White-Nose Syndrome

White-nose Syndrome (WNS) is a fungal disease that has killed millions of North American bats in the past decade. WNS disrupts natural hibernation cycles, causing bats to die from the disease during winter. The fungus, Pseudogymnoascus destructans, often called “Pd,” grows in cold, dark, damp places where bats hibernate, causing a white fuzz on their faces. The fungus rouses bats from their torpor, causing them to burn the fat they need to survive the winter and decimating entire populations of bats. WNS currently impacts bats in 40 states, including Texas. There’s no known cure, although scientists are studying how it spreads in the hopes of controlling it.

Pd was first detected in Texas in 2017. Texas has numerous cave systems and cave-hibernating bat species, such as cave myotis (Myotis velifer) and tricolored bats (Perimyotis subflavus), most vulnerable to WNS.

“Tricolored bats have been proposed to be listed as federally Endangered due to dramatic population declines from WNS,” says Bat Conservation International (BCI)’s Texas-based Conservation Research Coordinator Sarah Stankavich. “WNS and the associated fungus is continuing to spread across the central and western United States and Canada; not only is it spreading geographically, but new bat species will be impacted as WNS moves into new regions.”

Stankavich monitors and implements BCI’s research projects throughout the state and has worked with BCI in Texas for one year.

“Texas is in the intermediate area for WNS, meaning the fungus and disease have been confirmed in some hibernating populations but not all, and the impact on bats seems to be happening more slowly here than in the East,” she says. “This means we have an opportunity in Texas to study how WNS may act differently in warm climates and that gives us the chance to research questions we wish we had answers to when WNS was first invading the East.”

Stankavich and her team visit Texas cave sites four times yearly to count how many bats are present from each species. They monitor Pd on bats and hibernacula substrate, where the fungus can persist even in the absence of bats. The team also records any signs of WNS, such as bats with visible fungus or the presence of dead bats. Sensors inside the caves record hourly temperature and humidity readings, and acoustic detectors outside the cave entrances help determine the time of year the bats use the caves.

BCI has been monitoring WNS in North Texas over a decade, and the Pd progression is delayed compared to East and Midwest bat populations. However, in 2022, WNS caused a mass mortality event of Myotis velifer in central Texas.

“We are trying to understand the key factors that allow Pd to invade and become an epidemic at Texas sites,” says Tina Cheng, Ph.D., BCI’s Director of White-nose Syndrome Research. “If we can understand how this system works, we may be able to manage the disease.”

BCI scientists are currently working to understand what makes some bat populations more vulnerable than others. They hope to develop data-driven conservation strategies that will benefit bats in Texas and beyond.