The avian integument consists of highly specialized structures that show extreme variations between species. Feathers are the most obvious part of the integument, and their color and beauty forms an important basis for the attraction of birds to humans. Any disorder in the feathers can be distressing for a client and frustrating for the avian practitioner. The cause of some disorders may be apparent, but others have a complex pathogenesis involving management, human-bird interaction, malnutrition, psychologic factors, disease, or hormone imbalances.