Armed with highly sensitive recording devices, state biologists are chasing bats through Wyoming in an emergency effort to identify and locate the species before a deadly disease grips Wyoming populations.
Earlier this year, researchers discovered the first bat in Wyoming that had the fungus that causes white-nose syndrome. The disease has devastated bat populations in the eastern U.S. and is making its way west. The number of bats has dropped so dramatically that some are being considered for listing on the Endangered Species Act, said Nichole Bjornlie, nongame mammal biologist for the Wyoming Game and Fish Department.
“The northern long-eared bat is [listed as] federally threatened,” she said. “The tricolored bat is petitioned for listing.”
Even the most common species across the country and in Wyoming, the little brown bat, has received a request by the U.S. Fish and Wildlife Service to evaluate their status, Bjornlie said.
“It’s one of the hardest-hit species,” she said. “We’re looking at 90-95 percent mortality in the face of white-nose [syndrome].”
The May 16 discovery of the fungus doesn’t mean the bat confirmed to have pseudogymnoascus destructans (PD) has white-nose syndrome. But detection sounds the alarm that the pathogen — which has killed millions of bats in the eastern and midwestern U.S. since it first appeared in New York state in 2006 — will soon grip Wyoming’s bats.
“Once a state in our latitude detects the fungus, it’s usually two to three years until white-nose syndrome takes hold,” Bjornlie said.
Bats are true hibernators. When healthy, they wake on occasion during the winter, moving to a new place in their hibernaculum (bat home) or drinking the dew that collects on their fur while they sleep. But each time a bat wakes up, it’s a huge energetic cost.
“There’s something about the fungus that makes them wake up more often [during hibernation]. It’s dehydrating, it’s irritating and it’s painful,” Bjornlie said. “They have a set amount of fat reserves built up so they’ll blow through [the reserves] faster and die from starvation or leave the hibernaculum looking for food and die of exposure.”
An important part of the state’s biodiversity, Wyoming has 18 species of bats. With 120 species of mammals in the state, bats represent 15 percent of the total population of Wyoming’s mammals. Very little is known about Wyoming’s bat populations, making research and discovery tough, she said.
“Bat observation is hard. We have to use specialized equipment and have special permits,” said Laura Beard, the Game and Fish bat specialist. “They’re cryptic and [observations] have to be done at night,”
Scientists, researchers and technicians are working on grid cells assigned through a national study in known bat habitats. Determining where best to put recorders within the cells can only be decided by exploring the areas. On Saturday, Game and Fish employees hiked through habitat near Ten Sleep looking for water (where bats drink and eat) and cliffs (where they roost). The hot sun and difficult terrain tested the team as they hoped to get a half-dozen recorders installed in a mix of public and private land.
Cells in Park County are in more vertical locations, requiring more time to find and install, Beard said. For four days, in 30 habitats across the state, researchers will record the echolocating sounds that bats use to navigate in the dark. The recordings will help identify the species of bats in each habitat — something that’s largely unknown to date.
Finding roosts and hibernacula in Wyoming rugged terrain is extremely taxing. Bats like caves, nooks and crannies in sheer cliffs, making them near impossible to find and reach in a state with uncountable suitable habitats. And unlike populations in the eastern U.S., Wyoming’s bats gather in much smaller groups. While a hibernaculum on the East Coast may contain thousands of bats, 15 bats hibernating together in Wyoming is a large colony, Bjornlie said.
After the recordings are complete, researchers will analyze thousands of hours of data. The spotted bat is the only species in Wyoming which humans can hear echolocating. Fortunately for researchers, an automated classifying app has been developed to analyze the data automatically, saving all but a few hard-to-distinguish sounds from being handled individually.
This will not be a short-term effort. Bat research can take decades to collect and analyze, Bjornlie said. Eventually, the research may shed light on the mysterious species, largely unpopular with the general public. Protecting bats would be easier if they had a positive reputation; stereotypes, solidified in horror flicks, have led to the species being demonized.
“People have different fears,” Beard said.
The researcher, originally from Alaska, admires the species, which are both amazing aerial acrobats and important species for insect management. A single little brown bat can eat up to 1,000 mosquitoes in a single hour. They are major predators of crop-damaging insects, too.
Amazingly, bats are one of the world’s longest-lived mammals for its size.
“A mouse that lives three years is an old mouse. Bats, about the same size, can live 25 to 30 years in the wild,” Bjornlie said.
But don’t make the mistake of calling a bat a mouse with wings. Bats are more closely related to humans and other primates physically than they are to rodents. Bats are the slowest-reproducing mammals on earth for their size, typically giving birth to only one pup per year. That makes the species more vulnerable to extinction in the face of what could be a massive die-off.
There is some light at the end of the tunnel: Researchers have been working on two somewhat promising treatments for the syndrome. One is an oral vaccine given to each individual bat. A similar treatment has been used on prairie dogs to help develop resistance to sylvatic plague. But unlike the ground-dwelling rodent, bats eat insects in mid-air and the time and resources it would take to do individual inoculations would be an all but impossible feat.
Another treatment involves exposing bats to ultraviolet light in the hibernaculum. While tests are showing promise, one problem is the light will kill additional varieties of fungus that other creatures need to survive. Testing the environmental impacts of either option could take many years. And Wyoming’s bat habitats and the species’ dispersed nature in the state provides added complications.
“Implementing a strategy that removes the fungus from a hibernation site isn’t going to be feasible for us because we don’t know where they are,” Bjornlie said.