Movement patterns of feral predators in an arid environment – implications for control through poison baiting
K. E. Moseby A B C , J. Stott A and H. Crisp A BA Arid Recovery, PO Box 150, Roxby Downs, SA 5725, Australia.
B School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, SA 5005, Australia.
C Corresponding author. Email: katherine.moseby@adelaide.edu.au
Wildlife Research 36(5) 422-435 https://doi.org/10.1071/WR08098
Submitted: 19 June 2008 Accepted: 23 April 2009 Published: 21 July 2009
Abstract
Control of introduced predators is critical to both protection and successful reintroduction of threatened prey species. Efficiency of control is improved if it takes into account habitat use, home range and the activity patterns of the predator. These characteristics were studied in feral cats (Felis catus) and red foxes (Vulpes vulpes) in arid South Australia, and results are used to suggest improvements in control methods. In addition, mortality and movement patterns of cats before and after a poison-baiting event were compared. Thirteen cats and four foxes were successfully fitted with GPS data-logger radio-collars and tracked 4-hourly for several months. High intra-specific variation in cat home-range size was recorded, with 95% minimum convex polygon (MCP) home ranges varying from 0.5 km2 to 132 km2. Cat home-range size was not significantly different from that of foxes, nor was there a significant difference related to sex or age. Cats preferred habitat types that support thicker vegetation cover, including creeklines and sand dunes, whereas foxes preferred sand dunes. Cats used temporary focal points (areas used intensively over short time periods and then vacated) for periods of up to 2 weeks and continually moved throughout their home range. Aerial baiting at a density of 10 baits per km2 was ineffective for cats because similar high mortality rates were recorded for cats in both baited and unbaited areas. Mortality was highest in young male cats. Long-range movements of up to 45 km in 2 days were recorded in male feral cats and movement into the baited zone occurred within 2 days of baiting. Movement patterns of radio-collared animals and inferred bait detection distances were used to suggest optimum baiting densities of ~30 baits per km2 for feral cats and 5 per km2 for foxes. Feral cats exhibited much higher intra-specific variation in activity patterns and home-range size than did foxes, rendering them a potentially difficult species to control by a single method. Control of cats and foxes in arid Australia should target habitats with thick vegetation cover and aerial baiting should ideally occur over areas of several thousand square kilometres because of large home ranges and long-range movements increasing the chance of fast reinvasion. The use of temporary focal points suggested that it may take several days or even weeks for a cat to encounter a fixed trap site within their home range, whereas foxes should encounter them more quickly as they move further each day although they have a similar home-range size. Because of high intra-specific variability in activity patterns and home-range size, control of feral cats in inland Australia may be best achieved through a combination of control techniques.
Acknowledgements
Arid Recovery is a joint initiative between BHP Billiton, The University of Adelaide, SA Department for Environment and Heritage and the local Friends of Arid Recovery. Funding was also provided by the South Australian Arid Lands Natural Resource Management Board through the Federal Government Natural Heritage Trust program. This study was conducted under animal ethics permits 14-2002 and 9-2006 through the Wildlife Ethics Committee (SA Department for Environment and Heritage). We thank members of the Friends of Arid Recovery who assisted in the field and the local veterinary clinic for assisting with training in the use of anaesthetics. Gratitude also goes to Phil Goldsworthy and the Roxby Downs Aeroclub for assisting with radio-tracking and we are indebted to Ross Cunningham for his statistical support. John Read and the three referees provided insightful and useful comments on the manuscript.
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