Wildlife

The race to save B.C.’s bats

As a deadly disease threatens the species’ existence, bat conservationists rush to find an antidote before it’s too late

  • Published Oct 31, 2024
  • Updated Nov 18
  • 4,078 words
  • 17 minutes
  • By Hanna Hett
  • with photography by Jared Hobbs
A pallid bat shown in flight. (Photo: Jared Hobbs)
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In the gloom of a forest just after sunset, conservation researchers Aimee Mitchell and Chris Currie stand beside a bat box (an artificial roost bats sleep in), dressed in surgical masks and plastic gloves. They’re in Alice Lake Provincial Park, a campground 15 minutes north of Squamish, B.C.

The sounds of scratching, shuffling and chirping from inside the roost let Mitchell know that the bats are awake and preparing to take flight on their nightly hunt for insects. However, the emerging bats are confronted by a “harp trap” (two sets of translucent strings made from fishing line and arranged like the strings of a harp). As the animals attempt to maneuver through these strings, tucking their wings or turning sideways, most of them hit the first set of fishing lines mid-air and fall into a plastic bag the biologists have set up below. The few that do make it through hit the second set of strings and fall into the basket with the rest.

Once about 40 to 50 bats are entrapped, Mitchell gently picks up her first of the night. In her hands is either a little brown bat or a Yuma myotis — the two species are nearly impossible to distinguish by eye. The bat’s mouth gapes open as it bares its small teeth. Mitchell knows the bat is screaming at her in a frequency the human ear can’t hear. The bat tries to bite her, too, but the seasoned conservationist remains unfazed. She puts it into its own cloth bag, draws a pull string to close it, and leaves the creature to calm down.

The bats are tiny. They weigh between five and nine grams (about the weight of a quarter) and are around the length of a credit card. When they open their wings, however, they quickly become much more intimidating. In this position, they can span the length of a grade-school ruler. Their wing bones resemble human finger bones (if human fingers were so long they dangled to the ground) and are webbed with thin but strong skin. They have fuzzy brown fur, black ears that stick up in triangles like a pig’s and a pointed face, and their eyes are black and beady.

A Townsend big-eared bat photographed in B.C. (Photo: Jared Hobbs)
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Mitchell and Currie will work until four or five a.m. underneath a star-lit sky, surrounded by tall evergreen and deciduous trees. In the light from their headlamps, they can see bats swooping up and down around them, hunting the mosquitoes that have gathered to feed on the researchers. For each bat, they must swab its wings, determine its reproductive status, weight, and wing measurement and use a needle to insert a tracker in its back (if it doesn’t already have one).

This process is a nuisance to the bats (and causes many sleepless nights for Mitchell and Currie) but this is the frontline to save bats from mass death. The swabs the pair collects are sent to a lab, where they are tested for the presence of a probiotic cocktail of naturally occurring bacteria that can help prevent disease. This probiotic has the potential to stave off white-nose syndrome, an illness that has decimated bat populations east of the Rocky Mountains. The syndrome has quickly spread further and further west and is now within a few hundred kilometres of B.C.’s border — if it isn’t already here.


In the winter of 2007, biologists went into a cave in New York State, planning to complete a normal population survey of hibernating bats. Instead, they discovered piles of them dead on the ground. Those still living had a scabby white substance (the fungus that causes white-nose syndrome) covering their faces, ears, and wings. In nearby hibernating sites, more piles of dead bats were found. Scientists later learned that the first case of the disease had likely originated in New York in 2006. In the 18 years since, the syndrome has steadily spread across North America. In some places, killing 90 to 100 per cent of the bat population. White-nose syndrome has now been found in nine Canadian provinces (as far west as Alberta ) and 40 U.S. states. 

Cori Lausen, the director of bat conservation for the Wildlife Conservation Society of Canada, had been watching the disease cross the continent from her home in the B.C.’s Kootenay region. In 2015, she started assembling a team to start searching for some sort of antidote to the fungus. It seemed like only a matter of time before the disease crossed over the Rocky Mountains. She never imagined that the danger would instead come from the south.

