title: Trophic ecology of a resident Yellow-legged Gull (Larus michahellis) population in the Bay of Biscay.
abstract: Stable isotopes analyses (SIAs) are an efficient tool to obtain a general insight into the diet of generalist consumers, such as the Yellow-legged Gull (Larus michahellis). Here we analysed δ(13)C, δ(15)N and δ(34)S values in feathers of chicks and adults, and used Bayesian triple-isotope mixing models to reconstruct the diet of a Yellow-legged Gull population breeding in the southeastern Bay of Biscay. Questions to test were (1) whether adults and chicks rely on different feeding resources during breeding period; (2) whether there is a seasonal foraging effect involving a higher proportion of refuse food in winter compared to summer, and (3) the magnitude of the annual variation in diet. Prey consumption differed between colonies, among years, and also varied slightly between seasons, and this was mainly due to a differential use of prey of marine origin. However, diet did not differ between age classes. These results suggest a relatively monotonous diet with only slight variations from year to year, seasonally and at a local geographic scale.
authors.affiliation: Department of Ornithology, Aranzadi Sciences Society, Zorroagagaina 11, E-20014 Donostia-S. Sebastián, Spain. jarizaga@aranzadi-zientziak.org
authors.forename: Juan
authors.initials: J
authors.lastname: Arizaga
authors.forename: Lluís
authors.initials: L
authors.lastname: Jover
authors.forename: Asier
authors.initials: A
authors.lastname: Aldalur
authors.forename: Juan F
authors.initials: JF
authors.lastname: Cuadrado
authors.forename: Alfredo
authors.initials: A
authors.lastname: Herrero
authors.forename: Carola
authors.initials: C
authors.lastname: Sanpera
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D002247:Carbon Isotopes / Q000378:metabolism; D046091:Charadriiformes / Q000254:growth & development / Q000502:physiology*; D004032:Diet; D004784:Environmental Monitoring; D005241:Feathers / Q000737:chemistry; D005247:Feeding Behavior; D009587:Nitrogen Isotopes / Q000378:metabolism; D009752:Nutritional Status; D012621:Seasons; D013030:Spain; D013460:Sulfur Isotopes / Q000378:metabolism; D013997:Time Factors
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D013460:Sulfur Isotopes