Denning, Pup-Rearing, and Dispersal in the Gray Fox in East-Central Alabama

Nicholson, W. S.; Hill, Edward P.; Briggs, D. J.

doi:10.2307/3801836

Cited by 46 publications

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“…Unlike males that tend to disperse at 1 year of age, females often remain on their natal territory until they are 2 years old (Roemer et al ). Similar patterns have been described for gray ( U. cinereoargenteus ; Nicholson et al ) and red foxes ( Vulpes vulpes ; Jensen , Storm et al , von Schantz ). In red foxes, young females are subordinate to their parents; they do not reproduce but instead care for their younger siblings (MacDonald ).…”

Section: Discussionsupporting

confidence: 72%

Factors Affecting Glucocorticoid and Thyroid Hormone Production of Island Foxes

et al. 2019

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The island fox (Urocyon littoralis) is native to 6 of the 8 Channel Islands of California, USA. The species experienced a population decline in the 1990s but recovered after predatory golden eagles (Aquila chrysaetos) were relocated and feral pigs (Sus scrofa), a main food source for the eagles, were removed. As part of an ongoing conservation program, the National Park Service conducts yearly health surveys on foxes residing on Santa Rosa and San Miguel islands. In this study, we document non‐invasive measures of stress and nutritional status from fecal samples collected during surveys from 2009 to 2015. We collected samples defecated in traps overnight or during handling and measured concentrations of glucocorticoid (GC) and triiodothyronine (T3) metabolites using validated assays. We used generalized linear mixed models to assess the relationships between hormones, season, island, age class, sex, body condition, reproductive status, and ectoparasite presence. Overall, males had marginally lower fecal T3 concentrations than females. Concentrations of both hormones positively correlated with body condition. Fecal GC production varied seasonally; concentrations were highest from December to February and declined through the summer and fall. During summer, younger females and those with signs of recent reproduction had higher fecal GC concentrations than older females or those without evidence of reproduction. Fecal T3 concentrations did not vary in relation to season, age, or reproductive status, but on San Miguel Island were positively correlated with ectoparasite presence. There were no other significant differences between islands. Our results provide hormone data for island foxes and demonstrate that production varies in relation to seasonal and biological factors. These reference data will serve as a comparison for future health surveys and allow managers to identify factors associated with increased stress or reduced nutritional state. © 2019 The Wildlife Society.

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Section: Discussionsupporting

confidence: 72%

Factors Affecting Glucocorticoid and Thyroid Hormone Production of Island Foxes

et al. 2019

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“…2. Predation by coyotes was an important source of mortality for gray foxes and, apparently, also for bobcats, contrasting with studies that implicate diseases and human-related factors as major causes of death (Nicholson et al 1985;Fuller and Berendzen 1995).…”

