We could be looking at extirpation.
In the hidden depths of a Jasper National Park cave, a fungal disease two decades in the making has arrived ahead of every expectation, leaving 69 dead bats where history suggested there should be three. White-nose syndrome, which has reshaped the ecological fabric of eastern North America since 2006, now threatens the Rocky Mountain's small and fragile bat colonies with a particular cruelty: what larger populations absorbed as catastrophe, smaller ones may not survive at all. The arrival is a reminder that isolation is not immunity, and that the mountains, for all their grandeur, cannot hold back what travels on the wings of time and human movement.
- A spring survey that should have been routine turned alarming when researchers found 69 dead bats — more than six times the highest count ever recorded at the site.
- The fungus does not simply kill; it unravels hibernation itself, forcing bats to burn through fat reserves they cannot replenish before spring, making survival a matter of arithmetic that small colonies cannot win.
- Jasper's bat population numbers in the hundreds, not the thousands, meaning the same mortality rates that eastern colonies absorbed and endured could here mean total regional disappearance — extirpation, in the clinical language of the biologists who fear it.
- Parks Canada and its partners are deploying probiotic treatments at summer maternity roosts, betting that beneficial bacteria spread colony-wide can blunt the worst of the fungal damage before next winter arrives.
- Researchers are racing to find every bat colony they can, asking the public to report bats in attics and buildings, knowing that each new site identified is another place where intervention is still possible.
A cave somewhere in Jasper National Park — its location kept secret to protect what shelters inside — holds the only known bat hibernation site in the entire park. When researchers entered it this past March, they found what they had long feared but hoped would come later: white-nose syndrome, the fungal disease that has devastated bat populations across North America since first appearing in New York State in 2006, had reached the Rocky Mountains.
Parks Canada wildlife biologist Nina Veselka had known the disease was coming. Alberta detected it in 2022, and visible symptoms appeared on bats elsewhere in the province by 2024. Researchers had hoped the mountains might slow its advance. The spring survey ended that hope. Under ultraviolet light, infections glowed across the wings of hibernating bats. "It was pretty severe infection," Veselka said.
The numbers told the starkest part of the story. The cave's total bat count — around 615 — was relatively stable compared to the previous year. But dead bats numbered 69, against a historical average of roughly 3 and a previous single-survey record of 11. "That's a huge jump," Veselka said. The disease disrupts hibernation, causing bats to exhaust their fat reserves before spring. In eastern caves holding tens of thousands of animals, populations have survived catastrophic losses. Jasper's colonies are far smaller, and the math is unforgiving. Without intervention, some species could vanish from the region entirely.
The response is already underway. Parks Canada, the Wildlife Conservation Society Canada, and Alberta Environment and Protected Areas are applying probiotic treatments to maternity roosts — the summer nursery sites where females raise their young — allowing beneficial bacteria to spread through colonies as bats return from hibernation. Treating the hibernation cave directly would disturb the animals at their most vulnerable, so the maternity roosts offer a less invasive path. Veselka is measured about what the treatment can achieve. "This is not some miracle solution," she said, "but it is better than stepping back and doing nothing."
Researchers are also asking the public to report bat colonies found in buildings and attics, hoping to expand the number of sites where treatment can be deployed. Human activity has contributed to the disease's spread — scientists believe the fungus arrived from Europe on contaminated clothing and equipment — and every unnecessary cave visit risks carrying spores further. For now, the cave in the mountains holds the question that no one can yet answer: whether the measures being taken today will be enough to keep Jasper's bats from disappearing altogether.
A cave in Jasper National Park, location kept secret to protect what lives inside, holds the only known hibernation site for bats in the entire park. In March, researchers entered that cave and found something they had been dreading for years: white-nose syndrome had arrived. The fungal disease, which has swept across North America since 2006, killing 90 to 98 percent of bat populations in some eastern regions, was now confirmed in the Rocky Mountains. Parks Canada wildlife biologist Nina Veselka had expected it would come eventually. She did not expect it to arrive so quickly.
The fungus first appeared in New York State two decades ago and spent years moving westward. Alberta detected it in 2022. By 2024, visible symptoms were showing up on bats elsewhere in the province. Researchers had hoped the mountains might slow its advance, that elevation and isolation might buy time. The spring survey proved otherwise. When Veselka and her team examined bats in the cave using ultraviolet light, the infections glowed across their wings. "It was pretty severe infection," she said. Some animals bore the white fungal growth on their bodies that gives the disease its name.
