A fairly rigorous study, but readable, by a French biologist, rendered into English by Peter whitehead. Beginning with a small section on migratory mammals, some of whose populations are now, or have been, decimated by massacres (the bison, the Springbok gazelle, lemmings, bats, etc.) the author devotes most of the book to the spectacular migrations of birds. He traces the common occurrences of migrations in different parts of the world and the patterns of representatives species. Of much more general interest are the sections dealing with migratory behavior, character, environmental factors, physiology of migrating birds and, most fascinating, orientation. The author reviews past and recent experiments--homing studies, work with nocturnal or diurnal migrants. The ""astronomical theory"" is discussed at some length and the author presents his view that perceptions are ""spontaneous"" in orientation and it would be unwise to attribute ""deductive reasoning"" to the creatures' ""mysterious"" response to environment. As for the cause of migration, the author considers it but one factor in equilibrium. Concluding Chapters deal with fish and insects. Specialists may find this study cursory, a bit lop-sided, and a bit dated (the recent work with lemmings is not included).