides, and allowed their
house cats outdoors (Table 3.2).

A principal components analysis of the activities resulted in three separate
components, with bird feeding. bird houses. planting vegetation and gardening associated
with the first component, fertilizing and applying pesticides or herbicides associated with
the second component, and allowing house cats outdoors associated with the third
component. The activity of landscaping split its loading across the three components. By
considering both components two and three as negative activities for birds, our a priori
categorization, at least in terms of reported participation by landowners, appears to be a

reasonable one.

114

The average landowner was engaged in 3.0 :i: 0.05 positive activities (of a possible
5) and 1.0 i 0.03 negative activities (of a possible 3). Across landscapes no differences
existed in the number of positive activities (F 3‘ 965 = 1.1, p = 0.33), whereas a difference
did exist in the number of negative activities (F 2‘ 965 = 8.7, p = 0.0002). Specifically, the
number of negative activities decreased from the rural landscape to the urban landscape,
with a significant difference existing between both the rural and urban landscapes (p =
0.0005) and the suburban and urban landscapes (p = 0.017).

Landowner perceptions were also statistically related to their participation in the
activities. Landowners who were more likely to perceive increases in bird numbers over
time were also more likely to engage in activities with positive impacts on birds (F 5' 950 =
25.4, p < 0.000001). Likewise, those landowners who felt that bird diversity on their land
was the most important were also those more likely to engage in positive activities (F 4‘ 944
= 50.4, p < 0.000001; Figure 3.2), as were those with greater awareness of different bird
species that live on or near their property (12 = 0.04, p = 0.00001), those who were more
willing to change their land use for the benefit of bird species (F4. 906 = 15.9, p <
0.000001), and, those with greater interest in easements or tax abatements (F 4‘ 937 = 13.6,
p < 0.000001). There was no effect of landscape type (p > 0.05) on these relationships.

In contrast to the positive activities, several different patterns were displayed with
regard to the negative activities. Specifically, landowners who were more likely to
perceive increases in the number of birds on their land were also those more likely to
engage in negative activities (F 5. 9,0 = 5.3, p = 0.00009). However, the perception that
bird diversity was important displayed a non—linear relationship with the number of

negative activities. resulting in a significant relationship (F, 944 = 4.3, p = 0.002; Figure

115

3.2). No relationship existed between (1) the number of birds that landowners were
aware of on their property (r2 = 0.0005, p = 0.6), (2) the interest in changing one’s land
use to benefit birds (F4, 906 = 1.7, p = O. 1), or (3) the interest in tax easements or
abatements (F4. 93., = 1.6. p = 0.2), relative to the number of negative activities that the
landowners’ were engaged in. Both of the significant relationships reported above were
significantly different across the three landscapes (F2. 952 = 7.8, p = 0.0004, for changes in
the number of birds on one’s land; F4, 942 = 4.6, p = 0.001 for importance of bird

diversity), but displayed no interaction (p > 0.05) with landscape.

DISCUSSION

Landowners, in general, tended to perceive birds in a positive manner. For
instance, the majority of landowners believed that the number of birds frequenting their
land had increased over time and that bird diversity was somewhat to very important
(Table 3.1). Similarly, landowners expressed a slight interest in both altering their land
use for the benefit of birds and accepting tax easements or abatements for such change
(Table 3.1). Aside from perceiving birds positively, landowners also engaged in an
average of four activities (of a possible eight) that can potentially influence birds. The
most predominant activities were gardening, landscaping, and bird feeding (Table 3.2).
Notably, however, every activity was engaged in by >25% of the landowners (Table 3.2),
indicating that cumulatively across a landscape the landowner activities are likely great

enough to influence bird abundances and populations. For example, the 25% of

116

landowners that applied pesticides or herbicides may be influencing the invertebrate food
sources that a number of bird species rely upon (Brickle et al., 2000).

The relationships between landowner perceptions and activities displayed several
interesting tendencies. Landowners that perceived higher numbers of birds over time,
were aware of more species, held more positive attitudes about bird diversity, and were
more willing to change their land use or accept tax easements were all also engaged in a
greater number of the positive activities (e. g., Figure 3.2). However, our findings were
substantially more ambivalent with regard to participation in negative activities. Only
two of the perceptions showed any relationship to participation in negative activities:
perception of the change in bird numbers and the importance of bird diversity.
Interestingly, the more a landowner perceived increases in bird numbers, the more likely
were they also to engage in activities that could possibly negatively affect those numbers.
The relationship between landowner evaluation of bird diversity and participation in
negative activities was likewise interesting, revealing no straightforward (albeit
statistically positive) connection between the two. One likely explanation for these
findings might be that even negative activities result in a landowner being outdoors and
actively engaged in observing changes on their land and the species that frequent it.
While a similar line of reasoning could be used with the positive activities, it should be
noted that all of these activities (except general landscaping and gardening, which were
not specifically asked with reference to birds) are deliberately done to benefit birds.
Thus, it is unlikely that landowners first engaged in these activities prior to having
specific perceptions about birds; rather they likely began to engage in the positive

activities as a result of their positive perceptions.

117

Across the rural-to-urban continuum of landscapes there were marked differences,
both in terms of perceptions (Table 3.1) and activities (Table 3.2). Rural landowners
indicated that bird numbers changed to a larger degree than did the landowners in the
other two landscapes. Conversely, rural landowners placed a lower level of importance
on bird diversity and were less willing to alter their land use relative to suburban
landowners. Rural landowners were also more likely to engage in specific activities than
were suburban and urban landowners: planting vegetation, applying fertilizer, and
applying pesticides/herbicides (Table 3.2). It is noteworthy that two of these activities
have potentially quite negative ramifications for bird species.

Overall, our results indicate that landowners perceive birds positively and are
engaged in a host of activities that can directly and indirectly influence avian populations.
A relatively strong association between attitude and behavior was detected for the
positive activities, indicating the potential for providing landowners with educational
information that promotes positive behavior in regards to birds. Finally, our findings
highlight the urgent need for inclusion of private lands as part of the research agenda in
wildlife, avian, and landscape ecology. Because public agencies and private
organizations are increasingly encouraging private land management our findings are
particularly timely as they point to the need to assess the cumulative repercussions of

activities carried out by numerous individual landowners.

118

ACKNOWLEDGMENTS

We would like to thank the Ingham, Livingston, Oakland, and Washtenaw county
Equalization Offices; Kimberly Baker; Daniel Brown; Jayson Egeler; Jane Fallon;
Katherine Gross; Robert Holsman; Nan Johnson; Mike Mascarenhas; Keith Pardieck;
Sam Riffell; and Patricia Soranno. Support provided by Michigan Agricultural
Experiment Station, N.S.F. CAREER Award, MSU. College of Social Science, and a

U .S. E.P.A. Science To Achieve Results Fellowship (Grant no. U-91580101-0).

REFERENCES

Ajzen, I. & Fishbein, M. (1980) Understanding Attitudes and Predicting Social
Behavior, Prentice-Hall, New Jersey.

Basili, G.D. &. Temple, S.A. (1999) Dickcissels and crop damage in Venezuela:
Defining the problem with ecological models. Ecological Applications 9:732-739.

Brickle, N.W.; Harper, D.G.C.; Aebischer, NJ. & Cockayne, S.H. (2000) Effects of
agricultural intensification on the breeding success of corn buntings Miliaria
calandra. Journal of Applied Ecology 37 :742-755.

Cam, E.; Nichols, J.D.; Sauer, J.R.; Hines, J.E. & Flather, CH. (2000) Relative
species richness and community completeness: birds and urbanization in the Mid-
Atlantic states. Ecological Applications 10: 1 196-1210.

Dillman, D.A. (1978) Mail and Telephone Surveys: The Total Design Method, Wiley-

lnterscience, New York.

119

Donovan, T.M. & Flather, CH. (2002) Relationships among North American songbird
trends, habitat fragmentation, and landscape occupancy. Ecological Applications
12:364-3 74.

Flather, C.H. & Sauer, JR. (1996) Using landscape ecology to test hypotheses about
large-scale abundance patterns in migratory birds. Ecology 77:28-35.

Heske, E.J.; Robinson, S.K. & Brawn, J.D. (2001) Nest predation and neotropical
migrant songbirds: piecing together the fragments. Wildlife Society Bulletin
29:52-61.

Hohtola, E. (1978) Differential changes in bird community structure with urbanisation: a
study in Central Finland. Ornis Scandinavica 9:94-100.

Hostetler, M. (1999) Scale, birds, and human decisions: a potential for integrative
research in urban ecosystems. Landscape and Urban Planning 45:15-19.
Robbins, C.S.; Sauer, J.R.; Greenberg, R.S. & Droege, S. (1989) Population declines
in North American birds that migrate to the neotropics. Proceedings of the

National Academy of Sciences of the United States of A merica 86:7658-7662.

Robinson, S.K.; Thomposon III, F .R.; Donovan, T.M.; Whitehead D.R. & F aaborg,
J. (1995) Regional forest fragmentation and the nesting success of migratory
birds. Science 267 : 1987-1 990.

