Other Birds of Antarctica
The resource of Antarctic and sub-Antarctic waters supports vast numbers of a variety of seabirds, which play an important role in the marine ecosystem. Nesting grounds in the region are limited, being confined to the scattered sub-Antarctic islands and ice-free localities during the austral summer on the Antarctic continent and Antarctic Peninsula.
Only a few species of Antarctic seabird are adapted to breed regularly on the Antarctic continent, with Emperor (Aptenodytes forsteri) and Adélie penguins (Pygoscelis adeliae), and Antarctic snow petrels (Pagodroma nivea), being the most abundant species. The ability to survive in such climatic extremes is aided by behavioural adaptions and physiological characteristics such as subdermal fat and layers of down and feathers. Though the avifauna of the sub-Antarctic islands is about triple that of the Antarctic, it is considerably poorer than adjacent temperate regions.
Penguins and albatrosses are perhaps the best known of Antarctic marine birds (see separate pages on penguins and albatrosses), but it is the Procellariidae (petrels, prions, fulmars, and shearwaters) which constitute the majority of species that habitat the region.
Petrels, like albatrosses, feed mostly on fish, squid and crustaceans from the ocean. Some species will also feed on eggs and chicks of other birds, placentas and dead pups from seal pupping grounds, and various other carrion. All procellariids lay a single egg, are generally colonial, and both parents share incubation and chick rearing duties.
Skuas (Catharacta maccormicki) are widespread and prominent in the Antarctic. These birds are notorious for their scavenging behaviour, particularly their acts of piracy in pursuing other seabirds and forcing them to drop their catch. They also prey heavily on the eggs and chicks of penguins and small petrels.
Marine birds of the Southern ocean also include gulls, terns and two species of cormorant. Endemic terrestrial birds of this region are few and include the South Georgia Pipit (Anthus antarcticus) and species of freshwater duck on South Georgia and Kerguelen. Two species of sheathbill, pigeon like shorebirds of scavenging habit, are also restricted to the region. Many other landbirds have been recorded as vagrants, but these invariably succumb to the extreme conditions or predators.
Many of the birds of the Antarctic and sub-Antarctic are susceptible to environmental change. They tend to have low reproduction rates and thereby low potential for population recovery. Impacts from human disturbance, such as long-line fisheries, are a further threat to the populations of certain albatross and petrel species.