Yellowstone Bat Study

Conserving Guardians of the Night Skies

Although most visitors to Yellowstone may not list the bat as a top mammal they would like to see, we should all be glad for these amazing creatures who are hard at work each night. Thirteen bat species can be found in Yellowstone, and each plays an essential role in the health of humans and their ecosystems by helping suppress insects — including those pesky mosquitoes. From the Big Brown to the Spotted, Western small-footed and Hoary, each bat species is an insect-eating machine, the only flying mammal in the world and lives 10-30 years. Let’s hear it for these bat-to-the-bone guardians of the night skies.

There is no greater threat to the survival of bats in North America than the disease White-nose syndrome (WNS). This fungal disease has devastated bat populations in the eastern United States and Canada, leading to regional extinctions of several species. WNS has resulted in the listing of bat species under the Endangered Species Act in the US and the federal Species at Risk Act in Canada. Currently, the disease has not been observed in Yellowstone National Park but it is spreading across Wyoming and Montana.

A coordinated effort among federal, state, and private entities continues to explore ways to slow or halt the spread of WNS in North America. Biologists in Yellowstone are closely monitoring the park’s important bat population and, with your support, will be able to increase their WNS detection resources and capabilities.

Project Overview

The Yellowstone Bat Study team’s white-nose syndrome detection efforts include the following methods:

• Mist net captures allow biologists to collect samples (skin swabs) for WNS detection at roost sites.
• RFID (radio-frequency identification) tagged bats to estimate population size in little-brown bats (species most hard hit by WNS).
• Acoustic detectors deployed throughout the park to record bats’ echolocations.
• Collection, analysis, and storage of all samples.
• Mapping the distribution of bat species.

Update from Yellowstone | October 2026

Pseudogymnoascus destructans (Pd) has been detected at Yellowstone National Park. In July 2026, it was found on 28 little brown bats from two colonies on Yellowstone’s Northern Range. One bat showed signs of wing damage characteristic of white-nose syndrome disease.

Yellowstone biologists sampled the bats as part of white-nose syndrome monitoring that has been conducted since 2019. Pd was also detected in guano and surface samples collected from inside the bat roosts. Sample analyses were performed in Yellowstone’s wildlife health laboratory and confirmed by the Pathogen and Microbiome Institute at Northern Arizona University. These are the first documented cases of the fungus in Yellowstone National Park.

The bats sampled are members of a maternity roost where pregnant females arrive in the spring to raise young and vacate the roosts in late summer. Little brown bats are long lived, and the same female bats return to their maternity roost year after year. Since 2015, hundreds of bats occupying the roosts where Pd was detected have been marked with digital identification tags that track their survival. This monitoring system will allow Yellowstone biologists to understand the impact of white-nose syndrome on Yellowstone’s bat populations into the future.

The fungus spreads mainly through bats, but it can also be carried on gear or clothing exposed to contaminated caves. Yellowstone visitors can aid bats by reporting odd behavior and avoiding direct contact, as bats may carry diseases like rabies.