Eurasian Wren

Eurasian Wren (Troglodytes troglodytes) is a tiny russet-brown bird with fine dark barring, a pale eyebrow, thin bill and very short tail commonly held upright. 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 inhabits dense undergrowth, rocky places and woodland across the Palearctic, searching crevices for insects and spiders and producing a remarkably loud song from low cover. 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).