American Mink

American Mink
Conservation status
Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Family:	Mustelidae
Genus:	Neovison
Species:	N. vison
Binomial name
Neovison vison[2] (Schreber, 1777)

The American Mink, Neovison vison, is a North American member of the Mustelidae family found in Canada and most of the United States, particularly in Alaska. It is related to weasels, otters, European Mink, wolverines, and fishers. It was once grouped with skunks although new genetic evidence has placed skunks in a separate family Mephitidae. A domestic form of American Mink is raised in fur farms for its lustrous fur, which is highly esteemed. Breeders have developed a range of colors from deep black to white. A related marine species, Neovison macrodon, was hunted to extinction in the 19th century.

Physical description

American mink from a fur farm in Cox’s Cove, Newfoundland, Canada.

The Mink's long slim body is covered in glossy, thick dark brown fur with a white patch under the chin. They have short legs with partially webbed feet, which make them excellent swimmers. They can be found in wooded areas and fields near streams and lakes. They do not dig burrows, but instead take over dens abandoned by other animals.

Mink are semi aquatic predators able to hunt both aquatic and terrestrial prey. They can dive under water like an otter to capture fish, crayfish, and frogs. They can also capture terrestrial prey like birds, snakes, mice, voles, and rabbits. Mink are generalist predators focusing on whatever prey is most available and easily captured. These animals are mainly active at night and do not hibernate. Their predators include coyotes, Great Horned Owl, and wolves. They are also trapped for their fur. Their numbers have been reduced due to loss of habitat, the effects of pollution on their aquatic food supply, and the mixing of domestic mink genes into the wild mink gene pool.^[3]

They are usually solitary animals. Mating occurs from early February through early April; males and females may have more than one partner. Females give birth to 4–5 kits per litter once a year. While mortality is extremely high in the early months of the life of the American Mink, animals that do survive the first year can live as long as three years in the wild.^{[citation needed]} In captivity, mink can live 10–12 years.^{[citation needed]} The mink is found in places which suit its habits throughout almost all North America, from Florida to the Arctic. An endangered subspecies, the Everglades Mink (Mustela vison evergladensis), is endemic to the Florida Everglades.

Fur farms

Mink farm in Wisconsin.

There is debate about the subject of fur farming. Many people argue that fur farming is cruel and should be eliminated completely. But many agree that fur farming is necessary, because it protects wild fur bearers from over harvest. Before fur farming was developed many animals, like the Sea Mink, were driven to extinction due to over harvesting them for their fur. Many other animals like the fur seal, sea otter, river otter, and beaver had their populations drastically reduced from over harvesting. If fur farming were eliminated, the price of fur might increase. Wild fur bearing animals might again be in danger of over harvest.

A 2006 study in Denmark concluded that, due to frequent escapes from existing mink farms, “Closing mink farms may result in a crash of the free-ranging population, or alternatively it may result in the establishment of a better-adapted, truly feral population that may ultimately outnumber the population that was present before farm closures.” The study reported that more information would be necessary to determine the outcome.^[4] Another Danish study reported that a significant majority of the “wild” mink were mink which had escaped from fur farms. 47% had escaped within two months, 31% had escaped prior to 2 months, and 21% “may or may not have been born in nature.”^[5]

Animal rights activists have also released several thousand domestic mink causing negative environmental consequences. Domestic mink, which are bred in fur farms, are different from wild mink. Domestic mink are found to have 19.6% smaller brains, 8.1% smaller hearts, and 28.2% smaller spleens than wild mink.^[6][7] Because of these physical differences, domestic mink may not be suited for life in the wild. A University of Copenhagen study found that most domestic mink that escape from fur farms die in less than two months.^[5]

This data is contested by M. Hammershøj and M.C. Forchhammer, who studied the survival rate of escaped mink in Denmark, then compared that data to similar studies in the US and Sweden. The authors concluded that the survival rate for recently released mink is lower than for wild mink, but if mink survive at least two months, their survival rate is the same as for wild mink. The authors suggest that this is due to the rapid behavioural adaptation of the animals.^[5] A biologist with the Washington State Department of Fish and Wildlife commenting on a mink farm release concurs, stating that "These things will survive and reproduce as long as they have something to survive on."^[8]

Domestic mink are larger than wild mink which may cause problems with the ecosystem when they escape. Mink are solitary, territorial animals and are intolerant of other mink. In times of overpopulation, mink control their own numbers by either killing each other through direct conflict or by causing weaker mink to be driven from territory until starvation sets in.^[9] When hundreds or thousands of released domestic mink flood an ecosystem, it causes a great disturbance for the wild mink, resulting in the deaths of the majority of the released mink and many of the wild mink from starvation or injuries incurred fighting over territory.^[9] When a domestic mink survives long enough to reproduce, it may cause problems for the wild mink populations.^[3] The adding of weaker domestic mink genes into wild mink populations is believed by some to have contributed to the decline of mink populations in Canada.^[3]

Feral populations

An American mink in Lithuania.