Rutledge, D.T. & Lepczyk, C.A. (2002) Landscape change: Patterns, effects, and
implications for adaptive management of wildlife resources. J. Liu and W.W.
Taylor (Eds). Integrating Landscape Ecology into Natural Resources

Management, Cambridge University Press, Cambridge 312-333.

120

 

 

 

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121

Table 3.2. Percent of landowners involved in each activity across landscapes. P-value is

based on x2 test statistic.

 

 

 

Landscape

Rural Suburban Urban Total p-value
Bird Feeding 64.6 67.4 65.2 65.6 0.80
Bird Houses 45.8 50.6 44.2 45.7 0.26
Plant Vegetation 59.9 57.9 51.1 54.6 0.047
Garden 76.5 71.0 72.0 72.7 0.38
Landscape 68.4 73.7 73.2 72.3 0.39
Fertilize 49.5 48.7 49.6 49.3 0.97
Pesticide/Herbicide 36.7 27.2 19.7 25 .2 0.00002
Outdoor Cats 33.5 32.2 20.5 26.] 0.00007

 

122

FIGURE LEGENDS

Figure 3.1. Locations of the three landscapes (each 39.4 km) in southeast Michigan,
USA, where survey was conducted.
Figure 3.2. The importance of bird diversity versus the number of activities landowners

engage in. Larger scores indicate greater importance of diversity.

123

 

 

    

  

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124

 

MEAN # OF ACTIVITIES

 

 

O POSITIVE ACTIVITIES
C NEGATIVE ACTIVITIES

I I I 1 1

 

1 2 8 4 5
IMPORTANCE OF BIRD DIVERSITY

125

 

CHAPTER 4

BIRD DIVERSITY ACROSS A LANDSCAPE: INTEGRATING AND COMPARING

PUBLISHED DATA WITH LANDOWNER OBSERVATIONS

126

ABSTRACT

Knowledge of bird diversity across a landscape is important not just for natural
historians and omithologists, but also for use in answering many ecological and
conservation questions. Numerous public data sets exist that provide presence/absence
information on species occurrences, but no single one captures all the diversity. As a
means to develop a complete species occurrence list for an urbanizing landscape in
Southeastern Michigan, I combined the existing data of four public and private
organizations, all officially documented rare birds, and surveyed ~1,700 landowners. The
specific goals were to (1) develop a complete list of species occurrences across a
landscape, (2) ascertain what percent of the total species pool landowners could
collectively identify, (3) identify species that had not been noted in the census data sets,
but could be corroborated, and (4) compare the percent overlap among different bird
censuses. The resulting list comprised 289 bird species, which is 30% greater than any of
the single existing lists. Landowners identified 171 bird species (~60%) and had >50%
overlap with all existing databases. In addition, landowners identified five species not
previously noted in existing lists, but corroborated in the literature. The percent overlap
of species across the five different lists ranged from 35% to 67%, with the differences
stemming largely from different protocols. Overall, the findings highlight the need to use
multiple data sources for establishing a list of potential species occurrence as well as the

importance that landowners can play in providing bird occurrence data.

127

INTRODUCTION

Understanding the overall bird diversity across a landscape is important not just
for natural historians and omithologists, but also for use in answering many ecological
questions and developing conservation plans. In numerous landscapes throughout North
America there exists a wealth of information on what bird species occur on or in the
vicinity of a landscape. This existing information is in such forms as the Christmas Bird
Counts (CBC), the North American Breeding Bird Survey (BBS), state lists of rare birds,
and state breeding bird atlases. Notably, however, each of the existing forms of
information may only provide a partial list of species that can occur on a landscape over
time, due to the fact that they are only interested in breeding species (e. g., state breeding
bird atlases), only collect species information near roads (e.g., BBS), or may collect
information at a time of the year that misses a number of migratory species (e.g., CBC).
Because the habitat on a landscape is important not only to breeding species, but also to
species that migrate through it, use it as a stopover site, or accidently occur on it (e.g., due
to inclement weather), establishing a complete list of all potential species occurrences is
essential.

As a means to develop an overall bird diversity list across a landscape I sought to
incorporate both existing bird census data as well as to utilize observations of landowners
that live on the landscape. Specifically my goals were to: 1) develop a complete list of
species occurrences across a landscape that is facing rapid urbanization; 2) ascertain what
percent of the total species pool landowners could collectively identify; 3) identify

species that had previously not been noted in the census data sets, but could be

128

corroborated; and, 4) compare the percent overlap among different bird surveys and

censuses across a landscape.

METHODS

To address the research goals, and as part of a larger investigation on landowner
effects on birds (Lepczyk et al. 2002, Chapters 1, 2, and 3), I focused on landowners
living along three active BBS routes (route numbers 53, 167., and 168) in a heterogeneous
and human dominated landscape undergoing rapid urbanization (see Rutledge 2000 and
Rutledge and Lepczyk 2002 for complete landscape details) in Southeastern Michigan,
United States. In selecting landowners to whom the survey would be administered, I
chose all private landowners that owned property immediately adjacent to the road along
which each of the three BBS routes are conducted. I identified all private landowners
using a three-tiered approach. First, I drove all routes and recorded addresses (either from
the mail box or from the house). Second, I identified all possible landowners living
adjacent to the roads using the most recent plat maps available for each county. Third, I
identified all parcels of land adjacent to the roads using tax records from each county’s
equalization office. Utilizing these three approaches I identified a total of 1,694 private
landowners (331 on route 53, 390 on route 167, and 973 on route 168).

1 administered the survey instrument between October and December of 2000
following the Total Design Method (Dillman 1978). The survey instrument and
procedures were fully evaluated for ethical appropriateness by the Michigan State

University Committee on Research Involving Human Subjects prior to mailing. To

129

encourage responses I established a toll-free telephone line for landowners to contact us
with any questions and offered prize drawings as an incentive. Briefly, an initial survey
was mailed during the first week of October 2000 (Appendix A and B). A postcard
reminder/thank you was sent out two weeks later (Appendix C). Finally, a second survey
was sent out two weeks after the postcard (Appendix D).

Any survey returned from a church, business or public land owner was removed
from the sample. Similarly, surveys that were returned as undeliverable by the United
States Postal Service (USPS), where the recipient was deceased, or where different
landowners had the same address as another landowner and were returned as
undeliverable by the USPS, were removed from the sample. Surveys received after
December 31, 2000 were not included in any analyses. If landowners owned multiple
parcels that were not connected to one another then they were asked to complete the
survey in relation to only one of the parcels. Consequently, in the case of isolated multi-
parcel landowners our methodology is a conservative estimate of landowner knowledge.
However, if the landowner owned multiple parcels that were all contiguous with one
another then they were asked to fill out the survey in relation to the entire block of land.
Surveys that were returned blank (i.e., not filled out) or contained notes indicating no
interest in participating in the survey were considered a non-response. Similarly,
landowners that called to indicate they were unable or had no desire to participate in the
survey were considered non-respondents. Non-respondents are included in the final
corrected sample size.

To ascertain what bird species landowners had observed on their property I asked

the following two questions: 1) “Can you name any of the bird species you typically see

130

on your property (two check boxes: yes or no)?”, and 2) “If “Yes,” please write down the
names of the species observed.” The open-ended question format was used to avoid
leading the respondents in what species they had encountered on their property.

To ensure data quality I edited the landowner responses as follows. All spelling
and grammatical mistakes were corrected and incomplete names that had only one
possibility were completed (e.g., Cardinal became Northern Cardinal). If a landowner
used an antiquated species name (e.g., Baltimore Oriole changed to Northern Oriole) or
colloquial wording (e. g., Sparrow Hawk changed to American Kestrel) it was converted
to currently accepted nomenclature. Incomplete wording, from which no distinct species
or taxonomic group could be discerned (e.g., the word “black” could not be discerned as
any species) were removed. Similarly, if a species was listed that no: 1) field guides (e.g.,
Sibley 2000) indicated to be even remotely in the proximity of the study area; 2) existing
data set concurred with; 3) literature search could confirm; 4) personal observation could
be made; or, 5) records existed from the Michigan Bird Records Committee (MBRC),
then it was removed from the list. Finally, if two or more species could be assumed from
the response, I excluded it from consideration.

Four existing data sets were acquired to develop a complete species list and
compare species occurrences on the landscape. These data sets were, the Michigan
Breeding Bird Atlas (Brewer et al. 1991), all active and inactive routes of the North
American Breeding Survey (routes: 53, 66, 67, 68, 167, 168), all Christmas Bird Count
circles (routes: Ann Arbor, Detroit, Hartford, Pontiac, Waterford, Waterloo State
Recreation Area, Ypsilanti), and all bird occurrences published in The Birds of

Washtenaw County, Michigan (Kielb et al. 1992). Only data that contained complete

131

common or species names from these four data sets was used for analysis. Escaped and
exotic species noted in the different surveys were included in the list and subsequent
analyses. Species occurrences listed in the four data sets that were suspect, due to both
rarity and lack of acceptable confirmation with the MBRC were included in the overall
bird list, but were excluded from the corrected and comparative lists. In the case of rare
birds documented by the MBRC that occur within the landscape, but not found in any of
the existing surveys, I included them only in the overall bird list. All scientific and
common names that had changed over time were updated to currently accepted AOU

terminology.

