When migratory bird ecologist Brian Evans first started hearing about dead birds across Washington, D.C., in mid-May, he “wrote it off,” says Evans, who’s on staff at the Smithsonian Conservation Biology Institute's Migratory Bird Center. Bird deaths in the spring are common—only 30 percent of young songbirds typically survive to the next season. And with people stuck at home during the pandemic, “we’re noticing these things,” Evans says. “Everybody got into birds last year, and then this year they realize birds have awful lives!”
Then, while Evans was in his garden on May 28, his neighbor came over to tell him about a bird she had just found on the road. It looked like it was blind, she said, and it was shaking. When she walked up to it, it didn’t budge. “That’s when this little flash went off in my head saying, that’s pretty unusual,” Evans says. “That’s not your typical dying fledgling.”
Later that day, a colleague started texting him photos of dead birds. Half an hour after that, another neighbor called him to look at a bird that had crusty eyes and couldn’t balance. “I grabbed it and took it to City Wildlife,” he says, referring to a wildlife rehabilitation and release center in D.C. “I went in there, and they were like, Oh, yeah, this is really serious.”
The District of Columbia and at least 12 states on the East Coast, from Connecticut to Florida to Tennessee, are in the midst of a songbird epidemic. Thousands of young birds, including blue jays, common grackles, American robins, and European starlings, have suddenly gone blind, oozing from their eyes, shaking, and dying. Lab tests have ruled out some possible causes such as West Nile virus and avian influenza, leaving scientists struggling to come up with new hypotheses.
Though reported cases began to dwindle in D.C., Maryland, and Virginia by the end of June, new cases continue to be reported in other states. And as wildlife rehabilitation facilities have struggled to cope with the emotional toll of euthanizing suffering birds they can’t help, experts are racing to understand what might be going on.
What we know about the scale
“This event is remarkable,” ornithologist Evans says. “What makes it significant is the number of birds that have been ill or have died and the number of species that have been impacted.” Cases have also emerged in Carolina wrens, gray catbirds, cardinals, house finches, sparrows, and others. “One American crow was just standing in the street,” near his house in May, Evans says. “It was very unusual. It died as I was preparing to take it to City Wildlife.”
Also exceptional: The sheer spread of the disease cases, which have been seen in at least 12 states, and D.C. “It doesn’t look like we’ve seen anything at this scale in at least quite a while,” Evans says.
However, total and even statewide numbers remain tricky to determine, says Evans, who specializes in population ecology of migrating and resident birds. “I’m still desperately trying to understand the distribution” of the epidemic, he says.
Every state has its own system for data collection, and some are more robust than others, he says. Virginia, for example, has a public reporting system for anyone to record sick or dead birds they’ve observed, including symptoms, species, and location. So far, 1,400 cases have been submitted through that portal.
What we know about the cause—and what we don’t
On July 2, the U.S. Geological Survey, which is working with wildlife agencies in the affected states, announced that “no definitive cause(s) of illness or death have been determined at this time.” Testing of dead birds from multiple states has ruled out common bacteria such as salmonella and chlamydia, and viruses such as avian influenza, West Nile virus, various herpes viruses, and a host of others. There have been no reported cases of any transmission to humans, farmed birds, or other animals.
Mycoplasma, a bacteria, has been found in some samples, Evans says, “but that’s not necessarily unusual for birds, and it’s not typically associated with the neurological symptoms that are coming in.”
Determining the cause of any disease outbreak is often a slow process because it involves ruling out possibilities. This case is proving particularly challenging, he says, because “neurologic and eye symptoms are an unusual combination.” It could be a completely new pathogen, or it could be multiple factors working in tandem.
“Always, our first response to something like this is to look at what may have changed in the environment. What’s different this year from last year?” he says.
One obvious, ear-splitting answer: the billions of Brood X cicadas that blanketed the East Coast—a smorgasbord of food for every songbird within reach.
The curious cicada factor
In mid-May, when the bird deaths started, Evans and his colleagues were studying how cicada song might be influencing bird behavior. “As I’m thinking and talking to my colleagues, we’re all surrounded by the screaming of the cicadas. Of course it’s the cicada, [we’re thinking], we’ve got them on our arms right now!”
