Be Sure to Clean Bird Feeders Whenever You See House Finch Eye Disease (aka conjunctivitis)

by Matthew Young on Dec 16 2025
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    House finch eye disease, also known as mycoplasmal conjunctivitis, is a bacterial infection caused by Mycoplasma gallisepticum that causes swollen, red, and crusty eyes in house finches and other birds. To reduce its spread, regularly clean bird feeders and baths with a 10% bleach solution, remove old seed, and consider taking down feeders for a couple of weeks if you observe sick birds.

    house finch eye disease

    House Finch Eye Disease Symptoms

    • Swollen, red, and watery eyes
    • Crusts forming around the eyes
    • Runny nasal discharge
    • Difficulty seeing or flying
    • Listlessness, fluffed-up appearance, and approachability

    Causes and Transmission

    • The disease is caused by the bacteria Mycoplasma gallisepticum.
    • It is highly contagious and spreads through direct contact with infected birds or contaminated surfaces at bird feeders and roosts.
    • Crowding at feeders can increase the rate of transmission.

    How to Help

    • Clean your feeders regularly!
    • Wash feeders with soap and water, rinse thoroughly, and then soak or spray them with a 10% bleach solution (1 part bleach to 9 parts water) for at least 10 minutes.
    • Rake and shovel waste seed and droppings on the ground every few days in the summer or shovel fresh snow over them in the winter.
    • Temporarily remove feeders for a week or two if you see sick birds on consecutive days. This allows for the sick birds to disperse and for you to clean the feeders thoroughly.
    • Do not try treat birds yourself! If you know of a licensed wildlife rehabilitator, and you find a severely affected bird, contact a rehabilitator for guidance. If the wildlife rehabilitator takes birds, not all do, take the bird there so they can be legally treated. Some will treat the birds with antibiotics and supportive care, and some birds can be released back into the wild after treatment.

    FAQ

    Can humans get house finch eye disease?

    It is exclusively avian, and so, no, humans cannot get house finch eye disease. The conjunctivitis, caused by a strain of Mycoplasma gallisepticum, is specific to birds and poses no known health threat to people or non-avian pets.

    Can birds recover from house finch eye disease?

    Yes, some house finches can recover from house finch eye disease, but many do not survive. Recovery is possible for some individual birds, but the disease can lead to blindness, making them vulnerable to starvation or predators. Even if a bird recovers, it may remain a carrier of the bacteria, and wild birds do not acquire full immunity to future infections.

    Why is the house finch particularly susceptible to this disease?

    It is unknown why house finches are more likely to contract conjunctivitis. The house finch, which is native species of the western United States, was introduced to the eastern United States in 1940 when a New York city pet store owner released illegally held finches to avoid prosecution. The pet owner was marketing them as “Hollywood finches”. The Hollywood tale is a success story for a glamour-labeled western finch who got a free ride due to the ambition of pet dealers who, when caught in illegal trade, turned the finches loose.…… and they would take over and become one of the most successful range expansions in US ornithological history. In only 50 years, House Finches colonized the eastern half of the U.S. to the point where the new eastern population meets the western population. Inbreeding and reduced genetic diversity resulting from the small number of individuals that started the eastern population, however, may make these finches less resistant to new diseases than other species.

    Can the closely related Purple Finches, and even Evening Grosbeaks and goldfinches get house finch eye disease?

    Yes, the very closely related purple finchescan get conjunctivitis, also known as "house finch eye disease" or Mycoplasmal conjunctivitis. The disease is caused by the bacterium Mycoplasma gallisepticum and has been reported in purple finches, American goldfinches, and evening grosbeaks. In one research trip to Maine by the Finch Research Network to tag and band evening grosbeaks in spring of 2022, as many as 25% of the birds had conjunctivitis -- The evening grosbeaks is in great decline, 90% since 1970, and is needs conservation efforts!

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