Bat populations have 'crashed' across Manitoba since arrival of deadly white-nose syndrome: biologist

A Manitoba biologist says he's hopeful the province's bat population will gradually start to recover, after the arrival here of a deadly bat disease that has killed thousands of the flying animals across the province.

White-nose syndrome — a fatal infection caused by a fungus — was first found in Manitoba in the Interlake region in 2018. 

It has killed millions of bats since it was first seen in North America in upstate New York in 2006. Since then, it has spread westward across Canada.

"It's basically everywhere we've looked for it across the province," said University of Winnipeg biologist and bat researcher Craig Willis, whose U of W lab hosted a conference for researchers from across North America this week.

"Our populations across the province have crashed."

White-nose syndrome is caused by an invasive fungus species that attacks exposed skin on a bat's ears, wings or nose while it hibernates in the winter. The fungus, which thrives in cool environments, causes bats to warm up too much, Willis said.

That makes them burn through their fat reserves too quickly and eventually starve to death.

"We know there [were] thousands if not hundreds of thousands [of bats] … before the disease, and we don't know where they are," he said.

"Some of our hibernation sites are now completely empty — there are no bats left at all," he said, adding that the site in the Lake St. George ecological reserve west of Lake Winnipeg, where the disease was first detected in Manitoba, has seen its bat population drop to about 20 per cent of the bats that once hibernated there.

"When you care about these animals and you're seeing them suffering and dying from a terrible disease that people probably accidentally introduced to North America in the first place, that's frustrating and sad and a bit hard to take," said Willis.

Some bats recovering

Though the disease has been devastating, Willis said he's hopeful populations will level off. That's something he's already seeing at the Lake St. George site, where the population has stabilized at about 2,500 bats, he said.

"Hopefully we're kind of through the woods of the population collapse, and slowly our populations might start to recover if we do the right things," said Willis. 

In eastern North America, where the disease first began spreading years ago, populations of the little brown bat — a species that was the most common in Manitoba before the disease put it on the endangered list — are slowly recovering.

That species is one of three hibernating bat species in the province. Another three in Manitoba migrate south for the winter.

To learn more about how bats can recover from the disease, Willis has also been experimenting with heated artificial roosts, or bat boxes. By heating the habitats where bats raise their pups to a comfortable air temperature, he's hoping to see whether populations bounce back faster.

The results so far seem to be promising, he said.

Bat conference

The impact of white-nose syndrome is also being studied worldwide. The University of Winnipeg's Bat Lab, led by Willis, hosted the 51st annual meeting of the North American Society for Bat Research in Winnipeg this week.

The conference, which began Wednesday and wraps up Sunday, drew more than 330 bat scientists from around the world, including Rodrigo Medellin, a bat researcher from Mexico.

He said white-nose syndrome is one of the main threats the mammals face, along with the destruction of their habitats — wetlands and old forests.

The fungus hasn't yet been detected in Mexico, Medellin said at the conference on Thursday.

"The fungus is a cold-loving fungus, and we don't have these very long, very cold winters that [Manitoba has]," he said.

"When finally the fungus makes it into Mexico, I don't think — knock on wood — that we're going to have the high levels of mortality that it has affected here."

The U of W's Willis said protecting bats in Manitoba comes down to preserving their habitats.

People who see bat colonies can report them to batwatch.ca, which can help biologists learn where to set up bat boxes, Willis said.

The conference will end Sunday afternoon with a public workshop at FortWhyte Alive, where visitors can learn about bats and take a virtual reality tour of the Bracken Cave Preserve in Texas — the world's largest bat colony.