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Male Swamp Rabbit (Sylvilagus aquaticus) Habitat Selection at Multiple Scales
Karen B. Vale, and Robert E. Kissell, Jr.

Southeastern Naturalist, Volume 9, Issue 3 (2010): 547–562

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2010 SOUTHEASTERN NATURALIST 9(3):547–562 Male Swamp Rabbit (Sylvilagus aquaticus) Habitat Selection at Multiple Scales Karen B. Vale1, and Robert E. Kissell, Jr.1,* Abstract - Sylvilagus aquaticus (Swamp Rabbit) is of conservation concern throughout portions of its range, primarily due to habitat loss and alteration. Understanding habitat selection is requisite for natural resource managers providing suitable habitat to support populations of Swamp Rabbits. Swamp Rabbits are thought to be territorial and, as such, emphasis should be placed on males when studying habitat selection. Seasonal (dormant, growth, and senescent) habitat selection by male Swamp Rabbits was assessed at landscape, home-range, and plot scales. In each season, young (<20 yr) bottomland hardwood forests were selected in greater proportion, open field was selected intermediately, and old (>35 yr) bottomland hardwood forests were selected least relative to availability at the landscape scale. Male Swamp Rabbits selected home ranges from the landscape to include access to higher-elevation habitats, perhaps important during flood events. At the home-range scale, young bottomland hardwood forests and open fields were selected most during the dormant and senescent seasons, respectively, and old bottomland hardwood forests were selected least during the senescent season; the remaining cover types in each season were selected in proportion to their availability. At the home-range scale, locations with suitable cover were selected suggesting predation-risk was important at this scale. At the plot scale, predictor variables indicated Swamp Rabbits selected sites conducive to daytime resting, nighttime foraging, or latrine use. We present the first work that examines habitat selection of male Swamp Rabbits at multiple scales. Our results emphasize the importance of interspersion of cover types and stand age selected by male Swamp Rabbits. Introduction Habitat selection, the active process of choosing habitat at different scales, can drive distribution patterns because animals do not use the available habitat uniformly within their range (Hall et al. 1997, Krebs 1994). Habitat selection affects fitness, and animals select higher quality habitat within their range when available (Manly et al. 2002). Furthermore, habitat selection results in disproportional use of some resources and can occur across multiple scales (Hall et al. 1997, Johnson 1980). Distribution and selection of resources are thought to determine spatial organization, including home ranges and territories (Brown and Orians 1970). Male Sylvilagus aquaticus Bachman (Swamp Rabbits) are largely assumed to be territorial (Chapman and Flux 2008, Kjolhaug and Woolf 1988). 1School of Forest Resources, Arkansas Forest Resources Center, University of Arkansas at Monticello, Monticello AR 71656. *Corresponding author - kissell@ uamont.edu. 548 Southeastern Naturalist Vol. 9, No. 3 If males defend feeding or mating territories, then determining habitat selected by males is important for management, as reproductive success would depend upon understanding habitat characteristics of these locations and factors affecting habitat selection. Limited knowledge exists regarding the habitat ecology of Swamp Rabbits (Chapman and Feldhamer 1981). Much work has been conducted on distribution (Fowler and Kissell 2007, Scheibe and Henson 2003, Terrel 1972), occupancy (Roy Nielson et al. 2008), and latrine characteristics (Fowler and Kissell 2007, McCollum and Holler 1994, Zollner et al. 1996). Given the assumption that Swamp Rabbits are territorial, however, there is a gap in our understanding of male Swamp Rabbit ecology. Considering that the swamp rabbit is of conservation concern in portions of its range (Dailey et al., 1993, Kjolhaug et al. 1987, Korte and Fredrickson 1977), that it is assumed to be territorial, and that a paucity of information exists regarding the species, we assessed seasonal habitat selection by male Swamp Rabbits at the landscape (2nd order), home-range (3rd order), and plot (4th order) scales to determine cover types and habitat components most important in the core of its range. Methods Study area The study area, 91.9 ha in size, consisted of both private and industrial forest in Drew County, AR (33º25′N, 91º56′W). The industrial forest had active timber management on the site. Four cover types were identified: open field (OF); young bottomland hardwood forest (YBHF; <20 yrs); old bottomland hardwood forest (OBHF; >35 yrs), and clear cut (CC; <4 yrs). The OF was dominated by Andropogon spp. and Festuca spp. (various grasses) and contained several food plots. The YBHF was clear cut in 1990 (17%) and 1997 (87%) and allowed to regenerate naturally. The YBHF overstory was dominated by Quercus spp. (oak), Liquidambar styraciflua L. (Sweetgum), Carpinus caroliniana Walt. (American Hornbeam), and Ulmus alata Michx. (Winged Elm). The understory in the YBHF was diverse, but was primarily dominated by American Hornbeam, oak, Vaccinium spp., and Crataegus marshallii Eggl. (Parsley Hawthorn). Numerous paths 3–5 m wide were distributed throughout the YBHF. Portions of the OBHF were selectively cut in 1936 and 1976. The overstory was dominated by oak, American Hornbeam, and Sweetgum. The understory was sparse and dominated by Amercian Hornbeam, Vaccinium spp., and Ilex opaca Aiton (American Holly). The CC was cut in 2004 and was replanted with Pinus taeda L. (Loblolly Pine). Typical species other than pine included Rubus spp., Vaccinium spp., and Baccharis halimifolia L (Eastern Baccharis). Elevation ranged from 30.32–34.01 m and was different among cover types (CC [mean = 33.16 m] > OF [mean = 32.99 m] > YBHF [mean = 31.99 m] > OBHF [mean = 31.54 m]). 2010 K.B. Vale and R.E. Kissell, Jr. 549 Brown’s Creek intersected the study site, and a network of channels and sloughs branched off throughout the site. Seasonal flooding occurred throughout the study area, and portions of the site were inaccessible during periods of flooding. Mean annual temperature was 19.2 °C and ranged from -6.1 °C in January to 40.0 °C in August (NWS 2006–2008). Precipitation totaled 78.4 cm and ranged from 2.4 cm in August to 17.8 cm in July (NWS 2006–2008). Trapping procedures Forty collapsible Tomahawk live traps (70 x 25 x 25 cm; Tomahawk Live Trap Company, Tomahawk, WI) were set in areas where latrine sites, runs, and tracks indicated rabbit activity. Traps were placed ≥1 month in advance to habituate rabbits to their presence. Traps were covered with burlap and baited with various baits (Smyth et al. 2007). Trapping sessions of 2–22 days in length ran from 8 December 2006 to 25 March 2007, with traps checked daily. Captured rabbits were anesthetized using an intramuscular injection of 10 mg/kg ketamine hydrochloride and 2 mg/kg xylazine hydrochloride. Rabbits were weighed (g), measured (mm; hind foot length, ear length, tail length, total body length, and chest girth), and identified to sex. Rabbits weighing ≥1800 g were each fitted with a radiocollar (30–40 g) equipped with a 12-hr delay mortality sensor (Advanced Telemetry Systems, Isanti, MN); collars weighed <4% of the body weight as suggested by Cochran (1980). Each rabbit also received a numbered ear tag in each ear (Seber 1982; National Band and Tag Company, Newport, KY). Captured Swamp Rabbits were allowed to recover from sedation and released at the site of capture. Capture, handling, and release of Swamp Rabbits were performed following methods which adhered to the guidelines of the American Society of Mammalogists (Gannon et al. 2007) and were approved by the University of Arkansas at Monticello Institutional Animal Care and Use Committee (Approval #2006-2). Telemetry Collection of telemetry-based locations began ≥48 h post-capture to allow for recovery from the stress of capture. Collared rabbits were located 2–3 times per week for the study duration, until death, or until transmitter failure. Rabbits were located during 4 time blocks: early morning (00:01– 6:00 hr), late morning (6:01–12:00 hr), mid-day (12:01–18:00 hr), and evening (18:01–24:00 hr). We used 3 seasons to determine habitat selection. Seasons, based on general plant phenology, were dormant (January–March), growth (April–June), and senescent (July–October). Permanent telemetry stations (n = 21) were established throughout the study area utilizing a Trimble GeoXH Global Positioning System (GPS) unit. Rabbit locations were determined by triangulation (White and Garrott 1990, Zollner 1993) using an R-1000 telemetry receiver (Communications Specialists, Inc., Orange, CA) and an H-antenna. Azimuths were 550 Southeastern Naturalist Vol. 9, No. 3 recorded from 2 telemetry stations for each rabbit, and the intersection was considered the animal’s location (Heezen and Tester 1967, Herring and Collazo 2005, Nams and Boutin 1991). Bearings were taken ≤10 minutes apart. Only bearings having a difference of 60–120° were used. Universal Transverse Mercator coordinates of radio-collared Swamp Rabbits were determined using program Locate II (Nams 1990). Accuracy of bearing