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Strenuous Ordeal in Arco Tunnel Boosts Bat Science

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Bat Country

National Park Service vegetation ecologist Jim Bromberg, left, points across the snow near the entrance of Arco Tunnel on Feb. 11, as he talks to Idaho Department of Fish and Game wildlife biologist Ross Winton, foreground, and NPS intern Arianne Millet. Craters of the Moon lead interpreter Sandra Gladish, second from right, listens as NPS wildlife biologist Todd Stefanic radios in the group’s location and time of entry into the cave.


ARCO • In the cold darkness deep inside Arco Tunnel, I lay on the hard lava rock, arms folded across my chest, my helmeted head resting on the ground. I switched off my headlamp, making the darkness complete, and drifted into sleep.

I had crawled into Arco Tunnel at Craters of the Moon National Monument and Preserve several hours earlier to observe a team monitoring bats to learn more about the creatures’ hibernacula behavior. But after several hours of crawling, shimmying, scooting and rolling through hundreds of yards of lava tubes, I had learned something about my own behavior: If I’m exhausted enough, I can sleep comfortably on rocks.

I made this discovery thanks to Todd Stefanic, the lead wildlife biologist at Craters of the Moon, and Virginia Hutchins, the Times-News’ enterprise editor. Hutchins convinced Stefanic to let a reporter follow him around a cave for a day, and on Feb. 11 I met up with him and four others to document the work they’re doing to study bat populations in southern Idaho.

Stefanic, who works for the National Park Service, spends about half his work time studying bats. It became an essential job function over the past decade as white-nose syndrome, introduced to the U.S. a decade ago, rapidly spread west and decimated bat populations.

Stefanic and others who study bats in southern Idaho are in the fourth year of a five-year survey to monitor behavior. After next winter, they’ll analyze their data and hopefully learn more about local bat populations — how they migrate, how they hibernate, which caves they like to hibernate in, which caves they don’t. With this information, they’ll be better prepared to enact conservation efforts and to study the effect of white-nose syndrome upon its inevitable arrival in Idaho.

“It’s important to build this baseline knowledge, to know what’s going on when white-nose finally gets here,” Stefanic said. “We don’t know a lot about what’s going on with them, especially in Craters.”

But to capture and record all this information requires physically demanding work.

“That’s why typically we only do one cave survey a week,” Stefanic said. “It’s labor intensive to get this data.”

• • •

I woke at 5:30 a.m. to arrive at Craters of the Moon by 8.

“There’s no relieving yourself in the cave,” Stefanic told me by phone on the eve of our adventure. “So don’t be drinking too much coffee on the drive up.”

I’m not a coffee drinker, but I took that advice seriously, skipping my usual fruit smoothie and instead munching an apple and nursing a small glass of orange juice during the two-hour drive to the park. Getting to Arco Tunnel would require a snowmobile ride and a snowshoe hike, so I wanted some liquid to hold me over, but not enough to make me miserable inside the cave.

Bat Country

Todd Stefanic drives a snowmobile toward Arco Tunnel on Feb. 11.


Never before had I considered that the work of wildlife biologists would require such specific dietary decisions.

I pulled into the parking lot at Craters of the Moon just ahead of Jim Bromberg, the vegetation ecologist at the park and one of the others who would go into Arco Tunnel that day.

Stefanic led me into the NPS office building, an old house converted into work spaces. As we started to pack our gear for the day’s excursion, I met the other members of our crew. Arianne Millet is a Student Conservation Association intern at the park who works with Stefanic. Sandra Gladish is the park’s lead interpreter.

“(Gladish) is fairly new,” Stefanic explained later. “I try to get her and other new interpreters into caves so they can speak to the public with first-hand knowledge of what’s going on.”

Last to arrive was Ross Winton, a regional wildlife biologist with the Idaho Department of Fish and Game.

Each of us packed a backpack and gathered the gear we’d need for the day, including motorcycle helmets for the snowmobile ride and snowshoes and ski poles for the trek to the cave mouth. Inside the caves, we would need coveralls, helmets with headlamps, flashlights and batteries, knee pads and gloves, plus the gear used to document the bats and their behavior — digital cameras, markers and dry-erase boards and an instrument for taking temperature and humidity readings.

Stefanic pulled us into an office to study a map of Arco Tunnel and go over the plan for the day. In the first part of the tunnel I could simply observe the scientists, Stefanic told me. Later, when the cave split into smaller tunnels, I’d pair off with Millet to help her search for bats.

• • •

Gladish and Millet took one snowmobile while I rode on the back of one Stefanic drove, which towed Bromberg and Winton on a Swede sled. Behind the passenger sled, we towed a sled full of gear.

The entire outing was almost cut short as Stefanic’s snowmobile began losing power just a few hundred yards from the office. After tinkering under the hood for several minutes, Stefanic fixed whatever ailed the machine and we were on our way.

