Lanceolated Warbler

Lanceolated Warbler (Locustella lanceolata) is a tiny brown grasshopper warbler marked with narrow spear-shaped dark streaks across its back, breast and flanks. 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 thick Palearctic grassland and shrubby wet vegetation as far east as northern Hokkaido, stays close to the ground while feeding on insects and migrates to Southeast Asia. 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).