Rainfall events drive foraging choices by an urban coloniser

Adverse weather reduces the spatial use of an opportunistic gull

Studying the individual or population response of species to variations in weather is gaining impetus due to increased interest in quantifying the effect of global change on biodiversity. Our goal here was to test the role of meteorological conditions (particularly extreme weather) on the activity budget of a generalist seabird species during its breeding season. To this end we used data from GPS-tracked adult yellow-legged gulls (Larus michahellis). Precipitation and wind had a significant impact on spatial use, reducing foraging distances and forcing gulls to spend a longer period within the colony and promoting a change in habitat use. The results suggest that rainfall and wind forced breeding gulls to desist from the area and habitats used under favourable weather, which might affect chicks’ food provisioning. In a future with increasing rainfall and a higher number of extreme bad weather events, investigation should be conducted to establish the extent to which reduction in spatial use may negatively impact reproduction and, hence, demography.