High importance of fish prey in the diet of Yellow-legged Gull Larus michahellis chicks from the southeast Bay of Biscay

The aim of the study was to describe Yellow-legged Gull Larus michahellis chick diet in the southeast Bay of Biscay. Sampling was carried out in three colonies (Ulia, Santa Clara, Guetaria) in Gipuzkoa, northern Iberia, during the breeding seasons of 2007 and 2008. Regurgitates (n = 70) were collected from chicks of c. 20 days old when they were ringed. Overall, 79 prey items were found, and each item was weighed and classified into one of the following prey-groups: marine (fish (Pisces), crab (Brachyura)), refuse tips (pork, beef, rabbit, chicken), terrestrial (earthworms (Lumbricinae), molluscs (Mollusca), insects (Insecta)), others (mainly vegetables or unidentified prey). The proportion of each prey-group did not differ from one year to the next and most prey was of marine origin (59.5%; all fish except for one crab), followed by refuse tips (22.8%), terrestrial (13.9%), and others (3.8%). These findings concur with those at colonies in northwest Iberia, and while local exceptions might occur, Yellow-legged Gull chick diet in northern Iberia is predominantly marine fish.

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