CONICET | Buscador de Institutos y Recursos Humanos

Rationale: Food provisioning is considered one of the main traits affectingoffspring fitness. Differences in food provisioning between sexes, particularlyin dimorphic species, could affect the amount and type of food provided, due todifferences in the amount of food carried to the nest as a result of differentialresources exploitation. Quantitative evidence for sexual differences in foodprovisioning by parents in penguins is scarce. The Magellanic penguin is moderatelysexually dimorphic and breeds along a broad latitudinal range, with birds northand south of this range being essentially dietary specialists while those atintermediate latitudes consuming a more diverse diet.Methods: We used stable isotopeanalysis of carbon and nitrogen to examine if there was a differential parentalcontribution to chicks in ten Magellanic penguin colonies throughout itslatitudinal breeding distribution. We used the heuristic Euclidean isotopicdistance (ED) and individual isotope distances between the chicks and their parentsas a proxy for diet similarity (the smaller the distance, the more similar thediet). Results: The analysis showed that chicks tended to have a more similar dietto that of their male parent and that this pattern was more evident at colonies and in seasons where penguins had amore diverse diet, which could be explained by differences in diet betweenparents. Distance in δ15N values, but not in δ13C values,differed between both sexes and their chicks in all the pairs sampled,suggesting that δ15N values drive the differences found in EDbetween chicks and their parents.Conclusion:We have developed an approach that provides thefirst assessment of the extent of differential food provisioning between maleand female Magellanic penguins. Results suggest chickshave a diet more similar to that of their male parent, likely related to thehigher trophic level of male penguin prey.

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