acquisition was determined seasonally using radio-collars placed at known locations. Home range Fixed kernel estimates (50, 90, and 95% contours; Kernohan et al. 2001, Seaman and Powell 1996, Seaman et al. 1999) were calculated using the ad hoc bandwidth method (Schroeder 2007) utilizing Home Range Tools for ArcGIS (Rodgers et al. 2007). The ad hoc bandwidth method is similar to least squares cross validation in that the reference bandwidth is reduced gradually, but the ad hoc bandwidth is chosen just before the 95% kernel home range contour is separated into >1 polygon (Schroeder 2007). Choosing a bandwidth just before the contour is separated into >1 polygon provides connectivity among all areas of the home range. Seasonal home ranges were calculated only for animals with ≥30 locations (Seaman et al. 1999). Habitat use We developed a cover-type map by digitizing a 2006 aerial photograph for 2nd and 3rd order habitat selection. Cover types within the study area boundary were classified based on management history and vegetative characteristics. The study site boundary was determined by buffering all rabbit locations a distance of one-half the mean maximum distance moved (Wilson and Anderson 1985). Only 1 male rabbit’s home range included CC; therefore, this cover type and rabbit were omitted from 2nd and 3rd order assessments. Available habitat was determined using 1000 randomly selected points within the study area for 2nd order selection. Available 3rd order habitat was determined using 30 randomly selected points within each 95% fixed kernel home range. Fourth-order selection was quantified by measuring vegetation and other physical characteristics from 20 April 2007–20 March 2008 at rabbit locations identified by radio-telemetry and at random locations. Random locations were identified with random distances and bearings from rabbit locations, and were between 50–250 m from estimated rabbit locations (Porath 1997, Seamans and Guttierrez 1995). We measured mean canopy cover using a concave densitometer; 1 measurement was taken at plot center and, 4 measurements were taken 5 m from plot center in each cardinal direction (Zollner 1993, Zollner et al. 2000a). We measured mean horizontal visibility using a 0.5-m x 0.5-m density board (Wagner et al. 2000) to indicate understory vegetation cover. 2010 K.B. Vale and R.E. Kissell, Jr. 551 Density-board measurements were taken in each cardinal direction 10 m from plot center. We measured horizontal visibility from ground level to 0.5 m above ground and from 0.5 m to 1 m above ground. Downed logs and stumps ≥7.6 cm diameter and within 10 m of plot center were enumerated and measured (Payer and Harrison 2003). Measurements included decay class (Brown et al. 1998, Dingledine and Haufler 1983), log circumference (at center), and presence of moss and rabbit fecal pellets (Fowler and Kissell 2007). Decay classes were 1–6, with a greater number indicating more decay. Latrines within 10 m of each location were also enumerated. Number of pellets present and type of latrine (stump, log, or ground) were recorded. Latrine sites were characterized as sites with at least 1 fecal pellet, and pellets within 1 m of each other were considered 1 latrine site (Zollner et al. 1996). We measured the distance from plot center to permanent and temporary water sources using GIS. Temporary water included ephemeral pools and sloughs holding water for ≥1 month but not more than 9 months. Permanent water sources were those holding water for 10–12 months per year. We measured distance between animal locations and each of the 4 cover types using GIS. Tree density and composition were measured using the point-quarter method (James and Shugart 1970). The nearest tree in each quarter was identified to species, and diameter at breast height (dbh) and distance from plot center (m) were measured. Only trees with a dbh of ≥10.2 cm (Ellis and Whelan 1978, Korte 1975) and >5 m tall (McCollum 1992) were included. Shrub density and composition were measured using the same methods as tree density and composition, except the nearest shrub in each quarter was identified to species, and distance (m) and height (m) were measured. Only shrubs with a dbh of <10.2 cm and height of 1–5 m were included (Fischer and Holler 1991, McCollum 1992). Plant nomenclature followed Miller and Miller (2005). Density of understory vegetation >5 m tall and with a dbh <10.2 cm was measured by counting the number of stems within five 2-m2 quadrats: one at plot center and one 5 m from plot center in each cardinal direction. Ground cover was quantified by ocular estimation using five 1-m2 sampling quadrats and 6 coverage classes at each site. Percent cover for