In recent years there have been an unprecedented number of reports of songbird mortality. A previously unreported disease in songbirds has also been discovered. Five diseases commonly affect birds that use feeders. Salmonellosis is the most common bird-feeder disease. This is a general term for any disease in animals and people caused by Salmonella bacteria.
Birds get sick when they eat food contaminated by infected droppings.
Trichomoniasis is caused by protozoan parasites and is spread when birds consume contaminated food and water. Aspergillosis is caused by a fungus that grows on damp feed and in the debris beneath feeders. Birds inhale the fungal spores, and the fungus spreads through their lungs and air sacs, causing bronchitis and pneumonia. Avian pox is more noticeable than the other diseases. This viral infection causes wartlike growths on the featherless surfaces of a bird's face, legs, and feet.