Larger foraging range but similar habitat selection in non-breeding versus breeding sub-Antarctic penguins

For land-breeding marine organisms such as seabirds, knowledge about their habitat use has
mainly been gained through studies of breeding individuals that are constrained to return frequently to their
breeding grounds. In this study we set out to measure whether: a) habitat selection in the non-breeding
period predicts habitat selection in the breeding period, and b) whether breeding individuals concentrated
their activity on the closest suitable habitats. Macaroni Eudyptes chrysolophus and gentoo Pygoscelis papua
penguins, two marine predators with contrasting foraging strategies, were tracked from the Iles Kerguelen
and their habitat selection investigated through Mahalanobis distances factorial analysis. This study
presents the first data about gentoo penguins’ juvenile dispersal. For both species, results showed 6.9 times
larger maximum ranges and up to 12.2 times greater distances travelled during the non-breeding period.
Habitat suitability maps suggested both species made similar environmental selections whatever the period.
Macaroni penguins targeted pelagic areas beyond the shelf break while gentoo penguins always remained
over the shelf. We consider the ecological significance of larger scale movements made outside the
breeding period and suggest that this non-breeding period is of particular interest when attempting to
understand an animal’s habitat selection.