Gray Fox (Urocyon cinereoargenteus)
Home Range and Habitat Use
ResultsWe estimated 74 seasonal home ranges for 32 adult gray fox (15 male, 17 female). Home range size did not differ between sexes (P = 0.753), but did among seasons (P = 0.032) with largest home ranges during breeding-denning (353 ha). Home range sizes were similar during whelping-pup rearing and fall-winter. Similarly, core area size did not differ between sexes (P = 0.746), but did among seasons (P = 0.052). Core areas were largest during breeding-denning (37.2 ha) and smallest during fall-winter (20.0 ha).
Within seasons, gray fox selected habitats differently during breeding-denning (P <0.001), whelping-pup rearing (P = 0.002), and fall-winter (P <0.001) than the availability of habitats across the study area. Gray fox consistently selected mature pine stands when establishing home ranges during breeding-denning and whelping-pup rearing. During fall-winter, pine stands of 9-15 and mixed stands were most selected.
Within seasons, selection of habitats when establishing core areas did not differ relative to home range availability during breeding-denning (P = 0.113) or whelping-pup rearing (P = 0.191). However, core area selection differed relative to home range availability during fall-winter (P = 0.025). Overall, core areas across seasons contained greater proportions of mature pine and hardwood than other available habitats.
Within seasons, habitat use within home ranges did not differ relative to home range availability during breeding-denning (P = 0.434), whelping-pup rearing (P = 0.204), or fall-winter (P = 0.271). Overall, gray fox used mature pine and mixed stands most, whereas mature hardwood stands were least used.
SummaryPrevious studies examining sex-specific home ranges have suggested that home ranges are similar between sexes. Indeed, male and female gray foxes on TWMA maintained similar size home ranges and core areas. Similarly, other studies have reported a lack of significant differences in gray fox home ranges across seasons home ranges; gray fox on TWMA and GP maintained largest home ranges during breeding-denning. In fact, other studies have reported similar increases in gray fox home ranges during mating seasons, presumably due to increased movements from mating activities. We suggest that the large observed home ranges and core areas during breeding-denning on TWMA and GP were likely a function of efforts to locate optimal den locations and resource availability. Den selection could influence pup survival and adult fitness, thus gray fox may expand home ranges to search for den sites.
Habitat selection did not differ between sexes, suggesting that male and female gray foxes select habitats at all spatial scales we measured similarly. Gray foxes are assumed to be monogamous and nearly half of gray foxes we monitored frequently traveled with another fox and shared home ranges. Hence, it is not surprising that habitat selection was similar between sexes. Gray fox consistently selected mature pine stands at all spatial scales and in nearly all seasons. In 1994, most mature pine stands on TWMA were placed under management schemes directed to benefit red-cockaded woodpecker populations. Mature pine stands thinned and burned contain greater herbaceous vegetation compared to other stands and produce abundant gray fox prey. Small mammal abundance was greatest in mature pine stands on TWMA compared to other habitat types, hence selection of these habitats was likely a function of high prey abundance. Additionally, gray fox on TWMA and GP selected mature hardwoods at the core area level. Small mammals were abundant in these habitats compared to other habitats available within home ranges. Thus, selection of mature hardwood stands was likely a function of prey availability. Management Implications
Mature pine and hardwood habitats were important to gray fox when establishing home ranges and core areas and were frequently used in most seasons. Managers interested in maintaining gray fox populations should consider the importance of these habitats to gray fox. Management schemes directed towards gray fox in areas witnessing increasing conversions to short-rotation softwood habitats should recognize these gray fox habitat selection patterns at multiple scales.