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Bobcat Population Status and Management in North America: Evidence of Large-Scale Population Increase

DOI:10.3996/122009-JFWM-026
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Nathan M Roberts at College of the Ozarks
Nathan M Roberts
Shawn Crimmins at U.S. Geological Survey
Shawn Crimmins
  • U.S. Geological Survey
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Abstract

Bobcat Lynx rufus populations are thought to be increasing in North America; however, little information exists on their current population status. In the United States, management and monitoring of bobcat populations is the responsibility of state wildlife management agencies. We surveyed state wildlife management agencies in each of the 48 contiguous states regarding the current population status, distribution, and monitoring protocols of bobcats within each respective jurisdiction. We also surveyed the governments of Mexico and Canada regarding bobcat population status within their jurisdictions. We received responses from 47 U.S. states, Mexico, and 7 Canadian provinces. Responses indicate that bobcats occur in each of the contiguous states except for Delaware. Populations were reported to be stable or increasing in 40 states, with 6 states unable to report population trends and only 1 state (Florida) reporting decreases in bobcat populations. Of the 47 states in which bobcats occur, 41 employ some form of population monitoring. Population density estimates were available for 2,011,518 km2(33.6%) of the estimated bobcat range in the United States, with population estimates between 1,419,333 and 2,638,738 individuals for this portion of their range and an estimated 2,352,276 to 3,571,681 individuals for the entire United States. These results indicate that bobcat populations have increased throughout the majority of their range in North America since the late 1990s and that populations within the United States are much higher than previously suggested.
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Surveys
Bobcat Population Status and Management in North
America: Evidence of Large-Scale Population Increase
Nathan M. Roberts,* Shawn M. Crimmins
N.M. Roberts
Department of Natural Resources, Cornell University, Ithaca, New York 14853
S.M. Crimmins
Department of Forest Management, University of Montana, Missoula, Montana 59812
Abstract
Bobcat Lynx rufus populations are thought to be increasing in North America; however, little information exists
on their current population status. In the United States, management and monitoring of bobcat populations
is the responsibility of state wildlife management agencies. We surveyed state wildlife management agencies in
each of the 48 contiguous states regarding the current population status, distribution, and monitoring protocols
of bobcats within each respective jurisdiction. We also surveyed the governments of Mexico and Canada regarding
bobcat population status within their jurisdictions. We received responses from 47 U.S. states, Mexico, and 7
Canadian provinces. Responses indicate that bobcats occur in each of the contiguous states except for Delaware.
Populations were reported to be stable or increasing in 40 states, with 6 states unable to report population trends
and only 1 state (Florida) reporting decreases in bobcat populations. Of the 47 states in which bobcats occur, 41
employ some form of population monitoring. Population density estimates were available for 2,011,518 km
2
(33.6%) of
the estimated bobcat range in the United States, with population estimates between 1,419,333 and 2,638,738
individuals for this portion of their range and an estimated 2,352,276 to 3,571,681 individuals for the entire United
States. These results indicate that bobcat populations have increased throughout the majority of their range in North
America since the late 1990s and that populations within the United States are much higher than previously
suggested.
Keywords: bobcat; Lynx rufus; monitoring; North America; population status
Received: December 13, 2009; Accepted: June 10, 2010; Published Online Early: June 2010; Published: November
2010
Citation: Roberts NM, Crimmins SM. 2010. Bobcat population status and management in North America: evidence of
large-scale population increase. Journal of Fish and Wildlife Management 1(2):169–174; e1944-687X. doi: 10.3996/
122009-JFWM-026
Copyright: All material appearing in the Journal of Fish and Wildlife Management is in the public domain and may be
reproduced or copied without permission. Citation of the source, as given above, is requested.
The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the
U.S. Fish and Wildlife Service.
* Corresponding author: nmr25@cornell.edu
Introduction
Bobcats Lynx rufus are one of the most widely spread
and adaptable carnivores in North America (Anderson
1987). Bobcats serve as a top predator in many
ecosystems (Conner et al. 2001) and can have significant
effects on ecosystem function. For example, bobcats
have been identified as a significant source of predation,
in specific systems, for white-tailed deer Odocoileus
virginianus (Nelms et al. 2001), cotton rats Sigmodon
hispidus (Schnell 1968), and pronghorn Antilocapra
americana (Beale and Smith 1973). Thus, in many
situations, proper management of bobcat populations
may be an important component of managing for
ecosystem function and biodiversity.
In the United States, management of bobcat popula-
tions is the responsibility of state wildlife management
agencies. However, management of bobcats, as with
many other carnivores, can be difficult due to their
elusive nature and the lack of information on demo-
Journal of Fish and Wildlife Management | www.fwspubs.org November 2010 | Volume 1 | Issue 2 | 169
Table 1. Bobcat monitoring methods (Monitoring), population estimates (N), range extent (Habitat, in km
2
), and population
status (Status; 1981–present) for selected jurisdictions in North America. NR indicates data were not reported by jurisdiction.
Monitoring methods were public sightings (PS), harvest analysis (HA), hunter surveys (HS), population models (PM), scent or sign
stations (SS), snow track surveys (TS), incidental harvest (IH), vehicle collisions analysis (VC), or other (OT).
