How can we explain the peacock.s beautiful tail decorations, or the wonderful song of the nightingale? Why are some smells nice and others nasty? How do animals signal their intentions and qualities to potential partners? How do offspring tell parents about their needs? Are signals tuned to the environment, and to the mental abilities of receivers? Are colours, sounds and smells informative of health, parental capacity, or genetic quality? Essential for understanding how animals cope with their ecological and social environment, the study of animal signals is one of the most active research areas in modern evolutionary biology. Understanding the signalling systems of nature has wide-ranging relevance including biological conservation and human communication. Animal Signals provides a state-of-the-art update on current knowledge within this rapidly developing field. Written by leading international scientists, it provides a comprehensive overview of the fascinating diversity of animal signals and signalling functions. Combining reviews and novel research, the book is aimed both at students and professional scientists.