Grey Petrel (Procellaria cinerea)

Grey Petrel

Subspecies

Genus	Species	subspecies	Region	Range
Procellaria	cinerea		SO	widespread

Genus

The Procellaria petrels represent a group of large and bulky seabirds that can be placed between the shearwaters of the genus Calonectris and the more fulmarine petrels. Until recently the largest of the Procellaria-species, the White-chinned and the only slightly smaller Spectacled Petrel, were considered to be conspecific. Now they are split into two separate species. Both have a large and strong bills, ivory colored with black sulci between the horny plates and ivory colored ungues, the latter sometimes slightly darker in the Spectacled Petrel. The Westland and Parkinson?s Petrel are also two similar species, of which the latter is a smaller version of the first. Both have ivory colored bills (with a bluish tinge in young birds), with blackish ungues. In the Parkinson’s the black is less extensive than in the Westland. There is no overlap in bill measurements. The Westland Petrel is of the same size as the White-chinned and its culmen is always longer than 47.8 mm. That of the Parkinson?s Petrel not longer than 45.1 mm The bill of the somewhat distinct Grey Petrel is about the size of the larger Procellarias, with the same pattern as the White-chinned and pectacled, but instead of ivory, more pearl-grey. The Grey Petrel’s somewhat lighter bill structure comes close to that of the Calonectris species. Because its somewhat different coloration, habits and structure this species formerly formed a genus of its own: Adamastor. It is now considered to belong to Procellaria.

Physical charateristics

A large ash-grey and white petrel with brownish grey mantle, back, uppertail-coverts and upperwings, and dark grey underwings, contrasting with white belly. It readily plunges from heights of up to 10m and swims underwater using wings. Differs from White-headed Petrel in having dark grey cap, and from other larger petrels and shearwaters in combination of white underparts and wholly dark underwing.

Listen to the sound of Grey Petrel

[audio:http://www.planetofbirds.com/MASTER/PROCELLARIIFORMES/Procellariidae/sounds/Grey Petrel.mp3]

Copyright remark: Most sounds derived from xeno-canto

wingspan min.:	115	cm	wingspan max.:	130	cm
size min.:	48	cm	size max.:	50	cm
incubation min.:	52	days	incubation max.:	61	days
fledging min.:	110	days	fledging max.:	120	days
broods:	1		eggs min.:	1
			eggs max.:	1

Range

Southern Ocean : widespread. This species has a circumpolar distribution between 32-58 degrees South, but somewhat to the north in the Humboldt Current and off the east coast of South America. It breeds on Gough and other islands in the Tristan da Cunha group (St Helena, to UK), Prince Edward and Marion islands (South Africa), Crozet, Kerguelen and Amsterdam islands (French Southern Territories), Campbell and the Antipodes islands (New Zealand), and Macquarie Island (Australia). Its total Pacific Oceanpulation size is Pacific Oceanorly known.

Habitat

The grey petrel is pelagic, returning to nesting islands and coastal cliffs only to breed

Reproduction

Birds return to the breeding colonies in the austral autumn, first appearing in February and March and often flying in to land during diurnal hours. Eggs are laid in late March and early April, and chicks fledge in late September to early December. The asynchrony in fledging dates within sites and years is thought to reflect food scarcity and variability during the winter rather than asynchrony in laying. The age of first breeding is not known. The species typically forages alone or in groups of three or four, but also occaisionally in larger flocks over 50 birds. It nests in burrows on well-drained areas, often dominated by Poa tussock grass, where the ground may be steep.

Feeding habits

Its diet has been documented by once study in which cephalopods were the main prey item, followed by fish remains. Data obtained from seabird bycatch suggest that during the breeding season (austral winter), females forage further north than males, in waters north of the Subtropical Convergence, up to 1,460 km from their colonies on subantarctic islands.

Video Grey Petrel

httpv://www.youtube.com/watch?v=0QCP5H-jtVI

Conservation

Although there are no current trend data, this species is susceptible to introduced mammalian predators, having been extirpated from Macquarie Island by cats and rats, and today it is the most commonly caught bycatch species in longline fisheries in New Zealand waters. Evidence from Gough Island, formerly thought to contain the largest population of this species, suggest that the species is likely to be subjected to considerable predation from introduced mice that are a major predator on other winter-breeding seabirds. The population on the Kerguelen Islands may also be in decline due to fishery bycatch. Based on these data a moderately rapid decline is suspected and as such the species is listed as Near Threatened, but further data are urgently required in order to more accurately assess its population numbers and trends.
In New Zealand waters, it is the most frequently killed species by the tuna-longline fishery (c.45,000 birds in total could have been caught in the last 20 years) and the selective mortality of adult females could be having an disproportionate impact on the breeding population. Substantial incidental mortality has also been recorded in fisheries off Australia, and it may be caught in significant numbers in international waters in the southern Indian Ocean, for which little seabird bycatch information exists. Any additional source of mortality that approaches 300 individuals was predicted to result in a population decline at the Kerguelen Islands, well below the strict minimum of 755 taken in the Patagonian fisheries operating around the islands. Introduced predators on the breeding islands are a further serious threat, for example, cats and black rat Rattus rattus on Crozet and Kerguelen, and, until their fairly recent eradication, cats on Marion Island. Brown rats Rattus norvegicus were eradicated from Campbell Island in 2001. The introduction of rats to Antipodes Island would be a major threat. Cats and Weka Gallirallus australis were probably responsible for extinction from Macquarie Island and brown rat and cats for its near extinction on Amsterdam. On Gough Island, recent evidence has indicated that introduced house mice Mus musculus are a significant predator of winter-breeding seabirds and are driving population declines of at least two species.

Migration

Disperses over Southern Ocean, mostly 25-60 degrees South, but reaching subtropical zone by following cold Humboldt and Benguela Currents.

Distribution map

Grey Petrel distribution range map

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