RESULTS

The total combined number of birds observed on the landscape comprising the
five data sets and the MBRC was 294 (Table 4.1). However, five species, Barnacle
Goose (Branta leucopsis), California Gull (Larus californicus), Chuck-will‘s-widow

(Caprimulgus cgolinensis), Three-toed Woodpecker (Picoides tridacglus), and

 

Tricolored Heron (Egretta tricolor), that were identified in the four published data sets,
are likely either misprints or outside of the study area as the records could not be verified
by MBRC, thus reducing the total corrected diversity to 289 species. Of the 289 species,
23 were identified only in the MBRC, yielding a total of 266 for comparison between
surveys.

A total of 968 (58.6% response rate) landowners responded to the survey, of

which 834 (86.2%) identified at least one bird species that frequented their land (for

132

survey response details see Lepczyk et al. 2002, Chapters 1, 2, and 3). Collectively, the
landowners identified 171 species of birds, comprising 58.2%, 59.2%, and 64.3% of the
full, corrected, and comparative lists, respectively. Notably, landowners identified four
species that did not occur in any of the four published surveys, but were corroborated by
the MBRC. These were the American Magpie Pica hudsonia), Barn Owl (1m Lba),
Bohemian Waxwing (Bombvcilla garrulus), and Summer Tanager (Bjr_an_g_a ELLE).

Of the comparative species list (i.e., 266 species), the number that the other four
surveys recorded were: 124 (44.9%) along the BBS routes, 148 (53.6%) in the CBC
circles, 220 (79.7%) seen in Washtenaw county, and 198 (71.7%) in the Michigan
Breeding Bird Atlas (Table 4.1). The number and percent of species that overlapped each

method ranged from 35.0% to 67.2% (Table 4.2).

DISCUSSION

Overall, by combining all available data sets and the landowner responses resulted
in a species occurrence list that was at least 30% greater than any single previous
estimate. This substantially larger list is likely due to several factors. First, the different
censuses were carried out at different times during the year, thus picking up species that
only occur or pass through the landscape during a specific part of the year. Second,
because of the nature of the survey locations there are inherent habitat biases. For
instance, BBS routes are very unlikely to capture such birds as forest interior specialists.
Finally, each census method or database has been established for different reasons,

thereby having a narrower scope of birds that it focuses on (e.g., MIBBA). However, the

133

>30% increase over the list established in The Birds of Washtenaw Coung, Michigan
(Kielb et al. 1992) is somewhat surprising as this list does incorporate both rare species
and non-breeding species occurrences. Moreover, all the species that made up the extra
30%, except the American Magpie, Barn Owl, Bohemian Waxwing, and Summer
Tanager, were noted in the three state, federal, or Audubon data sets. As a result, this
finding alone highlights the need for integrating multiple species occurrence databases for
establishing a complete species list across a landscape or region. Integrating multiple
databases into a single species occurrence list can also be highlighted by the fact that
while there was a moderate level of species overlap (Table 4.2) across databases, the
percent overlap did not exceed ~66%. The difference in percent overlap is most certainly
due to differences in the timing and methodology of censusing (e.g., summer vs. winter).
For instance, Christmas Bird Counts are conducted in December, during which time the
migrant breeding species captured by the BBS are almost assuredly gone.

Collectively the landowners were able to identify >50% of the species listed in
each database and were able to identify nearly 60% of the potential species. Moreover,
while several species listed by landowners were excluded because they could not be
corroborated, (e.g., Common Raven, Corvus corax), they did report five species that had
only previously been noted by the MBRC. Although a number of bird species that
landowners identified were excluded in the present study due to lack of corroborating
evidence, they could potentially serve to identify locations on the landscape where more
in-depth investigations or follow-up surveys could take place.

Surveying landowners and people in regard to bird species and bird activities has

been a commonly used technique to gain information (Cowie and Hinsley 1988,

134

Brittingham and Temple 1989, Dunn and Tessaglia 1994). Although surveying people in

regards to bird activities and abundances provides a wealth of information, one potential
drawback of many previous surveys is that they target a very narrow group of people.
Specifically, nearly all previous surveys have either been administered to amateur birders,
omithologists, or people who participated in these activities (e.g., Brittingham and
Temple 1989, Wiedner and Kerlinger 1990), or otherwise have sought volunteers (e.g.,

Project Feeder Watch; Wells et al. 1998). As a result these methodologies may be biased
towards only people who are interested in or research birds. Thus, one potential benefit of
the results and method utilized in this study is that it aimed at a geographical location and
not a specific group of people. In addition, conducting surveys of landowners can
potentially provide more information on bird occurrences and abundances in landscapes
that have a predominance of private lands. A final benefit is that surveying a general
populace can provide information on new species occurrences across a landscape, thus

allowing for more targeted censuses by trained omithologists to corroborate the sightings.

ACKNOWLEDGMENTS

I would like to thank the staff at the Ingham, Livingston, Oakland, and
Washtenaw county Equalization Offices, which allowed me access to landowner records.
Keith Pardieck and Jane Fallon at the USGS Patuxent Wildlife Research Center who
kindly assisted with providing maps and details of BBS routes. Kathy Dale assisted with
data use questions related to the CBC. A special thanks goes to Adam Byme from the

Michigan Bird Records Committee for reviewing the bird data and providing MBRC

135

records. I am grateful to Kimberly Baker, Jayson Egeler, Mike Mascarenhas, and Jessica
Schwarz for assisting with the survey logistics and data entry. Robert Holsman, Angela
Mertig, and Sam Riffell provided critical review of the draft survey. Adam Byme, Daniel
Brown, Katherine Gross, Nan Johnson, Sam Riffell and Patricia Soranno critically
reviewed the manuscript and provided many helpfiil suggestions. Support for this
research was provided by a Michigan Agricultural Experiment Station grant and an
N.S.F. CAREER Award to J. Liu and a US. E.P.A. Science To Achieve Results (STAR)
Fellowship (Grant no. U-91580101-0) to C.A. Lepczyk. This paper was submitted in
partial fulfillment of the requirements for C.A. Lepczyk’s doctoral degree in Fisheries and
Wildlife, and the Program in Ecology, Evolutionary Biology, and Behavior at Michigan

State University.

LITERATURE CITED

Brewer, R., G.A. McPeek, and RI. Adams, Jr. 1991. The Atlas of Breeding Birds of
Michigan. Michigan State University Press, East Lansing, MI.

Brittingham, M.C., and S.A. Temple. 1986. A survey of avian mortality at winter feeders.
Wildlife Society Bulletin, 14:445-450.

Brittingham, M.C., and S.A. Temple. 1989. Patterns of feeder use by Wisconsin birds: a
survey of WSO members. The Passenger Pigeon, 51:321-324.

Cowie, R.J., and S.A. Hinsley. 1988. The provision of food and the use of bird feeders in

suburban gardens. Bird Study, 35:163-168.

136

Dillman, D.A. 1978. Mail and Telephone Surveys: The Total Design Method. Wiley-
lnterscience, New York.

Dunn, E.H., and D.L. Tessaglia. 1994. Predation of birds at feeders in winter. Journal of
Field Ornithology, 65:8-16.

Kielb, M.A., J .M. Swales, and RA. Wolinski. 1992. The Birds of Washtenaw County,
Michigan. University of Michigan Press, Ann Arbor, MI.

Lepczyk, C .A., AC. Mertig, and J. Liu. Landowners and Cat Predation Across Rural-to-
Urban Landscapes. Revised and resubmitted to Biological Conservation.

Rutledge, D.T., and C.A. Lepczyk. 2002. Landscape change: Patterns, effects, and
implications for adaptive management of wildlife resources. Pages 312-333 in J.
Liu and W.W. Taylor, editors. Integrating Landscape Ecology into Natural
Resources Management. Cambridge University Press, Cambridge.

Sibley, D.A. 2000. The Sibley Guide to Birds. Knopf, New York.

Wells, J .V., K.V. Rosenberg, E.H. Dunn, D.L. Tessaglia-Hymes, and A.A. Dhondt. 1998.
Feeder counts as indicators of spatial and temporal variation in winter abundance
of resident birds. Journal of Field Ornithology, 69:577-586.

Wiedner, D., and P. Kerlinger. 1990. Economics of birding: A national survey of active

birders. American Birds, 44:209-213.

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Table 4.2. Comparison of all survey/counts with all possible combinations. The number
of species in common is the number of species present in both lists being compared, with

the number in parentheses representing the percent.