“It was hard to believe. It was hard to fathom,” said Lausen. “It made this giant leap.”

Genetic testing later confirmed that the syndrome had come from Kentucky in the U.S. This cross-country move was likely human-caused. For example, an infected bat might have hitched a ride on a transport truck across the U.S., carrying the disease into unchartered territories — right to B.C.’s doorstep.

“We have no clue what’s going to happen in the West,” said Lausen.


No one knows how many bats have died from white-nose syndrome. In 2012, researchers looked at the regular colony counts in Eastern U.S. and estimated that the number was about six to eight million bats but as the disease has spread across the continent and into places where baseline population numbers aren’t known, they have been unable to estimate the numbers in the years since.

A long-eared myotis bat. (Photo: Jared Hobbs)
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This disease is caused by a fungus that evolved with bat populations in Asia and Europe and lives off living bat tissue. Scientists believe that humans inadvertently brought the fungus to North America. An unsuspecting bat might have traversed the Atlantic on gear or equipment, or fungus spores might have attached to gear or tourists. It then found a home in North American bats, who, unlike those in Eurasia, have not evolved to survive it.

The syndrome hits bats when they are at their most vulnerable. Once their food supply of insects dwindles in the fall, bats find cool, damp places to settle down and hibernate for the winter. Their heart rate slows, their body temperature drops substantially (from 37 to 41 to one to 16 degrees Celsius) and their immune systems grind to a near stop. This is normally an evolutionary advantage — a way for bats to expend much less energy when food supplies are scarce. But if they have the fungus on them, it spreads over the nearly inert animals’ wings, faces, and tails. They awake from hibernation to groom it off, restarting their immune system, then return to a hibernating state. The fungus regrows.

“It’s literally a war. Bat versus fungus,” said Lausen. “And unfortunately, they just burn through all their fat before the end of the winter. Most of them simply die of starvation.”

The bats that survive the winter often sustain significant wing damage. The fungus eats away their tissues, leaving behind scars and gaping holes that sometimes inhibit their ability to fly. Those who can still fly could die from moisture loss, throwing off the animal’s salt balance. Fungal damage can also cause physiological imbalances, disrupting things like their ability to regulate body temperature. Sometimes, as the bats come out of hibernation in the spring, their infected tissues become inflamed — a normal immune response, but one that can kill the already weakened bats.

Many people fear bats or believe they’re creepy carriers of disease. Lausen was intrigued by this perception, even as a child. She has memories of hiding in the bathroom with her mom and sister, while her dad killed a bat that had somehow flown into their kitchen.“I remember thinking, ‘Why are adults so scared of these tiny little fuzzy cute creatures?’”

Years later, when she was attending university to become a school teacher, one of her professors asked her to spend a summer researching, and something (perhaps a flashback to her childhood) compelled her to choose bats. She was immediately fascinated by the small, flying mammals. 

Bats can live upwards of 30 years, a unique feat for such a small mammal. They reproduce slowly, having just one pup per year that has only a 50 per cent chance of reaching maturity. Even as adults, how they survive fascinates researchers. Their diet of insects is so calorically low that scientists say they should have to eat around the clock to stay alive. Instead, they survive by only eating at nighttime with behavioural tricks to burn fewer calories. After graduation, Lausen taught at a high school for five years, but eventually found her way back to bats.

They are underrated pest controllers and nutrient recyclers.

Scientists now know that bats (despite their unfavourable reputation) are ecologically important animals. They are underrated pest controllers and nutrient recyclers. Their night-long insect hunting escapades are particularly helpful for the forestry and agriculture industries, saving them large sums of money on pesticides; research from 2011 estimates that bats provide a value of nearly U.S. $23 billion to American farmers alone. A paper published this year suggests that bat die-offs caused some farmers to increase insecticide use by 30 per cent. The economic value of bats in B.C. hasn’t been studied, but it is home to 18 bat species. This is by far the highest number of any province — Ontario and Saskatchewan are tied for second place with about eight apiece, while the Yukon reportedly has five.

