The Antarctic petrel (Thalassoica antarctica ) is a boldly marked dark brown and white petrel, found in Antarctica, most commonly in the Ross and Weddell Seas. They eat Antarctic krill, fish, and small squid. They feed while swimming but can dive from both the surface and the air.
The adult Antarctic petrel has a brown head, sides, throat, and back. The bill is dark brown and the feet are grey. The underparts are white and their tail and secondaries on the wings are white with brown tips. These are medium-sized relative to other petrels with a wingspan of 100–110 cm (39–43 in), a length of 40–45 cm (16–18 in), and an average weight of 675 g (23.8 oz).
The Antarctic petrel, as its name implies, lives and breeds in the Southern Ocean, and on the Antarctic islands. They nest on snow-free cliffs and rock faces, on the coast or on offshore islands. However, they have been found up to 250km inland. Another common roosting spot is icebergs. Breeding colonies during the October-November breeding period, can be as large as more than 200,000 pairs.
They occasionally migrate to Australia or New Zealand in late winter. Unfortunately, this tends to occur when they're caught in a bad storm.
The petrel's diet is mainly krill, squid and small fish. Food is usually seized when the bird is on the surface but they also plunge-dive to obtain food, diving up to a depth of 1.5 m (4 ft 11 in).
The Antarctic petrel breeding period is during October-November. Each pair lays a single egg, which they incubate for 45-48 days after which there is a 42-47 day nestling period. Both members of the pair incubate the egg, 4% of pairs are female-female.
Eggs have a 70-90% hatching rate. The two main causes of egg loss were predation by South polar skuas, and an egg rolling out of the nest and freezing.
This petrel has an estimated occurrence range of 77,500,000 km2 (29,922,917 sq mi) and between 10 and 20 million adult birds. Due to its huge range and large numbers, it has been classified by the International Union for Conservation of Nature as a species of least concern.
