Differential Costs of Locational and Social Dispersal and Their Consequences for Female Group-Living Primates

Abstract Individuals that disperse may leave familiar conspecifics (social dispersal), a familiar home range (locational dispersal), or both. Social and locational dispersal are not necessarily coincident in group-living animals. Here we differentiate among some potential costs of both social and locational dispersal in group-living mammals, including aggression from strangers and unfamiliarity with new habitats. As an example of the utility of distinguishing between social and locational dispersal, we examine patterns of female transfer in Old and New World anthropoid primates. The results suggest that in Old World primates, female transfer is more likely to be frequent in populations without female aggression between groups. In anthropoid primates, female transfer is more likely to be frequent in populations in which home ranges of groups overlap extensively with those of other groups. Female transfer between groups in Old World, but not New World, primates appears to be more common when females suffer few or no costs of social and locational dispersal. We suggest that when there are few, if any, costs of social and locational dispersal (inferred from moderate to extensive home range overlap and the absence of aggression between groups of females), female transfer in Old World anthropoids will be obligate when groups of females cannot be monopolized by a single male and conditional upon the behavior of individual males when groups of females can be monopolized by a single male. When costs of social and locational dispersal exist (inferred from minimal home range overlap and aggression between groups of females), female transfer will be conditional upon competition with other females in their groups.