grasses/ sedges, bare ground, vines, forbs, leaf litter, and other were recorded. The 6 cover classes were 0–5%, 6–25%, 26–50%, 51–75%, 76–95%, and 96–100% (Daubenmire 1959). Quadrats were placed at plot center and 5 m from plot center in each cardinal direction. We recorded the presence of browse species, including Bignonia capreolata L. (Crossvine), Smilax spp. and Rubus spp. (briar), Gramineae (grasses), Carex spp. (sedges), Toxicodendron radicans (L.) Kuntze (Poison Ivy), and Arundinaria gigantea (Walter) Muhl. (Giant Cane), within 10 m of plot center. Data on maximum and minimum daily temperature and precipitation during the study were obtained from the Monticello Municipal Airport, located approximately 29 km from the study area (NWS 2006–2008). 552 Southeastern Naturalist Vol. 9, No. 3 We analyzed habitat selection at the landscape and home-range scales (i.e., 2nd and 3rd orders) using Euclidean distance analysis (DA; Conner and Plowman 2001). We chose DA because it provides desirable characteristics to analyze habitat selection (Aebischer et al. 1993), is robust to telemetry error, and provides results that allow for the evaluation of effect size. Additionally, DA performs well in terms of meeting type-I error rates compared to other techniques (Bingham and Brennan 2004). The DA approach uses the ratio of distances to each cover type from known locations of each animal to the distances from random locations to each cover type to determine if habitat use is random. If use is random, the ratio should equal 1. If the ratio is <1 then the animal uses the cover type more than expected and if the ratio is >1 then the animal uses the cover type less than expected. We used GIS to calculate the vectors of distance ratios (di) for each cover type. We used multivariate analysis of variance to determine if random locations differed from Swamp Rabbit locations at both the landscape and home-range scales. If differences were found, we used a t-test to determine which cover types were used non-randomly. The t-tests were used for pairwise comparisons to determine if a given cover type was used significantly more than another. We ranked cover types by season based on increasing values of di (Conner and Plowman 2001). Statistical Analysis Software version 9.1 (SAS Institute, Inc. 2002–2003) was used to perform the DA using α = 0.05. At the plot scale (i.e., 4th order), we analyzed factors affecting habitat selection at rabbit locations in each season using stepwise logistic regression. Variables not normally distributed or showing evidence of heteroscedasticity (P ≤ 0.05) were transformed to meet assumptions of parametric statistical analysis. Count and percentage data were log and arcsine square root transformed, respectively. Only uncorrelated (r2 < 0.60) habitat variables, as determined by Pearson correlation, were included in logistic regressions. Variables were entered into the model at α = 0.10 and were retained in the model at α = 0.15. Statistical Analysis Software version 9.1 (SAS Institute, Inc. 2002–2003) was used to perform logistic regression. Results Fourteen Swamp Rabbits were captured, including 3 adult females, 10 adult males, and 1 juvenile male; of these, 5 recaptures occurred. All 13 adult Swamp Rabbits were fitted with radio-collars, but we only included adult males in the analyses. Mean bearing error of location acquisition was 8.6° (SE = 0.8). Mean distance between telemetry stations and known collar locations was 107.3 m (SE = 8.0). Sufficient data was collected during the dormant, growth, and senescent seasons such that we used 6, 8, and 6 male rabbits, respectively, in landscape and home-range scale analyses. At the landscape scale, Swamp Rabbits selected cover types disproportionately (Table 1) during the dormant (F3,3 = 3108, P < 0.001), growth 2010 K.B. Vale and R.E. Kissell, Jr. 553 (F3,5 = 15016, P < 0.001), and senescent seasons (F3,3 = 172349, P < 0.001). Each season, male Swamp Rabbits were found closer to YBHF and OF than expected, and farther from OBHF than expected. The pattern of selection was consistent across seasons, and use differed significantly among cover types within each season. Ranking was YBHF > OF > OBHF each season. At the home-range scale, Swamp Rabbits selected cover types disproportionately during the dormant (F3,3 = 202.7, P = 0.001) and senescent (F3,3 = 8.16, P = 0.059) seasons (Table 2); during the growth season, cover types were used in proportion to availability (F3,5 = 1.08, P = 0.437). Male Table 1. Landscape-scale (2nd order) habitat selection results using the Euclidean distance analysis for male Swamp Rabbits in southeastern Arkansas from January 2007–October 2007 Season Cover