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. In search of prey, they move along in loping bounds from one burrow to the next.
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. 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, buff-colored 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.