About three miles to the southeast, we pulled off and cut the engines, then quickly prepared to snowshoe to the tunnel’s mouth. I had never used snowshoes before — something I didn’t tell Stefanic — but was able to keep up with the pace, hanging a little behind to photograph the others hiking.

We took a longer route than needed so Stefanic could swing by the entrance of Beauty Cave, a nearby lava tunnel where Bromberg and Gladish would explore and search for bats after finishing a short section of Arco Tunnel.

“Beauty and Arco were the same cave; when lava was flowing through there, it was all one tunnel,” Stefanic said later.

Bat Country

A bat monitoring team: National Park Service vegetation ecologist Jim Bromberg, left, slips on his coveralls Feb. 11 in preparation to enter Arco Tunnel. Craters of the Moon National Monument lead interpreter Sandra Gladish, center, watches as intern Arianne Millet, bottom, straps on her knee pad, while Idaho Department of Fish and Game wildlife biologist Ross Winton waits to enter the cave.


Part of the tunnel collapsed in the ensuing centuries, separating Arco Tunnel and Beauty Cave. But it’s important to monitor both on the same day to ensure that hibernating bats are not double-counted if they move from one to the other.

“That’s one thing that’s really interesting, is they wake up in the middle of the winter and fly around,” Stefanic said. “We don’t know exactly why. Do they need a drink? To defecate? To urinate? We don’t know, but we know bats will exit one cave and go to the other.”

After trekking past Boy Scout Cave and the brief stop at the Beauty entrance, we made our final approach to Arco Tunnel. Someone suggested that whoever needed to relieve themselves should do so now. I seized the opportunity.

• • •

At 9:58 a.m., Stefanic radioed in our group size and location. We ditched our snowshoes and climbed down icy rocks to a staging area created by a large, rocky overhang. We stripped off our backpacks and winter coats and pulled on coveralls — necessary for both protecting clothing and preventing the spread of white-nose syndrome, which can be transmitted on clothing and gear.

We strapped on knee pads, pulled on gloves and buckled our helmets as Stefanic unlocked a gate with wide metal bars. To keep humans from disturbing the bats, gates have been placed at some cave entrances in the park.

Stefanic said sarcastically that the gates are “bat friendly”; the creatures only tolerate the wide metal bars. He’s against putting gates at cave entrances, he said.

Later, Stefanic said he understands the gates help keep out graffiti artists and vandals, but they should be used as a last resort, if at all.

“People have watched cave entrances before and after a gate went in,” Stefanic explained. “Before, the bats would show up and glide in. But after, they sometimes swarm around the entrance before going in. It changes the dynamic and could even effect their choice of cave. Maybe they go on to a different place. Maybe it closes off their favorite roost.”

The six of us crawled through the opening.

• • •

Stefanic had told us an important rule: Don’t talk inside the cave. Especially don’t whisper, because even a whisper creates a sound disturbing to the bats. I quickly remembered this rule because the talkative group immediately went silent.

Bat Country

Townsend's big-eared bats (Corynorhinus townsendii) hibernate in Arco Tunnel on Feb. 11. 


Within 100 feet we left all daylight, and only our headlamps lit the path. Winton, Stefanic and Gladish immediately began searching for bats.

To the untrained eye, Arco Tunnel appears to end after only a short distance. We reached this seeming dead end without finding any bats. But the tunnel does go on, accessed by a belly crawl known as The Gate. One by one, we lay prone and scooted through. On the other side, the tunnel opened up enough for several people to walk shoulder to shoulder.

Past the first crawl, our group moved slowly with Winton searching the left side of the tunnel, Stefanic the ceiling and Gladish the right. Soon, we encountered our first bats, and Millet and Bromberg documented each one, a process that took several minutes.

First, Millet used a digital camera to photograph the bat or grouping of bats. She used the dry-erase board and markers to write what zone the bat was found in and how many had been found to that point. Then Bromberg took temperature and humidity readings, which Millet recorded in a notebook.

Working this way, we slowly moved through zones two and three as a group, documenting more than a dozen Townsend’s big-eared bats hibernating on the walls and ceiling.

• • •

At the end of zone three is The Forum, a wide opening. Here, we found several more Townsend’s big-eared, then someone spotted something else. It looked the same to me, but Winton mouthed that it was indeed a different species.

Bat Country

Idaho Department of Fish and Game wildlife biologist Ross Winton, left, crouches to examine an insect as Jim Bormberg, center, and Todd Stefanic help illuminate it inside Arco Tunnel on Feb. 11.


We took something resembling a break, giving Winton an opportunity to search for insects. Without sunlight, the insects inside caves are an almost translucent white. Winton used his mouth and a long hose to suction the insects and place them in vials.

It was also in The Forum where Bromberg demonstrated his specialty. He pointed my attention to the low ceiling where it looked as if red hair grew from a crack. I shrugged my shoulders and did my best to form a quizzical expression.

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“Roots,” the vegetation ecologist mouthed.

