Mustela nigripesblack-footed ferret

Geographic Range

Historically, Mustela nigripes ranged throughout the interior regions of North America, from southern Canada to northern Mexico. Mustela nigripes is the only ferret that is native to North America. Today, Mustela nigripes exists in the wild in three locations, northeastern Montana, western South Dakota, and southeastern Wyoming. All three locations are sites where they have been reintroduced after the original populations were extirpated. Mustela nigripes populations also exist in seven zoos and breeding facilities (Massicot 2000, Wilson & Ruff 1999, Nowak 1991, Hillman & Clark 1980).


Black-footed ferrets can be found in the short or middle grass prairies and rolling hills of North America. Each ferret typically needs about 100-120 acres of space upon which to forage for food. They live within the abandoned burrows of prairie dogs and use these complex underground tunnels for shelter and hunting. A mother with a litter of three would need approximately 140 acres to survive (Massicot 2000, Nowak 1991).

Physical Description

Female black-footed ferrets range in weight from 645 to 850 grams, while the weight of males ranges from 915 to 1,125grams. Mustela nigripes ranges in length from 380 to 600mm (head and body). In linear measurements, male black-footed ferrets are generally 10% larger than females. The fur of Mustela nigripes is yellowish-buff with pale underparts. The forehead, muzzle, and throat are white; while the feet are black. A black mask is observed around the eyes, which is well defined in young black-footed ferrets (Massicot 2000, Wilson & Ruff 1999, Nowak 1991, Hillman & Clark 1980).

  • Range mass
    645 to 1125 g
    22.73 to 39.65 oz


Females become sexually mature at the age of one year. The breeding season typically extends through March and April. The gestation period ranges from 35-45 days. Litters range from 1-6 young, with an average litter size of 3.5 young. Young remain in the burrow for about 42 days before coming aboveground. During the summer months of July and August females and their young stay together, in the fall they separate as the young ferrets reach their independence. Females ferrets have three pairs of mammae. Ferrets are sexually dimorphic, with males being larger than the female. During the mating season, females aggressively solicit males. Black-footed ferrets exhibit a phenomenon known as "delayed implantation," in which the fertilized egg does not start developing until conditions are appropriate for gestation (Massicot 2000, Wilson & Ruff 1999, Nowak 1991, Hillman & Clark 1980).

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • Average number of offspring
  • Average gestation period
    43 days
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    365 days
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    365 days



Mustela nigripes is nocturnal. Black-footed ferrets are active mostly during the night, with peak hours around dusk. Ferrets reduce their activity levels in the winter, sometimes remaining underground for up to a week. Black-footed ferrets are subterranean animals that utilize prairie dog burrows for travel and shelter. Ferrets are solitary, except during the breeding season, and there is no male participation in rearing of the young. Black-footed ferrets are also territorial and will actively defend territories against other same-sex competitors. Black-footed ferrets are considered an alert, agile, and curious mammal, and are known to exhibit keen senses of smell, sight, and hearing. They rely on olfactory communication (urination, defecation) to maintain their dominance hierarchies and to aid in retracing tracks during night travel. Black-footed ferrets are vocal mammals that chatter and hiss in the wild when they have been scared or frightened (Massicot 2000, Wilson & Ruff 1999, Nowak 1991, Hillman & Clark 1980).

Communication and Perception

Food Habits

Black-footed ferrets rely primarily on prairie dogs for food. However, they sometimes eat mice, ground squirrels, and other small animals. Normally, over 90% of a black-footed ferret's diet consists of prairie dogs, which are hunted and killed within their burrows. A black-footed ferret typically consumes between 50-70 grams of meat per day. It has been observed that black-footed ferrets only kill enough to eat, and caches of stored food are not usually found (Massicot 2000, Wilson & Ruff 1999, Nowak 1991, Hillman & Clark 1980).

Economic Importance for Humans: Positive

Black-footed ferrets help control populations of prairie dogs, which are sometimes seen as pests because of their burrowing activities and because they as as reservoirs for zoonotic diseases such as bubonic plaque.

Economic Importance for Humans: Negative

Black-footed ferrets are often seen as pests by ranchers. The tunnel systems that are used by ferrets and prairie dogs cause holes in the the earth in the grazing lands of cattle. Unfortunate livestock sometimes step into these holes and become lame, after which they must be destroyed.

Conservation Status

Considered to be North America's rarest mammal. Black-footed ferrets have been heavily impacted by the extermination of prairie dogs. Ranchers poisoned prairie dogs because of destruction (tunneling and foraging) to rangelands. With the disappearance of prairie dogs, so too went black-footed ferrets. Numbers dropped to an astounding 31 in 1985, and by 1987 they were extinct in the wild. Of the original 100 million acres of black-footed ferret habitat, only 2 million acres remain. Many ferrets were also killed by a canine distemper epidemic that spread through the American grasslands.

Captive breeding and reintroduction programs are underway in several locations throughtout North America (Massicot 2000)


Ken Briercheck (author), University of Michigan-Ann Arbor, Rebecca Ann Csomos (author), University of Michigan-Ann Arbor, Cynthia Sims Parr (editor), University of Michigan-Ann Arbor.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


uses touch to communicate

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.


A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.


Hillman, C., T. Clark. April 1980. Mammalian Species No. 126: Mustela nigripes. USA: American Society of Mammalogists.

Massicot, P. 2000. "Animal Info - Black-footed Ferret" (On-line). Accessed 17 May 2000 at

Nowak, R. 1991. Walker's Mammals of the World. USA: Johns Hopkins University Press.

Wilson, D., S. Ruff. 1999. The Smithsonian Book of North American Mammals. USA: Smithsonian Institution Press.