On The Very Bearable Lightness of Being: Two New Books About Feathers
Color and pattern form the basis of sexual attraction in many species and signal social status and dominence. Many species which undergo more than one pre-basic molt reach sexual maturity before attaining their first basic adult plumage. Researchers have found that a prolonged sub-adult plumage phase protects these young birds from agression by older more experienced males within their group.
Bird Coloration is far too rich to discuss adequately in a short article such as this but I hope that I have whetted your appetite for this subject enough to inspire you to read more. Few areas of study will do as much to advance your birding skills as the study of plumage and molt. These two volumes belong on the shelf of every birder.