Australia’s feral cat population represents one of the most significant threats to the continent’s unique biodiversity. With an estimated 2.8 million feral cats roaming the Australian landscape at any given time — a figure that can swell to as many as 5.6 million during favourable conditions — these silent predators are responsible for the deaths of approximately 1.5 billion native animals every single year. From the arid deserts of central Australia to the lush rainforests of Queensland, feral cats have established themselves in virtually every habitat across the continent, leaving a trail of ecological devastation in their wake.
Origins and Spread
Domestic cats (Felis catus) first arrived on Australian shores with European settlers in the late eighteenth century. Initially brought aboard ships as pest control for rats and mice, cats quickly escaped or were released into the bush. By the mid-nineteenth century, feral cat populations had established themselves across vast swathes of the Australian mainland. Some historians suggest that cats may have arrived even earlier, possibly introduced by Malaysian trepang fishers who visited Australia’s northern coastline centuries before European colonisation.
The spread of feral cats across Australia was remarkably swift. Aided by the introduction of rabbits in the 1850s — which provided an abundant food source — feral cats expanded their range at a staggering pace. Within a few decades, they had colonised almost every corner of the continent, from offshore islands to alpine regions. Today, feral cats occupy an estimated 99.9 per cent of Australia’s land area, making them one of the most widespread invasive predators on the planet.
Physical Characteristics and Behaviour
Feral cats in Australia are typically larger and more robust than their domestic counterparts. Males can weigh up to 7 kilograms, though specimens exceeding 10 kilograms have been recorded in some regions. Their coats vary widely in colour and pattern, reflecting the diverse gene pool from which they have descended. Tabby, ginger, black, and calico patterns are all common, providing effective camouflage in a variety of Australian habitats.
These cats are primarily nocturnal hunters, although they will also hunt during the day, particularly at dawn and dusk. They are solitary animals, with males maintaining large home ranges that can span up to 22 square kilometres in arid environments. Feral cats are opportunistic predators with exceptional hunting skills. Their keen eyesight, acute hearing, and silent stalking ability make them devastatingly effective hunters of small mammals, birds, reptiles, and insects.
A single feral cat can kill between 5 and 30 animals per day, depending on the availability of prey and the cat’s size and hunting efficiency. Research conducted by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) has demonstrated that feral cats in arid Australia rely heavily on small native mammals, which often have no evolutionary experience with such efficient mammalian predators.
Impact on Native Wildlife
The toll that feral cats take on Australian wildlife is nothing short of catastrophic. According to research published by the Threatened Species Recovery Hub, feral cats kill approximately 815 million mammals, 377 million birds, and 647 million reptiles each year across the continent. These figures place feral cats among the leading causes of wildlife decline and species extinction in Australia.
Feral cats have been implicated in the extinction of at least 20 native mammal species since European settlement, and they continue to threaten the survival of more than 100 species listed as threatened under Australia’s Environment Protection and Biodiversity Conservation Act 1999. Among the most vulnerable species are small to medium-sized ground-dwelling mammals such as the bilby, numbat, western quoll, and several species of bandicoot and rock-wallaby.
The impact extends well beyond mammals. Ground-nesting birds such as the plains-wanderer and the malleefowl are particularly susceptible to cat predation, as are numerous species of native reptiles, including geckos, skinks, and small dragons. On offshore islands, where native species have evolved in the absence of mammalian predators, the introduction of even a small number of cats can have devastating consequences for entire populations.
Management and Control Strategies
Managing feral cats across a continent as vast as Australia presents enormous logistical and ethical challenges. The Australian Government has invested significantly in feral cat control, with the Threatened Species Strategy setting an ambitious target to cull two million feral cats by 2020. A range of control methods are employed, including trapping, shooting, baiting, and the construction of predator-proof fences.
One of the most promising developments in feral cat control has been the Eradicat and Curiosity baits. Eradicat, developed in Western Australia, is a sausage-style bait containing the toxin 1080 (sodium fluoroacetate), a naturally occurring compound found in many Australian native plants. Because Australian native animals have evolved a tolerance to 1080, the bait is selectively lethal to introduced predators such as cats and foxes while posing a relatively low risk to native wildlife.
Curiosity, developed by the CSIRO in partnership with Scientec Research, represents the next generation of cat baiting technology. Unlike Eradicat, Curiosity uses para-aminopropiophenone (PAPP) as its active ingredient and is designed specifically to target feral cats through their natural curiosity and hunting behaviour.
Predator-proof fencing has also emerged as a critical tool in protecting vulnerable native species from feral cats. Sanctuaries such as those managed by the Australian Government Department of Climate Change, Energy, the Environment and Water provide predator-free havens where threatened species can breed and recover. These fenced areas now protect some of the last remaining populations of species such as the greater bilby and the bridled nailtail wallaby.
The Role of Pet Cats
While feral cats receive much of the attention, domestic pet cats also contribute significantly to wildlife mortality in Australia. Research estimates that pet cats kill approximately 390 million animals per year across the country. Many local governments have responded by introducing cat curfews or containment laws, requiring pet cats to be kept indoors or within enclosed outdoor areas, particularly during the night.
Responsible pet ownership is a crucial component of any comprehensive strategy to reduce the impact of cats on native wildlife. Keeping cats indoors, desexing pets, and microchipping are all simple but effective measures that can significantly reduce the number of cats that enter the feral population. Organisations such as the RSPCA Australia actively promote responsible cat ownership and support policies that protect both cats and wildlife.
Looking to the Future
The challenge of managing feral cats in Australia is unlikely to be resolved quickly or easily. However, ongoing research, improved control technologies, and greater community awareness are all contributing to a more coordinated and effective response. Innovations in genetic technologies, including the potential development of gene-drive approaches, may offer new possibilities for controlling feral cat populations in the decades ahead.
The establishment of a national network of predator-free safe havens, combined with landscape-scale control programs, offers the best hope for protecting Australia’s most vulnerable species from the relentless pressure of feral cat predation. With continued investment and community support, it is possible to turn the tide against these silent predators and secure a future for Australia’s extraordinary native wildlife.
Every Australian has a role to play in addressing the feral cat crisis. Whether through supporting local conservation groups, advocating for stronger cat management legislation, or simply keeping pet cats safely contained, individual actions can collectively make a significant difference in protecting the unique animals that call this continent home.