Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)




Professor Martin Daly


Using radiotelemetry, the spatiotemporal surface activity patterns of the Merriam kangaroo rat (pipodomys merriami) were studied in relation to several physiological and ecological factors. It was found that males were more active than females during the breeding season but not otherwise. Females' surface activity varied in relation to reproductive condition with estrous females most active, pregnant and lactating females intermediate, and anestrous females least active. D. merriami home range sizes were sexually monomorphic in all seasons and ranged in size from 0.03 to 1.16 ha. The majority of activity, however, was restricted to an area of about 0.03 ha. Animals exhibited substantial range overlap with females overlapping males more than other females. No difference was apparent for males. Ranges remained relatively stable in location with only a few animals making substantial shifts. Day burrows, of which animals used several, were regularly distributed so that nearest-neighbors tended to be at maximal distances. As with spatial overlap, females' nearest-neighbors tended to be males.

These findings contribute to the natural history of D. merriami and to the study of small mammal social systems. These findings also suggest that this species may have a more complex social structure than heretofore thought.

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