title: Foraging strategies of incubating and brooding king penguins Aptenodytes patagonicus.
abstract: For oceanic birds like king penguins, a major constraint is the separation of foraging areas from the breeding colony, largely because swimming increases foraging costs. However, the relationship between foraging strategy and breeding stage has been poorly investigated. Using time-depth recorders, we studied the diving behaviour of two groups of king penguins that were either incubating or brooding chicks at Crozet Islands (Southern Indian Ocean) at the same period of the year. Although birds with chicks had the highest predicted energy demand, they made foraging trips half as long as incubating birds (6 vs. 14 days) and modified their time and depth utilisation. Birds with chicks dived deeper during daylight (mean maximum depth of 280 m vs. 205 m for those incubating). At night, birds with chicks spent twice as much time diving as those incubating, but birds at both stages never dived beyond 30 m. Movements to greater depths by brooding birds are consistent with the vertical distribution of myctophid fish which are the main prey. As chick provisioning limits trip duration, it is suggested that it is more efficient for parents to change their diving patterns rather than to restrict their foraging range.
authors.affiliation: Centre d'Ecologie et Physiologie Energétiques, CNRS, 23 rue Becquerel, F-67087 Strasbourg, France Fax: (33) 3 88 10 69 06; e-mail: charrassin@c-strasbourg.fr, , , , , , FR.
authors.forename: J-B
authors.initials: JB
authors.lastname: Charrassin
authors.affiliation: Centre d'Ecologie et Physiologie Energétiques, CNRS, 23 rue Becquerel, F-67087 Strasbourg, France Fax: (33) 3 88 10 69 06; e-mail: charrassin@c-strasbourg.fr, , , , , , FR.
authors.forename: C A
authors.initials: CA
authors.lastname: Bost
authors.affiliation: Institut für Meereskunde, Düsternbrooker Weg 20, D-24105 Kiel, Germany, , , , , , DE.
authors.forename: K
authors.initials: K
authors.lastname: Pütz
authors.affiliation: Centre d'Ecologie et Physiologie Energétiques, CNRS, 23 rue Becquerel, F-67087 Strasbourg, France Fax: (33) 3 88 10 69 06; e-mail: charrassin@c-strasbourg.fr, , , , , , FR.
authors.forename: J
authors.initials: J
authors.lastname: Lage
authors.affiliation: Centre d'Ecologie et Physiologie Energétiques, CNRS, 23 rue Becquerel, F-67087 Strasbourg, France Fax: (33) 3 88 10 69 06; e-mail: charrassin@c-strasbourg.fr, , , , , , FR.
authors.forename: T
authors.initials: T
authors.lastname: Dahier
authors.affiliation: Office National de la Chasse, 85 bis Avenue de Wagram, 75017 Paris, France, , , , , , FR.
authors.forename: T
authors.initials: T
authors.lastname: Zorn
authors.affiliation: Centre d'Ecologie et Physiologie Energétiques, CNRS, 23 rue Becquerel, F-67087 Strasbourg, France Fax: (33) 3 88 10 69 06; e-mail: charrassin@c-strasbourg.fr, , , , , , FR.
authors.forename: Y
authors.initials: Y
authors.lastname: Le Maho
keywords: Breeding stage; Diving; Foraging strategy; Key wordsAptenodytes patagonicus; Penguin