دانلود کتاب Bird Migration

The phenomenon of bird migration has fascinated people from time immemorial. The arrivals and departures of different species marked the seasons, heralding spring and autumn and providing a reliable calendar long before anything better became available. Migration is shown by many kinds of animals, including butterflies and other insects, mammals, marine turtles, and fish, but in none is it as extensively developed as in birds. The collective travel routes of birds span almost the entire globe, with some extreme return journeys covering nearly 20,000 miles. As a result of migration, bird distributions are continually changing—in regular seasonal patterns as well as on local, regional, or global scales. Migration has repeatedly prompted familiar questions, such as where birds go or come from, why they do it, how they know when and where to travel, and how they find their way. In this seminal new book, Ian Newton sets out to answer these questions and more. The book is divided into four main sections: the first is introductory, describing the different types of bird movements, methods of study, and the main migration patterns seen around the British Isles. The second part is concerned mainly with the process of migration—the timing, energy needs, weather effects, and navigation. The third covers evolution and change in migratory behavior, and the fourth examines the geographical and ecological aspects of bird movements.