As winter approaches, a group ventures into the depths of Cameron Cave to collect data on a bat population threatened by a deadly fungus. With a treatment showing positive results, this could be the most important bat hibernation season since the detection of white-nose syndrome in the U.S. in 2006.

In the near blackness and total silence of Cameron Cave on the grounds of the Mark Twain Cave Complex, a voice rings out.

“I got one!”

The sounds of footsteps pick up as they converge on where Susan Wilkinson stands, her eyes pointed up towards the ceiling of the cave.

“There, you see?” she asks, pointing at a small brown spot on the wall.

To an unpracticed eye, the brown spot is barely distinguishable from the hundreds of brown rock nodules scattered on the walls of the cave complex. But to Kirsten Alvey-Mudd, executive director of the Missouri Bat Census, that little brown spot on the wall is the sole reason why she, husband Jim Mudd and Wilkinson trekked into the cave Tuesday, Oct. 20.

Immediately, the group stops, unloads backpacks and goes to work.

Alvey-Mudd uses a small net gerry-rigged with a blacklight to cautiously approach the little brown bat perched on the wall.

“Lights off,” she said, as the group instinctively shutters the light of headlamps.

A moment of darkness for the eyes to adjust.

Then the purple blacklight becomes visible, the only sign of life in the still, pitch-black cave.

Alvey-Mudd inches the light closer to the bat. The news isn’t good. Even from a few feet away, a casual observer could notice a fluorescent glow on the bat’s muzzle, ears and feet. In the darkness, the green glow marks a more ominous presence in the cave than even the most vivid imagination could conjure: white-nose syndrome (WNS).

A moment later, with headlamps back on, Alvey-Mudd traps the bat in the net and brings it down to eye level.

Wilkinson sits down, clipboard in hand. This isn’t a typical caving expedition, but a research trip and the trio is here to collect data — and in this case, the bats themselves.

The bats collected Tuesday, more than 15 in all, aren’t the average bat.

They’re sick.

But they’re also leading the fight against WNS, a vicious killer that threatens to wipe out entire bat populations from Canada to the deep south, New England to Kansas.

Discovered in a New York cave nine years ago, WNS has several detrimental effects on bats. It can wither wings. It disturbs the torpor of hibernation, driving bats to cave entrances. WNS basically immobilizes bats and causes their starvation. No one knows for sure how it got to North America, but theories suggest cavers brought spores of P. destructans, the fungus responsible for WNS, on shoes and equipment from caves in Europe.

As bat populations declined, scientists began working on a treatment for WNS.

A major advancement occurred earlier this year, when Alvey-Mudd and several others released bats treated with the Rhodococcus bacterium back into the wild on the grounds of the Mark Twain Cave complex. The bats collected at the site south of Hannibal showed a positive response to the treatment.

The opening of a door, Alvey-Mudd said.

Now, as winter approaches and the hibernation season begins, it’s time to again monitor the bats, in what could be the most important bat hibernation season since the detection of WNS in the U.S. in 2006.

Back in the cave, Alvey-Mudd handles the bat, no bigger than a palm, with gentle hands.

“The is a female Mylu,” Alvey-Mudd told Wilkinson, referring to Myotis lucifugus, the bat’s scientific name.

Examining the bat, Alvey-Mudd recites several pieces of information to Wilkinson, who meticulously keeps records of each bat captured. She inspects the bat’s wings with the help of a headlamp.

“Do you see the scarring there?” she asks, pointing out abnormal patterns on the wing skin of the chirruping bat.

“You have a loud mouth,” Alvey-Mudd tells the bat as if rebuking a child. “But you’re not using it to eat” — a comment on the thinness of the bats found Tuesday in the cave.

Forearm length, body condition, weight, wing condition — all pieces of information recorded to compare to bats treated with Rhodococcus. Used for several industrial purposes like delaying the ripening of fruit, Rhodococcus acts as a fungal inhibitor. Georgia State University’s Chris Cornelison happened upon Rhodococcus’ effect on WNS almost by accident. It’s turned out to be a promising treatment.

Some bats received treatment at a lab near Columbia, Mo., while others received treatment inside Cameron Cave itself. Deep in the cave, in a part dubbed the “research area”, hooks bored into a low overhang once held baskets of bats, an infrared camera set up nearby to detect the movement of the bats.

Wildlife biologist Sybill Amelon said she felt “very, very encouraged from what we see in both the lab and here at field sites,” at the release of rehabilitated bats back in May.

The data collection performed by Alvey-Mudd and others will help determine if the treatment continues to work.

“I have a vested interest in seeing these bats get better,” she said, taking a break from the non-stop search for bats. She grew up here, as did husband Jim Mudd, the self-described “valet” of the trip.

Both worked as tour guides in Cameron Cave when it was a commercial cave. It now serves as a research habitat, accessible only by a faint wilderness road. The couple knows their way through the cave with ease, with side passages jutting off every few feet creating a confusing maze for a newbie.

Not without humor despite the serious nature of the work, Alvey-Mudd explained, “But I have a husband who still gets lost in Walmart.”

Wilkinson proved the lucky charm on this trip, spotting more little brown bats in side passages and easily-missed crevices than anyone else. She grew up near Mammoth Cave in Kentucky, but now interns with the Missouri Bat Census.

Late in the trip, Wilkinson spots another.

This bat fared no better than the earlier.

“She lit up like a Christmas tree,” Alvey-Mudd said with a sigh after turning off the blacklight. “And it’s not even November yet.”

The hibernation season won’t begin for a few more weeks, so most bats still fly around outside the cave environment. With the cold weather encroaching, it’s a frenetic race to beat WNS.

“WNS interrupts hibernation and we’re trying to interrupt WNS,” Alvey-Mudd said.

The best instrument for that interruption could be the Rhodococcus treatment.

“We’re trying to figure out how to best utilize this new tool in our toolbelt,” she said, as Wilkinson signaled another bat around the corner.

Reach editor Eric Dundon at .