Reproductive Ecology and Characteristics of Denning Sites of the San Clemente Island Fox

Resnik, Jessica R.; Andelt, William F.

doi:10.1894/0038-4909-57.2.170

Cited by 9 publications

(5 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although foxes give birth in late April and early May on the northern islands, with mothers lactating for ~7-9 weeks and pups emerging from the den in the early summer (Moore and Collins, 1995), parturition seems earlier on the southern islands. Powers (2009) found that foxes had litters from early to mid-March on San Nicolas Island, while Resnick and Andelt (2012) reported that parturition occurred as early as mid-February on San Clemente Island. The juvenile foxes from SCLI-1524 are less than two months of age based on dental eruption (Hale and Salls, 2000).…”

Section: Late Holocenementioning

confidence: 99%

Tracking the origins and diet of an endemic island canid (Urocyon littoralis) across 7300 years of human cultural and environmental change

Hofman

Rick

Maldonado

et al. 2016

Quaternary Science Reviews

View full text Add to dashboard Cite

Understanding how human activities have influenced the foraging ecology of wildlife is important as our planet faces ongoing and impending habitat and climatic change. We review the canine surrogacy approach (CSA)-a tool for comparing human, dog, and other canid diets in the past-and apply CSA to investigate possible ancient human resource provisioning in an endangered canid, the California Channel Islands fox (Urocyon littoralis). We conducted stable isotope analysis of bone collagen samples from ancient and modern island foxes (n=214) and mainland gray foxes (Urocyon cinereoargenteus, n=24). We compare these data to isotope values of ancient humans and dogs, and synthesize 29 Accelerator Mass Spectrometry (AMS) radiocarbon dates that fine-tune the chronology of island foxes. AMS dates confirm that island foxes likely arrived during the early Holocene (>7300 cal BP) on the northern islands in the archipelago and during the middle Holocene (>5500 cal BP) on the southern islands. We found no evidence that island foxes were consistently using anthropogenic resources (e.g., food obtained by scavenging or direct provisioning by Native Americans), except for a few individuals on San Nicolas Island and possibly on San Clemente and Santa Rosa islands. Decreases in U. littoralis carbon and nitrogen isotope values between prehistoric times and the 19 th century on San Nicolas Island suggest that changes in human land use from Native American hunter-gatherer occupations to historical ranching had a strong influence on fox diet. Island foxes exhibit considerable dietary variation through time and between islands and have adapted to a wide variety of climatic and cultural changes over the last 7300 years. This generalist foraging strategy suggests that endemic island foxes may be more resilient to future changes in resource availability.

show abstract

Section: Late Holocenementioning

confidence: 99%

Tracking the origins and diet of an endemic island canid (Urocyon littoralis) across 7300 years of human cultural and environmental change

Hofman

Rick

Maldonado

et al. 2016

Quaternary Science Reviews

View full text Add to dashboard Cite

show abstract

“…We found less annual site fidelity for San Clemente Island foxes than expected based on findings that foxes on Santa Cruz Island were territorial (Roemer et al ) and maintained similar home range sizes year‐round (Crooks and Van Vuren ). We speculate that low reproductive success during 2007 (Resnik and Andelt ) could have produced less site fidelity, and perhaps a smaller difference in seasonal home range and core area size between sexes, than might occur during years of higher reproductive success. Our findings that males had more home range fidelity than females supports previous findings that male and female island foxes care for young (Garcelon et al ), but only male island foxes form and maintain territories (Roemer et al ).…”

Section: Discussionmentioning

confidence: 97%

“…Following Roemer et al () and Kitchen et al (), we identified biologically relevant seasons by using the reproductive chronology of San Clemente Island foxes (Resnik and Andelt ): breeding and gestation (breeding; 15 Oct 2006–14 Feb 2007), parturition and pup‐dependence (pup‐dependence; 15 Feb–14 June 2007), and pup‐independence and dispersal (pup‐independence; 15 Jun–14 Oct 2007). We estimated site fidelity among seasons for individual foxes by dividing the area of intersection for 2 seasonal home ranges (or core areas) by the union of the home ranges (or core areas; Millspaugh et al ).…”

