. Dietary change over winter migration in Spheniscus magellanicus yearlings inferred though stable isotopes analysis

SILVA, LAURA; CRESPO ENRIQUE ALBERTO; SILES, L; VALES, DAMIÁN GUSTAVO; GARCÍA NÉSTOR ANÍBAL; SAPORITI, FABIANA; TAVAREZ, M; DE OLIVEIRA, LARISSA ROSA; CARDONA, LUIS

Brest

Conferencia; 8th ISOECOL, International Conference on Applications of Stable Isotope Techniques to Ecological Studies; 2012

researchers and students from universities, governmental institutions and industry

Stable isotope analysis is a powerful tool to infer and compare trophic relationships and diets between different habitat types during animal movements. Feathers have been the most widely used tissue to the track the migration of seabird species with a well known patter of sequential molt. This is not possible, however, with penguins, as they moult all their feathers simultaneously. In order to solve this problem we measured the stable isotope ratios of carbon and nitrogen along the claws of yearlings of Magellanic penguin (Spheniscus magellanicus) to infer the existence of ontogenic dietary changes and gain a further insight into the poorly know winter throphic ecology of young Magellanic penguins. A capture-tag-recapture experiment conducted in a nesting colony in Península Valdes revealed a mean growth rate of 0,11 ± 0,02 mm day -1. These results show that an entire penguin claw represents an average time span of 6 months and hence the claws of yearling penguins collected in Brazil during the winter months would inform about the diet offered by parents while in the nesting colonies (claw tip), the diet consumed during fall off Argentina (claw center) and the diet consumed during winter off southern Brazil (claw base).. The results indicate that there is a significant change in the isotope signatures between the portions of the claw corresponding to the breeding season and the wintering period (MANOVA, p