The Bats of Craters of the Moon: Cave Roosts, Hibernation and White-Nose Syndrome

The hundreds of caves at Craters of the Moon give bats places to roost, raise young and hibernate, and bats are a vital part of life underground and above. Whatever their reputation, the bats here eat mainly insects, helping keep mosquitoes and crop pests in check.

Bats are a common sight after sunset at Craters of the Moon. NPS photo

Eleven species have been documented in the park, and up to five more may occur — species recorded close by, or whose known range includes the park.

What the surveys found

Park biologists and researchers are working out which bats live here, which hibernate or raise young here, and which of the park's caves they use.

• 2013–2017: a five-year study confirmed 17 hibernation caves (hibernacula). Over half of the caves judged suitable were used in at least one of the five years. 75% of hibernating bats were Townsend's big-eared bats; next came the western small-footed myotis.
• 2018: a study of Townsend's big-eared bats found that 64% of known and potential maternity roosts in southern Idaho were inside Craters of the Moon.
• 2019: biologists monitored 20 caves during the maternity season — installing temperature and humidity loggers before the bats arrived, collecting guano, and placing acoustic detectors at entrances, since many species look alike. Two nights of exit counts helped estimate colony sizes. They confirmed three known maternity colonies of Townsend's big-eared bats and western small-footed myotis, and found three new ones, likely western small-footed myotis.

Biologists keep a close watch on the health of the park's bats. NPS photo

Who lives here

Hibernation sites for some species remain unknown because surveys are few and many bats are hard to identify without handling them.

White-nose syndrome

White-nose syndrome has devastated the little brown myotis and other species in the eastern United States and Canada, killing millions of bats since 2006, with death rates of 90% or more. It is caused by a cold-loving fungus, Pseudogymnoascus destructans (Pd), that attacks bats in hibernation, and it lives underground whether or not bats are present. The fungus is widespread along the West Coast and was confirmed in Idaho in 2022, but not yet at Craters of the Moon.

Pd does not affect people, but it can survive on surfaces for years and travel from cave to cave on clothing and gear — ordinary washing doesn't kill it, and peroxide mats clean only the soles of footwear. So:

Nothing that has ever been worn in any other cave, cavern, mine or underground space may be worn or brought into the caves at Craters of the Moon.

The safest practice is a completely separate set of clothing for each underground space. See white-nose syndrome and cave permits.

The little brown bat is common in the park, and its fate is a real concern: petitions to list it urgently under the Endangered Species Act have been sent to the U.S. Fish and Wildlife Service, citing studies that gave a 99% likelihood of the species' regional extinction by 2026.

Learn more

Helping bats at home. Image from the National Park Service's page on the park's bats

The battle for bats: white-nose syndrome and how to help stop it. Image from the National Park Service's page on the park's bats

"Seeing" in the dark: how bats navigate and hunt by echolocation. Image from the National Park Service's page on the park's bats

Sources

Based on "Bats at Craters of the Moon," National Park Service, citing Call and others (2018) and Munts (2011); a work of the United States government in the public domain. The source's scientific names Lasiurus cinerus, Lasiurus blossevilli and Parastrellus Hesperus are corrected here.