Cats in Australia

Feral cats are one of the major invasive species in Australia and have been linked to the decline and extinction of various native animals. They have been shown to cause a significant impact on ground-nesting birds and small native mammals.[8] Feral cats have also hampered attempts to reintroduce threatened species back into areas where they have become extinct, as the cats quickly kill the newly released animals.[9] Many Australian environmentalists argue that the feral cat has been an ecological disaster in Australia, inhabiting most ecosystems except dense rainforest, and being implicated in the extinction of several marsupial and placental mammal species.[10][11]

A field experiment conducted in Heirisson Prong (Western Australia) compared small mammal populations in areas cleared of both foxes and cats, of foxes only, and a control plot. Researchers found the first solid evidence that predation by feral cats can cause a decline in native mammals. It also indicates that cat predation is especially severe when fox numbers have been reduced.[12] Cats may play a role in Australia's altered ecosystems; with foxes they may be controlling introduced rabbits, particularly in arid areas, which themselves cause ecological damage. Cats are believed to have been a factor in the extinction of the only mainland bird species to be lost since European settlement, the paradise parrot.[13] Cats in Australia have no natural predators except dingoes and wedge-tailed eagles, and as a result, they are apex predators where neither the dingo nor the eagle exists.[14] Also, dingos do not appear to affect the activity of cats.[15]

Australian folklore holds that some feral cats in Australia have grown so large as to cause inexperienced observers to claim sightings of other species such as cougars. While this rarely occurs in reality, large specimens are occasionally found: in 2005, an enormous feline was shot in the Gippsland area of Victoria.[16] Subsequent DNA test showed it to be a feral cat.[17]

Some researchers argue that feral cats may suppress and control the number of rats and rabbits, and cat eradication may damage native species indirectly.[18][19]

The cost to the national economy (mainly borne by farmers) over the 60 years up to 2021 is estimated to be nearly A$19 billion, with most of the cost spent on population control. This cost way outstrips the next most expensive invasive species in Australia, with the rabbit coming in at nearly A$2 billion.[20]

Pintupi, Nyirripi and other Western Desert peoples in Western Australia and Northern Territory have been hunting cats to use as a food source and for bush medicine for decades, but in 2015 they were also participating in a program with ecologists to help monitor and reduce cat predation on threatened species.[21]

Since 2016, a program on Kangaroo Island aims to fully eradicate the island's feral cat population, estimated at between 3000 and 5000, by 2030.[22][23] The 2019-2020 bushfires have complicated the eradication efforts, as the gradual regrowth of the burnt brush creates favourable conditions for cat breeding and makes them more difficult to hunt.[24] By the end of 2021, at least 850 cats had been removed from the burnt area at the western end of the island using state-of-the-art technology with traps and cameras. In addition, an exclusion fence had been built on private property around some of the burnt land, helping to protect the populations of Kangaroo Island dunnart and southern brown bandicoot.[25]