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BOBCAT (LYNX RUFUS) ECOLOGY IN A LONGLEAF PINE ECOSYSTEM IN
SOUTHWESTERN GEORGIA
by
JORDONA DOUGHTY
(Under the Direction of Robert J. Warren)
ABSTRACT
A paucity of knowledge exists about the effects of northern bobwhite (quail; Colinus
virginianus) management practices on bobcat (Lynx rufus) ecology. Quail management is an
important part of the longleaf pine (Pinus palustris)-wiregrass (Aristida stricta) ecosystem. This
study investigated bobcat home range, habitat use, and dietary patterns in a longleaf pine-
wiregrass ecosystem managed for quail in southwestern Georgia. Male home ranges were larger
than female home ranges, and home range sizes varied seasonally for females, but not for males.
Bobcats selected habitats to include in their home range, but did not select habitats within the
home range. Agriculture was the most preferred habitat type, and edge was an important
component of habitat. Diet varied seasonally during year 1 and year 2, but not during year 3.
Bobcats were not a major predator of quail. Their primary prey items were cotton rats
(Sigmodon hispidus) and other rodents. Land management practices such as prescribed burning
and maintenance of food plots probably contributed to high quality habitat with ample prey; thus
certain quail management practices may impact bobcat ecology.
INDEX WORDS: bobcat, diet, habitat use, home range, longleaf pine, Lynx rufus, scat, southwestern Georgia
BOBCAT (LYNX RUFUS) ECOLOGY IN A LONGLEAF PINE ECOSYSTEM IN
SOUTHWESTERN GEORGIA
by
JORDONA DOUGHTY
B.S., University of Delaware, 2002
A Thesis Submitted to the Graduate Faculty of The University of Georgia in Partial Fulfillment
of the Requirements for the Degree
MASTER OF SCIENCE
ATHENS, GEORGIA
2004
© 2004
Jordona Doughty
All Rights Reserved
BOBCAT (LYNX RUFUS) ECOLOGY IN A LONGLEAF PINE ECOSYSTEM IN
SOUTHWESTERN GEORGIA
by
JORDONA DOUGHTY
Major Professor: Robert J. Warren
Committee: L. Michael Conner Steven B. Castleberry Ronald L. Hendrick
Electronic Version Approved: Maureen Grasso Dean of the Graduate School The University of Georgia December 2004
iv
But the wildest of all the wild animals was the Cat.
He walked by himself, and all places were alike to him.
--Rudyard Kipling, Just So Stories
v
ACKNOWLEDGEMENTS
I would first like to extend my deepest gratitude to my co-major professors, Dr. Robert
Warren and Dr. Mike Conner. I am very lucky to have worked with such wonderful mentors.
Dr. Warren, your enthusiasm and sense of humor were always encouraging, and your advice
about my project, coursework, thesis-writing, and job-searching was well-taken. Dr. Conner,
without your statistical expertise, my data analysis would not have been possible. Your
instruction in trapping, editorial comments on every draft of every thesis chapter, assistance in
the job hunt, and everything else you helped me get through are all greatly appreciated. I would
also like to thank my other committee members, Dr. Steven Castleberry and Dr. Ron Hendrick,
for input on my thesis.
There are many people at Ichauway who helped make the bobcat project possible since
its inception almost 4 years ago. Thank you to Ivy Godbois for essentially setting up all of the
field components of the project. Although I arrived at Ichauway well into the project, many
thanks go out to Jerry Wade, Raymond Varnum, Brad Cross, and Brandon Rutledge for all of the
trapping they did early on and before I arrived. Thank you to Bobby Bass for setting up scat
lines and retrieving animals that meandered over to the Longleaf Plantation. I would also like to
thank Bobby for being a good friend and always putting a smile on my face. Thanks to Mark
Melvin for keeping us updated on bobcats he trapped off-site and for always inquiring about my
fitness progress. Thanks to Arthur Sheffield and the other guys at the shop for always keeping
Black Mud up and running, one headlight and all.
vi
Without the help of the Wildlife Lab at Ichauway, there would have been fewer bobcats
radio-tracked. Micah Perkins, Amanda Subalusky, and Brent Howze helped capture quite a few
animals before I arrived. I would like to give an extra thanks to Brent for helping me with
trapping, for always keeping on the lookout for scat, and for giving me a good laugh during
many conversations in the lab. Thanks to Allison Reid, who threw herself into trapping during
the short time she was here. Without her extensive recapture efforts, many bobcats would have
been lost to radio-collar failure.
I would not have survived fieldwork and getting through my project without the guidance
and friendship of Jessica Cochrane. Thanks JCC, for showing me all of the ropes of telemetry,
trapping, work-up of bobcats, etc. Thank you too, for keeping my mom at ease by
accompanying me on all of my night runs, well after you were done with telemetry duty (lol).
Without your kindness, I never would have legally driven again! Your friendship is one I will
never forget.
Thank you to many friends who always kept me encouraged. Marsha Ward and Justin
Davis were my personal cheerleaders, even though they were 4 hours away. I would especially
like to thank Marsha for being one of the best friends I could ever have, without whose
friendship I ever would have made it living in Georgia. Thanks to my roommates, Tara Muenz,
Allison Reid, and Sarah Cathey, for being good friends and always asking how things were
going. Tara and Allison never complained when I made coffee or breakfast at 2 or 3 a.m., trying
to be as quiet as possible and ending up making a huge racket. I would also like to thank all of
my hometown and college friends who spent long hours on the phone giving me encouragement
when I needed it most. Thank you to Ron, Angela, and Kim Kirby, my second family, for
providing support and love when I was miles away from my own family.
vii
Although they think I am crazy, my family has finally accepted that I am working
towards my dreams. Without the love and support of my parents, I never would have gone after
my goals or succeeded this far in my life. Thanks Mom, for being so incredibly overprotective
that I wanted to scream, but also for letting me become my own person just the same. Dad, I am
so thankful for your cheerful outlook and enthusiasm for everything I do. Thank you to my sister
Taylor, who is already following in my footsteps and who keeps me greatly entertained.
Someday, Taylor, you'll have your horse and we can ride together. I would really like to thank
Steven, my brother, whose friendship and respect mean the world to me. I hope you know that I
am as proud of you as you are of me. Thank you to all of my family for your encouragement,
even when you didn't quite understand what I am doing and why I do it. I will just keep showing
you the pretty pictures.
I would like to give a special thanks to my fiancé, Brian Kirby, for his admiration,
support, love, and understanding during my project. Thanks for staying up half the night on
Friday to do telemetry after a long drive from Rincon, and for getting up early on weekends to
run traps with us. You always put me high up on a pedestal, even when I didn't think I belonged
there. I can only hope I will be as patient during your Master's work as you have been with me.
I can't express to you how glad I am that we didn't give up on each other.
The Joseph W. Jones Ecological Research Center, the Robert Woodruff Foundation, and
the University of Georgia provided financial support for the project. Vehicles were provided by
the Georgia Department of Natural Resources. Thank you for Black Mud, she's a great truck!
Again, Thank you to everyone!
viii
TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS.............................................................................................................v
LIST OF TABLES...........................................................................................................................x
LIST OF FIGURES ....................................................................................................................... iv
CHAPTER
1 INTRODUCTION, STUDY AREA, JUSTIFICATION, AND THESIS FORMAT ....1
2 BOBCAT HOME RANGES IN A LONGLEAF PINE ECOSYSTEM IN
SOUTHWESTERN GEORGIA..............................................................................23
3 FACTORS AFFECTING BOBCAT HABITAT USE IN A LONGLEAF PINE
ECOSYSTEM IN SOUTHWESTERN GEORGIA................................................43
4 BOBCAT DIETS IN A LONGLEAF PINE ECOSYSTEM IN SOUTHWESTERN
GEORGIA ...............................................................................................................67
5 CONCLUSIONS AND MANAGEMENT IMPLICATIONS.....................................94
APPENDICES .............................................................................................................................104
A MANAGEMENT ZONES ON ICHAUWAY, BAKER COUNTY, GEORGIA, 2000-
2004 .......................................................................................................................104
B MORPHOLOGICAL DATA COLLECTED FOR 50 ADULT BOBCATS
CAPTURED AND RADIO-COLLARED BETWEEN DECEMBER 2000 AND
MAY 2004, ICHAUWAY, BAKER COUNTY, GEORGIA ...............................106
ix
C ANNUAL AND SEASONAL ADAPTIVE KERNEL (ADK) AND MINIMUM
CONVEX POLYGON (MCP) HOME RANGE SIZE ESTIMATES FOR
BOBCATS ON ICHAUWAY, BAKER COUNTY, GEORGIA, 2001-2004 ......109
D DESCRIPTION OF FIVE BOBCAT DENS LOCATED IN A LONGLEAF PINE
ECOSYSTEM, ICHAUWAY, BAKER COUNTY, GEORGIA, 2002-2004 ......116
E DESCRIPTION OF BOBCAT MORTALITIES IN SOUTHWESTERN GEORGIA,
2001-2004..............................................................................................................118
x
LIST OF TABLES
Page
Table 2.1: Studies documenting bobcat home ranges (km2) in the southeastern United States
(MMA=Modified Minimum Area; MCP=Minimum Convex Polygon; ADK=Adaptive
Kernel) ............................................................................................................................42
Table 3.1: Habitat type distance ratios for second-order selection using seasonal home ranges for
female bobcats at Ichauway, Baker County, Georgia, 2001-2004 .................................61
Table 3.2: Habitat rankings based on pair-wise comparisons between habitat type distance ratios
for second-order habitat selection of female bobcats monitored on Ichauway, Baker
County, Georgia, 2001-2004...........................................................................................62
Table 3.3: Habitat type distance ratios for second-order selection using seasonal home ranges for
male bobcats at Ichauway, Baker County, Georgia, 2001-2004.....................................63
Table 3.4: Habitat rankings based on pair-wise comparisons between habitat type distance ratios
for second-order habitat selection of male bobcats monitored on Ichauway, Baker
County, Georgia, 2001-2004...........................................................................................64
Table 3.5: Habitat type distance ratios for third-order selection using seasonal home ranges for
male and female bobcats combined at Ichauway, Baker County, Georgia, 2001-2004 .65
Table 3.6: Habitat rankings based on pair-wise comparisons between habitat type distance ratios
for third-order selection of all bobcats monitored on Ichauway, Baker County, Georgia,
2001-2004 .......................................................................................................................66
xi
Table 4.1: Studies documenting bobcat diet by percent occurrence in the southeastern United
States, using the gastrointestinal tract (GI; stomach or intestines) or scat for analysis ..93
iv
LIST OF FIGURES
Page
Figure 2.1: Seasonal home range sizes for male and female bobcats (F01=Fall 2001;
W02=Winter 2002; S02=Spring 2002; Su02=Summer 2002; F02=Fall 2002;
W03=Winter 2003; S03=Spring 2003; Su03=Summer 2003; F03=Fall 2003;
W04=Winter 2004; S04=Spring 2004) on Ichauway, Baker County, Georgia, 2001-
2004 ...............................................................................................................................40
Figure 4.1: Annual percent occurrence of prey items consumed by bobcats based on scat analysis
on Ichauway, Baker County, Georgia, 2001-2004........................................................83
Figure 4.2: Seasonal percent occurrence of prey items consumed by bobcats based on analysis of
135 scats on Ichauway, Baker County, Georgia, 2001-2002 ........................................85
Figure 4.3: Seasonal percent occurrence of prey items consumed by bobcats based on analysis of
130 scats on Ichauway, Baker County, Georgia, 2002-2003 ........................................87
Figure 4.4: Seasonal percent occurrence of prey items consumed by bobcats based on analysis of
148 scats on Ichauway, Baker County, Georgia, 2003-2004 ........................................89
Figure 4.5: Seasonal percent occurrence of prey items consumed by bobcats (S01=Summer
2001; F01=Fall 2001; W02=Winter 2002; S02=Spring 2002; Su02=Summer 2002;
F02=Fall 2002; W03=Winter 2003; S03=Spring 2003; Su03=Summer 2003; F03=Fall
2003; W04=Winter 2004; S04=Spring 2004) based on analysis of 413 scats on
Ichauway, Baker County, Georgia, 2001-2004.............................................................91
1
CHAPTER 1
INTRODUCTION, STUDY AREA, JUSTIFICATION, AND THESIS FORMAT
2
INTRODUCTION
The mesopredator-release hypothesis predicts that in the absence of apex predators, a
population explosion of medium-sized omnivores, hereafter referred to as mesopredators, will
occur (Rogers and Caro 1998). Apex predators are thought to suppress mesopredators, resulting
in ecosystem stabilization and greater species diversity. Therefore, the presence of apex
predators may increase prey species survival by controlling mesopredator populations
(Palomares et al. 1995, Rogers and Caro 1998, Courchamp et al. 1999, Crooks and Soule 1999,
Henke and Bryant 1999). Lower mesopredator population density results in improved nesting
success in songbirds and game birds through reduced nest predation (Sovada et al. 1995, Rogers
and Caro 1998, Courchamp et al. 1999, Crooks and Soule 1999).
Bobcats (Lynx rufus) are considered an apex predator in certain forested ecosystems of
the southeastern U.S. (Conner et al. 2000). However, control of bobcats and other mammalian
predators is often suggested as a way to increase game bird abundance. Although bobcats
historically have been considered a major predator of northern bobwhite (quail; Colinus
virginianus), few studies have specifically analyzed bobcat food habits in areas managed for
quail.
On 2 quail plantations in southern Alabama, quail were not an important part of bobcat
diets despite a high quail density (Miller and Speake 1978). In fact, the study suggested that
bobcat predation on cotton rats (Sigmodon hispidus) might be beneficial to quail populations by
decreasing nest predation and competition for food plants (Miller and Speake 1978).
3
In southwestern Georgia, quail remains were found in 1.9% of all bobcat scats collected over a 2-
year period (Cochrane 2003). However, a different study of mammalian predators in Georgia
found that quail remains in bobcat diets varied over a 2-year period, ranging from 0% - 12.5% on
1 of the areas studied (Schoch 2003).
A paucity of knowledge exists about the effects of quail management practices on bobcat
ecology, and whether bobcats have detrimental impacts on quail populations. Quail hunting is an
important cultural and economic tradition in the Southeast, and quail management is an
important part of the longleaf pine (Pinus palustris)-wiregrass (Aristida stricta) ecosystem
(Burger et al. 1999, Boring 2001). Thus, determining the impacts of bobcats on quail and the
impacts of quail management on bobcats are important for wildlife managers and researchers.
Home range
The bobcat is a solitary carnivore with variable home range sizes influenced by numerous
factors including geographic region, sex, age, season, habitat quality, prey availability and
abundance, and possibly experience (time-in-residence) (Fendley and Buie 1986, Anderson
1987, Rucker et al. 1989, Sandell 1989, Conner et al. 1999). Bobcats tend to have lower
densities and larger home ranges in the northern parts of their range, which have been related to
climatic/environmental and prey availability differences (Litvaitis et al. 1986, Anderson 1987,
Lovallo and Anderson 1996). Home ranges of bobcats in the Southeast vary from 1.1 km2 for
females and 2.6 km2 for males in Alabama (Miller and Speake 1979) to 24.5 km2 for females and
64.2 km2 for males in Arkansas (Rucker et al. 1989). Estimates of composite bobcat home range
sizes in southwestern Georgia over 2 years were 2.8 + 0.6 km2 for females and 6.0 + 0.8 km2 for
males (Cochrane 2003).
4
Perhaps the most important determinant of bobcat home range size is the association
between habitat quality and prey abundance and availability (Anderson 1987). An inverse
relationship exists between home range size and prey density (Mares et al. 1976, Buie et al.
1979, Knick 1990). According to the bobcat habitat suitability index model, the suitability of
habitat is determined by the ability of the habitat to support prey populations (Boyle and Fendley
1987). Habitats that are more suitable for abundant prey densities are more likely to be included
in a bobcat’s home range.
Generally, male home range sizes exceed those of females by 2-3 times, and may be as
much as 5 times larger (Hall and Newsom 1976, Buie et al. 1979, Kitchings and Story 1979,
Whitaker et al. 1987). Male home range size is affected by the size of female home ranges and
the number of mating opportunities, whereas female home ranges appear to be regulated by
diversity, abundance, stability and distribution of prey populations (Anderson 1987, Sandell
1989). Intrasexual overlap of home ranges, particularly between females, does not occur
frequently in bobcats, but male home ranges may overlap several female home ranges (Marshall
and Jenkins 1966, Hall and Newsom 1976, Buie et al. 1979, Miller and Speake 1979, McCord
and Cordoza 1982, Whitaker et al. 1987).
Size of home range also may be affected by season, though few studies of bobcats in the
Southeast have documented seasonal variation. Males have the largest home range during the
breeding season, and females have the smallest home range during parturition and kitten-rearing
(Anderson 1987). Seasonal fluctuation in home range sizes also may relate to seasonal
differences in prey availability. Home ranges were smallest during the summer in Arkansas,
probably because prey abundance is greatest during the warmest months (Rucker et al. 1989).
5
In southwestern Georgia, home ranges were largest for males during spring and summer
(Cochrane 2003). However, in South Carolina, bobcat home range size did not fluctuate
seasonally (Fendley and Buie 1986).
