Trichomonas gallinae causes avian trichomoniasis. When present, it is usually found in the upper digestive tract of many species of doves and gallinaceous birds. Some strains may also produce liver and lung lesions. The presence of this organism in doves is a common source of infection of falcons and hawks feeding on them. In addition to showing signs of general illness, for example lethargy and fluffed-up plumage, affected birds may drool saliva, regurgitate food, have difficulty in swallowing or show laboured breathing.