typeA SelectionB MeanC DifferenceD Dormant OF > -0.451 A YBHF > -0.984 B OBHF < 0.449 C Growth OF > -0.515 A YBHF > -0.974 B OBHF < 0.481 C Senescent OF > -0.601 A YBHF > -0.983 B OBHF < 0.686 C AOF = open field, YBHF = young bottomland hardwood forest, and OBHF = old bottomland hardwood forest. BSelection compared to expected. CDifference between the expected vector of distance ratios of used versus available and 1. DDifferent letters indicate a significant difference in the use between cover types. Table 2. Home-range scale (3rd order) habitat selection results using the Euclidean distance analysis for male Swamp Rabbits in southeastern Arkansas from January 2007–October 2007. Season Cover typeA SelectionB MeanC DifferenceD Dormant OF = -0.017 A YBHF > -0.893 B OBHF = 0.111 A Growth OF = -0.031 A YBHF = -0.478 A OBHF = 0.107 A Senescent OF > -0.216 A YBHF = -0.197 AB OBHF < 0.113 B AOF = open field, YBHF = young bottomland hardwood forest, and OBHF = old bottomland hardwood forest. BSelection compared to expected. CDifference between the expected vector of distance ratios of used versus available and 1. DDifferent letters indicate a significant difference in the use between cover types. 554 Southeastern Naturalist Vol. 9, No. 3 Swamp Rabbits were found closer to YBHF than expected and used OF and OBHF in proportion to their availability during the dormant season. Use differed between the YBHF and the other cover types within the dormant season. Ranking was YBHF > OF > OBHF during the dormant season. Male Swamp Rabbits were found closer to OF than expected, farther from OBHF than expected, and used YBHF in proportion to its availability during the senescent season. Use differed between the OF and OBHF cover types within the senescent season; use of the YBHF did not differ between the other two cover types. Ranking was OF > YBHF > OBHF during the dormant season. We analyzed 267 rabbit locations (dormant, n = 73; growth, n = 85; senescent, n = 109) and 267 random locations (dormant, n = 73; growth, n = 85; senescent, n = 109) for plot-scale assessment. Twenty-five variables had Pearson correlation coefficients < 0.60 and were used in logistic regressions. Plot-scale results (Table 3) indicated rabbit locations contained 29.7% higher understory cover, logs 2.8% more decomposed, 33.0% more stumps with moss, and 31.7% more forb ground cover compared to random locations during the dormant season. During the growth season, rabbit locations were 31.5% further away from old bottomland hardwood forest, contained logs 8.3% larger in diameter, and had 53.5% less bare ground cover compared to random locations. During the senescent season, rabbit locations contained logs 3.3% larger in diameter, 58.0% more ground cover of vines, and 31.2% less bare ground cover compared to random locations. Discussion Higher elevation sites, such as those in the YBHF and OF, serve as an important refuge during flood events (Conaway et al. 1960, Hastings 1954, Smith and Zollner 2001, Smyth et al. 2007). There was extensive flooding on the study site during the dormant season; OBHF was used significantly less during this time, indicating Swamp Rabbits moved away from flood water and used Table 3. Seasonal logistic regression models that best separated male Swamp Rabbit locations (n = 267) from random locations (n = 267) at 4th order scale of habitat selection (January 2007–October 2007). Season Variable d.f. Estimate SE Wald chi-square P-value Dormant Density board visible 1 -0.5883 0.24 5.8140 0.0159 Log decomposition 1 -6.6381 3.30 4.0519 0.0441 Stumps with moss 1 -0.2185 0.13 2.7440 0.0976 Forb ground cover 1 -9.0790 3.05 8.8365 0.0030 Growth Distance to OBHF 1 -0.1115 0.05 4.8593 0.0275 Log diameter 1 -2.4577 1.15 4.6002 0.0320 Bare ground cover 1 -5.7487 2.01 8.1902 0.0042 Senescent Log diameter 1 -1.6018 0.75 4.5382 0.0331 Vine ground cover 1 -2.6526 1.61 2.7251 0.0988 Bare ground cover 1 -4.5481 1.73 6.8981 0.0086 2010 K.B. Vale and R.E. Kissell, Jr. 555 upland areas more frequently. Flooding is typical in bottomland hardwood forests, and may cause mortality (Hastings 1954), higher vulnerability to hunting and predator pressure (Layne 1958), and decreased availability of food and cover (Korte 1975). YBHF provided a combination of higher elevation and suitable cover. Although OF was selected intermediately, it may be important for rabbits to have access to this cover type, or a similar, higher-elevation cover type, to have refuge during flooding events. Zollner et al. (2000b) found female Swamp Rabbits used cover types differently in response to flooding. Smith and Zollner (2001) recognized the effect of seasonal flooding on habitat use of Swamp Rabbits in