2008 SOUTHEASTERN NATURALIST 7(1):111–124
Scale-dependent Habitat Selection by Female Florida
Black Bears in Ocala National Forest, Florida
Melissa A. Moyer1, J. Walter McCown2, and Madan K. Oli1,*
Abstract - Habitat selection infl uences many aspects of a species’ ecology, and can
have substantial management implications. We studied habitat selection by female
Ursus americanus fl oridanus (Florida black bears), a threatened species in Florida,
at two different scales: selection of home ranges within the population range and
selection of habitat types within home ranges. At the scale of home range selection
within the population range, bears showed preference for xeric habitats (xeric oak
scrub and Pinus clausa [sand pine] forest) during summer; there was no evidence of
habitat selection during fall. At the scale of habitat selection within the home range,
bears showed preference for mesic (pine fl atwood and swamp forest) and preference
against xeric (xeric oak scrub and sand pine forests) habitats; again, there was
no evidence of habitat selection during fall. Contrary to expectations, bears did not
show preference for habitats that contained hard mast-producing plants. This was
at least in part because habitats rich in mast producing plants composed 68% of the
total habitat area. Strategies for management of Florida black bears should encourage
management practices that enhance quality and diversity of mast- and berry-producing
plants.
Introduction
Understanding why animals occur where they do is a cornerstone of ecology
(Krebs 1978). Animals do not use all of the available landscape within
their geographic range, nor do they use different features of the landscape
with equal intensity. Species-habitat associations are the product of both evolutionary
and ecological processes. However, distribution of animals within
their geographic range is often infl uenced by an individual’s habitat selection
(Krebs 1978, Morrison et al. 1992). It is presumed that habitat quality
infl uences fitness, and that animals will choose high-quality habitat over lowquality
habitat when available (Manly et al. 1993).
Selection behaviors often occur across multiple scales and result in a hierarchical
nature of habitat selection (Johnson 1980, Orians and Wittenberger
1991). An individual will select a home range from the population range, and
will also select patches of habitat to use within that home range. Different habitat
attributes may be selected for at different spatial scales. Rettie and Messier
(2000) suggest that the most limiting factors affecting individual fitness should
be selected for at the coarsest scales. Finer-scale habitat selection, therefore,
is based on less-critical factors. Evaluation of habitat selection without
1Department of Wildlife Ecology and Conservation, 110 Newins-Ziegler Hall, University
of Florida, Gainesville, FL 32611. 2Florida Fish and Wildlife Conservation
Commission, 4005 South Main Street, Gainesville, FL 32601. *Corresponding author
- olim@ufl .edu.
112 Southeastern Naturalist Vol.7, No. 1
considering hierarchical effects could lead to inadequate or misleading conclusions
regarding the species’ habitat requirements (Orians and Wittenberger
1991). A simple example is proposed by Conner et al (2003) where an avoided
habitat completely surrounded by a preferred habitat will appear to be used at
a broad scale, but will be interpreted as avoided at a narrower scale. Thus, formal
testing of habitat and resource selection at multiple scales is essential for a
complete understanding of the relationship between animals and their environments
(Aebischer et al. 1993, Alldredge and Ratti 1992, Johnson 1980, Manly
et al. 1993, Morrison et al. 1992). In this study, we considered habitat selection
of Ursus americanus fl oridanus Merriam (Florida black bear), a subspecies
of Ursus americanus Pallas (American black bear), at two spatial scales. The
Florida black bear is listed by the state of Florida as a threatened species. It is
currently restricted to 17% of its former range in Florida due to habitat loss and
fragmentation (Wooding 1993).
The American black bear historically occupied a wide variety of forested
habitats throughout the United States and Canada (Hall 1981). Although their
geographic range has contracted, black bears have retained their affinity to
forested areas. As omnivores, though, they use many different habitat types
(Maehr 1984, Schoen 1990, Smith and Pelton 1990, Wooding and Hardisky
1994). The black bear also is considered to be a landscape species in that
it utilizes a large home range and many different habitats within that home
range (Schoen 1990). These habitats must contain all the requirements for
the bears’ survival and reproduction, including habitat types with adequate
food resources and cover for concealment (Pelton 1986).
