Diet patterns of island foxes on San Nicolas Island relative to feral cat removal

Cypher, Brian L.; Kelly, Erica C.; Ferrara, Francesca J.; Drost, Charles A.; Westall, Tory L.; Hudgens, Brian R.

doi:10.1071/pc16037

Cited by 22 publications

(13 citation statements)

References 19 publications

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“…Cats consumed significantly more lizards in years following dry bio‐years than normal bio‐years. This pattern is likely partially due to decreased rodent abundance following dry bio‐years, as deer mice populations are positively correlated with precipitation on the Channel Islands (Drost & Fellers, ; Cypher et al ., ) and our rodenticide consumption data suggest lower rodent abundance following dry bio‐years (Fig. d).…”

Section: Discussionmentioning

confidence: 53%

“…Similar to our results, Cypher et al . () also documented complex relationships between precipitation, prey availability, and predation patterns of foxes, highlighting the importance of long‐term studies to evaluate the diet of species in dynamic ecosystems.…”

Section: Discussionmentioning

confidence: 96%

“…Understanding how predation patterns are linked to weather will be integral to conservation success as climate change continues. Climate can affect both prey availability and nutritional requirements (Konecny, ; Drost & Fellers, ; Cypher et al ., ; Szép et al ., ), resulting in novel predation patterns and new threats for prey species. Cats consumed significantly more lizards in years following dry bio‐years than normal bio‐years.…”

Section: Discussionmentioning

confidence: 99%

“…Cypher et al . () documented increased consumption of vertebrate prey by foxes after the eradication of cats from nearby San Nicholas Island, suggesting that cats may exclude foxes from use of preferred prey. Phillips et al .…”

Section: Discussionmentioning

confidence: 99%

“…Cats also prey upon invasive black rats Rattus rattus and house mice Mus musculus . Cats compete with sympatric native predators including the SC island fox ( Urocyon littoralis clementae ; Phillips, Winchell & Schmidt, ; Cypher et al ., ), SC loggerhead shrike, and native raptors. We sampled stomachs from removed cats and analyzed the presence and abundance of rodents, lizards, birds, and other prey.…”

Section: Introductionmentioning

confidence: 99%

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Precipitation and prey abundance influence food habits of an invasive carnivore

Parsons¹,

Bridges²,

Biteman³

et al. 2019

Animal Conservation

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Invasive predators threaten biodiversity worldwide, and generalist invasive predators are often more successful due to their broad diets. Predation patterns can be influenced by prey abundance, prey preference, and climate, and understanding these relationships is integral to conserving native prey species. We examined stomach contents of 2882 feral cats Felis catus from San Clemente Island, California, to assess how their diets varied annually and seasonally, and how precipitation and prey abundance influenced predation patterns. Rodents were found in 95% (n = 2589) of stomachs containing prey. The endemic San Clemente deer mouse Peromyscus maniculatus clementis was the most prevalent prey species and was found in 85% (n = 2589) of stomachs containing prey. Consumption of rodents, lizards, and birds varied annually. In years following dry winters, consumption of rodents decreased and consumption of lizards increased. This had a particularly strong effect on endemic night lizards Xantusia riversiana reticulata with 20.4% (n = 1952) of non-empty cat stomachs containing night lizards following normal years, and 43.7% (n = 602) following dry years. Consumption of rodents peaked in fall, while consumption of lizards and birds peaked in spring. Using rodenticide removed from bait stations as an index of rodent abundance, we found a positive correlation between bait removal and the number of rodents consumed by cats, and a negative correlation between bait removal and the number of lizards consumed by cats. These results suggest that feral cats use rodents as primary prey and lizards as secondary prey, particularly during droughts when rodent abundance is low. Understanding how weather patterns affect invasive species predation patterns will help conservation biologists predict and manage for the effects of invasive species as climate change continues. Furthermore, identifying and quantifying diet pattern seasonality can help managers identify times when sensitive species are vulnerable and plan interventions accordingly.Animal Conservation 23 (2020) 60-71 ª

