A rather distinctive and bulky warbler: male plain grayish overall with eponymous black cap; female and juvenile plain, slightly browner overall, with rusty-brown cap. Inhabits wooded and scrubby habitats, including gardens, sometimes visiting feeders in the winter. Small numbers winter in Western Europe, but most migratory birds move south to Africa and the Mediterranean region. Song is a varied, rather loud rich warble, often strident. Often gives a harsh “chakchak” call, usually in series. Rare dark morph with black-hooded male and brown-hooded female can be found on the Atlantic Islands and very scarcely elsewhere.