Wing and a prayer: how probiotics might save bat species from a killer fungus

Bats Face Existential Threat as Killer Fungus Reaches Arctic Hibernation Grounds

Wanderstayfinder.com – Deep within a limestone passage beneath the boreal forest canopy near Fort Smith, researchers encountered an unsettling scene this past May. A motionless bat lay draped across a rocky ledge, its form encrusted with delicate white filaments. When headlamps illuminated the chamber, a second creature emerged—this one bearing the telltale fungal growth along its wing membranes. The startled animal emitted a sharp hiss before retreating into a narrow fissure in the rock face.

For Jesika Reimer, an ecologist dedicated to monitoring northern bat populations across Canada and Alaska, the sight confirmed long-held fears. White-nose syndrome, a devastating illness triggered by the fungus Pseudogymnoascus destructans, has been marching westward across the continent for two decades. This pathogen has claimed more than 6.7 million bat lives, attacking the facial regions, wings, and forelimbs of hibernating creatures. As infected bats periodically awaken to groom themselves, they rapidly deplete the fat reserves essential for winter survival, ultimately succumbing to dehydration or starvation. Smaller species with limited energy stores face the greatest danger.

A Critical Milestone in Disease Spread

Fort Smith sits approximately 450 miles south of the Arctic Circle, marking a significant geographic threshold for the disease. Joanna Wilson, a biologist with the Northwest Territories government, explained the significance of this moment. “For 20 years, we’ve been tracking the spread of white-nose syndrome across the continent,” she noted. “We always knew it would eventually get here.”

The timing proved particularly unfortunate for conservation efforts. Researchers had planned to establish baseline measurements of healthy, stable bat populations before the fungus arrived. In 2025, white-nose syndrome was first documented in a Fort McKay cave in Alberta, located nearly 200 miles to the south. “We thought we’d have a year or two,” Reimer recalled. Now the pathogen has reached the northernmost known hibernaculum—a shelter where bats spend the North American winter—prompting urgent questions about potential devastation to regional bat communities.

The Karst Landscape and Its Hidden Treasures

The caves surrounding Fort Smith were initially identified in 2010 by a wildlife technician conducting aerial surveys. From above, the technician observed distinctive karst topography—landscapes created when soluble bedrock such as limestone or dolomite dissolves over time, forming underground caverns and sinkholes. These geological formations provide ideal conditions for wintering bats, offering stable temperatures and humidity levels throughout the cold months.

The technician subsequently conducted a ground expedition to verify the discovery, confirming the presence of a hibernaculum. Two additional caves were soon located in the vicinity. Prior to these findings, scientists remained uncertain about where the Northwest Territories’ hibernating bat species spent their winters. While summer colonies had been identified, suggesting bats remained in the region during colder months, the exact locations and population numbers remained unknown.

The largest of these formations contains eleven chambers and houses an estimated 3,000 bats, making it western Canada’s most significant hibernaculum. This cave has proven invaluable for understanding northern bat behavior. During her postgraduate research in 2011, Reimer investigated how bats survived at such extreme northern latitudes, where summers feature cooler temperatures, shorter daylight periods, and nearly continuous sunlight. She discovered that northern populations developed unique survival strategies, including foraging at dusk rather than complete darkness to hunt mosquitoes and moths, and consuming greater quantities of orb-weaver spiders, which provide higher energy content to maintain fuel reserves.

Species at Risk and Adaptation Efforts

Despite remarkable adaptive capabilities, smaller bat species remain highly vulnerable to white-nose syndrome. Both little brown bats (Myotis lucifugus) and northern long-eared bats (Myotis septentrionalis) carry special concern status in the Northwest Territories. Since the fungus first appeared in New York state in 2007—believed to have arrived from Europe attached to a caver’s footwear—it has eliminated 90 percent of little brown bats and 99 percent of northern long-eared bats in affected caves.

Reimer highlighted that some little brown populations are gradually recovering through genetic adaptation. These bats are modifying their metabolic rates to conserve fat and resist infection more effectively. However, the outlook remains grim for northern long-eared myotis bats, which weigh merely 6 to 9 grams and lack sufficient energy reserves to endure white-nose syndrome through an entire winter season. “If it hits them as hard as it has elsewhere in their range, we can expect them to completely disappear from the ecosystem,” Reimer warned.

Researchers are now exploring probiotic treatments as potential interventions. By introducing beneficial bacteria to bat populations, scientists hope to create biological barriers against the fungal pathogen. This approach could prove crucial for preserving species that might otherwise face local extinction. The coming years will reveal whether these interventions can provide sufficient protection for northern bat communities as the disease continues its relentless advance through previously unaffected territories.