Abstract
The blacktail prarie dog (Cynomys ludovicianus) has evolved as a highly successful colonial herbivore with a definite role among natural prairie ecosystems (Coppock et al., 1980; McHugh, 1958). Their coloniality often creates high population densities and heavy use of vegetation (Klatt, 1971; Koford, 1958), inviting conflict with human land use. Exercising management extremes (i.e., completely exterminating prairie dog colonies or allowing the propagation of hugh populations) appears to present little difficulty. The necessary alternative of containing colonial areas and controlling population densities, however, will require nothing short of a complete understanding of prairie dog emigration ecology. Three basic types of prairie dog movement are possible: movements within towns, peripheral expansion of established towns, and long distance dispersals. The latter two categories are of most practical interest, though the amount of within group recruitment must surely exert some influence upon town expansion and dispersal. The subject has received little or no attention in the literature. Expansion of town perimeters and long distance dispersals appear as quite different phenomena. Observations on Badlands N.P. dog towns suggest that estabishment of peripheral burrows rarely occurs over 50 meters from an existing burrow system. Long distance dispersals appear, however, as less common, less successful events which bring individuals into other populations or initiate new colonies. Blacktail prairie dogs have been located over four miles from existing towns (Smith, 1958). Expansion along town peripheries has been described as both an early springtime activity (King, 1955; Koford, 1958; Smith, 1958) and an autumnal activity (Costello, 1970). Little agreement, and less data, exists upon the structure of these emigrating individuals; and only speculation is responsible for our present notions about the variables which control this movement.