Kinship, reproductive strategies and social dynamics of yellow-bellied marmots

Abstract

Social behavior of yellow-bellied marmots was observed for three years in colonies where kinship was known and for one year in a high elevation colony where harems were contiguous. Social dynamics of yellow-bellied marmots is dependent on kinship, group composition, and age-sex classes. This pattern is a consequence of the reproductive strategies of males and females. Females behave cohesively toward sisters or daughters, but not with sons and agonistically toward other females. Males generally behave amicably toward females and agonistically toward males, including their sons. Thus, reproductive strategies limit nepotism. This behavior is consistent with a population process in which sons typically disperse as yearlings. At least some of the variation in the expected patterns of social behaviors is attributable to individual differences. Because male and female reproductive strategies differ, a marmot population consists of two social subsystems. The female unit is the closely-related kin group which may also be a burrow group. The male unit is a harem which usually consists of two or more competing female kin groups.