title: Inter-Annual Variability of Fledgling Sex Ratio in King Penguins.
abstract: As the number of breeding pairs depends on the adult sex ratio in a monogamous species with biparental care, investigating sex-ratio variability in natural populations is essential to understand population dynamics. Using 10 years of data (2000-2009) in a seasonally monogamous seabird, the king penguin (Aptenodytes patagonicus), we investigated the annual sex ratio at fledging, and the potential environmental causes for its variation. Over more than 4000 birds, the annual sex ratio at fledging was highly variable (ranging from 44.4% to 58.3% of males), and on average slightly biased towards males (51.6%). Yearly variation in sex-ratio bias was neither related to density within the colony, nor to global or local oceanographic conditions known to affect both the productivity and accessibility of penguin foraging areas. However, rising sea surface temperature coincided with an increase in fledging sex-ratio variability. Fledging sex ratio was also correlated with difference in body condition between male and female fledglings. When more males were produced in a given year, their body condition was higher (and reciprocally), suggesting that parents might adopt a sex-biased allocation strategy depending on yearly environmental conditions and/or that the effect of environmental 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∶1 equilibrium upon first breeding attempts, as would be expected from Fisher's classic theory of offspring sex-ratio variation.
authors.affiliation: Université de Strasbourg, Institut Pluridisciplinaire Hubert Curien, Laboratoire International Associé LIA-647 BioSensib, Strasbourg, France; CNRS, UMR-7178, LIA-647 BioSensib, Strasbourg, France.
authors.forename: Célia
authors.initials: C
authors.lastname: Bordier
authors.affiliation: Université de Strasbourg, Institut Pluridisciplinaire Hubert Curien, Laboratoire International Associé LIA-647 BioSensib, Strasbourg, France; CNRS, UMR-7178, LIA-647 BioSensib, Strasbourg, France; AgroParisTech ENGREF, Paris, France; IFREMER - UMR 212- Ecosystème Marin Exploité, Sète, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Saraux
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive, Equipe Ecologie Comportementale, UMR 5175 CNRS, Montpellier, France; Université de Strasbourg, Institut Pluridisciplinaire Hubert Curien, Laboratoire International Associé LIA-647 BioSensib, Strasbourg, France; CNRS, UMR-7178, LIA-647 BioSensib, Strasbourg, France.
authors.forename: Vincent A
authors.initials: VA
authors.lastname: Viblanc
authors.affiliation: Université de Strasbourg, Institut Pluridisciplinaire Hubert Curien, Laboratoire International Associé LIA-647 BioSensib, Strasbourg, France; CNRS, UMR-7178, LIA-647 BioSensib, Strasbourg, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Gachot-Neveu
authors.affiliation: Université de Strasbourg, Institut Pluridisciplinaire Hubert Curien, Laboratoire International Associé LIA-647 BioSensib, Strasbourg, France; CNRS, UMR-7178, LIA-647 BioSensib, Strasbourg, France.
authors.forename: Magali
authors.initials: M
authors.lastname: Beaugey
authors.affiliation: Université de Strasbourg, Institut Pluridisciplinaire Hubert Curien, Laboratoire International Associé LIA-647 BioSensib, Strasbourg, France; CNRS, UMR-7178, LIA-647 BioSensib, Strasbourg, France; Centre Scientifique de Monaco, LIA-647 BioSensib, Principality of Monaco.
authors.forename: Yvon
authors.initials: Y
authors.lastname: Le Maho
authors.affiliation: Centre Scientifique de Monaco, LIA-647 BioSensib, Principality of Monaco; Université de Strasbourg, Institut Pluridisciplinaire Hubert Curien, Laboratoire International Associé LIA-647 BioSensib, Strasbourg, France; CNRS, UMR-7178, LIA-647 BioSensib, Strasbourg, France; University of Oslo, Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, Blindern, Norway.
authors.forename: Céline
authors.initials: C
authors.lastname: Le Bohec
mesh_terms: D000818:Animals; D001947:Breeding; D002980:Climate; D005260:Female; D006801:Humans; D008297:Male; D012621:Seasons; D012744:Sex Ratio; D046429:Spheniscidae