Pallas's Gull

Pallas's Gull (Ichthyaetus ichthyaetus) is a very large gull with a black breeding hood, heavy yellow-and-red bill and broad white wing panels. 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 comparisons with similar species in the same habitat (Wikipedia, general species account).

It breeds on inland Asian lakes and winters along southern coasts, taking fish, invertebrates, carrion and other birds' eggs. 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).