Black-throated Loon

Black-throated Loon (Gavia arctica) is a large loon with a black throat, grey head and a conspicuous white patch on the rear flank 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 breeds on northern freshwater lakes, winters mainly along coasts and feeds largely on fish captured during underwater pursuit dives. 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).