Bill and legs greenish to yellow. Adult dark brown with sharply contrasting white breast and belly; under wing-coverts also white. Immature mostly dark grayish brown but already with an indication of adult's pattern below (throat and chest distinctly darker than breast and belly). Adult males of Pacific race (etesiaca) have white forehead, darkening on forecrown.
Habits and Behavior
Looks tapered at all ends, with long pointed bill, narrow pointed wings, and long wedge-shaped tail. Sails on rather stiff outstretched wings, usually rather low over the water, much like a large shearwater. Often attempts to fly off with bait being trolled behind fishing boats; occasionally one becomes hooked and must be hauled in to be released.