Only one study has investigated the influence of experience, or time-in-residence, of
bobcats on home range size. In a 5-year study of bobcats in Mississippi, changes in home range
size relative to time-in-residence were sex-dependent (Conner et al. 1999). Male bobcat home
range sizes were smaller in previous-year analysis than in subsequent years, whereas female
home ranges were larger in the previous year compared to subsequent years. Males may increase
their home range as they become well-established in their territories over time, probably to
increase breeding opportunities (Conner et al. 1999). As females establish themselves in an area
and develop hunting skills and familiarity with their home range over time, they will decrease
their home range size, optimize a smaller area, and save energy. Such relationships between sex,
time-in-residence, and home range size are poorly understood, creating a need for further
research.
Habitat Use
Habitat use patterns vary throughout the geographic range of the bobcat, but prey
abundance is the major determinant in habitat selection (Pollack 1951, Anderson 1987, Rucker et
al. 1989). Other factors that influence habitat use include resting site availability, denning site
availability, protection from environmental extremes, dense cover for hunting and escape, and
freedom from disturbance (Pollack 1951, Young 1958, Bailey 1974, Kitchings and Story 1984,
Anderson 1987, Boyle and Fendley 1987). Experience (time-in-residence), activity versus
inactivity, and diurnal versus nocturnal time periods are other potential influences on bobcat
habitat use (Conner et al. 1999).
6
Generally, bobcats prefer early to mid-successional habitats and areas with dense cover or rocky
outcroppings (Young 1958, Hall and Newsom 1976, Miller and Speake 1979, Knowles 1985,
Anderson 1987). Studies have found that bobcats also use human-modified areas, such as
abandoned logging roads, pipelines and old agricultural fields (Hall and Newsom 1976,
Kitchings and Story 1978, Miller and Speake 1979, Rucker et al. 1989).
Bobcat prey in the Southeast, especially the cotton rat and the eastern cottontail
(Sylvilagus floridanus), are most abundant in dense areas of early to mid-successional grass/forb-
shrub vegetation (Boyle and Fendley 1987). The shrub interspersion is necessary to provide
essential cover for prey species (Schnell 1968). Primary prey of bobcats also occurs in high
densities in broomsedge (Andropogon spp.)-vine habitat, characterized by herbaceous species
interspersed with shrubs and shrubby vines such as blackberry (Rubus spp.), Japanese
honeysuckle (Lonicera japonica), and trumpet vine (Bignonia radicans) (Golley et al. 1965).
Prescribed burning is a quail management practice conducive to improving habitat for bobcat
prey species by reducing the amount of woody understory, and promoting an herbaceous
understory.
In the Southeast, habitats selected by bobcats include pine plantations and agricultural
areas (Conner et al. 1992, Cochrane 2003), bottomland hardwoods (Heller and Fendley 1986,
Cochrane 2003), hardwoods associated with drainages in forested uplands (Zwank et al. 1985,
Cochrane 2003), and mid-successional stages with dense growth of saplings, vines and briars in
the bottomland hardwoods (Hall and Newsom 1976). These habitats have more abundant prey
than mature pine forests and other available habitats. Habitat use varies by season and is most
likely in response to seasonal shifts in prey availability and climatic variation (Rolley and Warde
1985). Sex-related differences in habitat use also occur in bobcats.
7
Females use higher quality habitat than males because they require more prey within smaller
home ranges, especially with changing energy demands during kitten-rearing (Rolley and Warde
1985). Den site availability also influences habitat use in females (Bailey 1974).
Experience (time-in-residence) may influence habitat use in bobcats, but only one study
has investigated this relationship. Home range habitat composition did not change relative to
time-in-residence for male or female bobcats in Mississippi, but it seemed to change for males
(Conner et al. 1999). Although differences in habitat use were not detected, more studies of this
potential relationship are necessary. Differences in active versus inactive animals and diurnal
versus nocturnal time periods also may influence habitat use in bobcats, but such influences have
never been investigated.
Dietary Patterns
Predators generally select prey within certain size limits to optimize ease in capture and
energy returns (Rosenzweig 1966, McCord and Cordoza 1982). Bobcats concentrate kills on
prey from 150-5,500 g, including squirrels (Sciurus spp.), pocket gophers (Geomys spp.,
Thomomys spp.), rabbits, large rodents and opossum (Didelphis virginiana)-sized mammals
(Rosenzweig 1966, McCord and Cordoza 1982, Boyle and Fendley 1987). They consume larger
prey, including deer (Odocoileus spp.), less frequently (McCord and Cordoza 1982, Story et al.
1982, Anderson and Lovallo 2003). Bobcats primarily consume rabbits and hares, particularly
cottontail rabbits (Sylvilagus spp.), throughout their range (Anderson 1987). Rodents comprise
the remaining bulk of the diet, though species vary by habitat. Some ground-dwelling avian (i.e.,
game and nongame) and reptilian (i.e., snakes) species also are consumed.
8
Bobcats may exhibit functional responses to prey by switching dietary composition from one
primary prey species to another as the abundance of different species changes (Baker et al.
2001). Bobcats also ingest grass, either accidentally or intentionally as a purgative (Miller and
Speake 1978, Buttrey 1979).
Variation in food habits occurs geographically. In the Southeast, cotton rats and eastern
cottontails compose most of the diet during all seasons, and cotton rats replace eastern cottontails
as the primary prey source when they are more abundant (Beasom and Moore 1977, Miller and
Speake 1978, Boyle and Fendley 1987, Cochrane 2003). White-tailed deer (Odocoileus
virginianus) become an important food source in some southern regions, especially during fall-
winter when carrion from the hunting season is available, and in late spring-summer, when fawns
are available (Buttrey 1979, Story et al. 1982). Deer become an important food source during
periods of low density of preferred prey (Beasom and Moore 1977). In mountainous and
highland regions of the South, squirrels, pine voles (Microtus pinetorum) and some bird species
become important food sources (Buttrey 1979, Kitchings and Story 1979).
Sex and age-related differences in food habits occur based on individual body size of
bobcats. In Arkansas, females consume more rats and mice than males (Fritts and Sealander
1978), and in New Hampshire, males consume more white-tailed deer and fewer cottontails than
females and juveniles (Litvaitis et al. 1984). Such differences in food habits appear to decrease
intraspecific competition within bobcat populations (Rosenzweig 1966, Fritts and Sealander
1978).
9
Reproductive/Den Ecology
Timing of the bobcat reproduction season, comprised of breeding, parturition, and
nursing young, varies according to geographic location, climate, photoperiod and prey
availability (McCord and Cordoza 1982). Breeding begins earlier and continues longer in
southern regions (McCord and Cordoza 1982). In Mississippi, the reproductive season occurs
between 1 January and 30 April (Jackson and Jacobson 1987). The post-parturition period, in
which the female must provide prey to her kittens, occurs between 1 May and 31 August, and
kittens remain with their mother through the fall season, until approximately 31 December
(Jackson and Jacobson 1987).
The location of bobcat den sites appears to be related to prey availability; females are
limited to hunting prey in close proximity to unprotected kittens (Bailey 1979). Den sites have
been discovered in hollow logs, rocky outcrops (Gashwiler et al. 1961, Cochrane 2003), at the
base of tree stumps in timber-harvested areas (Kitchings and Story 1984), and in thickets and
brush piles (Anderson 1987, Cochrane 2003). Den sites in human-made structures, such as
abandoned buildings, also have been observed (Bailey 1974). Auxiliary den sites, used by the
female bobcat and her kittens once they are old enough to travel with her, have been described in
rocky areas and abandoned holes of other species such as the woodchuck (Marmota monax)
(Bailey 1979, Kitchings and Story 1984). Prescribed burning may create thickets and hollow
stumps, thereby increasing the availability of den sites for bobcats (Young 1958, Kitchings and
Story 1984).
10
Longleaf Pine-Wiregrass Ecosystem
The longleaf pine-wiregrass ecosystem historically covered almost 36.5 million ha in the
southeastern United States. Today, this unique, fire-dependent ecosystem exists only in scattered
patches totaling less than 81,000 ha in the Coastal Plains of several southern states. Almost 30%
of remaining longleaf forest is located in Georgia (Holliday 2001). Many remaining tracts of
longleaf pine-wiregrass communities exist on private lands managed for northern bobwhite using
prescribed fire. Only about 3,600 ha of remaining longleaf forest is old-growth, and 1,024 ha of
old-growth is found in Georgia (Holliday 2001). Timber harvesting, development of naval stores
and production of turpentine, and fire suppression associated with land settlement contributed to
such a vast decline of the ecosystem (Engstrom et al. 2001).
Fire is critical to maintaining longleaf pine-wiregrass ecosystems because it reduces
competing hardwood species and woody understory, improves nutrient flow, encourages
regeneration in forest gaps, and induces a flowering response in wiregrass (Engstrom et al.
2001). Many species of plants and animals are considered threatened or endangered in the
longleaf pine-wiregrass ecosystem because they are found only in these declining fire-dependent
communities (Engstrom et al. 2001). The longleaf pine-wiregrass ecosystem has received much
attention in recent years due to its rapid disappearance. Restoration efforts at the public and
private level have been initiated throughout the Southeast. Managing for quail through
prescribed burning contributes to promoting longleaf pine restoration. Thus, research devoted to
quail management practices and their relationship to longleaf pine ecosystems has developed.
11
Quail Management Practices
Typical quail management activities, such as a 2-year rotation prescribed fire, planting
agricultural crops, maintaining food plots, and supplemental feeding, may prove beneficial to
bobcats. Prescribed fire increases and maintains a dense herbaceous understory and early
successional habitat, providing abundant resources and habitat for many small mammals that are
bobcat prey species (Golley et al. 1965, Miller and Speake 1979). Burning also may contribute
to more suitable denning habitat for bobcats by creating thickets and hollow stumps, which are
considered good denning sites (Young 1958, Kitchings and Story 1984).
Planting agricultural crops and maintaining quail food plots increases edge, also
providing greater prey availability for bobcats (Hall and Newsom 1976, Miller and Speake
1978). Food plots are usually agricultural grain patches established as borders between existing
agricultural fields and woods. Supplemental feeding, usually concentrated in feeders or scattered
in low vegetation or existing food plots, causes increased density and decreased home range size
in prey species, potentially attracting more predators (Landers and Mueller 1986, Boutin 1990).
In southwestern Georgia, bobcats were 10 times closer than expected to supplemental food than
expected (Godbois et al. 2004).
STUDY AREA
Ichauway is a privately owned 11,735-ha research facility located in Baker County,
Georgia, 16 km south of Newton, Georgia. It is located in the Dougherty Plain physiographic
province in the southeastern Gulf Coastal Plain (Boring 2001). Ichauway is characterized by flat
to gently rolling karst topography, with elevations ranging from 27 to 61 m. It has hot, humid
summers and short, mild, wet winters, with average daily temperatures ranging from 11.1°C
(winter) to 27.2°C (summer). Average annual precipitation is 132 cm per year (Boring 2001).
12
Longleaf pine woodlands and limesink wetlands are the dominant habitat types at
Ichauway. Other habitats include mixed pine-hardwood areas, food plots, agricultural fields,
slash pine (P. elliottii) flatwoods, riparian hardwood hammocks, oak sandhill barrens, natural
and old-field loblolly pine (P. taeda) stands, grassy and cypress-gum (Taxodium ascendens,
Nyssa biflora) limesink ponds, creek swamps, forested wetlands, riverine areas, shrub-scrub
upland, and human/cultural (i.e., resident quarters) areas (Boring 2001). The understory is
dominated by wiregrass and old-field grasses (e.g., Andropogon spp.), but >1,000 vascular plant
species occur on the site (Goebel et al. 1997, Drew et al. 1998). Approximately 24 km of the
Ichawaynochaway Creek flows through the study area, and the Flint River forms almost 22 km
of Ichauway’s eastern boundary (Boring 2001).
The site is divided into multiple-use and conservation zones interspersed throughout the
land area. Multiple-use zones comprise approximately 60% of Ichauway, and prescribed fire,
supplemental feeding, and maintenance of food plots are the primary management activities in
multiple-use zones. Conservation zones, comprising the remaining 40% of the land area, are
managed for longleaf pine restoration. Bobcats occur in both zones on Ichauway.
Much of Ichauway is managed for the longleaf pine-wiregrass ecosystem with prescribed
fire. Burning is performed on a 2-year rotation, usually during winter and early spring, on
approximately 4,000 to 6,000 ha throughout the entire site (Godbois et al. 2004).
Prescribed burning is used to control understory vegetation, reduce hardwoods, manage wildlife
habitat, reduce fuel buildup, promote wiregrass seed production, prepare sites for pine
regeneration, and for experimental research and educational activities (Boring 2001).
13
Food plots consisting of brown top millet (Brachiaria ramose), winter wheat (Triticum
aestivum), cowpea (Vigna spp.), grain sorghum (Sorghum vulgare), and Egyptian wheat
(Sorghum spp.) comprise 20% of the property (Godbois et al. 2004). Food plots occur less
abundantly in conservation zones than multiple use zones, and are typically planted for white-
tailed deer rather than quail. Supplemental feeding for quail with grain sorghum occurs in
multiple use zones at 2-week intervals between November and May (Godbois et al. 2004).
Fields are disked to improve quail food availability by allowing ragweed (Ambrosia
artemisiifolia) and partridge pea (Chamaecrista fasciculata) seedlings and other plants to grow
(Landers and Mueller 1986, Davis 2001).
Limited predator removal occurs in multiple use zones after the quail-hunting season
(March-May) annually. The primary predators removed are raccoons (Procyon lotor) and
opossums. Low numbers of coyote (Canis latrans), red fox (Vulpes vulpes), gray fox (Urocyon
cinereoargentus), and striped skunk (Mephitis mephitis) also are removed each year. Bobcats
were harvested occasionally before 1999, but since then have not been harvested.
JUSTIFICATION
Quail hunting makes a significant economic impact and it is part of a long-held cultural
tradition in the southeastern United States (Burger et al. 1999). Thus, quail management in the
South is important, and is a component of maintaining fire-dependent, longleaf pine-wiregrass
ecosystems. Because bobcats historically have been considered detrimental to game birds such
as quail through predation on adults and eggs, they often are harvested on quail plantations.
Research documenting the relationship between bobcats and quail is lacking but necessary for
quail plantation managers. Bobcats may be beneficial to quail by reducing populations of quail
predators or competitors.
14
Thus, a study of bobcat ecology in a quail management area is important for both researchers and
managers. Studying the ecology of bobcats in the longleaf pine-wiregrass ecosystem will aid in
future management decisions regarding bobcats in the southeastern U.S. If evidence suggests
that bobcats may have a stabilizing effect in longleaf pine-wiregrass ecosystems by regulating
other predators that may be detrimental to quail, then bobcat conservation may improve
restoration efforts for this threatened ecosystem.
Economic demand for non-endangered bobcat and lynx (Lynx canadensis) in North
America increased in the 1970s after the import of fur of endangered cats was made illegal
through passage of the Endangered Species Conservation Act of 1969 (Anderson 1987).
Between 1970 and 1976, annual harvest of bobcats across the United States increased 3-fold, and
price per pelt rose more than 10 times (Anderson 1987). Bobcats were added to Appendix II of
the Convention on International Trade in Endangered Species (CITES) in 1975 in response to a
rising concern about possible over-exploitation (Anderson 1987, Conner et al. 1992). As a result
of the CITES listing, bobcat research has become important because each state must monitor
populations to ensure that harvest does not prove detrimental to the species (Anderson 1987,
Conner et al. 1992). Because bobcat home range size, density, and habitat use vary
geographically, it is necessary to gather information regarding basic ecology on a regional basis
to make effective management decisions (Rucker et al. 1989, Conner et al. 1992). The ecology
of bobcats in Georgia has only recently been studied.
OBJECTIVES
1. Determine if bobcat home range size varies annually, and by season and sex.
2. Determine bobcat habitat use at 2 spatial scales, and compare bobcat habitat use
between sexes and among seasons.
15
3. Determine whether activity status and time-of-day influence bobcat habitat use.
4. Quantify bobcat diet and determine if it varies seasonally and annually.
THESIS FORMAT
The thesis was written in manuscript format. Chapters 2, 3, and 4 represent manuscripts
to be submitted for publication. Chapter 1 is an introduction to the thesis and summarizes prior
research of bobcat ecology. Chapter 2 describes bobcat home ranges in the longleaf pine-
wiregrass ecosystem and will be submitted to the American Midland Naturalist. Chapter 3
describes bobcat habitat use and will be submitted to the Journal of Wildlife Management.
Chapter 4 describes bobcat diet patterns and will be submitted to the Southeastern Naturalist.
Chapter 5 summarizes all findings and conclusions.
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Hall, H. T. and J. D. Newsom. 1976. Summer home ranges and movements of bobcats in
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_____ and _____. 1984. Movements and dispersal of bobcats in eastern Tennessee. Journal of
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central Montana. Canadian Field Naturalist 99:6-12.
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Miller, S. D. and D. W. Speake. 1978. Prey utilization on quail plantations in southern
Alabama. Proceedings of the Annual Conference of the Southeastern Association of Fish
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22
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23
CHAPTER 2
BOBCAT HOME RANGES IN A
LONGLEAF PINE ECOSYSTEM IN SOUTHWESTERN GEORGIA¹
_______________________ ¹Doughty, J., J. C. Cochrane, I. A. Godbois, L.M. Conner, and R. J. Warren. 2004. To be submitted to the American Midland Naturalist.
