Around this time last summer, more than 1,000 dead birds with a mysterious illness were reported around Pennsylvania.
A year later, researchers say the outbreak appears to have vanished, but they still don’t know what happened.
The sick birds were typically found trembling on the ground, and their eyes had lesions and a discharge.
Peter Saenger, ornithological specialist at the Acopian Center for Ornithology at Muhlenberg College, says researchers have ruled out West Nile Virus, avian influenza and salmonella.
“They’ve ruled out pesticides, a myriad of regular diseases, and they have found nothing conclusive. It is sort of scary that they couldn’t figure it out because it killed an awful lot of birds,” said Saenger.
Saenger says it’s unusual for the source of such a widespread sickness to remain a mystery.
One theory is that the birds may have had issues digesting a generation of cicadas that emerged last year.
“They were finding a lot of young birds filled with the exo-skeltons of cicadas. So, they couldn't ingest more food, and it was clogging their digestive tracts,” said Saenger.
People had been asked to take down bird feeders and baths. But Saenger says since the illness is no longer a concern, it’s OK to feed the birds.
Read more from our partners, WLVR.
