Gentoo penguins have an average length of 80cm and an average weight of 5kg. They have a reddish orange bill, apart from the black culminicorn, and orange feet. White patches above each eye meet across the crown, with white speckling in the adjacent black plumage around the head. Females are slightly smaller than the males, but have similar markings.
Colonies rarely comprise of more than a few hundred breeding pairs, breaking up into smaller subcolonies when numbers exceed this. The preferred nesting sites are low coastal plains, fairly close to a sandy or shingle beach, which is used to gain access to the open ocean. A substantial amount of guano and waste accumulates around the nesting area during the breeding season, and colonies usually move a short distance onto fresh ground each season, retaining the same path to the sea.Gentoo penguins are ground nesting birds, making rudimentary nests from stones, sticks, grass, feathers, or practically any material that they can find suitable for the purpose. Egg-laying is usually completed by late October, with two equally sized eggs of about 130g being laid. Incubation takes about 34 days, with both parents sharing incubation duties, and nest changes occurring every 1 to 3 days. Despite the two eggs being laid 4 days apart from each other, they both hatch within the space of 24 hours.
