Biologists consider black-footed ferrets 

to be the most endangered mammal in the

United States. Recently, however, thanks 

to aggressive captive-breeding and

reintroduction programs, much progress 

has been made toward recovering the 

ferret population.

Black-footed ferrets are members of the

weasel family (Mustelidae), a distinction

they share with weasels, martens, fishers,

otters, minks, wolverines and skunks.

Larger than weasels, black-footed ferrets

are long, slender-bodied animals similar in

size to a mink. They are characterized by a

brownish-black mask across the face, a

brownish head, black feet and legs, and a

black tip on the tail. Ferrets’ short, buffcolored fur becomes lighter on the underside

of their bodies. The middle of the back has

brown-tipped guard hairs that create the

appearance of a dark saddle.

Black-footed ferrets may look like the

ferrets found in pet stores but they are

actually a different species. Both belong to

the weasel family but ferrets sold as pets

evolved in Europe, while endangered blackfooted ferrets evolved in North America.

Possibly black-footed ferrets never were

abundant, but their underground nocturnal

habits make it difficult for biologists to know

for certain. First described by naturalists

John Audubon and James Bachman in 1851,

black-footed ferrets were not sighted again

for 25 years.

Ferrets once were found throughout the

Great Plains, from Texas to southern

Saskatchewan, Canada. Their range

extended from the Rocky Mountains east

through the Dakotas and south through

Nebraska, Kansas, Oklahoma, Texas, New

Mexico and Arizona. Where prairie dogs

were found, so were black-footed ferrets.

Ferrets eat prairie dogs and live in prairie

dogs’ burrows.

Typical wild ferret behavior revolves

around prairie dog towns. Wild ferrets

hunt prairie dogs at night but occasionally

they are active above ground during the

day. This is especially true of the female

ferrets hunting to feed their young. In

search of prey, they move along in loping

bounds from one burrow to the next. When

they make a kill, ferrets may drag prairie

dogs some distance to a home burrow to

devour below ground or to burrows in

which they have their young.

Black-footed ferrets produce about four or

five young once each year. Born in May or

June, the young do not come above ground

until they are six weeks old. Mothers and

young remain together until about midAugust. At that time, females begin to

separate the siblings into different burrows.

From August through early September the

young become increasingly solitary. By early

October they are able to take care of

themselves.

Main causes of the decline in the ferret

population included habitat conversion for

farming; efforts to eliminate prairie dogs,

which competed with livestock for available

prairie forage; and the sylvatic plague, a

disease which wiped out large numbers of

ferrets.

The U.S. Fish and Wildlife Service listed

black-footed ferrets as endangered in 1967

under a precursor to the Endangered

Species Act of 1973. Endangered means a

species is considered in danger of becoming

extinct in all or a significant portion of its

range; the less dire designation of

threatened means a species is likely to

become endangered within the foreseeable

future throughout all or a significant portion

of its range.

By 1972, biologists believed black-footed

ferrets to be extinct. From 1972 until 1981,

although many ferret sightings were

reported, the only documented population

was found in the 1970s in South Dakota.

Then in 1981, a dog killed an unusual animal

on a ranch in Wyoming. The rancher took it

to a taxidermist who recognized it as a blackBlack-footed ferret

Mustela nigripes

The black-footed ferret probably never was

abundant, but its underground, nocturnal

habits make it difficult for biologists to know

for certain. The ferret’s 

primary food source is 

the prairie dog, and 

ferrets live in the 

prairie dog’s burrow.

U.S. Fish & Wildlife Service
footed ferret. This led to the discovery of a

small ferret population near Meeteetse,

Wyoming, in 1981. The population increased

from 1981 through 1984. At its peak in 1984,

nearly 130 ferrets were counted.

In October 1985, the Wyoming Game and

Fish Department, in cooperation with the

Fish and Wildlife Service, captured six

black-footed ferrets to start a captive

breeding population at the Department’s

Sybille Wildlife Research and Conservation

Education Center near Wheatland,

Wyoming (now operated by the Fish and

Wildlife Service as the National Black-footed

Ferret Conservation Center). During the fall

of 1986 and the spring of 1987 the last known

wild black-footed ferrets were taken from

the wild and placed in captive breeding

facilities. This captive population now has

increased to approximately 300 black-footed

ferrets.

The goal of the captive breeding program

is to establish 240 breeding adults in

captivity while continuing to return ferrets

to the wild. In an effort to protect ferrets

from one catastrophic event which could

eliminate the entire experimental wild

population, the captive population was

divided. In addition to the Ferret

Conservation Center colony, breeding

populations have been established at the

National Zoo’s Conservation and Research

Center in Front Royal, Virginia; the Henry

Doorly Zoo in Omaha, Nebraska; the

Cheyenne Mountain Zoological Park in

Colorado Springs, Colorado; the Phoenix

Zoo in Phoenix, Arizona; and the Louisville

Zoological Garden in Louisville, Kentucky.

The future looks brighter for black-footed

ferrets. Reintroduction began in 1991 with

the release of a group of ferrets into the

Shirley Basin of Wyoming. Since then, 228

ferrets have been released there. While

there is a high mortality rate among these

captive-born animals, two litters born in the

wild indicate that the reintroduced

population has taken hold. Biologists

stopped releasing ferrets in the Shirley

Basin after 1995 because of disease concerns

and decreasing habitat.

Two new reintroduction sites in Montana

and South Dakota were identified and

biologists released 40 to 50 ferrets per year

on these sites between 1994 and 1997.

Biologists hope the populations on these

sites will be self-sustaining after 1998. So far

reintroduction efforts in those two states

have met with some success. In 1997, twelve

litters of ferrets were born in the wild in

Montana and reintroduced ferrets in South

Dakota had an 80 percent survival rate.

In 1996 and 1997, biologists identified

suitable release sites in areas in Utah,

Colorado and Arizona. Sixty-five ferrets

have been released in the Aubrey Valley in

northwest Arizona since March, 1996. Some

of the released ferrets have already given

birth in the wild, and biologists plan to

release more ferrets in the same area.

To be considered suitable for ferret

reintroduction, an area must be very large

and relatively free of diseases, particularly

canine distemper and plague, that could wipe

out an entire colony. And the public must

support the presence of black-footed ferrets.

To this end, biologists work closely with

landowners to work out compromises that

benefit the ferret and landowners.

Reintroduced black-footed ferret

populations have been designated “nonessential experimental” populations under

the Endangered Species Act. This

designation allows federal, state and tribal

resource managers, and private citizens,

more flexibility in managing new

populations. The Service can develop special

management regulations which are more

flexible than the rules for species listed as

endangered, encouraging cooperation in the

recovery effort by landowners, agencies and

recreation interests. The “non-essential,

experimental” designation also allows land

uses such as forest management,

agricultural practices, sport-hunting and

non-consumptive outdoor recreation.

National goals to recover the species are to

establish ten free-ranging populations of

black-footed ferrets, spread over the widest

possible area within their former range.

Each of these populations will have 30 or

more breeding adults. It is hoped that 1,500

free-ranging black-footed ferrets will be

established in the wild by the year 2010.

If these and future efforts are successful,

black-footed ferrets may soon be playing an

important role in the dynamics of wild

prairie dog towns once again.

U.S. Fish & Wildlife Service

1 800/344 WILD

http://www.fws.gov

August 1998

Black-footed ferrets hunt prairie dogs at

night, but occasionally they are active above

ground during the day. In search of prey,

they move along in loping bounds from one

burrow to the next.