What alarmed researchers most was not just the presence of the fungus but what it was doing. The cave held 615 bats during this year's survey, compared to roughly 650 the previous year—a relatively stable count. But the dead bats told a different story. Since Parks Canada began monitoring the site in 2010, the highest number of dead bats found in a single survey had been 11. In recent years, that number typically hovered around 3. This spring, researchers found 69 dead bats. "That's a huge jump," Veselka said.
The disease works by disrupting the hibernation process itself. Infected bats cannot maintain their winter torpor properly and burn through the fat reserves they need to survive until spring arrives. In the eastern United States and Canada, where hibernation caves sometimes contain tens of thousands of bats, populations have absorbed catastrophic losses and persisted. Jasper's colonies are different. They are small. If the same die-off rates occur here, the math becomes unforgiving. "If we're starting with a much smaller population size and seeing the same die-off, the impacts are so much more profound," Veselka said. Without intervention, some bat species could vanish from the region entirely. She used the word "extirpation."
Parks Canada and its partners have begun fighting back. They are applying a probiotic treatment designed to reduce the severity of fungal infections. Rather than treating the hibernation cave directly—which would disturb the bats at their most vulnerable—researchers are applying the treatment to maternity roosts, the summer nursery sites where female bats gather to raise their young. As bats return from hibernation and occupy these sites, the beneficial bacteria can spread through the colony. The work is being done in collaboration with the Wildlife Conservation Society Canada and Alberta Environment and Protected Areas. Veselka is careful not to oversell what the probiotic can do. "This is not some miracle solution to rescue the entire population," she said. "But it is better than stepping back and doing nothing."
Parks Canada is also asking residents to report any bat colonies they find in buildings, attics, or other structures. The more sites researchers can identify, the more places they can deploy treatment. The public is being urged to stay out of caves and avoid disturbing bats. Human activity has played a role in spreading white-nose syndrome across North America. Scientists believe people inadvertently brought the fungus from Europe, where bats have lived with it for thousands of years. Today, contaminated clothing, footwear, and equipment can carry fungal spores between cave systems. Every unnecessary visit to a cave risks spreading the disease further.
Despite the grim outlook, Veselka sees an opportunity in the crisis. Bats are often misunderstood, she said. All of Alberta's bat species feed on insects, consuming thousands each night and controlling mosquitoes and agricultural pests. They are the only mammals capable of true powered flight. "They're pretty cool," she said. For now, researchers will continue monitoring Jasper's bats closely, hoping the measures being taken today can prevent the worst outcomes tomorrow. The cave in the mountains holds the answer to whether that hope is enough.
Notable Quotes
It's taken 20 years to get here, but it was inevitable. It was a little surprising how quickly it jumped into the mountains.— Nina Veselka, Parks Canada wildlife biologist
This is not some miracle solution to rescue the entire population. But it is better than stepping back and doing nothing.— Nina Veselka, Parks Canada wildlife biologist
The Hearth Conversation Another angle on the story
Why did this disease take 20 years to reach Jasper when it's been spreading across North America since 2006?
The fungus moved west gradually, reaching Alberta in 2022. Researchers thought the mountains might slow it further, but it jumped into the high country faster than expected. Geography isn't as much of a barrier as they hoped.
What exactly does white-nose syndrome do to a bat?
It disrupts hibernation. Bats can't maintain their winter sleep properly, so they wake up and burn through their fat reserves before spring arrives. By the time they need that energy to survive, it's gone.
The jump from 3 dead bats to 69 in one year—is that the disease getting worse, or just now showing up?
It's the disease showing up and hitting hard immediately. The population count stayed stable, but mortality spiked. That's the fungus at work.
Why is Jasper's situation worse than what happened in the East?
Eastern hibernation caves hold thousands or tens of thousands of bats. Even after losing 90 percent, enough survive to rebuild. Jasper's colonies are tiny. Lose 90 percent of a small population and you might lose the species entirely from the region.
Can the probiotic treatment actually save these bats?
It's not a cure. It might reduce infection severity enough that more bats survive hibernation. That's the best realistic hope right now.
Why are researchers asking people to report bat colonies in buildings?
Every maternity roost they find is another place they can apply treatment. The more sites they can reach, the better the chances of the bacteria spreading through colonies before winter.