California Department of Fish and Wildlife

Introductions of Small Carnivores Around the World

Small carnivores have been widely introduced around the world. Some escaped from captivity and others were purposely released in order to establish fur-bearing animal populations or to control rodents or other pest animals. Here are some examples of introductions of small carnivores, those weighing about 7 kg (15 pounds) or less.

  • For more information about the species listed below, go to the Mammal Species of the World search page, by common or scientific name.

The American mink, the small Indian mongoose, and the domestic cat have been particularly damaging to wildlife in various parts of the world:

American mink, Mustela vison

United Kingdom

Feral mink, resulting from escaped and illegally released fur farm animals, are widespread and abundant in Britain. Concerns that these non-native predators were a threat to wildlife and agricultural interests lead to The Mink Keeping Order 1997, which "prohibits absolutely the keeping of mink on certain off-shore islands of Great Britain and in certain parts of the Highland Region of Scotland and prohibits the keeping of mink in the rest of Great Britain except under licence... "

"The mink is the first introduced carnivore in Britain since the domestic cat, and its predatory nature and potential impact on native prey species has been the subject of much debate amongst scientists and naturalists. Declines in water fowl numbers, fish stocks and small native mammals such as the water vole Arvicola terrestris have all been attributed to the arrival of mink in Britain. Mink are opportunistic, generalist predators with a wide prey base but some species may be more vulnerable than others. Mink might have a greater impact on water vole populations than on other species due to the linearizing forces of riparian habitat management and agricultural intensification that confine the species to a narrow ribbon of riverbank vegetation." - Wildlife Conservation Research Unit, University of Oxford. The "Water Vole (Arvicola terrestris) faces extinction in the Britain, probably due to the impact of American Mink," - Oxford's University's Wildlife Conservation Research Unit

Ecological risks of escaped American mink in Britain. - The Mammal Society, U.K.

In recent years, animal rights activists have broken into fur ranches and illegally released thousands of American mink in the U.K., adding to the concerns of the public in general and conservationists in particular. However, local Animal Rights advocates have questioned the extent of impact of the non-native American mink on British wildlife, claiming, "The mink is related to the otter, stoat, weasel, pine marten and polecat, and native British wildlife are fully familiar with the hunting methods of these mustelids, and as such the mink should not pose an unnatural threat to wildlife. Where there is any detrimental effect on wildlife by mink "the important fact is that the effect is local: nowhere in the UK have mink caused widespread population declines." - Dr N. Dunstone

[More information on the threat to the water vole is available from Water Vole Watch, Cheshire Wildlife Trust, and from Water Vole Fact Sheet, The Mammal Society, U.K.]


"The import of mink for breeding unfortunately led to some animals escaping and establishing themselves in the wild. This newcomer is not welcome because it is a vicious predator and causes considerable damage. There have been attempts to hold the number of wild mink in check, but the creature has proven to be incredibly adaptable and has spread throughout the country."

- Icelandic Agricultural Information Service , 1997


"... Black Guillemot populations are known to be dwindling in the Gulf of Finland, partly due to Mink (Mustela vison) predation,... " - Conservation of Arctic Flora and Fauna

"The mink probably has affected native species more than the raccoon dog (Kauhala 1996a). This is because it has also colonized the outer archipelagos of the Baltic Sea, where such a predator has not existed earlier." - Alien Species in Finland, P. Nummi

"Seabirds appear to differ in their ability to adapt to mink predation... The black guillemot Cepphus grylle and the razorbill Alca torda, which feed their young in crevice nests for several weeks, are more vulnerable than eiders. "- Alien Species in Finland, P. Nummi

American mink have also been introduced in Spain, on the Japanese island of Hokkaido, and in Sakhalin and the Kuril Islands.

The threat to European mink by introduced American mink

"Currently in Europe, the European mink is a critically endangered species of mustelids and still common mainly in the two areas: in small sized area at the western border between Spain and France and substantially larger area (about 180000 square km) located in north-eastern Belarus and the adjacent regions of Russia." "The decline of the native mink populations is based on both aggressive encounters from the naturalized American mink towards to the European mink and the increase of the American mink's reproductive rate in its expanding populations. Resource competition is less significant in the process." - Study on population biology of the European mink, National Academy of Sciences of Belarus, 1998

"The European mink (Mustela lutreola) is threatened and declining almost throughout its range. A chief cause is its interaction with the introduced and more numerous American mink (Mustela vison). Where they are sympatric, the larger American mink males mate with European mink females, which then do not permit other males to approach them. But the embyros (sic) resorb at an early stage, and the female leaves no offspring for that year, while the American mink females are productively mated by conspecific males." - Extinction by Hybridization and Introgression, by Judith M. Rhymer and Daniel Simberloff , Extinction by hybridization and introgression, Annu. Rev. Ecol. Syst. 1996, Vol. 27: 83-109

Conservation Plan for the European mink

Small Indian mongoose, Herpestes auropunctatus

"Introduced to Cuba, Dominican Republic, Fiji Isls, Hawaiian Isls, Jamacia (sic), Japan, Puerto Rico, Surinam, West Indies, and many other tropical regions." - Mammal Species of the World. This small mongoose, weighing only about a pound and a half (700 gm), has had devastating effects on wildlife. Importation of Herpestes auropunctatus into the United States and its territories is prohibited by federal law, the Lacey Act.