 

 

Routes Compared Number of Species in Common
Landowners vs. BBS 103 (53.6%)
Landowners vs. CBC 116 (57.1%)
Landowners vs. BOW 157 (67.1%)
Landowners vs. MIBBA 134 (57.0%)
BBS vs. CBC 71 (35.3%)
BBS vs. BOW 115 (50.2%)
BBS vs. MIBBA 118 (57.8%)
CBC vs. BOW 134 (57.3%)
CBC vs. MIBBA 107 (44.8%)
BOW vs. MIBBA 168 (67.2%)

 

156

CHAPTER 5

THE HUMAN INFLUENCE ON BIRDS ACROSS LANDSCAPES

157

ABSTRACT

Bird populations across the United States have been exhibiting notable
fluctuations, both positive and negative, over the past 30 years. While a host of
mechanisms have been put forth to explain the causes of the fluctuations, the ultimate
factor is generally human influence. However, there has been a paucity of research
investigating the influence of humans across multiple landscapes and regions. To address
this paucity we investigated two human influences, the total area of anthropogenic land
cover and the number of housing units, in relation to avian species diversity and the
trends of 12 species occupying landscapes across the entire Midwest of the United States.
We hypothesized that (1) species diversity would be maximum at intermediate levels of
human influence, based on intermediate disturbance theory; (2) the amount of human
influence should affect the proportion of individuals from the global population of each
of the 12 species occupying each landscape; and, (3) if birds do display a relationship
with anthropogenic land cover and the number of housing units, then those species that
can utilize the supplemental food and shelter as well as escape predation, should have
greater population trends than species that cannot utilize these resources. Across the
entire Midwest a negative relationship existed between avian diversity and both the total
number of housing units and the total amount of anthropogenic land cover, with the latter
having a greater effect. Ten of the twelve species investigated displayed weak to strong
relationships with the level of human influence, but differed between the two measures
(housing units and anthropogenic land cover). No significant differences existed

between the relationship a species exhibited with regard to the total number of housing

158

units and the total amount of anthropogenic land cover based upon major diet or nesting
location. Overall, results indicate that humans are having a significant influence on bird
populations, but that they are not dependent upon natural history factors of diet type and

nest location.

159

INTRODUCTION

Throughout the United States bird populations have undergone marked declines
and fluctuations over the past 30 years. In fact, current estimates indicate that over 25%
(204) of the bird species in the US. have declining populations (Audubon 2002),
including several Neotropical migrants and forest breeding bird species. In the
Midwestern and Eastern portion of the US, these population declines have been
attributed to a host of interrelated factors, including habitat fragmentation and loss
(Robbins et al. 1989, F ahrig 1997, Askins 2000, Donovan and Flather 2002), nest
predation (see Heske et al. 2001 for review), cowbird parasitization (Robinson et al.
1995), and increased mortality on the wintering-grounds (Rappole and McDonald 1994,
Basili and Temple 1999). Notably, however, while many bird species are experiencing
population declines, others are exhibiting large population increases. For instance, in
Michigan the populations of American Crow (Corvus brachvrhvnchos) have increased
nearly 2% per year over the past twenty years (Ray Adams, personal communications,
Sauer et al. 2001). Along similar lines of reasoning for population declines, there are a
number of interrelated factors responsible for these increases, including supplemental
feeding (Brittingham and Temple 1988, Doherty and Grubb 2002), and increased amount
of edge habitat. Although both population increases and decreases have been attributed
to a wide number of proximate causes, in most cases the underlying ultimate influence is
humans.

Because humans influence nearly every ecosystem on the planet (Vitousek et al.

1997), they are increasingly being recognized as important components of the ecosystem

160

(McDonnell and Pickett 1993, Liu et al. 1999, Liu et al. 2001). Concomitant with this

increased recognition of the human component has been a recent increase in the research
directed towards addressing how humans’ influence bird species. Such research covers a

gamut of topics, ranging from the subtle effects (sensu Russell 1993) of repeated human

intrusions into bird habitat (Gutzwiller et al. 1997, Gutzwiller et al. 2002) to the influence
of urbanization (see Marzluff 2001 for review). However, with rare exception, these
studies have been at relatively fine scales (Miller et al. 2001) or only considered a small
number of landscapes. While these fine scale studies have provided critical details
elucidating the factors that influence population parameters such as survival and
fecundity, they have not addressed the larger scale issue of human influences on bird
species across multiple landscapes. Given the fact that the US. population is expected to
increase by 65 million people between 1995 and 2025 (Fischer and Heilig 1997), coupled
with the historical trend towards population decentralization resulting in urban and rural
sprawl, it is essential to understand human influences on birds across multiple landscapes

in order to improve conservation efforts.

Two separate, but interrelated, human influences that have been demonstrated to
affect birds at local scales, but have not been investigated across multiple landscapes are
the influence of landowner activities and the level of human domination of the landscape.
1n the case of landowner activities, this refers to the actions taken by private landowners
on their property that can directly, or indirectly, influence birds, such as supplemental
feeding and housing, application of chemicals, and modification of vegetation. Taken
cumulatively across a landscape these landowner activities can result in a significant
source of impact on bird populations. For example, in three Southeastern Michigan
landscapes, it was found that over 65% of landowners fed birds and nearly half had bird
houses (Lepczyk et al. 2002, Chapter 2). Moreover, while the landowners in the three

landscapes displayed some variation in levels of participation, they all had a very large

161

proportion of the total landowner population involved in the activities. Because of these
high activities levels, birds that can utilize the positive benefits of habitat modification,
such as supplemental food and nesting locations, may have increasing or stable

populations. F urtherrnore, birds that can use bird houses or nest higher in the canopy may

escape the negative effects of increased predation due to house cats. On the other hand,
the level of human domination across a landscape is simply a measure of the degree to
which human influence is present on the landscape. Because human influence can be
measured in a number of ways, human domination can include such factors as the amount
of land cover devoted to human use. the human population size and its spatial
distribution, number of roads, etc.

As part of a larger effort to understand the human influence on breeding birds
(Lepczyk et al. 2002, Chapter 1, 2, and 3), we sought to investigate how the level of
human domination across landscapes influences avian diversity as well as different
foraging and nesting guilds of birds. Specifically, we were interested in: l) determining
how avian diversity changes in relation to two measures of human domination,
anthropogenic land cover and housing units; and, 2) comparing the population trends of
12 specific bird species based on anthropogenic land cover and housing unit number. We
selected anthropogenic land cover and housing units as a general measure of human land
use across landscapes, which while related, are in fact different. Specifically,
anthropogenic land cover is a general measure of anthropogenic land cover and land use
classes, whereas housing units are a measure of physical structures on the landscape,
portions of which are often obscured in maps that have any forested areas (Radeloff et al.

2002). Furthermore, bird abundance and behavior may be quite different in relation to

162

anthropogenic land cover and housing units, as people can directly affect birds near their
housing unit (Chapters 1, 2, and 3).

To investigate the aforementioned relationships, we formulated 3 a priori
hypotheses. First, because human domination or impacts to the landscape are a form of
disturbance we hypothesize that the relationship between avian diversity and both
anthropogenic land cover and housing units should form a hump-shaped (inverse
quadratic) curve. Our basis for a hump-shaped relationship is that completely natural and
completely anthropogenic landscapes are likely to have fewer species than at an
intermediate level where anthropogenic factors may be encouraging a greater number and
mixture of habitats. Hump-shaped relationships of species diversity are relatively
common along productivity gradients and there is evidence that such relationships occur
along other gradients in ecology (Mittelbach et al. 2001). Second, we hypothesize that
the proportion of individuals from a given species occupying a particular landscape, out
of the total population, will be functionally related to the amount of anthropogenic land
cover and number of housing units. This second hypothesis is based on recent research
which found that the proportion of individuals occupying a given landscape, from the
total population, are related to the amount of fragmentation occurring in the landscape
(Donovan and Flather 2002). Furthermore, because previous investigations (Lepczyk et
al. 2002, Chapter 1 and 2) have found that across landscape private landowners are
supplementing food and shelter, as well as introducing exotic predators (i.e., house cats)
and applying pesticides, that species should respond differentially based on natural
history characteristics. Thus, our third hypothesis is that if birds do display a relationship

with anthropogenic land cover and the number of housing units, then those species that

163

can utilize the supplemental food and shelter as well as escape predation, should have
greater relative abundances than species that cannot utilize these resources. Based upon
the third hypothesis, we predicted that with regard to diet, omnivores should have the
greatest population trends, followed by granivores and lastly, insectivores. Similarly, we
predicted that with regard to nesting location, birds that nest in cavities should have the

greatest population trends, followed by canopy, shrub, and ground nesters, respectively.

METHODS

Breeding Bird Survey

Initiated in 1966, the BBS is continental scale roadside survey of breeding birds in
the United States and Canada (Sauer et al. 2001). Surveys are carried out annually along
secondary roads on permanently established routes, each of which is 25 miles (39.4 km)
long. Three-minute point counts are conducted at 0.5 mile (0.8 km) intervals for a total
of 50 point count stops per route. All birds heard or seen within a 0.25 mile (0.4 km)
radius of each stop are recorded. The BBS provides data on avian abundance and is
commonly used for assessments of avian populations trends (e.g., James et al. 1996). We
selected all BBS routes that had been censused a minimum of four times during the 11-
year period of 1987 to 1997 throughout the entire Midwest United States. This ll-year
time period was chosen in order to be centered on 1992, which is the approximate time of
the land cover data (see below). A total of 402 BBS routes, all located in the Midwestern

United States. met these requirements (Figure 5.1).

