Yellow-browed Warbler

Yellow-browed Warbler (Phylloscopus inornatus) is a tiny green leaf warbler with a bright pale eyebrow, two strong wing bars and pale edging on the tertials. 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 across the eastern Palearctic, forages restlessly for insects in trees and shrubs and migrates mainly to tropical South and Southeast Asia, with smaller numbers travelling west into Europe. 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).