Striking large shearwater with distinctive dark "M" pattern on upperwings. Also note crisp dark cap and clean white underwings and belly. Looks silvery-gray above when fresh, but worn birds can be more brownish. Graceful flight style. Usually easily separated from other shearwaters by wing pattern. Breeds on islands off New Zealand; ranges across the Pacific during nonbreeding season; uncommon off the west coast of the U.S. in fall. Rarely seen from land, prefers to stay offshore. Found singly or in flocks with other shearwaters.