Arkansas and suggested habitat quality may depend on the availability of adjacent, upland areas as much as the composition and structure of lowland areas. Flooding events may occur at any time of year on the site we studied. Swamp Rabbits likely selected home ranges from the landscape to minimize the effect of flooding, and selected areas that maximized cover and refuge from flooding events. At the home-range scale during the dormant season, males selected locations within the YBHF most often perhaps due to availability of cover and food resources. Considering Swamp Rabbits are opportunistic feeders that adapt to a variety of food sources, such as grasses, sedges, woody stems, forbs, tree seedlings (Terrel 1972, Toll et al. 1960), and given the high availability of forage year round in the southeastern United States (Allen 1985), available cover may be more important than available forage at this scale. Cover is the most critical factor required by Swamp Rabbits (Allen 1985), and we think Swamp Rabbits were selecting locations within their home ranges based on predation risk rather than food availability. The other cover types were used in proportion to their occurrence, and this result reflects the limited amount of either cover type that occurred in the home ranges during this season. YBHF had a dense understory layer of saplings, shrubs, and groundcover due to a moderately open canopy following clear cutting in 1997. This cover type provided ample food and cover resources essential for suitable Swamp Rabbit habitat (Allen 1985, Whitaker and Abrell 1986). Lay and Taylor (1943) suggested 10–15 yr-old clear-cut areas with established dense brush were optimum Swamp Rabbit habitat in Texas. Several studies suggest moderate-sized clear cuts and improvement cuts as a way to enhance Swamp Rabbit habitat by creating canopy gaps to increase understory density (Hurst and Smith 1986, Korte 1975). For example, Korte (1975) suggested creating openings 0.1–0.5 ha several hundred meters apart in even-aged forests to improve habitat for Swamp Rabbits in Missouri. Likewise, Hurst and Smith (1986) recommended a silvicultural practice that includes 4–8 ha clear cuts and periodic improvement cuts throughout a stand’s rotation in Mississippi. Cover types were selected in proportion to their availability during the growth season at the home-range scale. Extensive vegetative growth 556 Southeastern Naturalist Vol. 9, No. 3 throughout the study area may have enabled rabbits to move into areas not typically used during other seasons. Grasses within the OF were tall enough to provide cover from predators during the growth season, and rabbits may have been more apt to use the OF as a result. Likewise, vegetative growth in the OBHF also likely provided sufficient cover and forage to be used in proportion to its availability. The importance of habitat selection in rabbits is most often related to cover and avoiding predation (Iason et al. 2002), but the importance of cover for rabbits may be seasonal (Rueda et al. 2008). Rabbits will make use of areas with more vegetation, especially during the growth season, when vegetation provides for both forage and cover (Rueda et al. 2008). The senescent season was the driest and hottest season, and the OF was cut during this time. Associated with the reduced available cover in the OF was access to new plant growth. Conversely, Swamp Rabbits likely limited their time in the OBHF because of the limited and desiccated forage and lack of cover. The YBHF likely provided cover and was in proximity to the OF. This combination of cover types likely satisfied the need for cover and forage during this time of the year. In all seasons at the plot scale, habitat variables predicting Swamp Rabbit locations appeared related to latrine use, foraging, or daytime resting sites (Zollner et al. 2000a). During the dormant season, greater shrub cover related to daytime resting sites, greater decomposition of logs and greater numbers of stumps with moss related to latrine sites, and greater ground cover of forbs were reflective of foraging areas. Zollner et al. (2000a) found daytime resting sites correlated with higher percentage of shrubs and downed tree tops in Arkansas, habitat factors which they attributed to predator avoidance and weather-related hazards. Allen (1985) postulated optimum shrub canopy closure as ≥50%; we found mean shrub cover at rabbit locations to be ≈69%. Although methodology varied with these studies, results illustrate the importance of a dense shrub layer for Swamp Rabbits. We also found highly decomposed logs and mossy stumps to be important predictors of rabbit locations during the dormant season. Highly