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. However, in this edition, new examples are introduced throughout, many illustrated with full colour 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 aided by boxed sections illustrating important concepts and new marginal notes which guide the reader through the text. This book will be essential reading for students taking courses in behavioural ecology.