Bat researcher says finding healthy females with pups 'encouraging'

A summer survey of New Brunswick's bat population showed at least one encouraging sign for a species that has been devastated by a killer fungus — healthy moms with healthy babies.

Karen Vanderwolf started looking for maternity colonies this spring as part of her study of white nose syndrome, a fungus that has nearly wiped out bat populations.

"Back in 2011, when we first saw white nose syndrome come into the province, we were counting about 6,000 bats over the winter," said the New Brunswick Museum research associate.

But that number plummeted in the caves they surveyed. By 2015, the hibernating bats had all but disappeared.

"If I recall correctly, we counted about six individuals — that might have been seven individuals — so you can see a huge loss there," Vanderwolf said.

That's a 99.9 per cent mortality rate.

The fungus attacks when the bats are hibernating. 

During hibernation, bats lower their body temperatures to ambient temperature to save their fat reserves," said Vanderwolf.

"This is a problem because the fungus only grows at these cold temperatures that the bats hibernate."

The fungus will grow on any exposed skin surface of a bat, she said. 

"White nose fungus actually grows into the skin and replaces muscle fibres and blood vessels and causes a lot of tissue and water and electrolyte loss, which ends up killing the bats."

This past spring, researchers asked for the public's help finding summer breeding colonies to try to get a picture of how bats are doing outside their hibernation season.

"We got a huge response," Vanderwolf said.

"We got to learn about multiple maternity colonies of bats that we were unaware of, some of which I visited this past June."

Bats hibernate in cold caves but seek out hot places in spring and summer to have babies. Usually that means large hollow trees, barn lofts, attics and purpose-built bat boxes. 

Vanderwolf set up nets near those colonies to catch females. She said what she found was encouraging.

• Researchers want to find New Brunswick's surviving bats, and they need your help   

"All the colonies that I found, the bats looked really healthy," she said. "I was able to handle several pups, even."

When the babies are young, mother bats fly and hunt with their pups clinging to their bodies.

"It was really great to see these healthy pups and the bats are reproducing."

Vanderwolf hopes females that survived exposure to the white nose syndrome fungus will produce babies that are resistant.

"That is the hope, yes, that it has a genetic component," she said.

"The bats in Europe and Asia do occasionally develop the disease, but they generally don't die from it." she said. "We don't know why."

But even if researchers are seeing encouraging signs, it's a long road back.

Vanderwolf said species affected by white nose syndrome only have one pup a year. Even if the bats can adapt to fight off the fungus, she said, it could take hundreds of years to get back to 2009 numbers.

In the meantime, New Brunswickers can help by providing places for females to reproduce by placing one or more bat boxes on their property.

You can find more information about how to do that here on the Canadian Wildlife Federation's website.