Fat content, fatty acid composition and estimates of energy metabolism of adèlie penguins (Pygoscelis adeliae) during the early breeding season fast.

TLDR: Adelie penguins breeding at Cape Crozier, Antarctica, arrive in the colony from the sea in October at the beginning of the austral summer and both sexes fast while on the breeding colony for 3–6 weeks before returning to the sea to feed.

Abstract: 1. 1. Adelie penguins (Pygoscelis adeliae) breeding at Cape Crozier, Antarctica, arrive in the colony from the sea in October at the beginning of the austral summer. Both sexes fast while on the breeding colony for 3–6 weeks before returning to the sea to feed. 2. 2. Six individuals collected during the first fast period showed decreased blubber thickness and a linearly corresponding decrease in ether extractable fat with time after arrival in the breeding area. Birds contained about 45 per cent of dry weight as fat upon arrival, and in a typical incubation, males decreased to about 20 per cent after day 27. 3. 3. The decrease in fat represents approximately 56 g of fat used per day by fasting male Adelies for the 27-day period. On the basis of this value, it has been estimated that 490 kcal/bird per day approximates energy demands for these fasting birds during the early part of the breeding season. 4. 4. Fatty acid compositions of total ether extractable lipids, subcutaneous fat and abdominal depot fat did not differ significantly except in a few of the long-chain acids. Depot fat fatty acids of normal breeding birds did not change significantly from arrival on the colony to day 27. 5. 5. Proportions of fatty acids in Adelie penguin depot fat correspond with the proportions of fatty acids in their normal diet of krill (Euphausia superba).