It was time to split up. I was paired with Millet, the student intern.

• • •

I learned quickly that looking for bats is significantly more difficult than observing others looking for bats. The first zone Millet and I were assigned to search quickly split into two tunnels, so I was tasked with my very own. But searching every inch of the walls and ceiling took a toll on my neck. Within five minutes my neck ached from constantly moving my light from the left wall, to the ceiling, to the right wall, and back.

It’s not good enough to simply walk down the center of the tunnel. If there was a ledge in the wall, I had to crawl under the overhang to check for bats. If there was an area where the ceiling jutted upward, I had to climb the best I could or strain to see the top. And ever since we left The Forum, the tunnel we were surveying got smaller and smaller. By the time I rejoined Millet, we were crouching in some parts, crawling in others.

We moved several hundred feet together, Millet checking the right half of the tunnel and me the left, at some points able to walk upright, but most of the time squatting or crawling. We found no bats until we reached a bend where the ceiling was higher. Searching the crevices, I finally spotted something fury tucked inside a deep nook in the ceiling.

Millet documented my find, and a few minutes later I made my next: two hibernating bats bunched together on a low wall.

As the tunnel narrowed, soon we were crawling on all fours. And it simply continued on and on, curving at times, with our headlights not strong enough to reach any sort of end or show us an area we might be able to stand. So we crawled, finding no bats for hundreds of yards.

Finally, we reached an area where the tunnel widened a bit, though it didn’t get taller. In the distance, we could see Winton’s and Stefanic’s lights approaching. We had apparently reached some predetermined meeting place I heard Stefanic and Millet talk about hours earlier.

I covered my headlamp so as not to blind my companion and stuck my tongue out the side of my mouth to express my exhaustion; Millet nodded in agreement. Then she pointed at me and pointed down, motioning for me to stay put. She pointed at herself then toward a small crack between the left wall and the ground.

Bat Country

A crumpled map shows notes written by National Park Service wildlife biologist Todd Stefanic after monitoring bats Feb. 11 inside Arco Tunnel.


Exhausted and thirsty, I was happy to wait while she explored. Unable to stand and stretch, I lay on my back and turned off my headlamp, ushering in utter darkness. My body ached, and a check of my phone, which I was using as a camera, showed we had already been inside Arco Tunnel for four hours. I welcomed the pure darkness and peaceful quiet of the cave and drifted off to sleep.

I awoke moments later, looking to my right to again catch a glimpse of the lights from the two biologists. I rolled my tired body and crawled toward the two men. Neither group had seen bats for several hundred yards in each direction, so we determined it was OK to speak quietly. Stefanic seemed surprised when I told him we found hibernating bats in the zone we searched — in previous years, bats typically hadn’t been found there.

Millet soon emerged and the four of us crawled toward — what, exactly? I wasn’t sure at that point, my mind turning increasingly to the two things my body wanted most: to drink water and stand up straight. Finally we reached an area where the tunnel ceiling rose, allowing me to stand for the first time in at least an hour.

“Glorious,” is the word I scribbled in my notebook.

Soon enough, we were crawling again, this time toward a dead end. Stefanic disappeared, later reappearing and telling us he had just found a new section of undocumented tunnel that required an extremely tight crawl to access.

After reaching the dead end without finding more bats, we crawled back the way we came. At one point I saw Stefanic cross his arms across his chest like a mummy and roll, not unlike a child rolling down a grassy hill.

• • •

After crawling, then walking crouched over, we finally could walk upright. Sooner than I expected, we arrived back at The Forum and were able to walk upright the rest of the way until the crawl at The Gate. With exhaustion setting in, it took me twice as long to crawl under The Gate on the way out.

Back in the staging area a few minutes later, my mind could focus on only one thing: dehydration. I hadn’t had a drop of water to drink all day, and the bottle I brought with me I’d left back at the office.

Winton came to the rescue, offering me one of the two bottles he had in his backpack. I was thrilled to accept and gulped downed most of the bottle before we left the staging area.

At 3:09 p.m., Stefanic radioed in that we were all out of the cave and heading back soon.

We were supposed to disinfect our gear then and there, but the Clorox wipes and Formula 409 cleaner we’d brought along for the job were frozen. We’d have to disinfect when we got back to the office. Stefanic had planned for that contingency, though, telling us before we left to bring trash bags. We each stuffed our coveralls, helmets, gloves and knee pads into bags.

The snowshoe trek back to the snowmobiles, although supposedly shorter without the detour to Beauty Cave, seemed to have doubled in length. By the time we motored back to the office, it was after 4 p.m. We wasted no time in shedding gear and heading our separate ways.

My knees were tender from crawling all day, even with the knee pads; my neck ached; my back was sore; my arms were noodles. And the next day I became aware of muscles in my core that I hadn’t known existed.

Exhausted, I rested in my truck for a moment, reflecting on the physical demands of these biologists’ jobs — and appreciating the type of person it takes to do this vital work.


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