Stable isotopes identify age- and sex-specific dietary partitioning and foraging habitat segregation in southern giant petrels breeding in Antarctica and southern Patagonia |
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Authors: | Andrea Raya Rey Michael Polito Diego Archuby Néstor Coria |
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Institution: | (1) Consejo Nacional de Investigaciones Cient?ficas y T?cnicas, Centro Austral de Investigaciones Cient?ficas, Houssay 200, 9410, Ushuaia, Tierra del Fuego, Argentina;(2) Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 South College Road, Wilmington, NC 28403, USA;(3) Consejo Nacional de Investigaciones Cient?ficas y T?cnicas, Instituto Ant?rtico Argentino, Cerrito 1248, C1010AAZ Buenos Aires, Argentina;(4) Departamento de Ciencias Biol?gicas, Instituto Ant?rtico Argentino, Cerrito 1248, C1010AAZ Buenos Aires, Argentina |
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Abstract: | We examined the isotopic signatures (δ13C, δ15N) of adult body feathers from southern giant petrels Macronectes giganteus collected at two breeding colonies in Antarctica (Potter Peninsula and Cape Geddes) and one in southern Patagonia (Observatorio
Island), as well as in whole blood collected from adults of both sexes at each Antarctic colonies and from chicks at Potter
Peninsula. As body feather moult is a continuous process in giant petrels, feathers provide an integrated annual signal of
an adult’s diets and foraging habitats. In contrast, the stable isotope values of adult and chick blood are reflective of
their diets during the breeding season. We found that sex-specific dietary segregation in adults breeding in Antarctica was
notable during the breeding season (blood samples) but absent when examined across the entire year (feather samples). In addition,
blood stable isotope values differed between chicks and adults, indicating that adults provision their offspring with a relatively
higher amount of penguin and seal prey that what they consume themselves. This finding confirms previous work that suggests
that chicks are preferentially fed with prey of presumably higher nutritional value such as carrion. Finally, based on isotopic
differences between major oceanographic zones in the Southern Ocean, our data indicate population-specific differences in
foraging distribution, with Antarctic populations move seasonally between Antarctic and subantarctic zones, while Patagonian
populations likely forage in subtropical waters and in continental shelf habitats year-round. |
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