How to Deal With House Finch Eye Disease

Wednesday, January 15, 2020
Blech. Cold & flu season is upon us and many of us are feeling the effects of one bug or another. Unfortunately, the same is true for our feathered friends. While illness and disease can occur at any point throughout the year, birds are often at higher risk during the winter months because of their flocking habits which brings large groups of birds together in small areas - like our feeding stations. One disease that can be seen in some of Ontario's bird populations is Mycoplasmal conjunctivitis, otherwise known as House Finch eye disease. This highly contagious disease can move through flocks of finches in a hurry, so it is important to recognize the signs in order to act quickly to help keep birds safe & healthy.

A healthy House Finch (Haemorhous mexicanus) perched on an APS Branch Perch Arm

What is House Finch Eye Disease?
House Finch eye disease (or Mycoplasmal conjunctivitis), is a highly contagious respiratory disease that affects some wild & domestic birds. The disease was first detected by backyard birdwatchers in Maryland in February 1994, when birds with crusty, swollen eyes were showing up at their feeders. These keen birdwatchers submitted their findings 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 eastern North America, as far north as Quebec, as far south as Florida, and as far west as California. Click here for more information on House Finch eye disease studies.

House Finch (Haemorhous mexicanus) infected with House Finch eye disease
What does it look like?
Birds infected with House Finch eye disease will often have runny, crusty, swollen, or red eyes, and in severe cases (like the bird in the photo above) 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 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) is Avian Pox; in the case of either of these illnesses it is best to follow the protocol below to prevent infecting other birds.

American Goldfinch (Spinus tristis) infected with House Finch eye disease

Does it only affect House Finches?

The name would make you think so, wouldn't it? Not in this case. 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. Other species may also be carriers of this highly contagious disease, but not show any outward signs of illness.

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 (red, crusty, swollen eyes, etc), it is important to immediately remove your feeders & dispose of all uneaten seed - this includes feeders that you did not see the bird feeding from. The next step is to clean & disinfect all feeders; to do this you will need to thoroughly clean your feeders with a brush to remove any visible dirt or mold. Once you are finished intial cleaning, submerge the feeders in a 10% bleach solution for a minimum of 10 minutes, this acts as a disinfectant and also helps to loosen any grime build-up; scrub feeders again with brush & rinse thoroughly for at least 15 seconds in warm water. Be sure to clean the areas around your feeding stations as well, by raking and disposing of any seed on the ground. For full cleaning instructions, click here. Now for the hard part.. 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 neighbours who you know feed birds, it would be a good idea to let them know about the sick birds in the area so they can be more cautious with their cleaning regime as well.

A clean and tidy WBU feeding station with lots of bird activity
How can I help avoid spreading disease in my yard?
There is no guaranteed way to avoid the spread of House Finch eye disease or any other illness that may arise in your backyard birds, but there are a few simple and effective actions to 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. Cleaning your feeders & surrounding area (the ground included!) once every two weeks (once per month at the very minimum) through the winter months can help minimize the growth of harmful bacteria and spread of disease & parasites. Bird bath water should be changed daily, and baths cleaned regularly. To learn how to properly clean & disinfect your bird feeders, see our blog How to Clean Your Bird Feeders.
  2. Monitor your backyard birds closely: This is beyond having a quick peek 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 - will help you see them more clearly, and give you a better idea of what is normal appearance & behaviour 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 Project FeederWatch: Participating in citizen science projects like Project FeederWatch, and submitting sightings of birds with symptoms of illness, can help scientists and conservationists better understand how disease is spread & where it's spreading to. So while it may not have an immediate effect on the birds in your yard, long-term research on disease in wild birds may one day provide new methods of controlling the spread of these diseases. 

For more in-depth information on House Finch eye disease, visit Project FeederWatch.

Now that you know what it is, what it looks like, who can contract it, how to disinfect your feeding station, and how to prevent it in your yard, you can keep an eye out for birds who exhibit symptoms of House Finch eye disease and act quickly to help keep our bird populations safe & healthy.

Happy trails!
- Shayna

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