Glacier's bat inventory and monitoring program: Using partners, collaborators, and volunteers to make it a success

By Lisa Bate

Little brown bat in gloved human hand (Copyright Kristi DuBois, all rights reserved)
Little brown bat in gloved human hand

Copyright © Kristi DuBois, all rights reserved. Used with permission.

The devastating spread of white-nose syndrome (WNS) in the eastern United States—and more recently infecting a new bat species (Myotis yumanensis) in Washington State (May 2016)—has given a new urgency to bat conservation in the West. As the disease continues to spread, the national parks in its path have stepped up their efforts to learn about and protect native bat populations. It is predicted that WNS will appear in Glacier National Park (Glacier) by 2026 (Rodhouse et al. 2016). Yet at Glacier (Montana), little was known about the park’s bats until a combination of partners, collaborators, and volunteers came together in support of them.

In November 2010, Glacier wildlife biologists received a grant from the Glacier National Park Conservancy that allowed us to initiate a bat inventory and monitoring program at the park. So what did we do first? We headed to the caves! We knew we had caves in the park, but we did not know if their environments were conducive to supporting hibernating bats—or if bats even used them for hibernation. One problem: since Glacier’s caves aren’t generally a focus of management, none of our resources staff had ever been there. Fortunately, there’s a local group that knows Glacier’s caves well. The Bigfork High School Cave Club has mapped the interiors of Glacier’s caves and knows them intimately. So with the help of five teenagers and their teacher in November 2010, we hiked, crawled, and climbed into three caves to install data loggers to record winter temperatures and humidity (fig. 1).

Left: Bigfork High School Cave Club members. Right: Bigfork High School Cave Club member inspects the data logger.
Figure 1. Bigfork High School Cave Club member Brennen Shaw (right) inspects the data logger he helped deploy in one of Glacier’s caves to record temperatures and humidity throughout the winter. (Left) Club members first guided the park biologist to caves in November 2010 to deploy data loggers. Pictured left to right are students Sandy Baker, Keegan Kelso, Eugene Germain, Matt Morgan, Brennen Shaw, and their teacher Hans Bodenhamer.

Glacier National Park/Lisa Bate (2)

This partnership marked the true beginning of Glacier’s bat inventory and monitoring program. Prior to this program, our knowledge about bats in Glacier was nearly nonexistent; no formal surveys had ever been conducted. We had visual records of only four bat species in our wildlife database, one of which was a single, road-killed individual. Of 11 potential species in Glacier, 6 were listed as Montana species of concern (SOC), or potential SOC (MNHP 2010).

We started with temperature and humidity recordings in the caves because we were so excited to start learning anything we could about bats in the park, but were months away from starting bat inventories using mist-netting and acoustic surveys. To accomplish the latter, we partnered with Waterton Lakes National Park in Canada (adjacent to Glacier and the other half of the Waterton-Glacier International Peace Park) to obtain the services of world-renowned bat biologist Cori Lausen. Cori, who has worked with bats for nearly two decades, is an expert in all aspects of bat ecology and survey techniques. We contracted to have her conduct two years’ worth of summer mist-netting and acoustic surveys. Cori, however, was very clear that for the first year to be successful, she needed field assistants with at least some experience in bat surveys.

We didn’t have that experience, so to prepare for Cori’s arrival, we obtained in-kind matching funds from a number of agencies to provide park staff with training, consultation, and equipment. This project would not have been possible without this assistance from the Montana Natural Heritage Program; Montana Fish, Wildlife, and Parks; Bat Conservation International; and of course, the Bigfork High School Cave Club.

Finding the bats

Our main objective was to conduct a basic inventory of bat species in the park. Which species did we have? Which habitats did they occupy? Were they reproducing? What was the overall status of their health? We wanted this baseline information to better inform us of what the potential impact of white-nose syndrome might be, were it detected in Glacier, and to help us to make better decisions about bats in and around the park. Our second objective was to prepare our own staff to take over the bat inventories and initiate the monitoring phase of the program.

