Gull predation on eider ducklings Somateria mollissima: Effects of human disturbance

Abstract Gull predation on eider ducklings Somateria mollissima in an archipelago on the Swedish west coast is described. Both gull encounter rate and gull predation rate were 200–300 times higher on creches disturbed by boats than on undisturbed creches. Encounter rates increased with the proximity of the creche to breeding sites of gulls and to passing boats. Repeated disturbances further raised gull encounter rates. Near islands with nesting gulls, intense boating activity may severely affect fledgeling production among ducks. Our results suggest that boating should be restricted in important duckling rearing areas.