Small, well-marked warbler. Most striking plumage features are the contrasting broad, pale buffy eyebrow and dark crown stripes; otherwise, upperparts rich dark brownish overall (with indistinct streaking), underparts buffy. Juvenile (in summer–autumn) has fine dusky streaks on breast. Favors marshy and scrubby habitats with reeds, brambles, and bushes, usually not in extensive pure reed beds; can be found in drier habitats on migration. Often heard but can be hard to see: prolonged song much like a reed warbler but slightly faster-paced, jerkier, and overall rougher-toned. Gives short, dry “tchrrt” and “chek” calls.