Bat-Killing Fungus Arrives In Wyoming, Will Likely Spread

Jun 8, 2018

In mid-May, field technicians with the Wyoming Natural Diversity database went up to the Fort Laramie Historical Site for a week-long survey, looking for white-nose syndrome (WNS) for the first year. They were looking for any species of bat that showed signs of the fungal disease, but ended up evaluating little brown bats.

Ian Abernethy, lead vertebrate zoologist for the Natural Diversity Database, said, up until now, there’s never actually been a case of the fungal disease in Wyoming, "but they also, during that occasion, noted a lot of scarring and necrotic tissue on the wings which is pretty unusual to see in a large number of bats."

He said the tissue was the first sign something strange was going on, but then something else showed up. Technicians noticed discoloration on the animals’ wings with a UV flashlight.

"Clearly between having that number of bats with scarring on the wings and that fluorescence, well, something’s weird here," Abernethy said.

White-nose Syndrome occurrence map - by year (2018).

The scientists set up a volleyball-like net and caught 205 bats. They swabbed ones that looked potentially diseased and inspected them with the UV light. 46 were evaluated in total. And sure enough, the fungus in question showed up.

"Only one of them had enough DNA… to detect the fungus on it," Abernethy said.

One out of 46 had the fungus (Pseudogymnoascus destructans fungus or Pd) that leads to WNS. That may seem insignificant, but Abernethy said it’s enough to be concerned.

“It’s very likely that that fungus will be transmitted to additional individuals and ultimately will probably affect many more than just that one,” he said.

Bats get a bad rap in pop culture, but they save around $3 billion dollars a year in pest services. Now, for the first time, Wyoming is facing its first case of the rapidly-spreading, bat-killing Pd fungus. It's known to cause WNS, a disease that's already killed millions of bats across the eastern U.S. and Canada.

The fungal disease kills bats in kind of a sneaky way. The fungus attacks when they're most vulnerable: during hibernation when bats have a reduced metabolism and energy level.

Blue-green fluorescence and lesions on the wing of a little brown bat at Fort Laramie. While this type of fluorescence is not characteristic of Pd or WNS, the lesions were suspicious and provided an indication that something unusual was occurring in the bat population here.
Credit Peter Kienzler, Wyoming Natural Diversity Database

Michelle Verant, wildlife veterinarian with the National Park Service, said, "This fungus gets onto their skin, usually the wings, and it starts to invade the surface of their skin and damage the wing tissue, and the wing serves a lot of important functions for that bat.”

She said it throws off heat balance, energy levels, pH levels, and electrolytes, then "the bat arouses more frequently during hibernation. It causes it to wake up more often."

That’s really not supposed to happen. So, typically, the bats die from starvation or cold temperatures. Mortality rates differ, but can be as high as 90 to 100 percent.

"New York was where it was first identified. And that was back in 2006, 2007. We found it because there were large groups of bats that were dying in caves in the winter,” Verant said, not meaning ‘we’ literally.

Verant said spores of the fungus were likely brought to the U.S. by people from Europe or Asia around that time the 2000s. And in the 12 years since it was first identified here in the country, WNS has spread incredibly fast with millions of bats dying in its wake. There are pockets of it in almost every state east of Wyoming, but now that it’s here, scientists like Verant are very concerned. She said, though only one case was identified in Fort Laramie, it’s safe to assume it is elsewhere in the state and that it will continue to grow since scientists can’t exactly limit bat movement.

"At this point, I think all the evidence suggests that we could see declines similar to what we’ve seen in the east in bat populations here in the Midwest and in the Western part of the U.S.," Verant said.

Bat house at Fort Laramie National Historic Site that supports a maternity colony of little brown bats. The bat in which Pd was detected was roosting in this bat house.
Credit Ian Abernethy, Wyoming Natural Diversity Database

In other parts of the country, its only taken two to three years to wipe out a given colony. There’s no large-scale treatment yet for WNS. But Verant explained Wyoming does have a response plan and it starts with gathering more data.

"Some of that involves doing additional surveys and surveillance to understand what species are infected with this fungus and in what areas of the state to understand how its spreading," she said.

Nicole Bjornlie, a non-game mammal biologist with the Wyoming Game and Fish Department, said communication and coordination are big parts of that plan. She said many different agencies will work to keep tabs on these bats. And as far as communication, that’s where humans come in. While white-nose doesn’t affect us, we can transport it.

So Bjornlie said, be careful and “[make] sure that if you go into caves and mines you decontaminate your gear… staying out of caves and mines that have been closed. And, also, something as simple as, if you’re vacationing, checking your umbrella, checking the canopy on your camper, before you leave just to make sure there are no bats hiding in there.”

The stepped-up surveying and data collection won’t begin until closer to winter when hibernation comes, but it’s not a bad idea to keep an eye out for hitchhiking bats on your vacation this summer.