Results for the GAM with daily foraging mass gain as dependent variable.

Breeding season (2009/10 or 2010/11) and chick rearing stage (guard or crèche) were included as fixed factors, wind speed (in m/s) and wind direction (in degree, circularity was accounted for by a circular smoother) were included as continuous variables. In addition, we included the interaction between wind speed and wind direction (again accounting for the circularity with a smoother). n = 111 days, the model explained 15.8% of the deviance. Significant results are marked in bold.