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J Exp Biol 215, 21 (2012) 3685-3692
King penguins adjust their diving behaviour with age.
Maryline Le Vaillant 1, Rory P Wilson 2, Akiko Kato 1, Claire Saraux 1, Nicolas Hanuise 1, 3, Onésime Prud'Homme 1, Yvon Le Maho 1, Céline Le Bohec 1, 4, 5, Yan Ropert-Coudert 1
(01/11/2012)

Increasing experience in long-lived species is fundamental to improving breeding success and ultimately individual fitness. Diving efficiency of marine animals is primarily determined by their physiological and mechanical characteristics. This efficiency may be apparent via examination of biomechanical performance (e.g. stroke frequency and amplitude, change in buoyancy or body angle, etc.), which itself may be modulated according to resource availability, particularly as a function of depth. We investigated how foraging and diving abilities vary with age in a long-lived seabird. During two breeding seasons, small accelerometers were deployed on young (5 year old) and older (8/9 year old) brooding king penguins (Aptenodytes patagonicus) at the Crozet Archipelago, Indian Ocean. We used partial dynamic body acceleration (PDBA) to quantify body movement during dive and estimate diving cost. During the initial part of the descent, older birds exerted more effort for a given speed but younger penguins worked harder in relation to performance at greater depths. Younger birds also worked harder per unit speed for virtually the whole of the ascent. We interpret these differences using a model that takes into account the upthrust and drag to which the birds are subjected during the dive. From this, we suggest that older birds inhale more at the surface but that an increase in the drag coefficient is the factor leading to the increased effort to swim at a given speed by the younger birds at greater depths. We propose that this higher drag may be the result of young birds adopting less hydrodynamic postures or less direct trajectories when swimming or even having a plumage in poorer condition.
1 :  Département Ecologie, Physiologie et Ethologie (DEPE-IPHC)
CNRS : UMR7178 – Université de Strasbourg
2 :  Biosciences
Swansea University
3 :  Centre d'études biologiques de Chizé (CEBC)
CNRS : UPR1934
4 :  Centre for Ecological and Evolutionary Synthesis (CEES)
Department of Biology – University of Oslo
5 :  LEA BioSensib
Centre Scientifique de Monaco
Sciences du Vivant/Biodiversité/Evolution

Sciences de l'environnement
acceleration – age – buoyancy – diving – PDBA – swim speed – seabirds

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