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Greater Shearwater Puffinus gravis

Greater Shearwater by Marie C. Martin, CUNY

Field marks: Large shearwater 45-53 cm (18-21 inches) head-to-tail length, black-billed, black-capped shearwater. Underparts mostly white except for undertail coverts and a distinctive blackish-brown belly smudge. Strong flyer with powerful and quick wing-beats.

Primarily May through early July, but can occur in other seasons. Most of the birds present during the summer are young birds as the adults 'winter' farther north. Common, often abundant, during migration off Bermuda.Uncommon in the Gulf of Mexico, off the Bahamas, and Puerto Rico, and likely to occur sporadically elsewhere in the West Indies.

Natural History: Trans-equatorial migrant endemic to the Atlantic Ocean with three primary breeding populations: Nightingale, Inaccessible, and Gough Island in the south-central Atlantic. Several million breeding pairs occupy each of these sites. Every few years, there is a massive die-off of Greater Shearwaters from the Bahamas to the Virginia Coast. Lee (2007) proposes that the young birds are challenged to cross the doldrums around the equator if the winds are particularly weak during migration. These young birds arrive in the Caribbean and Southeastern United States exhausted and starving, with many dying and washing up on beaches. The adults migrate prior to the young, generally missing the worst effects of the doldrums.

West Indian Breeding Seabird Atlas by Will Mackin and David Lee is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License. Based on work at www.wicbirds.net. Permissions beyond the scope of this license may be available at www.wicbirds.net.

Suggested Citation: Lee, D. S., W. A. Mackin. 2012. Greater Shearwater. West Indian Breeding Seabird Atlas <http://www.wicbirds.net/grsh.html>. Last Updated: _____. Date accessed: ______.

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February 24, 2012
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