Jurisdiction Monitoring
N
Habitat Status
United States
Alabama HA 68,625 116,550 Increasing
Arizona HA,HS 62,395–65,909 294,315 Increasing
Arkansas HS 14,049 134,874 Unknown
California NR 69,429–72,735 330,614 Stable
Colorado NR NR NR NR
Connecticut PS,VC Unknown 11,655 Increasing
Delaware - 0 - Absent
Florida NR 303,338 151,669 Decreasing
Georgia HA,SS 209,870–249,845 149,907 Increasing
Idaho NR 1,705–13,640 170,500 Increasing
Illinois HS 2,252 143,960 Increasing
Indiana PS,IH Unknown 92,434 Increasing
Iowa PM,OT 1,155–2,331 34,153 Increasing
Kansas HA,HS,SS 29,666–31,785 211,900 Increasing
Kentucky HA 14,000 102,896 Increasing
Louisiana HA,HS 66,431 112,825 Increasing
Maine HA Unknown 40,000 Stable
Maryland SS Unknown Unknown Increasing
Massachusetts NR Unknown 12,051 Unknown
Michigan HS,SS Unknown 116,550 Increasing
Minnesota HA,PM,SS,TS 2,857 103,600 Increasing
Mississippi HA 52,436 90,753 Increasing
Missouri HA,HS,SS 18,000–20,000 121,489 Increasing
Montana HA,TS 7,641 375,550 Increasing
Nebraska NR Unknown 171,000 Increasing
Nevada HA,PM Unknown 284,449 Stable/Increasing
New Hampshire HS,VC,IH Unknown 20,098 Increasing
New Jersey OT 106 1,600 Increasing
New Mexico HA,SS 36,249–54,373 181,243 Stable
New York PS,HA,HS 5,078 103,600 Increasing
North Carolina HA 90,115 126,161 Increasing
North Dakota HA Unknown 36,838 Unknown
Ohio PS Unknown 22,286 Increasing
Oklahoma HA Unknown 178,202 Increasing
Oregon None Unknown 248,630 Unknown
Pennsylvania HA,VC,IH,PS,PM 18,766 85,300 Increasing
Rhode Island PS,VC Unknown Unknown Unknown
South Carolina HA,SS 40,552–94,622 56,773 Stable
South Dakota HA,PM Unknown 100,000 Increasing
Tennessee HA Unknown 106,739 Stable
Texas HA 287,444–1,357,928 495,594 Stable
Utah HA Unknown 202,020 Stable
Vermont HA 2,100–3,500 23,310 Increasing
Virginia HA Unknown 64,118 Increasing
Washington NR Unknown 170,000 Stable
West Virginia HA 8,743 56,656 Increasing
Wisconsin HA,HS,PM,TS 2,850 46,620 Increasing
Bobcat Status and Management in North America N.M. Roberts and S.M. Crimmins
Journal of Fish and Wildlife Management | www.fwspubs.org November 2010 | Volume 1 | Issue 2 | 170
graphic rates. Changes in bobcat management in
response to population trends are common (Rolley et
al. 2001); however, most population assessments or
studies of bobcat range have been limited in geographic
scope (e.g., Woolf et al. 2002). It is generally assumed by
managers that a harvest rate of 20% is sustainable (Knick
1990), but that variability in environmental factors may
confound this (Anderson and Lovallo 2003). The vast
geographic range of bobcats in North America highlights
the need for large-scale population assessments. Bluett
et al. (2001) reported that state agencies considered
distribution and relative abundance to be among the
most important research topics for bobcats.
Woolf and Hubert (1998) provided the most recent
assessment of bobcat population distribution and
management in North America, with the most recent
range-wide population assessment occurring in 1981
(USFS 1981). However a more contemporary assess-
ment is needed because human populations and
development have increased greatly during the past
decades. Although numerous regional or local studies
have suggested that bobcat populations are increasing
(e.g., Woolf et al. 2000), no empirical evidence of range-
wide increases in population abundance exists. Our
objective was to document monitoring efforts, spatial
distribution, and population trends of bobcats in North
America.
Methods
Agency surveys
We contacted wildlife management agencies from all
of the 48 contiguous states of the United States, 7
Canadian provinces (British Columbia, Manitoba, New
Brunswick, Nova Scotia, Ontario, Quebec, Saskatchewan),
and the country of Mexico in 2008. Each jurisdiction was
asked to report: 1) what methods are employed to
monitor bobcat status, 2) population estimates and
average densities (if available), 3) the area (reported here
in km
2
) of suitable bobcat habitat within the jurisdiction,
and 4) post-1981 population trends. Monitoring methods
were classified as public sightings, harvest analysis,
hunter surveys, population models, scent or sign
stations, snow track surveys, incidental harvest, vehicle
collisions analysis, or other. We primarily present
information from U.S. states to facilitate comparison
with previous studies and population estimates (USFWS
1982; Woolf and Hubert 1998) and for brevity.
Data analysis
We compared the proportion of states reporting
increasing or stable populations between 1996 and
2008 (Woolf and Hubert 1998) using chi-square tests. We
only included states that reported population trends in
this analysis. States that reported populations as ‘‘stable/
increasing’’ were assigned a status of ‘‘stable’’ for this
analysis. We estimated minimum population abundance
and total suitable habitat as the sum of population or
habitat estimates across all jurisdictions. Because not all
states reported estimated population abundance (n=
26) or area of suitable habitat (n= 5), we considered
these minimum estimates to be very conservative. To
estimate total population abundance across the contig-
uous United States, we calculated average bobcat
density for those states reporting both population and
area of habitat estimates and then multiplied this
average by the geographic range estimates for all states
that reported range estimates but no population
estimates (n= 17) and added this value to the minimum
count. This method provided a general estimate of
population abundance across the entire United States
that facilitates comparison with historic estimates that
used similar methods (USFWS 1982).