The fact that these insects emerge only every 17 years, that birds were gobbling them up, and then that many were suddenly getting mysteriously ill, was reason to give serious consideration to the possibility that there was a link, he says. “There’s about five different cicada hypotheses,” he says—the most prominent of which is linked to a fungus that affects about five percent of cicadas and produces a psychedelic toxin called cathinone.
It’s become increasingly clear in recent weeks, however, that the cicadas don’t seem to account for the bird deaths, he says. The geographic range of the bird epidemic is much larger than the range of the Brood X emergence, and it’s unlikely birds that were living in the cicada zone flew out of it. “They’ve set up their breeding grounds for the summer. They don’t typically move great distances at this point,” Evans says.
Smithsonian’s genetics lab and others are still working to rule out a cicada link definitively, but the timing of the bird deaths provides another clue that a link is unlikely. The Brood X cicadas died in mid- to late June, but birds are still falling sick. As recently as July 8, a male American robin was brought to Tamarack Wildlife Center in Saegertown, Pennsylvania, with head twitches and closed, crusted eyes. He was able to stand, briefly, before he died.
Caring for the dying
At City Wildlife, D.C.’s only wildlife rehabilitation organization, the onslaught of sick birds in mid-May was “heartbreaking,” says executive director Jim Monsma.
“Common grackles, European starlings, blue jays. All juveniles—fledglings, on the cusp of flying. One after another, they just started coming in, and then floodgates opened and there were just tons of these birds,” he says. “We heard about many more than we got because they would die before they got here.” Their eyes would go first, he says, swelling up and often looking bloody, and shortly after they would develop the neurological problems—spinning, falling on their backs and sides.
City Wildlife treated the first birds with antibiotics and pain medication, just as they typically do for birds with neurological symptoms. But this time, they quickly realized, “we lost them no matter what we did,” Monsma says.
“It was horrible. Horrible to watch. There’s nothing sadder than a blind bird. They know they’re in trouble and don’t understand altruism,” so anything a human does to help, he says, only scares them more. The reality, Monsma says, is that there was no way to help them.
“They were miserable and terrified and we just had to start euthanizing,” he says, which they do with a painless inhalant.
City Wildlife received 202 birds showing symptoms of the mystery illness between mid-May and June 23; a blue jay was received that day but since then, no other sick songbirds have been brought in. Recently, however, they’ve received six hawks displaying some similar symptoms. Five died; one seems to be recovering. Monsma says he is concerned that perhaps the hawks ate infected birds and got sick, but “it’s just conjecture.” The rehab organization team is awaiting test results.
Although cases are decreasing in some areas, it’s still vital to figure out the cause. If it’s a human-linked toxin, “we’d have to take action,” Evans says. If it’s an infectious disease, the public needs to know because bird feeders can play a significant role in spreading it.
“We don’t want to ask people not to feed birds,” he says—but at bird feeders, birds crowd together, all touching common surfaces. In normal times, his team recommends people clean their feeders regularly and rigorously, “but that’s not enough right now, in the middle of an outbreak.”
In the meantime, Monsma says he’s starting to see young, healthy blue jays and starlings—the species among the hardest hit by the illness—around D.C. again. Birds are resilient: “They can lose a whole family to disease, or cats, and start all over again. They just start laying eggs,” he says.
Yet at the same time, “it’s the individuals that suffer. That’s what we’re here for,” he says of City Wildlife and other rehab organizations. “To alleviate that. When you can’t, it’s really tough.”
HOW YOU CAN HELP:
The public has a vital role in helping stop the spread of the illness and determining its cause, Evans says.
Report: If you find a dead or sick bird, take photos, make note of its symptoms and location, and report it to the Smithsonian Migratory Bird Center’s online portal. Some states and regions also have ways to report, including Virginia, Pennsylvania, Delaware, and the Washington, D.C., region.
Rescue: If a bird appears to need medical attention, call your local wildlife rescue center for guidance (you can search by zip code in this database to find a wildlife rehab closest to you). Familiarize yourself with what to do if you find an injured or sick wild animal here. Avoid touching birds unless absolutely necessary. If you must, wear plastic gloves.
Reduce spread: If you have a bird feeder or bird bath in a region where cases have been documented, experts recommend that you remove it until the epidemic subsides. If you do keep your feeder up, clean it often using a solution of 10 percent bleach to 90 percent water.