Local-scale variability in the diet of Black-legged Kittiwakes Rissa tridactyla

• Main Authors: Lewis, Sue, Bull, J., Wanless, S., Elston, D.A., Daunt, F., Harris, M.P.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Netherlands Ornithologists' Union 2004
• Subjects: Rissa tridactyla; Ammodytes marinus; sandeels; foraging ranges; feeding overlap; clupeids; hinterland; Pacific; Black-legged Kittiwake; North Atlantic; rissa tridactyla
• Online Access: http://researchrepository.napier.ac.uk/Output/2810368

The Black-legged Kittiwake Rissa tridactyla is a small gull that is widely distributed in the North Atlantic and Pacific. During the breeding season it feeds mainly on fish and, in the North Sea, the Lesser Sandeel Ammodytes marinus typically forms the main species in the diet. We compared the diet and breeding performance of Kittiwakes at four colonies in east Britain with potentially overlapping foraging ranges where both Lesser Sandeels and alternative prey (clupeids: Sprat Sprattus sprattus and Herring Clupea harengus) were potentially available. During the four years of the study Kittiwakes at all four colonies showed similar within-season shifts in the age class of sandeel taken with older (1+ group) fish being replaced by young of the year (0 group). However, in every year the predominant prey differed between the two marine colonies, where birds fed mainly on sandeels, and the two estuarine colonies, where clupeids were the most important prey. We suggest that these dietary differences reflect differences in foraging areas such that Kittiwakes from marine colonies feed offshore in areas with a sandy seabed, habitat favoured by sandeels, and birds from estuarine colonies feed closer inshore in areas with a more rocky seabed, habitat favoured by clupeids. Breeding success of Kittiwakes at the four colonies followed a similar trend over the first three years but the marked increase recorded at the marine colonies in 2000 was not apparent at the estuarine colonies.