Results
We received responses from 47 of the 48 states, 7
Canadian provinces, and Mexico. Responses indicated
total area of suitable bobcat habitat of 8,708,888 km
2
,
with 71% (6,186,819 km
2
) in the United States, 20% in
Mexico (1,702,545 km
2
), and 9% in Canada (819,524 km
2
).
Twenty-eight (50.9%) of the jurisdictions reported
population estimates or densities (Table 1). Of the 48
jurisdictions that reported population trends, 31 (64.6%)
reported increasing populations while 15 (31.3%) report-
ed stable populations, and 1 reported fluctuating
populations. Only one jurisdiction, Florida, reported
decreasing bobcat populations (Figure 1). The minimum
population estimate in the United States was between
1,418,333 and 2,637,738 individuals, representing 68.4%
of the total estimated bobcat range in the United States
(Table 1). Using average density, the total population
Table 1. Continued.
Jurisdiction Monitoring
N
Habitat Status
Wyoming HA,SS 2,481–13,783 253,601 Increasing
Canada
British Columbia HA Unknown NR Stable
Manitoba NR Unknown NR Stable
New Brunswick HA,TS,OT Unknown 72,784 Stable
Nova Scotia HA,OT 5,170–9,910 43,086 Fluctuating
Ontario HA Unknown 400,015 Stable
Quebec PS,IH Unknown 55,000 Stable/Increasing
Saskatchewan HA,HS Unknown 248,639 Stable
Mexico NR Unknown 1,702,545 Unknown
Bobcat Status and Management in North America N.M. Roberts and S.M. Crimmins
Journal of Fish and Wildlife Management | www.fwspubs.org November 2010 | Volume 1 | Issue 2 | 171
abundance in the United States was estimated to be
between 2,352,276 and 3,571,681 individuals. A signifi-
cantly higher (x
2
= 5.64, P= 0.018, df = 1) proportion of
states reported increasing populations in 2008 than in
1996.
Of the 55 jurisdictions surveyed, 45 (81.2%) reported
methods used to monitor bobcat populations, 25 (55.6%)
of which used .1 method. Harvest data analysis and
hunter surveys were the most commonly used methods
(Table 2). No jurisdiction used .5 methods to monitor
bobcats. Only one jurisdiction (Oregon) reported having
bobcat populations but no monitoring method.
Discussion
Bobcats are highly adaptable carnivores and are the
most abundant of North America wild felids (Cowan
1971; Anderson and Lovallo 2003). Their ecological role
and economic value as furbearers are the primary
motivations behind research and management of
bobcats (Woolf and Nielsen 2001). Woolf and Hubert
(1998) reported that less than half of the states in the
contiguous United States (n= 20) had increasing bobcat
populations as of 1996; however, we found that 32 states
now report increasing populations (Table 1). All other
states that reported bobcat population trends, with the
exception of Florida, reported at least stable populations.
Although the magnitude of population increase likely
varies considerably among jurisdictions, the general trend
supports the hypothesis that bobcat populations are
expanding across much of their geographic range. The
reason for declining populations in Florida is unknown,
although extensive human development may be partly
responsible. Given the stability of bobcat populations
elsewhere in the United States, the decreasing population
in Florida does not pose any immediate threat to the
large-scale persistence of bobcat populations in the
United States. However, research into the vital rates and
demographic patterns of the Florida bobcat population
could provide useful information to wildlife managers if
populations elsewhere begin declining.
Minimum population estimates provided by jurisdic-
tions indicated that the United States’ bobcat population
is .1.4 million. This estimate is likely a substantial
underestimation of total population abundance, because
it only represented population estimates for approxi-
mately 68% of the reported bobcat range. In 1981 similar
methods were used to estimate bobcat populations; at
that time it was estimated there were 725,000–1,017,000
bobcats in the United States (USFWS 1982). Using these
methods, our data indicate that current bobcat popula-
tion abundance in the entire United States is 2,352,276–
3,571,681. This growth is likely the result of many factors
including changing agricultural and land-use practices,
range expansion, and habitat improvement programs
such as the Conservation Reserve Program (FSA 1985, 16
U.S.C. 3831). In addition, advances in wildlife manage-
ment and monitoring have allowed states to greatly
improve wildlife management programs in recent
decades, particularly furbearer management. As recently
as 1971, 40 of the 48 contiguous United States had no
protection or formal management of bobcats (Faulkner
1971). In New York, for example, bobcats were desig-
nated as an unprotected species and take was unregu-
lated through 1976, only 5 y prior to the 1981 population
estimate (USFWS 1982). After 1976, bobcats were
afforded legal status as a furbearer species to be
conserved, and harvest regulations were developed
and implemented. Similar shifts in management para-
digms have occurred in many jurisdictions; these have
clearly benefited bobcat populations. Bobcat harvests
did increase during 1976–1984, but recent harvest levels
are comparable to those three decades earlier (36,674
harvested during 1997–1998 verses 37,026 during 1975–
1976), despite this increase in population size (Associa-
tion of Fish and Wildlife Agencies, unpublished data).
This is likely due to decreased harvest effort.
Because population survey methods were not stan-
dardized across jurisdictions, there is likely substantial
variability in the accuracy of the estimates provided by
management agencies. For example, only six states used
any form of population model in their monitoring of
bobcat populations, likely because of the paucity of
accurate data available for developing such models.
Similarly, 19 states failed to report population estimates.
