Adult birds are white with dark brown or black flight and tail feathers. Bill color is yellow and feet are yellowish gray. Facial skin is gray-black. Sexes are similar in appearance. Juveniles are generally grayish brown with white underparts.
Adult plumage is attained by the third year.
Midway Population Masked Boobies nest in small numbers at Midway and no historical information indicates that they were previously more numerous. There are generally less than five nesting attempts per year. Feeding Habits Feeds by plunging head first into the water from the air, sometimes diving from as high as 30m. Feeding areas are usually many miles from land. Feeds primarily on fish and squid.