Taxonomic name: Felis catus Linnaeus, 1758
Common names: cat, domestic cat (English), feral cat (English), Hauskatze (German), house cat (English), poti (Maori), pusiniveikau (Fiji)
Organism type: mammal
Felis catus was domesticated in the eastern Mediterranean c. 3000 years ago. Considering the extent to which cats are valued as pets, it is not surprising that they have since been translocated by humans to almost all parts of the world. Notable predators, cats threaten native birdlife and other fauna, especially on islands where native species have evolved in relative isolation from predators.
Felis catus is a small animal in the wild (up to 5kg, but more commonly 1.5 -3.0kg) but may be considerably heavier when domesticated. Colour is extremely variable in domesticated varieties and feral cats commonly revert to black, tabby or tortoiseshell with varying extents of white starting from the belly and breast.
agricultural areas, coastland, natural forests, planted forests, range/grasslands, riparian zones, ruderal/disturbed, scrub/shrublands, tundra, urban areas, wetlands
Feral cats adapt to a variety of habitat types and circumstances. On the Australian continent they inhabit forests and woodland habitats in eastern, western and northern parts of the country (Dickman 1996). On Hahajima Island, Japan, feral cats have been observed widely in various kinds of habitats, including primary forests (Kawakami and Higuchi 2002). On Macquarie Island, (a sub-Antarctic Australian island) most cats live in herb-field or tussock grassland (Brothers Skira and Copson 1985), showing an ability to adapt to difficult terrain. A study of the habitat use and diet of feral cats in a Mediterranean habitat in a riparian reserve in central California (Hall et al. 2000, in Brickner 2003) can probably reflect on the situation in other areas with similar climatic areas. Cats in the reserve seemed to strongly prefer staying in riparian habitat. Hall and collegues (2000) suggest that this habitat provides ample cover and perhaps a variety of prey, especially birds. Cats in the study foraged mostly in the adjacent fields and annual grasslands and, to a lesser extent, in the riparian habitat (in Brickner 2003).
The most obvious impact of feral cats is the predatory impact they exert on native prey populations; this has resulted in the probable local or regional decline or extinction of many species (Dickman 1996). However, unambiguous evidence of cats causing a decline in a prey species is difficult to find as other factors, such as other predator species, may also be involved in the decline (Dickman 1996). One exception to this is a study by Saunders (1991) which showed that cats killed 7% of nestlings of red-tailed cockatoos (Calyptorhynchus magnificus) over 11 breeding seasons in Western Australia. Several reintroduction programmes in Australia have failed, due to the predation pressure exerted by feral cats, often in conjunction with foxes. For example, the success of the reintroductions of the golden bandicoot (Isoodon auratus) and the burrowing bettong (Bettongia lesueur) in the Gibson Desert, Western Australia was hindered primarily by feral cat predation. In general, the predatory impact of cats primarily affects birds and small to medium-sized mammals (Dickman 1996). Endangered species around the world are threatened by the presence of cats, including the black stilt (see Himantopus novaezelandiae in the IUCN Red List of Threatened Species) (New Zealand), the Okinawa woodpecker (see Sapheopipo noguchii in IUCN Red List of Threatened Species) (Japan) and the Cayman Island ground iguana (see Cyclura lewisi in IUCN Red List of Threatened Species), to list just some of the many species effected.
Changes in island fauna after the introduction of cats can provide compelling evidence of their predatory impact. Cats have been introduced to 40 islands off the coast of Australia; seven off the coast of New Zealand and several dozen islands elsewhere in the Pacific (Dickman 1992a, Veitch 1985, King 1973 1984, in Dickman 1996). Feral cats have been implicated in the decline of at least six species of island endemic birds in New Zealand, including the Stephens Island wren, the sooty shearwater (Puffinus griseus) and the kakapo (Strigops habroptilus), as well as 70 local populations of insular birds (King 1984, in Dickman 1996). The elimination of cats often leads to an increase in the population size of prey species. For example, following removal of cats from Little Barrier Island, New Zealand, the stitchbird (Notiomystis cincta) increased from less than 500 individuals to 3000 individuals in just a few years (Griffin et al. 1988, in Dickman 1996).
Feral cats are not to be confused with the three species of wild cats found throughout continental Europe, southwestern Asia, and the savannah regions of Africa. These are the African wild cats (Felis silvestris lybica), European wild cats (F. silvestris silvestris) and Asiatic wild cats (F. silvestris ornata). African wild cats are found in appropriate habitat throughout Africa and the Arabian Peninsula. European wild cats are found throughout Europe and western Russia and Scandinavian countries. Asiatic wildcats are found in the Middle East, southern Russia, western China and western India. Domestic cats (F. catus) are thought to be descended from African wild cats and are found virtually worldwide in association with humans (IUCN Cat Specialist Group 1996a, IUCN Cat Specialist Group 1996b, IUCN Cat Specialist Group 1996c, in University of Michigan 2006).
Introduction pathways to new locations
Ship: Many ships of the 18th and 19th centuries were infested with rats and so carried cats to control them.
Transportation of domesticated animals: Taken by humans as pets then left behind or the young dispersed.
Local dispersal methods
Natural dispersal (local):
Cats were first domesticated in Egypt around 2000BC (Serpell 1988, in Coleman et al. 1997, in Brickner 2003) and brought to Britain by 300AD by the Romans. European colonists introduced them around the globe (Coleman et al. 1997, in Brickner 2003). As cats are often revered as pets in our society this raises the moral dilemma of how to handle them when they have become a threat to native wildlife. Brickner (2003) suggests that animal rights organisations that condemn cat control via killing are over-looking the approximately 275 million animals killed by 9 million cats in Britain alone (Woods et al. in press). Obviously there are two quite different situations for management of the species, depending on the status of the cat: one is where a cat is a domesticated household pet and the other is when a cat has gone wild or feral and has no owner to protect and feed it.
