MEPS 310:247-261 (2006) - doi:10.3354/meps310247
Environmental conditions and life history constraints determine foraging range in breeding Adélie penguins
Judy Clarke1,*, Louise M. Emmerson1, Petr Otahal2
ABSTRACT: Foraging movements of Adélie penguins are constrained both by environmental conditions (e.g. sea ice cover) and life history factors (e.g. regular offspring provisioning). We describe within season changes in foraging range, trip duration and body condition of Adélie penguins nesting at Béchervaise Island, East Antarctica, in the context of these constraints. Penguins were satellite tracked over multiple seasons during the incubation, guard, crèche and pre-moult phases of their annual cycle. They ranged farthest during incubation when sea ice was extensive and shortest during the guard stage when chicks were small and sea ice limited in extent. Prior to their annual moult the birds foraged hundreds of kilometres to the west and east of their breeding sites. A recurrent polynya facilitated access to the sea early in the season when ice cover was extensive. Kernel analyses showed that penguins foraged most intensively close to the colony, along submarine canyons and at the continental shelf break. Increases in foraging range, as the chick rearing period progressed, were consistent with changing energy requirements of adults and chicks and likely intraspecific competition. Whilst provisioning their offspring, penguins adopted a variable combination of time minimising and food maximising foraging behaviour in which choice of foraging rule was determined largely by adult body condition.
KEY WORDS: Satellite tracking · Pygoscelis adeliae · Foraging range · Chick provisioning · Body condition · Kernel analysis · Polynya
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