The bowerbirds are unique in the avian world in that the males build elaborate 'bowers': structures of sticks, grasses or other plant stems on or close to the ground, often incorporating objects such as colourful fruits, flowers, feathers, bones, stones, shells, insect skeletons, and numerous other natural (and human-made) objects. The highly sophisticated building, decorating, arranging, singing, and courtship posturing and dancing by males is primarily to attract and impress females. As much of it is performed in the absence of females, however, some consider it possible that males may also enjoy such activities for their own sake. The bowers and the birds' behaviour associated with them have been much studied by behavioral ecologists searching for evolutionary and ecological explanations of behavioural patterns. The Bowerbirds is an indispensable work of reference for everyone interested in these birds.