On the Fast Track to Recovery: Island Foxes on the Northern Channel Islands

Coonan, Timothy J.; Bakker, Victoria J.; Hudgens, Brian R.; Boser, Christina L.; Garcelon, David K.; Morrison, Scott

doi:10.3398/042.007.0128

Cited by 10 publications

(20 citation statements)

References 23 publications

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“…In the 1990s, fox numbers dropped rapidly due to the introduction of distemper by domestic dogs on Santa Catalina (Coonan et al, 2010) and by golden eagle predation on the northern Channel Islands (Roemer et al, 2002). Through a captive breeding and re-release program, however, fox populations have recovered dramatically on the northern islands (Coonan et al, 2010(Coonan et al, , 2014.…”

Section: The California Channel Islands and Island Foxes: What Do We mentioning

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

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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.

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Section: The California Channel Islands and Island Foxes: What Do We mentioning

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

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“…The dominant effect of demography across all island populations is a reduction in the efficacy of selection and a consequent increase in the load of deleterious variation. Nonetheless, the island populations appear healthy, can recover from disease epidemics, and the four recently bottlenecked populations recovered rapidly under human management after introduced non-native disease or predation threats were removed [26,27]. The unaided persistence of the San Nicolas population, and the successful recovery of the four endangered populations, contrasts with other cases in which loss of genetic diversity following population declines has resulted in apparent inbreeding depression, hampering recovery [28,29].…”

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confidence: 99%

Genomic Flatlining in the Endangered Island Fox

et al. 2016

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Genetic studies of rare and endangered species often focus on defining and preserving genetically distinct populations, especially those having unique adaptations [1, 2]. Much less attention is directed at understanding the landscape of deleterious variation, an insidious consequence of geographic isolation and the inefficiency of natural selection to eliminate harmful variants in small populations [3-5]. With population sizes of many vertebrates decreasing and isolation increasing through habitat fragmentation and loss, understanding the extent and nature of deleterious variation in small populations is essential for predicting and enhancing population persistence. The Channel Island fox (Urocyon littoralis) is a dwarfed species that inhabits six of California's Channel Islands and is derived from the mainland gray fox (U. cinereoargenteus). These isolated island populations have persisted for thousands of years at extremely small population sizes [6, 7] and, consequently, are a model for testing ideas about the accumulation of deleterious variation in small populations under natural conditions. Analysis of complete genome sequence data from island foxes shows a dramatic decrease in genome-wide variation and a sharp increase in the homozygosity of deleterious variants. The San Nicolas Island population has a near absence of variation, demonstrating a unique genetic flatlining that is punctuated by heterozygosity hotspots, enriched for olfactory receptor genes and other genes with high levels of ancestral variation. These findings question the generality of the small-population paradigm that maintains substantial genetic variation is necessary for short- and long-term persistence.

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“…Numerous native species have benefited from these restoration efforts (e.g., Corry and McEachern 2009, Sillett et al 2012, Coonan et al 2014, which represent substantial investments of time and funds. TNC and NPS have committed to implement biosecurity protocols to protect that investment and the resulting conservation gains and also to control the spread of invasive species to unaffected island sites and reduce the risk of reinfestation from the mainland (Boser et al 2014, Cory andKnapp, 2014).…”

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confidence: 99%