Sex differences in Adelie penguin foraging strategies

Consistent sex differences in foraging trip duration, feeding locality and diet of breeding Adelie penguins (Pygoscelis adeliae) were demonstrated at two widely separated locations over several breeding seasons. Differences in foraging behaviour were most pronounced during the guard stage of chick rearing. Female penguins made on average longer foraging trips than males, ranged greater distances more frequently and consumed larger quantities of krill. In contrast, males made shorter journeys to closer foraging grounds during the guard period and fed more-extensively on fish throughout chick rearing. Mean guard stage foraging trip durations over four seasons at Bechervaise Island, Eastern Antarctica and over two seasons at Edmonson Point, Ross Sea ranged between 31 and 73 h for females and 25 and 36 h for males. Ninety-percent of males tracked from Bechervaise Island by satellite during the first 3 weeks post-hatch foraged within 20 km of the colony, while the majority(60%) of females travelled to the edge of the continental shelf (80-120 km from the colony)to feed during this period.