Marine Biology

, Volume 157, Issue 3, pp 545–553 | Cite as

A three-isotope approach to disentangling the diet of a generalist consumer: the yellow-legged gull in northwest Spain

  • Rocío Moreno
  • Lluís Jover
  • Ignacio Munilla
  • Alberto Velando
  • Carola Sanpera
Original Paper


The widespread omnivory of consumers and the trophic complexity of marine ecosystems make it difficult to infer the feeding ecology of species. The use of stable isotopic analysis plays a crucial role in elucidating trophic interactions. Here we analysed δ15N, δ13C and δ34S in chick feathers, and we used a Bayesian triple-isotope mixing model to reconstruct the diet of a generalist predator, the yellow-legged gull (Larus michahellis) that breeds in the coastal upwelling area off northwest mainland Spain. The mixing model indicated that although chicks from all colonies were fed with a high percentage of fish, there are geographical differences in their diets. While chicks from northern colonies consume higher percentages of earthworms, refuse constitutes a more important source in the diet of chicks from western colonies. The three-isotope mixing model revealed a heterogeneity in foraging habitats that would not have been apparent if only two stable isotopes had been analysed. Moreover, our work highlights the potential of adding δ34S for distinguishing not only between terrestrial and marine prey, but also between different marine species such as fish, crabs and mussels.


Stable Isotope Analysis Prey Type Fractionation Factor Refuse Dump Trachurus Trachurus 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



Thanks are given to the Conselleria de Medio Ambiente (“Xunta de Galicia” autonomous regional government) and to the Parque Nacional de las Illas Atlánticas de Galicia, for the facilities to develop this work. We would especially like to thank C. Pérez and C. Díez (University of Vigo, Spain) for help with the collection of feathers, and M. Mulet, M. Salvande Fraga and S. Baños for help with local prey sampling. We also thank to P. Teixidor, P. Rubio, R. Roca, and E. Aracil of the Serveis Científico-Tècnics for their help in stable isotope analysis. R. Moreno was supported by an FPU grant (Ministerio de Educación y Ciencia, Spain). Funding for this work was provided by project VEM2004-08524 from the Spanish Ministerio de Educación y Ciencia and CGL2008-05448-C02-C01 and CGL2008-05448-C02-C02 from the Spanish Ministerio de Ciencia e Innovación.


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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Rocío Moreno
    • 1
  • Lluís Jover
    • 2
  • Ignacio Munilla
    • 4
  • Alberto Velando
    • 3
  • Carola Sanpera
    • 1
  1. 1.Departament Biologia Animal (Vertebrats), Facultat de BiologiaUniversitat de BarcelonaBarcelonaSpain
  2. 2.Departament Salut Pública, Facultat de MedicinaUniversitat de BarcelonaBarcelonaSpain
  3. 3.Departamento Ecoloxía e Bioloxía Animal, Facultade de CienciasUniversidade de VigoVigoSpain
  4. 4.Departamento de Botánica, Facultade de FarmaciaUniversidade de Santiago de CompostelaSantiago de CompostelaSpain

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