24
ABSTRACT.─Little is known about bobcat (Lynx rufus) ecology in areas managed for northern
bobwhite (quail; Colinus virginianus). Therefore, we determined seasonal and annual home
range sizes of bobcats in a longleaf pine (Pinus palustris) forest managed for quail in
southwestern Georgia. We monitored 44 radio-collared bobcats during 2001-2004. Average
annual home range size was 11.0 + 1.4 km2 for male bobcats and 6.4 + 1.0 km2 for females.
There was no sex × year interaction (F1,25 = 0.15, P = 0.700). Annual home ranges differed
between sexes (F1,25= 7.54, P = 0.011) but not among years (F1,25 = 2.79, P = 0.107). Male
bobcats had a mean home range size of 8.5 + 1.0 km2 across seasons. The smallest male home
range (2.1 + 3.3 km2) occurred during fall 2001, and the largest home range (15.9 + 2.7 km2)
occurred during winter 2002. Females had a mean home range size of 5.3 + 0.7 km2 across
seasons. The smallest female home range (2.8 + 1.7 km2) occurred during summer 2002 and the
largest home range (8.5 + 1.7 km2) occurred during winter 2003. For seasonal home ranges,
there was a significant sex × season interaction (F10,181 = 1.64, P = 0.100); thus, we examined
seasonal home ranges for the sexes separately. Home range sizes varied seasonally for females
(F10,124 = 3.22, P = 0.001), but not for males (F10,52 = 0.88, P = 0.554). Home ranges of both
sexes were smaller than home ranges previously reported for the southeastern United States.
Land management practices such as prescribed burning and maintenance of food plots
contributed to high quality habitat with ample prey, which probably led to smaller home range
sizes of bobcats on this study area compared to other studies.
25
INTRODUCTION
The bobcat (Lynx rufus) is a solitary carnivore with variable home range sizes influenced
by numerous factors including geographic region, sex, age, season, habitat quality, prey
availability and abundance, and possibly experience (time-in-residence) (Fendley and Buie,
1986; Anderson, 1987; Rucker et al., 1989; Sandell, 1989; Conner et al., 1999). Home ranges of
bobcats in the Southeast vary from 1.1 km2 for females and 2.6 km2 for males (Miller and
Speake, 1979) to 24.5 km2 for females and 64.2 km2 for males (Rucker et al., 1989). Estimates
of composite bobcat home range sizes in southwestern Georgia over 2 years were 2.8 + 0.6 km2
for females and 6.0 + 0.8 km2 for males (Cochrane, 2003).
Male home ranges typically exceed those of females by 2-3 times, and may be as much as
5 times larger (Hall and Newsom, 1976; Buie et al., 1979; Kitchings and Story, 1979; Whitaker
et al., 1987). Male home range size is affected by the size of female home ranges and the
number of mating opportunities, whereas female home ranges appear to be regulated by
diversity, abundance, stability, and distribution of prey populations (Anderson, 1987; Sandell,
1989). Male home ranges may overlap several female and male home ranges, but intrasexual
overlap between females appears rare (Marshall and Jenkins, 1966; Hall and Newsom, 1976;
Buie et al., 1979; Miller and Speake, 1979; McCord and Cordoza, 1982; Whitaker et al., 1987).
However, some studies reported frequent overlap among female home ranges (Zezulak and
Schwab, 1979; Chamberlain and Leopold, 2001; Nielsen and Woolf, 2001).
Differences in habitat quality are the most often used explanation for home range
variability in bobcats (Anderson, 1987). According to the bobcat habitat suitability index model,
the suitability of habitat is determined by the ability of the habitat to support prey populations
(Boyle and Fendley, 1987).
26
Studies have documented an inverse relationship between prey abundance and home range size
(Buie et al., 1979, Knick, 1990). Habitats more suitable for abundant prey densities are more
likely to be included in a bobcat’s home range, and higher quality habitat should result in smaller
home ranges (Buie et al., 1979, Knick, 1990). Conner et al. (2001) suggested that habitat quality
influenced bobcat home range size, but once habitat quality increases to a threshold, home ranges
become influenced by other factors such as density and breeding opportunities.
Home range size also may vary seasonally, though few studies of bobcats in the
Southeast have documented seasonal variation. Males have the largest home range during the
breeding season, and females have the smallest home range during parturition and kitten-rearing
(Anderson, 1987; Knick, 1990; Conner et al., 1992). Seasonal fluctuation in home range sizes
also may relate to seasonal differences in prey availability. Home ranges were smallest during
the summer in Arkansas, probably because prey abundance is greatest during the warmest
months (Rucker et al. 1989). In southwestern Georgia, home ranges were largest for males
during spring and summer (Cochrane, 2003). However, in South Carolina, bobcat home range
size did not fluctuate seasonally (Fendley and Buie, 1986).
Although seasonal home ranges of bobcats in the longleaf pine ecosystem have been
studied, annual home ranges have not been estimated. Our objectives were to determine annual
and seasonal home range sizes of bobcats in a longleaf pine ecosystem in southwestern Georgia.
We hypothesized that male home ranges would be larger than female home ranges, and that
seasonal variation would occur.
27
STUDY AREA
Ichauway is a privately owned 11,735-ha research facility located in Baker County,
Georgia, 16 km south of Newton, Georgia. It is located in the Dougherty Plain physiographic
province in the southeastern Gulf Coastal Plain (Boring 2001). Ichauway is characterized by flat
to gently rolling karst topography, with elevations ranging from 27 to 61 m. It has hot, humid
summers and short, mild, wet winters, with average daily temperatures ranging from 11.1°C
(winter) to 27.2°C (summer). Average annual precipitation is 132 cm per year (Boring 2001).
Longleaf pine woodlands and limesink wetlands are the dominant habitat types at
Ichauway. Other habitats include mixed pine-hardwood areas, food plots, agricultural fields,
slash pine (P. elliottii) flatwoods, riparian hardwood hammocks, oak sandhill barrens, natural
and old-field loblolly pine (P. taeda) stands, grassy and cypress-gum (Taxodium ascendens,
Nyssa biflora) limesink ponds, creek swamps, forested wetlands, riverine areas, shrub-scrub
upland, and human/cultural (i.e., resident quarters) areas (Boring 2001). The understory is
dominated by wiregrass and old-field grasses (e.g., Andropogon spp.), but >1,000 vascular plant
species occur on the site (Goebel et al. 1997, Drew et al. 1998). Approximately 24 km of the
Ichawaynochaway Creek flows through the study area, and the Flint River forms almost 22 km
of Ichauway’s eastern boundary (Boring 2001).
The site is divided into multiple-use and conservation zones interspersed throughout the
land area. Multiple-use zones comprise approximately 60% of Ichauway, and prescribed fire,
supplemental feeding, and maintenance of food plots are the primary management activities in
multiple-use zones. Conservation zones, comprising the remaining 40% of the land area, are
managed for longleaf pine restoration. Bobcats occur in both zones on Ichauway.
28
Much of Ichauway is managed for the longleaf pine-wiregrass ecosystem with prescribed
fire. Burning is performed on a 2-year rotation, usually during winter and early spring, on
approximately 4,000 to 6,000 ha throughout the entire site (Godbois et al. 2004). Prescribed
burning is used to control understory vegetation, reduce hardwoods, manage wildlife habitat,
reduce fuel buildup, promote wiregrass seed production, prepare sites for pine regeneration, and
for experimental research and educational activities (Boring 2001).
Food plots consisting of brown top millet (Brachiaria ramose), winter wheat (Triticum
aestivum), cowpea (Vigna spp.), grain sorghum (Sorghum vulgare), and Egyptian wheat
(Sorghum spp.) comprise 20% of the property (Godbois et al. 2004). Food plots occur less
abundantly in conservation zones than multiple use zones, and are typically planted for white-
tailed deer rather than quail. Supplemental feeding for quail with grain sorghum occurs in
multiple use zones at 2-week intervals between November and May (Godbois et al. 2004).
Fields are disked to improve quail food availability by allowing ragweed (Ambrosia
artemisiifolia) and partridge pea (Chamaecrista fasciculata) seedlings and other plants to grow
(Landers and Mueller 1986, Davis 2001).
Limited predator removal occurs in multiple use zones after the quail-hunting season
(March-May) annually. The primary predators removed are raccoons (Procyon lotor) and
opossums (Didelphis virginiana). Low numbers of coyote (Canis latrans), red fox (Vulpes
vulpes), gray fox (Urocyon cinereoargentus), and striped skunk (Mephitis mephitis) also are
removed each year. Bobcats were harvested occasionally before 1999, but since then have not
been harvested.
29
METHODS
Bobcat capture, handling, and monitoring.─We trapped bobcats with baited #3 Victor Soft
Catch traps (Woodstream Corp., Lititz, PA), and baited #1.75 Oneida Victor coil-spring traps
(Victor Inc., Ltd., Cleveland, OH). Animals were captured from December 2000 until May
2004, though trapping efforts were sporadic between July 2001 and October 2003.
Captured animals were netted and given an intramuscular injection of ketamine hydrochloride
(10 mg/kg body weight) (Seal and Kreeger, 1987). We recorded sex, weight, total body length,
hind foot length, ear length, and tail length, and classified animals as adult or juvenile based on
secondary sex characteristics, length, and weight (Crowe, 1975). Adults were fitted with a 180-g
VHF radio-collar (Advanced Telemetry Systems, Isanti, MN). Each bobcat received a uniquely
numbered ear tattoo. Beginning in November 2003, 3-mm ear punches were taken from every
captured animal for a concurrent genetic study. Bobcats were monitored and released 8 to 24
hours after sedation at the trap site to ensure full recovery. All trapping procedures were
approved by the University of Georgia Institutional Animal Care and Use Committee (IACUC
#A990159).
Using radio telemetry, we began monitoring bobcats 2-7 days after release. We obtained
locations by triangulation, taking ≥2 radio telemetry azimuth locations from known reference
points with a 3-element Yagi antenna (Sirtrack, New Zealand) and hand-held receiver (Wildlife
Materials Inc., Carbondale, IL). To minimize error due to animal movement between readings,
time between consecutive bearings was ≤15 minutes (Cochran, 1980; Kenward, 1987; White and
Garrott, 1990).
30
Each bobcat was located 4-6 times per week, and locations were obtained equally throughout the
diel period, with ≥8 hours between each location to ensure biological independence. We
determined activity (active or inactive) by a change in the pulse rate of the transmitter or signal
intensity when movement was detected (Chamberlain et al., 1998).
Data Analysis.─We used the FORTRAN program EPOLY (L. M. Conner, pers. comm.) to
convert radio telemetry locations into Universal Transverse Mercator (UTM) coordinates. We
calculated 95% adaptive kernel (ADK; Worton, 1989) annual and seasonal home ranges for
bobcats with ≥30 locations per calendar season (annual = 12 consecutive months; fall = 21 Sep-
20 Dec; winter = 21 Dec-20 Mar; spring = 21 Mar-20 Jun; summer = 21 Jun-20 Sep) using
CALHOME (Kie et al., 1996). We also calculated minimum convex polygon (MCP) home
range estimates for comparison with other studies (Mohr, 1947). Annual home ranges were
determined for animals monitored for 4 consecutive seasons.
Statistical analyses were only performed on ADK home range estimates. To determine
whether annual home range differed as a function of sex, year, or a sex × year interaction, we
used an Analysis of Variance (ANOVA) with PROC GLM (SAS Institute, 2003). We used a
repeated measures ANOVA with PROC MIXED to determine whether seasonal home range size
differed as a function of sex, season, or the interaction (SAS Institute, 2003). Animals were
treated as the subject, repeated over seasons. We considered statistical significance at α=0.10.
RESULTS
We radio-tracked 13 - 27 bobcats each season from 21 September 2001-20 June 2004 (44
total animals, 17M and 27F; 29 annual home ranges). Male bobcat (11.0 + 1.4 km2) ADK
annual home ranges were almost 2 times larger (F1,25 = 7.54, P = 0.011) than female (6.4 + 1.0
km2) annual home ranges.
31
Annual home ranges did not differ (F1,25 = 2.79, P = 0.107) among years. There was no sex ×
year interaction (F1,25 = 0.15, P = 0.700). According to MCP estimates, males (8.2 + 1.2 km2)
had a mean annual home range approximately 1.5 times larger than females (5.2 + 1.1 km2).
For seasonal home ranges, there was a significant sex × season interaction (F10,181 = 1.64,
P = 0.100); thus, we examined seasonal home ranges for the sexes separately. Home range sizes
varied seasonally for females (F10,124 = 3.22, P = 0.001), but not for males (F10,51.6 = 0.88, P =
0.554) (Figure 2.1). Male bobcats had a mean home range size of 8.5 + 1.0 km2 across seasons,
and females had a mean home range size of 5.3 + 0.7 km2 across seasons. For males, the
smallest home range (2.1 + 3.3 km2) occurred during fall 2001, and the largest home range (15.9
+ 2.7 km2) occurred during winter 2002. The smallest female home range (2.8 + 1.7 km2)
occurred during summer 2002 and the largest home range (8.5 + 1.7 km2) occurred during winter
2003.
DISCUSSION
Similar to most studies of bobcat home ranges in the southeastern U.S., we found that
male bobcats had larger home ranges than females (Table 2.1). However, home ranges of both
sexes were smaller than home ranges previously reported, probably the result of difference in
habitat quality among study areas (Kitchings and Story, 1979; Buie et al., 1979; Hamilton, 1982;
Shiftlet, 1984; Lancia et al., 1986; Rucker et al., 1989; Conner et al., 1992; Conner et al., 2001).
The ability of a habitat to support prey populations determines the suitability of bobcat habitat
(Boyle and Fendley, 1987). High prey abundance should result in smaller home ranges, because
bobcats in habitats that maintain high prey densities do not have to travel as far to fulfill their
dietary needs (Buie et al., 1979; Knick, 1990).
32
Prescribed fire was a primary land management tool on our study site, which increases
and maintains a dense herbaceous understory and early successional habitat, ultimately providing
abundant resources and habitat for prey populations (Golley et al. 1965; Miller and Speake,
1979). Between 4,000 and 6,000 ha are burned annually on the study area, providing ample
habitat with early-successional herbaceous vegetation. Approximately 20% of the study area is
made up of wildlife food plots and agriculture (Godbois et al., 2004). Planting agricultural crops
and maintaining quail food plots increases edge, which also provides ample resources for prey
(Hall and Newsom, 1976; Miller and Speake, 1978; Cummings and Vessey, 1994). In addition,
approximately 270 metric tons of grain sorghum are spread over 7,020 ha throughout areas on
Ichauway that are managed for quail between November and May each year (Godbois et al.,
2004). In a preliminary analysis of small mammal data collected on our study area, cotton rats
(Sigmodon hispidus) were 5.5 times greater, house mouse (Mus musculus) were 3.5 times
greater, cotton mouse (Peromyscus gossypinus) were 1.5 times greater, and Eastern harvest
mouse (Reithrodontomys humulis) were 2 times greater in supplementally-fed versus unfed areas
(L. M. Conner, Joseph W. Jones Ecological Research Center, unpublished data). Thus, current
land management practices on our study site may have influenced bobcat home range sizes by
concentrating prey populations and concomitantly establishing high quality bobcat habitat.
Seasonal home range sizes differed according to sex. Male home ranges were larger than
females during all seasons except fall 2001. An exceptionally large home range of 1 female
(Bobcat #27, 18.4 km2) may have contributed to the average female home range for fall 2001
being larger than the average male home range size during that season. Although male home
range sizes did not vary seasonally, we observed that males had the largest home ranges during
winter in all 3 years.
33
Similar to other studies, this finding suggests that male bobcats increased their home ranges
during the breeding period, which occurs during the winter months in the southeastern states
(Anderson, 1987; Jackson and Jacobson, 1987; Knick, 1990; Conner et al. 1992). Increasing
their home range during the reproductive season allows males more breeding opportunities by
overlapping more female home ranges (Anderson and Lovallo, 2003).
Female home range sizes varied seasonally. The average home range size during winter
2003 was significantly larger than 9 of the other 10 seasons, which likely explains the seasonal
variation in home range size for female bobcats on our study site. It is possible that during the
colder months prey were more difficult to find, and expansion of the home range was necessary.
However, the home range of several females during that season probably caused the difference.
Bobcat #'s 40, 6, and 18 had home range sizes of 34.7 km2, 17.5 and 14.0 km2, respectively,
which were considerably larger than other females.
Between winter and spring during all 3 years of the study, female home range sizes
declined, which was likely due to females restricting their movements during denning (Bailey,
1974; Knick, 1990). The smallest female home range occurred during summer 2002, which
corresponded to the post-parturition period during that year, in which the female must provide
prey to her kittens (Bailey, 1979; Jackson and Jacobson, 1987; Conner et al., 1992). Home
ranges increased in size between summer and fall seasons, during which kittens become old
enough to travel with their mother (Bailey, 1979).
We concluded that home ranges of bobcats in southwestern Georgia were smaller than
most home ranges previously reported for the Southeast. Land management practices such as
prescribed burning, supplemental feeding, and maintenance of food plots likely contributed to
high quality habitat with ample prey.
