Ring-necked Duck

Ring-necked Duck (Aythya collaris) is a compact diving duck whose male has a peaked head, white bill rings, grey flanks and a vertical white shoulder spur. 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 breeds on wooded freshwater ponds and dives for plant material and invertebrates, wintering on larger unfrozen waters. 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).