Spatial environment drives land-based social associations in a central-place foraging seabird

Antoine Morel , Eric Vander Wal, Pierre-Paul Bitton

1. 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 central-place foragers.
2. We interrogated the spatial-social interface for a central-place forager in their colony. To do so we tested how the distance between individuals in a colony affected (i) their probability of association, (ii) their community structure, and (iii) and dyadic weight.
3. We used the Atlantic puffin (Fratercula arctica), a central-place forager that has limited movements on land, to determine the contribution of the social and spatial environments to the social network structure. We colour-banded 124 individuals, geo-localised their burrows and tracked their associations at the colony using focal observations during the breeding season.
4. We found that the spatial environment strongly influenced the social network structure of the Atlantic puffin. Individuals formed communities and associated significantly more than expected by chance with their close nesting neighbours, 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.
5. 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 central-place foragers.