Endangered Indiana bat mostly gone from southwestern Pa. but longer migration holds hope

The tiny wings of the endangered Indiana bat seem to be taking the creature on longer journeys.

The Pennsylvania Game Commission recently documented the longest known, single-season migration of the federally and state-endangered bat from Pennsylvania to Kentucky.

As the migration, at least 418 miles, broke the record for longest migration for the Indiana bat — 320 miles — the mammals’ presence at winter hibernation sites called hibernacula in Southwestern Pennsylvania continues to plummet.

The Indiana bat no longer is found hibernating in a mine straddling Armstrong and Butler counties, where 100,000-plus bats of various species once hibernated, said Greg Turner, state mammalogist for the Pennsylvania Game Commission.

The bat recently was verified in Southwestern Pennsylvania at only two hibernacula in Somerset and Fayette counties, Turner said. The number of known Indiana bats hibernating in those counties is only four of five.

With a wingspan of 3.5 to 5.5 inches, the bat typically hibernates in limestone caverns and abandoned mines. Known as a social bat, the Indiana hibernates with its own and other species, Turner said.

The Indiana bat breeds in the summer at maternity sites in small colonies under loose tree bark. Surveys in the winter when the animals are hibernating are the best population indicators because their breeding grounds are more dispersed, species-specific and not as easily gauged, Turner said.

The deadly disease white-nose syndrome caused all bat populations of six species that hibernate in Pennsylvania to crash by 98% in the past decade or so, he said.

The Indiana bat was found hibernating at 20 sites before white-nose syndrome hit the state. Now, researchers can find them at only four winter sites, in Blair, Somerset, Fayette, and Luzerne counties, Turner said.

The recent long-distance migration of the Indiana bat, which was banded and outfitted with a transmitter, is a positive sign that the bats might be hibernating elsewhere, Turner said.

Turner and a team of researchers have connected the bat to hibernating populations in New York, New Jersey, Wilkes-Barre, Pa., and now Kentucky.

“We know we lost a lot of bats from white-nose syndrome. With the Indiana bat, it’s possible the mortality wasn’t as bad overall,” Turner said. “The fact we have four to five sites in the Midwest where the population didn’t decline may be evidence that some of the survivors have retracted back to their core range.”

The game commission will continue to study population declines and possible interventions to help the state’s hibernating bats better survive, Turner said.