Black bear habitat selection has been studied extensively throughout
their geographic range. Previous studies have found that black bears use
habitat types disproportionately to availability, indicating preferences for
some habitat types (Hellgren et al. 1991, Heyden and Meslow 1999, Hirsch
et al. 1999, Jonkel and Cowan 1971, Lindzey and Meslow 1977, Unsworth
et al. 1989, Wooding and Hardisky 1994). Preferred habitat, however, varies
widely depending on geographic region, diversity of available habitats, and
seasonality due to vegetation structure and plant phenology (Fecske et al.
2002, Rogers 1987, Samson and Huot 1998, Stratman et al. 2001).
Conservation of remaining black bears in Florida requires knowledge of
this subspecies’ habitat use at multiple spatial scales and how selection changes
between seasons. Although habitat selection by other subspecies of the American
black bear has been thoroughly investigated, little is known about habitat
selection of Florida black bears. Near the southern tip of their geographic range,
Florida black bears have access to different habitat types and persist in isolated
populations within a human-dominated landscape (Dixon et al. 2006, 2007)
Our objective was to investigate habitat selection by female Florida black
bears in Ocala National Forest in north-central Florida. We tested the null
hypothesis that female black bears did not show habitat preference when
selecting a home range within the population range of Ocala National Forest
and when utilizing habitat types within that home range.
2008 M.A. Moyer, J.W. McCown, and M.K. Oli 113
Field-site Description
We conducted our study in the Ocala National Forest (ONF) in northcentral
Florida, which is located along a ridge of sand dunes and is bisected
by a multi-lane paved road (State Road 40). The forest sloped downward
toward the St. John’s River to the east and the Ocklawaha River to the
west. The lower elevations closer to the rivers corresponded to increasing
mesic forests. Human disturbance, due to selective-logging, clear-cutting,
prescribed-burning, and road-building practices within the forest, provided
much of the heterogeneity in forest-cover type and stand age.
We defined 7 habitat types within the study area based on the forest-cover
types presented in the Florida Vegetation and Land Cover map (FVLC; Table
1, Florida Fish and Wildlife Conservation Commission 2003). We refined
the original FVLC map by merging similar cover types. We did not include
two forest-cover types, present in discrete patches at the periphery of the
study area and contributing less than 2% of the total area, because these were
potentially only available to a few individuals. The 7 remaining habitat types
were Pinus clausa Chapman ex Engelm. Vasey ex Sarg. (sand pine) forest,
xeric Quercus spp. (oak) scrub, Pinus spp. (pine) fl atwoods, swamp forests,
marshes/open water, disturbed areas, and high-impact urban areas.
The most prominent forest-cover type within ONF was sand pine forest
(Fig. 1). The overstory of this cover type was predominantly sand pine,
while the shrub layer consists of six species in approximately the following
order of abundance: Quercus myrtifolia Willd. (myrtle oak) or Q. inopina
Ashe (scrub oak), Serenoa repens (Bartr.) Small (saw palmetto), Q. geminata
Small (sand live oak), Q. chapmanii Sarg. (Chapman’s oak), Lyonia ferruginea
(Walt.) Nutt. (rusty lyonia), and Ceratiola ericoides Michx. (Florida
rosemary) (Myers and Ewel 1990). Density of sand pine in the overstory
can vary greatly from dense stands to widely scattered trees and is inversely
related to density of the scrub oak, the predominant understory species. The
xeric oak scrub was similar to sand pine forest, though it lacked the overstory
Table 1. Percent composition of habitat types in the Ocala National Forest (ONF), FL. Seven
habitat types were defined within the study area from the original forest-cover types identified
in the Florida Vegetation and Land Cover Map (FVLC; Florida Fish and Wildlife Conservation
Commission 2003). Original FVLC cover types corresponding to each of our habitat types also
are given.
Habitat type % Composition Original FVLC cover types
Xeric oak scrub 23.9 Xeric oak scrub
Sand pine forest 44.3 Sand pine scrub
Pine fl atwoods 3.2 Pinelands
Marsh/open water 7.0 Fresh water marsh and wet prairie, sawgrass
marsh, cattail marsh, open water
Swamp forest 8.6 Shrub swamp, bay swamp, cypress swamp,
mixed wetland forest, hardwood swamp
Disturbed 10.0 Shrub and brushland, grassland, bare soil/
clearcut, agriculture, low-impact urban
High-impact urban 1.4 High-impact urban, mining (extractive)
114 Southeastern Naturalist Vol.7, No. 1
of sand pine and constituted the second largest portion of the study area.
