Note from the editor :

Every year countless millions of animals leave the areas in which they have lived for many month and embark on hazardous journeys to new regions, returning to their original homes the following spring. This is the classical image of migration. But the tem can equally be applied to the displacement of the spores and seeds of plants and to the dispersal, emigration, nomadic movement and explorations or animals, including man. This book explains why and how life migrates and also introduces new theories of migration.