The breeding biology and behaviour of the Snares crested penguin

Abstract

Abstract Aspects of the breeding and moulting behaviour of the Snares crested penguin Eudyptes robustus were studied over six seasons. The birds nest only on the Snares Islands (48°S; 166°E) and in the southern summer. The bird is considered worthy of full specific status, despite similarities to the Fiordland crested penguin E. pachyrhynchus. Male E. robustus are larger and heavier than females and the extent of this sexual size dimorphism was examined from breeding pairs and from random samples of adults, yearlings and chicks. The size dimorphism is detectable in yearlings and may begin in the chick stage. There are about 114 and 21 colonies of Snares crested penguins on the Main and Broughton Islands respectively. The average colony in 1969 produced about 44 fledglings. The world population may number between 30 000 and 50 000 birds. Maturity is deferred. The youngest known to have bred is a six-year-old male which reared a chick at least to the creche stage. Two other six-year-olds and one seven-year-...