White-nose syndrome, a lethal fungal disease that has killed more than 6.7 million bats across North America over two decades, has reached the northernmost-known hibernaculum near Fort Smith in Canada’s Northwest Territories. According to bat ecologist Jesika Reimer and government biologist Joanna Wilson, biologists discovered infected bats covered in the spindly white fungus Pseudogymnoascus destructans (Pd) inside a limestone cave system roughly 450 miles south of the Arctic Circle.
How White-nose Syndrome Kills Hibernating Bats
The fungus attacks the face, wings, and arms of bats while they hibernate. When the infection irritates the animals, they stir from rest and groom themselves, burning through the critical fat and energy reserves needed to survive the winter. Smaller species, particularly little brown bats and northern long-eared myotis bats, are especially vulnerable to dying from starvation or dehydration.
In the caves where the fungus has spread, it has wiped out 90% of little brown bats and 99% of northern long-eared myotis bats since first appearing in New York state in 2007. While some little brown populations are slowly rebounding, the prognosis for the northern long-eared myotis remains grim. Weighing just 6-9g, the species lacks the fat reserves to outlast white-nose syndrome through the winter. According to Reimer, if the fungus hits them as hard as it has elsewhere in their range, researchers can expect them to completely disappear from the ecosystem.
Discovery at the Northernmost Hibernaculum
The infected bats were found in May inside an 11-chambered cave that shelters an estimated 3,000 bats, making it the largest hibernaculum in western Canada. Wildlife technicians first located the caves in 2010 after spotting a distinctive karst feature below from the air. In subsequent years, researchers like Reimer studied how bats adapted to survive extreme northern latitudes by foraging at dusk and consuming high-energy orb-weaver spiders.
When researchers returned in May to capture bats with lightweight mist nets, they documented clear signs of necrosis on wing membranes, where living tissue dies. According to Wilson, field teams also observed sick bats flying outside in daylight and discovered an infected bat, badly dehydrated, at a nearby lake with wings as brittle as tissue paper.
Did you know? Karst landscapes form when soluble bedrock like limestone dissolves, creating underground caves and sinkholes that provide wintering bats with an ideal habitat.
Potential Factors Offering Cautious Hope
Even though laboratory tests confirmed white-nose syndrome had arrived, scientists did not witness the catastrophic die-offs previously recorded in southern cavern systems, such as recent observations in the Rocky Mountains of Alberta. Wilson noted that this difference could mean the fungus has not yet become established, or it could be related to the cave’s sub-arctic latitude giving bats an adaptive edge. While the fungus thrives at 10C (50F), northern cave chambers are much cooler, with some dropping below freezing throughout the winter, which may slow fungal growth.
In addition, researchers are applying an experimental probiotic cocktail. Developed at McMaster University from samples taken from the microbiomes on bats’ wings, the beneficial microbes possess anti-fungal properties and are applied to the surface of summer roosts to spread from bat to bat. Early field trials in British Columbia and Washington are yielding promising results, showing that among Pd-infected bats, those with the highest amount of probiotic microbes had the least Pd.
The Compounding Threat of Wildfires
Wildfires complicate the advance of white-nose syndrome for northern bat populations. According to Reimer, large fires in 2023 torched the trees surrounding the Fort Smith caves, leaving not a single piece of foliage to be found. This loss of habitat forces bats to travel longer distances to locate food, summer roosts in old decayed trees, and mates during the autumn breeding season.
Scientists are currently examining whether fire activity might have accelerated fungal transmission by driving bats out of the Northwest Territories southward, where they interacted with Pd-positive colonies before returning the disease to northern roosts. With interventions under consideration to give vulnerable species like the northern long-eared myotis a fighting chance, scientists must wait until next spring to determine the full impact.
Pro Tip for Wildlife Observers
Frequently Asked Questions
What causes white-nose syndrome in bats?
The lethal disease is caused by Pseudogymnoascus destructans (Pd), a spindly white fungus that attacks the face, wings, and arms of bats during hibernation.
Why are northern bats at risk?
While northern caves feature cooler temperatures that may slow fungal growth, smaller species like the northern long-eared myotis lack the fat and energy reserves to outlast white-nose syndrome through the winter.
Are there any treatments for white-nose syndrome?
Scientists are conducting field trials with an experimental probiotic cocktail derived from natural wing microbes, which aims to improve bats’ resilience to Pd infection by slowing its growth.
What are your thoughts on conservation efforts for northern bat populations? Leave a comment below or share this article to raise awareness about white-nose syndrome.
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