Collin Buenerkemper/CNET

The mysterious case of America's dying songbirds

Common birds, like the blue jay, are turning up sick or dead across the eastern US. What's killing them?


One day in late May, a stranger contacted Erica Miller about a sick bird. For a volunteer wildlife rehabilitator, that isn't unusual. She's rescued 1,794 animals so far this year, many of them birds, and mostly thanks to tips from people who come across sick or injured animals. This was different. 

"So I got a call, and it was [about] an adult blue jay. I don't get adult blue jays in here. They're very hardy birds; they're very mean, honestly, but you don't have to worry about them," Miller explains. 

Minutes later, she got another call about a sick blue jay. Miller assumed the call was from the same family, maybe a husband and wife who both mistakenly got in touch about the same bird. Instead, two people showed up at her 60-acre property outside Dayton, Ohio, each with a sick blue jay. Blue jays are vibrant, chatty birds best known for their bright blue color and for being extremely territorial. Both of these birds had swollen eyes and were weak to the point of starving. 

"I looked at [the birds] and I was like, 'Oh, this is weird,'" Miller remembers. Four days later she had seven sick blue jays. Despite her best efforts, all of them died within a day or two. In her eight years as a wildlife rehabilitator, she had never seen anything like this.

Around the same time, similar reports of sick or dying blue jays, grackles, starlings, robins and other common songbirds were popping up across the eastern US. Like Miller's birds, they had crusty, puffy eyes. Many acted confused and showed signs of neurological issues. By June, wildlife agencies would report hundreds of instances of illness across Washington, DC, and 10 states, including Virginia, West Virginia, Maryland, Kentucky, Pennsylvania, New Jersey, Delaware, Indiana, Ohio and Florida. 

Birds were already in trouble before the mysterious illness appeared. The overall bird population in North America has declined by 30% since 1970, largely due to habitat loss. Two-thirds of birds in North America today face a greater threat of extinction as global temperatures increase as a result of human-generated carbon emissions. Despite overall population declines, some birds -- like the bald eagle -- are growing in number due to conservation efforts. 

Birds play important roles in a balanced ecosystem, pollinating the crops we rely on for survival and regulating insect and other animal populations. Birds are also our early warning systems, letting us know when something is off. 

"The 'canary in the coal mine' metaphor is there for a reason," explains Nat Miller, director of conservation for the Great Lakes and Upper Mississippi Flyway. "Birds are often an indicator that things are good or bad in our environment, and where we see healthy populations of birds, people also are doing well." 

That's why scientists are concerned about this new, unknown illness. So far, there's no indication it can spread beyond birds or that it's necessarily contagious at all, but scientists have urged individuals with bird feeders to remove them and clean them carefully just in case. 

To stop the illness, they need to know what it is and what's causing it -- but they're still completely in the dark. "I think the issue now is we don't have something that's consistent that we've seen across the board in terms of a pathogen that's present," says Christine Casey, state wildlife veterinarian for the Kentucky Department of Fish and Wildlife Resources. 

She's asking people to be patient while scientists continue to investigate, but she isn't hopeful. "We haven't really been successful in eradicating any wildlife diseases. In the grand scheme of things, we're not good at eradicating diseases," Casey adds. 

Hollow bones

The ancestors of modern birds are 65 million years old, but birds also share evolutionary history with dinosaurs. Archaeopteryx, a small, feathered dinosaur with teeth, is widely considered the "first bird." Archaeopteryx was awkwardly flying around 150 million years ago, during the late Jurassic period, the same time the slow-moving, spike-spined Stegosaurus was alive. 

Today, there are 50 billion birds living on all seven continents. They don't all fly, but they all have wings, feathers, a unique respiratory system with air sacs in addition to lungs -- and hollow bones. (I'll never read "hollow bones" again without hearing Emily Mortimer's 30 Rock character Phoebe saying, "I have hollow bones, like a bird."

All of those characteristics make it possible for birds to fly, but they do much more than that. Feathers and wings repel water and insulate birds against changing weather conditions, and their respiratory system regulates their body temperature. Birds are unusually well equipped to travel to and survive in many different climates and environments, but habitat loss and the climate crisis are making life harder for them. 


A healthy adult robin eats berries.

