Why are blind birds appearing around D.C.?

Wildlife experts say a high numbers of birds in the Washington, D.C., area are turning up blind, often dead or dying, but they don’t know what’s causing it.

The Washington Post reports that the Animal Welfare League of Arlington, Virginia, released a public service announcement alerting residents about the problem.

“Eye issues were reported in what otherwise looked like healthy juvenile birds, causing blindness and the birds to land and stay on the ground,” the announcement says. “Animal Control is now seeing additional species of birds affected. Other agencies and localities across the region and state are reporting similar issues at this time.”

Most reports have involved common grackles (Quiscalus quiscula) and blue jays (Cyanocitta cristata).

“The volume of reports and clinical signs are not suggestive of something that we have seen routinely in this area, so we may be dealing with an emerging or novel issue,” Megan Kirchgessner, of the Virginia Department of Wildlife Resources, told the Post.

Watch a video of an affected grackle below, and read more from the Washington Post.