An unidentified illness causing deaths among songbirds in Pennsylvania and surrounding states has state wildlife authorities asking people to temporarily take down their bird feeders.

Researchers are looking at many possible causes, including birds eating 17-year cicadas. The first cases were reported around the time of the emergence of cicada Brood X in late spring.

“There has been lots of speculation about whether or not there’s a connection between the cicadas and these bird illnesses. We do not know the presence or absence of cicadas during these mortality events. So their possible role is also being considered as we investigate a variety of diseases and toxins,” said Martin Hackett, a spokesman for the University of Pennsylvania School of Veterinary Medicine.

Reports of birds such as blue jays, starlings, and common grackles taking ill first emerged in Pennsylvania in early June. The symptoms include crusty eyes, eye lesions, and neurological problems, like falling over or head tremors.

Birds with similar symptoms have also been reported in Delaware Maryland, Virginia, West Virginia, with the first reports dating back to mid-May.

The unidentified illness has now been reported in 36 of the 67 counties in Pennsylvania. Carbon and Schuylkill County each had two reports, Monroe had one, and Northampton County had three. In all but two of the local cases, the birds had died.

The Carbon County Environmental Education Center has not admitted any birds with the illness. Red Creek Wildlife Center in Schuylkill Haven said it received two Blue Jays with the described symptoms about a month ago, but hasn’t seen any other birds with the illness since then.

A cooperative effort between the federal government and universities is looking into possible causes. The National Wildlife Health Center has received assistance from the University of Pennsylvania and the University of Georgia.

David Stallknecht, who leads the University of Georgia center looking into the illness, said that researchers hope to update the public soon on some of the possible causes that they have ruled out. He said they still don’t know if a single cause is to blame for all of the birds that have symptoms.

“Nothing has showed up yet that answers the question of why this is occurring,” Stallknecht said.

Stallknecht said while there is no established link to cicadas, the illness has been seen in some places where the recent Brood X emerged. He said the cases have been mainly in fledgling and nestling birds, and he has heard of adult birds eating cicadas to feed their young.

“Young birds eat almost a pure insect diet. But we’re a long way from making a connection to that particular pathogen,” Stallknecht said.

The birds’ breeding season and the cicada emergence will end later this summer. Stallknecht said if there is a connection, the illness will probably decrease, too.

Until the deaths stop occurring, state wildlife authorities are recommending people take down bird feeders and drain bird baths. Limiting areas where birds congregate could help stop the spread if it turns out that birds are transmitting it to each other.

Susan Gallagher of the Carbon County Environmental Education Center said that any place that birds are congregating creates the possibility of spreading illness. The center tends not to use bird feeders during the summer, for that reason and because there is abundant food in the wild for the birds.

Gallagher recommended that people who insist on keeping up their feeders clean them weekly, and if possible limit the use of pesticides so they don’t accumulate in birds who eat a lot of insects.

“All of these things are good for birds, and they need all the help they can get from us,” Gallagher said.