Summer diet of seabirds feeding in sea-ice-covered waters near Svalbard

Abstract

We describe the summer diets of four seabird species. Kittiwake (Rissa tridactyla), Little Auk (Alle alle), Black Guillemot (Cepphus grylle) and Brunnich's Guillemot (Uria lomvia) collected in sea-ice-covered waters near Svalbard. Birds collected in an area filled with young sea-ice, within the seasonal sea-ice zone, were compared with birds collected from the perennial sea-ice zone dominated by multiyear ice. Pelagic Crustacea and fish dominated the diet of birds feeding in young ice, while sympagic Crustacea and fish were most important in the diet of birds feeding in multiyear ice. Boreogadus saida was the most important fish food item. B. Saida was present in the ice in both areas, while sympagic Crustacea were lacking in the area filled with young ice. Important food items in young ice were B. saida (Black Guillemots and Kittiwakes), Cajanus sp. (Little Auks) and Pandalus borealis (Brunnich's Guillemot). B. saida (Black Guillemots, Kittiwakes, Brunnich's Guillemots), Gammarus wilkitzkii (Brunnich's Guillemot, Black Guillemot) and Apherusa glacialis (Little Auk) were most important in multiyear ice. In general, Black Guillemots and Kittiwakes fed on fish, whereas Brunnich's Guillemots fed on the larger, and Little Auks on the smaller, Crustacea. The importance of sympagic species in the diet of seabirds is thought to be closely related to the age and history of the ice in the feeding area.