Sooty Tern

Sooty Tern (Onychoprion fuscatus) is a long-winged tropical tern with black upperparts, white underparts and a white forehead contrasting with black crown. 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 feeds far offshore on small fish and squid and returns to islands in immense, noisy breeding colonies. 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).