Glacier comprises more than 400,000 hectares (1 million acres), and we knew it would take time to conduct a thorough inventory of bats across the park. To sample a wide range of habitats, we adapted the Bat Grid protocol developed by biologists in the Pacific Northwest (Ormsbee 2007), which uses a grid cell of 10 km2 (3.9 mi2) as a sampling unit. Within each grid cell we used both visual and acoustic survey techniques to survey for bats. Mist-netting was our primary, visual technique; acoustic sampling was our secondary technique. Acoustic surveys allowed us to sample habitats not suitable for mist-netting, such as open, burned forests or meadows. It also allowed us to detect bats that typically forage higher aboveground than the nets can reach.

Surveying for bats is not like surveying for any other species: you can’t hear them, you can’t see them. One of the first lessons was learning what the best conditions are for trapping. If a “trap night” coincides with a full moon, expect very few bats. If it is raining, cold, or windy, expect few bats. Bats choose to go into torpor rather than spend precious energy flying around on nights when insects aren’t available. Bats use echolocation—they emit sound waves from their mouths, and use information from the sound waves that bounce back off flying insects—to locate and capture food at night. They also use echolocation to navigate in and around objects. Like humans, however, bats can see at night if there is enough ambient light. So, you have to plan strategically if you want to capture bats in mist-nets.

Cori showed us how to string nets at bends in trails and roads to surprise bats as they flew along these corridors. She would hide, or align, the poles with trees so they could not be seen. She showed us how to set nets over, or near, quiet water bodies (loud water noises interfere with bats’ echolocation calls), and taught us how to tie three nets together to capture the high-flying bat species like the hoary. Wearing chest-high waders to access water nets was normal for trapping bats in Glacier (fig. 2).

Biologists Cori Lausen and Lisa Bate set up a triple-high bat net. Biologists Cori Lausen and Lisa Bate set up a triple-high bat net.

Left image
Figure 2A. Biologists Cori Lausen and Lisa Bate set up a triple-high bat net.
Credit: Credit: Glacier National Park/Courtney Raukar

Right image
Figure 2B. Biologists Cori Lausen and Barb Johnston wear chest waders to deploy a water net in a pond where bats frequently forage.
Credit: Credit: Parks Canada

As we set up each net in the daylight, we would tie them closed with flagging to prevent catching birds and to alert hikers on the trail. We also left signs alerting people to the presence of nets across the trails (fig. 3). Then just as it got dark, we ran around opening the nets all at once. This is called “emergence time” and was always the most hectic time, as the bats emerged from their daytime roosts to come out and feed. If there was a roost nearby, we could get slammed and catch 25–40 bats in a single net in just a few minutes. Things usually calmed down after the first hour and then we would begin the process of checking each net every 4–10 minutes. Any longer, and the bats could chew their way out. On a typical night, we would set up 7–10 nets about 0.8 km (0.5 mi) apart. The constant walking was a good thing, especially on slow nights; it kept us awake and warm.

Left: A nearly invisible mist net is set up across a trail. Right: A signs alerts visitors to a bat survey in progress.
Figure 3. (Left) A nearly invisible mist-net, set up across a trail, is shut and tied with flagging until bat emergence time to prevent “catching” late hikers or nontarget wildlife species. (Right) Monitoring crew used bat survey signs to alert visitors to nets deployed across trails or roads.

Left: Glacier National Park/Courtney Raukar. Right: Glacier National Park/Lisa Bate

Typically, we could not “hear” if a bat was caught in a net. Although little brown bats are notorious for their loud distress calls, most bats would hang quietly until we got there. When working with bats, you quickly learn that a high-quality flashlight is essential. It allows you quickly to determine whether or not a bat is in the net. It also allows you to move confidently at night in moose, mountain lion, and grizzly bear country. One night, while netting in a pond, we heard loud noises coming from multiple directions in the water. The flashlight revealed three huge (larger than our hands) western toads!

