Great Shearwater
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| Great Shearwater | ||||||||||||||
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| Puffinus gravis (O'Reilly, 1818) |
The Great Shearwater (Puffinus gravis) is a large shearwater in the seabird family Procellariidae.
This species breeds on Nightingale and Inaccessible Islands, Tristan da Cunha, and on Gough Island. It is one of only a few bird species to migrate from breeding grounds in the Southern Hemisphere to the Northern Hemisphere, the normal pattern being the other way round.
This shearwater follows a circular route, moving up the eastern seaboard of first South and then North America, before crossing the Atlantic in August. It can be quite common off the south-western coasts of Great Britain and Ireland before heading back south again, this time down the eastern littoral of the Atlantic.
This bird has the typically "shearing" flight of the genus, dipping from side to side on stiff wings with few wingbeats, the wingtips almost touching the water. Its flight is powerful and direct, with wings held stiff and straight.
This shearwater is 43-51 cm in length with a 105-122 cm wingspan. It is identifiable by its size, dark upperparts, and underparts white except for a brown belly patch and dark shoulder markings. It has a black cap, black bill, and a white "horseshoe" on the base of the tail. The stiff flight, like a large Manx Shearwater, is also distinctive.
The Great Shearwater feeds on fish and squid, which it catches from the surface or by plunge-diving. It readily follows fishing boats, where it indulges in noisy squabbles. This is a gregarious species, which can be seen in large numbers from ships or appropriate headlands.
The Great Shearwater breeds in huge colonies, nesting in burrows which are visited only at night to avoid predation by large gulls.nl:Grote pijlstormvogel