Book excerpt: We share the earth with a wide variety of animal species, each of which brings something special to the diversity of the planet. By knowing more about how animals behave and live, we gain a greater understanding of how life evolved and the importance of biodiversity. This volume provides a complete guide to those birds that have evolved a trait that would seem to harm their ability to survive - flightlessness. Flight has its advantages - why would some birds be flightless? Flightless Birds covers the loss of flight in birds, both permanently after years of evolution, and temporarily as a result of unusual molting behavior, and those species that are in various stages of losing their flight. The book provides a thorough guide, perfect for research papers in biology classes, for understanding the behavior and biodiversity of a fascinating and unusual group of animals. Flightless Birds includes sections on the major groups of flightless birds: Rarities whose ancient ancestors were on the continents when they broke away millions of years ago, and who survived despite competing with mammals; birds that were marooned on islands in the ocean, where food was plentiful and predators absent; penguins, which evolved alongside seas teeming with food and had no need to fly, and the special case of New Zealand's many flightless species which evolved in a predator-free paradise but could not cope with the settlers and their alien animals; and the many species which have become extinct within historic times. Beautifully illustrated, with numerous color photos, Flightless Birds provides copious material for understanding these unusual animals.