INIBIOMA   20415
INSTITUTO DE INVESTIGACIONES EN BIODIVERSIDAD Y MEDIOAMBIENTE
Unidad Ejecutora - UE
artículos
Título:
Skuas (Stercorarius spp.) moult body feathers during both the breeding and inter-breeding periods: implications for stable isotope investigations in seabirds
Autor/es:
GRAÑA GRILLI, M.; CHEREL, YVES
Revista:
IBIS
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Lugar: Londres; Año: 2017 p. 266 - 271
ISSN:
0019-1019
Resumen:
Seabirds are mostly believed to moult during the inter-breeding period and the isotopic values of their feathers are related to their diet during such period. We observed Brown Skuas (Stercorarius antarcticus lonnbergi) and South Polar Skuas (S. maccormicki) moulting on the breeding site at King George Island, Antarctica. This raises a doubt about the reliability of the conclusions drawn up about the feeding localities of birds during the inter-breeding period by means of the determination of the stable isotope values of feathers. We analyzed δ13C and δ15N values of growing and fully grown body feathers collected from the same individuals. For both species, δ13C values of growing feathers indicated feeding areas in the Antarctic zone (breeding grounds), while most fully grown feathers could be assigned to northern latitudes (non-breeding grounds). However, a few fully grown body feathers of Brown Skuas showed isotopic values indicating moulting in the Antarctic zone. Since the time-window (growth period) of those feathers is unknown, they cannot be used with confidence to depict the foraging behaviour of the birds during the non-breeding period. Our results aware about the possibility of drawing up misleading conclusions about the origin of the diet when the moulting pattern of the species is unknown, and show that if the state of development of feathers can be determined the occurrence of moult on the breeding grounds allows the determination of the diet of the same bird during two different periods of its annual cycle through one single feather sampling event.