Modern students of animal behavior, among whom Dr. Tinbergen is a leader, have repeatedly shown that relatedness of different animal species is just as surely expressed by comparing their behavior patterns as by comparing their body forms.
Being comparative, behavior study is not a field for the narrow specialist. Dr. Tinbergen's distinguished work includes analysis of the homing of wasps, the courtship of butterflies and the nesting behavior of sea birds. His wide experience and deep insights are here combined in a fascinating volume which constitutes not only a challenge but an encouragement to every reader. Anyone, Dr. Tinbergen seems to say, with a sharp eye and ear, a measure of patience and a healthy skepticism about jumping to conclusions, can profitably study animals and may conceivably make observations of lasting value to science. [From the Introduction to the 1st edition]