Cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...

s are an

invasive species in Australia Invasive species in Australia are a serious threat to the native biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic ('' genetic variabi ...

. Because they are not native to

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

and were only introduced by colonisers as pets in the early 1800s, native Australian animals did not

co-evolve In biology, coevolution occurs when two or more species reciprocally affect each other's evolution through the process of natural selection. The term sometimes is used for two traits in the same species affecting each other's evolution, as well ...

with them. , some 3.8 million

domestic cats The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...

and up to 6.3 million

feral cats A feral cat or a stray cat is an unowned domestic cat (''Felis catus'') 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 ...

continue to live in Australia. Every year domestic and feral cats in Australia kill 1,067,000,000 mammals, 399,000,000 birds, 609,000,000 reptiles, and 92,000,000 frogs. As one of the most ecologically damaging and the most costly invasive species in Australia,

predation Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

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 Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the Endling, last individual of the species, although the Functional ext ...

of at least 22

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

Australian mammals since the arrival of Europeans. For

biosecurity Biosecurity refers to measures aimed at preventing the introduction and/or spread of harmful organisms (e.g. viruses, bacteria, etc.) to animals and plants in order to minimize the risk of transmission of infectious disease. In agriculture, ...

reasons, any cats that are imported into Australia must meet conditions set by the Department of Agriculture, Fisheries and Forestry.

Historical context

Historical records date the introduction of cats by European colonisers to Australia at around 1804 and that cats first became

feral 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 ...

around Sydney by 1820. In the early 1900s concern was expressed at the pervasiveness of the cat problem.

Domesticated cats

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. Responsible cat owners in Australia keep their cats indoors at all times to prevent them from killing native animals. Almost 30% of Australian households keep at least one domesticated cat. Domesticated cats must be microchipped in every

state of Australia The states and territories are federated administrative divisions in Australia, ruled by regional governments that constitute the second level of governance between the federal government and local governments. States are self-governing po ...

except

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

. All pet cats past six months of age must be desexed in the

Australian Capital Territory The Australian Capital Territory (commonly abbreviated as ACT), known as the Federal Capital Territory (FCT) until 1938, is a landlocked federal territory of Australia containing the national capital Canberra and some surrounding township#Aust ...

, Tasmania,

South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest o ...

and

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to t ...

Feral cats

Ecological damage

Feral cat A feral cat or a stray cat is an unowned domestic cat (''Felis catus'') 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 ...

s are a major

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adv ...

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. A study in the 2010s estimated that each feral cat kills 740 wild animals per year. 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. Environmentalists conclude that feral cats have been an ecological disaster in Australia, inhabiting almost all of its

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

s, and being implicated in the

of several

marsupial Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in ...

and

placental Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguishe ...

mammal species. A field experiment conducted in Heirisson Prong (Western Australia) compared small

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur ...

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. Cats may play a role in Australia's altered ecosystems; with foxes they may be controlling introduced

rabbits Rabbits, also known as bunnies or bunny rabbits, are small mammals in the family Leporidae (which also contains the hares) of the order Lagomorpha (which also contains the pikas). ''Oryctolagus cuniculus'' includes the European rabbit sp ...

, 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 Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

species to be lost since European settlement, the paradise parrot. Cats in Australia have no natural predators except

dingo The dingo (''Canis familiaris'', ''Canis familiaris dingo'', ''Canis dingo'', or ''Canis lupus dingo'') is an ancient ( basal) lineage of dog found in Australia. Its taxonomic classification is debated as indicated by the variety of scienti ...

es and

wedge-tailed eagle The wedge-tailed eagle (''Aquila audax'') is the largest bird of prey in the continent of Australia. It is also found in southern New Guinea to the north and is distributed as far south as the state of Tasmania. Adults of this species have lo ...

s, and as a result, they are

apex predator An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic lev ...

s where neither the dingo nor the eagle exists. Also, dingos do not appear to affect the activity of cats.

Claimed benefits

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

Economic impacts

Cats are the costliest

. The cost of invasive cats to the national economy is estimated to be nearly over the 60 years up to 2021, with most of the cost spent on

population control Population control is the practice of artificially maintaining the size of any population. It simply refers to the act of limiting the size of an animal population so that it remains manageable, as opposed to the act of protecting a species from ...

. This cost way outstrips the next most costly invasive species, with

rabbits in Australia European rabbits (''Oryctolagus cuniculus'') were first introduced to Australia in the 18th century with the First Fleet, and later became widespread likely because of Thomas Austin. Such wild rabbit populations are a serious mammalian pest an ...

coming in at nearly .

