2021 Mystery Bird Illness – A Must-Read Update

One of the most frustrating issues for me during this bird illness crisis has been waiting for news on what is causing this disease and when it will be safe to return to bird feeding. An excellent article from Scientific American published on August 13 may help shed some light on the situation with an added caution – it may still be too early for us to hang up our bird feeders just yet.

In May 2021, a mysterious illness impacting primarily young fledgling birds appeared in Washington, D.C., and surrounding states. By June, ten states reported birds with symptoms that included crusty and swollen eyes, blindness, lethargy, inability to stand, and tremors. Alerts from rehabilitation centers and state wildlife agencies advised residents in impacted areas to remove their feeders and birdbaths. At the same time, experts scrambled to find the cause of the mass casualty event. 

But with reports of dead and sick birds waning by the end of July, some experts recommended it could be safe to return to feeding in areas where sick and dying birds were no longer present.

To Feed or Not to Feed

In August, the Indiana Department of Natural Resources announced that 76 counties could return to bird feeding. A portion of the state is still part of the no-feed ban.

With decreasing reports of sick and dead birds, the Pennsylvania Game Commission opted to lift their statewide bird feeding ban.

In New Jersey, the Office of Fish and Wildlife Health and Forensics still encourages residents encountering sick or dead birds to keep their bird feeders and bird baths down for the time being.

In Massachusetts and Rhode Island, states where very few if any reports of the illness were identified, the ban on bird feeding remains in place. Connecticut joined the list recommending birders take down their feeders when reports of the disease hit their state in July.

Cornell Wildlife Health Lab “Not Overly Alarmed”

In an article posted on, researchers at the Cornell Wildlife Health Lab remained “vigilant about the situation and researching causes.” Still, they were “not overly alarmed, especially as cases taper off and songbird populations remain stable.”

A researcher at Cornell pointed to the cicada emergence as a potential cause of the disease outbreak, though that conclusion is under intense scrutiny by other scientists.

Quoting the article, The National Wildlife Federation released an upbeat video announcing it “should be ok to put bird feeders and baths out.”

Days later, they provided an update and clarification, noting their advice “could be premature.”

A Scientist’s Discovery

The Scientific American article is likely one of the best pieces I’ve read on the issues to date – and provides solid scientific-based advice to guide backyard birders.

Author Maddie Bender provides an in-depth interview with Brian Evans, a quantitative ecologist at the Smithsonian Conservation Biology Institute’s Migratory Bird Center (SMBC) in Washington, D.C. He discusses the early days when the disease began to emerge, the role of citizen scientists in reporting their findings, the lengths researchers are taking to solve the mystery, and what the public can do while we wait for answers.

With reports of sick birds from his neighbors in Maryland in May, Evans’ initial perspective on the emerging illness quickly changed. After a visit to City Wildlife, a D.C. area wildlife rehabilitator, he realized something serious was going on.

What I Learned

The takeaways from this piece are numerous.

First, our role as citizen scientists in the bird community is essential.

Being aware of what is going on in your eco-systems, no matter how small, can provide an early warning response to experts when you see something that doesn’t seem right.

By observing, recording, and reporting issues to your local wildlife rehabilitators or state wildlife agencies, you can be a part of helping keep our backyard birding populations safe and healthy.

Second, good science takes time.

While I knew that researchers were investigating the potential causes of this mystery outbreak, I didn’t realize the depth of what they had to do to reach scientifically sound results. It takes time. Plain and simple.

After ruling out common diseases with similar symptoms, in-depth testing is underway to dig deeper for answers. That means more complex testing, reaching out across the nation to learn from other impacted areas, establishing disease control groups, and more.

And finally, be patient and listen to the experts.

Everybody’s champing at the bit to put their bird feeders back up. I’ve heard so much language and so much pressure—“When can I start feeding birds again?” And my answer is always “Let’s wait and see what [the U.S. Geological Survey’s National Wildlife Health Center] says.” If it’s an infectious disease, and we care about birds, we shouldn’t be putting our feeders back.

Brian Evans, Smithsonian National Zoo and Conservation Biology Institute in Washington, D.C.

Know your wild bird rehabilitators and your state wildlife agencies. Regularly log on to their websites and keep abreast of the situations impacting the wildlife in your community. If experts recommend you take down your feeders and birdbaths, heed their warnings until you know it is safe to return to feeding again.

If you’re able, support animal rehabilitators by donating money, needed supplies or your time to their facilities.

I’ll keep repeating myself on this topic, too: maintaining your bird feeding and birdbath areas should be a regular part of your responsible backyard birding habits. Cleaning your feeders the right way, removing fallen seed debris, using the right foods for your birds, and maintaining water sources are essential practices for common disease control.

Looking Ahead

The bright spot in this article is that Evans believes they eventually will have answers to this mystery illness. “I think it’ll be solved. To me, the biggest thing to solve first is whether it’s caused by an infectious disease or whether it’s caused by a toxin,” he says.

The most important thing we can do as responsible backyard birders?

“The most important thing that folks can do is just submit their observations. I’ve gotten reports from people, both through the bird mortality reporting form…bird enthusiasts should submit their observations and take a lot of pictures and videos of birds,” he adds.

Mystery Bird Illness Resources

-Watch The Connecticut Audubon Society’s 8/14/21 presentation “Dying Birds – What We Know & What We Don’t Know” (Brian Evans from the Scientific American article is interviewed)

-To review the most recent recommendations in impacted “mystery illness” regions including reporting portals review our state specific alert guide

-Find help for sick birds with our state specific wildlife rehabilitator list

-Help spread the word about the mystery bird illness with our fact sheet What You Should Know About Wild Bird Illness ’21

-Watch our YouTube video on the Mystery Bird Illness

Donate to City Wildlife, an animal rescue and rehabilitation center on the front lines of this mystery illness.

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Lindy is a proud member of the following organizations dedicated to protecting wild birds