The erect-crested penguin is an extremely social bird that breeds in large, raucous colonies of several thousand pairs, usually alongside rockhopper penguins (Eudyptes chrysocome) (4) (6). This species uses a number of displays and vocalisations, utilised particularly in the courtship and breeding season and in aggressive territorial behaviour during mate matching or when defending nesting sites (3) (6). Courtship displays include an enthusiastic greeting with an open bill, vertical head swinging, trumpeting, quivering, bowing and preening (3). Aggressive displays include use of the crests, growling and barking, while direct fighting involves twisting of locked bills or biting of the enemy on the neck while beating them with the flipper (3) (6).
Males usually return to the breeding site in September, and compete fiercely for prime nesting sites (6) (7). The females join the males two weeks later and work together to construct nests made of mud, stones and grass (3). Two eggs are laid in early October, although the first egg, which is noticeably smaller than the second, is usually lost (4) (6). The second egg is up to twice as large as the first, and is the only one seriously incubated (5). The male and female take turns incubating the egg for about 35 days (3) (6). After hatching, the chicks are fed regurgitated food by the female until they fledge in February. For three to four weeks the male stands guard without food while the female forages and returns daily to feed the chick (3) (6). Adults return to the sea for the (austral) winter after moulting in March (3) (7).
Little is known about the feeding habits of the erect-crested penguin, but the main sources of food are thought to be krill and squid, occasionally supplemented by small fish (2) (6).