A feral cat is a cat that lives outdoors and has had little or no human contact. They do not allow themselves to be handled or touched by humans, and will run away if they are able.
In a series of recent studies, John Woinarski concluded that the Australian feral cat population fluctuates between 1.4 to 5.6 million; that areas without cats comprise <0.5% of Australia; that cats kill more than 1 million birds, more than 1 million reptiles, and more than 1 million mammals in Australia every day. Feral cats are presumed to be responsible for the extinction of about 20 native Australian species and for putting many more on the threatened species list. They are particularly damaging to populations of critical weight range marsupials – meaning any animal that is less than 3kg. (Guardian)