The Sedge Warbler (Acrocephalus schoenobaenus) is an Old World warbler in the genus Acrocephalus. It is a medium-sized warbler with a brown, streaked back and wings and a distinct pale supercilium.
This is a medium-sized warbler, 11.5-13 cm long and weighing around 12 g. It has a streaked brown back and wings, and pale underparts. The rump is warm brown and unstreaked, contrasting with the duller wings. The forehead is flattened, there is a prominent whitish supercilium, the crown is streaked with black, and the bill is strong and pointed. The legs are greyish.
The plumage of the sexes is identical, although they can be told apart when caught for ringing by the presence of a brood patch or cloacal protuberance. Juvenile birds have dark spots on the breast. They can be easier to confuse with Aquatic Warblers due to an apparent pale central crown stripe contrasting with the darker edges. Other similar species include Moustached Warblers and Pallas’s Grasshopper Warblers.
It breeds across Europe and western and central Asia and is migratory. After feeding up post-breeding, they migrate quickly across southern Europe and the Sahara from August to September. Studies in Nigeria and Uganda suggest that Sedge Warblers return to spend winter at the same sites, year after year.