Applying home-range and landscape-use data to design effective feral-cat control programs

Context. Effective feral-cat (Felis silvestris catus) management requires a sound understanding of the ways cats use their environment. Key characteristics of landscape use by cats vary widely among different regions and different conditions. Aims. The present study aimed to describe the most important characteristics of landscape use by feral cats on a large, human-populated island, and to use this information to guide the development of feral-cat management programs. Methods. We used GPS tracking collars to record the movements of 13 feral cats at two sites on Kangaroo Island, South Australia, for between 20 and 106 days. We described home-range extents by using local convex hulls, and derived management suggestions from examination of home-range and movement data. Key results. Median feral-cat home range was 5.11 km(2), and this did not differ between sexes or sites. Cats at a fragmented pastoral site tended to favour woody vegetation over open paddocks, but habitat preferences were less clear at a bushland site. Cats that preferentially used treelines at the pastoral site were almost twice as likely to be recorded close to a tree-line junction as expected. Conclusions. Control programs for feral cats on Kangaroo Island should deploy control devices at a density no less than 1.7 devices km(-2). Spatial coverage should be as large as practicable or repeated frequently. Infrequent programs covering small areas can be expected only to provide short-term reductions in cat abundance. Implications. The information gained from the present study will contribute to the development of strategic sustained management plans for feral cats on Kangaroo Island. The principles from which we inferred management guidelines are applicable to other regions and species.