164

Species Selection

The 12 species selected (Table 5.1) for testing hypothesis two and three were
chosen based first upon diet, then by nesting location. Because humans can directly
supplement both food and nests, these two natural history characteristics may play critical
roles in determining a species abundance in a landscape. Diet categorization was based
on Ehrlich et al. (1988), with the species selected having only one dominant diet grouping
during the breeding season (i.e., no mixed categories, such as insectivore-fi'ugivore, were
considered). The 12 species were chosen to form three equally sized groups of
omnivores, granivores, and insectivores, while at the same time trying to maximize for
differences in nesting location. The four nesting groups, cavity, canopy, shrub, and
ground, were based upon Marin (1995) and Ehrlich et al. (1988). Because there are
relatively few truly omnivorous and granivorous species during the breeding season, this
limited the potential pool of species to nine for granivores and five for omnivores, that

occur in any significant frequency in the Midwest.

Land Cover and Housing Data

The digital National Land Cover Data (N LCD; Vogelmann et al. 2001) from the
United States Geological Survey (USGS) provided the initial land cover and land use data
for the study region. The NLCD data were derived from the early19908 Landsat TM
satellite data and is centered on 1992/93. The database consists of a 21 land cover
classification (Table 5.2) scheme, at 30 m resolution, which was applied consistently over

the US. Data were mapped in Albers Conic Equal Area projection, NAD 83.

165

The 1990 US. Census provided for the first time spatially detailed GIS coverages
on housing density, human populations, and various sociological variables. Recent work
has derived methods to calculate the number of housing units at the partial census block
level for the Midwestern United States (Radeloff et al. 2000, 2001, 2002, Hammer et al.
2002). Housing units, which include houses, condominiums, and apartment buildings,
are a more refined and relevant measure of human impacts than simply human
population, as housing units are now increasing at a faster rate than population (Liu et al.
2003). Moreover, housing units take physical space on the land and are relatively

permanent fixtures.

Landscape Analysis

To characterize the landscape surrounding each BBS route, a circular scene with a
19.7 km radius centered on the route (~1200 kmz) was clipped from both the NLCD
landscape data and US. Census housing data (Flather and Sauer 1996, Donovan and
F lather 2002). This 19.7 km radius circular landscape was chosen to ensure that each
landscape completely contained the BBS route. Subsequently, the NLCD data for each
BBS route (hereafter termed landscape) were reclassified into the three broad classes

79 6‘

“water, anthropogenic,” and “natural,” land cover based upon their major land cover
and land use descriptions of the source classes (Table 5.2). While arguably there are few,
if any, locations in the Midwest that could be considered totally “natural” (Sanderson et
a1. 2002), the intent of classification was to broadly describe the landscapes relative to

human impact. All landscape data operations were conducted using ArcInfo geographic

information systems (GIS) and Erdas Imagine.

166

We used APACK (Mladenoff and DeZonia 2001) to estimate landscape structure
metrics in the reclassified NLCD data for each landscape. Housing unit data was
summarized for all partial census blocks in each landscape. Because of the circular
nature of the landscapes, any partial census block that occurred at the edge of a landscape
was included in the overall estimate. The landscape and housing unit metrics describe
both the amount and arrangement of the anthropogenic factors in each landscape, of
which our primary interest was the amount. Because a number of the metrics are
associated with one another, they have a strong potential for collinearity. Thus, we first
selected four primary landscape metrics: total anthropogenic land cover, mean
anthropogenic patch size, total number of housing units, and mean number of housing
units per partial census block, with the goal of selecting one land cover metric and one
housing unit metric that were least correlated with one another. The two metrics that
displayed the lowest degree of correlation were total amount of anthropogenic land cover
and total number of housing units (Pearson correlation test; X2 = 3.60; df = l; p = 0.06).
Hence, the total amount of anthropogenic land cover and total number of housing units

were selected for the two metrics of human influence on the landscape.

Statistical Analyses ofBreeding Bird Data Across the Landscapes

For the measurement of total species richness (defined as the number of unique
species), the total number of species observed on each BBS route across all years
measured was calculated. Linear and non-linear regression analyses were used in order to
test whether a relationship existed between species diversity and (1) total number of

housing units and (2) total amount of anthropogenic land cover. The two regression

167

techniques were used to establish whether a relationship existed, and then if it were better
described by a simple linear model or an inverse quadratic model, thereby establishing
support for a hump-shaped relationship.

The mean number of individuals for each of the 12 selected species (Table 5.1) on
each route was determined first by selecting only the routes which had reported the
species for a minimum of four censuses during the 1987 to 1997 time period. If a species
occurred for a minimum of four censuses, a mean count of the individuals was taken over
all years the species was present during the l 1-year period for the route. Routes on which
a species occurred in less than four censuses were eliminated from the analysis. The
mean count of individuals for each bird species was smnmed across the landscapes and
the proportion of individuals along each route was determined by dividing the mean count
of individuals per route by the total count of individuals across all routes. The proportion
of individuals of each species occupying each landscape was then regressed against the
(1) total number of housing units and (2) total amount of anthropogenic land cover. All
species displaying a significant relationship were then analyzed together by comparing
the slopes of their relationships with the categorical variables of diet type and nest
location using ANOVA, with a Bonferroni post-hoc test (Zar 1996), to investigate if their
trends were related to these categories. The proportion of individuals on each route was
arcsine square root transformed and the total number of housing units was log
transformed to normalize the data (Sokal and Rohlf 1981).

Population trend estimates for the twelve species were also computed across the
Fish and Wildlife Service Region 3, which corresponds to the eight state area of this

study. from 1987 to 1997 using a route-regression approach (Geissler and Sauer 1990.

168

Sauer et al. 2001) that measures the percent change per year and weights the overall
average according to the number of individual routes, while accounting for observer and
other biases (Sauer et al. 1994). Significant trend estimates based on the entire region
were similarly analyzed against the categorical variables of diet and nest. All statistical

analyses were performed using SYSTAT 10 (SPSS 2000).

RESULTS

The landscape surrounding the 402 BBS routes exhibited a wide range of total
anthropogenic area, mean anthropogenic patch size, nmnber of anthropogenic patches,
maximum anthropogenic patch size, and number of housing units (Table 5.3).

Bird diversity across landscapes displayed a weak, but significant, negative linear
relationship to the total number of housing units (r2 = 0.053; p < 0.000005; Figure 5.2).
The relationship was not improved with a non-linear analysis (r2 = 0.052). In the case of
total anthropogenic land cover, bird diversity displayed a strong negative relationship (r2
= 0.434; p < 0.000005; Figure 5.3). However, the relationship was not improved with a
non-linear analysis (r2 = 0.27).

The proportion of individuals occupying landscapes with different numbers of
housing units displayed significant trends in ten of the twelve species (Table 5.4, Figure
5.4). Of the nine species showing a significant relationship, four displayed a negative
relationship with increasing numbers of housing units and five displayed a positive
relationship with increasing numbers of housing units (Table 5.4, Figure 5.4). Similarly,

the proportion of individuals occupying landscapes with different amounts of

169

anthropogenic land cover displayed a significant relationship in ten of the twelve species
(Table 5.5, Figure 5.5). Likewise, of the ten species showing a significant relationship,
five displayed a negative relationship with increasing amounts of anthropogenic land
cover and five displayed a positive relationship with increasing amounts of anthropogenic
land cover (Table 5.5, Figure 5.5). Notably, the two species, American Goldfinch and
House Finch, whose abundance was not related to anthropogenic land cover were
different than the three species, American Crow, White-breasted Nuthatch, and Yellow
Warbler, that showed no relationship with the number of housing units. Across the entire
Midwest 11 of the 12 species displayed significant positive or negative population trends
(Table 5.6). Of these 11 significant trends, six populations were declining and five were
increasing.

The ten species that displayed a significant relationship with regard to the total
number of housing units (Table 5.4) did not have significantly different slopes based
upon diet (F = 0.95; df= 2, 7; p = 0.43) or nesting location (F = 1.56; df= 3, 6;p = 0.29).
Similarly, the ten species that displayed a significant relationship with regard to the total
amount of anthropogenic land cover (Table 5.5) did not have significantly different slopes
based upon diet (F = 2.91; df= 2, 7; p = 0.12) or nesting location (F = 0.11; df= 3, 6; p =
0.95). Finally, the ten species that displayed significant population trends across the
entire Midwest (Table 5.6) did not have significantly different population trends based
upon diet (F = 2.09; df= 2, 7;p = 0.19) or nesting location (F = 0.92; df= 3, 6;p = 0.48).
While no significant differences existed based upon diet, granivorous birds were the only
one of the three groups that displayed a consistent trend in relation to human influence

and Midwest population trend, which was positive. Again, while not significant, only

170

one nesting location category, canopy, displayed a consistent trend among all three

analyses, which was positive.

