of thought-provoking questions regarding the seasonal disappearance and reappearance of migratory birds. It addresses the curiosity about their routes, the dangers they face during migration, and the importance of understanding these phenomena for conservation efforts. Lincoln emphasizes the long history of interest in bird migrations, referencing ancient observations, and he outlines the extensive research conducted by the Biological Survey which provides the backdrop for the book's exploration of avian migration patterns. This introduction establishes a framework for understanding the complexity and significance of bird migrations in North America. (This is an automatically generated summary.)