This forest was intensively managed for timber and stands of 50–100 ha
were regularly clearcut. We classified these as recent clearcuts (less than 5
years old) and other open, disturbed areas such as roadsides and forest logging
roads as disturbed. These three cover types (disturbed, xeric oak scrub,
and sand pine scrub), represented three successional stages within ONF, and
their distribution created a mosaic of stand ages.
The remaining land-cover types were found more frequently at lower elevations
and were mesic or hydric in nature. Pine fl atwoods had an overstory
composed of Pinus elliottii Engelm. (slash pine) or P. serotina Michx. (pond
pine), while saw palmetto, Ilex glabra (L.) Gray (gallberry), and Lyonia
lucida (Lam.) K. Koch (fetterbush) were frequent understory species. We
merged the FVLC land-cover types, hardwood swamp, bay swamp, cypress
swamp and mixed wetland forest, to define our category swamp forests.
Swamp forests had standing water or saturated soils for at least part of the
year and a hardwood component (Ewel 1990). Major tree species included
Taxodium distichum (L.) L.C. Rich (cypress), Sabal palmetto (Walt.) Lodd.
ex J.A. & J.H. Schultes (sabal palmetto), Gordonia lasianthus (L.) Ellis
(loblolly bay), and Magnolia grandifl ora L. (sweet bay).
We combined open water and freshwater marshes into a single habitat type
because of the tendency for one to grade into the other with variation in annual
and seasonal rainfall. High-impact urban areas included major paved roads
(e.g., State Road 40) and developed areas. Although the proportion of this cover
type within the study area was low, it was readily available to most bears.
Figure 1. Map of habitat types in Ocala National Forest in north-central Florida. Forestcover
types of the Florida Vegetation and Land Cover Map (FWC 2003) were merged
to form seven habitat types in the ONF study area (represented by the thick black polygon).
State road 40 (SR 40) bisects the study area and state road 19 (SR 19) is near the
eastern edge. Much of the swamp forest in the center of ONF is associated with Juniper
Springs, which fl ows toward Lake George shown in the upper right corner.
2008 M.A. Moyer, J.W. McCown, and M.K. Oli 115
Methods
Field methods
We captured black bears from 1999 through 2002 using spring-activated
Aldrich foot snares (Aldrich Snare Co., Clallam Bay, WA) disguised
in natural vegetation and baited with donuts or a combination of corn and
donuts. Although we trapped bears from May through December, the most
intensive trapping occurred during summer months. We anesthetized bears
with Telazol® delivered through a CO2-charged, low-impact dart delivery
system. Once sedated, bears were ear-tagged and lip-tattooed for individual
identification. We collected hair and blood samples for genetic analyses, and
we extracted a pre-molar tooth to estimate age (Willey 1974). We recorded
morphometric measurements, body mass (kg), and physical and reproductive
condition. We fitted female bears with a motion-sensitive radiocollar
(150–151 MHz; Telonics®, Mesa, AR). Radiocollars included a leather connector,
which would allow the collar to fall off within two to three years. We
considered reproductive females or those ≥3 years of age as adults, and these
were included in analyses (Garrison et al. 2007).
We located adult female bears 1–3 times per week during 2000–2003.
We obtained most of the locations from the ground during daylight hours
(0900–1800) using a 4-element hand-held antenna and a Telonics® receiver,
but we also tracked bears 1–4 times per month from a fixed-wing aircraft.
We did not locate bears on any two consecutive days to avoid autocorrelations,
and we spread our sampling effort evenly across the sampling period.
For each bear, we obtained ≥3 compass bearings within 30 minutes. We
estimated point locations from ground telemetry using the program Locate
II (Pacer 1990). We estimated telemetry error by comparing estimated locations
of test collars, dropped collars, and natal dens of female bears to their
actual locations.
