Bats

Fungus that causes white-nose syndrome in bats detected at Yellowstone National Park

Pseudogymnoascus destructans (Pd), the fungus that causes white-nose syndrome in bats, has been detected at Yellowstone National Park. 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.

 

Duration:

8 minutes, 40 seconds

Resource education film on bats in the Greater Yellowstone Ecosystem.

 

Bat Species in Yellowstone

Thirteen species of bats have been recorded in Yellowstone National Park

• Little brown bat (Myotis lucifugus)
• Big brown bat (Eptesicus fuscus)
• Long-eared myotis (Myotis evotis)
• Long-legged myotis (Myotis volans)
• Townsend’s big-eared bat (Corynorhinus townsendii)
• Fringe-tailed bat (Myotis thysanodes)
• Hoary bat (Lasiurus cinereus)
• Silver-haired bat (Lasionycteris noctivagans)
• Spotted bat (Euderma maculatum)
• Pallid bat (Antrozous pallidus)
• California myotis (Myotis californicus)
• Western small-footed myotis (Myotis ciliolabrum)
• Yuma myotis (Myotis yumanensis)

Behavior

Bats are the only mammals capable of sustained, flapping flight. Active at night, many species use echolocation to find food in the dark; by producing pulses of high frequency ultrasonic sound, they can listen for the returning echoes to navigate. Bats also use lower frequency calls, which can be audible to humans, to communicate with each other.

When not active, bats roost upside down, which makes them less vulnerable to predators and facilitates flight. A special arrangement of ligaments and leg muscles, as well as cranium cavities that pool blood away from the brain, allow bats to hang passively from their perch for months at a time.

To conserve energy during periods of cold temperatures and reduced food availability, bats can enter a state of torpor, which allows them to lower their metabolic rate and body temperature. Most bat species in Yellowstone National Park enter this state during hibernation in the winter and most do not emerge until mid-April.

Diet

All bat species that have been documented in Yellowstone National Park are insectivores, meaning they only eat insects. Because flying demands so much energy, insectivorous bats must eat a lot of insects—in fact, nursing females may eat their own body weight in food each night during the summer!

Bats with long, narrow wings (e.g. hoary bat) are fast, but less maneuverable, and typically forage in open areas. Bats with short, broad wings (e.g. Townsend’s big-eared bat) are slower, but more agile, and typically forage in forested areas. Several bat species in Yellowstone, such as long-eared myotis, pallid bat, and Townsend’s big-eared bat, can hover in order to glean insects off the surface of vegetation.

Habitat & Range

Bat populations can be found in a variety of habitats and use different types of roosts for specific purposes: night roosts provide places to digest meals between foraging bouts, day roosts offer shelter for sleeping, and maternity roosts give females a safe location to raise their young together. Roosting sites provide protection from weather and predators, and can include natural habitats, such as thermally heated caves, as well as artificial structures, like bridges and buildings. Bats often return to the same roosting site each year. Since these sites can be found in historic buildings, this can lead to conflicts between human use and historical preservation plans.

Although some bats migrate long distances for the winter, most western species only migrate a short distance from their summer roosts to their winter hibernating locations, known as hibernacula. Bat activity has been documented in Yellowstone during every month of the year, suggesting multiple bat species remain within Yellowstone over the winter.

Reproduction & Life Cycle

In Yellowstone, bats typically mate in the fall before hibernating. Fertilization is delayed until the female emerges from hibernation, typically giving birth by mid-July. Bats develop and reproduce slowly, which is unusual given their small body size. Most give birth to one pup a year, although larger species in the greater Yellowstone area can have two or more pups at a time. Juveniles typically begin flying in 4-6 weeks, are weaned around 5-10 weeks and become mature in 1-2 years. Of bats that survive their first year, 40–80% survive 7–8 years, while many bats live 10–30 years.

Research suggests that the thermal conditions in maternity roosts, where females raise their young, are important for the reproductive success of little brown bats. Roosts allow young bats to maximize their growth rate, wean, and begin to fly and forage earlier because they use less energy to stay warm.

 

Damage to a bat tail membrane is revealed under UV light.

NPS

Ecological Importance & Threats

Bats are considered indicator species because their distribution and population trends provide valuable information about habitat quality and the overall health of an ecosystem. Bats also help control insect populations, pollinate plants, and disperse seeds, all of which contribute to maintaining biodiversity and healthy habitats.

Few predators specialize on bats, and any encounters are generally opportunistic. Potential predators include owls, falcons, hawks, snakes, and raccoons.

The largest threat to bats in Yellowstone National Park comes in the form of Pseudogymnoascus destructans (Pd). This fungus causes white-nose syndrome, a disease that has caused the deaths of millions of bats across North America by disrupting hibernation and depleting their fat reserves needed to survive winter. It can also cause iritation and damage to the bat's skin. First identified in New York in 2006, white-nose syndrome has since been confirmed in 42 states and 9 Canadian provinces and has been responsible for declines as high as 99% in wintering bat populations. This has led to regional extinctions of several bat species.

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.

 

Resources

Adams, R. A. 2003. Bats of the Rocky Mountain West: natural history, ecology, and conservation. Boulder, CO: University Press of Colorado.

Altringham, J.D. 1996. Bats: biology and behavior. Oxford: Oxford University Press.

Bogan, M.A., and K. Geluso. 1999. Bat roosts and historic structures on National Park Service lands in the Rocky Mountain Region. Final report submitted to the National Park Service, Denver, CO. USGS Midcontinent Ecological Science Center, University of New Mexico, Albuquerque, NM.

Fenton, M.B., and R.M.R. Barclay. 1980. Myotis lucifigus. Mammalian Species Publication No. 142. American Society of Mammalogists. 142:1–8.

Johnson, J.S., J.J. Treanor, M.J. Lacki, et al. 2016. Migratory and winter activity of bats in Yellowstone National Park. Journal of Mammalogy. Advance online publication, 7 November 2016 (DOI 10.1093/jmammal/gyw175).

Keinath, D.A. 2007. Yellowstone’s world of bats: Taking in- ventory of Yellowstone’s night life. Yellowstone Science 15(3):3–13.

 

Bats - NPS Subject Site

Millions of bats live in national parks. In fact, more than 50 unique species of bats live in national parks!

Mammals

All of the park's hoofed mammals migrate across the park to find the best plant growth.