Greylag Goose

Greylag Goose (Anser anser) is a large grey goose with barred upperparts, pink legs and a heavy orange or pink bill. 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 grazes grass and crops around marshes, lakes and estuaries and is the principal ancestor of many domestic geese. 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).