Control

Pintupi The Pintupi are an Australian Aboriginal group who are part of the Western Desert cultural group and whose traditional land is in the area west of Lake Macdonald and Lake Mackay in Western Australia. These people moved (or were moved) into ...

, Nyirripi and other Western Desert peoples in

and

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an Australian territory in the central and central northern regions of Australia. The Northern Territory shares its borders with Western Aust ...

have been hunting cats to use as a food source and for

bush medicine Bush medicine comprises traditional medicines used by Indigenous Australians, being Aboriginal and Torres Strait Islander people. Indigenous people have been using various components of native Australian flora and some fauna as medicine for ...

for decades, but in 2015 they were also participating in a program with ecologists to help monitor and reduce cat predation on

threatened species Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of '' critical depen ...

. Varmint hunters of feral cats in Australia face backlash and even

death threat A death threat is a threat, often made anonymously, by one person or a group of people to kill another person or group of people. These threats are often designed to intimidate victims in order to manipulate their behaviour, in which case a d ...

s for the

culling In biology, culling is the process of segregating organisms from a group according to desired or undesired characteristics. In animal breeding, it is the process of removing or segregating animals from a breeding stock based on a specific tr ...

of the

. Since 2016, a program on

Kangaroo Island Kangaroo Island, also known as Karta Pintingga (literally 'Island of the Dead' in the language of the Kaurna people), is Australia's third-largest island, after Tasmania and Melville Island. It lies in the state of South Australia, southwest ...

aims to fully eradicate the island's feral cat population, estimated at between 3000 and 5000, by 2030. 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. 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 The state of the art (sometimes cutting edge or leading edge) refers to the highest level of general development, as of a device, technique, or scientific field achieved at a particular time. However, in some contexts it can also refer to a level ...

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 The Kangaroo Island dunnart (''Sminthopsis aitkeni'') is a dark sooty-grey coloured dunnart species first described in 1969, with paler underparts of its body. It has an average body length of 170–198 mm, a snout to anus length of 80– ...

and

southern brown bandicoot The southern brown bandicoot (''Isoodon obesulus'') is a short-nosed bandicoot, a type of marsupial, found mostly in southern Australia. It is also known as the quenda in South Western Australia (from the Noongar word ''). Taxonomy George Shaw ...

Phantom cats

The numerous sightings of

phantom cat Phantom cats, also known as Alien Big Cats (ABCs), are large felids such as leopards, jaguars and cougars which allegedly appear in regions outside their indigenous range. Sightings, tracks and predation have been reported in a number of countr ...

s in Australia include the

Gippsland phantom cat Phantom cats, also known as Alien Big Cats (ABCs), are large felids such as leopards, jaguars and cougars which allegedly appear in regions outside their indigenous range. Sightings, tracks and predation have been reported in a number of countrie ...

and the Blue Mountains panther. Australian

folklore Folklore is shared by a particular group of people; it encompasses the traditions common to that culture, subculture or group. This includes oral traditions such as tales, legends, proverbs and jokes. They include material culture, rangin ...

holds that some feral cats have grown so large as to cause inexperienced observers to claim sightings of

cougars in Western Australia The premise that there were cougars in Western Australia was widely believed during the 1970s. There are several theories as to how they were introduced. The most popular theory was that United States servicemen brought four cougar kittens to Wes ...

. While this rarely occurs in reality, large specimens are occasionally found: in 2005, a feline was measured to be 176 cm from the tip of its nose to the tip of its tail in the

Gippsland Gippsland is a rural region that makes up the southeastern part of Victoria, Australia, mostly comprising the coastal plains to the rainward (southern) side of the Victorian Alps (the southernmost section of the Great Dividing Range). It cove ...

area of

Victoria Victoria most commonly refers to: * Victoria (Australia), a state of the Commonwealth of Australia * Victoria, British Columbia, provincial capital of British Columbia, Canada * Victoria (mythology), Roman goddess of Victory * Victoria, Seychelle ...

. Subsequent

DNA test Genetic testing, also known as DNA testing, is used to identify changes in DNA sequence or chromosome structure. Genetic testing can also include measuring the results of genetic changes, such as RNA analysis as an output of gene expression, or ...

s showed it to be a feral cat.

References

External links

Feral Cat ''Felix catus''
Department of Sustainability, Environment, Water, Population and Communities

- Department of Sustainability, Environment, Water, Population and Communities
Management of cats in Australia
- Australian Veterinary Association
Australian Companion Animal Council
*{{YouTube, id=b93IBwJ_Yow, title=Shooting Cats: Australia's War On Feral Cats Fauna naturalised in Australia Invasive animal species in Australia