34
High quality habitat containing abundant prey resources probably contributed to smaller home
range sizes of bobcats in the longleaf pine ecosystem compared to most other studies. Future
research should document prey population densities and bobcat locations in burned versus non-
burned areas and in food plots versus non-food plots, which might provide stronger evidence of
the role land management practices play in bobcat ecology in the longleaf pine forest.
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Crowe, D. M. 1975. Aspects of aging, growth, and reproduction of bobcats from Wyoming.
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Hall, H. T. and J. D. Newsom. 1976. Summer home ranges and movements of bobcats in
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Idaho. Wildl. Mono., 108. 42 pp.
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management. Caesar Kleberg Wildlife Research Institute, Kingsville, Texas, USA.
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Timbers Research Station and Quail Unlimited, Tallahassee, Florida, USA.
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Marshall, A. D. and J. H. Jenkins. 1966. Movements and home ranges of bobcats as determined
by radio-tracking in the upper coastal plain of South Carolina. Proc. Annu. Conf.
Southeast. Assoc. of Game and Fish Comm., 20:206-214.
McCord, C. M. and J. E. Cordoza. 1982. Bobcat and lynx. Pages 728-766 In: J. A. Chapman
and G. A. Feldhamer, (eds.). Wild mammals of North America. Johns Hopkins
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Miller, S. D. and D. W. Speake. 1978. Prey utilization on quail plantations in southern
Alabama. Proc. Annu. Conf. Southeast. Assoc. of Game and Fish Comm., 32:100-111.
_____ and _____. 1979. Progress report: demography and home range of the bobcat in south
Alabama. Pages 123-124 In: L. G. Blum and P.C. Escherich, (eds.). Proc. Bobcat Res.
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Illinois. Am. Midl. Nat., 146:43-52.
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Rucker, R. A., M. L. Kennedy, G. A. Heidt, and M. J. Harvey. 1989. Population density,
movements, and habitat use of bobcats in Arkansas. Southwest. Nat., 34:101-108.
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182 In: J. L. Gittleman, (ed.). Carnivore behavior, ecology and evolution. Cornell
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M. Novak, J. A. Baker, M. E. Obbard, and B. Malloch, (eds.). Wild furbearer
management and conservation in North America. Ministry of Natural Resources,
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hardwoods. Thesis, Louisiana State University, Baton Rouge, Louisiana, USA.
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Kentucky bobcats. Proc. Annu. Conf. Southeast. Assoc. of Fish and Wildl. Agencies,
41:417-423.
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Inc., San Diego, California. 383 pp.
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Ecol., 70:164-168.
Zezulak, D. S. and R. G. Schwab. 1979. A comparison of density, home-range, and habitat
utilization of bobcat populations at Lava Beds and Joshua Tree National Monuments,
California. Pages 74-79 In: L. G. Blum and P.C. Escherich, (eds.). Proc. Bobcat Res.
Conf., National Wildlife Federation Scientific and Technical Series 6.
40
Figure 2.1. Seasonal home range sizes for male and female bobcats (F01=Fall 2001;
W02=Winter 2002; S02=Spring 2002; Su02=Summer 2002; F02=Fall 2002; W03=Winter 2003;
S03=Spring 2003; Su03=Summer 2003; F03=Fall 2003; W04=Winter 2004; S04=Spring 2004)
on Ichauway, Baker County, Georgia, 2001-2004.
41
seasons
F01 W02 S02 Su02 F02 W03 S03 Su03 F03 W04 S04
hom
e ra
nge
size
(km
2 )
-2
0
2
4
6
8
10
12
14
16
18
20
22
Males
Females
42
Table 2.1. Studies documenting bobcat home range sizes (km²) in the southeastern United States (MMA=Modified Minimum Area; MCP=Minimum Convex Polygon; ADK=Adaptive Kernel). ______________________________________________________________________________ Reference State Sample Home range Home range size M F model ______________________________________________________________________________
Hall and Newsom, 1976a LA 6 4.9 1.0 MMA
Kitchings and Story, 1979 TN 5 42.9 11.5 MCP
Miller and Speake, 1979 AL 20 2.6 1.1 MCP
Buie et al., 1979b SC 6 20.8 10.3 MCP
Hamilton, 1982 MO 30 60.4 16.1 MCP
Shiftlet, 1984 MS 7 10.1 5.9 MCP
Fendley and Buie, 1986 SC 7 3.2 1.6 MCP
Lancia et al., 1986d NC 8 37.7 22.1 MCP
Rucker et al., 1989 AR 6 64.2 24.5 MCP
Conner et al., 1992 MS 15 36.5 20.6 MCP
Griffin, 2001 SC 8 10.5-16.7 3.5-10.5 ADK
Conner et al., 2001 MS 42 20.2 12.3 MCP
This study GA 29 8.2 5.2 MCP This study GA 29 11.0 6.4 ADK ______________________________________________________________________________ a Used only summer data. b Used only fall and winter data.
43
CHAPTER 3
FACTORS AFFECTING BOBCAT HABITAT USE
IN A LONGLEAF PINE ECOSYSTEM IN SOUTHWESTERN GEORGIA¹
_______________________ ¹Doughty, J., J. C. Cochrane, I. A. Godbois, L.M. Conner, and R. J. Warren. 2004. To be submitted to the Journal of Wildlife Management.
44
Abstract: Little is known about bobcat (Lynx rufus) ecology in areas managed for northern
bobwhite (quail; Colinus virginianus). We investigated bobcat habitat use in a longleaf pine
(Pinus palustris) forest managed for quail in southwestern Georgia. We monitored 43 radio-
collared bobcats from 2001 – 2004 to determine habitat use at 2 spatial scales: second order
(habitat selection of home range within the study site) and third order (habitat selection within an
individual’s home range). We also investigated whether activity status (active or inactive) of
individuals or time-of-day (day, night, or crepuscular) affected habitat use. At the second order
of selection, there was no sex × season interaction (Λ = 0.804, P = 1.000), and season had no
effect (Λ = 0.708, P = 0.783). Male and female bobcats selected habitat differently (Λ = 0.919,
P = 0.033). Female bobcats were closer to all habitat types than expected, suggesting a
preference for edges. Females preferred agriculture over all other habitat types. Male bobcats
were closer to agriculture, hardwood, pine regeneration, pine, mixed hardwood, and urban/barren
habitat types than expected, and they preferred agriculture over all other habitat types. At the
third order of selection, there was no sex × season interaction (Λ = 0.786, P = 0.998). Bobcat
habitat selection did not differ by sex (Λ = 0.947, P = 0.210) or season (Λ = 0.654, P = 0.306).
When data for sex and season were pooled, overall habitat selection occurred (Λ = 0.596,
P = 0.012). Urban/barren was most preferred, followed by wetland, hardwood, agriculture,
shrub/scrub, pine regeneration, pine, and mixed pine-hardwood. Bobcats did not select habitat
differently according to activity status (Λ = 0.990, P = 0.981) or time-of-day (Λ = 0.972,
P = 0.647). We suggest that bobcats on our study site prefer agricultural areas and other habitats
that provide a dense herbaceous layer because they produce abundant prey. Prescribed fire,
interspersed food plots, and other quail management practices create habitats preferred by
bobcats.
45
Key Words: activity status, bobcat, Georgia, habitat use, Johnson's second order selection,
Johnson's third order selection, longleaf pine, Lynx rufus, time-of-day
______________________________________________________________________________
INTRODUCTION
Habitat use patterns vary throughout the geographic range of the bobcat (Lynx rufus), but
prey abundance is the major determinant in habitat selection (Pollack 1951, Anderson 1987,
Rucker et al. 1989). Other factors that influence habitat use include resting site availability,
denning site availability, protection from environmental extremes, dense cover for hunting and
escape, and freedom from disturbance (Pollack 1951, Young 1958, Bailey 1974, Kitchings and
Story 1984, Anderson 1987, Boyle and Fendley 1987). Activity status and time-of-day are
potential influences on bobcat habitat use, but such influences have not been studied.
Shrub interspersion is necessary to provide cover for prey species (Schnell 1968).
Bobcat prey in the Southeast, especially the cotton rat (Sigmodon hispidus) and the eastern
cottontail (Sylvilagus floridanus), are most abundant in dense areas of early to mid-successional
grass/forb-shrub vegetation (Boyle and Fendley 1987). Cotton rats and other rodents also occur
in high densities in broomsedge (Andropogon spp.)-vine habitat, characterized by herbaceous
species interspersed with shrubs and shrubby vines such as blackberry (Rubus spp.), Japanese
honeysuckle (Lonicera japonica), and trumpet vine (Bignonia radicans) (Golley et al. 1965), and
they are commonly found near agriculture and food plots (Cummings and Vessey 1994). In the
Southeast, habitats selected by bobcats include pine plantations and agricultural areas (Conner et
al. 1992, Cochrane 2003), and bottomland hardwoods (Heller and Fendley 1986, Cochrane
2003).
46
Bobcats also prefer hardwoods associated with drainages in forested upland (Zwank et al. 1985),
and mid-successional stages with dense growth of saplings, vines and briars in bottomland
hardwoods (Hall and Newsom 1976). These habitats have more abundant prey than mature pine
forests and other available habitats.
There is a paucity of information about bobcat habitat use in a longleaf pine (Pinus
palustris)-wiregrass (Aristida stricta) ecosystem. Therefore, the objectives of this study were to
determine bobcat habitat use at Johnson's second and third orders of selection (Johnson 1980),
and to determine whether activity status and time-of-day affect habitat use. We hypothesized
that bobcats would select early successional habitat types and edges, that active animals would
be located more than expected in early successional habitat types, and that early successional
habitats would be used more than expected during night and crepuscular periods.
STUDY AREA
Ichauway is a privately owned 11,735-ha research facility located in Baker County,
Georgia, 16 km south of Newton, Georgia. It is located in the Dougherty Plain physiographic
province in the southeastern Gulf Coastal Plain (Boring 2001). Ichauway is characterized by flat
to gently rolling karst topography, with elevations ranging from 27 to 61 m. It has hot, humid
summers and short, mild, wet winters, with average daily temperatures ranging from 11.1°C
(winter) to 27.2°C (summer). Average annual precipitation is 132 cm per year (Boring 2001).
Longleaf pine woodlands and limesink wetlands are the dominant habitat types at
Ichauway. Other habitats include mixed pine-hardwood areas, food plots, agricultural fields,
slash pine (P. elliottii) flatwoods, riparian hardwood hammocks, and oak sandhill barrens.
47
Natural and old-field loblolly pine (P. taeda) stands, grassy and cypress-gum (Taxodium
ascendens, Nyssa biflora) limesink ponds, creek swamps, forested wetlands, riverine areas,
shrub-scrub upland, and human/cultural (i.e., resident quarters) areas are also found at Ichauway
(Boring 2001). The understory is dominated by wiregrass and old-field grasses (e.g.,
Andropogon spp.), but >1,000 vascular plant species occur on the site (Goebel et al. 1997, Drew
et al. 1998). Approximately 24 km of the Ichawaynochaway Creek flows through the study area,
and the Flint River forms almost 22 km of Ichauway’s eastern boundary (Boring 2001).
The site is divided into multiple-use and conservation zones interspersed throughout the
land area. Multiple-use zones comprise approximately 60% of Ichauway, and prescribed fire,
supplemental feeding, and maintenance of food plots are the primary management activities in
multiple-use zones. Conservation zones, comprising the remaining 40% of the land area, are
managed for longleaf pine restoration. Bobcats occur in both zones on Ichauway.
Much of Ichauway is managed for the longleaf pine-wiregrass ecosystem with prescribed
fire. Burning is performed on a 2-year rotation, usually during winter and early spring, on
approximately 4,000 to 6,000 ha throughout the entire site (Godbois et al. 2004). Prescribed
burning is used to control understory vegetation, reduce hardwoods, manage wildlife habitat,
reduce fuel buildup, promote wiregrass seed production, prepare sites for pine regeneration, and
for experimental research and educational activities (Boring 2001).
Food plots consisting of brown top millet (Brachiaria ramose), winter wheat (Triticum
aestivum), cowpea (Vigna spp.), grain sorghum (Sorghum vulgare), and Egyptian wheat
(Sorghum spp.) comprise 20% of the property (Godbois et al. 2004). Food plots occur less
abundantly in conservation zones than multiple use zones, and are typically planted for white-
tailed deer rather than quail.
48
Supplemental feeding for quail with grain sorghum occurs in multiple use zones at 2-week
intervals between November and May (Godbois et al. 2004). Fields are disked to improve quail
food availability by allowing ragweed (Ambrosia artemisiifolia) and partridge pea
(Chamaecrista fasciculata) seedlings and other plants to grow (Landers and Mueller 1986, Davis
2001).
Limited predator removal occurs in multiple use zones after the quail-hunting season
(March-May) annually. The primary predators removed are raccoons (Procyon lotor) and
opossums (Didelphis virginiana). Low numbers of coyote (Canis latrans), red fox (Vulpes
vulpes), gray fox (Urocyon cinereoargentus), and striped skunk (Mephitis mephitis) also are
removed each year. Bobcats were harvested occasionally before 1999, but since then have not
been harvested.
METHODS
Bobcat capture, handling, and monitoring
We trapped bobcats with baited #3 Victor Soft Catch traps (Woodstream Corp., Lititz,
PA), and baited #1.75 Oneida Victor coil-spring traps (Victor Inc., Ltd., Cleveland, OH).
Animals were captured from December 2000 until May 2004, though trapping efforts were
sporadic between July 2001 and October 2003. Captured animals were netted and given an
intramuscular injection of ketamine hydrochloride (10 mg/kg body weight) (Seal and Kreeger
1987). We recorded sex, weight, total body length, hind foot length, ear length, and tail length,
and classified animals as adult or juvenile based on secondary sex characteristics, length, and
weight (Crowe 1975).
We fitted adults with a 180-g VHF radio-collar (Advanced Telemetry Systems, Isanti,
MN). Each bobcat received a uniquely numbered ear tattoo.
49
Beginning in November 2003, 3-mm ear punches were taken from every captured animal for a
concurrent DNA study. We monitored and released bobcats 8 to 24 hours after sedation at the
trap site to ensure full recovery from sedation. All trapping procedures were approved by the
University of Georgia Institutional Animal Care and Use Committee (IACUC #A990159).
Using radio telemetry, we began monitoring bobcats 2-7 days after release. We obtained
locations by triangulation, taking ≥2 radio telemetry azimuth locations from known reference
points with a 3-element Yagi antenna (Sirtrack, New Zealand) and hand-held receiver (Wildlife
Materials Inc., Carbondale, IL). Each bobcat was located 4-6 times per week, and locations were
obtained equally throughout the diel period, with ≥8 hours between each location to ensure
biological independence. To minimize error due to animal movement between readings, time
between consecutive bearings was ≤15 minutes (Cochran 1980, Kenward 1987, White and
Garrot 1990). We determined activity (active or inactive) by a change in the pulse rate of the
transmitter or signal intensity when movement was detected (Chamberlain et al. 1998).
Data Analysis
We used the FORTRAN program EPOLY (L. M. Conner, Joseph W. Jones Ecological
Research Center, unpublished data) to convert radio telemetry locations into Universal
Transverse Mercator (UTM) coordinates. We calculated 95% minimum convex polygon (MCP;
Mohr 1947) annual and seasonal home ranges for bobcats with ≥30 locations per calendar season
(e.g., fall = Sep-Dec; winter = Dec-Mar; spring = Mar-Jun; summer = Jun-Sep) using
CALHOME (Kie et al. 1996). We performed all habitat analyses using ARC/INFO and
Geographic Information System (GIS) software (ESRI 2004).
50
Habitat was classified into 8 types [agriculture/food plot (20.2%), shrub/scrub (1.6%), hardwood
(10.8%), pine regeneration (4.4%), pine (31.8%), mixed pine-hardwood (24.5%), wetland
(5.0%), and urban/barren (1.5%)] and digitized from aerial photo-interpretation ARC/INFO into
a GIS. Bobcat locations and home ranges were intersected onto habitat maps using ARC/INFO.
We determined habitat use at 2 spatial scales: Johnson's second order (habitat selection of
home range within the study site) and Johnson's third order (habitat selection within an
individual’s home range) (Johnson 1980). We used a Euclidean distance technique to test for
habitat selection by comparing the mean distance between animal locations and habitat types to
corresponding expected distances (Conner and Plowman 2001, Conner et al. 2003).
Random locations for the study area and for each home range were generated, and we
calculated the mean distance (m) from random locations in the study area to each habitat type
and random locations within each home range to each habitat type using the NEAR command in
ARC/INFO (ESRI 2004). We also calculated mean distances from each bobcat location to each
habitat type in the home range. For second order selection, we created 8 distance ratios for each
bobcat (1 for each habitat type): the average distances from random locations within the home
range to each habitat type divided by the average distances from random locations in the study
area to each habitat type. For third order selection, we created 8 additional distance ratios—the
average distances from bobcat locations within the home range (i.e., used distances) to each
habitat type divided by the average distances from random locations within the home range (i.e.,
random distances) to each habitat type.