When we found a bat in a net we would remove it, place it into a clean cotton bag, and hold it in our jacket or nearby warm vehicle for one hour before processing. The one-hour wait was to give the bat time to defecate so as to obtain an accurate weight; bats can eat 50% of their weight in a foraging bout. For each captured bat we recorded: (1) bat number, (2) net number, (3) time and date of capture, (4) species (Ormsbee 2005), (5) sex, (6) reproductive status, (7) age, (8) tooth class (Christian 1956), (9) weight (g), (10) forearm length (mm), (11) presence or absence of a keel, which is a flap of skin on the tail by each foot (Ormsbee 2005), (12) whether or not a biopsy was taken, (13) whether or not an acoustic sample was taken, and (14) comments on overall health and condition. When finished, we would hold the bat up high until it flew off.

Our first year (2011) of surveys was intense; we trapped 19 of 21 consecutive nights. Cori, seemingly part bat herself, had no problem working all day—setting up mist-nets and detectors, opening and checking nets, removing and processing bats, closing nets, disinfecting everything, and then carrying all the gear back to the trucks for stowage. That first year, we saw a lot of sunrises because we would trap so late into the night. Thereafter, however, we adopted the protocol used by other Montana biologists, and were able to shut the nets down at 1 a.m. This proved to be far more sustainable, allowing us to be in our tents by about 3 a.m. With more sleep, we also found we were able to absorb much more of what Cori taught us.

We moved to a new location each night, trying to sample as many grid cells as possible. On the way to a new site and within the chosen grid cell, we would deploy two to three acoustic detectors to record bat calls for the night. In the first year, we only set up nets within 2 km (1.2 mi) of a road to maximize the number of trap nights. Beyond this distance we had to rely on horse, mule, and boat support because of the weight of the equipment and small size of our crew (three people) (fig. 4). In the second year, however, we began to trap at backcountry sites in hopes of increasing the diversity of bats caught.

Left: Pack stock. Right: Boat
Figure 4. Bat crew receives stock (left) and boat (right) support, respectively, from Glacier biologist John Waller and park ranger Brett Timm, who transport nets and processing gear to backcountry trap sites. Pictured from left to right are Graham Neale, Lisa Bate, Courtney Raukar, and Cori Lausen.

Left: Glacier National Park/Clay Miller. Right: Glacier National Park/Michael Proctor


We have now confirmed the presence of nine bat species in Glacier National Park since we began surveys in 2011: the little brown, long-eared, long-legged, big brown, eastern red, silver-haired, and hoary bat, and California and Yuma myotis (fig. 5). Our detections of the eastern red bat, and the California and Yuma myotis, allowed us to add three new species to Glacier’s mammals list. These detections also expanded the known range for each of these species. All of the species were confirmed through mist-netting except for eastern red bat. Just 4 km (2.5 mi) to the north, however, our acoustic documentation was corroborated with the capture of 13 eastern red bats in Waterton Lakes National Park (Lausen 2012).

A: long-eared bat, B: silver-haired bat, C: California myotis, D: Yuma myotis, E: little brown bat, F: long-legged bat with pup, G: eastern red bat, H: big brown bat, I: hoary bat
Figure 5. Nine bat species have been confirmed in Glacier since surveys began in 2011: (A) long-eared bat (Myotis evotis), (B) silver-haired bat (Lasionycteris noctivagans), (C) California myotis (M. californicus), (D) Yuma myotis (M. yumanensis), (E) little brown bat (M. lucifugus), (F) long-legged bat with pup (M. volans), (G) eastern red bat (Lasiurus borealis), (H) big brown bat (Eptesicus fuscus), and (I) hoary bat (Lasiurus cinereus).

A & B: Glacier National Park (NP)/Courtney Raukar; C: US Geological Survey; D: Copyright ©Kristi Dubois, all rights reserved, used with permission; E: Glacier NP/Courtney Raukar; F: Glacier NP/Cori Lausen; G: Parks Canada; H & I: Glacier NP/Lisa Bate

Six of Glacier’s nine bat species were found throughout the park. Two species—California and Yuma myotis—were only caught and detected west of the Continental Divide, which bisects the park. The eastern red bat was only detected east of the divide. The little brown bat was the most commonly found bat in the park (fig. 6). It is also considered the most common bat in Montana (Foresman 2012). The long-eared was the second most commonly found bat, followed by the hoary bat. The first time we saw and heard a hoary bat, we felt like biologists exploring in a remote country and discovering a new species unknown to the world. We had no idea that such a beautiful animal had been flying over our heads all our lives. None of us in Glacier had ever seen one. Their beautiful coats, large size, and unique hissing and clicking sounds made every mosquito bite we had endured worth it, as this creature was new to us all (fig. 7)!