Although this variability may be substantial, it does not
preclude comparison to previous reports (USFWS 1982)
or interpretation of jurisdiction-specific population
Table 2. Methods used to monitor bobcat populations in
the lower 48 states and 7 Canadian provinces in 2008 (45
jurisdictions reporting). Twenty-five jurisdictions used .1
method.
Method No. of jurisdictions
Harvest data analysis 33
Public sightings 7
Hunter surveys 11
Population models 6
Scent or sign stations 9
Snow track surveys 4
Incidental harvest 4
Vehicle collision analysis 4
Other 4
None 1
Figure 1. Bobcat population trends in the contiguous United
States, 2004.
Bobcat Status and Management in North America N.M. Roberts and S.M. Crimmins
Journal of Fish and Wildlife Management | www.fwspubs.org November 2010 | Volume 1 | Issue 2 | 172
trends. Agency surveys such as this provide the only
feasible means of providing range-wide population
assessments, because field-based surveys would be
logistically and financially impractical. Although the level
of detail in such surveys is limited, they can provide a
cost-effective means to estimate large-scale population
trends. At the statewide scale, harvest surveys were the
most commonly used approach for monitoring bobcat
populations, which is not surprising given that these
data can be obtained for large geographic areas at
relatively low costs. Unlike harvest analysis or scent
stations, methods such as hunter surveys that do not
require market-based incentives or extensive field labor
may be more practical methods for monitoring bobcat
population trends.
As with many species, enumeration of population
abundance is not required for proper management.
Within jurisdictions, specific monitoring programs can be
implemented if needed. In the United States, 41 states
currently monitor bobcat population status or trends,
despite the fact that only one state reported bobcat
populations as declining. Population models, archer
surveys, hunter surveys, harvest data, field studies,
scent-post surveys, sign-station surveys, public sightings,
and detection dogs are all techniques used in North
America to monitor bobcat populations (Bluett et al.
2001; Anderson and Lovallo 2003). The majority of
jurisdictions that reported monitoring methods used
multiple methods (Table 2). The number of jurisdictions
monitoring bobcat populations, and the number of
methods used, is similar to previous reports (Woolf and
Hubert 1998). The number of jurisdictions reporting
increasing bobcat populations has increased from 20 to
32 since 1996 (Woolf and Hubert 1998), and overall
population estimates for the United States have more
than doubled since 1981 (USFWS 1981). Similarly, six of
the seven Canadian provinces reported stable bobcat
populations.
Bobcat populations are more widely distributed and
more abundant than they were in 1981. These increases
are likely attributable primarily to multiple factors
including habitat availability, increased prey density,
changing land-use practices, and intense harvest man-
agement at the state level. Standardization of monitoring
and density-estimation techniques would increase the
robustness of future comparisons. Thus, we suggest that
jurisdictions focus on developing standardized methods
for assessing bobcat distribution and abundance.
Acknowledgments
We thank the state, provincial, and national wildlife
management agencies for providing the data for this
analysis. The Ohio Division of Wildlife facilitated the
distribution and collection of the surveys. Logistical
support was provided by the Department of Natural
Resources at Cornell University and the Department of
Forest Management at the University of Montana. We
also thank the two anonymous reviewers and the
Subject Editor for providing valuable comments that
improved the quality of the manuscript.
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Journal of Fish and Wildlife Management | www.fwspubs.org November 2010 | Volume 1 | Issue 2 | 174
... Bobcats are widely distributed throughout Oklahoma, and their population is considered to be increasing (Roberts and Crimmins 2010). Large portions of Oklahoma contain overlapping distributions of both tick vectors, lone star ticks and the American dog ticks (Barrett et al. 2015;Mitcham et al. 2017), where bobcats are located. ...
... Bobcats are also widely distributed across North America, and estimates of their populations suggest that the number of bobcats have increased over time (Woolf and Hubert 1998;Roberts and Crimmins 2010). Bobcats range through a variety of habitats such as forest, savanna, shrubland, grassland, and desert (Kelly et al. 2016); studies have demonstrated that bobcat densities have a positive relationship with forest cover and high prey densities, and a negative relationship with extensively modified landscape (Donovan et al. 2011;Reding et al. 2013;Broman et al. 2014;Thornton and Pekins 2015). ...
... Bobcats are considered widespread in Oklahoma, and samples included in the current study were collected from a large proportion of the counties (53/77) in Oklahoma. Estimates of bobcat populations in Oklahoma indicate that their numbers have increased since 1981 (Roberts and Crimmins 2010); the abundance of both bobcats and competent tick vectors across Oklahoma probably contributed to the high prevalence of C. felis that we detected. Within Oklahoma, several geographic regions were noted with a higher infection prevalence (central, south-central, northeast, and southeast), whereas in other areas (northwest, southwest), bobcats were less likely to be infected with C. felis. ...
