This article is about the domesticated ferret. For the endangered North American species, see black-footed ferret.The ferret (Mustela putorius furo) is the domesticated form of the European polecat, a mammal belonging to the same genus as the weasel, Mustela, in the family Mustelidae. Their fur is typically brown, black, white, or mixed. They have an average length of 51 cm (20 in), including a 13 cm (5.1 in) tail, weigh about between 0.7 and 2.0 kg (1.5 and 4.4 lb), and have a natural lifespan of 7 to 10 years. Ferrets are sexually dimorphic predators, with males being substantially larger than females.
In the United States, ferrets were relatively rare pets until the 1980s. A government study by the California State Bird and Mammal Conservation Program estimated that by 1996 about 800,000 domestic ferrets were being kept as pets in the United States.