Inter-Research > MEPS > v377 > p289-297  
MEPS
Marine Ecology Progress Series

via Mailchimp

MEPS 377:289-297 (2009)  -  DOI: https://doi.org/10.3354/meps07792

Feeding ecology of yellow-legged gulls Larus michahellis in the western Mediterranean: a comparative assessment using conventional and isotopic methods

Raül Ramos1,*, Francisco Ramírez1, Carolina Sanpera1, Lluís Jover2, Xavier Ruiz1,†

1Departament de Biologia Animal (Vertebrats), Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 645,
08028 Barcelona, Spain
2Departament de Salut Pública, Facultat de Medicina Universitat de Barcelona C/Casanoves 143, 08036 Barcelona, Spain
*Email:
Deceased 27 April 2008

ABSTRACT: Accurate determination of feeding habits using only conventional dietary analysis is usually difficult, due to both biases caused by prey digestibility differences and to the discrete aspect of the sampling. However, combining conventional methods with stable isotope analysis provides an integrated view of the assimilated diet. Here, we measured stable isotope ratios of carbon (δ13C), nitrogen (δ15N) and sulphur (δ34S) in feathers of yellow-legged gull Larus michahellis nestlings from 4 colonies along the western Mediterranean coast, where the gulls consume different proportions of marine, terrestrial and garbage resources. We collected and analysed chicks’ regurgitates in each colony, thereby determining the isotopic signatures in a significant sample of prey. By applying a mixing model to our isotopic values, we compared the information provided by the 2 methodologies. According to direct prey sampling and the particular conditions of the breeding areas, populations with more enriched δ34S values consumed a diet richer in marine prey, with lower δ15N signatures indicating garbage consumption. The main pattern resulting from the mixing model agreed with direct diet sampling. However, estimated proportions for small-sized prey were controversial, which indicates that small, soft prey items might be underestimated by regurgitate analysis. We conclude that stable isotope signatures and the use of mixing models are useful tools for the rapid assessment of feeding ecology in certain populations. Solving analytical biases should be considered in future feeding studies, thereby saving time and minimising bird disturbance by using an isotopic methodology.


KEY WORDS: Carbon-13 · Mixing models · Nitrogen-15 · Regurgitate · Sulphur-34


Full text in pdf format 
Cite this article as: Ramos R, Ramírez F, Sanpera C, Jover L, Ruiz X (2009) Feeding ecology of yellow-legged gulls Larus michahellis in the western Mediterranean: a comparative assessment using conventional and isotopic methods. Mar Ecol Prog Ser 377:289-297. https://doi.org/10.3354/meps07792

Export citation
Mail this link - Contents Mailing Lists - RSS
Facebook - - linkedIn