Each of B.C.’s bats has a unique role in the ecosystem, consuming different kinds of insects in different habitats. Some of B.C.’s long-eared species fly around forests, where they pick insects right off vegetation — an unusual behaviour for bats, who typically hunt insects mid-air. The long ears help control harmful insects like the spruce budworm, which can kill trees if its population is left unchecked.

“We’ve got this really complex ecosystem,” said Lausen of B.C. “That complex ecosystem really requires a much bigger diversity of bats to keep it balanced.”

Each bat species, whether or not it benefits humans, has inherent value in and of itself, as a unique living thing. They have also long been culturally important symbols of the night and our own darker natures. Bat symbols are engraved in Egyptian tombs from 2000 BC. William Shakespeare wrote in Macbeth that the “wool of a bat” would go into a witch’s cauldron. Dracula transforms himself into a bat. And, of course, George Clooney, Christian Bale, Ben Affleck, and Robert Pattinson have all starred in films as a vigilante who dresses up as a bat to save Gotham City.

We might miss them if they were gone.


When Lausen started looking for a way to save B.C. bats nearly a decade ago, she first teamed up with Naowarat Cheeptham, a cave microbiologist in Kamloops, B.C. In the confines of Cheeptham’s lab at Thompson Rivers University, she and her students got to work looking for what they called a “biocontrol agent” (a naturally occurring substance that could kill the fungus). Her team swabbed everything they could think of: mushrooms, honey, trees, water, sewage, and different kinds of soil. They then took these swabs, isolated the bacteria off them, grew the bacteria, and then tested them against the white-nose fungus in Petri dishes to see if something could kill it.

Nothing was working.

A long-legged myotis. (Photo: Jared Hobbs)
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In 2016, Cheeptham learned that one of her colleagues in Thailand was researching propolis, a substance with anti-microbial properties found in beeswax. Inspired, she and her research team gathered beeswax and tested it against the fungus. It worked.

“Then we went, ‘Wait a minute, we really don’t feel like we should be putting something so unusual on bats,’” said Lausen.

Propolis, they realized, might be able to kill the fungus, but they didn’t know how it might affect other native bacteria and fungus. At this point, they were well into their second year of research, and white-nose syndrome had just been discovered in Washington state. Cheeptham was starting to feel panicked while Lausen was having trouble sleeping.

Shortly after, Cheeptham learned that a friend in New Mexico had found that some bats have naturally occurring bacteria on their skin that kills the fungus. She realized they could look for the same in B.C. Bats, just like humans, have numerous microorganisms on their bodies — maybe what would save them was already on their skin. Lausen calls it a “Robin Hood” approach. They could take helpful bacteria that just a few of B.C.’s bats might have and spread it to the rest. “Sort of like taking from the rich and giving to the poor,” said Lausen.

Lausen, her team of volunteers and bat biologists were already catching and swabbing bats for data collection. She sent Cheeptham more than 250 swabs from 13 species of bats — mostly from B.C., but some from Alberta and Saskatchewan. Cheeptham and her students then took these swabs, dunked them in Petri dishes and let the bacteria grow. They isolated more than 1,300 different bacteria. Now, every single one needed to be tested against the fungus to see if it could kill it.

They grew the fungus on large trays and placed about 80 different bacteria on each tray before putting them in an incubator to grow for about a week or two. If, when they checked it, there were “killing zones” where the fungus hadn’t grown around the bacteria, they would know they were one step closer to their goal.

“It’s huge work. It’s very tedious,” said Cheeptham.

Four months into this process, when they had narrowed it down to about 20 promising bacteria, they looped in Jianping Xu, a mycologist at McMaster University. In his lab in Hamilton, ON, he and his students used a similar method to test different combinations of the bacteria that had resisted the white-nose fungus. About two months later (halfway through 2017) they found a mix of four of them with a synergistic effect, meaning they work better together. They finally had a probiotic treatment for white-nose syndrome made of bacteria from bats’ wings.

But a challenge still lay ahead of them. “How are we going to apply these bacteria onto the bats?” said Cheeptham.


