Population-specific wintering distributions of adult south polar skuas over three oceans

• Published in: Marine Ecology Progress Series
• Main Authors: Weimerskirch, Henri, Tarroux, A, Chastel, Olivier, Delord, Karine, Cherel, Yves, Descamps, Sébastien
• Other Authors: Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Norvegian Polar Research Institute (NPRI), Norwegian Polar Institute
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: Population-specific strategies; Stable isotopes; Catharacta maccormicki; Geolocators; Migration; [SDE]Environmental Sciences; Antarctic; Indian; Pacific; The Antarctic; Antarc*; South Polar Skuas
• Online Access: https://hal.archives-ouvertes.fr/hal-01288006; https://doi.org/10.3354/meps11465

International audience Migratory routes and the areas used during winter have probably been selected tomaximize fitness by providing favorable environmental conditions outside the breeding season. Inpolar environments, because of the extreme winter weather, most breeding species migrate toencounter better conditions in areas that can differ between and also within species. Using geo -location sensors, we found that south polar skuas Catharacta maccormicki from 2 distant populationsbreeding on the Antarctic continent along the Atlantic and Indian Oceans migrate northwardto winter in tropical Indian Ocean and in temperate North Pacific waters, respectively. Mostindividuals from each population winter in different environmental conditions, with water temperaturesranging from 16 to 29°C. Nevertheless, they have very similar activity patterns, spendingmore than 80% of their time on the water, and their feather δ15N values suggest that they probablyfeed at similar trophic levels during the molt. During overwintering, the overall and constant lowactivity level may be partly imposed by molting constraints, but it also suggests that trophic conditionsare good for skuas. The wintering areas of the species correspond to sectors of high concentrationsof breeding or wintering tropical, Northern, and Southern Hemisphere seabird speciesthat are likely to be kleptoparasitized by skuas. A certain degree of individual variation existswithin each population, which induces a spatial overlap in the wintering grounds of distant breedingpopulations. These results have potential important consequences in terms of fitness, geneticdivergence, and susceptibility to climate change and marine pollution.