Death in the Dark: The PNW's Race to Stop the Bat Plague

In the middle of a winter night, a bat flies overhead, disoriented, in search of mosquitoes to eat. He should be hibernating with the rest of his colony, but a white powder in his nose and on his wings is making him itchy, restless, and hungry. Tonight will be his last flight before he dies of hunger.

By the next morning, researchers will find his tiny body — yet another victim of the deadly white-nose syndrome (WNS).

Fourteen different species of bats live in the Pacific Northwest. Each species has its own behaviors, but they all share the same risk of being plagued by WNS, a white fungus that appears on the bats' muzzles, ears, and wings. WNS is caused by Pseudogymnoascus destructans, a fungus that thrives in moist, cool environments, precisely like the caves where the bats, sometimes thousands at a time, hibernate during winter. It was first seen 20 years ago in Albany, New York, and has since spread to more than 40 states, including Washington.

"It is a real irritant, and it can cause lesions on their wings. When infected, it feels as if you have some sort of psoriasis or a skin lesion; it gets stiff and brittle. Instead of being flexible, it cracks and bleeds, and a bat that can't fly won't survive," explains Ed Dominguez, a naturalist and one of the founders of Bat Activity Trends (BAT), a program now in its fourth year running at the Seward Park Audubon Center.

In addition to preventing bats from flying, WNS keeps them awake during hibernation, arousing them to go out and find food when, naturally, they should be resting. Since it's wintertime, their source of food is scarce, and with their wings stiffened by the infection, it's a deadly combo.

To prevent WNS, scientists and conservationists have previously developed vaccines and administered them to large colonies in the hibernacula, the places where bats shelter during their dormant season. This method, which involves administering liquid into each bat's mouth, has worked mainly in the eastern United States. Unfortunately, the vaccines are effective only in the short-term, lasting two to four years.

Previously, PNW researchers used this same vaccine. But now, for the first time, some researchers in British Columbia have partnered with the Washington Department of Fish and Wildlife (WDFW) to develop a new probiotic formula specifically for bats in the Pacific Northwest.

Abigail Tobin, a bat biologist from WDFW and part of the team implementing this new method, says the probiotic is a cocktail that consists of four Pseudomonas bacterial strains found on the wings of healthy bats. Tobin says this method, which involves spraying the probiotic into the roosts while the bats are away, is beneficial because it doesn't involve stressing the bats by catching or touching them. "The idea is to apply this probiotic in their roosts during summer and fall before they leave to hibernate. This way, the probiotic rubs off on their bodies when they return to their roosts, allowing them to get the good bacteria on their wings that would stop the fungus. If a bat develops WNS, hopefully it's just a milder, less severe infection, allowing them to survive longer through the winter." However, the researchers aren't sure how long the probiotic will remain effective or how proactively they'll need to reapply the probiotic.

Tobin also mentions that one of the challenges researchers have faced is locating where bats hibernate in Washington State, since some species of bats don't hibernate in huge colonies in accessible places; instead, they're more dispersed, using cliffs, caves, talus slopes, or old-growth trees. However, locating and targeting them during summer was easier, she says, because female bats move into summer colonies to give birth and rear their young, remaining in the roost to stay warm and allow their pups to grow fast and get fat enough to survive the winter.

Abigail says some bats have also adapted to use human-made structures. "So, some bats are in barns, attics, sides of houses, bridges, or even bat boxes," making them easier to locate. The WDFW and researchers in British Columbia are currently in the pilot stage of implementing this new probiotic method on six sites within the state and monitoring the bats' survivorship.

"Bats make up about a fifth of the mammal species on Earth," explains Niki Desautels, president of the board of directors at Bats Northwest, a conservation nonprofit. In Washington, bats represent "a large portion of our wildlife, but most people don't even realize they're here." And their presence impacts us in important, if often invisible, ways. For instance, the U.S. Forest Service says a single brown bat can eat up to 1,000 insects, including mosquitoes, per night. This free pest control prevents crop damage and reduces pesticide use.

Bats Northwest and Woodland Park Zoo have created a new community science program that allows people of all ages to contribute to the conservation of the species. "It can be done anywhere by anyone," says Desautels. "We host meetups to teach people how to recognize bats in the wild, tell them apart from birds, and even use acoustic monitoring devices. A lot of people had no idea they were sharing their neighborhoods with bats."

Dominguez says keeping native trees and shrubs alive is important for bats and migratory songbirds, which use the native foliage to build nests or to find food, such as insects living on the leaves of trees. Renters who can't plant native vegetation can get involved through Seward Park Audubon's BAT program volunteer events, which happen on the second and fourth Wednesdays of each month.

Through BAT's efforts, volunteers have helped scientists track bat activity patterns and gain a better understanding of how local populations are shifting. The program breaks down traditional barriers to scientific engagement; it's open to all and financially accessible, only asking for a suggested donation if an attendee misses their scheduled participation. And Dominguez says the program has welcomed participants from diverse backgrounds and all ages. "These remarkable flying mammals have drawn interest from a broad spectrum of our community," Dominguez says. "Everyone has expressed wonder and affection for bats after sharing our programs!"

Bats have been long misunderstood, feared, called "pests," or simply ignored. The work of researchers, conservationists, and volunteers aims to shift the narrative and also extend the lives of these curious creatures, because these flying mammals, often invisible to us, are quietly balancing local ecosystems. The threat of white-nose syndrome is a silent unraveling of something wild and essential that lives among us. And while the fungus continues its quiet spread, one thing we know now: The bats can't fight it alone.