A fairly chunky and recognisable warbler. The male is mostly grey with a distinctive black cap, while the female and juvenile are plainer and slightly browner, showing a warm brown cap. It occupies wooded and scrubby areas, including gardens, and may visit feeders during winter. A few birds remain in Western Europe through the colder months, but most migrants head to Africa and the Mediterranean. The song is a rich, varied warble that can sound quite forceful, and it often gives a repeated harsh “chak-chak” call. A rare dark form, with a black-hooded male and brown-hooded female, occurs on some Atlantic islands and only very occasionally elsewhere.