Dark, long-tailed, long-billed wetland warbler. There is a small white shoulder mark and heavy streaking and spotting on the underparts. Found in papyrus swamp. Shy and difficult to see; most often detected by voice. Song starts with slow and hesitant notes, speeds up, then ends with a trill made by beating the wings together at incredible speed. The white shoulder and heavily streaked breast separate it from reed warblers and other swamp warblers.