Experimentally assessing the role of foraging encounters on social partner choice in a kin-biased bird society

Kin-based social environments are often characterized by prolonged parent-offspring associations and limited dispersal in at least one sex, leading to groups composed of kin as social partners. These high rates of social interactions among relatives in cooperative societies make it difficult to distinguish whether social partner choice is driven by kinship or by repeated encounters with individuals situated at proximity. Here, we experimentally increased the number of foraging encounters among non-kin at a custom feeder setup in the sociable weaver (Philetairus socius), a colonial, cooperatively breeding bird with a kin-based social structure. Individuals encouraged to forage more frequently with non-relatives subsequently developed stronger foraging associations with non-kin at separate, unrestricted feeders. These findings show that repeated opportunities for interaction can promote non-kin social associations even within a kin-based society, contributing to the understanding of proximate mechanisms that underlie social structure.