Black-footed Ferret
(Mustela nigripes)Status: Extirpated
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Black-footed Ferret(Mustela nigripes)Status: Extirpated |
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Black-footed Ferret (Mustela nigripes) Status: Extirpated Description: The Black-footed Ferret is a mammal belonging to the Mustelidae family. Mustelids have scent glands under their tail, long slender bodies, short legs and sharp claws. Black-footed Ferrets are slender animals weighing 700 to 1,125 grams (1.5 to 2.5 pounds). They are wiry mammals, and are 45 to 60 centimeters (18 to 24 inches) long, with fairly short legs. They have a black mask, black feet, and a black tipped tail. Their large front paws have well-developed claws that are used for digging. Their fur is short and yellow-buff in colour. Their bellies are lighter in colour and they have a white forehead, muzzle, and throat. Black-footed ferrets do not change colour in the winter. They have large ears and eyes but their sense of smell is probably the most important sense used for locating prey. Long-tailed weasels are sometimes mistaken for Black-footed Ferrets. Long-tailed weasels differ from Black-footed Ferrets in a number of ways. Long-tailed weasels are much smaller than Black-footed Ferrets with a length of 30 to 50 centimeters (12 to 20 inches) and a weight of 200 to 340 grams (0.44 to 0.75 pounds). Weasels are lighter in colour and the only dark spot on the body is a black spot on the tip of their tail. In the winter, the fur of the long-tailed weasel turns white. Status: The Black-footed Ferret was listed as extirpated in 1978, by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). There are only three species of ferrets in the world and the Black-footed Ferret is the only one native to North America. The historic distribution of the animal is not well known in Canada, but many people believe that it is closely linked to its primary food source, the black-tailed prairie dog (Cynomys ludovicianus). Black-tailed prairie dogs are the only species of prairie dogs in Canada and are found only in Saskatchewan. There are currently 21 museum specimens of Black-footed Ferrets taken in Canada and 20 were collected in Saskatchewan. The historic range in the United States included Arizona, Colorado, Kansas, Montana, Nebraska, New Mexico, North Dakota, South Dakota, Oklahoma, Texas, Utah, and Wyoming. North American population estimates for the Black-footed Ferret in 1900 ranged from 500,000 to one million. In 1981, the Black-footed Ferret was considered extinct until a small population was discovered near Meeteetse, Wyoming. Recovery teams in Meeteetse, Montana, South Dakota, and Arizona are currently trying to reintroduce the Black-footed Ferret to the wild. Today the Black-footed Ferret is regarded as possibly the most endangered mammal in North America. There is currently a captive population of more than 400 ferrets. Reintroducing the species into the wild has proven to be a difficult task. Range Map (Historic Range and Last Known Wild Population of the Black-footed Ferret adapted from Ministry of Natural Resources, Ontario. 1987) Habitat: The Black-footed Ferret’s habitat consisted of grasslands throughout the Great Plains of the United States, Saskatchewan and Alberta. Ferrets are found almost exclusively with prairie dogs and rely on them for food and shelter. Black-footed Ferrets use abandoned prairie dog burrows for dens. They stay underground as much as possible to avoid their natural predators which are hawks, bobcats, owls, badgers and coyotes. Ferrets are predators themselves and 90 per cent of their diet is made up of prairie dogs. They also eat mice, rats, ground squirrels, rabbits, birds and insects. The last known wild population of Black-footed Ferrets had an estimated density of one adult ferret per 40 to 60 hectares (99 to 148 acres) of habitat containing white-tailed prairie dogs (Cynomys leucurus). Black-tailed prairie dogs occur in higher densities than white-tailed prairie dogs. An adult Black-footed ferret may only require 12 to 20 hectares (30 to 50 acres) of ideal habitat containing black-tailed prairie dogs. Life Cycle: Black-footed Ferrets are solitary animals except for a few times during the year. Adults come together for a brief time in spring to breed and females are with their young, or kits, until they are able to fend for themselves. Breeding occurs from March to May and the young are born after 43 to 45 days. The kits are born helpless and blind. Females have one litter a year of between one to five kits but there can be up to nine kits. The young are raised entirely by their mother. By the fall, the kits begin to live on their own. Black-footed Ferrets are nocturnal animals but