Juvenile Gouldian Finches (Erythrura gouldiae) form sibling sub-groups during social integration

Abstract

The organization of animal groups is both a cause of, and consequence of, patterns of interactions among individuals. The stability of animal social organization reflects how individuals construct and maintain resilient patterns of interactions across changes in group size and membership. In this study we describe patterns of social interactions in captive flocks of Gouldian Finches (Erythrura gouldiae) that were exposed to changing social conditions. A flock of adult Gouldian Finches was exposed to two changing conditions, an introduction condition where juveniles were introduced to the flock, and a fission-fusion condition where the flock was split into two smaller flocks and a new group of juveniles introduced to each. We show that the social organization of captive Gouldian finch flocks is characterized by stable homophilic communities of adult females and juveniles. Females showed higher rates of approaches to other adult females, while juveniles maintined higher rates of approaches towards other juveniles. These findings highlight how the stable interactive decisions made by individuals contribute to higher-order patterns of organization in bird flocks. Furthermore, this study is one of the few to demonstrate self-assortment of juveniles in passerine flocks and suggests that peer and sibling interactions are an unexplored area in avian social development.

One hand washes the other: cooperation and conflict in hygiene and immunity

“…These groups could encourage greater cooperation in disease resistance, particularly in high-risk periods like youth and reproduction. For example, juvenile Gouldian finches (Erythrura gouldiae) form kin subgroups when integrating into a novel flock(Kohn et al 2021). Additionally, reproductive individuals might disperse with their offspring to avoid persecution from conspecifics: for example, red deer (Cervus elaphus) with young often spend the first few months of their offspring's life in isolation(Clutton- Brock et al 1982), resulting in reduced social connectedness(Albery et al 2021), and badgers (Meles meles) often dig satellite setts away from their main social group when they are ready to give birth(Macdonald & Newman 2022).…”