51
We assessed differences in habitat use as a function of sex, season, and their interaction
using a 2-factor multivariate analysis of variance (MANOVA). We expected the ratio of used
distances to random distances to equal 1.0 if habitat use was random (i.e., no selection) (Conner
and Plowman 2001, Conner et al. 2003). If the ratio was <1, the habitat type was preferred; if
the ratio was >1, the habitat type was avoided. We used univariate t-tests on each habitat type to
determine disproportional habitat use if the distance ratio did not equal 1. Ranking matrices
were created using univariate t-tests (i.e., pairwise mean comparisons) to rank habitat types.
All statistical analyses were performed with SAS software (SAS Institute, 2003). We considered
statistical significance at α=0.10.
We also investigated whether activity status and time-of-day affected habitat selection
seasonally. We defined an active animal as one that was observed moving (by a change in the
transmitter motion switch or signal intensity) during one or both radio-telemetry bearings for
each location. We defined daytime as the time from 2 hours after sunrise to 2 hours before
sunset on the median day of each calendar season, and nighttime as the time from 2 hours after
sunset to 2 hours before sunrise on the median day of each calendar season, taking into account
Daylight Saving Time during the appropriate seasons. We defined crepuscular periods as the
time period 2 hours before and 2 hours after sunrise and sunset. Seasons were pooled across
years (e.g., Fall = fall 2001, 2002 and 2003). We analyzed differences in habitat use according
to activity, sex and season using the Euclidean distance technique and a 3-factor MANOVA.
Similarly, we used a 3-factor MANOVA to detect differences in habitat use according to time-
of-day, sex, and season.
52
RESULTS
We radio-tracked 13 - 27 bobcats each season from 21 September 2001-20 June 2004 (43
total animals, 16M and 27F). At the second order of selection, there was no sex × season
interaction (Λ = 0.804, P = 1.000), and season had no effect (Λ = 0.708, P = 0.783). Therefore,
seasonal data were combined to analyze the sexes separately. Male and female bobcats selected
habitat differently (Λ = 0.919, P = 0.033). Female bobcats were closer to all habitat types than
expected (Table 3.1), suggesting a preference for edges. Females preferred agriculture over all
other habitat types, followed by mixed pine-hardwood, pine regeneration, hardwood, wetland,
shrub/scrub, urban/barren, and pine (Table 3.2). Male bobcats were closer to agriculture,
hardwood, pine regeneration, pine, mixed pine-hardwood, and urban/barren habitat types than
expected (Table 3.3). They preferred agriculture over all other habitat types, followed by mixed
pine-hardwood, pine, hardwood, urban/barren, wetland, pine regeneration, and shrub/scrub
(Table 3.4). Males significantly preferred agriculture over shrub/scrub, pine regeneration,
wetland, and urban/barren.
At the third order of selection, there was no sex × season interaction (Λ = 0.786, P =
0.998). Bobcats habitat selection did not differ by sex (Λ = 0.947, P = 0.210) or season
(Λ = 0.654, P = 0.306). When data for sex and season were pooled, overall habitat selection
occurred (Λ = 0.596, P = 0.012). Bobcats were farther than expected from pine regeneration,
pine, and mixed pine-hardwood, but were closer than expected to wetland and urban/barren
habitat (Table 3.5). Urban/barren was most preferred, followed by wetland, hardwood,
agriculture, shrub/scrub, pine regeneration, pine, and mixed pine-hardwood (Table 3.6).
Contrary to our hypotheses, bobcats did not select habitat differently according to activity status
(Λ = 0.990, P = 0.981) or time-of-day (Λ = 0.972, P = 0.647).
53
DISCUSSION
In the longleaf pine ecosystem of Ichauway, bobcats selected habitats to include in their
home range (Johnson's second order of selection), but did not select habitats within the home
range (Johnson's third order of selection). At Johnson's second order, female bobcats were closer
to all habitat types (agriculture, shrub/scrub, hardwood, pine regeneration, pine, mixed pine-
hardwood, wetland and urban/barren) than expected, and males were closer then expected to all
habitat types except shrub/scrub and wetland. According to Conner et al. (2003), animals prefer
edge when closer to all habitat types than expected. Thus, bobcats appeared to prefer edge when
establishing home ranges. Edge provides travel routes and access to hunting areas such as
agriculture fields, and it is typically where an abundance of prey is found (Landers and Mueller
1986, Cummings and Vessey 1994).
Similar to other studies in the Southeast, our bobcats preferred agriculture (Cochrane
2003, Conner et al. 1992), mixed pine-hardwood (Cochrane 2003), pine (Conner et al. 1992), and
hardwood habitats (Hall and Newsom 1976, Lancia et al. 1986). Bobcats likely selected early
and mid-successional habitats due to prey abundance and availability. Cotton rats and eastern
cottontails, two primary bobcat prey species in the Southeast, are typically most abundant in
dense areas of early to mid-successional grass/forb-shrub vegetation (Boyle and Fendley 1987).
Agricultural areas (e.g. food plots and edges) also attract rodent and lagomorph species
(Cummings and Vessey 1994). Hardwood and mixed pine-hardwood habitats contain a dense
herbaceous understory and shrub interspersion necessary to provide essential cover for prey
species, and such habitats also provide bobcats with cover (Golley et al. 1965, Schnell 1968).
54
On our study area, the mixed pine hardwood and hardwood habitat types are commonly
associated with wet areas near the creek and river. Thus, in addition to providing suitable
resources for bobcats and their prey, these habitats also provided cool, shady areas for refuge
(Godbois 2003).
We observed sex-related differences in habitat use at Johnson's second order. Females
preferred agriculture over all other habitat types, whereas males preferred agriculture over
shrub/scrub, pine regeneration, wetland, and urban/barren. Females preferred pine regeneration
more than males, whereas males preferred pine more than females. Females typically use higher
quality habitat than males because they require more prey within smaller home ranges, especially
with increased energy demands during kitten-rearing (Rolley and Warde 1985). Den site
availability also influences habitat use in females, and potential den sites may be found in
hardwood and mixed pine-hardwood habitat types (Bailey 1974).
At Johnson's third order, bobcat habitat selection did not differ by sex, season, or their
interaction. Bobcats used agriculture, shrub/scrub, hardwood, and wetland habitat types as
expected. They were farther than expected from pine regeneration, pine, and mixed pine-
hardwood. However, bobcats were closer than expected to urban/barren habitat, probably
because 1 female and 1 male (Bobcat #10 and #34, respectively) maintained home ranges in the
vicinity of the laboratory, research, and residential buildings on Ichauway, where most of the
urban/barren habitat was located. Habitat selection within the home range was likely not as
critical because high-quality habitat was selected when establishing the home range (Cochrane
2003).
55
Although bobcats are considered nocturnal, evidence suggests that they are most active
during the hours around sunrise and sunset, which corresponds with activity peaks of rodents and
lagomorphs, the primary prey species (Marshall and Jenkins 1966, Hall and Newsom 1976,
Kitchings and Story 1978, Buie et al. 1979, Anderson 1987, Chamberlain et al. 1998). We
expected active animals to select agriculture and other early-to-mid-successional habitat types
more than inactive animals. We also expected bobcats to prefer early-to-mid-successional
habitats during the nighttime and crepuscular periods. Contrary to our hypotheses, bobcats did
not select habitat differently according to activity status or time-of-day. Because bobcats
selected early-to-mid-successional habitat types to include in their home ranges and such habitats
may provide dense herbaceous cover, resting animals (i.e., inactive) likely did not have to find
cover in other habitat types. If preferred habitats provided ample prey and resting sites, then
bobcats probably did not have to move to other habitats during periods of rest or at different
times throughout the diel period.
MANAGEMENT IMPLICATIONS
Our findings suggest that bobcat habitat selection is probably determined by prey
availability. Rodents are commonly found in agricultural areas containing food plots, and
bobcats preferred agricultural habitats over all other habitat types. Habitat should be managed to
provide a dense herbaceous layer for prey and bobcats. Prescribed fire is the primary
management tool in the longleaf pine ecosystem that maintains such vegetation. In addition,
managing for a mosaic of diverse habitat types increases the amount of edge available, which is
an important component of bobcat habitat. Although we did not find activity status or time-of-
day as factors influencing habitat selection by bobcats, consideration of such factors may be
important to other species that are strictly nocturnal, diurnal, or crepuscular.
56
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movements, and habitat use of bobcats in Arkansas. Southwestern Naturalist 34:101-108.
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management and conservation in North America. Ministry of Natural Resources,
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61
Table 3.1. Mean habitat type distance ratios for second-order selection using seasonal home ranges for female bobcats at Ichauway, Baker County, Georgia, 2001-2004. _________________________________________________________________________ Habitat type Meana t Pb
_________________________________________________________________________ Agriculture -0.3473 -7.08 <0.0001
Shrub/Scrub -0.0700 -0.80 0.4301
Hardwood -0.1104 -1.82 0.0808
Pine regeneration -0.1301 -1.39 0.1753
Pine -0.0434 -0.44 0.6634
Mixed pine-hardwood -0.1616 -2.48 0.0198
Wetland -0.0091 -0.11 0.9140
Urban/Barren -0.0314 -0.42 0.6777 _________________________________________________________________________
aAverage distance from random locations within home ranges divided by average distance from random locations throughout study area. Mean ratios <1 indicate habitat preference; >1 habitat avoidance. bProbability that the mean ratio = 1.0.
Agriculture +++a +++ +++ +++ +++ +++ +++
62
Table 3.2. Habitat rankings based on pair-wise comparisons between habitat type distance ratios for second-order habitat selection, using seasonal home ranges of female bobcats monitored on Ichauway, Baker County, Georgia, 2001-2004. ____________________________________________________________________________________________________________
Agriculture Mixed pine- Pine Hardwood Wetland Shrub/Scrub Urban/Barren Pine hardwood regeneration ____________________________________________________________________________________________________________
Mixed ---a +b +++ +++ +++ +++ +++ pine-hardwood Pine --- --- + + + +++ +++ regeneration
Hardwood --- --- --- + + +++ +++
Wetland --- --- - - + +++ +++
Shrub/Scrub --- --- - - - + +
Urban/Barren --- --- --- --- --- - +
Pine --- --- --- --- --- - - ____________________________________________________________________________________________________________ a Three plus signs indicate row habitat significantly preferred over column and 3 minus signs indicate column habitat significantly preferred over row (t test, P>0.10). bA plus sign indicates that the row habitat type was closer to preference.
63
Table 3.3. Habitat type distance ratios for second-order selection using seasonal home ranges for male bobcats at Ichauway, Baker County, Georgia, 2001-2004. _________________________________________________________________________ Habitat type Meana t Pb
_________________________________________________________________________ Agriculture -0.2813 -3.00 0.0090
Shrub/Scrub 0.0257 0.21 0.8358
Hardwood -0.1601 -2.18 0.0460
Pine regeneration -0.1527 -1.13 0.2767
Pine -0.1374 -1.31 0.2100
Mixed pine-hardwood -0.0800 -1.32 0.2071
Wetland 0.0320 0.23 0.8250
Urban/Barren -0.0152 -0.19 0.8521 _________________________________________________________________________
aAverage distance from random locations within home ranges divided by average distance from random locations throughout study area. Mean ratios <1 indicate habitat preference; >1 habitat avoidance. bProbability that the mean ratio = 1.0.
Agriculture + + +++a +++ +++ +++ +++
64
Table 3.4. Habitat rankings based on pair-wise comparisons between habitat type distance ratios for second-order habitat selection, using seasonal home ranges of male bobcats monitored on Ichauway, Baker County, Georgia, 2001-2004. ____________________________________________________________________________________________________________
Agriculture Mixed pine- Pine Hardwood Urban/Barren Wetland Pine Shrub/Scrub hardwood regeneration ____________________________________________________________________________________________________________
Mixed - +b + +++ +++ +++ +++ pine-hardwood Pine ---a - + + + + +++ Hardwood --- - - + + +++ +++ Urban/Barren --- --- - - + + +++ Wetland --- --- - - - + +++ Pine --- --- - --- - - + regeneration Shrub/Scrub --- --- --- --- --- --- - ____________________________________________________________________________________________________________ a Three plus signs indicate row habitat significantly preferred over column and 3 minus signs indicate column habitat significantly preferred over row (t test, P>0.10). bA plus sign indicates that the row habitat type was closer to preference.
65
Table 3.5. Habitat type distance ratios for third-order selection using seasonal home ranges for male and female bobcats combined at Ichauway, Baker County, Georgia, 2001-2004. _________________________________________________________________________ Habitat type Meana t Pb
_________________________________________________________________________ Agriculture 0.0366 0.75 0.4561
Shrub/Scrub 0.0443 1.41 0.1673
Hardwood 0.0273 0.57 0.5748
Pine regeneration 0.1118 2.98 0.0048
Pine 0.1327 1.77 0.0844
Mixed pine-hardwood 0.2538 2.44 0.0190
Wetland -0.0004 -0.02 0.9875
Urban/Barren -0.0431 -2.01 0.0511 _________________________________________________________________________
aAverage distance from random locations within home ranges divided by average distance from random locations throughout study area. Mean ratios <1 indicate habitat preference; >1 habitat avoidance. bProbability that the mean ratio = 1.0.
Urban/Barren +b +++a + +++ +++ +++ +++
Shrub/Scrub --- - - - + + +++
Wetland - + + + +++ +++ +++
Hardwood ---a - + + +++ + +++
Agriculture - - - + + + +++
66
Table 3.6. Habitat rankings based on pair-wise comparisons between habitat type distance ratios for third-order habitat selection, using seasonal home ranges of all bobcats monitored on Ichauway, Baker County, Georgia, 2001-2004. ____________________________________________________________________________________________________________
Urban/Barren Wetland Hardwood Agriculture Shrub/Scrub Pine Pine Mixed pine- regeneration hardwood____________________________________________________________________________________________________________
Pine --- --- --- - - + + regeneration Pine --- --- - - - - + Mixed --- --- --- --- --- - - pine-hardwood ___________________________________________________________________________________________________________ a Three plus signs indicate row habitat significantly preferred over column and 3 minus signs indicate column habitat significantly preferred over row (t test, P>0.10). bA plus sign indicates that the row habitat type was closer to preference.
67
CHAPTER 4
BOBCAT DIETS IN A LONGLEAF PINE ECOSYSTEM
IN SOUTHWESTERN GEORGIA¹
_______________________ ¹Doughty, J., J. C. Cochrane, I. A. Godbois, L.M. Conner, and R. J. Warren. 2004. To be submitted to the Southeastern Naturalist.
68
ABSTRACT: Because northern bobwhite (quail; Colinus virginianus) hunting is an important
cultural and economic tradition in the Southeast and because quail management is an important
part of the longleaf pine (Pinus palustris)-wiregrass (Aristida stricta) ecosystem, it is important
to understand the impacts of bobcats (Lynx rufus) on quail. Here, we quantify seasonal and
annual diet of bobcats in a longleaf pine forest managed for quail. We collected 413 scats from
21 June 2001 to 20 June 2004. When possible, we identified prey items to species, but we
categorized scat components into 5 major prey groups (rodent, bird, rabbit, deer, and other) for
analysis. Bobcat diets varied among years (χ28 = 47.105, P < 0.001); therefore, we analyzed
seasonal variation for each year separately. Rodent comprised 75.1% of all scats, followed by:
other (21.8%), rabbit (Sylvilagus spp.; 20.6%), bird (13.1%) and deer (Odocoileus virginianus;
7.8%). Cotton rat (Sigmodon hispidus) comprised most (i.e., >60%) of the rodent category
during all years. Quail comprised 1.9% of all samples analyzed. Diet varied among seasons
during year 1 (χ212 = 19.934, P = 0.068) and year 2 (χ2
12 = 23.674, P = 0.023), but not during year
3 (χ212 = 17.352, P = 0.137). Bobcats were not a major predator of quail, but they were a major
predator of cotton rats and other rodents, which may compete with quail for resources. Further
investigation of the relationships between bobcats, rodents, and quail is necessary to better
understand whether bobcats may benefit quail by reducing populations of their competitors.
INTRODUCTION
Bobcats (Lynx rufus) primarily consume rabbits and hares, particularly cottontail rabbits
(Sylvilagus spp.), throughout their range (Anderson 1987). Rodents comprise the remaining bulk
of the diet, though species vary by habitat and locality. Some ground-dwelling avian (i.e., game
and nongame) and reptilian (i.e., snakes) species also are consumed.
69
In the Southeast, cotton rats (Sigmodon hispidus) and eastern cottontails (Sylvilagus floridanus)
compose most of the diet of bobcats during all seasons, and cotton rats replace eastern cottontails
as the primary prey source when they are more abundant (Beasom and Moore 1977, Miller and
Speake 1978, Boyle and Fendley 1987, Cochrane 2003).
Bobcats may exhibit a functional response to changing prey availability (Baker et al.
2001). White-tailed deer (Odocoileus virginianus) become an important food source in some
southern regions, especially during fall-winter when carrion from the hunting season is available,
and in late spring-summer, when fawns are available (Buttrey 1979, Story et al. 1982). Deer also
become an important food source during periods of low density of preferred prey (Beasom and
Moore 1977). In mountainous and highland regions of the South, squirrels (Sciurus spp.), pine
voles (Microtus pinetorum), and some bird species become important food sources (Buttrey
1979, Kitchings and Story 1979). Bobcats also ingest grass, either accidentally or intentionally
as a purgative (Miller and Speake 1978, Buttrey 1979).
