Thick-billed Warbler

The thick-billed warbler is a large warbler 16–17.5 cm long, nearly as big as the great reed warbler. The adult has an unstreaked brown back and buff underparts with few distinctive plumage features, a rounded forehead and a short pointed bill; the sexes are identical, but young birds are richer buff below. It breeds in the temperate east Palearctic from south Siberia to west Mongolia and is migratory, wintering in tropical South and Southeast Asia (Wikipedia, general species account).

Five or six eggs are laid in a nest in a low tree. Like most warblers it is insectivorous but will take other small prey. The song is fast and loud, like the marsh warbler's, with much mimicry and typically acrocephaline whistles. SoIB 2023 rates it a Moderate conservation priority, a winter migrant of non-specialised habitat with a Moderate range of about 119,000 km² and a decline of about 46% over the long term (Wikipedia, general species account; SoIB 2023).