Nicholas Fontaine, a Thompson Rivers University student, pulls on a white hazmat suit, a shower cap, boot covers, and disposable gloves before entering a large, plastic carport — the kind people might buy from places like Canadian Tire. Fontaine is completing his graduate research under the supervision of Cheeptham. The carport’s current purpose is to serve as a bat enclosure. It’s daytime, so the 10 Yuma myotis bats it holds are huddled together, sleeping in their bat boxes. Fontaine fills up muffin tins with mealworms, which he taught them to eat, and tops up their water dishes. 

A fringed myotis. (Photo: Jared Hobbs)
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Before entering the second enclosure, Fontaine changes into fresh gear to avoid any contamination. Here, the real work awaits. Another 10 bats live here, who not only need to be fed and watered but also have their wings swabbed. This group of bats is being trialled with the probiotic cocktail that Cheeptham and Xu developed. It’s Fontaine’s job to see if the probiotic can survive on living bats.

For the summers of 2018 and 2019, Fontaine lived and breathed this trial, driving to and from his home in Kamloops and the B.C. Wildlife Park on the outskirts of town each day to care for the animals.

“It was a lot of responsibility,” he says. “I didn’t want to let anyone down.”

To apply the probiotic onto bats, the team eventually settled on the idea of mixing the bacteria into sterile water or combining freeze-dried probiotics with clay and spraying it into bat boxes. Once it is in the bat boxes, it transfers onto the bats themselves, merging with the bacteria that naturally live on their skin. Then, Fontaine (along with the team’s advising veterinarians) could monitor and test the bats to ensure that the probiotic was safe for the animals. No adverse effects were found.

In September 2019, Fontaine began testing the probiotic on hibernating bats. The research team didn’t have the money to purchase a specialized hibernation fridge, so Cheeptham went to Costco and bought a wine cooler. Setting its temperature to five degrees Celsius and its humidity at 90 per cent, Fontaine installed a camera so he could keep an eye on his test subjects, then put several Yuma myotis in the fridge. He then slowly took away their food, forcing the bats’ instincts to kick in. “Like, ‘Hey, I can’t scavenge any more food. I need to hibernate,’” said Fontaine. 

It turned out that the cool and moist environment that bats hibernate in was also the environment in which the probiotic thrived. Not only did it stay on their wings, but it also reproduced. This meant that if bats have the probiotic on their bodies going into hibernation, even if it was just a small amount, it has the potential to increase. The probiotic was showing promise as a defence against white-nose syndrome.

It was time to see if it would work in the wild.


At the same time that Fontaine was carrying out his trials, Leah Rensel, a grad student at the University of British Columbia Okanagan, was establishing baseline data for five little brown bat and Yuma myotis communities in the Greater Vancouver area, including at Alice Lake Provincial Park. In August 2019, the team sprayed their first maternity roost (a bat box where bats spend the summers raising their young) with the probiotic. The following year, COVID-19 caused a snag in their field work, because they needed to ensure that they didn’t introduce the virus to B.C.’s bats. But the project was too urgent to stall for too long.

“We just kept thinking, ‘At any moment, white-nose syndrome fungus could show up in the province,’” said Lausen. When going into the field, bat biologists masked up, took COVID antigen tests, and could no longer carpool to the field sites. A few months later than they would have liked, they sprayed all five sites with the probiotic.

Work was back on track the following year. Each spring since, the team has sprayed three of the five (two are control sites) summertime colonies’ roosts with the probiotic. Every year, the swabs the researchers (including Mithcell and Currie) collected have confirmed that bats have flown off to their winter hibernating spots with it on their bodies. These same bats have not yet tested positive for white-nose syndrome, nor has the fungus been found in these sites. 

In the east of North America, Lausen said that white-nose followed a predictable pattern. “You get the fungus. Within two years, you’ve got the disease. And within another year, you’ve got a mass die-off. That’s not at all the pattern we’re seeing here,” she said.

But this isn’t yet a cause for celebration.


