Migration on Wings

Birds have been an object of human emotions, admiration, fascination, inspiration, and, of course, envy. Humans have always marveled at their ability to take to the skies and in some cases, seemingly effortlessly carry out seasonal migrations over unimaginably long distances. Birds are an engineer’s dream. Millions of years of evolution have perfected these flying machines. Their extremely light weight bone structure is essential to keeping them airborne. Their wings generate both thrust and lift, a feat that human-built flying contraptions had great difficulty imitating. They are not only ideally suited to flapping and in many cases soaring flight, but can be folded and stowed away into a compact package after the flight. Their flight muscles are adept at converting body fat directly into mechanical energy for flight. The eggs they use for propagation of their species are themselves an engineering marvel: extremely light weight but incredibly strong shell structures that enable the chicks inside to develop in safety. They are constructed such that they contain the nutrients necessary without leakage, yet permit diffusion of oxygen into the egg. Birds have also been the inspiration for human’s successful effort to build heavier-than-air flying machines that have revolutionized the way we travel. But by far, the most fascinating aspect of birds is their ability to migrate nonstop very long distances to their breeding grounds during summer, and to warmer regions during winter. Only recently have man-made jet planes been able to fly similarly long distances without refueling. This book is an effort to explore the technical aspects associated with bird flight and migration on wings. We will first explore the aerodynamics and energetics of long-range migration of birds. We will follow this up by examining the similarities between man-made and natural fliers, and the underlying universal scaling that yields the Great Flight Diagrams.