Social Behavior and Social Organization in Richardson's Ground Squirrel (Spermophilus richardsonii) in Saskatchewan

Abstract

Richardson's ground squirrels, Spermophilus richardsonii, are territorial in Saskatchewan. Males defend territories prior to, and during, the mating period only. Female territorial behavior is apparent from 1 week after emergence until hibernation. Female territories are retained from year to year by one individual or are transmitted from a female of one generation to a related female of the next. This behavior may promote a decrease in agonistic encounters in the spring inasmuch as fewer interactions would be needed to re-establish territorial boundaries. Recognition results in a reduction of fighting between relatives and also may be important in the initial learning of territorial boundaries by the young. There was a differential utilization of habitat resulting in adult males being active from mid-March to early June, adult females from early April to mid-July, and some young ground squirrels from mid-May until October. The early disappearance of adults could be one means of limiting exploitation of resources and increasing survival of the young. Peaks of agonistic behavior are correlated with the establishment of territories in the spring and with increases in the home range movements of young residents in midsummer. The peak in cohesive behavior is correlated with the emergence of young and results primarily from play with, and recognition of related individuals. Young males had a greater tendency to disperse than any other age and sex, a tendency which would promote outbreeding in a population where related females maintain the same territory from year to year.