White-rumped Munia

White-rumped Munia (Lonchura striata) is a small brown estrildid finch with finely streaked upperparts, a dark conical bill and a conspicuous white rump. 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 is native to tropical continental Asia and nearby islands and naturalised in parts of Japan, travelling in flocks through grass and scrub to eat seeds; its domesticated descendant is the society finch. 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).