Opportunists with a home advantage

Preferred food, territories or mating opportunities - reasons for conflicts between neighboring groups are manifold in social living animals. Confrontations with conspecifics of neighboring groups are often hostile and members of the same group defend their territory cooperatively. However, common defense presents also a collective action problem: Not all group members participate in each conflict, but still enjoy the benefits of a joint territory. In order to examine which factors influence participation and outcome of intergroup encounters, behavioral scientists observed Verreaux’s sifakas in Madagascar. They showed that these primates seem to decide whether to join a given encounter opportunistically, based on individual incentives and the actual circumstances.