Inter-nest distances drive most but not all social associations in a colonial seabird

Antoine Morel , Eric Vander Wal, Pierre-Paul Bitton

Social and spatial environments shape the way individuals associate and thus impact their social network structure. However, nowhere are social and spatial mechanisms more likely to be simultaneously entangled and potentially misinterpreted than in colonial species. The Atlantic puffin is a colonial seabird that nests in an underground burrow. Therefore, they are less limited in their land-based movements than open-nesting seabirds. We colour-banded 124 individuals, georeferenced their burrows and tracked their associations at the colony using a scan sampling approach during the breeding season to understand how the spatial distribution of the burrows constrained their associations. 

We tested how the distance between nests in a colony affected (i) individual probability of association and dyadic weight, and (ii) their community structure. We also tested for the presence of non-random associations across different distances. 

We found that the distance between burrows strongly influenced the social network structure of Atlantic puffins. Individuals associated more often with neighbours and did not seem to favour associations with specific adults attending adjacent nests. However, contrary to expectation, we found that groups of individuals formed communities and evidence that distant associations with conspecifics were not all random. We suggest that individuals may seek each other out, if it provides mutual benefits, or have similar spatial and temporal requirements. Our study demonstrates the importance of considering spatial constraints in studying social network structures and provides new evidence for their impact on colonial animals.