DISCUSSION

In the Midwest US. declines in avian diversity are correlated with increases in
both the number of housing units present on the landscape (Figure 5.2) and the total
amount of anthropogenic land cover (Figure 5.3). However, the declines did not
correspond any better to an inverse quadratic function than a linear fianction at the scale
of the study and in relation to the type of disturbance investigated. Thus our first
hypothesis that avian diversity would be greatest at intermediate levels of disturbance was
not supported. While a negative relationship existed with both measures of human
influence, the total amount of anthropogenic land cover showed a much stronger fit to the
avian diversity data (r2 = 0.434; Figure 5.3) than did the total number of housing units (12
= 0.053; Figure 5.2). Several possible reasons exist for this marked difference between
the two measures. First, housing units could both positively and negatively influence the
occurrence of birds near them, depending upon what types of activities the landowners
are engaged in and what type of land cover surrounds them. Specifically, if the
landowners across the entire Midwest are engaged in quite different levels of activities,
there may be several different relationships in the data that have been obscured. In other
words, both positive and negative relationships in bird diversity related to housing unit
number may be occurring due to differential levels of activities that may positively and

negatively influence bird abundances, which could ultimately result in little if any overall

171

pattern. Second, anthropogenic land cover may simply be a more robust measure of
overall human influence than the number of housing units present on a landscape. A
final reason may simply be that the number of housing units is too course of a measure
across such large landscapes.

Overall, the abundance of bird species was related to anthropogenic land cover
and the number of housing units, thus supporting the hypothesis that the relative
abundance of a species will be functionally related to the amount of anthropogenic land
cover and number of housing units. However, while a number of species did have
significant relationships, many of them were rather weak. Specifically, although nine of
the twelve bird species displayed significant relationships with regard to the number of
housing units, only three, House Finch, American Goldfinch, and Mourning Dove, had
large r2 values (Table 5.4, Figure 5.4). Similarly, in the case of anthropogenic land cover,
ten of the twelve bird species displayed significant relationships (Table 5.5). Notably,
however, these ten species were different than those found in the housing unit analysis
(Table 5.4 and 5.5). Of the ten species having a significant relationship with the amount
of anthropogenic land cover, only four bird species, Horned Lark, House Wren, Mourning
Dove, and Ovenbird displayed r2 values that suggest a strong correlation. Only Mourning
Doves and Ovenbirds exhibited significant relationships with both measures of human
influence. In the case of both Mourning Doves and the remaining five species that
showed any marked correlation with the human influences, all of them are generally
believed to have strong positive or negative relationships with humans. For instance,
Mourning Doves are readily found at most bird feeders and are more common in cities

and urban areas than in more natural or wild locations. On the other hand, Ovenbirds are

172

an area-sensitive forest interior bird that occurs less frequently in more fragmented
landscapes (Robinson et a1. 1995). Across the entire Midwest, eleven of the twelve
species had significantly increasing or decreasing populations, with only the American
Goldfinch displaying no significant change in its population over the eleven years
investigated (Table 5.6).

Comparing the birds that displayed significant relationships with the two
measures of human influence, as well as those that had significantly increasing or
decreasing population trends across the Midwest, with the natural history categories of
diet and nest location, yielded no significant results. Thus, our hypothesis that diet type
and nest location would be important explanatory factors was not supported. While diet
was not an important explanatory factor, it is notable that the class of granivores was the
only one of the three classes that consistently displayed a positive trend with human
influence and across the entire Midwest. Similarly, in the case of nesting location, only
the canopy nesters displayed a consistent relationship with human influence, and across
the Midwest, which was positive. As a result, while non-significant, the findings of
granvirores and canopy nesters displaying positive relationships with human influence
and across the Midwest suggest that they are best able to survive, and potentially thrive,
in human-dominated landscapes.

Because the total number of housing units and total amount of anthropogenic land
cover measure two different aspects of human influence, and thus may have different
effects on the relative abundance of birds, they were investigated separately. However,
given the rather weak and inconsistent results found by analyzing the two human

in 11 uence factors separately we did investigate their combined effect on relative

173

abundance by carrying out an additional set of analyses using multiple regression. Thus,
while not an a priori hypothesis, we tested to see if both factors together significantly
influenced the relative abundance of each of the twelve species. Utilizing the multiple
regression approach yielded a significant model for each of the twelve species (Table
5.7). While the multiple regressions did improve the r2 estimates for some species, such
as the Blue Jay and Brown Thrasher, they did not improve the r2 estimates for other
species, such as the House Finch or White-breasted Nuthatch, beyond the previous
estimates. Thus, the multiple regressions did improve the relationships between relative
abundance and the human influence factors for some species, but in most cases the
models did not explain the data any further than the separate regression models.
Interestingly, the two species which did exhibit a large increase in their r2 estimates were
the Blue Jay and the Brown Thrasher. In the case of the Blue, it is a species that is
commonly associated with both backyard bird feeders, and hence housing units, as well
as edges and anthropogenic land cover. On the other hand, Brown Thrashers are a
species that have been exhibiting declines throughout the Midwest (Donovan and Flather
2002), and thus may be negatively impacted by both the presence of housing units and the
conversion of natural land cover into anthropogenic land cover.

In general, the results do indicate that bird diversity and abundance across the
landscapes of the Midwest are related to the amount of human influence present on the
landscape. Given the large-scale nature of the analyses and the general metrics used,
these relationships may well be improved with the inclusion of more specific landscape
metrics and natural history data. Similarly, analyzing a larger pool of species with regard

to natural history categories, might result in such factors as diet and nesting location

174

becoming important. Overall, then, the results indicate that humans are having a
significant effect on bird populations, but that they are not dependent upon natural history

relationships.

ACKNOWLEDGMENTS

We would like to thank Jane Fallon at the USGS Patuxent Wildlife Research
Center who kindly assisted with providing maps and details of BBS routes, Marc
Linderman who provided generous assistance with technical issues, Mike Knowles for
assistance with data analysis, and Anna Pidgeon for critical discussion of bird species.
We are grateful to Daniel Brown, Katherine Gross, Nan Johnson, and Patricia Soranno
critically reviewed the manuscript and provided many helpful suggestions. Support for
this research was provided by a Michigan Agricultural Experiment Station grant and an
N.S.F. CAREER Award to J. Liu, a Michigan State University College of Social Science
Grant to J. Liu, A. Mertig, and P. Sorrano, and a US. E.P.A. Science To Achieve Results
(STAR) Fellowship (Grant no. U-91580101-0) to C.A. Lepczyk. This paper was
submitted in partial fulfillment of the requirements for C.A. Lepczyk’s doctoral degree in
Fisheries and Wildlife, and the Program in Ecology, Evolutionary Biology, and Behavior

at Michigan State University.

175

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180

Table 5.1. Bird species selected for population trend analysis.

 

 

 

 

 

 

 

 

 

 

 

Species Diet Nest
American Crow (Corvus brachvrhvnchos) Omnivore Canopy
American Goldfinch (Carduelis tristis) Granivore Shrub
Blue Jay (Cvanocitta cristata) Omnivore Canopy
Brown Thrasher (Toxostoma rufum) Omnivore Shrub
Horned Lark Eremo hila M) Granivore Ground
House Finch (Carpodacus mexicanus) Granivore Canopy
House Wren (Troglodytes aedon) Insectivore Cavity
Mourning Dove (Zenaida macroura) Granivore Canopy
Ovenbird (Seiurus aurocapillus) Insectivore Ground
Red-headed Woodpecker (Melanerpes erythrocephalus) Omnivore Cavity
White-breasted Nuthatch (§i_t_ta_ carolinensis) Insectivore Cavity
Yellow Warbler (Dendroica petechia) Insectivore Canopy

 

 

181

Table 5.2. NLCD land cover classes.

 

 

Class Name Subclass Code Recode
Water open 1 1 water
ice and snow 12 water
Developed low intensity residential 21 human
high intensity residential 22 human
commercial/industrial/transportation 23 human
Barren bare rock/sand/clay 31 natural
quarries/strip mines/gravel pits 32 human
transitional 33 natural
Forested Uplands deciduous 41 natural
evergreen 42 natural
mixed 43 natural
Shrubland Shrubland 5 1 natural
Non-natural Woody orchards/vineyards/other 61 human
Herbaceous Upland grasslands/herbaceous 71 natural
Herbaceous Planted and pasture/hay 81 human
Cultivated
row crops 82 human
small grains 83 human
fallow 84 human
urban/recreational grasses 85 human
Wetlands woody 9 1 natural
emergent herbaceous 92 natural

 

182

 

 

 

 

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183

Table 5.4. Regression analysis of proportion of individuals occupying a landscape

relative to the total number of housing units.

 

 

Species 11 slope r2 p-value
American Crow 397 0.003 0.009 0.064
American Goldfinch 398 0.01 0.10 <0.0000005
Blue Jay 400 0.004 0.017 0.009
Brown Thrasher 346 -0.009 0.056 0.000008
Horned Lark 290 -0.01 0.02 0.016
House Finch 223 0.039 0.29 <0.0000005
House Wren 354 0.006 0.022 0.004
Mourning Dove 387 0.013 0.13 <0.0000005
Ovenbird 160 -0.034 0.14 0.000001
Red-headed Woodpecker 240 -0.016 0.08 0.000007
White-breasted Nuthatch 270 0.001 0.0007 0.66
Yellow Warbler 281 -0.0006 0.0001 0.84

 

184

Table 5.5. Regression analysis of proportion of individuals occupying a landscape

relative to total amount of anthropogenic land cover.

