Pacific Conservation Biology Pacific Conservation Biology Society
A journal dedicated to conservation and wildlife management in the Pacific region.
RESEARCH ARTICLE

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

Brian L. Cypher A E , Erica C. Kelly A , Francesca J. Ferrara B , Charles A. Drost C , Tory L. Westall A and Brian R. Hudgens D

A Endangered Species Recovery Program, California State University – Stanislaus, One University Circle, Turlock, CA 95382, USA.

B Environmental Planning and Conservation Branch, Naval Base Ventura County, 311 Main Road, Point Mugu, CA 93042, USA.

C US Geological Survey, Southwest Biological Science Center, 2255 N. Gemini Drive, Flagstaff, AZ 86001, USA.

D Institute for Wildlife Studies, PO Box 1104, Arcata, CA 95518, USA.

E Corresponding author. Email: bcypher@esrp.csustan.edu

Pacific Conservation Biology - https://doi.org/10.1071/PC16037
Submitted: 13 September 2016  Accepted: 1 January 2017   Published online: 3 February 2017

Abstract

Island foxes (Urocyon littoralis) are a species of conservation concern that occur on six of the Channel Islands off the coast of southern California. We analysed island fox diet on San Nicolas Island during 2006–12 to assess the influence of the removal of feral cats (Felis catus) on the food use by foxes. Our objective was to determine whether fox diet patterns shifted in response to the cat removal conducted during 2009–10, thus indicating that cats were competing with foxes for food items. We also examined the influence of annual precipitation patterns and fox abundance on fox diet. On the basis of an analysis of 1975 fox scats, use of vertebrate prey – deer mice (Peromyscus maniculatus), birds, and lizards – increased significantly during and after the complete removal of cats (n = 66) from the island. Deer mouse abundance increased markedly during and after cat removal and use of mice by foxes was significantly related to mouse abundance. The increase in mice and shift in item use by the foxes was consistent with a reduction in exploitative competition associated with the cat removal. However, fox abundance declined markedly coincident with the removal of cats and deer mouse abundance was negatively related to fox numbers. Also, annual precipitation increased markedly during and after cat removal and deer mouse abundance closely tracked precipitation. Thus, our results indicate that other confounding factors, particularly precipitation, may have had a greater influence on fox diet patterns.

Additional keywords: deer mice, exploitative competition, feral cats, foraging ecology, precipitation


References

Atkinson, I. (1989). Introduced animals and extinctions. In ‘Conservation for the Twenty-First Century’. (Eds D. Western and M. Pearl.) pp. 54–69. (Oxford University Press: New York.)

Bock, C. E., and Bock, J. H. (1999). Response of winter birds to drought and short-duration grazing in southeastern Arizona. Conservation Biology 13, 1117–1123.
Response of winter birds to drought and short-duration grazing in southeastern Arizona.CrossRef | open url image1

Bonnaud, E., Medina, F. M., Vidal, E., Nogales, M., Tershy, B., Donlan, C. J., and Corre, M. (2011). The diet of feral cats on islands: a review and a call for more studies. Biological Invasions 13, 581–603.
The diet of feral cats on islands: a review and a call for more studies.CrossRef | open url image1

Brower, J. E., and Zar, J. H. (1984). ‘Field and Laboratory Methods for General Ecology.’ (Wm. C. Brown Publishers: Dubuque, IA.)

Coonan, T. J., Schwemm, C. A., and Garcelon, D. K. (2010). ‘Decline and Recovery of the Island Fox: A Case Study for Population Recovery.’ (Cambridge University Press: New York.)

Coonan, T., Ralls, K., Hudgens, B., Cypher, B., and Boser, C. (2013). Urocyon littoralis. In ‘The IUCN Red List of Threatened Species (Version 2014.1.)’. Available at: http://iucnredlist.org/details/22781/0/ [accessed 1 June 2016].

Courchamp, F., Chapuis, J. L., and Pascal, M. (2003). Mammal invaders on islands: impact, control and control impact. Biological Reviews of the Cambridge Philosophical Society 78, 347–383.
Mammal invaders on islands: impact, control and control impact.CrossRef | open url image1

Cypher, B. L., Warrick, G. D., Otten, M. R. M., O’Farrell, T. P., Berry, W. H., Harris, C. E., Kato, T. T., McCue, P. M., Scrivner, J. H., and Zoellick, B. W. (2000). Population dynamics of San Joaquin kit foxes at the Naval Petroleum Reserves in California. Wildlife Monographs 45, 1–43. open url image1

Cypher, B. L., Madrid, A. Y., Van Horn Job, C. L., Kelly, E. C., Harrison, S. W. R., and Westall, T. L. (2014). Multi-population comparison of resource exploitation by island foxes: implications for conservation. Global Ecology and Conservation 2, 255–266.
Multi-population comparison of resource exploitation by island foxes: implications for conservation.CrossRef | open url image1

Doherty, T. S., Glen, A. S., Nimmo, D. G., Ritchie, E. G., and Dickman, C. R. (2016). Invasive predators and global biodiversity loss. Proceedings of the National Academy of Sciences of the United States of America 113, 11261–11265.
Invasive predators and global biodiversity loss.CrossRef | 1:CAS:528:DC%2BC28XhsFWls7bN&md5=946360bc8e8373745ccc27b28db3a426CAS | open url image1

Drost, C. (2014). Deer mouse populations on San Nicolas Island, before and after removal of non-native cats. Final report, Naval Base Ventura County, Point Mugu, CA.

