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Manitoba's Bats in Trouble

How White-nose syndrome is putting bats at risk

A relatively new disease is putting some of Manitoba’s bat species at risk, and could even drive some species to extinction. White-nose syndrome (WNS) was first detected in Manitoba in the winter of 2017/18, and now that it’s here Manitoba bats are at risk.

Above: hibernating bats (by Mary-Anne Collis)

“WNS is caused by a fungus called Pseudogymnoascus destructans,” says Quinn Fletcher, Research Associate in Dr. Craig Willis's lab at the University of Winnipeg. “The fungus grows on exposed tissues of bats, especially their wing and tail membranes, but also on their noses.”

White-nose syndrome can affect bats in different ways and to varying degrees. Not all species are affected by the fungus, and not all species are affected to the same extent. Some of Manitoba’s bat species, like the big brown bat (Eptesicus fuscus), are resistant to the fungus. But for some species, like the northern long-eared bat (Myotis septentrionalis), WNS could wipe them out completely.

“It is generally thought that this disease causes mortality because infected individuals arouse too frequently from hibernation, which exhausts their energy reserves before the end of hibernation,” says Fletcher.

The most common hibernating bat in Manitoba, the little brown bat (Myotis lucifugus), could be more vulnerable than other species. With population declines of the little brown bat in Ontario already exceeding 90%, it’s expected that Manitoba’s populations will be similarly devastated.

“The reduction in bat numbers may have an impact on the agricultural and forestry sectors,” says Fletcher. “Bats feed on important pest insect species for these sectors and there is a risk that pesticide use will need to increase due to the absence of bats.”

However, there is evidence that the little brown bat population may stabilize at low numbers, and some research suggests that there will be population increases in species which are resistant to the fungus, such as big brown bats. How this will affect the ecosystem and biodiversity as a whole is unknown.

The disease has been spreading each year since it was first found in North America in 2006, and according to, it continues to spread rapidly across the United States and Canada, mostly through bat-to-bat contact.

Because WNS is caused by a fungus, the disease will be difficult to manage, and nearly impossible to eradicate in Manitoba and elsewhere. “Even in the absence of bats, it seems like the fungus causing white-nose syndrome can persist within caves and mines,” says Fletcher.

According to Fletcher extensive research is under way to look for treatments for WNS. And although some preliminary lab and field trials have succeeded in increasing survival by between 30% and 40%, treatments might be difficult to administer. 

“In Manitoba, we only know where a small proportion of bat hibernacula are located,” says Fletcher. “As a result, even if a really good treatment was developed, we could only find and access a small proportion of the infected bats to help.”

If all areas containing the fungus could be found, Fletcher says cleaning up spores chemically from the environment could likely be done. But the decision to do this would be difficult since this could cause treatment-associated side-effects, such as negative effects on biodiversity and the potential to create a treatment-resistant strain of the fungus. 

Although white-nose syndrome is now in Manitoba and the outlook for managing the disease does not look promising, research on WNS in the Willis Lab will continue. In the meantime, Fletcher says we should focus our attention on protecting the bat habitats.

“A small proportion of bats with WNS survive the winter and may be able to pass on “survival traits” to their offspring if they can reproduce in spring,” he says. “To increase the chances that bats will be able to successfully reproduce, their habitat needs to be preserved.” (Donate directly to the Willis Lab crowdfunding page found here.)

And as individuals, Fletcher says we can also do our part to help slow the spread of the disease. “All people entering caves that are potentially infected with the fungus, and then planning to visit other caves must properly decontaminate their gear.” (Learn how to properly decontaminate your gear here.)

The Willis Lab also has a citizen science program called bat Watch that involves the general public in studying bats and WNS. The Willis Lab Bat Watch webiste provides extensive information about bats, and there citizen scientists can also upload the location and counts of summer colonies of bats. These data help bat researchers to increase their knowledge of bat natural history, which may serve useful for WNS-related management actions. The website also encourages the public to provide reports of any unusual bat behaviour in winter and early spring. If you observe bats flying outside of hibernation sites when there is still snow on the ground, or bats flying or roosting outside anytime during winter (i.e., November to May) please contact the Canadian Wildlife Health Cooperative (CWHC) at 1-800-667-1940 or email the Willis Bat Lab citizen science program

Learn more about the Willis Lab here.  
View a map of the where WNS has been found here.