The Gentoo Penguin is one of three species in the genus Pygoscelis.
Mitochondrial and nuclear DNA evidence suggests the genus split from
other penguins around 38 million years ago, about 2 million years
after the ancestors of the genus Aptenodytes. In turn, the Adelie
Penguins split off from the other members of the genus around 19 million
years ago, and the Chinstrap and Gentoo finally diverging around 14
million years ago.Males have a maximum weight of about 8.5 kg (19
lb) just before molting, and a minimum weight of about 4.9 kg (10.8
lb) just before mating. For females the maximum weight is 8.2 kg (18
lb) just before moulting, but their weight drops to as little as 4.5
kg (10 lb) when guarding the chicks in the nest. Birds from the north
are on average 700 g (1.5 lb) heavier and 10 cm (4 in) taller than
southern birds Gentoo penguin reaches 75–80 cm. They are the
fastest underwater swimming penguins, reaching speeds of 36 km/h.
Gentoo are adapted to very harsh cold climates.
Gentoos breed on many sub-Antarctic islands. The main colonies are
on the Falkland Islands, South Georgia and Kerguelen Islands; smaller
populations are found on Macquarie Island, Heard Islands, South Shetland
Islands and the Antarctic Peninsula. The total breeding population
is estimated to be over 300,000 pairs.
Nests are usually made from a roughly circular pile of stones and
can be quite large, 20 cm high and 25 cm in diameter. The stones are
jealously guarded and their ownership can be the subject of noisy
disputes between individual penguins. They are also prized by the
females, even to the point that a male penguin can obtain the favors
of a female by offering her a nice stone. Two eggs are laid, both
weighing around 500 g. The parents share incubation, changing duty
daily. The eggs hatch after 34 to 36 days. The chicks remain in the
nests for about 30 days before forming creches. The chicks molt into
sub-adult plumage and go out to sea at about 80 to 100 days.
Gentoos live mainly on crustaceans such as krill, with fish making
up only about 15% of the diet. However, they are opportunistic feeders,
and around the Falklands are known to take roughly equal proportions
of fish, crustaceans and squid.
In the water, sea lions, leopard seals, and orca are all predators
of the Gentoo. On land there are no predators of full grown Gentoos.
Skua can steal their eggs; however, some other seabirds have managed
to snatch chicks.