
Photo: (c) Алексей Логинов, some rights reserved (CC BY) · CC BY 4.0
Branta bernicla
Rare visitor: recorded only occasionally in this country
Brant Goose (Branta bernicla) is a compact dark goose with a black head and neck, small white neck patches and a pale or dark belly. 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 Arctic tundra and winters on coasts, feeding heavily on eelgrass, algae and saltmarsh plants. 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).