Over the last two years, U.S. Forest Service biologists have gone high-tech to identify the bats gracing the night skies of Arizona’s Red Rock Ranger District.
But instead of the traditional monitoring method—catching bats in fine “mist” nets—they’re deploying ultrasonic microphones and recorders to listen in to bat talk.
With help from Bat Conservation International, complex computer programs analyze the unique shapes of echolocation calls captured on recordings. These programs have been refined so they can now distinguish among the 23 bat species that could occur in the study area.
So far, this technique has found 20 of those species—including rare ones like the spotted bat. It tends to fly long distances high above the ground so it’s not often caught in nets. But in 2018, the spotted bat’s characteristic calls were recorded in Sycamore Canyon—the first time this bat has been documented in the Verde Valley –and possibly the entire Coconino National Forest. Several less threatened Forest Service Sensitive Species—like Allen’s lappet-browed bats—have been found too.
The highest bat diversity was heard in Fossil Creek— with 15 species, including the largest bat in the country, the greater western mastiff bat. With huge ears extending above its entire face, this oversized bat looks like it’s wearing a giant hat—giving another common name, the bonneted bat.
The acoustical program is conducted on 100-square-kilometer sampling grids across all of North America. It’s set to continue eavesdropping on our bats over the long term, and will likely tell us much more about these fascinating flying mammals.