Changes in the foraging range of Adélie penguins as the breeding season progresses

1. This paper describes temporal changes in foraging range throughout the breeding season of Adélie penguins nesting at Béchervaise Island on the Mawson coast of Eastern Antarctica. A decade’s worth of satellite tracking data was loaded into geographical information systems (GIS) software to produce maps of where the penguins travel to feed during each of the incubation, guard, crèche and pre-moult stages of the breeding cycle.
2. Penguins ranged furthest north during incubation and made their shortest trips during the guard stage of chick rearing. An annually recurrent polyna was consistently used as access to the sea during incubation.
3. Kernel analyses showed that penguins foraged most intensively at the continental shelf break and over submarine canyons, particularly whilst feeding chicks. Birds foraging prior to their annual moult travelled hundreds of kilometres to both the west and east of their breeding sites.
4. Foraging ranges at the different stages of the breeding season are consistent with the changing requirements of adults and chicks. However, increases in range as the chick rearing period progresses are also consistent with prey depletion and intraspecific competition.
5. Projection of the foraging ranges demonstrated for the Mawson coast onto other Adélie penguin colonies in the Prydz Bay region indicates varying degrees of overlap depending on the stage of the breeding season and the distance between populations. Overlap in foraging ranges between neighbouring colonies is least likely when chicks are small due to shorter foraging trips at this time.