The aim of this book is to give a general overview of the whole subject of bird migration. After a chapter describing the Earth's climate and ecosystem, the book is divided into three main sections. The first presents the life histories and migratory habits of nine different ecological categories of birds. The second section deals with the course and timing of the flight journeys, flight behavior, fuel economy, flocking, and the hazards from disorientation and predation. The final section covers the ways that birds navigate and shows that this process is still by no means fully understood.