Optimizing travel time to foraging depths: testing predictions in a deep diver, the king penguin

• Published in: Journal of Zoology
• Main Authors: Hanuise, Nicolas, Bost, Charles-André, Handrich, Yves
• 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), Centre d'études biologiques de Chizé (CEBC), Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: behavioural adjustments; depth anticipation; foraging success; diving angle; stroke frequency; swimming speed; transit time; vertical speed; envir; demo; King Penguins
• Online Access: https://doi.org/10.1111/jzo.12026; https://hal.archives-ouvertes.fr/hal-00794657

International audience Optimal foraging theories predict that air-breathing, diving foragers should maximize time spent at feeding depths, and minimize time spent travelling between surface and depth (transits). The second part of this hypothesis was tested in free-ranging king penguins Aptenodytes patagonicus using measurements of vertical speed, swimming speed, body angle and flipper stroke frequency during transits in relation to an index of foraging success (number of wiggles), during the bottom and the ascent phases of the dive. We found that, except for flipper stroke frequency, all measured variables increased with diving depth and foraging activity. The change in vertical speed was driven mainly by a change in body angle and a slight change in swimming speed. These results suggest a shortening of transit duration in response to increased foraging activity. Whereas the time spent commuting between the surface and foraging depths was reduced when foraging activity was high, vertical speed was only at its maximum over a small part of both ascent and descent phases of the dive. Within the first 10 m of descent, vertical speed increased with maximum dive depth and an index of foraging activity, suggesting that penguins anticipated their diving depth and foraging activity. Our results show that foraging king penguins adjust their diving behaviour in response to both diving depth and foraging activity. Further studies should consider ecological, physiological or mechanical constraints as factors that may limit foraging optimization.