NPS works to protect bat populations while restoring historic structures at Minidoka National Historic Site

by Jennifer Jones, National Park Service

The National Park Service (NPS) is taking action to ensure that bats that frequent the Minidoka National Historic Site can still use the area while restoration of the historic Block 22 Barrack, Mess Hall, and Root Cellar buildings is underway and after the work is completed. 

A recent study documented the presence of all 12 Idaho bat species at the Minidoka National Historic Site. The study was conducted in 2025 by Anna Saunders, a Utah State University student. The goal of the study was to create a list of bat species found in the park and to assess bat activity levels in historic structures where restoration work will begin this spring. 

“This study is important because it provides park managers park-specific data to develop strategies to mitigate the impacts of bat habitat loss that may occur as a result of the restoration work,” said Todd Stefanic, wildlife biologist for the southern Idaho parks, National Park Service. “This is especially relevant to the root cellar, which currently has many openings that bats can fly in and out of that will be closed as part of restoration.”  

During the study, acoustic monitors were set up at three different locations at the Minidoka National Historic Site to record bat echolocation calls from 30 minutes before sunset to 30 minutes after sunrise between June 1 and August 8. The acoustic monitors detected the presence of all 12 Idaho bat species - Western small-footed myotis, big brown bat, little brown myotis, California myotis, Yuma myotis, long-legged myotis, silver-haired bat, hoary bat, long-eared myotis, Townsend’s big-eared bat, fringed myotis, and pallid bat. Several are classified as “species of greatest conservation need” by Idaho Fish and Game. 

NPS staff have already started taking action to protect bat populations from the impacts of habitat loss from the restoration projects. This includes mounting “bat boxes” on the east side of three buildings throughout the park. These small wooden structures provide bats with a protected place to roost during the daytime and potentially to birth and raise pups.

NPS Employee, April Felkner, installs a bat house. Friends of Minidoka volunteers helped to install additional bat houses. Photo Credit: NPS.

Bats are critically important to Idaho agriculture as they consume insects considered to be agricultural pests, such as leafhoppers, moths, and beetles. A single bat can eat thousands of insects per night, reducing the need to apply chemical pesticides to crops. A 2011 study estimated bats provide about $313 million annually in pest-control benefits to Idaho agriculture. 

However, bat populations in Idaho and throughout the world are declining rapidly as they face growing threats from habitat loss and disease. Mitigating potential bat habitat loss resulting from restoration of historic structures at the Minidoka National Historic Site has taken on new urgency as Idaho Fish and Game recently announced that white-nose syndrome has been confirmed in Idaho bats for the first time. White-nose syndrome has killed millions of bats in North America since it was first detected in 2006. 

“Anything we can do to help bats is important,” said Stefanic. “If implementing a project results in loss of existing habitat, we need to provide them with something else.” 

The new study is a good start as prior to it, there was very limited data available on bats at the Minidoka National Historic Site. However, additional research is needed to determine how bats are actually using the park. According to Stefanic, preliminary analysis of the data indicates that many bats, which can fly ten miles per night while traveling between feeding sites, are passing through the park, but not necessarily residing there. He plans to continue studying how bats are using the Minidoka National Historic Site.