Data analysis
We used radiolocations of all female bears over the duration of our
study to define the 620-km2 ONF study area (Fig. 1) by using the composite
minimum convex polygon (MCP) of these bear locations, excluding distant
outliers. For each bear, we used the program CALHOME (Kie et al. 1994)
to estimate the 95% MCP for three categories of home ranges: a) overall
home ranges, b) summer home ranges, and c) fall home ranges. To have a
home range included, each bear needed at least 30 locations over the given
time period. Data were pooled over years to increase the number of bears
and locations that could be included in the analysis. Our goal was to assess
habitat associations across a broad temporal scale, although we recognize
that annual variations may have been missed.
We estimated overall (or multi-annual) home ranges for each bear from
locations collected during May–December over the four years of the study.
Bears denned from January–April; thus, we did not include locations during
these months. We estimated summer home ranges for each bear from
116 Southeastern Naturalist Vol.7, No. 1
locations collected between May and August combined over the four years
of the study. May was selected as the beginning of the study period because
this was the first month after all bears emerged from their dens. We estimated
fall home ranges for each bear from locations collected between September
and December during the course of the study. September was chosen as the
transition between summer and fall based on the start of the availability of
acorns at this time and to equalize sampling effort across seasons. We used
estimates of home ranges based on MCP method so that all intervening habitat
among telemetry locations would be included in the home range and thus
considered available.
We used a distance-based method to identify habitat preferences within
ONF (Conner and Plowman 2001, Conner et al. 2003). This method compares
actual distances from radio-telemetry locations to each habitat type
to expected distances to each habitat type to test the null hypothesis of
no selection (Conner et al. 2003). Locations closer to a given habitat type
than expected indicate preference of that habitat type. When compared to a
classification-based method (e.g., compositional analysis; Aebischer et al.
1993), inferences based on the distance-based analysis are more robust with
respect to habitat misclassifications (Bingham and Brennan 2004, Conner et
al. 2003).
The coarse-scale of habitat selection analysis was selection of the home
range from the population range (2nd-order selection of Johnson [1980]). To
evaluate habitat selection at this level, we generated random points with a
uniform distribution at the density of 300 points per km2 using the Animal
Movement extension of ArcView 3.2 (ESRI, Redlands, CA; Hooge et al.
1999). We selected this density of points because it was where the variance
of the average distance to each habitat type began to stabilize, indicating that
it adequately represented the habitat types present (Fig. 2). Habitat availability
was represented using random points within the study area. Habitat
use was represented using random points within each bear’s home range. We
measured the distance from each random point to the nearest patch of each
habitat type. Our null hypothesis was that mean distance to each habitat did
not differ between the study area and the home range. Rejection of the null
hypothesis of no habitat selection (p < 0.05) indicated that bears had preference
for at least one habitat.
If the null hypothesis was rejected, we used a paired t-test to determine
which habitat types were preferred and which were avoided. We
ranked the habitat types in order of preference and determined significant
differences between habitat types using a paired t-test. These analyses
were performed using the SAS code (SAS Inc 1999) adapted from Conner
and Plowman (2001).
We also evaluated habitat selection within the individual home range
(3rd-order selection of Johnson [1980]). In this case, habitat availability was
defined using random points within each home range, while habitat selection
was defined by the radio-telemetry locations for each bear within the home
2008 M.A. Moyer, J.W. McCown, and M.K. Oli 117
range. We performed statistical tests as described above. Again, each habitat
type was evaluated independently, and a matrix of rankings was generated if
the null hypothesis of no habitat selection was rejected.
Figure 2. The relationship between density of random points per km2 and variance
of the mean distance to individual habitat types. Curves for the remaining 5 habitat
types are similar to those for the swamp forest (top) and xeric oaks scrub (bottom)
presented here.
118 Southeastern Naturalist Vol.7, No. 1
Results
The mean number of locations (± SE) used to estimate each home range
was 83 ± 11 locations from 22 bears for overall, 61 ± 6 locations from 20
bears for summer, and 56 ± 6 locations and 19 bears for fall. The mean homerange
size was 25.74 ± 7.99 km2 for overall home ranges, 11.09 ± 2.48 km2
for summer home ranges, and 35.17 ± 11.14 km2 for fall home ranges. The
mean ground radio-telemetry error was 152.6 m (n = 312, SD = 180.1), and
the mean aerial radio-telemetry error was 251 m (n = 25, SD = 270.3).
