SEASONAL-CHANGES IN SPACE USE PATTERNS IN THE SOUTHERN GRASSHOPPER MOUSE, ONYCHOMYS-TORRIDUS-TORRIDUS

Radiotelemetry studies of Onychomys torridus torridus in the Chihuahuan Desert revealed that the home ranges of breeding males were twice as large as those of breeding females. Further, home ranges of females overlapped only slightly, whereas home ranges of males overlapped extensively with those of both females and other males. Radiotelemetry data collected at the same site during the nonbreeding season showed that: home ranges of nonbreeding adult males were significantly smaller than those of breeding males; home ranges of nonbreeding adult females did not differ in size from those of breeding females; home ranges of nonbreeding males and females did not differ significantly in size. Home-range overlap among neighboring females also was greater during the nonbreeding season, and many individuals of both sexes shared day burrows at this time. In total, these patterns support hypotheses that males compete among themselves for reproductive females.