prairie dog, short-tailed, ground-living rodent, genus Cynomys, of the squirrel family, closely related to the ground squirrels, chipmunks, and marmots. There are several species, found in the W United States and N Mexico. Prairie dogs, named for their barking cries, are 12 to 15 in. (30 to 36 cm) long, including the 1- to 4-in. (2.5 to 10 cm) tail, and have short, coarse, buff-colored fur. The black-tailed prairie dog, Cynomys ludovicianus, is found on the Great Plains. Members of this species live in connecting burrows, forming colonies, or "towns," which may extend many miles and include thousands of individuals. The entrances of the burrows are surrounded by cone-shaped mounds, which serve to keep out rainwater; the entrance shafts drop straight down for several feet. Prairie dogs spend much time maintaining the mounds by tamping down damp earth. They often sit upright on their haunches in rows, one animal on each mound; this behavior has given them the name "picket pins" in some regions. At any sign of danger the animals give a warning cry and duck down into the burrows. Rattlesnakes and burrowing owls sometimes live in the burrows and prey on young prairie dogs. Three species of white-tailed prairie dogs inhabit open or brushy valleys of the Rocky Mts; their burrows are usually less extensive than those of the black-tailed species. Prairie dogs feed mainly on grasses, but also eat insects; they hibernate in winter. Prairie dog towns were formerly much more common and extensive than now; some towns on the plains encompassed millions of individuals. Ranchers regard the animals as competitors for grazing lands and have destroyed them in large numbers. Prairie dogs are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Rodentia, family Sciuridae.