The appearance of these birds is very varied, but they mostly have weak songs and harsh calls. They are small to medium birds, ranging from 9 to 22 cm in length. Many species are dull brown in colour, but the plumage of some can be much brighter, especially in the males. Most have broad, flattened bills suited to catching insects in flight, although the few ground-foraging species typically have finer bills. Old World flycatchers live in almost every environment with a suitable supply of trees, from dense forest to open scrub, and even the montane woodland of the Himalayas. The more northerly species migrate south in winter, ensuring a continuous diet of insects. Depending on the species, their nests are either well-constructed cups placed in a tree or cliff ledge, or simply lining in a pre-existing tree hole. The hole-nesting species tend to lay larger clutches, with an average of eight eggs, rather than just two to five.