ORANGE COUNTY, N.C. (WTVD) -- If you are a longtime bird watcher or one of the legions who have started that hobby while stuck at home during the pandemic, you may have heard there's a mystery disease affecting songbirds in the eastern United States.
It's just the latest assault on those birds, which have seen a 25% decline in their population in the past 50 years.
While there are many newcomers to the so-called "birder" community, some like Isabell Reddy of Orange County have been bird-watching for many years.
"It is the least expensive, the most friendly hobby," she said this week in her backyard.
More and more birders are noticing sick songbirds Reddy said.
"They have found birds with an eye disease, and a neurologic disorder. And they're dying even in the care of rehabbers and scientists."
"We don't know exactly what it is, we've been trying to monitor it," a bird expert who works for the North Carolina Wildlife Resources Commission, Falyn Owens, said.
The commission recently posted about the mystery disease.
"We put information on social media just to let people know that if they see anything suspicious that they should let us know," Owens said.
An ABC11 viewer in Moore County sent pictures of a bird at a feeder in her backyard with swollen eyes.
Owens looked at the pictures and said she doesn't think it's the mystery disease.
"What's most likely responsible there is something called avian conjunctivitis," she said.
Owens says that's basically like pink eye in humans.
The mystery disease not only affects the eyes of songbirds but causes them to have seizures and other neurological symptoms.
It's just another problem with the ongoing threat to songbirds from diseases and domestic predators such as cats.
Their populations are declining.
"One in four are gone in the last 50 years," Reddy said.
Some ornithologists think bird feeders and bird baths are part of the problem because, like humans, birds spread diseases when congregating.
That's why Reddy has been following the advice of the state Wildlife Resources Commission to take down bird feeders and bird baths until someone figures out the mystery disease.
But even when they are allowed again, she knows to disinfect them frequently.
Ornithologists like Owens would like to see birders eventually stop using feeders altogether and instead start planting native trees and shrubs that produce berries and other food sources for birds to forage.
They say that will still allow for great backyard bird-watching while protecting them at the same time.