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.
We interrogated some aspects of the spatial-social interface for a colonial seabird, the Atlantic puffin (Fratercula arctica). 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 after controlling for the distance between nests. 
The Atlantic puffin is a colonial seabird that has limited movements on land but does travel when out of the nest. We colour-banded 124 individuals, georeferenced their burrows and tracked their associations at the colony using a scan sampling approach during the breeding season. 
We found that the distance between burrows strongly influenced the social network structure of the Atlantic puffin. Individuals formed communities and associated significantly more than expected by chance with neighbours nesting closer, suggesting that the presence/absence of neighbours determined the association patterns. Additionally, we found evidence that distant associations with conspecifics were not all random, suggesting 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 social and spatial environments in unison in studying social network structures and provides new evidence for the influence of these mechanisms on colonial animals.