GANNET, or SOLAN GOOSE, Sula bassana, a large sea-bird. It breeds in enormous numbers in certain stations in the north Atlantic (of which the Bass Rock in the Firth of Forth, and Bird Rock in the Gulf of St. Lawrence, are the most famous), arriving about the end of March and leaving again in the autumn. During the non-breeding season it ranges over the whole of the north Atlantic.
The plumage in both sexes is white, with the outer edge of the wing black and some bare patches of dark blue skin round the eye. The young are clad in brown, white-tipped feathers. The nest is a shallow depression, usually in a mass of grass and seaweed. The single egg is white, and the young are hatched blind and naked. Striking mutual courtship ceremonies are performed. The gannet feeds on fish, which it obtains by plunging into the water with closed wings, often from a considerable height. Fish ermen tow a board with a herring painted on it below the surface of the water; the bird dives, strikes the board and breaks its neck.
The most remarkable structural features of the gannet are the closed nostrils, the aborted tongue and the system of subcutaneous air-spaces, which communicate with the lungs, and can be filled or emptied at will. These latter probably break the force of its plunge.
In the southern hemisphere are two smaller forms, S. capensis of South Africa and S. serrator of Australia, while the tropical boobies, comprising four species, also belong here. One, S. varie gata, from Peru, retains its spotted plumage throughout life and is one of the guano birds.
To the same genus belong the boobies, including the booby gannet (S. leucogastra) of tropical and subtropical seas through out the world, and Brewster's booby (S. brewsteri) on the Pacific coast of North America.