The threat of the fungus has made it clear how little is known about bats. Before white-nose hit North America, bat populations were stable. With their survival taken for granted, little funding was available to research these animals. As a result, basic knowledge about bats, such as how the same species vary across ecosystems, why their immune system staves off most viruses, or even where they roost in trees is poorly known. If humans hope to understand how these animals are affected by anthropogenic changes beyond the white-nose crisis, says Lausen, this knowledge is needed.

Bats face a multitude of threats: forestry clears away important bat habitats, wind turbines built in migratory pathways have put some species at serious risk and increased pesticide use and insect decline is also a substantial—though not yet measurable—threat.

The threat of the fungus has made it clear how little is known about bats.

“The irony of the way our system works is that they start throwing money at something once it becomes rare. But once it becomes rare, it’s so much harder to study. And we’re going to learn a lot less about it than we could have while it was still common,” said Lausen.

The lack of knowledge about western bats also makes monitoring the disease much more challenging. While it seems like good news that white-nose syndrome hasn’t been detected in B.C., and it might seem like the disease is moving more slowly in the West than it did in the East, Lausen says that they might simply be failing to detect the disease. They don’t know where most bats hibernate in the winter, so they “don’t have the advantage of going into caves and seeing big piles of dead bats,” she said.

A spotted bat. (Photo: Jared Hobbs)
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Meanwhile, the fungus is creeping closer and closer. In 2022, it was found in Alberta In 2023, it was confirmed in eastern B.C.—far away from where the probiotic is being trialled. The syndrome (what kills bats) has yet to have been detected in B.C. but was confirmed on two little brown bats in Alberta in May of this year. 

“Something is just weird about the way the fungus is affecting bats in the West,” said Lausen.

Because in Washington state bats are dying.


Abby Tobin is dressed in a full set of protective gear, including a N-95 mask, face shield, and hooded Tyvek gloves. She stands at the back of her truck, with four 50-millimetre vials set out in front of her, each one containing a bacterium from the probiotic. Tobin pipettes a small amount of each into a large spray bottle (similar to those used for pesticides) with sterile water.

She then enters a house and walks up a steep set of stairs to an attic which a nature-loving family lets a colony of bats roost in. Tobin searches for signs of bats (either guano or stains on the walls) and mists the roost lightly with her spray bottle. It’s March 2024, so the 150 to 200 bats that spend the spring and summer here have yet to return from their winter hibernation. 

Tobin is a several-hour drive and an international border away from the probiotic trial sites in B.C. She’s the white-nose syndrome coordinator for the Washington Department of Fish and Wildlife, a position that was almost immediately created after the disease was discovered in the state in 2016.

When she learned about Lausen and the B.C. team’s probiotic, she was eager to test it. “We’re the only western state really with white nose,” she said. “So, we’re really in a position that we’re like, ‘we really should be doing something.’” Tobin is also trialling a U.S.-developed white-nose vaccine at different sites in the state.

There have been two known white-nose mortality events in Washington state the most recent in winter 2024. Bats started showing up to their springtime roosts early, in February, with no fat and dehydrated, crinkly wings — sure signs of the disease. In a month-and-a-half span, there have been around 50 dead bats. Since the syndrome was discovered in the state, there have been over 230 cases. “But those are just the ones that we have found,” said Tobin, adding that they have seen some bat colonies decline substantially, including one near Seattle that dropped from 1000 to 15, but that they aren’t yet sure what the cause is. 

In 2023, after a few years of scoping out potential sites and collecting baseline data, Tobin started trialling the probiotic at three different roosts in the state. There are also three control sites to compare the difference. 

Already, results from the trial are looking promising. Tobin sent this year’s Washington bat swabs to Xu’s lab at McMaster for testing. What they found signals that the probiotic is working. The more of it found on the batwing, the less white-nose fungus. 

It will take another couple of years before they know for certain that the probiotic saves bats. But back in B.C., Lausen is excited about these results and the possibility it gives the creatures she’s devoted her career to. 

No one knows how white-nose syndrome is affecting western bats. No one knows what will be lost if they are gone. And no one knows what we have lost with the millions of bats that have already died. But now there’s hope.

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