 

 

Species n slope r2 p-value
American Crow 397 -0.000000054 0.02 0.005
American Goldfinch 398 0.000000016 0.001 0.44
Blue Jay 400 -0.000000104 0.07 <0.0000005
Brown Thrasher 346 0.000000116 0.06 0.00001
Horned Lark 290 0.000000638 0.32 <0.0000005
House Finch 223 0.000000012 0.0001 0.86
House Wren 354 0.000000190 0.11 <0.0000005
Mourning Dove 387 0.000000300 0.4 <0.0000005
Ovenbird 160 -0.000000967 0.53 <0.0000005
Red-headed Woodpecker 240 0.000000118 0.02 0.04
White-breasted Nuthatch 270 -0.000000102 0.04 0.0009
Yellow Warbler 281 -0.000000136 0.02 0.0007

 

185

Table 5.6. Route-regression analyses of all BBS routes across the Midwest region. Note,

sample size may be larger than number of landscapes analyzed.

 

 

Species n Trend p-value
American Crow 510 1.77 <0.000005
American Goldfinch 509 0.27 0.53
Blue Jay 51 1 -1.54 0.00002
Brown Thrasher 460 -2.21 0.0003
Horned Lark 373 -l .52 0.04
House Finch 337 17.65 <0.000005
House Wren 457 1.20 0.0004
Mourning Dove 496 -0.61 0.07
Ovenbird 224 1 .56 0.00002
Red-headed Woodpecker 346 -5.99 <0.000005
White-breasted Nuthatch 415 -1.53 0.04
Yellow Warbler 387 3.26 0.00001

 

 

186

Table 5.7. Multiple regression analysis of proportion of individuals occupying a
landscape relative to both the total amount of anthropogenic land cover and the total

number of housing units. Note, in each model the p-value was <0.001.

 

 

Species 11 slope of constant r2
American Crow 397 0.34 0.04
American Goldfinch 398 0.0058 0.11
Blue Jay 400 0.027 0.13
Brown Thrasher 346 0.088 0.15
Horned Lark 290 0.052 0.36
House Finch 223 -0.10 0.29
House Wren 354 0.024 0.12
Mourning Dove 387 -0.0008 0.4
Ovenbird 160 0.12 0.53
Red-headed Woodpecker 240 0.12 0.11
White-breasted Nuthatch 270 0.045 0.05
Yellow Warbler 281 0.05 0.05

 

187

FIGURE LEGENDS

Figure 5.1. Locations of all 402 Breeding Bird Survey (BBS) routes across the Midwest
United States.

Figure 5.2. Total bird diversity (# of species) versus the total number of housing units.

Figure 5.3. Total bird diversity (# of species) versus anthropogenic land cover.

Figure 5.4. Proportion of individuals occupying each landscape versus the total number
of housing units for each of the twelve species.

Figure 5.5. Proportion of individuals occupying each landscape versus the total amount

of anthropogenic land cover for each of the twelve species.

188

 

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190

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193

Total Anthropogenic Land Cover (he)

 

 

 

 

 

SYNTHESIS AND CONCLUSION

A primary objective of the research presented in this dissertation was to
understand the types and magnitudes of activities that landowners engage in on their
property that can influence birds. As evidenced by Chapters One and Two, landowners
are in fact engaged in a wide variety of activities that can both directly and indirectly
influence birds across all landscapes. While the activities investigated were not
exhaustive, the eight investigated are all known to have effects on birds. Furthermore, the
research results presented here provide a set of data on which to base future research
about how private landowners are both intentionally and unintentionally influencing bird
species on or near their property.

Prior to this dissertation research, there were few, if any, publications about
landowner activities that influence birds, aside from several government surveys and gray
literature reports. Thus, one important finding of my research is simply understanding the
degree to which landowners modify and influence their land intentionally for the benefit
of birds. With regard to intentional modifications for the benefit of bird species, the
activities of food and nest supplementation and planting vegetation are being carried out
by approximately 50% or more of the landowners, indicating that cumulatively a very
large proportion of landscape is being intentionally, but independently, managed for bird
species. On the other hand landowners are engaged in a number of activities that have
unintentional implications for bird species. For example, allowing cats outdoors and
applying pesticides and herbicides are two activities that approximately 25% of
landowners engaged in that have negative consequences for birds, which landowners are
in all likelihood not engaged in with any intention of harming bird species. Such
reasoning may in part explain why these negative activities showed no relationship with

how landowners perceive birds on their property.

194

 

Related to what landowners do on their property that can influence bird species, a
second objective of the research was to measure how landowners perceive birds on their
property. Overall, a key finding of landowners’ perceptions presented in Chapter Three
was that the average landowner believed both bird diversity and having birds on one’s
land was important. Although landowners were only slightly interested in tax incentives
or altering their land use for the benefit of birds, their overall positive perception of birds
is a significant finding because it may be an avenue that can be pursued for better
conservation and management of bird species. Landowner perceptions were also
important in that as they increased so too did the number of positive activities that they
engaged in on their land. The results strongly suggest that landowner perceptions about
birds influence the number of positive activities that they engage in on their property.
Again, this positive association indicates that targeting conservation and management
efforts through the use of bird species may be an important aspect to consider.

Landowner perceptions also offer a potential new direction for ascertaining where
species occur on the landscape. Because of the percent of land in private ownership
throughout Southeast Michigan and the Midwest, the use of a mail survey to census bird
species may be a very important tool. As Chapter Four highlights, landowners not only
reported a large diversity of birds across the landscapes, but also identified many rare
species that other surveys had missed. Thus, the use of mail surveys to census birds on
private lands may not only be an important tool for establishing bird abundance data, but
ultimately may prove to be more cost effective than other methods.

The last objective of this dissertation was to utilize the findings from the intensive
landowner surveys on the three BBS routes presented in Chapters One and Two in order
to make assumptions and predictions about bird populations across 402 BBS routes of
the Midwest. The rational for investigating the entire Midwest region was that a large
sample size of BBS routes was needed in order to investigate actual impacts on bird

populations, which could not have been accomplished with only the three original routes.

195

 

Thus, by assuming that the activities occurring along the three BBS routes in
Southeastern Michigan were representative of all landscapes surrounding all 402 BBS
routes in the Midwest, I predicted that both diet type and nest location would be key
explanatory factors in the relationship between human influence and the relative
abundance of birds. The 12 species selected for the analysis based on their diet type and
nesting location exhibited varying degrees of relationships between human influence and
their relative abundance. However the relationships among the birds relative abundance
and level of human influence bore no relationship to either diet type or nest location.
While diet type and nest location were not important explanatory factors, the results
highlight two other key findings. First, bird diversity is related to both measures of
human influence in a negative manner. In other words, as human influence on the
landscape increased bird diversity decreased. Second, the relative abundance of most
individual species investigated in Chapter Five exhibited either a positive or negative
relationship with the degree of human influence present on a landscape, but did not
exhibit a marked increase in the relationship when both measures were considered
together.

As with all research projects there were both limitations and unforseen
shortcomings of the data presented in this dissertation. Although the overall goal of the

dissertation research was to address how landowners influence birds through their

1

behaviors and activities across landscapes and to utilize these findings to make

predictions about bird species across an entire region, it was only partially achieved.

A?"

Originally, an objective of the research was to connect the behaviors of the landowners
along the three BBS routes with the bird abundance data from these routes, in order to
relate changes in bird abundances with landowner activities. While the objective remains
important, the scale at which the research was conducted does not allow for such direct
integration to be made. Specifically, the BBS abundance data at the route level have both

a great deal of variability and are difficult to estimate reliable population trends. As a

196

means to overcome the route level variability and partially integrate the data I made the
assumption that the level of activities found in the three study landscapes of Southeastern
Michigan were similar across the entire Midwest. I based this assumption on both the
high levels of landowner activities across the three Southeastern Michigan landscapes and
the results from recent Fish and Wildlife Service surveys of wildlife recreation that
indicate a large portion of the Midwest population engages in feeding and watching birds.
However, for future work an alternative method would be to greatly increase the number
of BBS routes that are surveyed and simply sample fewer, but representative, landowners
along a each route. Moreover, by increasing the number of BBS routes and decreasing
the landowner sample size per route, broader conclusions about landowner activities
could be made. Such increases in sampling would also allow for better comparative and
predictive power across multiple landscapes.

A second limitation of this dissertation research is in the amount of detail obtained
from the landowner survey. Because the overall goal of the survey was to obtain many
general pieces of data about private landowners and their influence on birds a tradeoff
was made between very specific details on a few topics or less detail on a greater number
of topics. I selected the latter perspective largely because of how little information exists
about private landowners and their influence on bird species. Thus, many pieces of

information were somewhat unexpected, such as the fact that 55% of landowners planted

“T51

or maintained vegetation for the benefit of birds. However, as the research indicates,

each activity or perception could, and should, be explored in far greater depth. .4 ..
A related limitation of the landowner survey is that it may be a biased measure of

landowners. Obviously any methodology has a bias and it certainly is possible that the

landowners who responded to the survey had a particular like or interest in birds.

However, even if the survey was biased towards bird enthusiasts, the overall response rate

of ~59% indicates that non-respondents do not need to be engaged in the activities in

order for birds to be influenced on a large proportion of the landscape.