may also be somewhat active in the day. Ferrets hunt at night while prairie dogs are asleep. They search prairie dog burrows until they find their prey and then attack it using a throat hold. Adult prairie dogs can weigh up to 1,600 grams (3.5 pounds) and are known to put up a good fight. Attacking ferrets are often left with various bites, scratches and cuts. Some prairie dogs are even too large for a ferret to handle. The life expectancy for a ferret in the wild is less than five years and the highest mortality rate occurs in ferrets less than one year old. Limiting Factors: The decline of the Black-footed Ferret appears to be directly related to the extermination of prairie dogs. The primary prey for the Black-footed Ferret has been affected by agricultural practices. Habitat disruption, poisoning, trapping and hunting are all common practices to try to combat prairie dogs. As farming expanded, usable habitat for both species was ploughed under. The prairie dog habitat was reduced by 98 per cent and the ferret habitat disappeared with it. Ferrets were indirectly poisoned after eating prairie dogs that were poisoned. Black-footed Ferrets are also very susceptible to disease. Canine distemper and sylvatic plague are fatal to ferrets that become infected. Canine distemper is a virus carried by all canines and sylvatic plague is carried by prairie dogs. Both diseases threatened to cause the extinction of the Black-footed Ferret in 1986 and caused the last known wild ferret to be brought into captivity in 1987. Recovery Efforts: In Canada, recovery efforts are presently on hold. The recovery team is currently studying prairie dog populations to determine if there are sufficient numbers to sustain a viable population of Black-footed Ferrets. Currently, the population of black-tailed prairie dogs in southwestern Saskatchewan appears to be too small to reintroduce and maintain a population of Black-footed Ferrets. Canada is currently participating in a captive breeding program at the Metro Toronto Zoo. Since 1994, 21 captive bred ferrets have been sent to Wyoming where a release program is under way. In the United States, recovery efforts began shortly after the last wild population of Black-footed Ferrets was discovered. This population was studied for a few years until 1985 when canine distemper threatened the extinction of the species in the wild. By the time any action was taken to rescue the remaining ferrets, only 18 could be saved and were taken into captivity. These ferrets were taken to the Sybille facility in Wyoming where a captive breeding program was established. The breeding program was fairly successful. Currently, eight captive breeding programs are involved, including the Metro Toronto Zoo. In the fall of 1991, the first Black-footed Ferrets were reintroduced to the wild at Wyoming’s Shirley Basin. Since then, ferrets have been reintroduced in South Dakota, Montana and Arizona. It is estimated that South Dakota and Montana have 20 ferrets each. The Shirley Basin site has not done as well. It is believed that a few ferrets still remain there, but sylvatic plague has infected the prairie dog population and numbers of both species are declining. The reintroduction of Black-footed Ferrets to the wild is proving to be a difficult task for all recovery sites. Ferrets face many dangers in the wild and captive born ferrets fall easy prey to predators such as coyotes and badgers. In the United States, recovery teams are currently working on new release methods to help captive born ferrets adjust to life in the wild. The team hopes that the new release methods will improve the recovery of Black-footed Ferrets in the wild. The current U.S. recovery plan calls for 10 or more self-sustaining populations to be established. Each population should consist of 30 or more breeding pairs with a total population of at least 1,500 ferrets. Biologists hope to reach this goal by 2010 at which time the Black-footed Ferret could be downlisted from Endangered to Threatened. Any sightings of Black-footed Ferret should be reported to: the Fish and Wildlife Branch at 1-306-787-2314 Selected References: Please contact your local library or visit the internet sites below for more information on the Black-footed Ferret. Environment Canada. 1998. Black-footed Ferret (Mustela nigripes). [Online] http://www.speciesatrisk.gc.ca/species/search/SearchDetail_e.cfm?SpeciesID=138 Ministry of Natural Resources, Ontario. 1987. Wild furbearer management and conservation in North America. Ministry of Natural Resources at Whitney Block, Queen’s Park, Toronto, Ontario, Canada. U.S. Fish and Wildlife. 1996. As goes the prairie dog, so goes the ferret. [Online] Wyoming Game and Fish Department. 1997. Black-footed ferret. [Online] |