Exploration during early life: distribution, habitat and orientation preferences in juvenile king penguins

International audienceBackground: The early life of marine apex predators is poorly known, particularly for diving species. The orientationand foraging skills are presumably less developed in juveniles than in adults, especially during their first year at seawhen juveniles might disperse further than adults.Methods: Over two years of monitoring, we tracked the movements of 17 juvenile king penguins (Aptenodytespatagonicus, ~ 1 year old) using satellite relay tags from Crozet Archipelago (Southern Indian Ocean), starting whenbirds left their natal colony for the first time. For comparison we also tagged 6 non-breeding adults, which at thatstage, similar to juveniles, are unhampered by reproductive constraints and might roam further than breeders. Weused a combination of cluster analysis and habitat modelling to investigate and compare the movement patternsand habitat use of experienced (non-breeding adults) and non-experienced (juveniles) individuals.Results: While juvenile penguins and non-breeding adults followed similar routes, the movements by adults startedlater in the season and ranged over a considerably smaller area than juveniles. Net squared displacement analysisrevealed that both groups did not move to a specific wintering area. Changes in direction of juveniles in respect totheir departure island were similar and synchronous for both years. Habitat models revealed that foragingbehaviour was affected by environmental variables such as wind or current speeds, sea surface temperature, oroceanic productivity, for both stages. Analysis of tracks revealed that birds moved predominately perpendicular oragainst the main direction of the Antarctic Circumpolar Current and the prevailing wind during austral summer(juveniles only) and autumn (juveniles and non-breeding adults). However, both juveniles and adults were morelikely to move against the prevailing winds if productivity increased along their trajectories.Conclusions: The exceptional duration of our tracking study provided unprecedented insights into the distribution,habitat preferences and orientation of two poorly known life history stages of an expert avian diver. Our studysuggests that juveniles might use both innate and learnt skills to reach profitable foraging areas during their firstyear at sea, which is critical in long-lived species