At the scale of home-range selection within the landscape, no habitat
preference was found for the overall or the fall home ranges, indicating that
habitat selection did not occur at these spatial and temporal scales (Table 2).
However, habitat selection did occur as bears selected a summer home range
(p = 0.026). In particular, mean distances to xeric oak scrub and sand pine
forest were significantly less than expected (p < 0.001, and p = 0.014, respectively).
Mean distances to all other habitat types were as expected. The
order of preference was: xeric oak scrub > sand pine forest > disturbed > pine
fl atwoods > swamp forest > marsh/open water > high-impact urban. Pairwise
comparisons suggested that xeric oak scrub was preferred over disturbed,
pine fl atwoods, and high-impact urban patches (Table 3).
Analysis of habitat selection within the home range indicated that mean
distances to habitat types were similar and habitat selection did not occur
(Table 2). During summer, however, habitat selection was detected (p =
0.026). For summer home ranges, individual comparisons indicated that
bears were located significantly farther away from xeric oak scrub than
the random points within the home range (p = 0.005). The order of habitat
preference at this scale was: high-impact urban > pine fl atwoods > swamp
forest > marsh/open water > disturbed > xeric oak scrub > sand pine forest.
Radio-telemetry locations were significantly closer to high-impact urban and
pine fl atwoods than to xeric oak scrub and disturbed cover types (Table 4).
Table 2. Results of the multivariate analysis of variance testing for habitat selection by female
Florida black bears based on distance-based method (Conner and Plowman 2001) in Ocala
National Forest, FL. Results of analyses at two spatial scales are shown: selection of the home
range from the landscape (home-range selection) and selection of habitat types within the
home range (habitat selection within the home range) for overall (multi-annual), summer, and
fall home ranges. The F value and significance level (p) are given for each analysis. A significant
p value (p < 0.5) indicates that bears exhibited habitat selection. N represents the number
of home ranges included in each analysis.
Test N df F p
Home-range selection
Overall 22 7,15 0.90 0.530
Summer 20 7,13 3.46 0.026
Fall 19 7,12 0.70 0.674
Habitat selection within the home range
Overall 22 7,15 1.60 0.210
Summer 20 7,12 3.46 0.026
Fall 19 7,12 1.85 0.166
2008 M.A. Moyer, J.W. McCown, and M.K. Oli 119
Table 3. Ranking matrix of habitat types used by female black bears when selecting a home range in Ocala National Forest during summer (May–August). The
habitat types are listed in order of preference, and t statistics (p-value) are given for each pair of habitat types. A negative t-statistic indicates that the column
cover type was preferred to the row cover type.
Cover type Xeric oak scrub Sand pine forest Disturbed Pine fl atwoods Swamp forest Marsh/open water High-impact urban
Xeric oak scrub 0.05 (0.961) 3.89 (0.001) 3.10 (0.006) 1.66 (0.114) 2.07 (0.053) 2.65 (0.016)
Sand pine forest -0.05 (0.961) 1.57 (0.132) 1.86 (0.078) 1.30 (0.208) 1.66 (0.113) 2.66 (0.015)
Disturbed -3.89 (0.001) -1.57 (0.132) 0.78 (0.443) 0.49 (0.632) 0.85 (0.406) 1.41 (0.175)
Pine fl atwoods -3.10 (0.006) -1.86 (0.078) -0.78 (0.443) 0.15 (0.880) 0.65 (0.523) 1.10 (0.287)
Swamp forest -1.66 (0.114) -1.30 (0.208) -0.49 (0.632) -0.15 (0.880) 0.75 (0.463) 0.89 (0.386)
Marsh/open water -2.07 (0.053) -1.66 (0.113) -0.85 (0.406) -0.65 (0.523) -0.75 (0.463) 0.41 (0.683)
High-impact urban -2.65 (0.016) -2.66 (0.015) -1.41 (0.175) -1.10 (0.287) -0.89 (0.386) -0.41 (0.683)
Table 4. Ranking matrix of habitat types used by female black bears when selecting habitat within a home range in Ocala National Forest during summer
(May–August). The habitat types are listed in order of preference and t statistics (p-value) are given for each pair of habitat types. A negative t statistic indicates
that the column cover type was preferred to the row cover type.
