Frequently Asked Questions

Seen a sick bird and want to report it?

Unfortunately, we no longer have a system for collecting information on diseased birds from anyone who wants to report their observations. The House Finch Disease Survey has been stopped because we have been unable to obtain the funding to manage this citizen-science project. Participants in Project FeederWatch, a winter-long count of birds at bird feeders, optionally can provide their observations of diseased House Finches. Please consider joining Project FeederWatch, to tell us not just about diseased birds but about all of the birds visiting your feeders in winter. For a limited time starting in mid-2009, existing participants in the House Finch Disease Survey can continue submitting observations until the supply of data-collection forms is exhausted.

What does conjunctivitis look like?

Infected birds have red, swollen, runny, or crusty eyes; in extreme cases the eyes become swollen shut or crusted over, and the birds become essentially blind.  Birds in this condition obviously have trouble feeding.  You might see them staying on the ground, under the feeder, trying to find seeds.  If the infected bird dies, it is usually not from the conjunctivitis itself, but rather from starvation, exposure, or predation as a result of not being able to see.MORE PHOTOS

Photo by Lab member Nicole Kennedy

Do other diseases cause similar clinical signs?

Avian pox is another common disease that affects a bird’s eyes. This disease causes warty lesions on the head, legs, and feet, but cannot always be easily distinguished from conjunctivitis. Avian pox is transmitted by biting insects, by direct contact with infected birds or contaminated surfaces (e.g. feeders), or by ingestion of contaminated food or water. Just as with conjunctivitis, the infected bird becomes vulnerable to predation, starvation, or exposure.  MORE PHOTOS Avian pox
An example of avian pox.
Photo by the New York State Department of Environmental Conservation.

What causes the conjunctivitis?

Although infected birds have swollen eyes, the disease is primarily a respiratory infection. It is caused by a unique strain of the bacterium Mycoplasma gallisepticum, which is a common pathogen in domestic turkeys and chickens. The infection poses no known health threat to humans, and had not been reported in songbirds prior to this outbreak. Researchers at various institutions are currently trying to learn more about the transmission, genetics, and development of this disease.


Where did the disease start?  How far has it spread?

Conjunctivitis was first noticed in House Finches during the winter of 1993-94 in Virginia and Maryland. The disease later spread to states along the East Coast, and has now been reported throughout most of eastern North America, as far north as Quebec, Canada, and as far south as Florida. It has also appeared in some species other than House Finches. Your participation in this survey will help document further changes of this epidemic. View map showing the prevalence of the disease since it was first observed.

What other bird species have been diagnosed with mycoplasmal conjunctivitis?

So far, the disease is most prominent in the eastern population of House Finches. However, a few reports of the disease have been confirmed in American Goldfinches, Purple Finches, Evening Grosbeaks, and Pine Grosbeaks, all members of the family Fringillidae.


Why might eastern House Finches have been the earliest victims of the disease?

House Finches are not native to eastern North America. Until the 1940s, House Finches were found only in western North America. Some birds were released to the wild in the East after pet stores stopped illegal sales of "Hollywood Finches," as they were commonly known to the pet bird trade. The released birds successfully bred in the wild and spread rapidly throughout eastern North America. Because today’s eastern House Finch populations originated entirely from a small number of released birds, they are highly inbred, exhibit low genetic diversity and, may therefore be more susceptible to disease than other bird species native to the East.


Why has the disease spread so rapidly among House Finches?

The House Finch population is large, and the birds tend to move together in highly mobile foraging flocks. Therefore, diseased individuals are constantly entering new areas, increasing the chance of infecting other birds in that area. Also, some infected birds do not die from the disease, which increases the probability of its transmission to other individuals. Lastly, current evidence suggests that infected birds do not acquire immunity to future infections.


Do bird feeders encourage the spread of conjunctivitis?

Whenever birds are concentrated in a small area, the risk of a disease spreading within that population increases. Even so, feeding birds may not necessarily increase the rate of disease spread, and should not have a net negative impact on the House Finch population. House Finch Disease Survey data tell us that the disease has decreased from epidemic proportions and is now restricted to a smaller percentage of the population. We estimate that 5% to 10% of the eastern House Finch population has this disease and that the dramatic spread that occurred a few years ago has equilibrated. This means that it is still an important and harmful disease, but that House Finch populations are not currently at extreme risk of wide-spread population declines. 

Your continued participation in the House Finch Disease Survey will allow researchers to better understand the risk factors for conjunctivitis. In the meantime, please be responsible and clean your feeders on a regular basis even when there are no signs of disease. Follow the above recommended guidelines as you feed birds.


What should I do if I see a bird with conjunctivitis?

Take down your feeders and clean them with a 10% bleach solution (1 part bleach and 9 parts water). Let them dry completely and then re-hang them. Also, rake underneath the feeder to remove old seed and bird droppings.

Should I try to treat an infected bird?

By law, only licensed professionals are authorized to handle most wild birds. Although it is possible to treat finches with conjunctivitis, you should not add medications to bird seed or baths under any circumstances. There is no way to know if medication actually helps birds in uncontrolled conditions, and such treatment may in fact contribute to disease spread by allowing infected birds to survive longer. Treatment with antibiotics may also lead to the rapid evolution of novel strains of the disease that could possibly spread to other songbirds.


Bird-Feeding Guidelines:

  1. Space your feeders widely to discourage crowding.
  2. Clean your feeders on a regular basis with a 10% bleach solution (1 part bleach and 9 parts water) and be sure to remove any build-ups of dirt around the food openings. Allow your feeders to dry completely before rehanging them.
  3. Rake the area underneath your feeder to remove droppings and old, moldy seed.<
  4. If you see one or two diseased birds, take your feeder down immediately and clean it with a 10% bleach solution.

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