Preventing Bird Disease

Preventing Bird Disease

UPDATED 8/16/21

Updates according to Cornell Wildlife Health Lab

The Cornell Wildlife Health Lab has been monitoring the evolving situation. The lab, housed under the Cornell University College of Veterinary Medicine, was created in 2010 with the Department of Environmental Conservation in order to develop a wildlife disease surveillance program. The lab works with a network of partners on the local, state, and national level, and engages with the public in order to promote the health of wildlife populations.

Through their highly connected communication channels, the lab received the first reports of cases at the end of May from partners in Maryland, Pennsylvania, and Washington, DC. Researchers in these states began testing, but were unable to come up with any conclusive results about the outbreak.

“Over the course of weeks, no one was finding anything infectious,” Elizabeth Bunting, Senior Extension Associate at the Cornell Wildlife Health Lab said. “They did a lot of testing but could not come up with any disease process, and the rehabilitators were telling us they were trying antibiotics and things like that, but they did not have great effectiveness.”

Bunting said that the outbreak exhibits similar symptoms to mycoplasma, a bacterial infection that commonly afflicts finches, causing swollen eyes. However, this disease lacks the neurological components that accompany the unknown illness. Labs across the nation have ​​worked to rule out many other possibilities including salmonella, avian influenza, and the West Nile virus.

In just the past few weeks, the Wildlife Lab has received widespread news of declining cases and dropping mortality rates.

“Information coming out of the National Wildlife Health Center and some of the other states said that the cases were declining all of a sudden,” Bunton said. “That would not be typical of an infectious disease outbreak. You wouldn’t expect an infectious disease to just spontaneously go away.”

This sudden decline lends support to the tentative hypothesis regarding a cause of the outbreak. The most recent working theory is that the outbreak is related to the emergence of the cicadas this year — the geographic distribution and the timing of the undetermined songbird illness directly coincides with the arrival of the cicadas.

The cicadas emerged in Washington, DC and eleven other states: Delaware, Indiana, Ohio, Pennsylvania, New Jersey, Maryland, West Virginia, Virginia, Tennessee, Florida, and Kentucky in mid May. Birds in these states started showing the unusual symptoms about a week later.

“The distribution of states where this spontaneously popped up was an exact match for the cicada emergence map, and it is a very strange distribution of states for this kind of outbreak,” Bunton said. “It was Virginia, West Virginia, Maryland, Delaware, New Jersey, Pennsylvania, and then it moved over to Tennessee, Kentucky, Ohio, Indiana but it completely skipped New York and the rest of New England. That is an exact replica of the cicada map.”

Researchers such as Bunton believe that the ingestion of the cicadas could have had toxic effects on the birds. It is possible that individuals sprayed the cicadas with pesticides, which have chemicals that affect the brains of birds and could have caused the neurological symptoms. Cicadas also carry fungi that can produce toxins when ingested which could have also produced the illness in the birds.

The decline in cases corresponds with the retreat of the cicadas. Although researchers will continue to monitor the situation, Bunton expressed that the outbreak should not be a cause of alarm. The diminishing outbreak does not pose any safety threats to humans, nor does it threaten the stability of the various songbird species.

“This seems not to have been something that was going to travel and have a really significant impact,” Bunton said. “But we are very thankful that people are paying attention. This is exactly what we need to have happen when we see things in wildlife that are concerning.”


Many of you have called with questions about the bird disease in the Mid Atlantic states. Here is what we recommend:
There is an unknown disease that has been causing bird deaths in parts of the Mid-Atlantic and Southeastern United States over the past two months.
The symptoms include eye swelling with crusty discharge, as well as neurological issues like appearing disoriented.

There are studies in progress to determine the cause of the disease, and many things have been ruled out.  There is a theory that there is a connection between the disease and the arrival of this year’s Brood X cicadas.  Another theory is that it is similar to the finch eye disease, which is a form of conjunctivitis.
When birds congregate in one place, it increases their chances of spreading disease, and a lot more people are feeding the birds these days.

That said, it’s important err on the side of caution for our beautiful feathered friends. We are asking that everyone be diligent in cleaning their feeders and birdbaths with a 1/10 percent bleach solution to kill lingering pathogens. (1 part bleach 9 parts water, use clorox bleach – bargain brands are not as effective)

Keep the feeders and baths clean on a regular basis and keep our feathered beauties safe.
Thank you!

While there is always an increase in reports of dead birds at this time of year due to natural high mortality rates of young birds, MassWildlife is encouraging the public to report any observations of sick or dead birds (with unknown cause of mortality) as a precaution to help track this widespread mortality event. However, the mystery disease is not known to be in any of the New England states at this time. It is not necessary to report dead birds where strong evidence links the mortality to collision with glass or vehicles or predation by cats. Please email reports to and include your location, number and species of birds, symptoms observed, and any photos.