Percentage of bat species captured and processed during acoustic surveys in Glacier National Park from 2011 to 2016. Data are available in linked file.
Figure 6A. Percentage of bat species captured and processed during acoustic surveys in Glacier National Park from 2011 to 2016 during warm-season months (May through September). Data reflect only those calls that could be identified to species. Data are available in the linked file.
Pie chart showing bat species detected by percentage. Data available in linked table.
Figure 6B. Percentage of bat species detected during acoustic surveys in Glacier National Park from 2011 to 2016 during warm-season months (May through September). Data reflect only those calls that could be identified to species. Data are available in the linked file.
Hoary bat in gloved hand of a biologist
Figure 7. Biologist Cori Lausen spreads the wing of the first hoary bat ever recorded in Glacier.

Glacier National Park/Lisa Bate

In 2013, as planned, all bat inventories were taken over by park staff and volunteers (ages 17 to 65). Since then, we have been able to trap six to eight nights per year, always pushing into new areas while returning to some sites for repeat sampling. Although most volunteers could not handle bats for safety reasons, they were instrumental in helping us set up nets, record data, and check nets for bats. One volunteer, a retired US Forest Service biologist, was the exception: his past experience with mist-netting and handling bats allowed us to set up double the usual number of nets in one evening, which typically resulted in our catching twice as many bats.

Over 61 trapping sessions from 2011 through 2016, we trapped and processed bats at 51 different locations throughout the park (fig. 8). We processed a total of 1,064 individuals, catching about 15 bats per night. This included nights when we did not catch any bats (poor capture success seemed mainly to have been weather-related). None of the bats we processed showed signs of white-nose syndrome; in addition, soil samples from the caves tested negative for the fungus that causes the disease (Northup and Caimi 2014).

We recorded more than 70,000 bat passes (Glacier data files) during warm-season months (May–September) using acoustic detectors (fig. 8). Winter (October–March) acoustic monitoring efforts have detected bat activity at five different park sites, suggesting that bats do hibernate in Glacier. Poor recording quality prevented species identification, but we do know that the park has both low- (for example, big brown or silver-haired bat) and high-frequency (Myotis species) bats. We also now know that at least two of our caves have temperatures and humidity levels conducive to bat hibernation.

Map of Glacier National Park showing locations of (left) mist-nets and (right) acoustic detectors established for bat inventory and monitoring.
Figure 8. Locations of mist-netting (left) and acoustic detector (right) sites established throughout GNP during spring, summer, and fall months for bat inventory and monitoring project from 2011 through 2016 (Glacier National Park, Lisa Bate).

Glacier National Park/Lisa Bate

Changing technology

In April 2015, the northern long-eared myotis was listed federally as threatened under the Endangered Species Act because of risks from white-nose syndrome and wind turbines. Montana is included in the US Fish and Wildlife Service’s range description for northern long-eared bats, but it is unknown if they reside, hibernate in, or migrate through Glacier National Park. We had already confirmed the presence of the eastern red bat, a species not expected in Glacier, and wondered if there could be other anomalies.

Documenting the exact range occupied by a threatened species is critical to its conservation. Species at the edge of their range may be more capable of adapting to climate change and other stressors like white-nose syndrome. To date, we have analyzed more than 70,000 bat call recordings from the park, but poor recording quality has limited the number of definitive classifications. Diagnostic echolocation calls for northern long-eared bats require the use of hardware that can record calls above 100 kHz. Two of the detectors we purchased in 2011 are not capable of recording above this threshold. However, with a grant received in 2016 from the NPS Natural Resource Stewardship and Science Directorate’s Biological Resources Division, we have been able to replace these two obsolete detectors with high-quality ones and microphones to survey for this species. This new equipment is now providing higher-quality acoustic data on the presence, activity, migration, and hibernation patterns of all bat species in the park that are at risk from white-nose syndrome and wind turbines.

