THEBACHA/FORT SMITH - It seems some bats have a favourite winter destination – the karst caves around Fort Smith and in the northern section of Wood Buffalo National Park.

Dr. Cori Lausen holds a bat in her hand while doing research in Wood Buffalo National Park. - photo courtesy of Parks Canada

In September, the bats were the subject of a study, the first since the 1970s.

"It's certainly a very important area for bats overwintering," said Dr. Cori Lausen, a researcher from British Columbia.

Her hypothesis is bats fly in from elsewhere in the NWT, northern Saskatchewan, and possibly northern Alberta.

"We don't know at this point how large an area," she said.

She believes the bats could be coming from as far north as Yellowknife.

Lausen spent five nights in the Alberta section of the park beginning on Sept. 10, followed by five days in the Fort Smith area of the NWT.

"The idea was really to look for bats in the area to potentially find out if they were hibernating there and, if so, what species would be overwintering," she said.

The research concentrated on karst caves and sinkholes that create chambers in the ground. Each could become a hibernaculum – a place where bats go dormant for the winter.

Overwintering means travelling – sometimes hundreds of kilometres – to an area to hibernate in caves.

"But we don't call that migration," Lausen said, explaining migrating bats travel into the U.S. to feed on insects during the winter.

The researchers in the 1970s determined there were three bat species in the area – little brown, big brown and northern myotis.

"Nobody has gone back in and determined if the bats were still there, if we still had those species and how many bats," Lausen said, adding the earlier researchers counted about 150 bats.

She found the three species are still in the area, but she has a much higher estimate of their numbers.

"It is so hard to say," she said of a population figure. "I will tell you that the magnitude is definitely thousands, but where that ends I have no idea. I mean it's such a large area we're dealing with and a number we probably won't ever be able to count."

During her study, she either captured bats in mist nets or recorded their sounds with acoustic instruments.

Lausen said it is becoming increasingly important to find out where bats hibernate, because of white nose syndrome which is rapidly spreading from east to west in North America.

"It's a fungus that's basically wiping out bats while they hibernate," she said, noting the fatality rate in some hibernacula is about 90 per cent.

White nose syndrome – which originated in Europe – showed up in 2006 in a single recreational cave in Albany, New York. It is suspected a caver brought the fungus from Europe in spores in the mud of his boots.

Lausen said white nose – a unique fungus that only grows on mammals with a body temperature below 12 degrees Celsius – has moved west at about 800 km a year.

Technically, the fungus itself doesn't kill bats.

As Lausen explained, bats might come out of hibernation during the winter and notice the fungus. They will then start grooming to get rid of the fungus and their immune system will also reactivate.

Once the bats go back into hibernation and become colder, the fungus starts to grow once more, so the bats have to keep their bodies warm, she said. "They burn through all their fat and die before the end of winter. So it's starvation that kills them."

Lausen said there are many variables which will determine when and even if white nose syndrome will make it to the Fort Smith area, such as climate and whether eastern and western bats mix.

"We don't know how much time we have," she said.

With knowledge of hibernacula locations, strategies to combat the fungus may be possible.

For instance, Lausen said certain bacteria keep the fungus from growing on some bats.

"If we know where our bats hibernate, in theory we could do something like go in and mist the whole hibernaculum down with this bacteria," she said.

European bats do not die from white nose. It appears the fungus may have killed most European bats thousands of years ago, and the 10 per cent that survived resulted in resistant species.

Lausen said bat populations would take a very long time to recover with only a 10 per cent survival rate in North America. "Once we see our bats die off, we will not see them recover in our lifetimes, if ever."

She said some bats live about 45 years, but only one young per year is born to a female bat.

Lausen undertook her research in conjunction with Wood Buffalo National Park and the GNWT.

Allicia Kelly, a regional biologist with the Department of Environment and Natural Resources, said it was the first time bats have been surveyed in the Fort Smith area of the NWT.

"So it's part of an initiative to learn more about what is in the NWT," Kelly said. "Knowing what lives here is an important part of understanding the environment, understanding our biodiversity and also being able to monitor for change."

She said while the research confirmed three bat species overwinter in the area, it is still unknown what bats are there in summer.

Aside from species and numbers, Lausen found some other interesting facts about the bats.

Big brown bats are "absolutely massive" compared to the same kind in other parts of Alberta, she said.

Bats also fly at really cold temperatures in the area, apparently because insects also fly in the same colder temperatures.

"Bats eat a lot of insects," Lausen noted. "So they're a pretty valuable part of our system here."

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