Understanding Interindividual Social Networks in Mixed-Species Bird Flocks

AbstractMixed-species flocks (MSFs) are an important form of animal social organization. Most studies examine MSFs at the species level, notwithstanding that social interactions occur between individuals. Empirical studies of multispecies, individual-level MSF social networks have seldom been undertaken. In this study, we use mist netting, color banding, and standardized observations to construct individual-level social networks for MSFs in the Eastern Himalaya. We describe two distinct flocktypes comprising two sets of understory species. Our social network analyses and spatial visualization suggest that the pattern of individual-level co-occurrences differs between these flocktypes and with previously described Neotropical MSFs. One flocktype has a multi-individual territorial network among individuals of its central species, while the other is led by a species with no apparent social structure. Furthermore, the addition of associating species has opposite impacts on the modularity of the two different social networks. Our study provides novel insights into MSFs at the individual level.