The third edition of this successful textbook looks again at the influence of natural selection on behavior - an animal's struggle to survive by exploiting resources, avoiding predators, and maximizing reproductive success. In this edition, new examples are introduced throughout, many illustrated with full color photographs. In addition, important new topics are added including the latest techniques of comparative analysis, the theory and application of DNA fingerprinting techniques, extensive new discussion on brood parasite/host coevolution, the latest ideas on sexual selection in relation to disease resistance, and a new section on the intentionality of communication. Written in the lucid style for which these two authors are renowned, the text is enhanced by boxed sections illustrating important concepts and new marginal notes that guide the reader through the text. This book will be essential reading for students taking courses in behavioral ecology. The leading introductory text from the two most prominent workers in the field. Second colour in the text. New section of four colour plates. Boxed sections to ilustrate difficult and important points. New larger format with marginal notes to guide the reader through the text. Selected further reading at the end of each chapter.