Gray's Grasshopper Warbler

Gray's Grasshopper Warbler (Locustella fasciolata) is a large plain olive-brown grasshopper warbler with a strong bill, pale underparts and a long graduated tail. 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 dense vegetation in north-eastern Asia, forages for insects near the ground and migrates south to tropical Asia, where it continues to favour thick concealment. 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).