Food exploitation: searching for the optimal joining policy.

Commonly invoked foraging advantages of group membership include increased mean food intake rates and/or reduced variance in foraging success. These foraging advantages rely on the occurrence of 'joining': feeding from food discovered or captured by others. Joining occurs in most social species but the assumptions underlying its analysis have been clarified only recently, giving rise to two classes of model: information-sharing and producer-scrounger models. Recent experimental evidence suggests that joining in ground-feeding birds might be best analysed as a producer-scrounger game, with some intriguing consequences for the spatial distribution of foragers and patch exploitation.