Black-footed Ferret - Mustela nigripes

Black-footed Ferret - Mustela nigripes (Audubon and Bachman, 1851).

IUCN STATUS CATEGORY Extinct in the Wild

HABITAT The North American prairie belt. Exclusively lived in and around prairie dog 'towns'.

GEOGRAPHICAL SPREAD Presently restricted to reintroduction sites in Arizona, Montana, South Dakota and Wyoming.

CURRENT POPULATION The Black-footed Ferret became extinct in the wild with the loss of the last known wild population in 1981. Since 1991 over 200 ferrets have been released back into the wild (WWF-Canada, 1997).

SIZE Head and body length between 38 and 50cm. Tail length 11 to 15cm. Males are about 10 per cent larger than females.

WEIGHT Between 0.75 and 1.08kg.

AVERAGE LIFE EXPECTANCY Captives are estimated to live up to 12 years.

NORMAL DIET The Black-footed Ferret preys primarily upon Prairie Dogs although mice, voles, ground squirrels and other small animals are also taken.

NORMAL LIFESTYLE The Black-footed Ferret is nocturnal and lives in the burrows dug by Prairie Dogs. A large area of prairie habitat with a large Prairie Dog population is required to support a very small numbers of ferrets (40 to 60ha for each ferret) (Lowe et al., 1990).

PREVIOUS GEOGRAPHICAL SPREAD Ferrets formerly inhabited the Great Plains from Alberta, Canada, south through the intermontane regions of the Rocky Mountains to the south-western USA. In the 1800s, the Ferret was widely distributed at low densities in ten states: Montana, Wyoming, North and South Dakota, Nebraska, Kansas, Colorado, New Mexico, Oklahoma, and northern Texas (Crane, 1990). It was also found in the extreme eastern portions of Utah and Arizona. In Canada, the species has not been recorded since 1937; by the 1950s it was believed to be extinct in the USA, until the discovery of a small population in South Dakota in the 1960s.

REASONS FOR DECLINE Loss of prey resulting from an extensive campaign to eradicate Prairie Dogs, mainly through poisoning (Crane, 1990). The Black-footed Ferret has declined in direct proportion to the Prairie Dog. Canine distemper is fatal for Black-footed Ferrets and it has decimated many populations. Conversion of land to agricultural use has led to fragmentation of Black-footed Ferret habitat (Crane, 1990). As ferrets live at low densities, a breeding population is spread over a large area. As overall habitat becomes more fragmented, the population becomes less able to reproduce.

CURRENT THREATS Reintroduced populations may become infected with canine distemper, although careful monitoring of other mammals at risk, such as coyotes, has been carried out in the vicinity of the reintroduction areas.

CONSERVATION PROJECTS Captive breeding under the direction of the Wyoming Game and Fish Department in cooperation with the United States Fish and Wildlife Service, has now produced large numbers of ferrets. Research has been undertaken into how to successfully achieve reintroduction without problems occurring from the effects of captivity upon the ferret population (Godbey & Biggins, 1994). In 1991 the initial reintroduction took place when animals were released back into the wild at Shirley Basin, south-eastern Wyoming (US-FWS, 1997). Further populationsare being established in Montana, South Dakota and Arizona (WWF-Canada, 1997). The United States Fish and Wildlife Service aims to establish 10 free-ranging populations of Black-footed Ferrets, comprising a total of 1,500 animals in the wild by the year 2010 (US-FWS, 1997).

SPECIAL FEATURES The last known wild population grew steadily from 60 in 1982 to 129 in 1984 as a result of protection. This trend came to an end in the summer of 1985 when canine distemper infected the ferrets and reduced the population to approximately 31. The remaining animals were captured for a captive breeding programme leaving no known wild population; six died in captivity and the global population of the species in 1985 totalled 25 (Crane, 1990).

REFERENCES

WWF-Canada, 1997. Black-footed Ferret Factsheet. WWW site. cited June 2nd, 1997. Available from Internet: URL: http://www.wwfcanada.org/facts/ferret.html

Crane, C. 1990. The Ferrets that Wouldn't Die. Animals. May/June 1990: 18-23.

Godbey, J. & Biggins, D. 1994. Recovery of the Black-footed Ferret: Looking Back, Looking Forward. Endangered Species Technical Bulletin XIX(1): 10-13.

Lowe, D.W., Matthews, J.R. and Moseley, C.J. (Eds.). 1990. The Official World Wildlife Fund Guide to Endangered Species of North America. Volume 1. Plants and Mammals. Beacham Publishing Inc.: Washington D.C.

Nowak, R.M. 1991. Walker's Mammals of the World. 5th ed. Vol.2. John Hopkins University Press, London. pp. 1113-1114.

Schreiber, A., Wirth, R., Riffel, M. and Van Rompaey, H. 1989. Weasels, Civets, Mongooses and their Relatives, An Action Plan for the Conservation of Mustelids and Viverrids. IUCN/SSC Mustelid and Viverrid Specialist Group. IUCN: Gland, Switzerland. 100 pp.

United States Fish and Wildlife Service, 1997. Black-footed Ferret (Mustela nigripes) Biologue. WWW site. cited June 2nd, 1997. Available from Internet: URL:

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