When a cat is a pet, there are a number of ways in which to help prevent damage caused to wildlife. Brickner (2003) suggests keeping a cat in at night, fitting it with a bell, neutering the animal when it is young and giving it toys. However, the divided results of several investigations shows that the positive outcome of such actions is uncertain. Barrette (1998) found that fitting cats with bells has no significant effect on the amount of prey caught, whereas Ruxton et al. (2002) found that equipping cats with bells reduced prey delivery rates by about 50% (in Brickner 2003). Woods, McDonald and Harris (2003) found that the number of birds and herpetofauna brought home by cats was significantly lower in households that feed birds (but the number of actual different types of bird species killed was greater in households that feed birds). The number of mammals brought home per cat was lower when cats were equipped with bells or kept indoors at night, however, the number of herpetofauna brought home was greater when cats were kept in at night. The outcome of this is that there appears to be a subjective choice to be made as to whether it is more important to protect herpetofauna or mammals. Obviously, if the mammals being caught are introduced species, such as rats and mice, this raises another dilemma.
In the second situation, when a cat is feral and threatening wildlife, a more severe means of controlling cats appears justified. In 1992 the Australian Parliament passed the Endangered Species Protection Act 1992, which obligates the commonwealth to provide a Threat Abatement Plan (TAP) for each listed threatening process, including one for feral cats (Brickner 2003). The key objectives of the feral cat TAP are: eradicate feral cats from islands where they threaten vulnerable native animals; prevent feral cats from occupying new islands where they may be a threat to native communities; promote the recovery of species threatened by feral cats; improve the effectiveness and humaneness of cat control methods and improve the understanding of the impacts of feral cats on native animals. The use of visual lures (such as feathers and cotton wool) and attractants (such as tuna oil) are currently being tested in an effort to attract greater numbers of feral cats to traps and baits. The impact of feral cats on native wildlife is being studied in various parts of Australia in order to have it quantified (Brickner 2003).
Notes on trapping from Aliens-L (Jill Key (Pacific Invasives Learning Network) pers.comm., 20 September 2008; Reese Brand Phillips pers.comm., 19 September 2008).
Male and female feral cat home ranges overlap (Say and Pontier 2004). The mean home range for feral cats in Hawaiian forests was 5.74km2 for males and 2.23km2 for females (Smucker et al. 2000). Australian studies have given mean home ranges of 7 to 28 hectares for domestic cats and up to 249.7 hectares for feral cats; while a New Zealand study posted home ranges of between 75 hectares and 985 hectares. Prey availability is a primary factor in determining home range size for feral cats (Edwards et al. 2001; Barratt 1997). Cat activity is bimodal, with peaks near dawn and dusk (Konecny 1987).
The diet of feral cats on islands may vary significantly to that of feral cats on the mainland, with cats often taking advantage of alternative food sources. On the tiny 28 hectare Herekopare Island, New Zealand, for example, there are no introduced or native species of mammals. Prior to elimination of feral cats there in 1970, fairy prion (see Pachyptila turtur in IUCN Red List of Threatened Species) comprised the bulk of the diet with other sea birds and occasional land birds making up most of the remainder (Fitzgerald and Veitch 1985, in Dickman 1996). The weta (a native insect in the order Orthoptera) also appeared to be important to individual cats; two cats' stomachs were found to contain over 100 insects each. Similarly, in the Galapagos Islands, birds are an important component of the feral cat's diet, with cats sometimes taking birds of similar mass to themselves, such as frigate birds (Fregata spp.), pelicans (Pelecanus spp.) and flightless cormorants (Phalacrocorax spp.) (Konecny 1987, in Dickman 1996). On Aldabra Atoll, Seychelles, hatchlings of the green turtle (see Chelonia mydas in IUCN Red List of Threatened Species) are seasonally predominant in the diet of feral cats (Seabrook, 1989). On Christmas Island, the introduced black rat (Rattus rattus) comprises almost one third of the diet of feral cats by weight, however, 21% of the diet is comprised of the large flying-fox (see Pteropus melanotus in IUCN Red List of Threatened Species) and 28% of the imperial pigeon (see Ducula whartoni in IUCN Red List of Threatened Species) (Tidemann et al. 1994, in Dickman 1996).
Click here to see Major prey of feral cats in Australia (source: Dickman 1996).
Domestic cats are intensive breeders, maybe due to the seasonal estrous cycle of the females, during which each female comes into heat several times until pregnancy or end of cycle (Gunther and Terkel 2002, in Brickner 2003). A female cat reaches reproductive maturity between 7 to 12 months of age can be in estrous as many as five times a year (Ogan and Jurek 1997, in Brickner 2003). The gestation period lasts 63 to 65 days (Nowak 1991, in Brickner 2003) and the average litter is four to six kittens (O’Donnell 2001, in Brickner 2003). Cats can reproduce any month of the year, where food and habitat is sufficient. An adult female may produce three litters per year (Fitzwater 1994, in Brickner 2003).
Gestation: 65 days. Weaning: 35-40 days. Sexual maturity: 9 months.
This species has been nominated as among 100 of the "World's Worst" invaders
Reviewed by: Major update under progress
Dick Veitch, Auckland, New Zealand.
Compiled by: Dick Veitch, Auckland, New Zealand & IUCN/SSC Invasive Species Specialist Group (ISSG)
Last Modified: Monday, 21 September 2009