Relationships of Diet and Roosting Behavior in the European Starling

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Abstract
Foraging benefits commonly have been proposed to explain the occurrence of communal roosting flocks, yet relationships between roosting and foraging behavior remain largely unresolved. We examined diets of roosting European starlings (Sturnus vulgaris), reasoning that if communal roosting provided foraging benefits, then changes in diet composition should correspond to changes in patterns of roosting behavior. Diets were composed mainly of animal matter (64%) early in the postbreeding roosting season (June-July) when roosting flocks were small and numerous. Later in the season, animal foods were replaced by plant materials when small roosts coalesced into fewer but larger roosting flocks. The change in diet corresponded to changes in the pattern of roosting behavior. One major benefit of roosting may be in providing access to plant foods that can be efficiently exploited during the morning and evening commutes from and to the roost.