The threat of feral cats

We are certain that feral cats have caused the decline and extinction of animals on islands. We understand less about the nature and extent of the threat posed by feral cats on the mainland. In some areas of Australia, such as the tropics, Kangaroo Island and Tasmania, feral cats have been around for more than a century and don't appear to have contributed to extinctions of any native animals.

In NSW:

• The circumstantial evidence is mounting that 'predation' (killing and eating prey) by feral cats is having a significant impact on ground birds and small native mammals, particularly in the arid western regions of the state.
• Feral cats have also thwarted attempts to re-introduce threatened species to areas where they have become extinct. The cats have simply hunted and killed the newly released animals.

Direct evidence of the impact of feral cat predation is difficult to collect, as feral cats tend to be shy and elusive. It is also difficult to separate out the effect of feral cats from other factors that may lead to the decline of a native species, such as competition from other introduced animals and clearing of habitat.

Several factors can operate at once, and different factors can interact with each other. For example, clearing and fragmentation of habitat can lead to a reduced population of a native species. This native species then becomes more susceptible to disease or to the effects of a predator. Where a population has become very small and isolated, just one or two individual cats can have a devastating impact.

Concerns about the impact have led the NSW Scientific Committee to list predation by feral cats as a key threatening process under the Threatened Species Conservation Act 1995.

Although feral cats are the same species as domestic cats, only predation by feral cats has been identified as a key threatening process. Feral cat populations are mostly located far from human habitation, and do not depend on stray domestic cats to keep up their numbers. A relatively small number of domestic cats may become strays, but this does not significantly add to the feral cat population.