HIGH PREVALENCE OF CYTAUXZOON FELIS IN BOBCATS (LYNX RUFUS) ACROSS OKLAHOMA AND OCCURRENCE IN WEST TEXAS, USA
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Cytauxzoonosis is a fatal tick-borne disease in domestic cats caused by infection with the apicomplexan Cytauxzoon felis. Bobcats are the natural wild-vertebrate reservoirs for C. felis, and infections are typically subclinical and chronic in this species. The present study was done to determine the prevalence and geographic distribution of C. felis infection in wild bobcats from Oklahoma and the occurrence in northwestern Texas. Tongue samples from 360 bobcats were collected from 53 counties in Oklahoma and 13 samples from three counties in Texas. For DNA extracted from each tongue sample, a probe-based droplet digital PCR assay was performed targeting the C. felis mitochondrial gene cytochrome c oxidase subunit III (cox3). Prevalence of C. felis infection was calculated for each county sampled, and data from individual counties were combined according to geographic regions and compared using chi-square tests. Overall prevalence of C. felis in bobcats from Oklahoma was 80.0% (95% confidence interval [CI], 75.6-83.8). The prevalence of infection was >90% for bobcats from central, northeastern, south-central, and southeastern regions of Oklahoma, but <68% for bobcats from northwestern and southwestern regions. Bobcats from central counties in Oklahoma were 25.693 times more likely to be infected with C. felis compared to all other bobcats sampled from the state. Higher prevalence estimates of C. felis in bobcats appeared to be in counties where known tick vectors are most common. Occurrence of C. felis in bobcats from northwestern Texas was 30.8% (95% CI, 12.4%-58.0%) based on 13 samples. Results of this study support the utilization of bobcats as sentinel animals to identify geographic areas with risk of C. felis infection to domestic cats.
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... In 1946 an adult male killed along the Ohio River in Scioto was the first record of a bobcat in Ohio after a century of extirpation (ODNR 2018), and the number of confirmed bobcat sightings has been steadily increasing since (Bobcat Management Plan 2023). Recent evidence indicates that bobcats have successfully recolonized Ohio and are expanding their range (Roberts and Crimmins 2010;ODNR 2018;Prange and Rose 2020;Popescu et al. 2021), prompting the Ohio Department of Natural Resources (ODNR) to remove them from the Ohio Endangered and Threatened Species List. Consequently, there is increased interest from recreational hunters and trappers to open a harvest season for bobcats in Ohio. ...
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The proof is in the poop: First density estimates for a recovering bobcat population in southeast Ohio using DNA from scat
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The recovery of mammalian species in the US Midwest through natural recolonization constitutes a conservation success story, yet management remains challenging due to many unknowns related to population dynamics and abundance. Abundance is a critical parameter for management decisions, and estimating the density and abundance of elusive species, such as terrestrial carnivores, remains challenging despite recent technological advances. In this study, we evaluated density and abundance of a recovering carnivore species, the bobcat (Lynx rufus) in two areas of Ohio using non-invasive DNA from scat. The target areas in eastern and southern Ohio have been shown to have uneven dynamics and recolonization success and we expected that this would be reflected in differences in density and abundance. We collected 298 bobcat scats between July 2018 and April 2019 on 150 km of repeated transects. Of these, 102 scats were successfully genotyped, and 55 individuals were identified (33 in eastern Ohio and 22 in southern Ohio). Using Spatially Explicit Capture-Recapture models, we estimated 17.9 ± 4.3 and 11.3 ± 2.9 bobcats/100 km2 in eastern and southern Ohio study areas, respectively. Our results support prior telemetry data which indicated that bobcats in eastern Ohio had smaller home-ranges than bobcats in southern Ohio, and thus could support a higher density of individuals. The higher densities were similar to other eastern US populations and are much higher than other Midwestern recovering populations. Our results provide a snapshot of the population status and can be used to determine sustainable management strategies for Ohio’s bobcat population
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... The bobcat, L. rufus or Felis rufus is the most widely distributed carnivore in North America (Roberts and Crimmins, 2010) with a tolerance for fragmented habitats (Riley et al., 2004). The majority of studies on T. cati in bobcats are from North America with the exception of one study from Mexico (Table 6). ...
A walk on the wild side: A review of the epidemiology of Toxocara canis and Toxocara cati in wild hosts
Article
Full-text available
  • Nov 2023
Toxocara species are cosmopolitan nematode parasites of companion, domestic and wild hosts. Of the 26 known species of Toxocara, only Toxocara canis and Toxocara cati are definitively zoonotic. The significance of wild carnivores as definitive hosts of T. canis and T. cati respectively, has received far less attention compared to domestic dogs and cats. Complex environmental changes have promoted increasing contact between wildlife, domestic animals and humans that can enhance the risk of pathogen spillover. This review lists a total of 19 species of wild canid host that have been shown to act as definitive hosts for T. canis and a total of 21 species of wild felid host. In general, the number of publications focusing on felid host species is fewer in number, reflecting the general paucity of data on T. cati. The wild canids that have received the most attention in the published literature include the red fox (Vulpes vulpes), the wolf (Canis lupus), and the golden jackal (Canis aureus). The wild felid species that has received the most attention in the published literature is the Eurasian lynx (Lynx lynx). Some non-canid and non-felid hosts also act as definitive hosts of Toxocara species. Certainly, red foxes would appear to be the most significant wild species in terms of their potential to transmit Toxocara to domestic dogs and humans via environmental contamination. This can be explained by their increasing population densities, encroachment into urban areas and their dietary preferences for a wide range of potential paratenic hosts. However, a major challenge remains to assess the relative importance of wild hosts as contributors to envi- ronmental contamination with Toxocara ova. Furthermore, one major constraint to our understanding of the significance of wildlife parasitism is a lack of access to samples, particularly from rare host species.
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... Cytauxzoonosis is a threat to domestic cats that encounter tick vectors. Cases of cytauxzoonosis are increasing (Miller and Davis, 2013), concurrently with the range of the parasite, the vector (Raghavan et al., 2019), and the wild reservoir (Roberts and Crimmins, 2010), which seems to have spread across the contiguous states of the United States. Bobcats and ticks can show a high prevalence of the parasite (Zieman et al., 2017). ...
