Brown Booby

Brown Booby (Sula leucogaster) is a robust tropical seabird with brown upperparts and head sharply contrasting with a white belly. Body shape, bill structure, plumage pattern and voice provide the strongest field characters. Age, sex and season may alter its appearance, so identification should combine several features and careful direct field comparisons with similar species in the same habitat (Wikipedia, general species account).

It flies low over warm inshore waters and plunge-dives for small fish and squid, while breeding pairs establish ground nests on islands and other undisturbed coastal sites. Its movements and social behaviour vary through the year, with breeding birds generally more dispersed and non-breeding birds gathering where food is concentrated. Japanese records place it within the country's documented avifauna as a resident, migrant or visitor (Wikipedia, general species account; Wildlife of Japan occurrence records).