Avian illness

July 15, 2021

Question: I’ve been reading articles about the mystery illness affecting birds in the Eastern U.S. We have been seeing birds with the same symptoms around our home in Southern California for months. Crusty eyes, twitchy head movements, disorientation or they do not fly off when approached. Have there been any reported bird deaths in California that could be attributed to the mystery illness?

Answer: While the cause of the illness affecting birds in the eastern U.S. is still being investigated, CDFW’s Wildlife Health Laboratory is closely monitoring two diseases that are known to cause eye disease in wild birds in California. These include avian mycoplasmosis, a bacterial infection, and avian pox, which is a viral infection. Both are transmitted through contact with an infected bird or contaminated surfaces like bird feeders. Avian pox may also be transmitted through a mosquito bite. Avian mycoplasmosis primarily affects house finches and goldfinches and causes swollen, crusty eyes, labored breathing and generalized weakness. A related infection has also been identified in crows. Avian pox causes wart-like growths on the skin often around the eyes and bill. Both infections spread readily at bird feeders and bird baths. If sick birds are seen at feeders, it is recommended the feeders be removed until the outbreak subsides. Thorough, weekly cleaning of bird feeders and bird baths may help reduce transmission. An even better option would be to plant a bird and pollinator friendly garden. Residents can help CDFW monitor for wildlife illness and deaths by submitting a report using CDFW’s online mortality reporting form. Disposable gloves should be worn, and hands should be thoroughly washed after handling of bird feeders and bird baths and when disposing of dead birds.