Mate choice and reproductive success of pikas

Abstract

Factors affecting mate choice and female reproductive success were studied in a population of pikas, Ochotona princeps, in northeastern Oregon. Features of the den habitat (number of entrances to the den, size of the surrounding talus, distance to vegetation, amount of grass and forb present) and the mate or potential mate (weight and age) were analysed with respect to their effects on offspring production and survival, maternal survival and female mate choice. Female pikas chose mates primarily on the basis of the type of den available and the distance from the den to vegetation. These features were the primary determinants of the number of young weaned, but had no significant effects on maternal survival. Paternal weight was an important influence on offspring production, but its effect on female fitness was tempered by a negative effect on female survival. Characteristics important to female choice had no significant influence on the survival of young between weaning and natal dispersal and so cannot be considered to be male ‘handicaps’. Male pikas tended to be philopatric so that sons of males with territories that were attractive to females tended to inherit the attractive territories of their fathers. Female choice among pikas is thus best explained by Darwin's and Fisher's theories of intersexual selection.