Cover type High-impact urban Pine fl atwoods Swamp forests Marsh/open water Disturbed Xeric oak scrub Sand pine forest
High-impact urban 1.10 (0.286) 1.06 (0.301) 1.16 (0.260) 2.86 (0.010) 2.62 (0.017) 1.16 (0.259)
Pine fl atwoods -1.10 (0.286) 0.38 (0.708) 0.57 (0.576) 2.97 (0.008) 2.76 (0.012) 1.04 (0.310)
Swamp forests -1.06 (0.301) -0.38 (0.708) 0.22 (0.825) 2.06 (0.053) 1.97 (0.063) 0.98 (0.342)
Marsh/open water -1.16 (0.260) -0.57 (0.576) -0.22 (0.825) 2.03 (0.056) 2.14 (0.046) 0.97 (0.346)
Disturbed -2.86 (0.010) -2.97 (0.008) -2.06 (0.053) -2.03 (0.056) 0.68 (0.504) 0.70 (0.493)
Xeric oak scrub -2.62 (0.017) -2.76 (0.012) -1.97 (0.063) -2.14 (0.046) -0.68 (0.504) 0.64 (0.533)
Sand pine forest -1.16 (0.259) -1.04 (0.310) -0.98 (0.342) -0.97 (0.346) -0.70 (0.493) -0.64 (0.533)
120 Southeastern Naturalist Vol.7, No. 1
Discussion
There was no evidence to suggest that Florida black bears selectively
used habitat types when selecting overall and fall home ranges, or when
using habitats within those home ranges. However, during the summer,
the null hypothesis of no habitat selection was rejected for 2nd- and 3rd-order
selection.
For 2nd-order selection, summer home ranges included more xeric oak
scrub and sand pine forest than expected, while other habitat types were
included in expected proportions. These scrub oak habitats frequently have
a very dense understory, which provides excellent escape cover. Given the
importance of hard mast for black bears during fall (Maehr and Brady 1984,
Roof 1997), we expected a preference for habitat types containing hard-mast
producing plants in that season. Contrary to this expectation, however, we
found no evidence of habitat selection during fall or when data for fall and
spring were pooled. Although black bears did not select home ranges to
include proportionately more acorn-producing habitat types than available,
this finding requires careful interpretation. Sand pine forest and xeric oak
scrub combined comprised ca. 68% of available habitat in the study area
(Table 1), and were thus heavily used.
While sand pine forest and xeric oak scrub were the most preferred
habitats for summer home ranges at the coarse scale of analysis, these same
habitats were the least preferred within the home range. Within summer
home ranges, black bears were more closely associated with pine fl atwoods
and swamp forests than expected. The scrub habitats may have been least
preferred during summer because they primarily produce hard mast available
during fall. Pine fl atwoods and swamp forests have a higher vegetation
diversity, abundant berry producing species, and saw palmetto shoots which
are the largest components in the summer diet (Roof 1997). Surprisingly,
high-impact urban habitat was the most preferred habitat type during summer,
but this may be due to the proximity of paved roads to pine fl atwoods
and swamp forest (Fig. 2). Within the study area, these two habitat types are
most abundant near SR 40 and Juniper Springs and south of SR 40 along
SR 19. Areas near roads also may have contained edge habitat that provided
more food. Regardless of the ultimate cause for habitat use near paved roads,
it is important to note that black bears did not avoid roads at this scale of
selection.
No habitat selection was detected within the home range for fall or overall
home ranges. When contrasted with habitat preference within summer
home ranges, bears were often found closer to sand pine forest and xeric
oak scrub during fall and on an annual basis. During fall, the primary food
sources are the acorns of various scrub oak species (Roof 1997). However,
while scrub oaks may provide the most abundant fall food source, selection
of other habitat types and alternative food sources also was observed. Habitat
selection also was not detected for overall home ranges, suggesting that
on a year-round basis there was no preference for habitat type.
