Yellow-billed Loon

Yellow-billed Loon (Gavia adamsii) is the largest loon and is distinguished by its substantial ivory-yellow bill, which is held at a slightly upward angle. 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 breeds on large Arctic lakes, winters in northern coastal waters and pursues fish underwater with powerful strokes of its rear-set feet. 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).