The Gentoo is the most colorful species among brush-tailed penguins. On the top of its head, the animal has a white thin stripe, connecting with a wide stripe (which is the widest at the eyes) and forming a triangle. The Gentoo penguin has orange-pink feet, bright orange beak, black back and white under parts. The undersides of their flippers are colored in pink. The Gentoo penguin is the only orange-billed species, having the white stripe above their eyes. The penguins have white patches, located either on the top or on the sides of their head. The plumage of newborn hatchlings is silvery-gray. During the first week of their life, their undersides, from the chin down, are colored in white. Young penguins lack these white eye stripes, found in adults. Unlike adults, they are colored somewhat duller: the overall plumage is grey instead of black and the under parts of the flippers are dull pink in color.
The Gentoo penguins are typically found along the coastlines of the Antarctic Peninsula, sub-Antarctic islands and the Falkland Islands in the southern part of the Atlantic Ocean.
The Gentoo penguins are diurnal and social birds, breeding in colonies and remaining together for the rest of the year. They typically live and breed in same areas. These penguins are very shy and do not tend to defend their territories. When encountering a predator, they will simply retreat. However, they become extremely territorial, when it comes to their nests. Every year, these birds undergo molting, which usually takes place right after fledge and departure of the chicks, lasting 25 days. During the molt, they don’t go to forage at the sea. They fast, losing around 200 grams every day. For this reason, before molting, during January, adult individuals travel to the sea to forage, staying there for about 55 days.
Generally, these birds are seasonally monogamous, though some pairs may remain together throughout the life. They congregate into large breeding colonies of up to 2.000 pairs at a breeding site. As the breeding season begins, the pair constructs a nest. The penguins usually build their nests at a distance of about 1 meter from each another. The female lays 2 eggs from June to the end of November. Both the male and the female participate in the incubation process, taking turns. Incubation lasts about 34-36 days, after which the chicks hatch out, staying in the nest for the following 30 days, until they form creches. At about 80-100 days old, the young undergo their first molt, gaining the sub-adult plumage, after which they go out to the sea. Typically, they first breed at 3-4 years of age, though they can occasionally breed earlier - at 2 years old.
Primary concerns to this species include pollution and association with fisheries. On the other hand, human disturbance in the form of scientific studies is among other threats. Thus, penguin colonies on Kerguelen Island and Possession Island have been threatened by scientific bases around the area.
The overall population of the Gentoo penguin is up to 774,000 mature individuals. On the IUCN Red List, the species is classified as Least Concern (LC) with stable population.