Cetti's warbler (Cettia cetti) is a small, brown bush-warbler which breeds in southern and central Europe, northwest Africa and the east Palearctic as far as Afghanistan and northwest Pakistan. The sexes are alike. This species is very difficult to see because of its skulking habits.
Cetti's warbler has a rounded head with a narrow pale grey stripe arching over conspicuous black eyes, and short, rounded wings. The upperparts are a rich chestnut or dark reddish-brown; the throat and breast are pale grey. The tail is longer and broader than many other warblers. The birds can be aged by their plumage; juveniles look similar to adults but have fresh plumage and two dark or dark grey spots on the tongue. Cetti's warbler is unusual among passerine birds in having ten tail feathers (rectrices) rather than the usual twelve.
Cetti's warblers signal their presence with loud song. Their song is distinct, comes in loud bursts, and has a unique structure that allows the birds to avoid mating with other species.