House Finch Eye Disease AKA Mycoplasmal (Avian) Conjunctivitis

We generally do not hear too much about House Finch Eye Disease in our area, due in large part to our dry climate, but it is still one of the most commonly seen (and discussed) illnesses in feeder birds. We have not heard reports of populations with House Finch Eye Disease among our customers since early October of 2022.

In our area especially, House Finch Eye Disease is much more likely as the weather gets colder and birds start to flock together more and more for winter survival. While illness and disease can occur at any point throughout the year, that flocking behavior puts our feathered friends at higher risk. One relatively common disease that often starts showing up in the fall and winter months is Mycoplasmal Conjunctivitis, otherwise known as House Finch eye disease. Much like a cold at a school, this highly contagious disease can spread quickly through flocks of finches, so it is important to recognize the signs in order to help keep your backyard birds safe & healthy.

What is Mycoplasmal Conjunctivitis?
House Finch eye disease (or Mycoplasmal conjunctivitis), is a highly contagious respiratory disease that affects some wild & domestic birds. Although infected birds often have swollen eyes, the disease is primarily a respiratory infection. The disease was first detected on the East coast in 1994 when birds with crusty, swollen eyes began showing up at their feeders. These sightings were reported to Project FeederWatch, and soon after the volunteers and researchers from Cornell Lab of Ornithology noticed a pattern of sick birds in the Washington area. Lab tests were conducted and revealed the sick House Finches that were being reported were infected with Mycoplasmal Conjunctivitis, a respiratory disease previously known to only affect poultry such as turkeys or chickens. Since 1994, House Finch eye disease has been reported in most of North America, as far north as Quebec, as far south as Florida, and as far west as California. The infection poses no known health threat to humans and had not been reported in songbirds prior to this outbreak. House Finch eye disease has been found in a number of species from the Fringillidae (finch) family including American Goldfinch, Purple Finch, Evening Grosbeak, and Pine Grosbeak.

What does it look like?
Birds infected with Mycoplasmal Conjunctivitis will often have runny, crusty, swollen, or red eyes, and in severe cases the eyes can become swollen shut or crusted over, leaving the bird blind. These symptoms can also cause an infected bird to have trouble eating, and they will typically spend more time than usual at feeders or on the ground trying to find seeds. These symptoms, rather than the disease itself, are often what lead to a bird's death by way of starvation or predation. Another avian disease that presents itself with similar symptoms (though affects a wider range of species and causes warty lesions on the head, legs, and feet) is Avian Pox; in the case of either of these illnesses, it is best to follow the protocol below to prevent infecting other birds.

What do I do if I suspect a sick bird at my feeders?
If you've noticed a bird who has any of the aforementioned symptoms it is important to immediately remove your feeders & dispose of all uneaten seed - this includes feeders that you did not see the sick bird feeding from. The next step is to clean and sanitize all feeders; to do this you will need to thoroughly clean your feeders with a brush to remove any stuck seeds, visible dirt, or mold. Once you are finished with the initial cleaning, wash your feeders in a 10% bleach solution (one part bleach to nine parts water), then thoroughly rinse, and let feeders dry completely before using them again.  Be sure to clean the areas around your feeding stations as well, including any hardware and raking and disposing of any seed on the ground. Feeders should remain down for at least two weeks to deter sick birds from returning to your yard. As painful as it is for us to lose our feathered friends for a short period, this step is imperative to help limit the spread of disease to other birds in your area. If you notice a sick bird after the waiting period, repeat these steps. If you have neighbors who you know feed birds let them know about the sick birds in the area so they can be more cautious with their feeding and diligent in their cleaning as well.


How can I help avoid spreading disease in my yard?
There is no guaranteed way to avoid the spread of illness in your backyard birds, but there are a few simple actions you can take to help lessen the risk of it spreading through your feeders and yard.

  1. Maintain clean feeding stations & bird baths:  This is the #1 thing you can do to help slow the spread of disease. It’s always a good idea to practice responsible bird feeding. Regularly Clean and sanitize all bird feeders, bird baths, and hardware. If you see or suspect a sick bird we recommend a 10% bleach solution (one-part bleach to nine parts water). For normal cleaning, a solution of half white vinegar and half water is a great natural option. Rinse thoroughly and allow to completely dry before refilling feeders and baths. Cleaning the area around your bird feeders (the ground included!) can also ensure that no disease or mold and mildew issues are lurking in discarded seeds or shells. Bird bath water should be changed daily, and baths cleaned regularly. 
  2. Monitor your backyard birds closely:  We mean more than having a look to see if there are birds at your feeders or not. Watching the birds in your yard closely - with binoculars, scope, or zoom lens on a camera if you like - will give you an idea of what is normal in appearance & behavior of a healthy bird vs a sick bird. Using a camera will also allow you to document any abnormalities you may see, such as crusty or swollen eyes, and use the photos to help identify specific illnesses.
  3. Participate in Citizen Science Projects:  Citizen Science like Project FeederWatch can help scientists and conservationists better understand how disease is spread & where it's occurring. So while it may not have an immediate effect on the birds in your yard, long-term research on diseases in wild birds may one day provide new methods of controlling the spread.