Rattlesnakes are quite plenty, living in the deserted holes, and the latter are also the homes of the little burrowing owls. They 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 Theodore Roosevelt National Park.
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. With short, muscular legs and long-nailed toes on their front and hind feet, they are well equipped for a burrowing lifestyle. 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.