Ancient Murrelet

Ancient Murrelet (Synthliboramphus antiquus) is a small black-and-white auk with grey back, yellow bill and white head plumes in breeding plumage. 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 dives for small fish and crustaceans and nests in island burrows; chicks leave for sea soon after hatching. 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).