Groups of songbirds have recently been turning up dead throughout Montgomery County and surrounding counties. Their cause of death remains a mystery to scientists and wildlife officials, writes Frank Kummer for The Philadelphia Inquirer.

Similar deaths have been reported in other parts of Pennsylvania and across several more states, going back to April.

Experts characterize the rash of songbird deaths as unusual. They are appealing to the public to remove both backyard feeders and birdbaths to stem the tide. One theory holds that birds pass a fatal ailment when in close proximity.

Various species are affected by the unknown malady. They have all been found with ocular and neurological issues.

According to Lisa Murphy, a veterinarian and director of Pennsylvania Diagnostic Laboratory System at New Bolton Center in Kennett Square, scientists consider the illness “worrisome.”

“Not one disease or disease agent jumps,” she said. “This does seem to be something unique and unusual.”

To untangle the mystery, Pennsylvania officials are now asking people to report unusual occurrences of bird deaths to the Wildlife Futures Program.

Read more about the illness striking songbirds in The Philadelphia Inquirer.