Clinical and Subclinical Cytauxzoon Felis Infections in Domestic Cats from a Recently Identified Endemic Region
Article
  • Oct 2023
Cytauxzoon felis is a tick-transmitted intraerythrocytic apicomplexan infecting felids in the southeastern and midwestern United States. Bobcats (Lynx rufus) are the natural wildlife reservoir of C. felis, where in enzootic areas prevalence can reach 100%. Domestic cats can be subclinically infected with C. felis or can develop cytauxzoonosis. Two studies have documented the presence of C. felis in domestic cats in Illinois; these studies have shown a limited number of cases submitted to specialty labs. During 2014-2018, we obtained blood samples collected by veterinary staff from 514 cats that were apparently healthy and 74 cats that were suspected of cytauxzoonosis. These samples were screened using a sensitive, nested PCR to detect the presence of C. felis DNA. We herein document frequent occurrences of cytauxzoonosis (8-15 cases/year from 4 veterinary clinics) and 12.5% prevalence of subclinical infections in southern Illinois, a locality showing a sharp increase in cases of cytauxzoonosis. Our results suggest a high risk of cytauxzoonosis in southern Illinois, despite only recently being recognized in the area. We found no specific risk factors for cytauxzoonosis or subclinical infections in this location. In addition, cases of cytauxzoonosis occur every month of the year (with the highest frequency in summer) and therefore tick prevention should be used in domestic cats in enzootic regions throughout the year.
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... Coyotes first arrived to northern Georgia in the 1980s and now have established breeding populations throughout the eastern U.S. [20]. Although current density estimates are lacking, coyote and bobcat numbers are purportedly increasing across most of the southeastern U.S. [6,21]. Black bears were considered rare in parts of the Southern Appalachians until the 1970s due to near extirpation at the beginning of the century [22]. ...
White-tailed deer (Odocoileus virginianus) fawn survival and the influence of landscape characteristics on fawn predation risk in the Southern Appalachian Mountains, USA
Article
Full-text available
In the Southern Appalachian region of the United States, harvest data has indicated the occurrence of low deer densities while exposing a trend of declining white-tailed deer (Odocoileus virginianus) populations over the past several decades in northern Georgia. A triumvirate of increasing fawn predator populations reside in the Southern Appalachian Mountains including coyotes (Canis latrans), black bears (Ursus americanus) and bobcats (Lynx rufus). This region is also characterized by a homogenous landscape composed of mature forests and sparse understory vegetation, likely lacking adequate cover to offer fawns refugia from predators. Our objectives were to estimate survival and cause-specific mortality rates of fawns while assessing a possible link between mortality risk, intrinsic fawn characteristics (i.e., birth mass, Julian birth date, sibling status), and landscape features within fawn usage areas. During 2018-2020, we radio-collared 71 fawns within the Chattahoochee National Forest of northern Georgia, USA and monitored survival to 12 weeks of age. We observed low fawn survival (cumulative = 0.157, 95% CI = 0.091-0.273; vaginal implant transmitter = 0.196, 95% CI = 0.096-0.403) with predation as the leading cause of all known mortalities (45 of 55 mortalities; 82%) due primarily to coyotes (n = 22), black bears (n = 12), and bobcats (n = 7). Relationships between landscape features and fawn predation risk were minimal with only one informative covariate. Increasing amounts of early successional land cover within fawn usage areas decreased fawn mortality risk within the first 20 days of life, but elevated mortality risk thereafter. All fawns with any amount of early successional land cover in their usage areas died of predation (n = 13) at various time intervals, suggesting limited areas of potential fawning cover may be targeted by predators. However, fawn predation risk seemed to be high regardless of landscape covariates due to the limited number of surviving fawns. Coyote-caused mortality occurred over a longer period at a consistently higher magnitude than all other forms of mortality, indicating possible delayed prey-switching behavior and coyote predation as an important factor of fawn survival. The low recruitment of fawns influenced by high predation rates and homogenous habitat conditions is likely the cause of deer population declines in the region.
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... Species that are less plastic are more likely to be disadvantaged in high-disturbance environments, while behavioral flexibility leads to increased success and tolerance of anthropogenic environments (Lowry et al. 2013, Lovell et al. 2022. For example, bobcat populations in North America only recently began recovering after record lows in the 1900's (Roberts and Crimmins 2010), while coyote populations have both increased in number and range across North America with anthropogenic land changes and extirpation of large predators (Linnell andStrand 2000, Laliberte andRipple 2004), illustrating the implications of species-level plasticity and tolerance to human modification. However, while a nuanced response to human modification can provide benefits in exploiting anthropogenic habitat, there are also risks associated with this behavior. ...
Using a novel framework of animal space-use behaviors reveals a gradient of responses to human modification
Preprint
  • Feb 2023
Spatial behavior, including home-ranging behaviors, habitat selection, and movement, can be extremely informative in estimating how animals respond to landscape heterogeneity. Responses in these spatial behaviors to factors such as human modification and resources on the landscape can highlight a species’ spatial strategy to maximize fitness and minimize risk. These strategies can vary on spatial, temporal, and individual scales, and the combination of behaviors on these scales can lead to very different strategies among species. Harnessing the variation present at these scales, we developed a framework for predicting how species may respond to changes in their environments on a gradient ranging from generic, where a species exhibits broad-stroke spatial responses to their environment, to nuanced, in which a species uses a combination of temporal and spatial strategies paired with functional responses in selection behaviors. Using 46 GPS-tracked bobcats and coyotes inhabiting a landscape encompassing a range of human modification, we evaluated where each species falls along the generic-to-nuanced gradient. Bobcats and coyotes studied occupied opposite ends of this gradient, using different strategies in response to human modification in their home ranges, with bobcats broadly expanding their home range with increases in human modification and clearly selecting for or avoiding features on the landscape with temporal consistency. Meanwhile, coyotes did not expand their home ranges with human modification, but instead displayed temporal and spatial adjustments in their functional responses to human modification. These differences in response to habitat, resources, and risk between the two species highlighted the variation in spatial behaviors animals can use to exist in anthropogenic environments influenced by interspecific variation in behavioral plasticity. Categorizing animal spatial behavior based on the generic-to-nuanced gradient can help in predicting how a species will respond to future change based on their current spatial behavior.
