To most observers, molt seems an overwhelming subject. But birders use many aspects of molt more than they realize to distinguish juvenile birds from adults, to pick out an individual hummingbird from among dozens visiting a feeder, and much more.And for those whose interest goes beyond simply identifying birds, questions such as What triggers molt to start? How fast do feathers grow? and How long do they last? offer a fascinating window into the lives of birds. Put plainly, molt relates in some way to everything a bird does, including where it lives, what it eats, and how far it migrates.Here, for the first time, molt is presented for the nscientist. Molt is very orderly and built on only four underlying strategies: simple basic, complex basic, simple alternate, and complex alternate. This book clearly lays out these strategies, relates them to aspects of life history, such as habitat and migration, and makes this important subject accessible.