  • Small mammal predators invade Hawai'i - USGS, 1999

  • Information about the Indian mongoose in Hawaii - Hawaiian Ecosystems at Risk project

  • Impact of the mongoose of birds on Molokai

  • Virgin Islands
    St. Croix Ground Lizard (Ameiva polops) - "There is circumstantial evidence that correlates the decline of A. polops with the introduction of the small Indian mongoose (Herpestes auropunctatus) to the Virgin Islands in 1984."
    Virgin Islands Tree Boa (Epicrates monensis granti) - "High densities of the introduced Indian mongoose (Herpestes auropunctatus) on St. Thomas, St. John, Tortola, and Jost Van Dyke probably contributed to population decline of the tree boa."

  • Mongooses threaten the survival of white-breasted thrasher (Ramphocinclus brachyurus) on the islands of St. Lucia and Martinique.

  • Mongooses contribute to the extinction or near-extinction of the Jamaican petrel (Pterodroma caribbaea) in Jamaica.

  • Mongooses contribute to the decline of the West Indian whistling-duck (Dendrocygna arborea) in Jamaica.

  • Mongooses threaten the Jamaican iguana (Cyclura collei) and other West Indian rock iguanas.

Domestic cats, Felis catus - Link to Cats and Wildlife Page

Examples of other species of small carnivores introduced around the world:

Domestic ferrets, Mustela putorius furo - Link to World Distribution of Wild Domestic Ferrets

Stoat, Mustela erminea. Hundreds of stoats were introduced into New Zealand starting in 1883 (Laycock, 1966, p. 135).

  • "The introduction of stoats is commonly regarded as one of the worst mistakes ever made by European colonists in New Zealand. Stoats are now by far the most common of the mustelids and are widespread in forest and on farmland. They are extremely agile climbers and have a devastating effect on native birds by preying on adult and young birds and raiding nests for eggs." - New Zealand Department of Conservation

  • As examples, stoats threaten the Mohua, (yellowhead) and kiwi in New Zealand.

Least weasel, Mustela nivalis. Introduced into New Zealand - New Zealand Department of Conservation

European mink, Lutreola lutreola. Introduced on the Kuril Islands

Stone marten, Martes foina. A breeding population of this ferret-sized mustelid is established in Wisconsin.

  • "Stone martens are a species native to Europe and Asia. They were released in southern Wisconsin in the early 1970s, where they've established a breeding population. Stone martens are 23-31 inches long (including the tail), weigh 1-4.5 pounds and are pale gray to brown with a white throat patch." - Wisconsin Department of Natural Resources
  • Also, see Long, C.A. 1995. Stone marten (Martes foina) in southeast Wisconsin, U.S.A. Small Carnivore Conservation, 13:14
  • Mammal Species of the World

Japanese marten, Martes melampus. Introduced on Sado Island

Indian gray mongoose, Herpestes edwardsi.

American raccoon, Procyon lotor. "During the 1930s the raccoon was successfully introduced into Germany and the Soviet Union. Today, its range has expanded to include Luxembourg, West Germany, the Netherlands, and France." - Environment Canada.

Raccoon dog, Nyctereutes procyonoides. Introduced into Europe and the former USSR (including Belarus) [photo]

Arctic fox, Alopex lagopus. Extensively introduced in the Aleutian Islands. - IUCN/SSC Canid Specialist Group

Red fox, Vulpes vulpes. Widely introduced, mainly for fur and for sport hunting.

  • "European subspecies introduced into Eastern states (e.g. Virginia) of North America in the 17th Century, and mixed with local subspecies then moving southwards as habitat changed (forest clearance); also introduced to Australia." - IUCN/SSC Canid Specialist Group
  • "The European Red Fox Vulpes vulpes was introduced into Australia during the 1860's and 1870's..." - Victoria Natural Resources and Environment
  • Since the late 1800s, non-native subspecies of North American red foxes have been imported and released or escaped into California. They were established as a breeding population in California for 110 years before they become a serious threat to California wildlife in recent decades.

Grey zorro, Dusicyon griseus. A small South American fox, was introduced to Tierra del Fuego in 1951 to control European rabbits. - IUCN/SSC Canid Specialist Group