Ferret, a carnivorous mammal related to the weasel. The domestic ferret, when mature, is about 19 inches (48 cm) long, including a 5-inch (13-cm) tail. It has a slender body, short legs, and a flat, triangular head. It is yellowish white, sometimes brown. The domestic ferret is raised as a pet and for use in driving rats and rabbits from their burrows. Ferrets that have escaped domestication are extremely destructive, especially to poultry.

The black-footed ferretThe black-footed ferret is native to the Great Plains of North America.

The black-footed ferret is native to the Great Plains of North America. It grows about as large as the domestic ferret. It is generally yellowish brown, and has a black band across the eyes, black feet, and a black tail tip. In the early 1900's, ranchers began poisoning the black-footed ferret's main food source, the prairie dog. As the prairie dog population declined, the black-footed ferret became very rare. In 1986, all known black-footed ferrets were taken from the wild and put in a captive breeding program, directed jointly by the Wyoming Game and Fish Department and the U.S. Fish and Wildlife Service. Since 1991, a number of ferrets bred in captivity have been released into areas where prairie dogs have reestablished themselves following the curtailment of poisoning.

Ferrets belong to the weasel family, Mustelidae. The wild ferret, of which the domestic ferret is a subspecies, is Mustela putorius; the domestic ferret is M. p. furo. (The wild ferret is often called polecat. See Polecat. The name polecat is also applied, in parts of the United States, to a related animal—the skunk.) The black-footed ferret is M. nigripes.