Costs and Benefits of Group Foraging in the Teal (Anas Crecca)

This study examines group foraging in the teal (Anas crecca) in the light of some hypothesized foraging and anti-predator effects of grouping. Results suggest that group foraging in the teal acts as an adaptation to exploit spatially and temporally variable feeding environments. First, in a particular feeding patch, teals responded numerically to the variation in prey abundance. Second, foraging groups attracted teals flying over them. Third, arrivals landed close to the foragers and copied feeding methods used by them. However, the use of marginal feeding sites within the patch increased with group size. This disadvantage and the disturbance and exploitation of prey at and near the water surface may decrease foraging efficiency in large groups. Contrary to the results of several other studies, time-budgeting advantage in terms of increased feeding time and decreased vigilance time seemed not to be an important anti-predator benefit of grouping in the teal.