Behavioural adjustments during foraging in two diving seabirds: king and macaroni penguins

• Published in: Marine Biology
• Main Authors: Tessier, Eugénie, Bost, Charles-André
• Other Authors: Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: [SDE]Environmental Sciences; Indian; Eudyptes chrysolophus; King Penguins
• Online Access: https://hal.archives-ouvertes.fr/hal-02971087; https://doi.org/10.1007/s00227-020-03711-z

International audience Optimal foraging theory predicts that diving predators should maximise their energy intake while minimizing the costs oftheir foraging activities at depth. This hypothesis was tested in two breath-hold divers that foraged in the pelagic waters offKerguelen Island, southern Indian Ocean. Macaroni penguins (Eudyptes chrysolophus) feed predominately on crustaceansat moderate depths (ca. 50 m), while king penguins (Aptenodytes patagonicus) feed on mesopelagic fish at deep depths(ca. 100–150 m). We instrumented 22 penguins with time-depth recorders during the breeding season of the 2014 southernsummer, just before they went to sea. Birds were recaptured after one to five foraging trips and the dive data were analysedon the level of single dive cycles and entire dive bouts. Both species adjusted their diving behaviour and modulated theirforaging activity in accordance with their experience in their previous dives. Foraging activity during a dive (in terms ofnumber of wiggles per dive) was greater if birds targeted the same depth as the previous dive. The penguins spent less timeat the surface between two prey capture attempt dives than when a prey capture attempt dive was preceded by a non-preycapture attempt dive. Dive bout analyses showed that foraging activity increased with bout duration, while transit time duringdives decreased with bout duration. Our findings are in general agreement with predictions based on optimal foragingmodels. The results suggest that penguins anticipated the depth of their next dive based on their encounter of a prey patch inthe previous dive and optimized their chances of feeding success by spending minimal time at the surface and in transit tothe patch depth. Once penguins detected a prey patch, these behavioural adjustments allowed them to rapidly return to thatpatch, increasing their chances of feeding again before the prey disperses.