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Ecology, management and conservation in natural and modified habitats
RESEARCH ARTICLE

Evidence of significantly higher island feral cat abundance compared with the adjacent mainland

Patrick L. Taggart https://orcid.org/0000-0001-9523-0463 A H , Bronwyn A. Fancourt https://orcid.org/0000-0003-2969-1530 B C , Andrew J. Bengsen D , David E. Peacock https://orcid.org/0000-0003-2891-8238 A E , Patrick Hodgens F , John L. Read G , Milton M. McAllister A * and Charles G. B. Caraguel A *
+ Author Affiliations
- Author Affiliations

A School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, SA 5371, Australia.

B Pest Animal Research Centre, Biosecurity Queensland, Department of Agriculture and Fisheries, Toowoomba, Qld 4350, Australia.

C School of Environmental and Rural Science, University of New England, Armidale, NSW 2350, Australia.

D Vertebrate Pest Research Unit, Department of Primary Industries, Orange, NSW 2800, Australia.

E Biosecurity South Australia, Adelaide, SA 5001, Australia.

F Terrain Ecology, PO Box 966, Kingscote, SA 5223, Australia.

G School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, SA 5005, Australia.

H Corresponding author. Email: patrick.taggart@adelaide.edu.au

Wildlife Research 46(5) 378-385 https://doi.org/10.1071/WR18118
Submitted: 18 July 2018  Accepted: 31 March 2019   Published: 4 July 2019

Abstract

Context: Feral cats (Felis catus) impact the health and welfare of wildlife, livestock and humans worldwide. They are particularly damaging where they have been introduced into island countries such as Australia and New Zealand, where native prey species evolved without feline predators. Kangaroo Island, in South Australia, is Australia’s third largest island and supports several threatened and endemic species. Cat densities on Kangaroo Island are thought to be greater than those on the adjacent South Australian mainland, based on one cat density estimate on the island that is higher than most estimates from the mainland. The prevalence of cat-borne disease in cats and sheep is also higher on Kangaroo Island than the mainland, suggesting higher cat densities. A recent continental-scale spatial model of cat density predicted that cat density on Kangaroo Island should be about double that of the adjacent mainland. However, although cats are believed to have severe impacts on some native species on the island, other species that are generally considered vulnerable to cat predation have relatively secure populations on the island compared with the mainland.

Aims: The present study aimed to compare feral cat abundance between Kangaroo Island and the adjacent South Australian mainland using simultaneous standardised methods. Based on previous findings, we predicted that the relative abundance of feral cats on Kangaroo Island would be approximately double that on the South Australian mainland.

Methods: Standardised camera trap surveys were used to simultaneously estimate the relative abundance of feral cats on Kangaroo Island and the adjacent South Australian mainland. Survey data were analysed using the Royle–Nichols abundance-induced heterogeneity model to estimate feral cat relative abundance at each site.

Key results: Cat abundance on the island was estimated to be over 10 times greater than that on the adjacent mainland.

Conclusions: Consistent with predictions, cat abundance on the island was greater than on the adjacent mainland. However, the magnitude of this difference was much greater than expected.

Implications: The findings show that the actual densities of cats at local sites can vary substantially from predictions generated by continental-scale models. The study also demonstrates the value of estimating abundance or density simultaneously across sites using standardised methods.

Additional keywords: feline, Felis catus, insular, invasive predator, invasive species, pest management.


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