Drost, C. A., and Fellers, G. M. (1991). Density cycles in an island population of deer mice, Peromyscus maniculatus (Wagner). Oikos 60, 351–354.
Density cycles in an island population of deer mice, Peromyscus maniculatus (Wagner).CrossRef | open url image1

Glass, B. P. (1981). ‘Key to the Skulls of North American Mammals.’ (Oklahoma State University: Stillwater, OK.)

Guttilla, D. A. (2007). Effects of sterilization on movement, home range behavior, and habitat use of feral cats on Santa Catalina Island, California. M.S. Thesis, California State University, Fullerton, CA.

Hanson, C. C., Jolley, W. J., Smith, G., Garcelon, D. K., Keitt, B. S., Little, A. E., and Campbell, K. J. (2015). Feral cat eradication in the presence of endemic San Nicolas Island foxes. Biological Invasions 17, 977–986.
Feral cat eradication in the presence of endemic San Nicolas Island foxes.CrossRef | open url image1

Hudgens, B. R., and Garcelon, D. K. (2014). Island fox monitoring and demography on San Nicolas Island – 2013. Final report, Institute for Wildlife Studies, Arcata, CA.

Island Conservation (2007). San Nicolas Island seabird restoration: project plan for cat eradication. Final report, Santa Cruz, CA.

Junak, S. (2008). ‘A flora of San Nicolas Island.’ (Santa Barbara Botanic Garden: Santa Barbara, CA.)

Kovach, S. D., and Dow, R. J. (1981a). Ecology of the feral cat on San Nicolas Island, 1980. Technical Memorandum TM-81-29, Pacific Missile Test Center, Point Mugu, CA.

Kovach, S. D., and Dow, R. J. (1981b). Status and ecology of the island fox on San Nicolas Island, 1980. Technical Memorandum TM-81-28, Pacific Missile Test Center, Point Mugu, CA.

Kovach, S. D., and Dow, R. J. (1985). Island fox research, San Nicolas Island, Ventura County, California: 1984. Annual report, California Department of Fish and Game, Sacramento, CA.

Laughrin, L. L. (1973). The island fox. Environment Southwest 458, 6–9. open url image1

Laughrin, L. L. (1980). Populations and status of the island fox. In ‘The California Islands: Proceedings of a Multidisciplinary Symposium’. (Ed. D. M. Power.) pp. 745–750. (Santa Barbara Museum of Natural History: Santa Barbara, CA.)

Lepczyk, C. A., Lohr, C. A., and Duffy, D. C. (2015). A review of cat behavior in relation to disease risk and management options. Applied Animal Behaviour Science 173, 29–39.
A review of cat behavior in relation to disease risk and management options.CrossRef | open url image1

Lonquich, P. D. (1979). Ecology of feral house cats (Felis domestica) on Santa Catalina Island, California. M.S. Thesis, California State University, Northridge, CA.

Luis, A. D., Douglass, R. J., Mills, J. N., and Bjørnstad, O. N. (2010). The effect of seasonality, density and climate on the population dynamics of Montana deer mice, important reservoir hosts for Sin Nombre hantavirus. Journal of Animal Ecology 79, 462–470.
The effect of seasonality, density and climate on the population dynamics of Montana deer mice, important reservoir hosts for Sin Nombre hantavirus.CrossRef | open url image1

Maron, J. L., Pearson, D. E., and Fletcher, R. J. (2010). Counterintuitive effects of large-scale predator removal on a midlatitude rodent community. Ecology 91, 3719–3728.
Counterintuitive effects of large-scale predator removal on a midlatitude rodent community.CrossRef | open url image1

Medina, F. M., Bonnaud, E., Vidal, E., Tershy, B. R., Zavaleta, E. S., Josh Donlan, C., Keitt, B. S., Corre, M., Horwath, S. V., and Nogales, M. (2011). A global review of the impacts of invasive cats on island endangered vertebrates. Global Change Biology 17, 3503–3510.
A global review of the impacts of invasive cats on island endangered vertebrates.CrossRef | open url image1

Mills, J. N., Ksiazek, T. G., Peters, C. J., and Childs, J. E. (1999). Long-term studies of hantavirus reservoir populations in the southwestern United States: a synthesis. Emerging Infectious Diseases 5, 135–142.
Long-term studies of hantavirus reservoir populations in the southwestern United States: a synthesis.CrossRef | 1:STN:280:DyaK1M7otFGhsA%3D%3D&md5=7c61d82690949905d31105741b65e48fCAS | open url image1

Moore, C. M., and Collins, P. W. (1995). Urocyon littoralis. Mammalian Species 489, 1–7.
Urocyon littoralis.CrossRef | open url image1

Moore, T. D., Spence, L. E., and Dugnolle, C. E. (1974). ‘Identification of the Dorsal Hairs of Some Animals of Wyoming.’ (Wyoming Game and Fish Department: Cheyenne, WY.)