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... Bobcats (Lynx rufus) are a felid species distributed across the United States, southern Canada, and Mexico [5,6]. As predators, they play a crucial role in the ecosystems they inhabit, preying upon small mammals and reptiles [7]. ...
A circovirus and cycloviruses identified in feces of bobcats (Lynx rufus) in California
Article
Full-text available
Viruses in the family Circoviridae have small circular single-stranded DNA (ssDNA) genomes. Circoviruses are known to infect a wide variety of animals, with notable disease pathology in psittacine (psittacine beak and feather disease) and porcine (postweaning multisystemic wasting syndrome) species. There is still a dearth of research investigating circoviruses associated with felid species. In six fecal samples collected from bobcats (Lynx rufus) in California from 2010 to 2011, we identified six viruses belonging to the genera Circovirus (n = 1) and Cyclovirus (n = 5), using a high-throughput-sequencing-based approach. Of these, the virus in the genus Circovirus represents a new species, as it shares only 54-60% genome-wide sequence identity with the other members of this genus. The five viruses in the genus Cyclovirus represent three new species, sharing <73% genome-wide sequence identity with all other cycloviruses. Three of the cycloviruses belong to a single putative species and were obtained from the feces of three individual bobcats, sharing 95.7-99.9% sequence identity, whereas the other two unique cycloviruses were identified in a single fecal sample. At present, it is unknown whether the identified viruses infect bobcats, their prey, or their gut parasites.
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Population Dynamics of a Declining White-Tailed Deer Population in the Southern Appalachian Region of the United States
Article
Full-text available
  • Nov 2023
Although generally abundant, white-tailed deer (Odocoileus virginianus) populations in the southeastern United States have recently experienced several localized declines attributed to reduced fawn recruitment following the establishment of coyotes (Canis latrans). The Southern Appalachians is a mountainous region suggested to be experiencing white-tailed deer declines, as harvest numbers and hunter success rates have substantially decreased in northern Georgia since 1979. Low fawn survival (16%) was also recently documented in the Chattahoochee National Forest (CNF) in northern Georgia, necessitating further examination. We radio-collared 14 yearling and 45 adult female white-tailed deer along with 71 fawns during 2018–2020 in the CNF to estimate field-based vital rates (i.e., survival and fecundity) and parameterize stage-structured population models. We projected population growth rates (λ) over 10 years to evaluate the current rate of decline and various other management scenarios. Our results indicated that the observed population would decline by an average of 4.0% annually (λ = 0.960) under current conditions. Only scenarios including antlerless harvest restrictions in addition to improved fawn survival resulted in positive growth (λ = 1.019, 1.085), suggesting these measures are likely necessary for population recovery in the region. This approach can be applied by wildlife managers to inform site-specific management strategies.
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Mesocarnivores of Western Rangelands
Chapter
Full-text available
  • Sep 2023
There are 22 species of mesocarnivores (carnivores weighing < 15 kg) belonging to five families that live in rangelands of the western United States. Mesocarnivores are understudied relative to large carnivores but can have significant impacts on ecosystems and human dimensions. In this chapter, we review the current state of knowledge about the biology, ecology, and human interactions of the mesocarnivores that occupy the rangelands of the central and western United States. In these two regions, mesocarnivores may serve as the apex predator in areas where large carnivores no longer occur, and can have profound impacts on endemic prey, disease ecology, and livestock production. Some mesocarnivore species are valued because they are harvested for food and fur, while others are considered nuisance species because they can have negative impacts on ranching. Many mesocarnivores have flexible life history strategies that make them well-suited for future population growth or range expansion as western landscapes change due to rapid human population growth, landscape development, and alterations to ecosystems from climate change; however other mesocarnivores continue to decline. More research on this important guild is needed to understand their role in western working landscapes.
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Simulated effects of roadkill and harvest on the viability of a recovering bobcat population
Article
Full-text available
  • Jul 2023
Bobcats ( Lynx rufus ) were extirpated from many midwestern states in the mid‐1800s owing to habitat loss and overharvesting. Recently, bobcats have recolonized Ohio, USA, and neighboring states and given their furbearer status elsewhere, there is interest in opening a harvest season; however, demographic factors and viability of this population are currently unknown. We developed a spatial population simulation model to assess the long‐term viability of the bobcat population in Ohio in the face of 2 human‐induced factors limiting population growth: potential harvest and road mortality. We combined habitat suitability and road mortality risk data with vital rates for bobcats from Ohio and other populations to simulate possible scenarios for Ohio's population. Our baseline scenario simulations showed no risk of extinction for Ohio's bobcat population in the next 40 years, but population trajectories were lower and exhibited greater uncertainty when we modeled the population with a lower maximum density of animals per cell. At low harvest intensity ( αh = 0.05), the bobcat population also exhibits low risk of extinction. When harvest intensity increases ( αh = 0.1, 0.15) or when adults (≥2 yr) are targeted by harvest, simulations show declining populations, greater uncertainty in projections, and possible risk of extirpation. Our models indicated that if harvest and road mortality are additive, then the bobcat population could withstand marginal increases in road mortality ( αr = 0.1) at low harvest intensity ( αh = 0.05). Future increases in road mortality with higher harvest intensity ( αh = 0.1, 0.15) were unsustainable. Our results can be used by wildlife managers to assist with decisions on population‐level management. This simulation model can easily be adapted for other large mammals and can be modified to assess a variety of ecological and anthropogenic influences to wildlife populations.
