title: Huddling behavior in emperor penguins: Dynamics of huddling.
abstract: Although huddling was shown to be the key by which emperor penguins (Aptenodytes forsteri) save energy and sustain their breeding fast during the Antarctic winter, the intricacies of this social behavior have been poorly studied. We recorded abiotic variables with data loggers glued to the feathers of eight individually marked emperor penguins to investigate their thermoregulatory behavior and to estimate their "huddling time budget" throughout the breeding season (pairing and incubation period). Contrary to the classic view, huddling episodes were discontinuous and of short and variable duration, lasting 1.6+/-1.7 (S.D.) h on average. Despite heterogeneous huddling groups, birds had equal access to the warmth of the huddles. Throughout the breeding season, males huddled for 38+/-18% (S.D.) of their time, which raised the ambient temperature that birds were exposed to above 0 degrees C (at average external temperatures of -17 degrees C). As a consequence of tight huddles, ambient temperatures were above 20 degrees C during 13+/-12% (S.D.) of their huddling time. Ambient temperatures increased up to 37.5 degrees C, close to birds' body temperature. This complex social behavior therefore enables all breeders to get a regular and equal access to an environment which allows them to save energy and successfully incubate their eggs during the Antarctic winter.
authors.affiliation: Institut Pluridisciplinaire Hubert Curien, Département Ecologie, Physiologie et Ethologie, UMR 7178, Centre National de la Recherche Scientifique and Université Louis Pasteur, Strasbourg Cedex 02, France. caroline.gilbert@c-strasbourg.fr
authors.forename: Caroline
authors.initials: C
authors.lastname: Gilbert
authors.forename: Graham
authors.initials: G
authors.lastname: Robertson
authors.forename: Yvon
authors.initials: Y
authors.lastname: Le Maho
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Naito
authors.forename: André
authors.initials: A
authors.lastname: Ancel
mesh_terms: D000818:Animals; D000864:Antarctic Regions; D002940:Circadian Rhythm; D002980:Climate; D005247:Feeding Behavior; D005260:Female; D007206:Individuality; D008027:Light; D008297:Male; D012726:Sexual Behavior, Animal; D012919:Social Behavior; D046429:Spheniscidae / Q000502:physiology*; D013696:Temperature; D014887:Weather