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Giant petrel

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Giant petrels are massive seabirds belonging to the genus *Macronectes*. This name comes from Ancient Greek words meaning "great swimmer."

Giant petrel
Giant petrel

They are the largest members of the family Procellariidae. Unlike most other birds in this family, giant petrels have strong legs. This allows them to walk on land. They are often found in the Southern Hemisphere. Some individuals have even been found as vagrants in Europe.

These birds are highly opportunistic and aggressive. They serve important roles as both predators and scavengers in their ecosystems.

To survive in harsh marine environments, giant petrels have developed several specialized biological mechanisms. Their bills are split into seven to nine horny plates. They possess a hooked bill called a maxillary unguis. This structure helps them grip slippery prey like fish or squid.

They also produce a specialized stomach oil made of wax esters and triglycerides. This oil is stored in a part of the stomach called the proventriculus. The birds can spray this oil from their mouths. They use it to defend themselves against predators. They also use it as a protein-rich food source for their chicks. Additionally, they have a salt gland located above the nasal passage. This gland helps them desalinate their bodies by excreting a high saline solution from their noses.

There are two living species of giant petrels that scientists study today. The first is the northern giant petrel, known as *M. halli*. The second is the southern giant petrel, known as *M. giganteus*. They were long considered the same species. However, they were established as separate species in 1966.

Giant petrel with chicks
Giant petrel with chicks

These two species, along with two species of fulmars, form a distinct subgroup within the Procellariidae family. This group also includes the Antarctic, Cape, and snow petrels. An extinct species, *Macronectes tinae*, also once belonged to this genus. This fossil bird lived during the Pliocene epoch in New Zealand.

Distinguishing between the two living species requires looking at specific physical details. The southern giant petrel is the larger of the two. It has a wingspan of 185 cm and a body length of 75 cm. The northern giant petrel is smaller, with a 165 cm wingspan and a 60 cm body length.

Their plumage is mostly mottled grey. However, about 15% of southern petrels are almost completely white. You can also tell them apart by their bills. The billtip of *M. halli* is reddish-pink. The billtip of *M. giganteus* is pale green. Adults of the northern species typically have pale eyes. Adults of the southern species usually have dark eyes.

History shows how our understanding of these birds has evolved. The genus *Macronectes* was introduced in 1905 by the American ornithologist Charles Wallace Richmond. He created the name to accommodate the southern giant petrel. Before this, the name *Ossifraga* was used. However, that name was later found to belong to a different group of birds. The name "petrel" itself comes from the story of St. Peter walking on water. This refers to how the birds seem to run on the water surface when taking off.

Giant petrels are famous for their aggressive feeding behaviors. They are often called "stinkers" or "glutton birds" by sailors. On land, they scavenge carcasses in penguin and seal colonies. They use a "sealmaster posture" to show dominance over food. In this pose, they hold their head and wings outstretched. They even kill other seabirds, including large albatrosses, by battering or drowning them.

Giant petrel
Giant petrel

At sea, they hunt krill, squid, and fish. They are also known to follow fishing boats to eat offal and waste.

Reproduction for these birds is a slow and careful process. Both species lay a single egg in a rough nest near the ground. The egg is incubated for about 60 days. Once the chick hatches, it is brooded for three weeks. The chicks fledge after about four months. However, they do not reach sexual maturity for six or seven years after fledging.

Giant petrel with chicks
Giant petrel with chicks

While they were once listed as near threatened, recent data suggests populations are increasing. They are currently listed as "least concern" by the IUCN. However, conservation laws in Australia still list them as vulnerable or endangered depending on the state.

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🖼️ Images & Media (3)
File:Fish8556 - Flickr - NOAA Photo Library.jpg
Fish8556 - Flickr - NOAA Photo Library.jpg
File:Giant petrel.jpg
Giant petrel.jpg
File:Giant petrel with chicks.jpg
Giant petrel with chicks.jpg
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