Avian Pox Photo by Chris Bumbar, Thousand Oaks, CA Two forms of avian pox exist. In the more common form, wart-like growths appear on the featherless areas of the body, such as around the eye, the base of the bill, and on the legs and feet. In the second form, plaques develop on the mucous membrane of the mouth, throat, trachea, and lungs, resulting in impaired breathing and difficulty feeding. Avian pox can be caused by several strains of the pox virus and has been reported in at least 60 species of birds, including turkeys, hawks, owls, and sparrows. The virus can be spread by direct contact with infected birds or contaminated surfaces (e.g., feeders) or by ingestion of contaminated food or water.