Section: Methodsmentioning

confidence: 99%

“…We used Location of a Signal software (Ecological Software Solutions, Urnäsch, Switzerland) to estimate UTM locations of foxes and set objective thresholds for including data (Resnik ). We estimated home ranges using the animal movement SA extension (Hooge and Eichenlaub ) in ArcView 3.3 (Environmental Systems Research Institute, Redlands, CA, USA), the kernel density estimator (Silverman ; Worton , ), fixed smoothing technique (Seaman and Powell ), and least‐squares cross‐validation (LSCV) for bandwidth selection (Worton , Seaman et al , Powell ).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Island fox spatial ecology and implications for management of disease

et al. 2016

View full text Add to dashboard Cite

Disease, predation, and genetic isolation resulted in 4 of 6 island fox (Urocyon littoralis) subspecies being listed as endangered in 2004. Potential for disease outbreaks continues to pose a major threat to the persistence of these isolated, endemic populations. We examined how roads influence the spatial ecology of San Clemente Island foxes (U. l. clementae), particularly in regard to spread of disease, to provide management recommendations for preventing or minimizing a disease outbreak on San Clemente Island, California, USA. Home range areas (truex¯ = 0.75 km2) and core areas (truex¯ = 0.19 km2) of foxes on San Clemente Island were 0.36–1.23 and 2.17 times larger, respectively, than estimates from Santa Cruz Island foxes (U. l. santacruzae). Home ranges and core areas were 78% larger and 73% larger, respectively, for foxes near roads than for foxes away from roads. Home ranges were also largest when foxes were not caring for offspring (i.e., seasons of pup‐independence and breeding). We did not detect any dispersal movements, but foxes living near roads moved 33% farther in 2‐hours periods than foxes not living near roads. Foxes near roads move faster, range more widely, and could more rapidly spread a pathogen throughout the island; therefore, roads might serve as transmission corridors. We recommend reducing this risk by increasing widths of vaccination firewalls (areas where vaccination is used to induce a disease‐resistant or immune population of foxes), ensuring these areas deliberately intersect roads, and vaccinating a higher proportion of foxes living near roads. Disease risk models incorporating these strategies could inform the lowest risk scenarios. © 2018 The Wildlife Society.

show abstract

“…This threshold was chosen because it was approximately half the radius of the previously reported average SCI fox home range size (Spencer et al. ; Resnik ). Foxes with measured home ranges that were near one another but did not overlap still had the potential to encounter one another while maintaining home range boundaries or during occasional forays outside their primary home range areas (White and Harris ).…”

Section: Methodsmentioning

confidence: 99%

Interactions between density, home range behaviors, and contact rates in the Channel Island fox (Urocyon littoralis)

Sánchez

Hudgens²

2015

Ecology and Evolution

View full text Add to dashboard Cite

Many of the mechanisms underlying density-dependent regulation of populations, including contest competition and disease spread, depend on contact among neighboring animals. Understanding how variation in population density influences the frequency of contact among neighboring animals is therefore an important aspect to understanding the mechanisms underlying, and ecological consequences of, density-dependent regulation. However, contact rates are difficult to measure in the field and may be influenced by density through multiple pathways. This study explored how local density affects contact rates among Channel Island foxes (Urocyon littoralis) through two pathways: changes in home range size and changes in home range overlap. We tracked 40 radio-collared foxes at four sites on San Clemente Island, California. Fox densities at the four sites ranged from 2.8 ± 1.28 to 42.8 ± 9.43 foxes/km2. Higher fox densities were correlated with smaller home ranges (R2 = 0.526, F1,38 = 42.19, P < 0.001). Thirty foxes wore collars that also contained proximity loggers, which recorded the time and duration of occasions when collared foxes were within 5 m of one another. Contact rates between neighboring fox dyads were positively correlated with home range overlap (R2 = 0.341, P = 0.008), but not fox density (R2 = 0.012, P = 0.976). Individuals at high densities had more collared neighbors with overlapping home ranges (R2 = 0.123, P = 0.026) but not an increase in the amount of contact between individual neighbors. This study was the first time contact rates were directly measured and compared to density and home range overlap. Results suggest that foxes exhibit a threshold in their degree of tolerance for neighbors, overlap is a reliable index of the amount of direct contact between island foxes, and disease transmission rates will likely scale with fox density.

show abstract

Reproductive Ecology and Characteristics of Denning Sites of the San Clemente Island Fox

Cited by 9 publications

References 20 publications

Tracking the origins and diet of an endemic island canid (Urocyon littoralis) across 7300 years of human cultural and environmental change

Tracking the origins and diet of an endemic island canid (Urocyon littoralis) across 7300 years of human cultural and environmental change

Island fox spatial ecology and implications for management of disease

Interactions between density, home range behaviors, and contact rates in the Channel Island fox (Urocyon littoralis)

Contact Info

Product

Resources

About