The concept of home range is an important biological phenomenon and has received considerable attention. In applying the concept to mammals Burt (1943) defined it as, "that area traversed by the individual in its normal activities of food getting, mating, and caring for young. " Later, Hayne (1949) defined a circular home range with concentric zones of variable utilization around a center of activity. Both workers emphasized the need to know the behavior patterns of the animals within their respective home ranges. The statistical evaluation initiated by Hayne (1949) has been refined to provide increasingly precise probability estimates of an animal being at any specified distance from its center of activity (Dice and Clark, 1953; Calhoun and Casby, 1958; Harrison, 1958; Burge, 1967). Recent research in social interactions of small mammal populations used the density probability function to estimate home ranges (Jorgensen, 1968a, 1968b; Speth, 1969).

Three heteromyid rodent species were studied in relation to a large dry wash in Millard County, Utah, during the summer, 1974. Data were gathered with three trapping grids and analyzed to determine if the dry wash influenced rodent movement and distribution patterns. Dipodomys ordii and Dipodomys microps were distributed non-randomly in the dry wash and adjacent habitat, but Perognathus Zongimembris seemed to be randomly distributed. Dipodomys ordii was significantly correlated with wash habitat, but D. microps was found most frequently in upland areas. Soil and vegetative differences and competition were possible causes for the observed distribution. The wash was observed as a source of dispersing young D. ordii. It was concluded that the dry wash had little effect on daily movement of the rodents observed.