This is the 3rd of 12 volumes in a series of handbooks on the world of birds. It provides coverage of birds, from Hoatzin to auks. The introductory chapter is illustrated with detailed plates to complement the text, and deals with such diverse aspects as evolutionary history, anatomy, physiology, migration and systematics. Each chapter covers a different family, headed by a summary box. Photographs illustrate more unusual features, such as courtship behaviour, thermoregulation or feeding techniques. Each chapter is subdivided into sections: systematics; morphological aspects; habitat; general habits; voice; food and feeding; breeding; movements; relationship with man; status and conservation; and a general bibliography. The species account lists names in French, German and Spanish, in addition to scientific and English names. Each species features: its own distribution map indicating resident, breeding and non-breeding ranges; its official status, according to BirdLife International; and the threats facing each species.