Inter-Annual Variability of Fledgling Sex Ratio in King Penguins

• Published in: PLoS ONE
• Main Authors: Bordier, Célia, Saraux, Claire, Viblanc, Vincent A., Gachot-Neveu, Hélène, Beaugey, Magali, Le Maho, Yvon, Le Bohec, Céline
• Other Authors: Département Ecologie, Physiologie et Ethologie (DEPE-IPHC), Institut Pluridisciplinaire Hubert Curien (IPHC), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Ecosystèmes Marins Exploités (UMR EME), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM), AgroParisTech, Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), Université Paul-Valéry - Montpellier 3 (UPVM)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-École Pratique des Hautes Études (EPHE), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Sud )-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Centre Scientifique de Monaco, Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences Oslo, Faculty of Mathematics and Natural Sciences Oslo, University of Oslo (UiO)-University of Oslo (UiO)-Faculty of Mathematics and Natural Sciences Oslo, University of Oslo (UiO)-University of Oslo (UiO)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: [SDE]Environmental Sciences; King Penguins
• Online Access: https://hal.science/hal-01095097; https://hal.science/hal-01095097/document; https://hal.science/hal-01095097/file/journal.pone.0114052.pdf; https://doi.org/10.1371/journal.pone.0114052

International audience As the number of breeding pairs depends on the adult sex ratio in a monogamousspecies with biparental care, investigating sex-ratio variability in natural populationsis essential to understand population dynamics. Using 10 years of data (2000–2009) in a seasonally monogamous seabird, the king penguin (Aptenodytespatagonicus), we investigated the annual sex ratio at fledging, and the potentialenvironmental causes for its variation. Over more than 4000 birds, the annual sexratio at fledging was highly variable (ranging from 44.4% to 58.3% of males), and onaverage slightly biased towards males (51.6%). Yearly variation in sex-ratio biaswas neither related to density within the colony, nor to global or local oceanographicconditions known to affect both the productivity and accessibility of penguinforaging areas. However, rising sea surface temperature coincided with an increasein fledging sex-ratio variability. Fledging sex ratio was also correlated withdifference in body condition between male and female fledglings. When moremales were produced in a given year, their body condition was higher (andreciprocally), suggesting that parents might adopt a sex-biased allocation strategydepending on yearly environmental conditions and/or that the effect ofenvironmental parameters on chick condition and survival may be sex-dependent.The initial bias in sex ratio observed at the juvenile stage tended to return to 1:1equilibrium upon first breeding attempts, as would be expected from Fisher’sclassic theory of offspring sex-ratio variation.