Dusky Warbler

Dusky Warbler (Phylloscopus fuscatus) is a small dark brown leaf warbler with buff underparts, a strong pale eyebrow and a fine pointed bill. 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 breeds in East Palearctic taiga bogs, wet meadows and scrub, feeds on insects low in dense vegetation and migrates to South and Southeast Asia for winter. 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).