Predators generally prey on species within certain size limits to optimize ease in capture
and energy returns (Rosenzweig 1966, McCord and Cordoza 1982). Bobcats concentrate kills on
prey from 150-5,500 g, and consume larger prey less frequently (Rosenzweig 1966, McCord and
Cordoza 1982, Story et al. 1982, Boyle and Fendley 1987, Anderson and Lovallo 2003). Sex
and age-related differences in food habits occur based on individual body size of bobcats. In
Arkansas, females consume more rats and mice than males (Fritts and Sealander 1978), and in
New Hampshire, males consume more white-tailed deer and fewer cottontails than females and
juveniles (Litvaitis et al. 1984). Such differences in food habits may decrease intraspecific
competition within bobcat populations (Rosenzweig 1966, Fritts and Sealander 1978).
70
Although bobcats historically have been considered a major predator of northern
bobwhite (quail; Colinus virginianus), few studies have specifically analyzed bobcat food habits
in areas managed for quail. On two quail plantations in southern Alabama, quail were not an
important part of bobcat diets despite a high density of quail (Miller and Speake 1978). On our
study area in southwestern Georgia, quail remains were found in 1.9% of all bobcat scats
collected over a 2-year period (Cochrane 2003). However, a different study found that quail
remains constituted between 0% and 12.5% of bobcat scats on one of two plantations
neighboring our study site (Schoch 2003).
Because quail hunting is an important cultural and economic tradition in the Southeast,
and quail management is an important part of the longleaf pine (Pinus palustris)-wiregrass
(Aristida stricta) ecosystem, it is important to understand the impacts of bobcats on quail (Burger
et al. 1999, Boring 2001). Our objective was to compare annual and seasonal diets of bobcats in
a longleaf pine forest managed for northern bobwhite. We predicted that diets would vary
among years, and that they would vary seasonally as a result of seasonal availability of prey
species.
STUDY AREA
Ichauway is a privately owned 11,735-ha research facility located in Baker County,
Georgia, 16 km south of Newton, Georgia. It is located in the Dougherty Plain physiographic
province in the southeastern Gulf Coastal Plain (Boring 2001). Ichauway is characterized by flat
to gently rolling karst topography, with elevations ranging from 27 to 61 m. It has hot, humid
summers and short, mild, wet winters, with average daily temperatures ranging from 11.1°C
(winter) to 27.2°C (summer). Average annual precipitation is 132 cm per year (Boring 2001).
71
Longleaf pine woodlands and limesink wetlands are the dominant habitat types at
Ichauway. Other habitats include mixed pine-hardwood areas, food plots, agricultural fields,
slash pine (P. elliottii) flatwoods, riparian hardwood hammocks, oak sandhill barrens, natural
and old-field loblolly pine (P. taeda) stands, grassy and cypress-gum (Taxodium ascendens,
Nyssa biflora) limesink ponds, creek swamps, forested wetlands, riverine areas, shrub-scrub
upland, and human/cultural (i.e., resident quarters) areas (Boring 2001). The understory is
dominated by wiregrass and old-field grasses (e.g., Andropogon spp.), but >1,000 vascular plant
species occur on the site (Goebel et al. 1997, Drew et al. 1998). Approximately 24 km of the
Ichawaynochaway Creek flows through the study area, and the Flint River forms almost 22 km
of Ichauway’s eastern boundary (Boring 2001).
The site is divided into multiple-use and conservation zones interspersed throughout the
land area. Multiple-use zones comprise approximately 60% of Ichauway, and prescribed fire,
supplemental feeding, and maintenance of food plots are the primary management activities in
multiple-use zones. Conservation zones, comprising the remaining 40% of the land area, are
managed for longleaf pine restoration. Bobcats occur in both zones on Ichauway.
Much of Ichauway is managed for the longleaf pine-wiregrass ecosystem with prescribed
fire. Burning is performed on a 2-year rotation, usually during winter and early spring, on
approximately 4,000 to 6,000 ha throughout the entire site (Godbois et al. 2004). Prescribed
burning is used to control understory vegetation, reduce hardwoods, manage wildlife habitat,
reduce fuel buildup, promote wiregrass seed production, prepare sites for pine regeneration, and
for experimental research and educational activities (Boring 2001).
72
Food plots consisting of brown top millet (Brachiaria ramose), winter wheat (Triticum
aestivum), cowpea (Vigna spp.), grain sorghum (Sorghum vulgare), and Egyptian wheat
(Sorghum spp.) comprise 20% of the property (Godbois et al. 2004). Food plots occur less
abundantly in conservation zones than multiple use zones, and are typically planted for white-
tailed deer rather than quail. Supplemental feeding for quail with grain sorghum occurs in
multiple use zones at 2-week intervals between November and May (Godbois et al. 2004).
Fields are disked to improve quail food availability by allowing ragweed (Ambrosia
artemisiifolia) and partridge pea (Chamaecrista fasciculata) seedlings and other plants to grow
(Landers and Mueller 1986, Davis 2001).
Limited predator removal occurs in multiple use zones after the quail-hunting season
(March-May) annually. The primary predators removed are raccoons (Procyon lotor) and
opossums (Didelphis virginiana). Low numbers of coyote (Canis latrans), red fox (Vulpes
vulpes), gray fox (Urocyon cinereoargentus), and striped skunk (Mephitis mephitis) also are
removed each year. Bobcats were harvested occasionally before 1999, but since then have not
been harvested.
A variety of potential bobcat prey species are present at Ichauway. Small mammal
species include cotton rat, Eastern woodrat (Neotoma floridana), cotton mouse (Peromyscus
gossypinus), house mouse (Mus musculus), old-field mouse (P. polionotus), Eastern harvest
mouse (Reithrodontomys humulis), Southern short-tailed shrew (Blarina carolinensis) and least
shrew (Cryptotis parva) (Cochrane 2003). Eastern cottontail and marsh rabbit (S. palustris) are
present, and four species of sciurids are present (Eastern chipmunk [Tamias striatus], Southern
flying squirrel [Glaucomys volans], Eastern gray squirrel [Sciurus carolinensis], and fox squirrel
[S. niger].
73
METHODS
We collected scats on 30, 1-km long road transects once per month from June 2001-June
2004. Scat lines were assigned on secondary (frequently traveled, dirt roads) and tertiary (less
traveled, covered in grass) roads distributed throughout the study area. We also collected scats
opportunistically on the entire study area. Each sample was placed in a brown paper bag, labeled
with the date and location of collection, and frozen until processing. We collected ≥30 scats per
calendar season when possible (summer, fall, winter, spring).
Before processing, we thawed samples for 24 hours and oven-dried them for 72 hours at
60ºC (Baker et al. 1993, Griffin 2001). After weighing the samples, scats were sorted
macroscopically to separate and identify components (Baker et al. 1993). When possible, prey
items were identified to species using hair (Stains 1958), bone, teeth, and feathers (Baker et al.
1993). We categorized scat components into five major prey groups—rodent, bird, rabbit, deer,
and other (e.g., vegetation, opossum, raccoon, snake).
We calculated percent occurrence (i.e., frequency of occurrence divided by the total
number of scats examined within each season) for each prey category. We used a chi-squared
test of independence (Dowdy and Wearden 1991) in SAS (SAS Institute, Inc. 2003) to determine
if diet was dependent on year, and if diet varied seasonally within each year. We considered
statistical significance at α=0.10.
RESULTS
We collected 413 scats between 21 June 2001 and 20 June 2004 (n = 135 year 1, n = 130
year 2, n = 148 year 3). Bobcat diet varied among years (χ28 = 47.105, P < 0.001). The amount
of rodent and bird decreased from year 1 to year 2, and also decreased from year 2 to year 3.
74
Consumption of rabbit and other prey increased from year 1 to year 2, and from year 2 to year 3
(Figure 4.1). Deer decreased from year 1 to year 2, but increased from year 2 to year 3. Rodent
comprised 75.1% of all scats sorted, followed by: other (21.8%), rabbit (20.6%), bird (13.1%)
and deer (7.8%). Cotton rats comprised most (i.e., >60%) of the rodent category during all years
(year 1 = 74.0%; year 2 = 89.1%; year 3 = 61.6%). Northern bobwhite comprised 1.9% of all
samples analyzed (year 1 = 1.5%; year 2 = 2.3%; year 3 = 2.0%). Diet varied among seasons
during years 1 (χ212 = 19.934, P = 0.068; Figure 4.2) and 2 (χ2
12 = 23.674, P = 0.023; Figure 4.3),
but not during year 3 (χ212 = 17.352, P = 0.137; Figure 4.4). Species that comprised the other
category were: snake, raccoon, opossum, armadillo (Dasypus novemcinctus), skunk, bobcat, and
vegetation. For all years, vegetation (e.g., grass, seeds) was the most common food item in the
other category (year 1 = 37.5%; year 2 = 32.3%; year 3 = 86.1%).
DISCUSSION
Similar to other studies of bobcat diets in the southeastern U.S., bobcats in our study
primarily consumed rodents, rabbits, and other species (Davis 1955, Progulske 1955, Kight
1962, Beasom and Moore 1977, Miller and Speake 1978, Fritts and Sealander 1978, Kitchings
and Story 1979, Buttrey 1979, Fox and Fox 1982, Maehr and Brady 1986, Chamberlain and
Leopold 1999, Baker et al. 2001, Griffin 2001, Schoch 2003; Figure 4.5 and Table 4.1). Prey
selection is influenced by size, abundance, and energy returns associated with particular prey
species (Rosenzweig 1966, McCord and Cordoza 1982, Anderson and Lovallo 2003). Bobcats
are an opportunistic predator, but they may exhibit a functional response according to prey
availability and thus, are not purely opportunistic (McCord and Cordoza 1982, Baker et al. 2001,
Anderson and Lovallo 2003).
75
Among all years, rodent consumption decreased while rabbit consumption increased. An
overall increase in the rabbit population was a possible explanation for this occurrence;
however, we did not determine rodent or rabbit abundance during the study. Consumption of
prey in the other category also increased among all years, which may also reflect the
opportunistic nature of bobcat feeding habits. Vegetation was the most common food item in the
other category of bobcat prey species, probably ingested accidentally or intentionally as a
purgative (Miller and Speake 1978, Buttrey 1979).
During year 1, seasonal variation in bobcat diet was probably due to the increase in prey
consumption in the rabbit and other categories, particularly the increase from the winter to spring
seasons. Also, there were no rabbits consumed during the fall season, though rodent
consumption was highest during fall. Bird and deer were consumed more during the summer
season than any other seasons, possibly due to the presence of immature birds (nestlings and
fledglings), migratory bird species that are not present during other seasons, and fawns.
Seasonal variation during year 2 was likely due to the change in winter diet. While
rodent consumption declined and bird consumption was absent, deer and rabbit consumption
were higher than during any other season. Rabbit abundance may have increased during that
time period, and on Ichauway, rodent populations were generally lower during fall and winter
months (L.M. Conner, Joseph W. Jones Ecological Research Center, unpublished data).
There was no seasonal variation during year 3. Rodent consumption was lower overall
compared to other years, but it remained fairly constant during all seasons. Because overall bird
and deer consumption was low during summer, fall and winter, seasonal variation did not occur
despite a lack of consumption during the spring for both species. Rabbits and prey in the other
category fluctuated seasonally, but changes in consumption were not variable.
76
During all seasons and all years, rodents were the most common prey of bobcats on
Ichauway, which perhaps reflected the high rodent availability relative to other prey species
(Cochrane 2003). Management practices used for longleaf pine forest and quail management
may improve habitat for rodents (Cochrane 2003). On our study site, prescribed fire was a
primary land management tool, which increases and maintains a dense herbaceous understory
and early successional habitat, thereby providing abundant resources and habitat for prey
populations (Golley et al. 1965, Miller and Speake 1979). Planting agricultural crops and
maintaining quail food plots increases edge, which also provides ample resources for rodents
(Hall and Newsom 1976, Miller and Speake 1978).
Supplemental feeding increases prey abundance and concentrates prey (Boutin 1990).
Approximately 270 metric tons of grain sorghum are spread annually over 7,020 ha throughout
areas on our study site that are managed for quail between November and May (Godbois et al.,
2004). In a preliminary analysis of small mammal data collected at Ichauway, cotton rats were
5.5 more times abundant, cotton mouse were 1.5 times greater, Eastern harvest mouse were 2
times greater, and house mouse were 3.5 more times abundant in supplementally-fed versus
unfed areas (L.M. Conner, Joseph W. Jones Ecological Research Center, unpublished data).
Thus, current land management practices on Ichauway may have indirectly influenced bobcat
diets by providing abundant resources for rodent prey species, which resulted in more dense
rodent populations.
Contrary to other studies of bobcat diets in the Southeast, deer were consumed least
frequently during all years. Low deer consumption was probably influenced by the low density
of deer on the study area (4/km2), and because deer are more difficult to capture than rodents and
other prey species (Cochrane 2003).
77
In addition, deer may have been under-represented in scats, depending on length of exposure in
the field after deposition (Godbois et al. 2004b). Throughout the study, birds also were not a
major prey item. Fifty-four out of 413 scat samples contained bird remains, and only eight of the
bird remains were quail. Our findings were similar to Miller and Speake (1978), in which quail
comprised only two of 218 bobcat scats sampled from two quail plantations in Alabama. In
contrast, Schoch (2003) found quail remains (i.e., feathers or eggs) in seven of 66 bobcat
stomachs collected on a quail plantation in Georgia. Similar to our results, rodents were the
primary prey items for both of these studies, despite high densities of quail on the study areas.
Bobcats were not a primary predator of quail in our study. Although land management
practices such as prescribed fire, crop planting, maintenance of food plots, and supplemental
feeding are beneficial to quail, they also attract rodents and other species (Stoddard 1931).
Snakes and birds of prey, other potential quail predators, may be attracted to areas with dense
rodent populations. Cotton rats may compete with quail for food sources directly, and they
damage plants used by quail (Simpson 1976). Cotton rats also destroy northern bobwhite nests
(Stoddard 1931, Simpson 1976, Staller 2001). At Ichauway, bobcats were 10 times closer to
supplemental food than expected (Godbois et al. 2004a). Thus, in areas where densities of
cotton rats and other rodents are high, such as supplemental-feed areas and field edges, bobcats
may benefit quail by reducing populations of their competitors.
Further investigation of the relationships between bobcats, rodents, and quail is
necessary. Bobcat diet and prey abundance should be studied concurrently, to better explain
fluctuations in prey consumption annually and seasonally. Future studies of bobcat diet at
Ichauway should incorporate analysis using stomach or intestinal contents to better quantify the
presence of prey items that may be underrepresented in scat alone (e.g., deer and egg fragments).
78
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Thompson, and J. A. Chapman and, eds. Wild mammals of North America. Johns
Hopkins University Press, Baltimore, Maryland, USA.
Baker, L. A., R. J. Warren and W. E. James. 1993. Bobcat prey digestibility and
representations in scats. Proceedings of the Southeastern Association of Fish and
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_____, _____, D. R. Diefenbach, W. E. James, and M. J. Conroy. 2001. Prey
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the Catoosa wildlife management area. Pages 87-91 in Proceedings of the Bobcat
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Institute, Auburn, Alabama, USA. 79pp.
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NY, 629 pp.
Drew, M. B., L. K. Kirkman, and A. K. Gholson, Jr. 1997. The vascular flora of Ichauway,
Baker County, Georgia: a remnant longleaf pine/wiregrass ecosystem. Castanea 63:1-24.
Fox, L. B. and J. S. Fox. 1982. Population characteristics and food habits of bobcats in West
Virginia. Proceedings of the Southeastern Association of Fish and Wildlife Agencies
36:671-677.
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Fritts, S. H. and J. A. Sealander. 1978. Diets of bobcats in Arkansas with special reference to
age and sex differences. Journal of Wildlife Management 42:533-539.
Goebel, P. C., B. J. Palik, and L. K. Kirkman. 1997. Landscape ecosystem types of Ichauway.
Technical Report 97-1. Joseph W. Jones Ecological Research Center, Newton, Georgia,
USA.
Godbois, I. A., L. M. Conner, and R. J. Warren. 2004a. Space-use patterns of bobcats relative
to supplemental feeding of northern bobwhites. Journal of Wildlife Management 68:514-
518.
_____, L. M. Conner, B. D. Leopold, and R. J. Warren. 2004b. Bobcat scat exposure and
degradation: Effects on prey composition analysis. Wildlife Society Bulletin 32:In Press.
Golley, F. B., J. B. Gentry, L. D. Caldwell, and L. B. Davenport. 1965. Number and variety of
small mammals on the AEC Savannah River Plant. Journal of Mammalogy 46:1-18.
Griffin, J. C. 2001. Bobcat ecology on developed and less-developed portions of Kiawah
Island, South Carolina. Master Thesis, University of Georgia, Athens, GA. 84pp.
Hall, H. T. and J. D. Newsom. 1976. Summer home ranges and movements of bobcats in
bottomland hardwoods of southern Louisiana. Proceedings of the Annual Conference of
Fish and Wildlife Agencies 30:427-436.
Kight, J. 1962. An ecological study of the bobcat, Lynx rufus, in west-central South Carolina.
Master Thesis, University of Georgia, Athens, GA 52pp.
Kitchings, J. T., and J. D. Story. 1979. Home range and diet of bobcats in eastern Tennessee.
