Bats are in trouble. This week, the U.S. Fish & Wildlife Service proposed shifting one species, the northern long-eared bat, from its current threatened status to endangered. This is a result of white-nose syndrome.
Once abundant in Wisconsin, the number of northern long-eared bats in the state has declined by 99% — and that's just one of many species impacted by a deadly fungus.
But scientists are looking for solutions to save bats, including a team from Virginia Tech.
Recently five researchers clustered outside the bat hibernation location in southwest Wisconsin. They don head-lamped helmets, disposable gloves and hazmat suits — to keep them from spreading disease from one hibernaculum to another.
This bat hibernation site is one of 250 in Wisconsin. Associate professors Kate Langwig and Joe Hoyt along with their grad students survey in partnership with the Wisconsin Department of Natural Resources.
Many of the sites are privately owned. The DNR tries to keep the locations hush-hush because it’s critical the bats remain as undisturbed as possible during their hibernation period, October through mid-May.
Why is bat hibernation so important? Well, some bats, depending on the species, only take a breath every 10 minutes and their heart beat as little as four times per minute. Disturbing the bat can trigger a slow and laborious waking up process that can result in much-needed fat reserve being burned.
All I can say about this site in southwest Wisconsin is its caverns are beneath a large, old building with plenty of opportunities for bats to find their way inside, and the property owner has become a bat advocate and is delighted to see the researchers return.
Once underground, the researchers quietly set to work, searching every chilly crevice for drowsy bat — often tucked out of sight. The team notes the temperature.
From a distance the bats appear to be little reddish-brown balls of fur.
The team inspects each bat for evidence of fungal invasion. That means looking for areas covered with the white-colored fungus or for wing damage caused by it.
One team member takes a sample of the bat’s skin by swabbing its muzzle and forearm and then weighs it.
This one weighs 15.42 grams — that’s just more than a half an ounce — the weight of three quarters. A bat can lose up to a third of its body weight during hibernation.
This bat is already banded, but if it weren't, an aluminum lipped bracelet would be affixed around its forearm.
Then the bat is gently placed back where it came from.
Over the years, four bat species have been monitored at this site, including the northern long-eared. Sometimes as many as 16 bats have been found hibernating here. This year, only six were found — all of them of the big brown species.
Scientists have learned the deadly white-nose fungus thrives in the same dark wintery conditions in which bats hibernate, and bats are really good at spreading the fungus around.
In addition, the fungus lives on — even if bats aren’t there.
Back in the open air, Kate Langwig says although they weren’t able to stop white-nose syndrome in its tracks, by getting to Wisconsin in 2012 before the fungus struck, they started amassing useful information. “About what does the disease do to populations as it first invades, how do we see prevalence of infection change, how do we see the intensity of infection change," she explains.
Now they’re focusing on characterizing the survivors. “With this really, really virulent disease that killed 95% of bats when it first arrived. Individuals that are surviving, so we have a couple of bats here that are survivors, right? What’s special about the? How are they able get through this?"
Langwig’s team is studying how temperatures and humidity where those bats hibernate factor into the puzzle. “Our research has found that within the range that bats hibernate, the warmer temperatures, the warmer caves, the fungus grows a little faster, kills the bats faster."
At the same time, her lab is uncovering evidence that surviving bats are developing resistance to the disease.
Langwig has been studying bats for 15 years, ever since white-nose syndrome first emerged in the U.S. and has a long list of reasons why bats fascinate her, beyond the volume and variety of insects they consume.
"They’re, of course, our only flying mammal. [They have] one of the most diverse diets of any taxa on the planet. They’re having a sort of double affect at helping out crops and probably forests and other ecosystems. They’re really an important species.”
Langwig believes it’s profoundly important to save the creatures. “They only have one baby a year, so unfortunately it will take them a really long to recover but I hope it also demonstrates to people how interesting they are."
She’s cautiously optimistic. Her team is seeing individual bats with the disease survive the winter, and she hopes to help uncover what makes their survival possible.
As for the northern long-eared bat, the U.S. Fish & Wildlife Service is holding avirtual public information meeting and hearing on April 7.
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