This work is designed for a one-semester introductory course in Animal Behavior. Animal behavior is a broad discipline with investigators and contributions from diverse perspectives, including anthropology, comparative psychology, ecology, ethology, physiology, and zoology. The author's goal in this textbook is to use evolutionary principles as a unifying theme to provide students exposure to a number of approaches to the field of animal behavior. They also demonstrate that the varied perspectives used to study behavior are complementary and often integrated; they are not mutually exclusive. The subtitle, "Mechanisms, Ecology, and Evolution," reflects the broad themes that dominate the book.