2008 M.A. Moyer, J.W. McCown, and M.K. Oli 121
Results of this study suggest parallels between habitat use in ONF and
in other black bear populations, although the unique habitat composition
of ONF makes direct comparison difficult. Other bear populations in the
southeastern United States use riparian and wetland habitats for both food
and cover (Hellgren et al. 1991, Maehr and Wooding 1992, Wooding and
Hardisky 1994), especially upon den emergence because wetlands provide
one of the first available sources of food (Fecske et al. 2002). Other studies
also have confirmed that black bears rely heavily on acorns in hardwood
stands during fall (Garshelis and Pelton 1981, Powell et al. 1997, Smith and
Pelton 1990). Study areas that have a conifer component to the landscape
often report avoidance of this cover type because of a lack of food (Stratman
et al. 2001), although in some cases, conifer forests can be utilized as escape
cover (Fecske et al. 2002).
The use of more mesic cover types during summer in ONF, especially the
swamp forests, refl ects what has been found in other black bear populations.
However, ONF is different from most of the southeastern forests in that hardwood
forests dominated by Quercus rubra L. (red oak) and Quercus alba L.
(white oak) are not common. Instead, abundant fall mast is available in the
sand pine forest and xeric oak scrub from the scrub oak species, especially
myrtle oak and scrub oak. Although sand pine forest and xeric oak scrub are
not considered preferred habitat types, mast of these species is used as a fall
food source (Maehr and Brady 1984, Roof 1997).
Responses to the human-modified habitat types (disturbed and high-impact
urban areas) were mixed. Random points within the home range were
closer to sand pine and xeric oak scrub than to both disturbed and urban
features of the landscape, indicating that when selecting a home range, bears
appear to avoid both paved roads and disturbed areas. At the finer scale,
however, disturbed habitat was still one of the least-preferred habitat types,
but bears selected high-impact urban habitat. Female bears most likely selected
against disturbed areas within their home ranges because they do not
provide necessary cover. Bears do appear to be somewhat tolerant to human
disturbance as long as they have adequate escape cover such as the dense
roadside vegetation of ONF.
Habitat selection in this study for summer home ranges of female bears
was different at different spatial scales. Rettie and Messier (2000) suggest
that the most important, or most limiting, factors affecting individual fitness
should be selected for at the coarsest scales. At the coarse scale, other studies
have found that habitats were selected for predator avoidance in Rangifer
tarandus caribou Gmelin (woodland caribou; Rettie and Messier 2000),
den-site availability in Canis lupus L. (gray wolf; McLoughlin et al. 2004),
and prey availability in barren-ground Ursus arctos Linnaeus (grizzly bears;
McLoughlin et al. 2002), while habitat types with higher food availability
were selected at the finer scale in each of these cases. It has been suggested
that black bears in Washington selected home ranges from the study area to
include sufficient food; however, they used habitat types within the home
122 Southeastern Naturalist Vol.7, No. 1
range for both food and escape cover (Lyons et al. 2003). In our study, the
primary differences between habitat selection of black bears at two spatial
scales during summer were that at the coarser scale, densely forested habitat
types were primarily selected for while human-impacted habitat types were
generally avoided, and that this order was reversed within the home range.
Strongest selection for forested habitat types used for food and cover may
indicate that these factors are most limiting. Specific food resources may be
less limiting and so only selected for at a finer scale.
In ONF, a primary goal of habitat managers should be to maintain a diversity
of habitats. This is critically important as bears use food resources
from different habitats on both a seasonal and annual basis. Reduced diversity
may increase the likelihood that mast failure of one species will have a
dire impact on the population as a whole. At the scale of a stand within the
forest, female bears selected against open disturbed areas. However, these
areas may regenerate to xeric oak scrub over time, which provides both
food and cover. A balance of stand ages should be maintained so that overall
abundance of acorn-producing species in the forest will remain high.
Acknowledgments
We gratefully acknowledge Florida Fish and Wildlife Conservation Commission
(FWC) for funding and logistical support. Additional support was provided by the
Florida Department of Transportation, US Forest Service, Wildlife Foundation of
Florida, African Safari Club International, Jennings Scholarship, and University
of Florida Department of Wildlife Ecology and Conservation. S. Simek, M. Cunningham,
J. Dixon, and D. Masters assisted with data collection, and A. Singh helped with
GIS analysis. M. Sunquist, G. Cumming, L.M. Conner, and two anonymous reviewers
provided helpful comments on an earlier draft of the manuscript, and FWC pilots
J. Wisniesky, J. Johnston, and P. Crippen assisted with radio-telemetry fl ights. This
study was also supported in part by the Florida Agricultural Experiment Station.
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