White-nose syndrome found in Manitoba's Riding Mountain as deadly bat disease pushes farther west
Rapid spread of fatal fungal infection across Manitoba is cause for concern, says bat researcher
The fatal bat disease known as white-nose syndrome has been found in Manitoba's Riding Mountain National Park, the westernmost location where the infection has been found in Canada.
Six bats were found dead or dying from white-nose syndrome this spring and summer in Riding Mountain, located about 250 kilometres northwest of Winnipeg, Parks Canada disclosed on its website in July.
The infected bats were found near the park's east gate as well as in Wasagaming, the townsite in the centre of the park.
White-nose syndrome was first detected in Manitoba in the Interlake region in 2018. The Interlake is home to several large bat hibernacula — the underground caves or abandoned mines where the small mammals overwinter.
University of Winnipeg biologist Craig Willis said while it's no surprise to see the disease continue to march west, he remains concerned about the distance covered in only one year.
"It's spread really quite quickly to make it all the way across Riding Mountain so fast," said Willis, who studies bats and is trying to find ways to help them recover from white-nose syndrome.
"In this case, we actually didn't find the hibernacula and no one knows where these particular bats hibernate," he said. "So we're actually not sure where they came from, where they got the disease and where they spent the winter."
White-nose syndrome is caused by a fungus that attacks exposed skin on a bat's ears, wings or nose while the mammal hibernates. The fungus, an invasive species from Europe, thrives in cool, humid environments.
The infection causes bats to wake up too early during hibernation, leading them to burn up valuable calories and eventually starve to death — or freeze to death in search of insects to eat at a time of year when there are no insects flying around.
"They really struggle when they come out of hibernation and try and recover from this disease, and that's what we think happened to these guys," said Willis, referring to the bats found at Riding Mountain.
"They were totally emaciated. Several of them were dead when they were found."
Willis said it isn't clear whether the bats were infected in the Interlake and flew to Riding Mountain, or were infected in hibernacula closer to the park.
White-nose syndrome was first discovered in Manitoba at a cave near Lake St. George, in the northern Interlake. The province has since taken measures to prevent people from entering bat caves in an effort to prevent the movement of fungus.
"That can't prevent the spread. It can only slow the spread. Bats move freely from hibernaculum to hibernaculum," said Bill Watkins, a provincial zoologist in charge of biodiversity conservation.
Watkins said the province is expecting mortality rates of 80 to 90 per cent in caves infected with the fungus.
The bats in Interlake caves where the infection has been confirmed are not doing well, Willis said, adding one particular site in the Interlake has been devastated.
"As of last winter, we'd gone from about 400 bats per winter down to when we counted this this winter, only three pretty crusty-looking, emaciated bats that probably wouldn't have survived, unfortunately," he said.
Biologists will get a better idea of the impact of white-nose syndrome this winter, Willis said, when they intend to visit six or seven hibernacula.
Little brown bat 'absolutely crushed'
There are a total of six species of bats in Manitoba. Three spend the winters hibernating in the province, and three migrate south for the winter. All three overwintering species are at risk from white-nose syndrome and are considered endangered as a result, Willis said.
The little brown bat, the most common bat species in Manitoba, is getting "absolutely crushed" by the disease, he said.
"They're super-common bats in this sort of agricultural, rural matrix where we probably depend on bats, to some extent, for pest control above crops. So that's a particular worry."
The less common northern myotis, also known as the northern long-eared bat, is at risk of extinction, while the big brown bat appears to be more resilient, he said.
"It's much more flexible in where it can hibernate and it does a whole lot better hibernating in buildings and other kinds of structures, where it can deal with drier conditions that are probably not as good for the fungus. And so we don't see them suffering as big impacts," Willis said of the big brown bat.
"There's some evidence from the lab, as well, that they're resistant — that the fungus doesn't grow as well on or into their skin as the more affected species. And so they're doing much better, even though we know they can get sick."
Willis said Manitobans concerned about the loss of bats can help by preserving bat habitat — often, wetlands located next to old forests — and building or installing bat boxes.
He urged anyone who stumbles across a bat colony or notices a bat flying around in the winter, when it ought to be hibernating, to report their findings to biologists by visiting batwatch.ca.
The only Canadian provinces free of white-nose syndrome so far are Saskatchewan, Alberta and British Columbia.
The disease is closing in on Saskatchewan, as it's now been found in both Manitoba and North Dakota. It's also near B.C., having been found in the Seattle area of Washington.