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Landers, J. L. and B. S. Mueller. 1986. Bobwhite quail management: a habitat approach. Tall
Timbers Research Station and Quail Unlimited, Tallahassee, Florida, USA.
Litvaitis, J. A., C. L. Stevens, and W. W. Mautz. 1984. Age, sex, and weight of bobcats in
relation to winter diets. Journal of Wildlife Management 48:632-635.
Maehr, D. S, and J. R. Brady. 1986. Food habits of bobcats in Florida. Journal of Mammalogy
67:133-138.
McCord, C. M. and J. E. Cordoza. 1982. Bobcat and lynx. Pages 728-766 in J. A. Chapman
and G. A. Feldhamer, eds. Wild Mammals of North America. Johns Hopkins University
Press, Baltimore, Maryland, USA.
Miller, S. D., and D. W. Speake. 1978. Prey utilization on quail plantations in southern
Alabama. Proceedings of Southeastern Association of Fish and Wildlife Agencies
32:100-111.
_____ and _____. 1979. Progress report: Demography and home range of the bobcat in south
Alabama. Pages 123-124 in L. G. Blum and P. C. Escherich, eds. Proceedings of the
bobcat research conference. National Wildlife Federation Scientific and Technical
Series 6.
Progulske, D. R. 1955. Game animals utilized as food by bobcat in the southern Appalachians.
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Rosenzweig, M. L. 1966. Community structure of sympatric Carnivora. Journal of
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Schoch, B. N. 2003. Diet, age, and reproduction of mesomammalian predators in response to
intensive removal during the quail nesting season. M. S. Thesis. University of Georgia,
Athens.
Simpson, R. C. 1976. Certain aspects of bobwhite quail’s life history and population dynamics
in southwest Georgia. Technical Bulletin. Georgia Department of Natural Resources,
Atlanta, Georgia. 117pp.
Stains, H. J. 1958. Field key to guard hair of middle western furbearers. Journal of Wildlife
Management. 22:95-97.
Staller, E. L. 2001. Identifying predators and fates of northern bobwhite nests using miniature
video camera. M. S. Thesis. University of Georgia, Athens.
Stoddard, H. L. 1931. The Bobwhite Quail: Its Habits, Preservation and Increase
Charles Scribner’s Sons, New York. 559pp.
Story, J. D., W. J. Galbraith, and J. T. Kitchings. 1982. Food habits of bobcats in eastern
Tennessee. Journal of Tennessee Academic Science 57:29-32.
83
Figure 4.1. Annual percent occurrence of prey items consumed by bobcats based on scat
analysis on Ichauway, Baker County, Georgia, 2001-2004.
84
0
10
20
30
40
50
60
70
80
90
100
rodent bird deer rabbit other
prey category
% sc
at c
onta
inin
g ca
tego
ry
year 1year 2year 3
85
Figure 4.2. Seasonal percent occurrence of prey items consumed by bobcats based on analysis of
135 scats on Ichauway, Baker County, Georgia, 2001-2002.
86
0
10
20
30
40
50
60
70
80
90
100
rodent bird deer rabbit other
prey category
% sc
at c
onta
inin
g ca
tego
ry
summerfallwinterspring
87
Figure 4.3. Seasonal percent occurrence of prey items consumed by bobcats based on analysis of
130 scats on Ichauway, Baker County, Georgia, 2002-2003.
88
0
10
20
30
40
50
60
70
80
90
100
rodent bird deer rabbit other
prey category
% sc
at c
onta
inin
g ca
tego
ry
summerfallwinterspring
89
Figure 4.4. Seasonal percent occurrence of prey items consumed by bobcats based on analysis of
148 scats on Ichauway, Baker County, Georgia, 2003-2004.
90
0
10
20
30
40
50
60
70
80
90
100
rodent bird deer rabbit other
prey category
% sc
at c
onta
inin
g ca
tego
ry
summerfallwinterspring
91
Figure 4.5. Seasonal percent occurrence of prey items consumed by bobcats (S01=Summer
2001; F01=Fall 2001; W02=Winter 2002; S02=Spring 2002; Su02=Summer 2002; F02=Fall
2002; W03=Winter 2003; S03=Spring 2003; Su03=Summer 2003; F03=Fall 2003; W04=Winter
2004; S04=Spring 2004) based on analysis of 413 scats on Ichauway, Baker County, Georgia,
2001-2004.
92
0
10
20
30
40
50
60
70
80
90
100
Su01 F01 W02 S02 Su02 F02 W03 S03 Su03 F03 W04 S04
season
% sc
at c
onta
inin
g ca
tego
ry
rodentbirddeerrabbitother
93
Table 4.1. Studies documenting bobcat diet by percent occurrence in the southeastern United States, using the gastrointestinal tract (GI; stomach or intestines) or scat for analysis. ______________________________________________________________________________ Reference State n Rodent Bird Deer Rabbit Other Analysis Technique ______________________________________________________________________________
Davis,1955 AL 239 18.8 6.9 10.5 63.2 20.6 GIb
Progulske, 1955 VA 124 66.9 14.9 9.9 54.6 62.8 Scat
Kight, 1962 SC 317 65.6 21.8 0.0 43.8 29.0 Scat
Beasom and Moore, 1977 TX 125 96.5 18.5 3.0 23.0 13.0 GI
Fritts and Sealander, 1978 AR 150 21.0 8.0 7.0 39.0 52.0 GI
Miller and Speake, 1978 AL 273 49.1 10.0 9.5 29.3 38.5 GI
Miller and Speake, 1978 AL 218 87.2 15.6 1.4 37.6 43.6 Scat
Buttrey, 1979 TN 49 60.0 12.2 20.4 34.7 36.6 GI/Scat
Kitchings and Story, 1979 TN 31 46.5 7.0 19.5 68.5 46.5 Scat
Fox and Fox, 1982 WV 172 44.1 8.9 50.1 23.6 5.5 GI
Maehr and Brady, 1986 FL 413 42.4 18.7 2.4 85.5 25.7 GI
Chamberlain and Leopold, 1999a MS 591 21.6 15.3 28.2 13.0 Scat Baker et al., 2001 GA 357 15.7 7.8 36.4 46.2 13.2 Scat Griffin, 2001 SC 179 43.0 13.7 19.0 16.0 8.7 Scat Schoch, 2003 GA 66 62.1 10.6 9.1 28.8 18.2 GI This study GA 413 75.1 13.1 7.8 20.6 21.8 Scat ______________________________________________________________________________ aBird included in 'other' category.
94
CHAPTER 5
CONCLUSIONS AND MANAGEMENT IMPLICATIONS
95
Bobcats (Lynx rufus) are considered an apex predator in certain forested ecosystems of
the southeastern U.S., including the longleaf pine (Pinus palustris)-wiregrass (Aristida stricta)
ecosystem of southwestern Georgia (Conner et al. 2000). However, control of bobcats and other
mammalian predators is often suggested as a method to increase game bird species abundance.
Although bobcats have historically been considered a major predator of northern bobwhite
(quail; Colinus virginianus), few studies have specifically analyzed bobcat food habits in areas
managed for quail. Because quail hunting is an important cultural and economic tradition in the
Southeast, and quail management is an important part of the longleaf pine ecosystem, it is
important to understand the impacts of bobcats on quail (Boring 2001, Burger et al. 1999). Thus,
one of our main objectives was to quantify seasonal diets of bobcats in a longleaf pine forest
managed for northern bobwhite. Our other objectives were to determine if annual and seasonal
bobcat home ranges varied by season and sex, determine habitat use at 2 spatial scales and
compare habitat use between the sexes and among seasons, and determine whether activity status
and time-of-day influenced bobcat habitat use.
Only 8 out of 413 scats collected over 3 years contained quail remains. Although we
could not account for quail eggs due to the type of diet analysis technique we used, we concluded
that bobcats were not a major predator of quail. During all seasons and all years, rodents were
the most common prey of bobcats on Ichauway, likely due to high rodent abundance relative to
other prey species (Cochrane 2003). Management practices used for longleaf pine forest and
quail management may improve habitat for rodents. On our study site, prescribed fire was a
primary land management tool, which increases and maintains a dense herbaceous understory
and early successional habitat, thereby providing abundant resources and habitat for prey
populations (Golley et al. 1965, Miller and Speake 1979).
96
Planting agricultural crops and maintaining quail food plots increases edge, which also provides
ample resources for rodents (Hall and Newsom 1976, Miller and Speake 1978). Supplemental
feeding may concentrate rodent populations, and bobcats at Ichauway were 10 times closer than
expected to supplementally-fed versus non-fed areas (Godbois et al. 2004).
Although home ranges for male bobcats were larger than for females on our study site,
home ranges of both sexes were smaller than home ranges previously reported for the
southeastern United States (Buie et al. 1979, Kitchings and Story 1979, Hamilton 1982, Shiftlet
1984, Lancia et al. 1986, Rucker et al. 1989, Conner et al. 1992, Conner et al. 2001). Land
management practices such as prescribed burning and maintenance of food plots contributed to
high-quality habitat with ample prey, which likely contributed to smaller home range sizes of
bobcats on our study area. Female home range sizes varied seasonally. Between winter and
spring during all 3 years of the study, female home range sizes declined, which was likely due to
females denning and restricting their movements (Bailey 1974, Knick 1990). The smallest
female home range occurred during Summer 2002, which corresponded with the post-parturition
period for that year. Females probably restricted their movements to provide prey to their kittens
(Bailey 1979, Jackson and Jacobson 1987, Conner et al.1992). Home ranges increased between
summer and fall seasons, during which kittens become old enough to travel with their mother
(Bailey 1979). Seasonal variation in bobcat home range size also may be influenced by prey
availability and breeding behavior.
In the longleaf pine ecosystem of Ichauway, bobcats selected habitats to include in their
home range (Johnson's second order of selection), but did not select habitats within the home
range (Johnson's third order of selection). At Johnson's second order, female bobcats were closer
to all habitat types than expected.
97
Males were closer then expected to all habitat types except shrub/scrub and wetland, suggesting
a preference for edges (Conner et al. 2003). Thus, bobcats appeared to prefer edge when
establishing home ranges. Edge provides travel routes and access to hunting areas such as
agriculture fields, and it is typically where an abundance of prey is found (Landers and Mueller
1986).
Similar to other studies in the Southeast, our bobcats preferred agriculture (Cochrane
2003, Conner et al. 1992), mixed pine-hardwood (Cochrane 2003), pine (Conner et al. 1992), and
hardwood habitats (Hall and Newsom 1976, Lancia et al. 1986). Bobcats likely selected early
and mid-successional habitats due to prey abundance and availability. Cotton rats (Sigmodon
hispidus) and eastern cottontails (Sylvilagus floridanus), 2 primary bobcat prey species in the
Southeast, are most abundant in dense areas of early to mid-successional grass/forb-shrub
vegetation (Boyle and Fendley 1987). Agricultural areas also attract rodent and lagomorph
species (Cummings and Vessey 1994). Hardwood and mixed pine-hardwood habitats contain a
dense herbaceous understory and shrub interspersion necessary to provide essential cover for
prey species, and such habitats also provide bobcats with cover (Golley et al. 1965, Schnell
1968).
We expected active animals to select agriculture and other early-to-mid-successional
habitat types more than inactive animals. Because bobcats are considered a nocturnal and/or
crepuscular species, we also expected bobcats to prefer early-to-mid-successional habitats during
the nighttime and crepuscular periods. Activity at crepuscular time periods coincides with
activity peaks for rodents and lagomorphs, which are primary bobcat prey.
98
Contrary to our hypotheses, bobcats did not select habitat differently according to activity status
or time-of-day. Because bobcats selected early-to-mid-successional habitat types to include in
their home ranges and such habitats may provide dense herbaceous cover, resting animals (i.e.,
inactive) likely did not have to find cover in other habitat types. If preferred habitats provided
ample prey and resting sites, then bobcats probably did not have to move to other habitats during
periods of rest or at different times throughout the diel period.
We suggest that bobcat habitat selection is probably determined by prey availability.
Habitat should be managed to provide a dense herbaceous layer for prey and bobcats. Prescribed
fire can accomplish this goal within the longleaf pine ecosystem. In addition, managing for a
mosaic of diverse habitat types increases the amount of edge available, which is an important
component of bobcat habitat.
Bobcat den sites have been discovered in hollow logs, rocky outcrops (Gashwiler et al.
1961, Cochrane 2003), at the base of tree stumps in timber-harvested areas (Kitchings and Story
1984), and in thickets and brush piles (Anderson 1987, Cochrane 2003). Den sites in human-
made structures, such as abandoned buildings, also have been observed (Bailey 1974). Three of
the 5 dens located were in bulldozed piles of trees and brush, by-products of human activities.
Den site selection is probably determined by protection from environmental conditions, and
possibly prey availability, since females are limited to hunting prey in close proximity to
unprotected kittens (Bailey 1979). Prescribed burning may create thickets and hollow stumps,
thereby increasing the availability of den sites for bobcats (Young 1958, Kitchings and Story
1984).
99
During the study, 14 confirmed bobcat mortalities occurred. Eight of the mortalities were
human-related (5 trapped and/or killed off-site; 3 from vehicle collisions). One bobcat was
killed by another felid, and 4 bobcats died from unknown causes.
Similar to studies of bobcats in other ecosystems of the southeastern U.S., bobcat home
range size and habitat use within the longleaf pine ecosystem were influenced by prey
availability and abundance. Although bobcats were not a major predator of quail, further
investigation of the relationships between bobcats, rodents, and quail is necessary. Bobcat diet
and prey abundance should be studied concurrently, to better explain fluctuations in prey
consumption annually and seasonally. Future studies of bobcat diet at Ichauway should
incorporate analysis using scat and stomach or intestinal contents to better quantify the presence
of particular prey items that may be underrepresented in scat alone (e.g., deer and egg
fragments).
Although our results suggest that prescribed burning and other quail management
practices may impact bobcat ecology, future research on Ichauway should document prey
population densities and bobcat locations in burned versus non-burned areas and in food plots
versus non-food plots, which might provide stronger evidence of the role land management
practices play in bobcat ecology in the longleaf pine forest.
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_____, B. D. Leopold, and M. J. Chamberlain. 2000. Multivariate habitat models for bobcats in
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_____ and B. D. Leopold. 2001. Spatio-Temporal relationships among adult bobcats in central
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_____, M. D. Smith, and L. W. Burger. 2003. A comparison of distance-based and
classification-based analyses of habitat use. Ecology 84:526-531.
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white-footed mice (Peromyscus leucopus). American Midland Naturalist 132:209-218.
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supplemental feeding of northern bobwhites. Journal of Wildlife Management 68:514-
518.
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small mammals on the AEC Savannah River Plant. Journal of Mammalogy 46:1-18.
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bottomland hardwoods of southern Louisiana. Proceedings of the Annual Conference
Southeastern Association of Fish and Wildlife Agencies 30: 427-436.
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Hamilton, D. A. 1982. Ecology of the bobcat in Missouri. Thesis, University of Missouri,
Columbia, Missouri, USA. 152 pp.
Jackson, D. L. and H. A. Jacobson. 1987. Population ecology of the bobcat (Felis rufus) in
managed southern forest ecosystems. Final Report Federal Aid Project, W-48-30, 31, 32,
33, 32. Mississippi Department of Wildlife Conservation Study XX. 69 pp.
Kitchings, J. T. and J. D. Story. 1979. Home range and diets of adult bobcats in eastern
Tennessee. Pages 47- 52 in L. G. Blum and P. C. Escherich, eds. Proceedings of the
bobcat research conference. National Wildlife Federation Scientific and Technical Series
6.
_____ and _____. 1984. Movements and dispersal of bobcats in eastern Tennessee. Journal of
Wildlife Management 48:957-961.
Knick, S. T. 1990. Ecology of bobcats relative to exploitation and a prey decline in southeastern
Idaho. Wildlife Monographs 108. 42 pp.
Lancia, R. A., D. K. Woodward, and S. D. Miller. 1986. Summer movement patterns and
habitat use by bobcats on Croatan National Forest, North Carolina. Pages 425-436 in:
S. D. Miller and D. D. Everett, (eds.). Cats of the world: biology, conservation, and
management. Caesar Kleberg Wildlife Research Institute, Kingsville, Texas, USA.
Landers, J. L. and B. S. Mueller. 1986. Bobwhite quail management: a habitat approach.
Tall Timbers Research Station and Quail Unlimited, Tallahassee, Florida, USA.
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103
_____ and _____. 1979. Progress report: Demography and home range of the bobcat in south
Alabama. Pages 123-124 in L. G. Blum and P. C. Escherich, eds. Proceedings of the
bobcat research conference. National Wildlife Federation Scientific and Technical
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Rucker, R. A., M. L. Kennedy, G. A. Heidt, and M. J. Harvey. 1989. Population density,
movements, and habitat use of bobcats in Arkansas. Southwestern Naturalist 34:101-108.
Schnell, J. H. 1968. The limiting effects of natural predation on experimental cotton rat
populations. Journal of Wildlife Management 32:698-711.
Shiftlet, B. L. 1984. Movements, activity, and habitat use of the bobcat in upland mixed pine-
hardwoods. Thesis, Louisiana State University, Baton Rouge, Louisiana, USA.
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193 pp.
