Millions of bats have died from contagious illness. First signs were just found in Idaho

A fungus that causes a fatal illness in bats has been detected in Idaho for the first time, federal and state officials confirmed.

Traces of the Pseudogymnoascus destructans fungus, commonly known as Pd, were detected on six bats in Minnetonka Cave, which is located on the Caribou-Targhee National Forest near the Utah-Idaho state line. The Idaho Department of Fish and Game said despite the presence of the fungus, no bats in the cave appear to be exhibiting symptoms of white-nose syndrome, the fatal disease caused by the fungus.

Rita Dixon, state wildlife action plan coordinator for Fish and Game, told the Idaho Statesman in a phone interview that the agency has been bracing for the fungus to arrive for years. Dixon said the fungus is believed to have originated in Eurasia. National Geographic reported that it has killed more than 6 million bats since it was first documented in North America in 2006.

Dixon said protecting bats is important for many reasons. All of Idaho’s bat species are insectivores, and they feed on bugs that can destroy crops and carry diseases to humans.

“We need our bats,” Dixon told the Statesman. “They’re not only worth a lot just intrinsically, but they’re important to Idaho’s economy, they’re important to ecological systems.”

Fish and Game has been monitoring for the fungus for a decade, and protocols have been in place at Minnetonka Cave – which sees thousands of visitors every year – for several years to try to prevent fungal spores from being introduced.

Dixon said the fungus is primarily spread from bat to bat but could also be transmitted through people’s clothing, gear or equipment.

“The problem is our bats in North America did not evolve with this fungal pathogen, so they didn’t have the immune system to fight it,” Dixon told the Statesman.

While Fish and Game and Caribou-Targhee National Forest officials learned of the discovery in recent days, Dixon said the fungus was detected in samples collected in October. Since then, she said, biologists have visited Minnetonka Cave twice and found no visible indications of the fungus or any sign of sick or dead bats.

What is white-nose syndrome?

White-nose syndrome is the illness caused by Pd fungus. Though Pd was found in three species in Minnetonka Cave (little brown myotis, long-legged myotis and yuma myotis), none of the bats had white-nose syndrome.

The disease gets its name from the white fungus that can be seen on the faces and bodies of some bats. But Dixon said the fungus does damage on a cellular level.

“One of the distinguishing things about this fungus is it actually invades the fur-less membranes” like ears and wings, Dixon said. It’s not entirely clear how the fungus wreaks havoc, but Dixon said scientists believe it can cause water imbalances in the cells and cause hibernating bats to dehydrate. It can also rouse the hibernating bats, causing them to burn through precious calories in the winter.

“For bats, getting through months of hibernating requires they have the energy stores they need to survive the winter,” Dixon said. “If they’re repeatedly having to wake up, that uses energy.”

Finally, the fungus can cause membranes to become necrotic, dying off and creating holes in bats’ wings. Bats with damaged wings are unable to fly and will eventually starve to death, Dixon said.

White-nose syndrome hits hibernating bat species especially hard and can affect entire colonies when hundreds or even thousands of bats share a roost for the winter.

Are Idaho bats at risk?

Idaho is home to 14 bat species, and several of them are potentially at risk if white-nose syndrome takes hold in their populations. Dixon said a genus of bats, known as myotis – or mouse-eared – bats, is particularly at risk. Six of Idaho’s bat species are part of the myotis genus.

Dixon said the Western small-footed myotis is of particular concern. Pd has been observed on the species before, but white-nose syndrome has not been observed in Western small-footed myotis.

“The reason that is one of our highest concerns is because that particular myotis species aggregates during the winter in some roosts in Idaho up to 400 bats,” Dixon said. “If white-nose syndrome got into that colony, we don’t know what would happen.”

Some of Idaho’s other species, including the silver-haired bat and Townsend’s big-eared bat, appear to be at low risk for the disease.

Dixon said there is “some evidence of some bats that have been exposed and have gotten through it and survived,” but the main goal now is to prevent Pd from spreading to other Idaho caves.

Fish and Game will work with partners including the Forest Service and U.S. Geological Survey to implement more preventative strategies at Minnetonka Cave and build a plan from there.

Fish and Game urged the public to help survey for white-nose syndrome by reporting any instances of several sick or dead bats in the same location within a short period of time. People can also watch for physical signs of white or grayish fungal spores on bats, which typically can be observed between November and May.

Anyone who suspects the presence of white-nose syndrome should report their information to Fish and Game’s wildlife health reporting webpage.