Territoriality in adult female Columbian ground squirrels

Abstract

The spatial relationships among adult female Columbian ground squirrels (Spermophilus columbianus) were investigated through intensive behavioral observations at an isolated, high-density colony in southwestern Alberta in 1979 and 1980. Population size at spring emergence more than doubled during the study mainly through an increase in number of yearlings. Each adult female established a small home range and actively defended part of it as a territory. All intruding females were chased out, but exclusive use was not achieved. Territorial behavior increased after breeding, declined during late gestation, peaked during lactation, and decreased again after juveniles emerged. The adaptive significance of female territoriality seems to be related mainly to protection of juveniles.