“If bats were absent, the largest effect would be on insect populations—Montana’s species feed on agricultural pests like moths, cucumber beetles, corn earworms, and grasshoppers, as well as insects that feed on humans and cause disease, such as mosquitos,” said Hilty. “Estimates vary, but a single Little Brown [Bat] can eat 600–1,200 mosquitos in an hour. Multiply that up to the population level, and I think you can start to think about the impact bats have on insect populations and what the implications would be if bats were removed from a system, [for example] a rise in crop failure and human illness.” 

Why are bats important in Montana’s ecosystems? 

Bats save the U.S. agricultural industry billions of dollars annually, and Montana’s farmers, ranchers, and consumers benefit from the free assistance. According to Montana Fish, Wildlife and Parks (FWP), the agricultural pest control provided by bats in Montana is valued at 680 million dollars yearly. 

Bats are also important pollinators and seed dispersers worldwide. Some plants have even evolved to be pollinated by bats. “[Like] agave—if you like tequila, thank bats,” Hilty said. “On this front, the absence of bats would be felt globally, as entire plant communities could die or shift.”  

According to the senior zoologist for the Montana Natural Heritage Program, Dan Bachen, bats are also essential to our ecosystem in other ways besides eating things and being eaten by things. He confirmed that bats influence the biodiversity of not only the food web they’re part of, but also the landscapes they live in. “Within cave ecosystems, bats that are relatively well established have significant impacts, as they bring in nutrients from above ground and deposit them in caves,” Bachen said. “The guano they leave can provide a substantial food resource for cave species.”  

What threats do bats face? 

Unfortunately, despite being such an essential part of our ecosystem and pretty cool creatures besides, bats in our state currently face various threats. 11 of Montana’s 15 species are currently on the state’s list for species of concern, and one is a potential species of concern. 

“There’s wind turbine development, which disproportionately impacts some of our larger migratory tree-roosting bats,” said disease ecologist for Montana Fish, Wildlife, and Parks (FWP) Emily Almberg. They, unfortunately, collide with the blades, and so that’s one source of mortality. There’s thought that some of the human impacts on forest structure, even changes to human structures, can influence local bat populations.” 

However, one looming threat is much more alarming: a deadly fungal infection called white-nose syndrome (WNS). WNS first appeared in New York in 2006 and has since killed millions of bats across North America. As of the February 2024 report from the WNS Response Team, WNS has been found in 40 states and nine Canadian provinces. In some areas of the country, 90–100% of bat populations have already been destroyed by the disease.   

Hilty explained that wildlife experts first detected the fungus that causes WNS in Montana in 2020 in the eastern part of the state, followed by the disease. Now, she confirms that the fungus has been detected in four species across 16 counties within Montana. 

Almberg said that wildlife experts are already seeing impacts from the spread. She explained that the fungus thrives in cool, damp places like caves, where bats often go to hibernate. “Our hibernating species go into these environments that are infected, [and] they pick up the infection, which then can develop on their skin tissues and cause them to repeatedly rouse during the winter,” Almberg said. “It causes tissue damage, and if those animals repeatedly rouse, they burn through their fat stores.” 

According to the National Park Service, hibernation is one way bats survive prolonged periods of cold weather that drive away their food supply. During hibernation, a bat’s bodily functions slow down to reduce caloric energy costs by about 98%. In this state, bats can survive long winters without food. However, WNS causes bats to wake up during hibernation, causing them to burn through their winter fat stores. “In some cases, it’s starvation that causes the ultimate cause of death. In other cases, the tissue damage and the immune response can be quite severe, and they can die as a result of that,” Almberg said. 

“Azure Cave, which was our largest-known hibernacula in the state in the eastern half of Montana—that population was at about 2,000 before [WNS] hit, and it dropped to 30 animals. So, a massive decline, and that population has stayed depressed since the initial outbreak,” Almberg said. The FWP has since detected the fungus in other key cave systems where other bat colonies live, “so we’re expecting similar declines in those cave systems, unfortunately.” 

How are bats being protected? 

Hilty explained that there are still numerous knowledge gaps, making it difficult for wildlife professionals to manage populations. Almberg also addressed some of the challenges associated with studying bats. “They’re so tiny. It’s really difficult to use a lot of the tracking tools that we use for large mammals. They do make transmitter tags for bats, but many of them don’t stay on for more than about a month. And then if they crawl into a rockface, they disappear,” Almberg said. 

She said it’s too soon to tell what the ripple effects from these population losses will be, though U.S. Geological Survey and FWP acoustic monitoring is presently showing declines in bat activity in the state. “Right now, we don’t actively monitor insect populations, but it’ll be interesting to see if we do see some of these cascading impacts that have been hypothesized based on their role in the food web,” she said.  

Almberg stated that wildlife experts in the state have several protections in place to help protect bats. Specifically in the interest of preventing the human spread of WNS, she said FWP and its partners have all done significant outreach to the caving community and the public on the importance of decontaminating any gear that goes into caves. Additionally, she said that some agencies like the Bureau of Land Management and the Forest Service have either gated caves where bats hibernate or requested seasonal closures to minimize the disturbance of hibernating bats during the critical window of hibernation. 

“The reality is that there are very few regulatory measures that protect bats—outside of the Endangered Species Act—in Montana,” Hilty explained. “However, I think education and partnerships have been successful measures for protecting bats.” FWP is encouraging wind energy companies to take action to reduce bat fatalities at turbines, collaborating with homeowners, businesses, and wildlife control operators to help sustain healthy bat colonies, and working with the Forest Service to make sure bats are considered in forest planning. “FWP also works with other states and Canada to address conservation issues and work towards solutions—bats are volant after all, and they don’t see borders,” she said.  

Hilty explained that bats have a variety of habitat needs that vary by gender and reproductive status. These can include nurseries for mother bats to raise their young in, forests for roosting, and hibernacula for hibernating individuals. “Bats also need safe traveling corridors to get between roosts, drinking sites, foraging sites, and swarming sites—where bats congregate in large numbers and mate before hibernation,” she said.  

So, it seems there’s still a lot of work to be done and a lot of information that wildlife experts still don’t know about bats. Hilty explained that FWP has been working hard with its partners to find out more. “We have a pretty good idea of the geographic distribution for most of our bat species from acoustic and mist surveys across the state,” she said. “I think generally, bat numbers are higher in areas that have access to high-quality roosts and foraging and drinking areas.” 

Why do bats deserve our protection? 

Almberg said that bats, like many animals labelled “vermin,” are very much misunderstood. “The vast majority are not vectors of infectious disease for humans, for example,” she said. “I think if people had the opportunity to see one of them in hand and see them echolocate, their tiny ears moving as they pick up signals—they’re just really neat little creatures.” 

“Our natural ecosystems are analogous to an engine,” Bachen said. “We wouldn’t start pulling out various parts without understanding what they do within that engine. It’s incumbent upon us to understand them. Everything in an ecosystem has some role to play and is worthy of consideration.” 

So, the next time you see a bat flitting around the night sky in your neighborhood, remember that though they may be small, they are essential to the world as we know it.