This collection of essays was written by former students, associates, admirers, critics and friends of Donald R. Griffin -- the creator of cognitive ethology. Stimulated by his work, this volume presents ideas and experiments in the field of cognitive ethology -- the exploration of the mental experiences of animals as they behave in their natural environment during the course of their normal lives. Cognitive Ethology discusses the possibility that animals may have abilities to experience, communicate, reason, and plan beyond those usually ascribed to them in a "black box" or "stimulus-response" interpretation of their behavior. Contributions from scientists who have been associated with or influenced by Griffin offer a lively array of views, some disparate from one another and some especially selected to present approaches contrary to his.