Seasonal prey switching in non-breeding gentoo penguins related to a wintertime environmental anomaly around South Georgia

• Published in: Polar Biology
• Main Authors: Xavier, J. C., Velez, N., Trathan, N., Cherel, Y., de Broyer, C., Canovas, F., Seco, J., Ratcliffe, N., Tarling, G.
• Other Authors: Marine and Environmental Sciences Centre (MARE UC), Universidade de Coimbra Coimbra, British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Centre of Marine Sciences Faro (CCMAR), University of Algarve Portugal, Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Institut National de la Recherche Agronomique (INRA)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Royal Belgian Institute for Natural Sciences Belgium, Centre Hospitalier Régional Universitaire Montpellier (CHRU Montpellier)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: Pygoscelis papua; Diet; Southern Ocean; Antarctic winter; Abnormal environmental conditions; [SDE]Environmental Sciences; Antarctic; Austral; Bird Island; Antarc*; Antarctic Krill; Euphausia superba; Gentoo penguin; Polar Biology
• Online Access: https://hal.science/hal-01849725; https://doi.org/10.1007/s00300-018-2372-8

International audience Information is needed on how anomalous environmental conditions affect important Antarctic ecological sentinels during the winter. Using a non-invasive method (scats), the diet of non-breeding gentoo penguins Pygoscelis papua at Bird Island, South Georgia, was examined during the winter of 2009 when local environmental conditions were abnormal (e.g. warmer sea surface waters). Scats were collected every 2 weeks from May until October 2009 (N = 168); the diet was dominated by the amphipod Themisto gaudichaudii by frequency of occurrence (77.5% of the samples) and by number (70.5% of the total individuals). By mass, different species of crustaceans (T. gaudichaudii and Antarctic krill Euphausia superba) and fish (Champsocephalus gunnari, Lepidonotothen larseni and Pseudochaenichthys georgianus) were the most important in different periods. Numerically, prey switching occurred at the end of winter, when E. superba became more abundant in the penguins’ diets in late September and early October (austral spring), when sea surface temperatures became colder. T. gaudichaudii is sub-optimal prey for gentoo penguins and its consumption most likely reflects a lack of E. superba in local waters. The consumption of T. gaudichaudii and fish, in place of E. superba, was probably insufficient for the penguins to maintain a body condition suitable for reproduction, contributing to the observed late commencement of breeding (i.e. 2–3 weeks) that year. Our results highlight the sensitivity of gentoo penguin populations to variations in environmental conditions, particularly in terms of how these conditions affect the availability of preferred dietary items and potential follow-on effects in the subsequent breeding season.