Bats in buildings

One important side benefit to this program has been increased efficiency in park operations relative to environmental law compliance activities. As our knowledge about bats in the park grew, so did the number of questions we received from park staff regarding bats. How do we get rid of bats in the attic? Can we re-roof this building in July? More than 900 buildings exist in Glacier National Park. Of the 733 owned by the park, nearly 400 are classified as historic. Most are in need of some repair, restoration, or remodeling, and have multiple entry points for bats. As a result, many of these buildings function as large “bat houses” (fig. 9).

Historic wooden building, the type of which has siding that provides roost sites for bats
Figure 9. Bats roost under siding of historic buildings (A), in bat boxes (B), in attics and barn lofts (C), and under bridges (not pictured) in Glacier. Boy Scouts construct the bat boxes as alternative roost locations. Park facility and integrated pest managers mount the boxes on park buildings that they then attempt to seal to prevent entry by bats.

A, B, and background: Glacier National Park/Lisa Bate. C: Copyright ©Kristy DuBois, all rights reserved, used with permission

The little brown bat is the most strongly associated with human structures in Glacier. It is also a species of concern because of its susceptibility to white-nose syndrome. Before any repair, restoration, or remodeling can begin, a compliance review has to ensure that native species will not be harmed or killed as a result of the work. Until 2015, staff limitations had allowed us to assess only 25 structures for bat use; of those, 16 (64%) were confirmed as roost sites, including maternity roosts. As the compliance list of proposed projects continued to grow, we realized we were not keeping up.

The solution? Forge another partnership. In 2015, a Jerry O’Neal National Park Service Student Stewardship Grant allowed us to hire a Montana State University student to help assess buildings for roosting bats over the course of the summer. The benefits were huge: by the end of summer, 579 buildings (park- and privately owned) had been inspected. Forty-three percent of the inspected buildings were found to contain at least one bat roost, with 451 total roost sites identified. Most roosts were in log cabins or in buildings with wood siding.

Having this information in hand has helped expedite the park’s compliance review process. Now we can query the database to determine if the building had evidence of roosting bats and needs to be rechecked, or if there was no potential for roosting bats (e.g., no loose siding, tin roofs, or small openings), which allows us to move forward with a project. The Montana Natural Heritage Program has used these data as the foundation for their own database on bat roost sites in Montana, which will allow biologists to better assess potential impacts of white-nose syndrome, should it arrive here.

Bats in caves

After three years of winter monitoring, we had confirmed bats overwintering in Glacier National Park (via solar-powered acoustic detectors), but still had to determine if they hibernate in park caves. Additionally, we had collected bat guano for genetic testing to identify bat species, but had found no bats in caves during winter. Results from DNA tests have confirmed that little brown bats use at least one of Glacier’s caves.

Poia Cave, Glacier’s largest cave, is about 1.6 km (1 mi) long, with many hidden cracks and crevices. Visitors are allowed access with a permit. Although few people visit Glacier’s caves, it would only take one person, wearing gear that had been contaminated in a cave where white-nose syndrome was present, to introduce the disease to the park. Knowing when bats were using Glacier’s caves would tell us if they needed increased protection.

With additional funds provided by the Biological Resources Division, we purchased two data roost loggers. In September 2016—again with help from the Bigfork Cave Club and other volunteers—we deployed the data loggers in two park caves. This equipment is capable of monitoring for extended periods, eliminating the need to deploy solar collectors susceptible to avalanche loss and allowing us to avoid dangerous and difficult wintertime bat surveys. We expect these units to monitor for bats for up to six months. In the spring, we will return to the caves and replace the batteries. This will allow us to monitor year-round in the caves to gain a better understanding of when bats are using these natural structures.

