Exotic Animals - Predators
The Feral Cat- Felis catus
Feral cats have been in Australia since European settlement. They live independently of humans and are found in all habitats ranging from rainforest to desert throughout the Northern Territory. Expansion of their distribution in arid regions has been facilitated by their ability to obtain most of their moisture requirements from the live prey they consume.
We do not know how many feral cats are in the Northern Territory. Feral cats are secretive, cryptic, largely nocturnal and hard to catch which makes it difficult to monitor populations, especially over large areas. Available data indicate that feral cat populations fluctuate markedly in time and space.
Densities can be high in some areas when conditions are favourable. During 1994, for example, the density of feral cats on the Barkly Tableland during an eruption of the Long-haired Rat, Rattus villosissimus, was estimated at 6.3/km2. In arid areas population densities of about 0.2/km2 are more typical.
Male feral cats in the mulga woodlands of central Australia live in large territories approximately 2210 ha in size. However, in the tropics and in areas with rabbits, home ranges are likely to be much smaller.
Feral cats feed on a wide variety of invertebrates, reptiles, birds and mammals, including animals up to their own body mass in size.
The protozoan Toxoplasma gondii is an important pathogen of native fauna and humans that is carried by cats. In non-specific hosts, T. gondii can cause poor co-ordination, blindness, lethargy and often death. During 1994, toxoplasmosis cost two human lives on the Tiwi Islands. Antibodies and other indications of infection have been recorded in at least 30 species of native mammals from throughout Australia and several bird species.
Whether through predation, disease or competition, feral cats have undoubtedly played a role in the demise and extinction of native fauna, particularly in central Australia. A reintroduction programme for the Rufous Hare-wallaby or Mala (Lagorchestes hirsutus) in the Tanami Desert during the 1980s was unsuccessful due to predation by feral cats.
More recently, predation by feral cats has hampered attempts to reintroduce species like the Burrowing Bettong (Bettongia lesueur), Golden Bandicoot (Isoodon auratus) and Numbat (Myrmecobius fasciatus) in Western Australia.
The management of feral cats is a difficult and often emotive issue. Although they are susceptible to 1080 poison, feral cats do not readily accept baits unless they are nutritionally stressed. This makes broadscale control difficult to achieve under most circumstances.
