Every year, hundreds of bats cluster together in a dimly lit cave in Southeastern Idaho, hibernating for the winter near the border of Utah. Hidden in the nooks and crevices of the 3,000 foot long Minnetonka Cave, at least seven different species of bats call the place home. Rita Dixon, Idaho State Wildlife Action Plan Coordinator, and her team have spent four years climbing into the cave, which is closed to the public nine months out of the year, to vaccinate the hibernating bats one by one against a fungus that causes the lethal white nose syndrome. The bat team navigates up 888 cold, slippery stairs to find where the bats hang out. With only a couple of scientists, batches of federally-funded test swabs, and a short number of hours in a day, they race to try and get enough of the creatures vaccinated during the winter months to create herd immunity. 

Bats across North America are fighting white nose syndrome for their right for deep, uninterrupted rest that ensures their survival until spring and the feast of insects that await them when they wake from their slumber. The fungus only grows on bats when their body temperature drops during hibernation. Over several weeks or even months, infected bats grow visible white fungus on the skin around their muzzles, ears and wings. This causes the bats to warm up while fighting the infection which then leads them to wake up prematurely in winter. By waking up more often when they’re supposed to be hibernating, infected bats disturb their neighbors and burn through their fat storage faster, ultimately succumbing to starvation.

White nose syndrome is considered one of the worst wildlife diseases of modern times, according to a report by the Utah Division of Wildlife Resources. As of February, scientists in the eastern United States had seen up to 99% of bat populations wiped out in some of the nation’s largest colonies. Throughout the West, it isn’t known how many bats currently have white nose syndrome, due to the difficulty in locating and catching bats for testing. However, bats with white nose syndrome have now been confirmed in over 40 states and nine Canadian provinces, according to the U.S. Fish and Wildlife Service. In the American West, the fungus has been found in every state except Oregon and Nevada.

“We’re talking about an entire population being wiped out,” Julie Weckworth, a disease ecologist who studies bat species adapting to climate change and white nose syndrome, said. “I didn’t get that until I actually saw the count.” 

While looking at the data gathered by biologists in the East, Weckworth was stunned to see in 2006 there were 10,000 bats in some caves in the region, but in 2007 there were only 100 bats left. “It’s just crazy,” she said. 

Currently, 13 bat species, including two endangered species and one threatened species, have been confirmed with white nose syndrome in North America. Due to their small size, the endangered species of little brown bats are more vulnerable to succumbing to the disease and have died in droves across the East. 

The fungus was first found in upstate New York in 2006 and is widely thought to be transferred by people who had been in areas overseas, like Europe or Asia, where the fungus originated. While transmission of the fungus is mostly spread from physical contact between bats, people can also spread the fungus if they visit multiple caves or roosting spots where bats are infected. 

While not all bats who have the fungus get white nose syndrome, and not all bats who have white nose syndrome perish from the disease, the fungus is a silent killer. Due to the massive death rates of bats in the East over the past two decades, Western bat specialists are highly concerned about the appearance of the disease in western states. 

On top of the breathtaking loss of animal life this disease has taken, it’s estimated that in North America the decline of bats could lead to more than $3.7 billion per year in agricultural losses, according to Dixon. Except for a few species in the Southwest who are pollinators, almost all bats in the West are insectivores who feed on millions of pounds of insects that would otherwise eat crops intended for human and livestock consumption. 

“Our bats are essential to our environment. Whether you’re a rancher or a farmer, keeping the system intact benefits everyone,” Dixon said.

A report released in September 2024 alarmed the scientific community who were following the destructive path of white nose syndrome. According to the study, farmers in counties in Illinois where large numbers of bats were killed by white nose syndrome increased their insecticide use by over 30%. It was then documented that infant mortality rates due to internal causes of death increased by nearly 8% on average in those same white nose syndrome-affected counties.

A joint meeting between states, federal agencies, and tribes in February outlined national priorities for this year’s winter, spring, and summer white nose syndrome response that has already begun, Dixon said. “We’re going to be focused on early detection of the fungus where we have not detected it before and be on the leading edge of where it’s spreading.”

Daniel Neubaum, Species Conservation Program Manager for Colorado Parks and Wildlife and a member of the Western Bat Working Group, said, “things are definitely evolving because the disease is now in Colorado, and it’s spreading right now as we sit here.” In 2024, it “blew up” along the Front Range.

Besides the immediate impact on farmers and ranchers who may have to buy expensive pesticides for their crops to compensate for the lack of bats, a dramatic decrease of bats could reshape the ecological landscape of the West over time, Neubaum said. “All these things tend to have a trickle-down effect if you see really large declines in a species.”

Colorado is focusing on new efforts this year, including increasing sample collections at sites across the state. “Our interest there is to see if Western bats may actually fare a little better with this disease than where we’ve seen elsewhere like back East,” Neubaum said.

Kimberly Hersey, Mammal Conservation Coordinator for the Utah Division of Wildlife Resources, said for Western states like Utah, there isn’t a lot that can be done to stop the spread of white nose syndrome due to the difficulty in finding and reaching the spot where bats roost. In northern and eastern parts of the country, bats roost in large numbers in caves more easily identifiable by humans. In Western states, the varying cracks, crags, and holes in the expansive plains and mountain landscapes prove more difficult for locating bat colonies.

While bats across the nation may be facing the largest threat to their kind in decades, with help from humans and a little luck, scientists have hope that the plains, mountains, and prairies of the West will still be called home for millions of members of this critical species. 

All across the United States, scientists and researchers are finding new ways to help bats survive white nose syndrome. Millions of dollars have been provided for new research projects looking at how bats could evolve to fight the disease in the long term, while multiple teams of scientists currently try innovative ways of inoculating bats against the fungus.

To date, Dixon, the Idaho scientist, said vaccines for bats have been given via oral pipette, which is highly labor intensive. To combat any large spread of the fungus to bats, Dixon and her team plan to try vaccinating the bats this summer with a topical application that is sprayed on them while they are roosting large numbers. That way, the bats will inoculate themselves when they ingest the vaccine while grooming, which will hopefully reach a much larger number of bats at one time.

“Our bats are busy working the night shift while we’re asleep in our beds,” Dixon said. “They are out there working for us by eating all these damaging insects. And that protects us, it protects our water, and it protects our land.”