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Grey Petrels aka Brown Petrels, Pediunkers or Grey Shearwaters

Petrels

The Grey Petrel, 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 weighs 1,000 g (35 oz). They have brownish-grey mantle, back, uppertail coverts, and upperwings. They have a white belly, and underwings and under-tail that are ash-grey. They have a yellow-green bill and a 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 in 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 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).

Breeding Population and Trends
LocationPopulationDateTrend
Gough Island10,000+ pair2004Decreasing
Total Tristan da Cunha10,000+ pair2004
Marion Island1,600 pair
Prince Edward Island2,000—5,000 pair
Kerguelen Islands2,000—5,000 pair
Crozet Island2,000—5,000 pair
Amsterdam Island10 pair
Campbell Island, New Zealand100—600 pair
Macquarie Island59—80 pairDeclining
Antipodes Island53,000 pair2001Declining
Total Adults400,0002004Decreasing


Conservation

There is not a lot of recent information about this bird, but its population is believed to be shrinking slowly at least and 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 estimate 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, South East Atlantic Fisheries Organisation (SEAFO) tightened longline regulations.

In the future, numerous tasks are planned , starting with a census on all the breeding locations. Also, studies on Gough Island pertaining to 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 is stored in the proventriculus (stomach). This 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.


Etymology

Procellaria comes from two Latin words, procella meaning a storm and arius a suffix meaning pertaining to. This is in reference to their association with stormy weather. The word Petrel is derived from St. Peter and the story of his walking on water. This is in reference to the Petrels habit of appearing to run on the water to take off.


Copyright: Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from Wikipedia.org ... Additional information and photos added by Avianweb.



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