The Black-footed Ferret Recovery Implementation Team

Captive Black-footed Ferrets in Col

Black-footed ferrets (Mustela nigripes) are one of the most endangered mammals in the world. They are a member of a large group of mammals known as mustelids, or musk-producing animals. Sixty-four species of mustelids live throughout the world, except on the continents of Australia and Antarctica. Mustelids range in size from the least weasel, which weighs barely 1-2 ounces, to the sea otter, which may weigh over 100 pounds. Most mustelids have long bodies and short legs, well-developed claws, short, rounded ears, and scent glands under the tail. Their large skulls and strong jaws and teeth are adapted for eating meat. Some well-known members of the mustelid family include mink, skunks, badgers, martens, fishers, weasels, stoats, polecats, wolverines, and the European, or domestic ferret, sold in pet stores.

Black-footed ferrets are 18 to 24 inches (46-61 cm) long, including a 5 to 6 inch (13-15 cm) tail. They weigh only one-and-a-half to two-and-one-half pounds (0.68 – 1.13 kg), with males slightly larger than females. Black-footed ferrets are well adapted to their prairie environment. Their color and markings blend so well with grassland soils and plants that they are hard to detect until they move. They are obligate carnivores of the prairie dog for food and shelter. They are a slender, wiry animal with a black face mask, black feet, and a black-tipped tail. Their short, sleek fur is a yellow-buff color, lighter on the belly and nearly white on the forehead, muzzle, and throat. They have short legs with large front paws, and claws developed for digging. The ferret's large ears and eyes suggest they have acute hearing and sight, but smell is probably their most important sense for hunting prey underground in the dark. There are three ferret species worldwide but the black-footed ferret is the only one indigenous to North America.

Click above to view a movie
of a Mom and Kit playing.

Cultural Significance

Native Americans knew of the close association between prairie dogs and ferrets, all of whom have coexisted for many thousands of years. Skeletons of both ferrets and prairie dogs have been found in camps occupied by prehistoric Indians, and various tribes had different beliefs about ferrets. Pispiza etopta sapa, meaning "black-faced prairie dog" is the Sioux Indian name for the black-footed ferret. The Pawnees call it "ground dog" and gave the ferrets special powers in their stories. The Navajo Nation refers to the ferret as Dlo ii liz-hinii and used ferret body parts and skins for medicinal purposes and ceremonial adornments. The Cheyenne and Blackfeet tribes decorated chiefs' headdresses with their furs. The Hualapai Indians, who traditionally regard all living things that come out at night as sacred, call the black-footed ferret Na-math. The Crow used ferret skins in sacred ceremonies as medicine bundles. These skins, stuffed and decorated with leather, cloth, bells and feathers can be seen in several museums in the West.

Behavior

The nocturnal black-footed
ferret in South Dakota
Photo credits: Travis Livieri

Black-footed ferrets are primarily nocturnal, making direct observation difficult. Most of their daytime activity is limited to the first few hours following sunrise. They spend most of their time underground in prairie dog burrows, typically spending only a few minutes aboveground each day to hunt or find new burrows or, in spring, mates. In burrows they sleep, cache their food, escape from predators and harsh weather, and give birth to their young. Ferrets do not hibernate, but in winter, the amount of time they are active and the distances they travel decrease substantially. They have been found to remain underground in the same burrow system for a week at a time in winter. In contrast, one ferret was observed traveling over six miles in one night during autumn. Males are more active than females and distances traveled by males tend to be about double that of females.


	Click the play button to see a video of a ferret dance.

Black-footed ferrets are very playful, especially as juveniles. Young at play will wrestle, arch their backs and hop backward with their mouths wide open--the "ferret dance".Black-footed ferrets are very vocal. A loud chatter is used as an alarm call. Click here to hear a ferret chatter. A hiss is used to show agitation or fear, and whimpering sounds are used by females to encourage the young to follow. Male ferrets often "chortle" to females during breeding.

Reproduction

Four-day-old black-footed ferret kits

Black-footed ferrets lead solitary lives except during the breeding season or when females are caring for young. Breeding activity generally occurs in March and April, and after a gestation period of 41 to 43 days, a litter of kits is born. The average litter size is three to four young, but single kits, as well as litters of nine or ten have been recorded. Only the female cares for the young. The kits are born blind and helpless, weighing only 5 to 9 grams at birth, with thin, white hair covering their bodies. Their dark markings appear at about 3 weeks of age, and young kits begin to open their eyes about 35 days after birth. Black-footed ferret kits develop very rapidly and become increasingly active after their eyes open. (picture of male & female together (will send)

Black-footed ferret mom with kits

Kits are about three-quarters grown by July when they first venture above ground. Long after they stop nursing, they depend on their mother for meals of meat. By late summer, the female leaves her kits in separate burrows during the day and gathers them together at night to hunt. Eventually, the young begin to hunt alone, and by September are usually independent and solitary. Both male and female ferrets become sexually mature at one year of age, and their peak reproductive period is about three to four years.

Specialization

Black-footed ferrets are highly specialized. They are what is called an obligate carnivore, meaning that they specialize in eating one type of animal. In their case, it is prairie dogs. In the evolutionary past this was a very good survival strategy because prairie dogs were plentiful and their burrows provided shelter from harsh weather and predators. However, today due to human activities, their unique survival strategy has become a limitation to their survival.

Threats

One day’s kill in Arizona

Loss of habitat is the primary reason black-footed ferrets remain near the brink of extinction. Conversion of native grasslands to intensive agricultural uses, widespread prairie dog eradication programs, and the fatal non-native disease plague have reduced ferret habitat to less than two percent of what once existed. Remaining habitat is now fragmented, with prairie dog towns separated by expanses of cropland and human development. Three species of prairie dog occurred across 500 million acres, an area the size of six Texas sized states, and physically occupied 100 million acres (Hilton et al, 1978). Prairie dogs once moved across the landscape over decades and centuries in response to drought, fire, bison grazing and other factors. Now prairie dog colonies are small and isolated with restricted movement and connectivity. Many other sensitive species such as burrowing owls, mountain plovers, (non-listed) golden eagles, swift fox, and ferruginous hawks are strongly linked to this habitat for their survival. Some species may follow the ferret's fate, and may soon require further conservation efforts to ensure their survival.

Young badger
Photo credits: Travis Livieri

Black-footed ferrets also face threats in the wild from predators and disease. Coyotes, great-horned owls, golden eagles, prairie falcons, badgers, bobcats and foxes all prey on ferrets. Several diseases affect black-footed ferrets, the most serious being canine distemper and sylvatic plague.

Canine distemper is thought to always be fatal to ferrets and is spread by other animals that frequent prairie dog towns, such as coyotes and badgers. Sylvatic plague, spread by fleas, is akin to the bubonic plague that devastated humans in Europe in the Middle Ages. Both ferrets and prairie dogs are highly susceptible to plague, and entire dog towns can be eliminated quickly. Ferrets are also susceptible to other diseases, including rabies, tularemia and human influenza, but these are not considered serious threats.