Thick-billed Warbler

The Thick-billed Warbler is a 16–17.5cm passerine with an unstreaked brown back, buff underparts, a rounded forehead and a short, pointed bill. Its plain plumage and head shape are useful identification features. It feeds on insects and other small prey. The species account uses Arundinax aedon as the accepted name while listing Acrocephalus aedon as a synonym. (Wikipedia, general species account)

The species breeds in the eastern Palearctic, from southern Siberia to western Mongolia, and migrates to tropical South and Southeast Asia for winter. The account supports this broad migratory distribution but does not provide a sufficiently precise statement of occurrence within China for one to be added here. The entry remains keyed by Acrocephalus aedon because that is the exact scientific name supplied in the CSV. (Wikipedia, general species account)