Friday, September 14, 2012

Black Footed Ferret

Once classified as Extinct in the Wild, the black-footed ferret (Mustela nigripes) is one of the world's rarest mammals and the only ferret native to North America. This slender animal has a yellowish coloured coat, pale under parts, and a dark tail tip and black feet. The muzzle, throat and forehead are white and there is a black mask around the eyes. As with most members of the genus Mustela, the males are larger and much heavier than female. The legs are short and the large front paws are armed with claws for digging.

Did You Know
            Ferrets are nocturnal, sleeping up to 21 hours per day and hunting prairie dogs primarily during the night.

Size relative to a 6-ft human

Scientific Classification
Mustela nigripes

Other Names
Black-footed Ferret
Putois À Pieds Noirs
Turón Patinegro Americano

          The black-footed ferret is classified as Endangered (EN) by the IUCN Red List (1), and listed on Appendix I of CITES.

           At present there are no known non-introduced wild populations, and only three of the populations contain mature individuals which were born in the wild. This species nearly went extinct in the late 1980s and existing populations are the success of massive efforts to reintroduce the species back to its native habitat.

            Since 1987, over 6,000 ferret kits have been produced through captive breeding and since 1991, over 2,000 ferrets have been released at 18 sites. All populations are sampled and counted two times a year as part of a management and recovery protocol.

         Black-footed ferrets are limited to open habitat, the same habitat used by prairie dogs: grasslands, steppe, and shrub steppe. It depends largely on prairie dogs: ferrets prey on prairie dogs and utilize their burrows for shelter and denning. It has been estimated that about 40-60 hectares of prairie dog colony are needed to support one ferret.

            Historically, black-footed ferrets were found throughout the Great Plains, mountain basins, and semiarid grasslands of west central North America - from southern Canada to northern Mexico wherever its prey, prairie dogs, were located. The species was extirpated from most of its former range mainly as a result of prairie dog control programs and sylvatic plague, an exotic disease which was introduced to wild population. Today, they are known from 18 reintroduction efforts, only 3 of which are self-sustaining. The three self-sustaining populations are in South Dakota and Wyoming.           

           The black-footed ferret is an alert, agile, nocturnal animal, which spends the day in prairie dog burrows. More than 90 percent of the diet consists of prairie dogs, which are attacked whilst they sleep in their burrows, although mice, ground squirrels, voles and other small mammals are also taken.

This species is solitary, except during the breeding season, which runs from March to April. Females give birth to litters of between three to six young (known as kits), and rear their offspring without help from the male. The young, which are born blind and helpless and covered with thin white hair, stay in the burrow for about 42 days before venturing above ground, and remain with their mother until the autumn, after which time they disperse. These ferrets have excellent senses of hearing, sight and smell, and olfactory communication is very important in the maintenance of dominance hierarchies and following trails at night. Vocalizations include chattering and hissing.

           The number of black-footed ferrets plummeted in the first half of the 20th century, primarily as a result of habitat loss. Prairies have been modified for intensive agriculture and there is now less than two percent of the original ferret habitat left. The ferret's main prey, prairie dogs, was systematically poisoned in vast tracts of their habitat by a government eradication programme in the mid-1900s. Prairie dog burrows were thought to damage cropland and ferret numbers fell in direct proportion with the dramatic decline of their prey. The final threat to black-footed ferret numbers, and perhaps the most pertinent today, is disease, particularly canine distemper and plague. Plague, introduced to North America, causes even greater devastation in populations of prairie dogs and ferrets than it caused in human populations of Europe and Asia.

            Another major threat is loss of habitat for conversion of grasslands to agricultural uses; the remaining habitat is now fragmented by great expanses of cropland and human development. In addition, the genetic diversity of the present introduced population is less than 90% of that present in the species prior to their decline in the wild. This decrease in genetic diversity has led to increased inbreeding and may lead to decreased fitness due to inbreeding depression, including immune system dysfunction and reduced reproductive success.

Conservation Measures
           The black-footed ferret captive breeding program was initiated in October 1985 by the Wyoming Game and Fish Department in cooperation with the United States Fish and Wildlife Service. Eighteen black-footed ferrets were captured between 1985 and 1987 from the last-known population in Wyoming to start a captive breeding population, with the ultimate goal of reintroduction. Seven of those 18 individuals contributed unique genetic material for captive breeding and are considered founders.

           There are currently six institutions (one federal facility and five zoos) participating in the propagation program under the supervision of the United States Fish and Wildlife Service. Beginning in 1985, more than 6,000 black-footed ferrets have been born in captivity. Beginning in 1991, ferrets have been reintroduced at sites in eight Western U.S. states (Montana, South Dakota, Wyoming, Colorado, Utah, Arizona, Kansas, and New Mexico) and one site in Mexico. The species is listed on CITES Appendix I and in listed in the U.S. Endangered Species Act.



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