Mustela nigripes Linnaeus 1758

49. Black-footed Ferret Mustela nigripes French: Putois d’Amérique / German: Schwarzful3iltis / Spanish: Turon patinegro Taxonomy. Putorius nigripes Audubon & Bachman, 1851, Wyoming, USA. Monotypic. Distribution. Great Plains of USA (Arizona, Colorado, Kansas, Montana, New Mexico, South Dakota, Utah & Wyoming) and N Mexico. Descriptive notes. Head-body 40-50 cm, tail 11.4-15 cm; weight 964-1078 g (males), 764-854 g (females), adult males are larger than females. The Black-footed Ferret has a long body and short limbs. The pelage is yellowish-buff or beige with black hairs throughout; the underparts are paler. The forehead, muzzle, and throat are nearly white. The top of the head and middle of the back are brown. There is a distinctive, broad, horizontal black stripe across the face. The feet and terminal fourth of the tail are black. There are three pairs of mammae. Dental formula: 13/3, C 1/1, P3/3,M1/2=34 Habitat. Black-footed Ferrets are found on short/mid-grass prairies and semi-arid grasslands, in close association with prairie dogs. Food and Feeding. Black-footed Ferrets specialize in preying on prairie dogs (Cynomys), which they hunt by pursuing them inside their burrow systems. Occasionally, they may also eat other small mammals, such as microtine rodents and ground squirrels. One scat study revealed a diet that comprised 87% White-tailed Prairie Dogs (Cynomys gunnisoni), 6% mice, and 3% lagomorphs. Activity pattern. Primarily nocturnal, although daytime activity is not uncommon. Black-footed Ferrets are active throughout the year and continue to hunt prairie dogs during the winter, even though they are in hibernation. Prairie dog burrows are used as den/rest sites and may be modified for their own use. Movements, Home range and Social organization. Black-footed Ferrets are solitary, except during the breeding season. They seldom move from one prairie dog colony to another. The average nightly movement during winter is 1406 m. The average prairie dog town size occupied by a Black-footed Ferret is 8 ha, but the average size occupied by females with young is 36 ha (range = 10-120 ha). The mean distance between two towns occupied by Black-footed Ferrets is 5- 4 km. Population density in Wyoming was estimated to be one ferret per 50 ha of prairie dog colonies. Breeding. Mating occurs in March and April. Gestation lasts 42-45 days and births occur in May and June. Litter size can range from one to six; the average is three. The young emerge from the burrow in early July and separate from the mother in September or early October. Young males disperse a considerable distance, but young females often remain in the vicinity of their mother’s territory. Sexual maturity is attained by one year. Status and Conservation. Listed as Extinct in the Wild in 1996, but the success of conservation measures has changed their status to Endangered in The IUCN Red List. The Black-footed Ferret may once have been common in southern Canada (Alberta, and Saskatchewan), west-central USA (Montana, North Dakota, South Dakota, Nebraska, Wyoming, Arizona, and Texas), and northern Mexico. Destruction of prairie dog colonies for the sake of agriculture led to a decline in Black-footed Ferret numbers and eventually they became so rare that many people considered them to be extinct. However, unconfirmed sigh things continued from several states, and in 1981 a small population of Black-footed Ferrets was discovered in Wyoming. Intensive field studies were initiated, and byJuly 1984, the population was estimated to contain 129 individuals. However, the number of ferrets then began to fall, apparently due to a decline in their prairie dog prey; also, canine distemper was somehow introduced into the wild population. By 1987, the remaining 18 individuals were brought into captivity to start a breeding program. By 1991, there were 180 individuals in captivity and 49 ferrets were released into south-eastern Wyoming; 91 more were released in 1992, and another 48 in 1993. Most of these animals are thought to have died, but some are known to have survived and reproduced; at least six litters were born in the wild in 1993. Additional reintroductions were carried out in Montana, South Dakota, and Arizona. Today, they are known from 18 reintroduction efforts, only three of which are self sustaining. These self-sustaining populations are in South Dakota and Wyoming; four populations of limited success are in Arizona, Colorado, South Dakota, and Utah; eight populations recently introduced are in Arizona, Kansas, Montana, New Mexico, South Dakota, and Mexico; and three other declining or extirpated populations are in Montana. The current status of this species is still extremely precarious. Bibliography. Biggins et al. (1986), Campbell et al. (1987), Hillman & Clark (1980), IUCN (2008), Svendsen (2003), Vargas & Anderson (1998), Wozencraft (2005), Young et al. (2001).

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