Studies on the Adelie penguin at cape Royds 1964–65 and 1965–66

Abstract

Summary The adult population of the colony, egg sizes, incubation watches, and egg and chick mortality are considered for the 1964–65 and 1965–66 breeding seasons. In 1964–65 1,051 breeding pairs were recorded and 1,467 chicks survived to leave the colony: this represents 67.5% of eggs laid. In 1965–66 1,186 breeding pairs successfully reared 1,390 chicks: 57.0% of eggs laid. Egg and chick mortality over four breeding seasons is considered, with special reference to ice conditions in McMurdo Sound. Dimensions of 349 eggs are given, including those for clutches produced by 33 known females in successive seasons. Breeding success of known pairs of birds is discussed. Birds breeding for the first time appear to lay a single, small egg and to be unsuccessful; experienced breeders which change their mate are usually unsuccessful. Observations are made on chick plumage and panting. A prone sleeping posture in which the bill is directed towards the axilla is described and illustrated. Some observations on the South Polar Skua are recorded.