A deadly fungus is driving these bats toward extinction, the government says

It thrives in the cold and dark, infesting the muzzles of sleeping bats. The deadly fungus hops from bat to bat, stirring the winged mammals from their winter slumber while they cluster in caves. It can drive bats to dehydration and starvation, leaving cave floors littered with carcasses.

The US Fish and Wildlife Service on Tuesday announced it would propose adding the tricolored bat, one of several species affected by the deadly fungus, to its list of endangered species. The bat’s population has declined so dramatically over the past decade that it may now vanish from the wild.

The decision by federal wildlife managers underscores the threat of extinction facing hundreds of thousands of species worldwide. The decline of bats in particular — due in part to deadly diseases, as well as other harms — threatens to upend ecosystems and hurt farms that rely on the voracious insect-eaters as pest control.

The culprit harming these bats is known as white-nose syndrome, a nonnative fungus first discovered about 15 years ago in an Upstate New York cave that has since spread across more than half the bat’s range. Sick bats — with fuzzy growths on their noses — have been found from the Atlantic coast to the foothills of the Rockies, with impacted colonies seeing declines of more than 90 percent.

“It’s pretty heartbreaking to go in and see what were once huge colonies of bats that are now struggling,” said Jonathan Reichard, the national white-nose syndrome assistant coordinator at the Fish and Wildlife Service, describing caves where he would see “dying bats crawling around in the snow.”

The tricolored bat in particular “has been in trouble for a long time,” said Beth Buckles, an associate clinical professor of wildlife pathology at Cornell who co-wrote a major paper describing the disease. She thinks the decision is long overdue.

“It takes a while to get things listed, I understand that,” she said. “But bats are in a really bad way.”

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No one is quite sure when or how white-nose syndrome arrived.

“We’ve always assumed that it was what we call human-mediated transportation,” said Jeremy Coleman, national white-nose syndrome coordinator for the US Fish and Wildlife Service. Experts suggest it could have arrived, for example, on the boot of a spelunker who trekked it in from Europe or Asia.

But scientists are sure the fungus — dubbed Pseudogymnoascus destructans for its destructive nature — is not from around here. “We are very confident that it is not a native fungus to North America,” Coleman added.

With powerful immune systems, bats can harbor many pathogens without getting sick — including, potentially, the coronavirus behind the pandemic among humans.

But the cold-loving fungus has evolved to attack bats at their most vulnerable, during hibernation when they huddle together. Like a vampire, the fungus works best in the dark. Despite its name, the disease can also creep along bats’ wings, leaving lesions and making it harder for the mammal to retain water.

“We call it white-nose syndrome,” Buckles said, “but the fungus is all over their wings.”

The tricolored bat gets its name from the alternating dark and light patches on its fur. In warmer months, the tiny mammal feasts at night on beetles, moths and other insects along river banks and at forest edges. They find food in the cover of darkness by screeching an ultrasonic pitch and listening for it to bounce back.

The tiny species, which can weigh less than a quarter, faces threats beyond this disease. Shifts in temperature and precipitation due to climate change can disturb roosting and foraging. And the blades of wind turbines can strike and kill the animals.

But white-nose syndrome remains by far the biggest menace.

A dozen different bat species are affected by white-nose syndrome. Federal officials proposed earlier this year to list the northern long-eared bat as endangered. The agency is considering granting a third species, the little brown bat, federal protections as well.

And the endangered Indiana bat was on a path to recovery before the arrival of white-nose syndrome, said Winifred F. Frick, chief scientist at the nonprofit Bat Conservation International.

“As we all experienced during covid, responding in real time to disease is really challenging,” she said. “And it’s even more challenging when you’re talking about wildlife.”

Passed nearly a half-century ago, the Endangered Species Act makes it a crime for people to harass animals threatened with extinction. The law has been critical for reviving the numbers of gray wolves and other iconic North American creatures from poaching and habitat destruction.

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But the agency acknowledges that imported diseases pose a different kind of threat. Researchers are now exploring a plethora of novel treatments — including antifungals, probiotics, ultraviolet lights, vaccines and even genetic engineering — to fight the fungus without harming other species. The Fish and Wildlife Service will take public comment for 60 days before making a final decision on the tricolored bat.

“We didn’t even know the disease existed until 12 years ago or so,” Coleman said. “Coming up with these strategies to treat wildlife disease is somewhat unprecedented.”

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