Trumpeter Swan

Trumpeter Swan (Cygnus buccinator) is North America's largest living waterfowl, entirely white as an adult with a straight black bill and black facial skin. The combination of body shape, bill structure, plumage pattern and voice provides the most useful field characters. Age, sex and season can alter its appearance, so identification should use several features rather than colour alone. This supports comparison with similar species in the field (Wikipedia, general species account).

It feeds on aquatic vegetation in shallow lakes and marshes and builds a large emergent-plant nest near water. Its movements and social behaviour vary through the year, with breeding birds generally more dispersed and non-breeding birds more likely to gather where food is concentrated. Japanese records place it within the country's documented avifauna as a resident, migrant, visitor or introduced bird (Wikipedia, general species account; Wildlife of Japan occurrence records).