Animal Diversity Web

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).

• Biogeographic Regions
• nearctic
  • native

Habi­tat

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).

• Terrestrial Biomes
• savanna or grassland

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).

• Other Physical Features
• endothermic
• bilateral symmetry

• Range mass

  645 to 1125 g

  22.73 to 39.65 oz

Re­pro­duc­tion

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

  3

  AnAge

• Average gestation period

  43 days

  AnAge

• Average age at sexual or reproductive maturity (female)
  Sex: female

  365 days

  AnAge

• Average age at sexual or reproductive maturity (male)
  Sex: male

  365 days

  AnAge

Lifes­pan/Longevity

• Average lifespan
  Status: captivity

  12.0 years

  Max Planck Institute for Demographic Research

Be­hav­ior

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).

• Key Behaviors
• motile

Com­mu­ni­ca­tion and Per­cep­tion

• Perception Channels
• tactile
• chemical

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)

• IUCN Red List

  Endangered
  More information

• US Federal List

  Endangered

• CITES

  Appendix I

Con­trib­u­tors

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.

Ref­er­ences

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 http://​www.​animalinfo.​org/​species/​carnivor/​mustnigr.​htm.

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.