Relations between Unit-Groups of Bonobos at Wamba, Zaire: Encounters and Temporary Fusions

Abstract

Inter-group relations among wild bonobos (Pan paniscus) at Wamba, Zaire, are described. Members of two habituated unit-groups were frequently observed to intermingle, mainly at artificial feeding sites, but also in natural vegetation. During such encounters various affinitive behaviors, such as genito-genital rubbing, copulation, and peering were observed between members of different groups. Affinitive interactions between females of different unit-groups were particularly prominent, and appeared to ease the tension caused by the encounter. Males interacted with members of the other group much less frequently than females. Aggressive interactions between members of different groups were rare. Young nulliparous females were observed to transfer between unit-groups during encounters. These observations suggest that bonobos have a regional society above the unit-group level, which is unique among nonhuman primates for which comparable data are available.