The Erect-crested penguin is a medium to large bird. Female penguins are usually smaller than males. The birds have long, slender bill, colored with brown-orange. The head, upper throat and cheeks of adult erected-crest penguins are dark black. The under parts of the bird are white in color. The upper parts, the body and tail of the penguin are colored with blue-black. They have a wide, yellow colored band, starting near the face over each eye, and composing an erect crest. The plumage on the flippers is white ventrally with a black colored spot at the tip, and blue-black dorsally, fringed with white. Compared to adult penguins, juveniles are colored a bit different, and the crest on their head is shorter than that of adults. The upper parts of the chicks are gray-brown, and the under parts are white.
During the winter, Erect-crested penguins live in sub-Antarctic waters, coming ashore only by the beginning of the breeding season. They usually breed on offshore islands in the south coast of New Zealand, including Antipodes, Bounty, Auckland and Campbell Islands. The nesting areas of these penguins are typically beaches as well as coastal cliffs and rocks. They prefer to nest on bare sites or these with scarce vegetation.
Erect-crested penguins are diurnal birds. They are highly social animals, gathering into large nesting colonies. On their breeding grounds, there is a fierce competition for nesting sites, and they can often be seen fighting with each other to get the best location. Mating pairs are able to identify each other by sight. In addition, during the daytime hours, they use harsh, low-pitched vocalizations, consisting of pulsed phrases and pronounced at a steady rate. Every year, in March-April, breeding adults undergo molt, which lasts for 26-30 days. In the middle of April, the penguins leave the colony, going out to sea and staying there until September. Meanwhile, non-breeding penguins molt earlier, in February-March. The erect-crested penguins are excellent divers and swimmers. They are also capable of traveling long distances.
Erect-crested penguins have monogamous mating system. The birds gather into large breeding colonies. In September, the penguins arrive at their breeding colonies. Usually, males arrive before females, finding the nesting site, which the pair used during the previous breeding season. Then, after 2 weeks, the females arrive. The pre-egg period is characterized by increased activity and even occasional fighting. The female typically lays 2 eggs in October. Egg laying takes about 3-5 days, during which the female does not eat. Both the male and the female incubate the eggs. As a general rule, the first laid egg usually doesn't hatch, so, after 35 days of incubation, a single chick hatches out. After 3 days, the female leaves, while the male stays with the hatchling, guarding the nest for the next 3-4 weeks. However, the mother returns every day to feed the young. At the age of 3 weeks, the hatchling joins a crèche of other chicks, but the parents continue to feed the juvenile. After fledging in January-February, the young penguin leaves, going out to sea.
Although the reasons for reduction of their population are presently unknown, it is considered that the birds are affected by changes in oceanographic productivity throughout their range. These changes decrease breeding success of the birds, making adult penguins swim further in order to get food for their offspring.
The population of the Erect-crested penguin is currently decreasing, estimated to 26,000 breeding pairs on the Bounty Islands and 41,000 pairs on the Antipodes Islands, which makes up total population about 150,000 mature birds. On the IUCN Red List, the species is classified as Endangered.