Ohio Division of Wildlife

More than 75% of adult birds die during migration, says Nat Miller. "Most birds in North America migrate twice a year, some of them very long distances, and that timing is based on evolution." Miller notes that over eons, birds have learned to migrate just as certain seeds become available or insects are hatching. As habitats are removed or destroyed, it throws the timing off and puts the birds in danger. 

Scientists are also seeing an uptick in wildlife illnesses, which Laura Kearns, a wildlife biologist with the Division of Wildlife at the Ohio Department of Natural Resources, says could be related to climate change. 

"It just seems like there are more and more of these novel wildlife diseases popping up among different taxa, not just birds, and it's a little scary," she says. "A lot of concerns with climate change as the planet warms up, it incubates or fosters novel diseases coming along." It shifts where animals go and how they interact with the environment, which can mean carrying diseases to new locations.

Novel, or new, wildlife illnesses used to occur about once a decade, but "that statistic might be changing," Kearns explains. 

She remembers when West Nile virus, a disease primarily transmitted to birds by mosquitoes, first appeared in the US in 1999. Kearns calls the initial outbreak of West Nile virus "comparable" to what we're seeing with this new illness. "[It was a] similar situation [with] birds coming in. You couldn't do anything to treat them. And you look at those long-term monitoring datasets for those particular species and you can see a drop." Over 20 years later, West Nile virus is still here. 

In 2015, highly pathogenic avian influenza, or bird flu, was found in the US, infecting both wild birds and domestic poultry. More than 60 million chickens had to be killed to get it under control, which cost more than $3 billion, says Bryan Richards, wildlife biologist and emerging disease coordinator with the US Geological Survey's National Wildlife Health Center. 

In addition to the ecological costs of losing hundreds of songbirds, the broader threat of an illness potentially spreading to domestic poultry -- and the resulting economic loss -- are reasons enough to track and understand this new bird illness, Richards says. "There's always a chance with some pathogens that it could spill over into domestic livestock or into companion animals."

'The bird ick'

Scientists are still in the early stages of identifying the illness killing blue jays and other birds. "I've just been calling it 'the bird ick,' which is not scientific at all," says Stormy Gibson, interim executive director at the Ohio Wildlife Center. Gibson and her team of wildlife rehabilitators have seen a lot of reports of the illness. At one point in the summer, they were getting "at least" 50 to 60 calls each day from people who saw a sick or dead bird, or had questions about what to do with their bird feeders.

Like Erica Miller, the volunteer wildlife rehabber who got the call about the two sick blue jays, the Ohio Wildlife Center takes in a variety of sick and injured animals every year. Rabbits are the most common; birds are second, Gibson says. She sends some of the animals to diagnostics labs for further testing, most recently the sick birds.

They're sent in biohazard boxes, Gibson explains. "When I'm handing it over to the UPS person, he says, 'What's going on?' I said, 'Well, there's been a lot of deaths in birds, and we're not sure what happened.' And he said, 'Well, I hope it's not COVID.'"

COVID-19 has helped people understand the risks of disease mutations, Gibson says. "So when he made the off joke of, 'I hope it's not bird COVID,' in the back of my mind I said, 'I really hope it's not bird COVID.'"


Bird ick.

Stormy Gibson

A bunch of known pathogens have been ruled out, including COVID-19, West Nile virus and bird flu, among other common illnesses and diseases. But figuring out what it isn't is much easier than identifying what it is.

"There's a complexity to disease and disease ecology that people don't understand," says Casey, the Kentucky Fish and Wildlife veterinarian.

Diagnostics labs can run polymerase chain reaction (PCR) tests, which is the same process used to identify COVID-19, HIV and other diseases in humans, but only for the pathogens they already know about. "But if it's something new, if it's a new species that we haven't discovered before, or if it's a species that we know about, but we've never seen in birds before, we're not gonna know to look for it," Casey says.

Casey doesn't think it's a parasite or a fungus because they're easier to see with a regular microscope. Bacteria are smaller and more difficult to see, so the researchers are upgrading their tech. Currently, they're waiting for an electron microscope, which will allow them to see more than they can with the standard equipment. 

They're working hard to identify what's killing these birds, but the speed of testing and the access to high-tech equipment comes down to money. "Science doesn't work [quickly], I mean, unless you have a lot of money, which, believe me, wildlife does not have a lot of money," Casey says.

