DIFFERENTIAL COSTS OF LOCATIONAL AND SOCIAL DISPERSAL AND THEIR CONSEQUENCES FOR FEMALE GROUP-LIVING PRIMATES

Individuals that disperse may leave familiar conspecifics (social disp ersal), a familiar home range (locational dispersal), or both. Social and locational dispersal are not necessarily coincident in group-livin g animals. Here we differentiate among some potential costs of both so cial and locational dispersal in group-living mammals, including aggre ssion from strangers and unfamiliarity with new habitats. As an exampl e of the utility of distinguishing between social and locational dispe rsal, we examine patterns of female transfer in Old and New World anth ropoid primates. The results suggest that in Old World primates, femal e 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 gro ups overlap extensively with those of other groups. Female transfer be tween groups in Old World, but not New World, primates appears to be m ore common when females suffer few or no costs of social and locationa l dispersal. We suggest that when there are few, if any, costs of soci al 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 group s of females cannot be monopolized by a single male and conditional up on the behavior of individual males when groups of females can be mono polized by a single male. When costs of social and locational dispersa l exist (inferred from minimal home range overlap and aggression betwe en groups of females), female transfer will be conditional upon compet ition with other females in their groups.