Petrel (Southern giant petrel) Macronectes giganteus
Species: M. giganteus
Binomial name: Macronectes giganteus
Common name: Southern giant petrel, Antarctic giant petrel, Nelly, Stinker, pangurunguru, Giant fulmar, Glutton, Stinkpot, Sea vulture.
Macronectes giganteus (Southern giant petrel) is a large seabird of the southern oceans. Its distribution overlaps broadly with the similar northern giant petrel, though it overall is centered slightly further south. Adults of the two species can be separated by the colour of their bill-tip: greenish in the southern and reddish in the northern.
The southern giant petrel is the largest of all the petrel species and measures 86 to 99 cm, with a wingspan of 185 to 205 cm and a weight of 3.8 - 5.0 kg.
This species as two colour forms: white morph (c.10%) and dark morph (c.90%). White morph birds are white, usually sparsely flecked with black on the body and wings, and with dark brown eyes. Adult dark morph birds have a mainly dark grey-brown body with an off-white head, neck and upper breast. The wings are mottled greyish-brown with pale feathers along the leading edge. Their eyes are pale grey to whitish. Both morphs have a huge yellowish-horn bill with a pale green tip, and grey-brown legs. When in flight this species has a somewhat hunchbacked appearance.
The Southern giant petrel comes from the Procellariiformes order, which is referred to as tube-nosed seabirds, due to their unique nose structure. They have nasal passages that attach to the upper bill called naricorns. As a member of the Procellariiformes the Northern giant petrel produce a stomach oil made up of wax esters and triglycerides that is stored in the proventriculus. Proventriculus is the narrow glandular first region of a bird's stomach between the crop and the gizzard. This oil is used against predators as well as an energy rich food source for chicks and for the adults during their long flights. Finally, they also have a salt gland that is situated above the nasal passage and helps desalinate their bodies, due to the high amount of ocean water that they imbibe. It excretes a high saline solution from their nose.
Southern giant petrels are pelagic and circumpolar, generally found between subantarctic and Antarctic latitudes from 40°-68°S, with breeding as far south as continental Antarctica. The closest breeding birds in the New Zealand region are is on the subantarctic Macquarie Island. Other island breeding sites (roughly east to west) include Heard, Kerguelen, Crozet, Prince Edward, Marion, Gough, Bouvetøya, South Georgia, South Orkney, South Sandwich, South Shetland, Falkland, Islas Diego Ramirez and Islas Noir.
This petrel feeds on krill, fish and squid by surface-seizing. They also scavenge penguin, albatross, seal and whale carrion. They catch and kill penguins and albatross chicks and other seabirds up to the size of an adult albatross. The males exclude females from the carcasses that they are feeding on.
A Southern giant petrel with chick
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