Diet choice and reproductive success of great black-backed gulls (Larus marinus) and impacts on local breeding seabird populations

Veitch, Brian G. (2003) Diet choice and reproductive success of great black-backed gulls (Larus marinus) and impacts on local breeding seabird populations. Masters thesis, Memorial University of Newfoundland.

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Abstract

The relationship between Great Black-backed Gull (Larus marinus) diet selection and reproductive success, measured as chick growth and fledge rates, was undertaken on 2 colonies in the Northwest Atlantic; Gull Island, Newfoundland and the Gannet Islands, Labrador in 2000 and 2001. Habitat and nesting density proved not to be related to diet or reproductive success. Although statistically insignificant, Great Black-backed Gulls that mainly fed their chicks seabirds had in increased growth rates and decreased fledging rates. -- Great Black-backed Gull diet was partially composed of seabird eggs, chicks, and adults. Great Black-backed Gulls had no significant effect on the breeding population of seabirds at the Gannet Islands Ecological Reserve, Labrador. However, at Gull Island, Witless Bay, Newfoundland gulls depredated 2.2% of Kittiwake adults and 22.3% of the eggs/chicks of Black-legged Kittiwakes (Rissa tridactyla), consistent with observations that Kittiwake populations have been declining since the 1990s. Great Black-backed Gull predation seemed to have no significant effect on other seabird populations at Gull Island.

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