Afield: What’s causing the mysterious bird deaths occurring in most of Pennsylvania?

In late May, wildlife rehabilitators in and around Washington, D.C., began receiving abnormally high reports of dead or sick blue jays, starlings, grackles, robins and other songbirds. The phenomenon spread quickly, and by early July, people in 10 states, including Pennsylvania and as far west as Indiana, were seeing the same thing.

Birds have been observed with crusted eyes and what appears to be neurological issues — not being able to perch, fly or walk normally. In some cases, birds have been found dead in large numbers. The affected birds are mainly recent fledglings.

The Pennsylvania Game Commission issued an alert on July 1 asking people to take down their bird feeders and to disinfect and empty their bird baths. This, as the theory goes, would stop birds from congregating and therefore slow the spread of the disease, if it is a disease.

By the end of June, the phenomenon involved just southeastern and central Pennsylvania, according to the Game Commission, with a total of 27 cases. As of July 8, the problem had spread to 61 of Pennsylvania’s counties and included 1,525 reports. Based on previous reports, researchers estimated that about 500 of these Pennsylvania reports are likely associated with the current songbird mortality event.

Although no county breakdown was available, there were 56 reports from the PGC’s Northcentral Region, which includes Centre County and neighboring counties to the north, east and west. There were 233 reports from the Commission’s Southcentral Region, which includes Blair, Huntingdon and Mifflin counties.

There has not been a numbers update since July 8. Since the problem has been observed in almost the entire state, the University of Pennsylvania School of Veterinary Medicine’s New Bolton Center and Penn State’s Animal Diagnostic Laboratory have stopped tabulating statistics for the public and concentrated on discovering the cause.

“We’re moving away from tallying the number of sightings from the general public at this point,” said Martin Hackett, communications director for the University of Pennsylvania’s New Bolton Center. “We’ve received a significant number of those, and we’re thrilled with the public’s response. The investigation has now progressed and shifted to strictly lab diagnosis — running and refining a battery of tests to identify cause. We still do not know the cause — and the diagnosis of this unknown illness will take time.”

While an exact cause has not been identified and diagnostics are ongoing, the following pathogens have been ruled out: salmonella, Chlamydia, avian influenza virus, West Nile virus, Newcastle disease virus, herpesviruses, poxviruses and trichomonas parasites. According to the Game Commission, there are no new developments on the diagnostics side, with multiple test results still pending at New Bolton Center and Penn State’s Animal Diagnostic Laboratory.

Early speculation included a connection to the emergence of cicadas from Brood X. Although this has not been totally ruled out, researchers say that this is unlikely a valid assumption. The problem is occurring in many areas that did not experience cicada emergence.

Reports have slowed in some of the other affected states, but I was unable to confirm that for Pennsylvania. Researchers and the Pennsylvania Game Commission are still recommending that feeders and birdbaths be taken down as a precaution.

“The good news is that there is no evidence of this disease in hummingbirds,” said Erica Miller, field operations manager for the Wildlife Futures Program at the University of Pennsylvania. “However, since we don’t know what is affecting the other songbirds, but we do know that few if any of the affected birds are surviving, we are being overly cautious and suggesting that all feeders and birdbaths be taken down in counties where sick and dead birds have been found.”

If you have not taken down your bird feeders, it would be wise to clean them regularly with a 10 percent bleach solution and discontinue feeding entirely if a sick bird is observed. If you have “heavy traffic” at your hummingbird feeder and would like to continue feeding them, Miller said, you should only make up small volumes of nectar at a time and change it daily.

“In the hot weather, not only will this protect against this possibly mystery disease, but it will also prevent the accumulation of mold spores that we know will sicken hummingbirds,” Miller told Robyn Graboski, of Centre Wildlife Care.

Research continues into determining the cause, but it is not an easy process.

Added Hackett: “What really matters here is what is causing it. And we don’t know yet.”

This story was originally published July 17, 2021 at 5:04 PM.