104
APPENDIX A
MANAGEMENT ZONES ON ICHAUWAY, BAKER COUNTY, GEORGIA, 2000-2004
105
Conservation zones (40% of property) are managed with prescribed burning for longleaf pine
restoration. Multiple-use zones (60% of property) are managed with prescribed burning,
maintenance of food plots, supplemental feeding, and some predator control for northern
bobwhite.
106
APPENDIX B
MORPHOLOGICAL DATA COLLECTED FOR 50 ADULT BOBCATS
CAPTURED AND RADIO-COLLARED BETWEEN
DECEMBER 2000 AND MAY 2004, ICHAUWAY, BAKER COUNTY, GEORGIA
107
Morphological data collected for 50 adult bobcats captured and radio-collared between December 2000 and May 2004, Ichauway, Baker County, Georgia. ______________________________________________________________________________ Date Cat # Sexa Wtb Total Tail Hind Front (kg) length (cm) length (cm) foot length of ear (cm) length (cm) ______________________________________________________________________________
12/13/00 01 F 5.75 860 150 165 65 01/10/01 04 F 6.75 902 143 160 61 01/24/01 10 F 7.33 902 152 164 59 01/25/01 12 M 7.00 932 125 160 58 02/07/01 15 F 6.25 917 138 154 54 02/07/01 16 M 9.50 941 132 170 62 03/08/01 18 F 6.75 890 135 165 60 03/27/01 23 F 7.25 912 121 168 66 04/08/01 25 F 7.75 880 130 170 70 04/20/01 27 F 7.00 915 131 170 64 04/24/01 28 F 6.75 890 138 161 62 05/01/01 30 M 7.00 954 142 179 62 06/03/01 34 M 8.10 1000 170 170 70 06/04/01 05 M 5.60 940 160 160 60 11/16/01 36 M 10.50 1040 160 185 70 12/07/01 37 F 6.50 863 113 150 62 12/19/01 39 F 7.83 850 130 165 70 12/26/01 41 M 10.00 1010 140 175 70 03/05/02 06 F 7.40 940 145 160 60 03/05/02 45 M 8.50 1040 150 170 70 03/06/02 47 F 7.00 850 120 160 60 03/07/02 40 F 6.50 905 145 160 65 03/09/02 50 M 7.25 985 160 170 65 03/26/02 46 M 8.45 970 145 165 60 04/30/02 48 F 6.50 870 140 153 68 05/15/02 42 F 6.25 895 140 160 60 06/21/02 51 F 7.25 940 155 170 65 12/04/02 49 F 6.30 860 121 164 57 12/12/02 54 F 6.20 900 130 165 51 12/13/02 57 M 10.20 985 165 180 49 01/30/03 60 F 8.75 844 137 173 52 01/30/03 61 M 6.75 985 145 182 55 02/17/03 65 M 9.95 940 140 173 58 03/04/03 67 F 5.50 908 135 165 51 _____________________________________________________________________________
108
______________________________________________________________________________
Date Cat # Sexa Wtb Total Tail Hind Front (kg) length (cm) length (cm) foot length of ear (cm) length (cm) ______________________________________________________________________________
04/25/03 71 M 9.95 995 155 175 55 05/21/03 72 F 5.50 865 140 155 55 12/16/03 75 M 6.75 964 152 172 57 12/20/03 76 F 6.50 898 138 162 51 01/11/04 31 M 11.3 1047 180 180 64 01/21/04 80 F 6.55 935 152 175 62 01/28/04 82 F 6.50 870 152 164 70 02/01/04 83 M 10.30 985 140 179 70 03/11/04 11 M 7.50 966 166 174 58 03/18/04 53 M 8.75 1019 177 173 70 04/13/04 44 F 6.00 884 119 169 74 04/21/04 89 F 6.75 900 110 158 62 05/08/04 86 F 5.75 910 142 161 65 05/14/04 66 F 5.00 860 138 155 68 05/27/04 77 F 5.40 866 140 161 55 05/30/04 90 F 7.75 912 116 154 58 ______________________________________________________________________________ aF = Female; M = Male. bWeight.
109
APPENDIX C
ANNUAL AND SEASONAL
ADAPTIVE KERNEL (ADK) AND MINIMUM CONVEX POLYGON (MCP)
HOME RANGE SIZE ESTIMATES FOR BOBCATS ON
ICHAUWAY, BAKER COUNTY, GEORGIA, 2001-2004
110
Mean seasonal and annual home range sizes (km2) for 44 bobcats on Ichauway, Baker County, Georgia, 2001-2004, according to sex and home range estimator. ______________________________________________________________________________ Season/Year ADKa Estimate MCPb Estimate ______________ ______________ M F M F ______________________________________________________________________________
Fall 2001 2.1 5.1 2.6 3.0
Winter 2002 15.9 4.0 4.0 2.5
Spring 2002 8.1 3.3 4.4 1.8
Summer 2002 3.7 2.8 6.7 1.8
Fall 2002 7.2 5.6 4.9 3.3
Winter 2003 11.1 8.5 6.6 4.5
Spring 2003 10.5 4.5 6.6 2.8
Summer 2003 7.9 6.1 4.8 3.9
Fall 2003 6.6 5.9 4.0 3.6
Winter 2004 11.3 7.1 6.9 4.2
Spring 2004 9.6 5.6 6.5 3.7
All Seasonsc 8.5 5.3 5.3 3.2
Annual 2002-2003d 10.0 4.3 7.1 3.3
Annual 2003-2004d 12.3 8.1 9.7 6.9 All Yearse 11.2 6.2 8.4 5.1 ______________________________________________________________________________
a95% Adaptive Kernel. b95% Minimum Convex Polygon. cMean home range for all seasons pooled. dMean annual home range from Spring 2002-Winter 2003 and Spring 2003-Winter 2004. eMean annual home range for both years pooled.
111
Individual 95% adaptive kernel and 95% minimum convex polygon annual home range estimates (km2) for 44 bobcats on Ichauway, Baker County, Georgia, 2001-2004 (a minimum of 30 locations/bobcat/season for 4 consecutive seasons were obtained for analysis) ______________________________________________________________________________ Cat # Sexa ADKb Estimate MCPc Estimate __________________ __________________ Year 1d Year 2e Year 1 Year 2 ______________________________________________________________________________
01 F 2.9 2.2 04 F 4.0 3.3 10 F 5.2 4.3 23 F 4.4 3.4 36 M 9.8 7.7 41 M 13.3 10.1 15 F 3.1 6.8 2.3 5.2 18 F 6.1 7.2 44.8 5.9 25 F 6.5 9.7 4.2 7.1 34 M 12.0 16.1 7.3 12.8 37 F 2.9 5.3 2.7 3.6 39 F 4.7 7.9 3.4 5.8 45 M 5.0 7.6 3.5 5.3 47 F 3.4 4.7 2.6 3.6 06 F 5.0 3.8 42 F 6.5 5.3 49 F 5.5 4.7 60 F 25.0 26.7 63 F 4.9 3.7 67 F 8.2 6.6 71 M 13.4 10.9 ______________________________________________________________________________ aF = Female; M = Male b95% Adaptive Kernel. cMinimum Convex Polygon. dMean annual home range from Spring 2002-Winter 2003. eMean annual home range from Spring 2003-Winter 2004.
112
Individual 95% adaptive kernel seasonal home range estimates (km2; F01=Fall 2001; W02=Winter 2002; S02=Spring 2002; Su02=Summer 2002; F02=Fall 2002; W03=Winter 2003; S03=Spring 2003; Su03=Summer 2003; F03=Fall 2003; W04=Winter 2004; S04=Spring 2004) for 44 bobcats on Ichauway, Baker County, Georgia, 2001-2004 (a minimum of 30 locations/bobcat/season were obtained for analysis) ______________________________________________________________________________ Cat # Sex F01 W02 S02 Su02 F02 W03 S03 Su03 F03 W04 S04 ______________________________________________________________________________ 01 F 5.0 1.4 1.2 1.8 3.9 5.9 4.3 5.4 04 F 3.5 3.1 4.0 3.5 4.3 4.2 7.6 4.3 05 M 4.6 3.1 3.0 06 F 3.1 3.6 17.5 3.1 2.9 4.2 5.1 5.5 10 F 3.9 4.3 1.2 3.2 2.7 6.1 7.7 13.8 7.8 11 M 10.7 15 F 2.8 1.6 2.7 1.2 3.8 3.4 3.0 4.5 5.2 9.6 7.2 16 M 5.6 2.8 3.4 4.3 5.1 18 F 4.6 1.6 3.8 3.9 5.6 14.0 4.9 6.7 4.7 7.1 3.4 23 F 4.5 4.8 5.5 2.0 3.7 9.5 3.0 9.9 7.9 25 F 1.2 1.7 3.7 1.3 6.6 6.3 7.2 12.3 8.3 8.3 6.1 26 F 2.2 27 F 18.4 14.2 1.0 6.7 7.4 30 M 3.2 80.1 9.8 8.8 8.5 9.0 31 M 5.9 6.4 34 M 5.4 5.7 6.8 4.1 4.3 17.5 10.7 9.8 9.0 17.6 19.4 36 M 1.2 5.2 6.8 9.8 8.3 7.9 5.9 8.7 37 F 2.1 2.7 2.0 1.7 2.7 1.5 3.5 4.4 5.4 6.0 39 F 5.7 5.4 2.6 2.4 6.7 4.2 6.7 7.7 6.8 4.0 40 F 6.0 31.0 34.7 7.8 41 M 6.2 3.1 6.2 11.9 13.0 13.5 9.0 6.0 42 F 3.0 5.7 5.3 3.2 4.3 6.5 6.6 6.8 44 F 3.5 45 M 2.4 3.7 3.1 4.3 8.8 8.5 5.3 5.8 5.2 46 M 0.7 47 F 3.3 2.0 1.7 4.2 3.1 3.3 5.9 5.1 3.2 48 F 6.1 49 F 3.1 3.1 7.4 4.2 5.3 3.4 51 F 0.8 3.6 53 M 7.2 57 M 16.4 9.1 7.4 ______________________________________________________________________________
113
______________________________________________________________________________ Cat # Sexa F01 W02 S02 Su02 F02 W03 S03 Su03 F03 W04 S04 ______________________________________________________________________________ 60 F 3.9 6.9 8.1 5.9 9.3 10.2 61 M 10.1 9.2 6.9 63 F 6.7 3.6 3.7 2.4 3.1 65 M 6.5 3.5 66 F 4.9 67 F 3.1 4.5 6.0 7.7 5.5 71 M 13.4 8.5 8.7 15.8 10.4 75 M 19.5 80 F 3.0 2.0 82 F 8.9 9.7 83 M 4.2 3.7 86 F 5.7 89 F 10.3 ______________________________________________________________________________ aF = Female; M = Male
114
Individual 95% minimum convex polygon seasonal home range estimates (km2; F01=Fall 2001; W02=Winter 2002; S02=Spring 2002; Su02=Summer 2002; F02=Fall 2002; W03=Winter 2003; S03=Spring 2003; Su03=Summer 2003; F03=Fall 2003; W04=Winter 2004; S04=Spring 2004) for 44 bobcats on Ichauway, Baker County, Georgia, 2001-2004 (a minimum of 30 locations/bobcat/season were obtained for analysis) ______________________________________________________________________________ Cat # Sex F01 W02 S02 Su02 F02 W03 S03 Su03 F03 W04 S04 ______________________________________________________________________________ 1 F 2.5 0.8 0.7 1.3 2.0 2.8 2.5 2.0 4 F 2.0 1.6 2.3 2.4 2.5 2.5 2.7 4.2 3.5 5 M 2.6 1.3 2.1 6 F 1.5 2.0 7.7 1.9 1.8 2.6 3.6 3.9 10 F 2.5 2.6 0.6 1.9 1.7 3.5 6.0 13.8 7.8 11 M 8.3 15 F 1.8 1.1 1.4 0.8 2.2 2.0 1.9 3.2 3.2 5.5 4.4 16 M 3.6 1.8 1.6 24.3 3.2 18 F 2.8 1.0 2.3 2.5 3.0 5.7 3.0 4.4 2.4 3.7 2.5 23 F 3.1 3.3 3.8 1.3 2.4 3.0 5.7 7.0 4.6 25 F 0.8 1.0 1.7 1.1 3.7 4.0 4.1 6.8 5.3 4.6 2.8 26 F 1.3 27 F 10.7 9.3 0.4 4.4 4.7 30 M 2.2 14.7 5.6 38.3 5.6 5.6 5.2 31 M 2.8 4.4 34 M 3.8 3.9 5.4 3.2 3.6 9.9 7.4 6.1 6.5 14.5 13.9 36 M 0.7 3.2 6.3 6.9 5.1 4.8 3.7 5.5 37 F 1.1 1.8 1.4 1.4 1.8 1.1 2.6 2.8 3.3 3.2 39 F 3.5 2.9 1.7 1.4 4.4 2.7 4.1 4.4 3.9 2.2 40 F 4.1 15.8 18.2 5.6 41 M 3.8 2.5 4.8 7.7 8.5 8.2 5.7 3.7 42 F 1.6 3.3 2.5 1.9 2.4 3.6 5.3 3.7 44 F 1.9 45 M 1.3 1.7 2.2 2.5 7.5 4.3 3.2 3.1 3.0 46 M 0.4 47 F 1.4 1.4 1.4 2.5 2.0 2.0 3.7 3.1 2.2 48 F 1.9 49 F 2.7 1.7 4.6 3.1 3.2 2.5 51 F 0.5 2.9 53 M 4.8 57 M 9.4 4.6 3.9 ______________________________________________________________________________
115
______________________________________________________________________________ Cat # Sex F01 W02 S02 Su02 F02 W03 S03 Su03 F03 W04 S04 ______________________________________________________________________________ 60 F 2.3 4.1 4.9 4.0 6.2 7.7 61 M 5.4 4.9 3.9 63 F 3.3 2.5 2.7 1.7 2.1 65 M 4.4 1.5 66 F 3.8 67 F 1.8 2.9 4.0 5.1 3.6 71 M 8.0 6.2 6.0 8.4 8.6 75 M 8.5 80 F 1.4 1.2 82 F 4.5 5.4 83 M 4.6 1.6 86 F 2.8 89 F 7.4 ______________________________________________________________________________ aF = Female; M = Male
116
APPENDIX D
DESCRIPTION OF FIVE BOBCAT DENS LOCATED IN A LONGLEAF PINE
ECOSYSTEM, ICHAUWAY, BAKER COUNTY, GEORGIA, 2002-2004
117
We confirmed location of five dens through the duration of the study. The first den was
located 17 April 2002 in a bulldozed pile of trees, stumps, and branches. The den was audibly
confirmed by the sound of least 2 kittens. The mother was observed in the den. Den 2 was
located 17 April 2003, in a brush pile bulldozed for logging, surrounded by briars and sassafras
(Sassafras spp.). At least two kittens were heard, but there was no visual confirmation of kittens
or adult. The third den was located 24 April 2003 in a hollowed-out water oak tree (Quercus
nigra) in a hardwood bottom close to the Flint River. Two kittens with closed eyes were
observed with the adult female. Den 4 was located 24 April 2003 in a fallen-down hollow log
surrounded by dense vegetation. At least 2 kittens were heard, and the adult female was
observed fleeing the den. The fifth den was located 30 April 2004 in a brush pile created as a
by-product of logging near a primary road. At least 1 kitten was heard, but there was no visual
confirmation of the kittens or mother.
118
APPENDIX E
DESCRIPTION OF BOBCAT MORTALITIES IN SOUTHWESTERN GEORGIA, 2001-2004
119
Mortality events for bobcats captured on Ichauway, Baker County, Georgia, 2001-2004 ____________________________________________________________________________________________________________ Cat # Sexa Ageb Date of initial Date of last Date of mortality Cause of Mortality capture radio-location ____________________________________________________________________________________________________________
07 F A 01/22/01 06/19/01 06/21/01 vehicle collision 14 M A 02/02/01 10/05/01 10/29/01 trapped off-site (LL Plantationc) 19 M A 03/14/01 N/Ad 05/24/02 unknown; dead in trap 03 M A 01/04/01 never relocated 09/27/01 trapped off-site (PB Plantatione) 26 M A 04/19/01 01/27/02 01/28/02 killed by another felid 32 M A 05/16/01 05/19/01 06/28/02 killed off-site (private plantation) 51 F A 06/21/02 10/27/02 12/3/02 unknown 54 F A 12/12/02 never relocated 12/30/02 unknown 16 M A 02/07/01 02/18/03 03/04/03 unknown - possibly vehicle collision 30 M A 05/21/01 07/02/03 07/08/03 unknown 36 M A 11/16/01 11/26/03 11/29/03 killed off-site (LL Plantation) 41 M A 01/26/02 12/19/03 12/26-12/28/03 vehicle collision 73 M J 05/30/03 N/A 01/28/04 trapped off-site (LL Plantation) 75 M A 12/16/03 04/14/04 04/29/04 probably trap injury; broken neck 83 M A 02/01/04 05/28/04 05/29/04 vehicle collision ____________________________________________________________________________________________________________ aF = Female; M = Male. bA = Adult; J = Juvenile. cLongleaf Plantation, located 3-4 miles away from Ichauway. dNot applicable to juvenile bobcats (not radio-collared) or bobcats recaptured as adults and not radio-collared during first capture.
ePinebloom Plantation, located >10 miles away from Ichauway.