A new report titled ‘Enumerating a continental-scale threat: How many feral cats are in Australia?’ has given the most up-to-date estimate of the number of feral cats living in Australia. Published in the journal Biological Conservation, the report is co-authored by 41 researchers and provides a creditable estimation of the fluctuating feral cat population based on dry and wet conditions across the nation.
The abstract of the report details that feral cats (Felis catus) have devastated wildlife globally. In Australia, feral cats are implicated in most recent mammal extinctions and continue to threaten native species. Cat control is a high-profile priority for Australian policy, research and management. To develop the evidence base to support this priority, researchers first reviewed information on cat presence/absence on Australian islands and mainland cat-proof enclosures. It was found that cats occur across 99.8 per cent of Australia’s land area.
Next, the researchers collated 91 site-based feral cat density estimates in Australia and examined the influence of environmental and geographic influences on density. Researchers extrapolated from that analysis to then estimate that the feral cat population in natural environments fluctuates between 1.4 million (95 per cent confidence interval: 1-2.3 million) after continent-wide droughts, to 5.6 million (95 per cent CI: 2.5-11 million) after extensive wet periods. Researchers estimated another 0.7 million feral cats occur in Australia’s highly modified environments (urban areas, rubbish dumps and intensive farms). Feral cat densities are higher on small islands than the mainland, but similar inside and outside conservation land. Mainland cats reach highest densities in arid/semi-arid areas after wet periods. Regional variation in cat densities corresponds closely with attrition rates for native mammal fauna.
The overall population estimate for Australia’s feral cats (in natural and highly modified environments) fluctuates between 2.1 and 6.3 million, which is less than previous estimates. Australian feral cat densities are lower than those reported for North America and Europe. Nevertheless, cats severely impact Australian fauna, reflecting the sensitivity of Australia’s native species to cats and reinforcing that policy, research and management to reduce their impacts is critical.