shearwater, common name for members of the family Procellariidae, gull-like sea birds related to the petrel and the albatross and including the fulmar. Shearwaters are found on unfrozen saltwaters all over the world, with 35 species in North America. They have tubular nostrils, hooked bills enlarged at the tip, short tails, and long, pointed wings. They feed on marine animals and oily matter on the open seas, coming to shore only to breed. Shearwaters are 15 to 25 in. (37.5–62.5 cm) long, dark above and light below—except for the grayish-bellied sooty shearwater, Puffinus griseus, of the Pacific, which migrates across the whole ocean region. Most common in the North Atlantic are the greater shearwater and Cory's shearwater. The slender-billed shearwater of Australia, P. tenuirostris, which also migrates over the entire Pacific, is a game bird known also as muttonbird or Tasmanian squab. The two fulmars, one of the North Atlantic and the other, the silver-gray fulmar, of antarctic regions, have thick, stubby yellow bills. Shearwaters are classified in the phylum Chordata, subphylum Vertebrata, class Aves, order Procellariiformes, family Procellariidae.