The Humboldt penguin is a medium-sized penguin with black-and-white plumage and black head. The base of the bill is fleshy and pink in color. The penguin has white colored patches, stretching from behind each eye down to the black ear coverts and chin, and meeting on the throat. The upper parts are blackish-grey and the under parts are whitish in color. They have a black colored stripe on their breasts, stretching from their flanks to the thigh. Young penguins are identified by lacking this stripe and having dark heads.
Humboldt penguins are highly social and communicative birds, gathering in large colonies, providing them protection from predators. They do not migrate due to warm temperatures throughout the year. These penguins are excellent swimmers. They are diurnal animals. These diurnal penguins see well both underwater and on land. Penguins, not rearing chicks, are able to be away from their colonies and can pass long distances, looking for new foraging areas. However, those, rearing chicks, generally tend to stay in the same area, foraging in shallow water.
The Humboldt penguins have monogamous mating system. Breeding season lasts from March to December, with highest breeding activity in April as well as August-September. Before mating, the animals undergo molting period of about 2 weeks, during which they do not go out to sea and have to starve. By the end of the molt, they finally venture into sea to forage, and then come back to their breeding grounds, where they mate. Usually, 1-2 eggs are laid and incubated for about 40 days. Both the male and female incubate the eggs alternately. When the chicks hatch out, both parents care for them, until the young reach the age of 70-90 days, when they gain their adult plumage. By that time, the young are fully independent and go to sea. Sexual maturity is reached at 3 years old.
The Humboldt penguins are frequently tangled in fishing nets and killed by explosives, used by fishermen. They are threatened because of mining operations, conducted in the area of their range. The animals are captured for illegal pet trade, food as well as for use as fish bait. Human disturbance is among other serious threats to this species' population: in northern part of Chile, an important breeding site of Humboldt penguins is presently under danger due to construction of 2 coal-fired power stations in the area.
The total number of the Humboldt penguin's population varies from 44,239 to 53,462 birds, including 32,000 mature individuals. On the IUCN Red List, the species is classified as Vulnerable (VU).