Bats may have a spooky reputation, but the real horror story is the sharp decline of several local bat species in the past 15 years due to a disease called white-nose syndrome. The Indiana bat and the northern long-eared bat are both listed as federally endangered species, while the tricolored bat is proposed endangered.
White-nose syndrome has killed over 90% of the bat populations in these three species, according to the U.S. Geological Survey and U.S. Fish and Wildlife Service. It’s caused by a fungus called Pseudogymnoascus destructans, or Pd, and looks like a white fuzz on a bat’s face, like it dipped its nose in a white powder. Pd grows in dark and dank places, in the mines and caves where bats hibernate during the winter, called hibernacula. Nearly all hibernacula in Pennsylvania has Pd, according to the Pennsylvania Game Commission, the state agency responsible for bat conservation. There is no known treatment or cure for the disease.
“When it grows on the skin of a bat, it kind of causes them to change their behavior and they end up more active than usual,” said Sydney Giuliano, public affairs specialist for white-nose syndrome and endangered species at the U.S. Fish and Wildlife Service. “And during this hibernation is a time where they have very limited fat stores. So they burn up those fat stores and oftentimes it leaves them to die off. And unfortunately, this is a huge issue.”
Development can make the decline of these species worse and halt their recovery. Last week, the U.S. Fish and Wildlife Service sent out a new conservation plan to protect these bat species from habitat loss as a result of routine development — things like building houses, roads or utility operations — in Pennsylvania, New York and West Virginia. This voluntary plan gives developers a consistent permitting process for projects that might result in tree removal or disturb the caves and mines where the bats hibernate.
“It makes it easier for companies to kind of opt in and adopt this existing conservation framework,” said Pam Shellenberger, biologist at the Pennsylvania Ecological Field Services Office for the U.S. Fish and Wildlife Service. “And then it gives biologists like myself and wildlife managers assurances that these conservation measures are being followed and so that the bats are being protected.”
Protecting survivors
White-nose syndrome has been spreading across North America by near-invisible fungal spores attached to bats, humans or other wildlife. Right now, it is in 40 states and nine Canadian provinces. Millions of bats have died.
“This is considered one of the most deadly wildlife diseases that there has been,” Guiliano said.
White-nose syndrome first came to Pennsylvania in winter of 2008 and 2009. Since then, it’s decimated these hibernating local bat populations.
“We've kind of hit a point where we've kind of bottomed out, meaning like our numbers are not necessarily significantly decreasing anymore,” Shellenberger said. “But they've already really decreased by over 90% for most of these bat species. And now we're kind of in a situation where we have these survivors from white-nose and we're working to try to protect those survivors.”
Current conservation efforts center on supporting these white-nose survivors — those who get the disease but are only weakened or exhibit no symptoms at all. The goal is to protect the maternity colonies so the resilient bats can survive and reproduce.
After hibernating all winter, these bats species return to the same trees each summer, according to Shellenberger. During the warmer seasons, bats depend on the forest habitat and trees to live and eat. Bats use trees to find their next flying insect meal — like mosquitoes — and for roosting while they take care of their pups.
Some of these roosting trees can be hundreds of miles from where the bats hibernate. If those trees have been removed because of development, the bats must look for new roosting and foraging sites using fat reserves and energy that has already been depleted if they’ve suffered and survived white nose syndrome that winter.
“Habitat loss and development can really affect reproductive success for all the bats in Pennsylvania, including the ones that are really affected by white-nose syndrome,” Shellenberger said. Habitat loss can also break up maternity areas or groups of trees where groups of female bats raise their pups together.
The U.S. Fish and Wildlife Service’s conservation plan gives consistent guidelines for conservation measures that protect their winter and summer habitats. The conservation measures have different restrictions on tree removal depending on time of year, for example.
“It's important to not remove trees during the summer time frame when there are pups and the pups can't fly,” Giuliano said. “But other times, if you're near a place where bats hibernate, a cave or mine, [you should] not remove trees during the fall time frame when bats might be using the areas that are right outside of the hibernacula to cluster and actually meet and kind of investigate the hibernacula to make sure it's the right temperature and climate for them to hibernate in for the winter.”
Construction outside a cave or mine could impact the climate inside. Vibrations from blasting can cause shifts inside the hibernacula that could change the airflow or humidity where the bats hibernate.
