Social network differences across the breeding season in a burrowing seabird with assumed similar sex-roles

Antoine Morel , Pierre-Paul Bitton

Changes in behaviours that follow seasonal cycles can affect social interactions, which in turn influence social network structures. Because such behaviours are often sex-related, their effect on social associations can impact males and females differently. While the effects of sex-related behaviours on the social network structure of species with distinct parental roles have been studied, their effects on species with seemingly similar parental tasks remain uncertain. We tested how social network trait values changed over the breeding season and whether they differ between males and females in Atlantic puffins (Fratercula arctica), for which parental roles are assumed to be very similar but perhaps non-identical. We studied associations between 120 colour-banded, sexed individuals and conducted scan sampling during the breeding season. We tested how social networks, built using a time-aggregated network method, changed over the breeding season. We found significant social network changes during the breeding season, with many of the traits changing during the peak hatching period. Social network traits followed similar trends for males and females during incubation but showed some evidence of divergence during the brood-rearing period. Our study demonstrates that Atlantic puffins have higher sociality during the chick-rearing period than during incubation and that males generally have greater network trait value rates of change, suggesting that they are more affected by shifts in parental behaviours than females. Because sex-related time budgets in the Atlantic puffin are unclear, we highlight the importance of having an accurate baseline of sex-related roles to interpret social structures.