197

 

The limitations of the research were not only present in the landowner survey
work, but were also present in the Midwest BBS analysis. Because the original objective
was to connect landowner activities with bird abundances, I utilized the results from the
landowner survey to make general predictions across all Midwest BBS routes. Although
significant relationships were found between both bird diversity and the relative
abundance of selected species with increased levels of human influence, no relationships
were found in regard to nest location or diet type. Notably, however, many of the
significant relationships were not very strong as interpreted by their r2 values. A number
of reasons can be offered as to why significant relationships were not found with regard
to diet type and nest location, as well as with regard to the relative abundance analyses.
First, the landscapes used for the analysis may themselves be biased in that they are
circular rather than linear. As a result patches and houses that are far away from the BBS
routes have an equal influence as those that lie directly on the BBS routes. Second, the
study area for the research questions was based on a political boundary of the eight
Midwest states, which does not follow any direct ecological boundary. Hence, the
species investigated in the analyses may have shown different relationships if they were
analyzed according to ecoregion or other ecological unit of analysis. Third, the species
selected for the analysis were chosen based purely on their diet type and nest location, not
on any known relationships with land cover or human influence. Thus, had the species
been selected using additional criteria the results may well have been different. Similarly,
had larger samples of species been selected for each natural history categories significant
differences may have resulted.

Because the research presented in this dissertation addresses many data poor areas
of ecology, there are perhaps more questions that have arisen from it than have been
answered. Moreover, because the methodology used for the research did not allow for a
direct coupling between landowners and the birds present on the three BBS routes of

Southeastern Michigan, these types of questions are even more important now. To build

198

upon the work presented here requires addressing other topics and questions, such as

those presented below:

1) What are the population consequences for birds when landowners allow their
cats outdoors?

2) Is conservation education having any effect in reducing the number of outdoor
and feral cats?

3) What are the motivations for landowners to engage in each of the activities on
their property and do they consider the effects of the activities on birds or other
wildlife species?

4) Do landowner activities interact with one another such that there are synergistic
effects of multiple activities?

5) How do landowner activities and perceptions vary across a wider gradient of
landscape types?

6) Are different levels of landowner activities related to differences in community
composition of birds?

7) Does the cumulative sampling of landowners for the presence of birds on their
land exhibit a similar relationship as a species-area curve?

8) Would diet type and nest location become important natural history categories r.-
if more species were investigated or a different geographical boundary was used?
9) How does the interaction of multiple human factors affect bird populations .5.
across different ecoregions?

10) Are there any natural history factors, such as body size or clutch size, that are
important covariates in the relationship between bird abundance and human

influence?

199

These ten questions which I have posed are by no means exhaustive. In fact each
question, I hope, raises many more questions and interesting avenues of research to
pursue. However, as the ten questions demonstrate, there are many challenges that
remain as ecologists continue to integrate the human component into their research.
Although the findings of this dissertation are but a first step in trying to integrate and
synthesize people with landscapes, a number of important results were found.

Overall, the major finding of this dissertation research is that humans are, for
better or worse, directly or indirectly, intentionally or unintentionally, influencing birds
and the landscapes they live in. While the magnitudes may differ across landscapes, the
simple fact remains that humans are having impacts on bird species. It is worth pointing
out, however, that most individual landowners have little to no interest in negatively
impacting bird species. Barring several pest species (e.g., House Sparrows or American
Crows), landowners by and large are intentionally involved in a number of activities
which they believe will positively influence birds. Thus, collectively, a number of
activities that landowners engage in may very well benefit birds. The question remains,
though, are these activities benefiting a relatively few number of species at a cost to other
species that may have been present if the activities had not been conducted? Only by
continuing to integrate the human component into ecological research can we answer this,
and many other important ecological questions noted above. Ultimately, the work
presented here provides an initial stepping stone upon which future research into the

relationships between humans, bird populations, and landscapes can be built.

200

 

APPENDIX A

201

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APPENDIX B

 

 

 

210

MICHIGAN STATE UNIVERSITY

 

DEPARTMENT OF FISHERIES AND
WILDLIFE

13 NATURAL RESOURCES BUILDING
EAST LANSING . MICHIGAN . 48824-1222
(517) 355-4477

FAX (517) 432-1699

October 3, 2000

«NAME»
«ADDRESS_I»
«CITY», «STATE» «ZIP»

Dear «NAME»:

You have been selected to participate in a research study that is exploring relationships between bird
populations and land use in Southeastern Michigan. You were selected because you live or own property
along or near «ROAD», in «CO» County, Michigan. Along this road is a monitoring route used to count
the number of birds living in Michigan. We are particularly interested in learning about bird populations
near your property. For this reason, we are asking for about IO to 20 minutes of your time to complete the
enclosed questionnaire regarding birds and land use in your area. As a resident or landowner, your input on
issues involving land use is very important. Since we want to gather information that represents all
residents and landowners in your area, your response is vital for the success of our project.

This survey is intended for the person in your household, ownership group, or trust who is at least 18
years of age and who makes most of the decisions regarding your land. If the person to whom this is
addressed does not fit this description, please give this survey to a person in your household, ownership
group, or trust who does. If you do not currently reside or own land as described above, we would
appreciate it if you could return the survey to us with a note indicating this fact. If you received more than
one survey--which could occur if you own more than one parcel of land within the area specified above--
you should only fill out and return one of the surveys.

While your response to this questionnaire and any of the questions is completely voluntary, we feel that
these issues are important enough to warrant contacting you. You indicate your voluntary agreement to
participate by completing and returning the questionnaire. You may be assured of complete confidentiality.
The survey has identifying information for mailing purposes only. This is so that we may check your name
off of the mailing list when your survey is returned and also allows us to place your name in a prize
drawing (see below). Your name and address will never be associated with your responses in any way.
Your privacy will be protected to the maximum extent allowable by law.

For your convenience, we have included a postage-paid envelope for returning the survey. All surveys
completed and returned by October 31", 2000 will be entered into a drawing for a $100 gift
certificate to Meijer. If you cannot respond by October 31St we would still like to receive your survey as
soon after that as possible so we can include your information in our results. I would be happy to answer
any questions you might have. Feel free to call me toll free at l-877-745-7288. Thank you for your
assistance. Your contribution to the success of this study will be greatly appreciated.

Sincerely.

Christopher A. Lepczyk

211

APPENDIX C

212

Dear Friend:

You were recently sent a questionnaire concerning bird populations and land use in
Southeastern Michigan. If you have returned the questionnaire, thank you. If you have
not yet completed the questionnaire, please take a few minutes to do so now. Your input
is very important for understanding Michigan’s birds.

Sincerely,

Christopher Lepczyk

Project Coordinator

Department of Fisheries and Wildlife
Michigan State University

13 Natural Resources Building

East Lansing, MI 48824-1222

 

1-877-745-7288 (Toll Free)
Dear Friend:

213

APPENDIX D

 

 

214

 

MICHIGAN STATE UNIVERSITY

DEPARTMENT OF FISHERIES AND WILDLIFE
13 NATURAL RESOURCES BUILDING

EAST LANSING . MICHIGAN . 48824-1222

(517) 355-4477

FAX (517) 432-1699

November 3, 2000

«NAME»

«ADDRESS_1 »
«PO_BOX»

«CITY», «STATE» «ZIP»

Dear «NAME»:

A few weeks ago you were mailed a survey about “Michigan Birds on the Landscape.” As of today, we
have not received your completed survey. If this letter and your completed survey have crossed in the mail,
we would like to thank you for returning your survey. If you have not yet filled out the survey, we hope
you will take the opportunity to do so now. We are sending another survey, along with a stamped return
envelope, to make it easier for you to respond.

Michigan contains a highly diverse set of bird species. In order to understand how these bird species use
different areas of Southeastern Michigan, it is essential that we hear from you. You were selected because
you live or own property along or near «ROAD», in «CO» County, Michigan. Along this road is a
monitoring route used to count the number of birds living in Michigan. Because this survey is being sent to
relatively few people in Southeastern Michigan and because we need the results to represent all residents, it
is very important that each person respond to this survey. We are interested in everyone’s opinion. It does
not matter what your age is, how much property you own, or if you live on your property—your
opinions are valued. If you truly have no opinion on an issue, feel free to indicate that on the survey—but
we Still need your response in order to know this.

This survey is intended for the person in your household, ownership group, or trust who is at least 18 years
of age and who makes most of the decisions regarding your land. If the person to whom this is addressed
does not fit this description, please forward this survey to a person in your household who does. If you do
not currently own or live on the property described, we would appreciate it if you could return the survey to
us with a note indicating this fact.

You indicate your voluntary agreement to participate in this survey by completing and returning this
questionnaire. You may be assured of complete confidentiality. The survey has an identification number
that allows us to check your name off of the mailing list when your survey is returned. Your name and
address will never be associated with your responses in any way.

If you respond by November 17, 2000, your name will be entered into a new prize drawing to receive a
$50 gift certificate to K-Mart. I would be more than happy to answer any questions you may have. Feel
free to call me toll free at l-877-745-7288. Thank you for your assistance—it is greatly appreciated.
Sincerely,

Christopher A. Lepczyk
Project Manager

215

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