Distances Moved by Stephens' Kangaroo Rat (Dipodomys stephensi Merriam) and Implications for Conservation

Movements by Dipodomys stephensi were assessed by live-trapping and radiotelemetry to evaluate consequences of habitat fragmentation for this endangered species. The median of the maximum distances moved between captures was 29.2 m for the 557 individuals with ≥2 captures. The median distance between first and last monthly home-range centers was 17.6 m for individuals captured in ≥2 months. Males moved longer distances than did females; lactating females were especially sedentary. Dispersal distances were similar for juveniles and adults and for two sites with different geometries of habitat patches. The median distance between first and last home-range center of adults radiotracked for 15–127 days was 9.5 m, indicating stable home ranges. However, radiotracked individuals moved greater maximum distances than most live-trapped individuals apparently moved over a lifetime. Much dispersal, therefore, occurs within an area about which animals have knowledge. This should facilitate habitat selection and decrease the cost of dispersal in terms of fitness. The frequency distribution of maximum dispersal distances underestimated the frequency of moves >400 m. Two processes may have contributed to this bias. First, the frequency of long-distance moves was underestimated because we measured dispersal away from a single grid. Second, our trapping grids were located in homogeneous habitat without dirt roads, which appear to facilitate long-distance movement. Unvegetated corridors show promise for increasing the connectedness of local populations of D. stephensi . Connectedness should be considered in management of endangered species such as D. stephensi , because the expected persistence of metapopulations is sensitive to the extent of dispersal and the fitness of dispersers.