Fat King Penguins Are Less Steady on Their Feet

• Published in: PLOS ONE
• Main Authors: Willener, Astrid S. T., Handrich, Yves, Halsey, Lewis G., Strike, Siobhán
• Other Authors: Département Ecologie, Physiologie et Ethologie (DEPE-IPHC), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Department of Life Sciences, University of Roehampton, United Kingdom
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: socio; lang; King Penguins
• Online Access: https://doi.org/10.1371/journal.pone.0147784; https://hal.archives-ouvertes.fr/hal-01356715

International audience Returning to the shore after a feeding sojourn at sea, king penguins often undertake a relativelylong terrestrial journey to the breeding colony carrying a heavy, mostly frontal, accumulationof fat along with food in the stomach for chick-provisioning. There they mustsurvive a fasting period of up to a month in duration, during which their complete reliance onendogenous energy stores results in a dramatic loss in body mass. Our aim was to determineif the king penguin’s walking gait changes with variations in body mass.We investigatedthis by walking king penguins on a treadmill while instrumented with an accelerationdata logger. The stride frequency, dynamic body acceleration (DBA) and posture of fat (prefasting;13.2 kg) and slim (post fasting; 11 kg) king penguins were assessed while theywalked at the same speed (1.4km/h) on a treadmill. Paired statistical tests indicated no evidencefor a difference in dynamic body acceleration or stride frequency between the twobody masses however there was substantially less variability in both leaning angle and theleaning amplitude of the body when the birds were slimmer. Furthermore, there was someevidence that the slimmer birds exhibited a decrease in waddling amplitude. We suggestthe increase in variability of both leaning angle and amplitude, as well as a possibly greatervariability in the waddling amplitude, is likely to result from the frontal fat accumulation whenthe birds are heavier, which may move the centre of mass anteriorly, resulting in a less stableupright posture. This study is the first to use accelerometry to better understand the gaitof a species within a specific ecological context: the considerable body mass change exhibitedby king penguins.