A plump bird, with a fine bill and almost continuous flicking of the tail. In the breeding season the males is black on the head, wings, tail and back with a white wing marking, white underparts and forehead. During the rest of the year, the male adopts a female-type plumage, with the black being replaced by brown. They breed in woodland above 1000 metres above sea-level on the slopes of the Gredos mountains, but during passage they can occur almost everywhere. They feed on insects captured on the ground or on aerial sallies from exposed perches.