So just how devastating has white-nose syndrome been for Pennsylvania bats? The short answer: It’s hard to see the situation getting much worse. In fact, it’s estimated that 99 percent of all the state’s hibernating bat populations have succumbed to the fungal disease since it first appeared in the U.S. about a decade ago. But Greg Turner, a biologist with the Pennsylvania Game Commission, says there may be some glimmers of hope in the fight to save Pennsylvania’s bats.
The Allegheny Front: You’ve been studying white-nose syndrome for a number of years. What can you tell us about how it’s impacting bat populations now in Pennsylvania?
Greg Turner: The hibernation studies we have show about a 99 percent decline overall—that’s all six hibernating species aggregated together. That’s pretty dramatic. But what we’re looking at is four species in particular that are highly impacted. And one of those was our most common species—the little brown bat. And we don’t know how many of them we had, but it was likely 3 to 6 million at least. And we lost 99.9 percent of those. The story is the same across the state. We had a massive die-off of the hibernating population for one to two years. From that point forward, the majority of the sites have just slowly trickled down, while a handful of other sites seem to actually be increasing [in population].
LISTEN: “Inside the Fight to Save Pennsylvania’s Bats”
AF: And how exactly is white-nose syndrome harming bats?
GT: So when bats come in contact with this fungus, it starts creating lesions all across their wing membrane. Once you get those infections, then the bats start arousing out of hibernation about twice as frequently as they should. And in order to come from the temperature of the cave, which is about 45 degrees, up to their normal warm temperature, which is about 100 degrees, it takes a lot of energy to do that. So they have enough energy to do that just a set amount of times every winter. And now, when they get this disease, they’re burning through [their energy] twice as fast. And that causes them to run out of energy in the middle of the winter.
AF: You mentioned you’re actually seeing an increase in bat populations at some sites. Do you have any ideas why?
GT: Bats are a gregarious species. They like to be together. So you have sites that used to hold thousands and thousands of bats, and now, there’s just a handful of bats left at that site. So I think they’re searching around for each other. And I also think they’re looking for sites that might give them a little advantage in surviving the disease. We have a paper in the works that actually shows the bats are choosing colder sites than what they preferred before the disease came. For example, if you can envision a railroad tunnel that’s about a mile long, about a third of it is frozen on both ends. But in the middle, you find this area where the temperature is 2 to 3 degrees above freezing. And that’s where we’re finding bats. And we think those colder temperatures allow the bats to save energy because they’re arousing less frequently in those colder areas. So they can save a little bit of extra energy and are able to deal with the disease better.
AF: Is there any new research or treatment that could help bats with white-nose syndrome?
GT: We’ve been involved in trying to find a treatment since it first came to Pennsylvania. A lot of the early things that we tried, even though they were benign, natural substances, were effective in the lab at killing the fungus. But we found the bats, while they’re hibernating, are so sensitive that the treatment was often more damaging than the disease. We’re keeping our eyes out for everything, including proactive bacteria that might help fight the fungus. One of the things we’re working on here is something we can put on the roost structure and prevent that environmental transmission [of the fungus] from even occurring. You know, these bats are creatures of habit. One of the particular caves I went in has a little nail hanging in the wall where there used to be a light. And for over a decade, I went in there and there was this one little tri-colored bat that would hang on that nail every year. So we can use that to our advantage: If there’s a particular area they like to go to, if we can put something on there to basically clean that roost of this fungus and reduce the amount of exposure they have, we might be able to improve the survival and decrease the amount of infection. It hasn’t been tried yet. So we’re kind of excited about that, and with our preliminary experiments, we are seeing some positive results.
AF: So is this a reason to be hopeful?
GT: I’m always trying to stay positive. It’s not an easy task. I don’t think there’s going to be a silver bullet that’s going to be applied to any given site or to bats directly that will take care of the problem. There may be certain sites where one tool will work really well, and at a different site, something else might work really well. I don’t want to doubt the species and how resilient they are to things like this. And to see them adapting and picking new sites and picking different ways to deal with the disease does give me hope.
Greg Turner is a biologist with the Pennsylvania Game Commission who has been studying white-nose syndrome in Pennsylvania bats for the past six years.