Seven years have elapsed between this and the preced- ing major symposium on animal orientation and naviga- tion, held on Wallops Island, Va., USA in 1970. Never before between two symposia in this field has there been such an enormous increase - more truly an explo- sion - of new data, new evidence, new ideas, and meth- ods. Moreover, environmental awareness has also in- creased tremendously. The essential role of animals as bio-indicators, the economic importance of dwindling stocks of fish, whales, and other animals demand in- creasing efforts to investigate their life cycles and whereabouts, and that means for many of them, their travels between breeding, feeding, or wintering ranges. Although many aspects of research in the various fields covered by this symposium qualify as basic research, environmental and economic considerations cannot be dismissed. Finally, there is a chance to eventually find biologic systems of migration and orientation that may be at least partially useful for human navigation or other undertakings. The diversity of species involved in animal migration and the methodologies employed in unraveling the modes of animal navigation provide the reader of this volume with a survey of the front line of research in this field, with emphasis on current ideas and with a fore- taste of the problems ahead. The reports offer insight into the experimental difficulties, sometimes formi- dable, that the researcher encounters when dealing with free-ranging animals.