HANSCOM AIR FORCE BASE, Mass. -- The 66th Civil Engineering Division’s environmental office recently completed its first-ever survey of frogs and its annual survey of bats on the base.
Military installations are federally mandated to balance mission readiness with conservation laws, such as the Endangered Species Act.
Installation officials must identify and monitor threatened or endangered species and avoid actions that could jeopardize those species or adversely modify their habitats.
“The U.S. Fish and Wildlife Service has lists of what threatened or endangered species they suspect to occur in an area,” said Scott Sheehan, installation natural resource manager. “We get those lists and do surveys to determine if those species are present.”
To conduct the surveys, environmental personnel use acoustic recording devices to capture wildlife calls to determine the species present on the installation.
“This is our first year doing wildlife acoustic sampling for amphibians,” said Daniel Robbins, engineering technician. “Frogs are in danger across the country, and since there are several wetland areas on the installation, we did a survey here.”
The frog recording devices were installed from mid-March to July 2026. Analysis of the recordings confirmed a diverse amphibian presence on Hanscom AFB, including wood frogs, spring peepers, American toads, gray treefrogs, North American bullfrogs and green frogs.
“Fortunately, none of the amphibians we’ve identified are on the threatened or endangered species list,” said Robbins. “Bats are a different story.”
The installation began monitoring bats in 2017, and multiple species have been recorded since then. The big brown bat, silver-haired bat, eastern red bat, hoary bat, little brown myotis and federally threatened tricolored bat have all been detected on Hanscom AFB.
Although the recording devices used for bats and amphibians appear similar, the internal technology differs. Bat surveys require specialized microphones capable of detecting the animals’ high-pitched calls.
Three bat recorders were used at locations across the installation where bat activity is known to occur. The devices collect audio data for approximately one week each June.
The recordings are then processed and sent to a laboratory for analysis.
“Bats have unique calls, so the lab runs the recordings through specialized software that can identify them,” said Robbins. “Then we get a report telling us which species are present on base.”
The survey data helps Hanscom AFB environmental officials adjust and improve conservation plans on base and supports environmental efforts by partner agencies.
“We share this data with external partners like the U.S. Fish and Wildlife Service and Massachusetts Division of Fisheries and Wildlife,” said Sheehan. “Some of our wetlands extend into Minute Man National Historical Park, so we work together and share information with them as well.”
Results from this year’s the bat survey are expected later this month. Robbins said he is looking forward to comparing the findings with previous years’ data to determine whether the bat population on the installation has changed over time.
“One thing we learned is there's more to learn,” he said. “These surveys show that we have a lot happening on this base.”