Otis, D. L., Burnham, K. P., White, G. C., and Anderson, D. R. (1978). Statistical-inference from capture data on closed animal populations. Wildlife Monographs 62, 3–135. open url image1

Phillips, R. B., Winchell, C. S., and Schmidt, R. H. (2007). Dietary overlap of an alien and native carnivore on San Clemente Island, California. Journal of Mammalogy 88, 173–180.
Dietary overlap of an alien and native carnivore on San Clemente Island, California.CrossRef | open url image1

Pollock, K. H. (1982). A capture–recapture design robust to unequal probability of capture. Journal of Wildlife Management 46, 752–757.
A capture–recapture design robust to unequal probability of capture.CrossRef | open url image1

Roemer, G. W., Coonan, T. J., Garcelon, D. K., Bascompte, J., and Laughrin, L. (2001). Feral pigs facilitate hyperpredation by golden eagles and indirectly cause the decline of the island fox. Animal Conservation 4, 307–318.
Feral pigs facilitate hyperpredation by golden eagles and indirectly cause the decline of the island fox.CrossRef | open url image1

Roest, A. I. (1986). ‘A Key-Guide to Mammal Skulls and Lower Jaws.’ (Mad River Press: Eureka, CA.)

Schoenherr, A. A., Feldmeth, C. R., and Emerson, M. J. (1999). ‘Natural History of the Islands of California.’ (University of California Press: Berkeley, CA.)

Simberloff, D. (1995). Why do introduced species appear to devastate islands more than mainland areas? Pacific Science 49, 87–97. open url image1

Timm, S. F., Munson, L., Summers, B. A., Terio, K. A., Dubovi, E. J., Rupprecht, C. E., Kapil, A., and Garcelon, D. K. (2009). A suspected canine distemper epidemic as the cause of a catastrophic decline in the Santa Catalina Island foxes (Urocyon littoralis catalinae). Journal of Wildlife Diseases 45, 333–343.
A suspected canine distemper epidemic as the cause of a catastrophic decline in the Santa Catalina Island foxes (Urocyon littoralis catalinae).CrossRef | open url image1

USFWS (2009). Final Environmental Assessment for the restoration of San Nicolas Island’s seabirds and protection of other native fauna by removing feral cats. US Fish and Wildlife Service, Sacramento, CA.

USFWS (2015). Recovery plan for four subspecies of island fox (Urocyon littoralis). US Fish and Wildlife Service, Ventura, CA.

US Navy (2005). Integrated natural resources management plan San Nicolas Island. CA (Edinburgh), 2006–2010 [Naval Base Ventura County, Point Mugu, CA].

Vitousek, P. M., D’Antonio, C. M., Loope, L. L., Reimanke, M., and Westbrooks, R. (1997). Introduced species: a significant component of human-caused global change. New Zealand Journal of Ecology 21, 1–16. open url image1

White, G. C., and Burnham, K. P. (1999). Program MARK: Survival estimation from populations of marked animals. Bird Study 46, S120–S138.
Program MARK: Survival estimation from populations of marked animals.CrossRef | open url image1

White, G. C., Anderson, D. R., Burnham, K. P., and Otis, D. L. (1982). Capture–recapture and removal methods for sampling closed populations. Rep LA-8787-NERP, Los Alamos National Lab, Los Alamos, NM.

White, P. J., Ralls, K., and Vanderbilt-White, C. A. (1996). Overlap in habitat and food use between coyotes and San Joaquin kit foxes. The Southwestern Naturalist 40, 342–349. open url image1

Whitford, W. G., and Creusere, F. M. (1977). Seasonal and yearly fluctuations in Chihuahuan Desert lizard communities. Herpetologica 33, 54–65. open url image1

Wilcove, D. S., Rothstein, D., Dubow, J., Phillips, A., and Losos, E. (1998). Quantifying threats to imperiled species in the United States. Bioscience 48, 607–615.
Quantifying threats to imperiled species in the United States.CrossRef | open url image1

Young, J. A., and Young, C. G. (1992). ‘Seeds of Woody Plants in North America.’ (Dioscorides Press: Portland, OR.)

Zar, J. H. (1984). ‘Biostatistical Analysis.’ 2nd edn. (Prentice-Hall: Englewood Cliffs, NJ.)



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