QUANTIFICATION OF COMPETITION AMONG COEXISTING HETEROMYIDS IN THE SOUTHWEST

Three trapping grids, 225 m on a side were established in the desert of southern New Mexico. On grid 1 all Dipodomys (Heteromyidae, Rodentia) were removed; on grid 2 all Perognathus (Heteromyidae, Rodentia) were removed; and on grid 3 no rodents were removed. All grids were censused at two-week intervals for six weeks. When the larger Dipodomys (40g) were removed, the Perognathus (15g) population increased 2.56-fold (from 27 to 69 individuals) in two weeks. Removal of Perognathus had no effect on numbers of Dipodomys. Our data allow us to estimate the magnitude of the competition between Dipodomys and Perognathus