Exploitation of distant Antarctic habitats by juvenile macaroni penguins: conservation implications

Abstract The at-sea ecology of marine migratory species has been unevenly studied across life-cycle stages, which limits our understanding of how distant marine ecosystems may be connected. The macaroni penguin Eudyptes chrysolophus is the largest avian consumer of marine resources in the world, however no at-sea distribution data are available on this species' juvenile birds. In this study we successfully tracked nine juvenile macaroni penguins during their post-fledging dispersal from Kerguelen Is., a key population in the southern Indian Ocean. Fledglings crossed the Antarctic Polar Front to the south and unexpectedly reached the Marginal Ice Zone after two months at sea, travelling up to 2,500 km to the southeast of their colony until transmissions ceased. The fact that abundant predators such as juvenile macaroni penguins target Antarctic sea ice habitats to forage is fundamentally new for the species and has important consequences for the management of Antarctic prey resources. Our study brings new elements that clarify the species' ecology during a critical stage of its life cycle, and expand its known connectivity to adjacent ecosystems; these findings will help refining conservation strategies for the southern Indian Ocean populations.