Common birds

The birds affected by this illness so far have been "regular" birds, the kind you see all the time in your backyard, on your street and in your town. Because they're plentiful, there isn't immediate concern that entire songbird species are under threat of being wiped out, says Nat Miller, the Great Lakes and Upper Mississippi Flyway director of conservation. New cases of the mysterious illness have slowed to a trickle since the end of July, too, which is good news. But there are concerns about it recurring and what that could mean for bird populations long term. 

There's a mantra in bird conservation: "Keeping common birds common," Kearns says. "So when something new, like this disease outbreak, comes to the forefront, there's a lot of concern." The passenger pigeon, which used to number in the millions, was a common bird that went extinct in 1914. "That could still happen today," she adds. 


Grackles are a type of blackbird prevalent in North America.

Ohio Division of Wildlife

For now, scientists are still trying to figure out what's causing these birds to get sick. One theory linked the emergence of the Brood X cicadas to the illness in birds. The timing lined up, but birds in states without Brood X cicadas also saw instances of the illness. Other areas with lots of cicadas didn't see sick birds at all. 

Stormy Gibson, the wildlife rehabber and interim executive director at the Ohio Wildlife Center, is concerned that the illness will recur as soon as this fall, when birds north of the affected regions start migrating south and coming into contact with birds in other states. 

"Once [a new disease is] introduced, then I have to deal with early detection, containing and managing. Anytime a disease gets into wild animals, and it becomes endemic, it is almost impossible to eradicate," says Casey, the veterinarian with Kentucky Fish and Wildlife.

Everyone researching this is frustrated. For Casey, it's a combination of wildlife departments not having enough money, testing taking a long time and a lack of important baseline data to understand what "normal" amounts of toxins are in birds. "Try and guess how much research has been done about the normal levels of pesticides in birds. Zero. So we don't know how to interpret [the test results]," she says.

Bird enthusiasts are frustrated too; they want to put their bird feeders back out as soon as possible. Some states, including Kentucky, Pennsylvania and Maryland, have given official go-aheads to return feeders outside. Ohio and others are still suggesting people hold off. 

"I know a lot of people wanted an answer really quickly, but unfortunately, especially with new pathogens, whether it's a new pathogen or a new disease, the issue is disease can be a multifactorial issue," Casey says. "It may not be just one pathogen present."

Mad science

For Erica Miller, the wildlife rehabilitator, her drive to save these birds goes deeper. The same week her husband was diagnosed with stage four cancer eight years ago, they found an orphaned raccoon and took it in. It became part of the family -- swimming with them in their pond, roaming freely around their house and napping with her husband after his cancer treatments. 

"It was something that was really, really good during a really bad time," she says. Her husband survived and she decided to "pay it forward" by becoming a licensed wildlife rehabilitator. 

Miller is the only person I spoke with who has managed to save any of these sick birds. "I think most people did give up, you know, they were just taking them in and not really doing treatments because it's a waste of your medicine," she explains. "We don't get paid for this, so all the treatment you're using, it's on your dime. Those are medications that you have to buy so you just don't want to keep dumping your money into something that's not going to live."


A fledgling blue jay perches on a branch.

Ohio Division of Wildlife

While the authorities attempt to find what's causing the mystery illness, Miller has taken treatment into her own hands. "I kind of made a mad scientist chart and wrote down which species of bird it was, what treatment I did for it and what happened to it," she says. As a former ICU nurse, Miller is dogged and systematic in her approach. She says she's willing to try anything -- different methods and different treatments -- as long as she's not doing harm to the animal.

Eventually, using a combination of an antibiotic called enrofloxacin -- "It's one that I use when nothing else works" -- and the topical ointment Neo-Poly-Bac for the eye inflammation, Miller had some success. She was able to release 11 fledgling starlings and robins previously suffering from the illness back into the wild. 

She reported her findings to the Division of Wildlife, including what worked and what didn't. Kearns, the wildlife biologist with the Division of Wildlife, forwarded Miller's data to the USGS National Wildlife Health Center. "Unfortunately, I'm not sure what level of success others have had with these treatments, or really what they have tried," Kearns says.

Miller also shared her results with other wildlife rehabilitators and knows of at least one other rehabber who was able to release some songbirds using the same combination of medicine. 

While it may not yet have a name, Miller's efforts have shown that the bird ick isn't a death sentence. Even as scientists race to understand the underlying cause, the illness can be treated. 

And so the songbirds sing.