Researchers delve into cracks and crevices to learn about bats that roost on cliffs
by Kristen Pope
Dangling off a cliff 300 feet above the ground, Zac Warren peers into a dark crevice. Wearing an N95 respirator mask and gloves, he carefully reaches in and gently swabs a roosting bat before rappelling back down to the valley floor.
Warren is Bat Conservation International’s Vertical Habitat Specialist, and he is performing White-nose Syndrome surveillance in Utah’s Zion National Park. He will send the samples he collects to a lab to see if Zion’s bats are affected by the fungus that causes the deadly bat disease. Collecting such samples is just one of his many duties as he studies the park’s crevice- and cliff-dwelling bats, part of a collaborative effort between Bat Conservation International and the National Park Service.
While cave- and structure- dwelling bats receive a lot of attention, a bat can make its roost even in tiny cliffside rock openings. These cliffside abodes can have advantages, such as providing a great takeoff point from which a bat can swoop down hundreds of feet coming out of its roost. Bats look for microhabitat features that will provide a good roost, from the right temperatures to sources of water to lure in insects. Species that live on cliffs generally can also be found in other types of habitats, like caves, as long as the environmental conditions are right. Sometimes, cliff roosts aren’t all that different from caves—while many are tiny, others can be quite large.
“Cracks and crevices can extend very far back into cliff surfaces and mimic the thermostability of an underground feature,” says Jason Corbett, Bat Conservation International’s Habitat Protection and Restoration Director.
A day in the life of a vertical habitat specialist
To study cliff-dwelling bats, Warren spends his days traveling to remote rock formations, climbing rock faces, trekking miles, and rappelling from cliffs during the winter field season—all to monitor and conserve bats that dwell in these unique ecosystems.
Based in Springdale, Utah, Warren has worked for Bat Conservation International since 2019. A rock climber since 2008, he’s worked in the wildlife field since 2011, and has a bachelor’s degree in wildlife biology and a master’s degree in applied ecology.
Warren’s days start before dawn, when he meets up with two volunteer climbers each day. These experienced climbers assist with tasks like carrying gear, collecting data, and even initiating rescues if necessary.
Each morning, the team goes over their plan for the day, looking at coordinates and photos, assessing the route’s aspects and difficulty, and sharing any other site information they may have before conducting a risk assessment as a group. Once they are finished and everyone is on board with the day’s agenda, Warren files their travel plan with park dispatch, and they head out shortly after dawn.
“Depending on the objective, it could take us six, eight, 14 hours,” Warren says. “We could be getting out well after dark. Some areas require us to hike in eight miles, other spots are right off the road.”
Some areas require multi-pitch climbs up 600-foot-tall rock chimneys while others are easier to access from above by rappelling down. “I use climbing as a tool to get into an area that I want to survey,” Warren says. “If we can get access to it from above, we’re going to come in from above if that’s the easiest, safest way.”
Due to COVID-19 precautions, climbers wear N95 respirators when they might be within 6 feet of a bat. The climbers are also bundled up against the cold, since field season usually lasts from November to February.
“We’re out there on a lot of days climbers are not because it’s 20 degrees and overcast,” Warren says. “We’re also going into super deep, dark chimneys that are dirty and dusty.”
He says it feels surreal and that the deep crevices can resemble caves. Sometimes, he’ll enter a crevice with fine sand and see only woodrat footprints, knowing he is likely the first human to enter the space.
When his team finds bats, they will document the roost site characteristics, collect swab samples, and do everything they can to minimize disturbance. The more sites they find, the more they learn about the characteristics bats prefer.
“It helps us to predict where they are more likely to occur on the landscape,” Warren says. “The more surveillance we do on these bats, the better we can hone in on where they roost, and the easier it is to be able to find and manage them.”
At the end of the day, the team returns to the office to drop off gear and select sites for the next day. By day’s end, Warren is often exhausted—but it’s not the physical aspect of his work that wears him out.
“My brain is always working at 100 miles per hour because it’s not just climbing, but also surveying for bats,” Warren says. “I’m thinking about it ecologically, looking for roosting bats while also working in an environment where I constantly need to be aware of my surroundings.”
He says he’s constantly thinking about where the rope is running, hazards that might be present—such as if a “false floor” at the bottom of a feature could cave in—and he’s mindful to always take proper precautions around bats. His crew’s well-being is always on his mind, as is the clock, and he’s constantly aware of the amount of daylight left and when the crew will need to turn around to get down safely.
“You can be really mentally fried at the end of the day because of such hyperawareness,” Corbett says. “Most people don’t walk around with a 360-degree sense of awareness every second.”
Long days out collecting data are preceded by months of planning and preparation. Before the field season, Warren creates a list of sites he will survey throughout the season, working with volunteers to document cliff features and collecting observations about where bats might roost. He also conducts driving transects, maps species distribution, performs outreach, recruits volunteers, and works on the Zion Search and Rescue team, where he is now an instructor. “It keeps me in that operational mindset throughout the year,” Warren says.
Unveiling cliffside mysteries
The Zion project is likely to expand to other Utah parks, and additional Bat Conservation International cliff ecology projects are currently in the planning stages. Previous work has included collaborations with Canyon de Chelly National Monument and Glen Canyon National Recreation Area.
Cliff ecology isn’t as well-studied and understood as some other fields, but Corbett points out microhabitat features, like small seeps or spring-like features, can lure in insects, creating concentrated patches of food for bats and increasing foraging capacity.
“It’s a bit of a new frontier, which might sound like some sort of a stretch to folks,” Corbett says. “Why would you care about a little watery stain smeared somewhere? But when we’re looking at a cliff as an ecosystem, we’re starting to put those pieces together.”
Corbett emphasizes the importance of gathering data and unraveling these mysteries as soon as possible, especially in light of threats like White-nose Syndrome and climate change.
“We have to look at one of the last frontiers of bat ecology in the U.S., and the time to act on gathering information and trying to be proactive about conservation is right now,” Corbett says.
Cliff- and Crevice-Dwelling Bats
Bat Conservation International Vertical Habitat Specialist Zac Warren and his team find a number of different bat species high in cliffside cracks and crevices. Sometimes, they will find large colonies of more than 100 Big Free-tailed Bats (Nyctinomops macrotis) or smaller clusters of Canyon Bats (Parastrellus hesperus). Other species they find include California Myotis (Myotis californicus), Mexican Free-tailed Bats (Tadarida brasiliensis), Pallid Bats (Antrozous pallidus), Silver-haired Bats (Lasionycteris noctivagans), and Townsend’s Big-eared Bats (Corynorhinus townsendii).
Climbing Community Aids Scientific Research
Volunteers from the climbing community are helping to protect Zion National Park’s cliffside bat populations. The Zion Big Wall Bats program encourages climbers to report any bat sightings, so the cliff ecology team can investigate. Bat Conservation International Vertical Habitat Specialist Zac Warren also conducts outreach and works with local climbing groups, like the Zion Climbing Coalition, to find people who want to help. Volunteers are all experienced climbers, including park rangers, botanists, recreational climbers, and guides.
Warren says climbers feel a draw to give back and use their skills to assist with conservation work. “Climbers love the areas in which they’re climbing, and that causes them to be very conservation-focused,” Warren says.