The Grey Petrels, Procellaria cinerea, also called the Brown Petrel, Pediunker or Grey Shearwater is a species of seabird in the Procellariidae family. It occurs in the open seas of the Southern Hemisphere, mainly between 49°S and 32°S.
Description
The Grey Petrel is a large grey, white, and brown petrel. They average 48 cm (19 in) in length and weigh 1,000 g (35 oz). They have brownish-grey mantle, back, upper tail coverts, and upper wings. They have a white belly and underwings and under-tail that are ash-grey. They have a yellow-green bill and pink-grey feet.
Feeding
They will dive from heights up to 10 m (33 ft) when getting food. It breeds on Tristan da Cunha, Gough Island, the Prince Edward Islands, Crozet Islands, Kerguelen Islands, and New Zealand on the Campbell Islands and Antipodes Islands.
Breeding
Grey Petrels return to their breeding grounds in February and March and build a burrow for a nest. These burrows are on well-drained ground, overrun with Poa tussock grass, typically on steep terrain. By late March or early April, they lay their one egg, with both birds incubating it. After hatching, the chick is cared for by both birds until it fledges from late September to early December.
Range and habitat
Grey Petrels are pelagic and typically stay within 49°S and 32°S during non-breeding season. During the breeding season, they form colonies on several islands.
Antipodes Island, with an estimate of 53,000 pairs, and Gough Island with 10,000 pairs are the biggest colonies, with others on Prince Edward Island, Marion Island, Tristan da Cunha, Crozet Islands, Kerguelen Islands, Amsterdam Island, Campbell Island, New Zealand, and Macquarie Island. They have an occurrence range of 68,800,000 km2 (26,563,829 sq mi).
| Location | Population | Date | Trend |
| Gough Island | 10,000+ pair | 2004 | Decreasing |
| Total Tristan da Cunha | 10,000+ pair | 2004 | |
| Marion Island | 1,600 pair | ||
| Prince Edward Island | 2,000—5,000 pair | ||
| Kerguelen Islands | 2,000—5,000 pair | ||
| Crozet Island | 2,000—5,000 pair | ||
| Amsterdam Island | 10 pair | ||
| Campbell Island, New Zealand | 100—600 pair | ||
| Macquarie Island | 59—80 pair | Declining | |
| Antipodes Island | 53,000 pair | 2001 | Declining |
| Total Adults | 400,000 | 2004 | Decreasing |
Conservation
There is not a lot of recent information about this bird, but its population is believed to be shrinking slowly at least possibly rapidly. Introduced predators such as Domestic Cats, Rattus norvegicus, and Rattus rattus are contributing to the decline, as well as longline fishing, which is a major problem.
This bird is the most commonly caught by-catch by longline fisheries in New Zealand waters, with one estimated at 45,000 birds in the last 20 years. Other predators, such as Gallirallus australis, and Mus musculus.
To assist in maintaining or increasing its population, it has been placed on CMS Appendix II, and Agreement on the Conservation of Albatrosses and Petrels (ACAP Annex). Gough Island has been designated as a World Heritage site.
Antipodes Island has had preliminary work done to start long-term monitoring, and in 2007 the monitoring started. In 2001, Rattus norvegicus was eradicated from Campbell Island, and in 2006, the South East Atlantic Fisheries Organisation (SEAFO) tightened longline regulations.
In the future, numerous tasks are planned, starting with a census of all the breeding locations. Also, studies on Gough Island about Mus musculus, and finally, stricter fishing regulations enforced by FAO, RFMO, and Agreement on the Conservation of Albatrosses and Petrels (ACAP).
Taxonomy
The Grey Petrel is a member of the Procellaria genus, and in turn, is member of the Procellariidae family, and the Procellariiformes order.
As a member of the Procellariiformes, they share certain identifying features. First, they have nasal passages that attach to the upper bill called naricorns. Although the nostrils on the Prion are on top of the upper bill.
The bills of Procellariiformes are also unique in that they are split into between 7 and 9 horny plates. They produce a stomach oil made up of wax esters and triglycerides that are stored in the proventriculus (stomach). This is used against predators as well as an energy-rich food source for chicks and 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.
Etymology
Procellaria comes from two Latin words, procella meaning a storm, and arius a suffix meaning about. This is about their association with stormy weather. The word Petrel is derived from St. Peter and the story of his walking on water. This is about the Petrels habit of appearing to run on the water to take off.