decomposed, mossy logs and stumps are known to serve as latrine sites (Fowler and Kissell 2007, Smyth et al. 2007, Zollner et al. 1996). If latrine sites are used for information exchange or territorial marking, the rotted, mossy substrate may act as an absorptive surface allowing olfactory scent to last longer (Sneddon 1991, Zollner et al. 1996). Amount and decomposition of woody debris varies with stand age and development, and although young clear cuts have been found to have increased amounts of coarse woody debris (Patterson et al. 2008), decayed logs are generally not present (Idol et al. 2001, McCarthy and Bailey 1994). Stands 10–100 yrs old typically have fewer logs, but are more decomposed (Idol et al. 2001, Jenkins and Parker 1997). Swamp Rabbits may have selected locations within the stand old enough to contain adequately decomposed woody debris. 2010 K.B. Vale and R.E. Kissell, Jr. 557 Swamp Rabbits are opportunistic feeders and have been found to consume plants in order of their abundance (Toll et al. 1960). However, Fowler and Kissell (2007) noted the importance of B. capreolata in swamp rabbit occurrence in Arkansas. During the dormant season, there was not an abundance of forbs on this site. Garner (1969) found Swamp Rabbits fed primarily on forbs during the spring (62%) and summer (94%) in Louisiana; winter forage consisted primarily of grasses (77%). However, results indicated Swamp Rabbits were selecting sites with more forbs available despite being in low abundance. During the growth season, greater distance to OBHF, greater log diameter, and less bare ground cover were likely related to daytime resting sites, latrine sites, and foraging areas, respectively. The OBHF had dense overstory canopy cover (mean = 87.1% at rabbit locations), outside the range (25–60%) suggested by Allen (1985) for optimal overstory canopy closure. Greater overstory canopy cover reduced the amount of understory vegetation, such as saplings, shrubs, forbs, vines, and grasses, which may be utilized as cover or food by Swamp Rabbits. Similar to the decomposition of logs and number of mossy stumps, greater log size is likely related to latrine use. Whitaker and Abrell (1986) suggested Swamp Rabbits use elevated objects to get a better view of their surroundings and reduce predation risk. Results indicated log height may have been important for Swamp Rabbits during the growth season when greater vegetative growth may have obstructed their view. Zollner et al. (2000a), however, did not find a relationship between shrub ground cover and sites used as latrines during spring–summer (May–August) or fall– winter (October–January) seasons. Less bare ground cover used during the growth season may have been a result of the abundance of the other ground-cover categories available during this season, none of which were important by themselves. Areas with less bare ground were more likely to have more forage items, such as forbs, grasses, and vines. Greater log size, less bare ground cover, and more vine cover during the senescent season represented latrine use, foraging areas, and daytime resting areas. If Swamp Rabbits were using larger logs during times of greater vegetative growth to improve their view, larger logs should be less important during the senescent season. However, Swamp Rabbits were using larger logs despite the reduction of vegetative growth. Our findings are not consistent with the vigilance hypothesis put forth by Whitaker and Abrell (1986), and the importance of log size remains unknown. Vines are an important food source for Swamp Rabbits (Allen 1985, Smith 1982). Low tangles of vines also provide excellent cover for Swamp Rabbits (Allen 1985). There was an abundance of vines available throughout the study period, but they may have become more important as food and cover during the senescent season when herbaceous vegetation decreased in abundance. 558 Southeastern Naturalist Vol. 9, No. 3 It appears that male Swamp Rabbits in southeastern Arkansas selected home ranges at the landscape scale to include higher elevation habitats needed during times of flooding, suitable cover and forage at the homerange scale depending on season, and fine-scale variables to provide for maintenance activities at the plot scale. This is the first assessment of habitat selection at multiple scales that demonstrates the importance of the spatial and temporal use of cover types by Swamp Rabbits. Acknowledgments We thank the University of Arkansas at Monticello for providing funding, and the Hyatt Family and Larson and McGowin, Inc., for use of their land. We are grateful to J. Earl, J.P. Kenny, J. Kidd, and B. 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