Paternal behaviour and killing of young in Arctic ground squirrels

Abstract

During the summers of 1977, 1978 and 1979, I investigated killing of infants and young juveniles (for simplicity referred to herein as infanticide) and paternal behaviour in a population of Arctic ground squirrels, Spermophilus parryii, near Haines Junction, Yukon Territory. Males defended territories primarily during the period when young ground squirrels were mot susceptible to being killed. Killing was most likely after removal of males that had been resident during the mating period. Immigrant males, which were unlikely to have sired the young in their new area of residence, tended to kill young, and it appeared that infanticide was a consequence of a male's establishing residence in a new area. An analysis of the time budget of males and females suggested that males acted as lookouts during lactation, when females were spending the most time feeding. I suggest that males behave paternally through defending territories because they increase the likelihood of survival of young that they may have sired; I also discuss the various tactics that both males and females might be expected to adopt given the existence of infanticide in the population.