Black-tailed prairie dogs are members of the Sciuridae or squirrel family, closely related to ground squirrels, chipmunks, woodchucks and marmots. There are five different species of prairie dogs, but only the black-tailed prairie dog inhabits Devils Tower National Monument.

Prairie dogs are small, short-tailed animals with eyes and small ears set far back on their heads. Their light-brown fur blends well with the dirt of their mounds except when the animal has been blackened by burrowing into coal seams. Named for their bark-like warning call and black-tipped tail, prairie dogs average 14 to 17 inches in total length and weigh 1 to 3 pounds. With short, muscular legs and long-nailed toes on their front and hind feet, they are well equipped for a burrowing lifestyle.

A prairie dog colony or "town" consists of a large number of closely spaced burrows, each comprising an elaborate network of interconnecting tunnels and multiple entrance holes that provide escape routes from pursuing predators. The primary prairie dog social unit is the "coterie," an acre or so of territory with 50 to 60 burrow entrances that is occupied by a single family group. A coterie typically consists of one adult male, several adult females, and their offspring. Members of a coterie are a closely knit group, recognizing each other by an identifying kiss or sniff. Their cohesiveness is maintained by the cooperative activities of raising young, constructing burrows, grooming, playing and defending the coterie territory.

Prairie dogs feed primarily on plants and grasses high in moisture content and nutritive value to supply their needs for water and energy. And build up large stores of body fat to carry them through the autumn and winter months. Unlike most other members of their family, black-tailed prairie dogs do not hibernate. They may remain underground for several days during periods of harsh weather, but a return to milder winter conditions will find their towns bustling with activity.