Feral cats are an invasive species in Australia. Because they are not native to Australia and were only introduced by European colonists as pets in the early 1800s, native Australian animals did not co-evolve with them. [1] As of 2016, [update] some 3.8 million domestic cats and up to 6.3 million feral cats continue to live in Australia. [2] [3] [ needs update ]
The Invasive Species Council has estimated that each year domestic and feral cats in Australia kill 1,067 million mammals, 399 million birds, 609 million reptiles, 93 million frogs, and 1.8 billion invertebrates. [4] As one of the most ecologically damaging and the most costly invasive species in Australia, predation by both domestic and feral cats has played a role in the extinction of many of Australia's indigenous animals. For instance, cats are found to have significantly contributed to the extinction of at least 22 endemic Australian mammals since the arrival of Europeans. [5]
For biosecurity reasons, any cats that are imported into Australia must meet conditions set by the Department of Agriculture, Fisheries and Forestry.
Historical records date the introduction of cats by the first settlers in 1788 and that cats first became feral around Sydney by 1820. [6] In the early 1900s concern was expressed at the pervasiveness of the cat problem. [7]
Each pet cat in Australia kills an estimated 110 native animals each year; totalling up to about 80 million native birds, 67 million native mammals and 83 million native reptiles being killed by them annually. [8]
Almost 30% of Australian households keep at least one domesticated cat. [9] [2] Domesticated cats must be microchipped in every state of Australia except Tasmania. [10] All pet cats past six months of age must be desexed in the Australian Capital Territory, Tasmania, South Australia and Western Australia. [11]
Feral cats are a major invasive species and have been linked to the decline and extinction of various native animals in Australia. They have been shown to cause a significant impact on ground-nesting birds and small native mammals. [12] A study in the 2010s estimated that each feral cat kills 740 wild animals per year. [13] 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. [14] Environmentalists conclude that feral cats have been an ecological disaster in Australia, inhabiting almost all of its ecosystems, and being implicated in the extinction of several marsupial and placental mammal species. [15] [16]
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. [17] 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. [18] 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. [19] Also, dingos do not appear to affect the activity of cats. [20]
Some researchers argue that feral cats may suppress and control the number of rats and rabbits, and cat eradication may damage native species indirectly. [21] [22]
Cats are the costliest invasive species in Australia. [23] The cost of invasive cats to the national economy is estimated to be nearly A$19 billion over the 60 years up to 2021, with most of the cost spent on population control. This cost significantly outstrips the next most costly invasive species, with rabbits in Australia coming in at nearly A$2 billion. [24]
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. [25]
Some varmint hunters of feral cats in Australia, such as Barry Green, face backlash and even death threats for the culling of the invasive species. [26] [27]
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. [28] [29] 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. [30] By the end of 2021, at least 850 cats had been removed from the burnt area at the western end of the island using grooming traps with state-of-the-art technology [31] 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. [32]
The numerous sightings of phantom cats in Australia include the Gippsland phantom cat and the Blue Mountains panther. [33]
Australian folklore holds that some feral cats have grown so large as to cause inexperienced observers to claim sightings of cougars in Western Australia. While this rarely occurs in reality, large specimens are occasionally found: in 2005, a feline was measured to be 176 cm (69 in) from the tip of its nose to the tip of its tail in the Gippsland area of Victoria. [34] Subsequent DNA tests showed it to be a feral cat. [35]
The dingo is an ancient (basal) lineage of dog found in Australia. Its taxonomic classification is debated as indicated by the variety of scientific names presently applied in different publications. It is variously considered a form of domestic dog not warranting recognition as a subspecies, a subspecies of dog or wolf, or a full species in its own right.
A feral animal or plant is one that lives in the wild but is descended from domesticated individuals. As with an introduced species, the introduction of feral animals or plants to non-native regions may disrupt ecosystems and has, in some cases, contributed to extinction of indigenous species. The removal of feral species is a major focus of island restoration.
The bridled nail-tail wallaby, also known as the bridled nail-tailed wallaby, bridled nailtail wallaby, bridled wallaby, merrin, and flashjack, is a vulnerable species of macropod. It is a small wallaby found in three isolated areas in Queensland, Australia, and whose population is declining. In early 2019 the total population of the species was estimated to be fewer than 500 mature individuals in the wild and 2285 in captivity.
A feral cat or a stray cat is an unowned domestic cat that lives outdoors and avoids human contact; it does not allow itself to be handled or touched, and usually remains hidden from humans. Feral cats may breed over dozens of generations and become an aggressive local apex predator in urban, savannah and bushland environments. Some feral cats may become more comfortable with people who regularly feed them, but even with long-term attempts at socialization, they usually remain aloof and are most active after dusk. Of the 700 million cats in the world, an estimated 480 million are feral.
Invasive species in Australia are a serious threat to the native biodiversity, and an ongoing cost to Australian agriculture. Numerous species arrived with European maritime exploration and colonisation of Australia and steadily since then. There is much ongoing debate about the potential benefits and detriments of introduced species; some experts believe that certain species, particularly megafauna such as deer, equids, bovids, and camels, may be more beneficial to Australia's ecosystems than they are detrimental, acting as replacements for extinct Australian megafauna.