Looking to the future we are eager to continue building upon Glacier’s bat inventory and monitoring program with additional support from the Biological Resources Division. Our goals are to complete the “Bats in Buildings” project, expand inventories into additional grid cells, and continue with our long-term acoustic monitoring at select sites in Glacier. Volunteers are eager to help and are already committed. Where else do they get to trek up and over a mountain ridge, belly crawl into a cave to see a magical waterfall, see and hear the hissing and clicking sounds of a hoary bat, and encounter mountain goats, bighorn sheep, grizzly bears, and the rare Canada Lynx along the way!


This project has been made possible with generous grants from the Glacier National Park Conservancy and the NPS Natural Resource Stewardship and Science Directorate’s Biological Resources Division. Additional funds were provided by the Jerry O’Neal National Park Service Student Fellowship Grant. Thanks to our collaborators: Bryce Maxell, with the Montana Natural Heritage Program, and Kristi DuBois, with Montana Fish, Wildlife, and Parks, for technical support, advice, and training. Jason Corbett, with Bat Conservation International, provided advice on cave surveys and mine closures. Thanks to conservation biologist Barb Johnston and retired biologist Cyndi Smith of Waterton Lakes National Park for collaboration and support. Special thanks to retired division chief of Science and Resources, Jack Potter, for recognizing the importance of this program. Thanks to Glacier staff John Waller, Dawn LaFleur, Courtney Raukar, Clay Miller, Susan Clothier, James Waddell, Jack Polzin, Jim Willis, Brett Timm, and Jason Griswold for their support and assistance with the program. Volunteers Gerard Byrd, Karen Chickering, Anne Zavadil, Hans Bodenhamer, and the Bigfork High School Cave Club assisted in placement of roost and data loggers in caves and collection of soil samples. Special thanks to retired biologist Lewis Young, whose continued volunteer support makes it possible to put up twice as many nets every year. Cheyenne Stirling inspected buildings for bat roost sites. And very special thanks to numerous other park staff, volunteers, and family without whose help this program would only partially exist.


Christian, J. 1956. The natural history of a summer aggregation of the big brown bat, Eptesicus fuscus fuscus. American Midland Naturalist 55(1):66–95.

Foresman, K. R. 2012. Mammals of Montana. Mountain Press, Missoula, Montana, USA.

Lausen, C. 2012. Waterton Lakes National Park bat survey. Unpublished Report. Birchdale Ecological, Ltd., Kaslo, British Columbia, Canada. Available from Waterton Lakes National Park, Waterton, Alberta, Canada.

MNHP (Montana Natural Heritage Program). 2010. Montana Field Guides: Bats. Accessed January 2010. Montana Natural Heritage Program, Helena, Montana, USA.

Northup, D., and N. Caimi. 2014. Service-wide investigation of Geomyces destructans (a.k.a. Pseudogymnoascus destructans) in National Park Service caves. Final Report. Prepared under the Rocky Mountains Cooperative Ecosystem Studies Unit, Task Agreement P12AC11090, Cooperative Agreement H2370-09-4001. Northern Arizona University, Flagstaff, Arizona, USA.

Ormsbee, P. 2005. Key to Idaho, Montana, and South Dakota bats. Unpublished document. US Forest Service, Willamette National Forest, Eugene, Oregon, USA. Available at

———. 2007. Bat grid draft protocol. Unpublished document. Appendix E in J. Kesling, C. Abel, and L. Schwabe, primary authors. 2008. Malheur River wildlife mitigation project (BPA project 200002700): 2008 annual report. Bonneville Power Administration, Portland, Oregon, USA. Available from

Rodhouse, T. J., T. E. Philippi, W. B. Monahan, and K. T. Castle. 2016. A macroecological perspective on strategic bat conservation in the U.S. National Park Service. Ecosphere 7(11):e01576. doi:10.1002/ecs2.1576.

About the author

Lisa Bate is a wildlife biologist at Glacier National Park, West Glacier, Montana. She can be reached at (406) 888-7833 and e-mail us.

Glacier National Park

Last updated: March 21, 2021