Tinbergen asked four general questions about animal behavior-causation, ontogeny, survival value, and evolution. In this book, authors Michael J. Ryan and Walter Wilczynski use these questions to explore basic concepts such as the function, evolution, and mechanism of behavior. Then the neurological and endocrine mechanisms of search for resources are described, using as examples foraging, sensing, finding, and deciding, orientation and migration. The biological mechanisms and evolutionary significance of social behavior are discussed through the examples of sex differences, mate choice, social bonding, cooperation, conflict, and aggression. This book provides a well-thought-out introduction to the complexity of animal behavior that will appeal to advanced undergraduates, graduate students, and professional scientists in other fields.