Large seabird of offshore tropical waters. Nests on offshore islands and very rarely seen from mainland. Often found with feeding groups of other seabirds such as terns, other boobies, and shearwaters. Adult is mostly white with a black trailing edge to the wings, black tail, and dark mask at base of stout yellow bill. Immature has brown head, neck, and upperparts with white patches. Immature told from other boobies by pale yellowish bill, mostly white underwings.