Black-tailed prairie dogs (Cynomys ludovicianus) once ranged the Great Plains from southern Saskatchewan to northern Mexico. Originally named "petits chiens," or "little dogs," by early French explorers, these highly social animals are not really dogs, but rodents. 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 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. The dominant male is typically the most active in the defense of the coterie, patrolling its invisible borders and challenging all comers. Prairie dogs warn of territorial trespassers from adjacent coteries or approaching danger by emitting a series of "barks," which sound more like high-pitched squeaks. Specific threats are associated with distinctive vocalization patterns that serve to alert all residents of a town to the common threat.
Prairie dogs feed primarily on plants, selecting forbs (flowering plants not shrubs or trees) and grasses high in moisture content and nutritive value to supply their needs for water and energy. Grasses, far less resistant to foraging pressure than forbs, quickly disappear from the town, which takes on a barren and overgrazed appearance. The open, closely-cropped terrain promotes easier social contacts and enables the collective "thousand eyes" of the residents to better spot approaching danger. With reduced competition from grass species, forbs begin to increase in abundance, and soon are joined by invading "weedy" plants like thistle and sage. Pronghorn and deer are attracted to feed in this modified community, their trampling further compacts the soil to maintain forb growth. Varying its diet so as not to feed on one species of plant exclusively, the prairie dog practices its own brand of crop rotation. Forage pressure on preferred plants is kept at tolerable levels and the community thrives. This balance may be upset by climatic changes that, if persistent, could force prairie dogs to abandon a town. Recolonization may recur later when a more favorable environment has allowed the former plant community to recover.
Prairie dogs build up large stores of body fat to carry them through the fall 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.
Mating occurs from March to early April. After a month-long gestation period, the female bears a litter of one to six young. Born blind and hairless, the pups stay in the burrow for about six weeks while they develop fully. Emerging from the burrow, young prairie dogs are initially protected by their mothers. Weaning occurs shortly thereafter, when the pups have begun to forage for themselves. Most animals spend their brief five- to seven-year existence within the coteries of a single town.
Plump prairie dogs are an important component of the diet of many animals. Badgers, coyotes, foxes, bobcats, golden eagles.and various hawks all take their toll; rattlesnakes and bullsnakes occasionally prey on the young. Prairie dogs rely on their excellent hearing and vision to avoid these predators. From their vantage point atop the burrow mound, they can listen and scan the sky and prairie for danger. Upon spotting an enemy and announcing its presence to the rest of the town, the prairie dog dives into its burrow, emerging to give an "all clear" call when the danger has passed.
The number of prairie dogs a given area can support at any one time is based on the prevailing relations between a number of interacting environmental factors, one of which is predation. Other environmental pressures--weather changes, shifts in the availability of edible plants, outbreaks of disease -- all affect the size of prairie dog populations. If, for example, predators fail to keep the numbers of prairie dogs in check, a population "boom" will occur. The environmental balance is inevitably restored by a subsequent population "bust," animals dying in large numbers from disease or starvation brought about by overcrowding and exhaustion of the town's food resources.
The prairie dog was once a major component of Great Plains life. Vast prairie dog towns stretched for miles across the open plains. In 1901, scientists surveyed a single Texas "dog town" that covered an area of 25,000 square miles and contained an estimated 400,000,000 prairie dogs. But this town and others were already under sentences of death. Prairie dog burrows proved dangerous for horses and wandering livestock and most ranchers were convinced that prairie dogs were destroying rangelands and competing with cattle for food. Reluctance to acknowledge that poor livestock management practices and the wholesale elimination of prairie dog predators were at least contributing factors to the problem prompted extensive poisoning programs. These measures virtually eradicated the prairie dog and many of its predators, chief among them the black-footed ferret. Formerly the prairie dog's most dangerous enemy, ferret numbers have only recently been raised through captive breeding programs to a level where small populations are now being released back into the wild. Today, scattered populations of prairie dogs are found mainly in protected areas such as state and national parks, monuments, grasslands, and wildlife refuges.
Warning: Please do not feed prairie dogs. Human food is hard for prairie dogs to digest and often contains additives that can kill them. Remember, too, that prairie dogs are wild animals and can inflict a painful bite. They may also be host to lice and to fleas that can transmit bubonic plague to humans.
Did You Know?
Porcupines spend a good deal of their lives stripping off the outer bark of trees to expose and eat the cambian layer. You can see many examples of this at Devils Tower when you walk along the Tower Trail.