Section: Discussionmentioning

confidence: 92%

Competition and intraguild predation among three sympatric carnivores

et al. 2000

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We examined the relative roles of dominance in agonistic interactions and energetic constraints related to body size in determining local abundances of coyotes (Canis latrans, 8-20 kg), gray foxes (Urocyon cinereoargenteus, 3-5 kg) and bobcats (Felis rufus, 5-15 kg) at three study sites (hereafter referred to as NP, CP, and SP) in the Santa Monica Mountains of California. We hypothesized that the largest and behaviorally dominant species, the coyote, would exploit a wider range of resources (i.e., a higher number of habitat and/or food types) and, consequently, would occur in higher density than the other two carnivores. We evaluated our hypotheses by quantifying their diets, food overlap, habitat-specific abundances, as well as their overall relative abundance at the three study sites. We identified behavioral dominance of coyotes over foxes and bobcats in Santa Monica because 7 of 12 recorded gray fox deaths and 2 of 5 recorded bobcat deaths were due to coyote predation, and no coyotes died as a result of their interactions with bobcats or foxes. Coyotes and bobcats were present in a variety of habitats types (8 out of 9), including both open and brushy habitats, whereas gray foxes were chiefly restricted to brushy habitats. There was a negative relationship between the abundances of coyotes and gray foxes (P=0.020) across habitats, suggesting that foxes avoided habitats of high coyote predation risk. Coyote abundance was low in NP, high in CP, and intermediate in SP. Bobcat abundance changed little across study sites, and gray foxes were very abundant in NP, absent in CP, and scarce in SP; this suggests a negative relationship between coyote and fox abundances across study sites, as well. Bobcats were solely carnivorous, relying on small mammals (lagomorphs and rodents) throughout the year and at all three sites. Coyotes and gray foxes also relied on small mammals year-round at all sites, though they also ate significant amounts of fruit. Though there were strong overall interspecific differences in food habits of carnivores (P<0.0001), average seasonal food overlaps were high due to the importance of small mammals in all carnivore diets [bobcat-gray fox: 0.79±0.09 (SD), n=4; bobcat-coyote: 0.69±0.16, n=6; coyote-gray fox: 0.52±0.05, n=4]. As hypothesized, coyotes used more food types and more habitat types than did bobcats and gray foxes and, overall, coyotes were the most abundant of the three species and ranged more widely than did gray foxes. We propose that coyotes limit the number and distribution of gray foxes in Santa Monica Mountains, and that those two carnivores exemplified a case in which the relationship between their body size and local abundance is governed by competitive dominance of the largest species rather than by energetic equivalences. However, in the case of the intermediate-sized bobcat no such a pattern emerged, likely due to rarity or inconsistency of agonistic interactions and/or behavioral avoidance of encounters by subordinate species.

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“…Dispersal distances of male and female island foxes were also extremely limited compared with mainland fox species. In Alabama, Nicholson, Hill & Briggs (1985) recorded a mean dispersal distance of 15 km (sd 9.5) for three male grey foxes. The kit fox Vulpes macrotis, a North American canid similar in size to the island fox, has an average dispersal distance of 11.1 km (n = 47, range 1.7±31.5) (O'Farrell, 1984).…”

Section: Discussionmentioning

confidence: 99%

The behavioural ecology of the island fox (Urocyon littoralis)

et al. 2001

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Insular populations typically occur at higher densities, have higher survivorship, reduced fecundity, decreased dispersal, and reduced aggression compared to their mainland counterparts. Insularity may also affect mating system and genetic population structure. However, these factors have not been examined simultaneously in any island vertebrate. Here we report on the ecological, behavioural and genetic characteristics of a small carnivore, the island fox Urocyon littoralis, from Fraser Point, Santa Cruz Island, California. Dispersal distances in island foxes are very low (mean 1.39 km, sd 1.26, range 0.16±3.58 km, n = 8). Home-range size is one of the smallest (mean annual home range = 0.55 km 2 , sd 0.2, n =14) and density is nearly the highest recorded for any canid species (2.4±15.9 foxes/km 2 ). Similar to other fox species, island foxes are distributed as mated pairs that maintain discrete territories. Overlap among mated pairs was always high (mean 0.85, sd 0.05), while overlap among neighbours (mean 0.11, sd 0.13), regardless of sex, was low. Despite this high degree of territoriality, island foxes are not strictly monogamous. Four of 16 offspring whose parents were identi®ed by paternity analysis were a result of extra-pair fertilizations. Mated pairs were unrelated, however, suggesting inbreeding avoidance. Substantial population differentiation was found between the Fraser Point subpopulation and one only 13 km away (F st = 0.11). We suggest that the primary effect of ®nite island area is to limit dispersal, which then in¯uences the demography, behaviour and genetic structure of island fox populations.

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Denning, Pup-Rearing, and Dispersal in the Gray Fox in East-Central Alabama

Cited by 46 publications

References 0 publications

Factors Affecting Glucocorticoid and Thyroid Hormone Production of Island Foxes

Factors Affecting Glucocorticoid and Thyroid Hormone Production of Island Foxes

Competition and intraguild predation among three sympatric carnivores

The behavioural ecology of the island fox (Urocyon littoralis)

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