Indiana officials are asking people to take down bird feeders as they try to determine an unexplained increase in sick and dying songbirds.
The Indiana Department of Natural Resources has counted 285 ill or dead birds since May.
The Indianapolis Star reports that officials aren’t sure what’s causing the birds to become ill, including eye swelling, crusty discharge and neurological issues.
Early tests determined the birds did not have avian flu or West Nile virus. Birds that have been affected include blue jays, American robins and Northern cardinals.
“I like to compare it to trying to find an unknown object in a haystack,” Allisyn Gillet, an ornithologist with the state’s division of fish and wildlife, said. “I wanna say needle in a haystack, but we don’t even know what that needle looks like. We are trying our best to figure out exactly what are causing these symptoms and trying to rule things out.”
In the meantime, state officials ask residents to take in any bird feeders and baths to prevent birds from gathering there and transmitting the disease to others.