Some American Mink have established themselves in the wild in Newfoundland, Europe and South America due to escapes or intentional release by animal rights activists from fur farms. In parts of Europe, tens of thousand were intentionally introduced by the Soviet Union over a period of several decades, to provide a new game animal for trappers, with disastrous population declines of the European Mink as result.^{[citation needed]} It is also thought that the introduction of feral mink to Mongolia may be having negative impacts on native fish and wild birds of the region, however, as of 2006, no studies had yet been done to assess its impact ^[10].

The larger American male will mate with European Mink females earlier in the spring than the males of the same species; no offspring are born, but the females do not then breed again that season.^{[citation needed]} This is believed by some^[who?] to have contributed to the decline of the European Mink. American Mink have also been implicated in the decline of the Water Vole in the United Kingdom and linked to the decline of water fowl across their range in Europe. They are now considered vermin in much of Europe and are hunted for the purpose of wildlife management.^[11]

Mink intelligence

Like their cousins, the otters, mink are very playful. They are very inquisitive, highly intelligent animals. A study was performed that compared the learning ability of mink to ferrets, skunks, and house cats.^[12] The animals were tested on their ability to remember different shapes. The order of ability of remembering these different shapes were from best to worst; mink, ferrets, skunks and cats. Mink were in fact found to be more intelligent than certain groups of primates. After considerable training, mink were also found to learn after only one trial. This is a phenomenon usually only observed in higher primates.

Mink as pets

Mink as pet

Despite the fact that they are inquisitive, playful and cute, mink can be tamed but do not make good pets because they have strong jaws, very sharp teeth, can be highly aggressive, and are very active. Most people do not have the knowledge, or the patience to properly care for a wild mink as a pet.

Even though domestic mink have been bred in captivity for around a hundred years, they have not been bred to be tame. Domestic mink have been bred for size, fur quality, and color. However, the US Fur Commission claims that "mink are truly domesticated animals" based on the number of years they have been kept on fur farms.^[13]

Transmissible mink encephalopathy

Transmissible mink encephalopathy (TME) is a prion disease of mink, similar to BSE in cattle and scrapie in sheep. A 1985 outbreak of TME in Stetsonville, Wisconsin resulted in a 60% mortality rate for the mink.^[14] Further testing revealed that this agent is transmissible between mink, cattle and sheep. The Stetsonville outbreak may have been due to the animals being fed the carcasses of other infected animals.^[15]

See also

• Aleutian disease
• Information related to Neovison vison from Wikispecies.

• Media related to Neovison vison at Wikimedia Commons

References

1. ^ Reid, F. & Helgen, K. (2008). Neovison vison. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 21 March 2009. Database entry includes a brief justification of why this species is of least concern
2. ^ Grubb, Peter (16 November 2005). Wilson, D. E., and Reeder, D. M. (eds). ed. Mammal Species of the World (3rd edition ed.). Johns Hopkins University Press. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3/browse.asp?id=14001484. 
3. ^ ^{a b c} Bowman, J., A. Kidd, R. Gorman, A. Schulte-Hostedde (2007) Assessing the potential for impacts by feral mink on wild mink in Canada. Biological Conservation 139: 12-18.
4. ^ Hammershøj, Mette, Justin M.J. Travis and Catriona M. Stephenson (2006) Incorporating evolutionary processes into a spatially-explicit model: exploring the consequences of mink-farm closures in Denmark. Ecography 29(4): 465-476
5. ^ ^{a b c} Hammershøj, M. (2004) Population ecology of free-ranging American mink Mustela vison in Denmark. PhD thesis, National Environmental Research Institute, Kalø, Denmark. 30 pp.
6. ^ Kruska, D. (1996) The effect of domestication on brain size and composition on the mink. J. Zoo., Lond. 239: 655.
7. ^ Kruska, D. and A. Schreiber (1999) Compatative morphpmetrical and biochemical-geneic investigations in wild and ranch mink. Acta Theriologica 44(4): 382.
8. ^ Schwarzen, Christopher (2003) Freed mink attack Sultan farms. The Seattle Times, August 29
9. ^ ^{a b} Dunstone, N. (1993) The Mink. London.
10. ^ Clark EL, Munkhbat J, Dulamtseren S, Baillie EM, Batsaikhan N, Samiya R, Stubbe M. 2006. Mongolian Red List of Mammals, Regional Red List Series 1, Zoological Society of London, London.
11. ^ Haworth, Jenny (3 February 2009) "National cull may exterminate UK mink". Edinburgh. The Scotsman.
12. ^ Doty, Barbara A., C. Neal Jones and Larry A. Doty (1967) Learning-Set Formation by Mink, Ferrets, Skunks, and Cats. Science 155(3769): 1579–1580.
13. ^ Fur Commission USA (2008) Mink Farming in the United States (revised edn). Colorado.
14. ^ Tenembaum, David (2007) Unfolding the Prion Mystery. Grow online
15. ^ Scientific papers on Spongiform Disease by R.F. Marsh

• Hellsetde, P., E. Kallio and I. Hanski (2000) Survival rate of captive-born released least weasels in Southern Finland. Mammal Review 30:3/4