The 10,000 bats that have hibernated in an abandoned iron ore mine in Upper Bucks for generations were wiped out by a disease that has been killing bat colonies across the Northeast at an alarming rate.
When Pennsylvania Game Commission wildlife biologist Greg Turner last checked on Upper Bucks’ bats in the spring of 2011, he found near devastation. Only 123 bats had survived, and half of those had fungus around their muzzles; a tell-tale sign they wouldn’t live to see winter.
The Durham bat mine was the second largest known bat habitat in Pennsylvania. Now, the ability of about 50 bats to resist the white nose syndrome, make it through the winter and reproduce this summer will determine the future of bats in Bucks County for generations.
This month, the surviving bats, which hibernate in a gated mine tucked into a Durham hillside, are feeding on insects across the region. Often called the “farmer’s friend,” bats hibernate each winter and spend the spring and summer months consuming hundreds of tons of nighttime insects.
At this time of the year, female bats typically gather in maternity colonies to deliver their newborn pups. In mid-July, the pups will learn how to fly and find food. Bats live 30 to 40 years in the wild, and only have one pup a year.
Game commission scientists are asking residents who find groups of bats to count the bats and report their findings to the state. To obtain applications and information on how to participate, visit the Game Commission’s website at www.pgc.state.pa.us.
In this season, any group of bats would likely be females gathered in a maternity colony, said Turner.
“Pennsylvania’s two most common bat species, the little brown bat and the big brown bat, use buildings as their summer roosts,” Game Commission wildlife biologist Calvin Butchkoski said in a written statement. “Abandoned houses, barns, church steeples — and even currently-occupied structures – can provide a summer home to female bats and their young.”
Pennsylvanians can play a significant role in helping the Game Commission get a better understanding of what is happening to bats this summer, said Butchkoski.
The white nose syndrome epidemic has struck numerous bat colonies in Pennsylvania, New Jersey, and across the Northeast.
The syndrome causes a white fungus to form around the nose of infected bats. They lose the body fat needed to survive hibernation and ultimately the mammals starve to death during the winter months. More than a million cave bats have died in the last five years, according to the Pennsylvania Game Commission. There is reportedly no threat to humans.
In January 2011, biologists first discovered signs that the disease had spread to the bats in the Durham mine, and it was too late to save them. By March 2011, 99 percent of Upper Bucks’ bats were dead.
Though scientists are still uncertain how the disease is spread, they hypothesize that cave explorers inadvertently picked up fungus spores on clothing and gear while exploring European caves, and then used the same, unwashed items to explore caves in the U.S.
This year, biologists won’t be checking on the Durham bats.
“When this started, we (biologists) really wanted to be hands-off as much as possible,” said Turner, noting that scientists were concerned that they too could unknowingly spread fungus spores among the bat caves. “We didn’t want to exacerbate the problem.”
Turner and his team do not plan to enter Durham’s bat mine until sometime between next January and March. The scientists will be counting the bats as they hibernate deep in the mine, and will be checking for any further signs of white nose syndrome.
It’s essential to wait two years after first discovering the disease among a bat colony in order to accurately measure if the surviving bats have delivered viable pups, said Turner.
If those juveniles are healthy, it could indicate that the surviving bats have a genetic trait or carry a bacteria on their skin that helps the bat to overcome or become immune to the disease, said Turner.
If the biologists find few pups or if they too show signs they have contracted the disease, it would be the worst-case scenario.
“If we lose 95 percent of the juveniles every winter, recovery is going to be extremely hampered,” he said.
If those few surviving bats can’t produce healthy young this summer, it could mean the end of the county’s bat population.