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Section: Discussionmentioning

confidence: 53%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Precipitation and prey abundance influence food habits of an invasive carnivore

Parsons¹,

Bridges²,

Biteman³

et al. 2019

Animal Conservation

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Understanding extinction risk and resilience in an extremely small population facing climate and ecosystem change

2021

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San Nicolas Island (SNI) foxes historically had the highest densities of the six subspecies of Channel Island fox, four of which were listed as endangered in the 1990s. As an island species, SNI foxes are inherently vulnerable because they evolved in isolation from many potential threats, and their small range features relatively simple and degraded habitats, limiting their population size and heightening susceptibility to climate‐driven habitat changes. In the past decade, the SNI fox population has decreased by nearly half, spurring concern. Our analyses of 18 yr of trapping data suggest that both drought and density dependence contributed to this decline. Density dependence in survival acted on older individuals and its strength doubled after recent drought‐induced habitat changes. Annual precipitation was a strong driver of pup production, but density dependence moderated precipitation benefits. Using a stochastic model with island‐specific drivers of demography, we developed a risk isocline tool to predict 50‐yr quasi‐extinction risk based on population size and mortality. Predicted extinction risk for SNI foxes is currently <5% and expected to decrease. Compared to the previously listed subspecies, risk isoclines indicate the SNI subspecies is more resistant to quasi‐extinction at moderate population sizes and mortality rates, but quasi‐extinction risk does not decline as rapidly at higher population sizes or lower mortality rates. Thus, limiting human‐caused mortality and monitoring for novel threats such as exotic disease remain important. The ability of SNI foxes to increase pup production following high‐rainfall low‐density years is a key feature stabilizing their dynamics. Habitat‐ and location‐specific dynamics produce substantial portfolio effects, whereby asynchrony in growth rates stabilizes overall population numbers, and restoration efforts that increase food resources and habitat diversity will further enhance the resilience of this population. Although the SNI fox appears to be rebounding, its recent decline may foreshadow future dynamics and serves as a cautionary tale for stewards of island species facing unprecedented climatic conditions, especially those inhabiting small and less diverse systems. Finally, our analyses highlight limitations in applying risk analyses from one population to related species, or even the same species in different habitat settings.

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Predicted future range expansion of a small carnivore: swift fox in North America

Nelson,

Marneweck,

McShea

et al. 2024

Landsc Ecol

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Context Small carnivores are declining globally due to a complex suite of threats. Conservation of these species requires an understanding of their distributions and potential responses to future land-use and climate change. Objectives We modelled species-environment relationships of swift fox (Vulpes velox), a species of concern across their range. We developed spatial projections of current and future distribution to aid in conservation planning. Methods We assembled swift fox occurrence data from managers and community science sources to develop ensemble distribution models. In addition to landscape and climatic predictors, we developed a model of red fox distribution to represent effects of competition. We forecasted spatial predictions into the year 2070 under two climate change scenarios representing high (SSP 5–8.5) and low (SSP 1–2.6) emissions scenarios. Results Percent cover by grassland, mean annual precipitation, and minimum temperature of the coldest quarter were the three most important variables for swift fox distribution. Current suitable habitat for swift fox extends across 16 North American states and provinces. Future projections of swift fox distribution suggest an overall increase in area of swift fox suitable habitat under both emissions scenarios of > 56.9%, though patterns of gain and loss vary spatially. Conclusions The expansion of suitable habitat in future scenarios reflects swift fox adaptability to multiple land uses in a period following multi-organizational conservation efforts. Our spatial projections can be used in conservation planning and can serve as a case study of a small carnivore species likely to recover under future change scenarios provided that threats are addressed and landscape-scale conservation efforts continue.

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Diet patterns of island foxes on San Nicolas Island relative to feral cat removal

Cited by 22 publications

References 19 publications

Precipitation and prey abundance influence food habits of an invasive carnivore

Precipitation and prey abundance influence food habits of an invasive carnivore

Understanding extinction risk and resilience in an extremely small population facing climate and ecosystem change

Predicted future range expansion of a small carnivore: swift fox in North America

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