Arctic Warbler

The Arctic warbler is a widespread leaf warbler of birch or mixed birch forest near water throughout its breeding range in Fennoscandia and the northern Palearctic, with a foothold in Alaska. It is greyish-green above and off-white below, and its single wing bar distinguishes it from most similar species except the greenish warbler, though it is larger than that species with a heavier, dagger-like bill with a dark tip to the lower mandible (Wikipedia, general species account).

It is strongly migratory, the entire population wintering in Southeast Asia, one of the longest migrations of any Old World insectivorous bird. The nest is on the ground in a low shrub and the song is a fast trill. The cached account does not describe its Indian range. SoIB 2023 lists it as a winter migrant of forest and plantation that eats invertebrates, without a priority category (Wikipedia, general species account; SoIB 2023).