The eastern barred bandicoot is a nocturnal, rabbit-sized marsupial endemic to southeastern Australia, being native to the island of Tasmania and mainland Victoria. It is one of three surviving bandicoot species in the genus Perameles. It is distinguishable from its partially-sympatric congener – the long-nosed bandicoot – via three or four dark horizontal bars found on its rump. In Tasmania, it is relatively abundant. The mainland population in Victoria is struggling and is subject to ongoing conservation endeavors.
The woylie or brush-tailed bettong is a small, critically endangered mammal native to forests and shrubland of Australia. A member of the rat-kangaroo family (Potoroidae), it moves by hopping and is active at night, digging for fungi to eat. It is also a marsupial and carries its young in a pouch. Once widespread, the woylie mostly died out from habitat loss and introduced predators such as foxes. It is currently restricted to two small areas in Western Australia. There were two subspecies: B. p. ogilbyi in the west, and the now-extinct B. p. penicillata in the southeast.
Western Shield, managed by Western Australia's Department of Parks and Wildlife, is a nature conservation program safeguarding Western Australia's animals and protecting them from extinction. The program was set up in 1996 and as of 2009 was the largest and most successful wildlife conservation program ever undertaken in Australia.
The Western barred bandicoot, also known as the Shark Bay bandicoot or the Marl, is a small species of bandicoot; now extinct across most of its former range, the western barred bandicoot only survives on offshore islands and in fenced sanctuaries on the mainland.
The rufous hare-wallaby, also known as the mala, is a small macropod found in Australia. It was formerly widely distributed across the western half of the continent, but naturally occurring populations are now confined to Bernier Island and Dorre Island Islands off Western Australia.
The Forrest's mouse, or desert short-tailed mouse, is a small species of rodent in the family Muridae. It is a widespread but sparsely distributed species found across arid and semi-arid inland Australia, commonly found in tussock grassland, chenopod shrubland, and mulga or savannah woodlands.
The greater stick-nest rat, also known as the housebuilding rat and wopilkara, is a species of rodent in the family Muridae. They are about the size of a small rabbit and construct large nests of interwoven sticks. Once widespread across southern Australia, the population was reduced after European colonisation to a remnant outpost on South Australia's Franklin Islands. The species has since been reintroduced to a series of protected and monitored areas, with varying levels of success.
Buckaringa Sanctuary is a 20 km2 nature reserve in the southern Flinders Ranges of South Australia. It is 30 km north of the town of Quorn. It is owned and managed by the Australian Wildlife Conservancy (AWC).
Red foxes pose a serious conservation problem in Australia. 2012 estimates indicate that there are more than 7.2 million red foxes, with a range extending throughout most of the continental mainland. The species became established in Australia through successive introductions, by settlers, beginning around the 1830s. Due to its rapid spread and ecological impact, it has been classified as one of the most damaging invasive species in Australia.
Seabirds include some of the most threatened taxa anywhere in the world. For example, of extant albatross species, 82% are listed as threatened, endangered, or critically endangered by the International Union for Conservation of Nature. The two leading threats to seabirds are accidental bycatch by commercial fishing operations and introduced mammals on their breeding islands. Mammals are typically brought to remote islands by humans either accidentally as stowaways on ships, or deliberately for hunting, ranching, or biological control of previously introduced species. Introduced mammals have a multitude of negative effects on seabirds including direct and indirect effects. Direct effects include predation and disruption of breeding activities, and indirect effects include habitat transformation due to overgrazing and major shifts in nutrient cycling due to a halting of nutrient subsidies from seabird excrement. There are other invasive species on islands that wreak havoc on native bird populations, but mammals are by far the most commonly introduced species to islands and the most detrimental to breeding seabirds. Despite efforts to remove introduced mammals from these remote islands, invasive mammals are still present on roughly 80% of islands worldwide.
Cats are a popular pet in New Zealand. Cat ownership is occasionally raised as a controversial conservation issue due to the predation of endangered species, such as birds and lizards, by feral cats.
Cat predation on wildlife is the result of the natural instincts and behavior of both feral and owned house cats to hunt small prey, including wildlife. Some people view this as a desirable trait, such as in the case of barn cats and other cats kept for the intended purpose of pest control in rural settings; but scientific evidence does not support the popular use of cats to control urban rat populations, and ecologists oppose their use for this purpose because of the disproportionate harm they do to native wildlife. As an invasive species and predator, they do considerable ecological damage.
Heirisson Prong is a community managed reserve established for the conservation of threatened mammals at Shark Bay in Western Australia. The reserve is at the point of a long narrow peninsula of the same name that juts into Shark Bay from the south.
In biology, overabundant species refers to an excessive number of individuals and occurs when the normal population density has been exceeded. Increase in animal populations is influenced by a variety of factors, some of which include habitat destruction or augmentation by human activity, the introduction of invasive species and the reintroduction of threatened species to protected reserves.
Barry Green also known by his nickname "Cat Man", is an Australian feral cat trapper on Kangaroo Island and self-described conservationist of native Australian wildlife, which is threatened by feral cats both directly through predation and indirectly through transmission of diseases including sarcocystis and toxoplasmosis, which also affect livestock.