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Mortality of Pronghorn Antelope Fawns in Western Utah
Article
  • Jul 1973
Over a period of 5 years 117 pronghorn antelope (Antilocapra americana) fawns 1-5 days of age were captured in a 4,000-hectare enclosure and fitted with radio transmitters to provide a means of relocating them to determine causes of mortality. Each fawn was located and observed daily until approximately 4 months of age or until death. Fawns with transmitters that functioned beyond this period were thereafter checked periodically. A total of 55 cases of fawn mortality were discovered during the study. Bobcats (Lynx rufus) accounted for 27 deaths; golden eagles (Aquila chrysaetos) one; and coyotes (Canis latrans) one. Two died from salmonellosis, three from pneumonia, four from starvation, and one from an esophageal injury. Five died from unknown causes and eleven were abandoned by does as a result of handling. The ages of fawns definitely killed by bobcats ranged from 3 to 104 days; one weighed 22 kg at the time of kill.
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The Limiting Effects of Natural Predation on Experimental Cotton Rat Populations
Article
  • Oct 1968
Survival curves for 2- to 6-month periods were plotted for 17 different populations of nonbreeding cotton rats (Sigmodon hispidus) introduced into isolated or enclosed areas of natural habitat. Eight populations were introduced onto predator-free islands or into a 1-acre, predator-proofed enclosure of old field habitat, and nine populations were released into 1-acre enclosures freely accessible to bird and mammal predators. Radioactive pins (cobalt-60 or zinc-65) inserted under the skin aided in determining the fate of cotton rats which failed to appear in live traps. Survival curves were linear or convex for introduced populations protected from predation and strongly concave for those open to natural predators. Abundant evidence for kills by hawks, foxes, and bobcats was found in the latter cases. A density of about 15/acre, the mean point of inflection in the survival curves, was considered to be a "predator-limited carrying capacity" since mortality was high above, and low below, this density when predators were active. The experimental study has special relevance to the fall and winter cotton rat populations in the southeastern United States. It is concluded that when diverse and highly mobile predator populations are present they are more important than food, social interaction, or weather in regulating cotton rat density.
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Statewide modeling of bobcat, Lynx rufus, habitat in Illinois, USA
Article
We used sighting location and remotely sensed habitat data, multivariate statistical techniques, and a geographic information system to model bobcat (Lynx rufus) habitat in Illinois, thereby providing state wildlife managers with information to review the listing of bobcats as a state-threatened species and contribute to the development of a statewide management plan. We used canonical discriminant function analysis to model presence/absence and relative abundance of bobcats statewide. These models suggested that bobcats occurred in moderate to high abundance in 23 of 98 counties statewide (23%). We used stepwise logistic regression (SLR) analysis to model statewide habitat suitability. Spatial modeling of the SLR equation predicted that 29% of Illinois contained suitable habitat classified as P>0.50. Models were accurate when validated with an independent data set and indicated the importance of woods-related habitat variables to bobcats. In conclusion, these models provided tools to rapidly assess status that contributed to delisting bobcats as a threatened species in Illinois and provided further information to guide conservation efforts.
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The legal status of wildcats in the United States
  • Jan 1971
  • C E Faulkner
Faulkner CE. 1971. The legal status of wildcats in the United States. Pages 124-125 in Jorgensen RM, Mech LD, editors. Proceedings of a Symposium on the Native Cats of North America, Their Status and Management. 36th American Wildlife and Natural Resources Conference. Twin Cities, Minnesota: U.S. Fish and Wildlife Service. Available from the corresponding author.
Ecology of bobcats relative to exploitation and a prey decline in southeastern Idaho
  • Jan 1990
  • WILDLIFE MONOGR
  • S Knick
Knick S. 1990. Ecology of bobcats relative to exploitation and a prey decline in southeastern Idaho. Wildlife Monographs 108.
A critical review and annotated bibliography of literature on the bobcat
  • Jan 1987
  • E M Anderson
Anderson EM. 1987. A critical review and annotated bibliography of literature on the bobcat. Colorado Division of Wildlife Special Report 62. Available from the corresponding author.
Summary of the symposium on the native cats of North America Pages 2–8 in
  • Jan 1971
  • Im Cowan
Cowan IM. 1971. Summary of the symposium on the native cats of North America. Pages 2–8 in Jorgensen RM, Mech LD, editors. Proceedings of a Symposium on the Native Cats of North America, Their Status and Management. 36th American Wildlife and Natural Resources Conference. Twin Cities, Minnesota: U.S. Fish and Wildlife Service. Available from the corresponding author.
Proposal to remove the bobcat from Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora
  • Jan 1982
  • 1242-1246
  • U S Fish
  • Wildlife Service
U.S. Fish and Wildlife Service. 1982. Proposal to remove the bobcat from Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora. Federal Register 47(6):1242-1246.