Biologists Megan Zagorski and Jenny Saville in the field at Washington Monument State Park, located on South Mountain.
A field of quartzite boulders extends along South Mountain, the surface sun-baked and lichen-coated, but beneath, Maryland’s tiniest, rarest bats may be roosting in the dark hollows and cracks between rocks, each crevice a potential tiny shelter.
As bats emerge from the rocks at night to feast on insects, biologists are filling up their plate with data. A microphone perched above the boulders captures the echolocation calls of bats, and from that audio researchers can determine which of Maryland’s 10 bat species are present.
Maryland Wildlife and Heritage Service biologists are searching for cave-dwelling species, like the eastern small-footed bat, which have been devastated by white-nose fungus over the past 15 years.
The winged mammals are critical to Maryland agriculture. Not only do they help pollinate our plants and crops, by eating insects they reduce the need for pesticides, saving American farmers billions each year.
During the spring and summer of 2025, biologists collected seven terabytes of data across multiple sites, some seven million minutes of audio. This much data was too much for them to analyze on their own, so they turned to machine learning, or artificial intelligence, to help.
Using SonoBat software that can identify the different wavelengths of different bat species’ calls, biologists can reduce the amount of time they take to analyze the data by more than 50%.
Every bit of data counts to help biologists as they search for answers to stop the decline in Maryland’s bat populations.
Biologists use a pole to elevate a microphone five meters above the boulder field.
In the early 2000s, a fungus that causes the deadly white-nose syndrome in bats began to spread in North America. In 2010, the fungus, originally from Europe, arrived in Maryland and caused more than a 95% decrease in populations of cave-dwelling bats. White-nose syndrome is not deadly to European bats, which likely adapted to the disease over thousands of years. The hope is North American bats will also adapt. Named for the fuzzy white fungal growth on infected bats’ face and wings, in Maryland’s bats, the fungus damages wings and causes bats to wake up more frequently, burning through their fat reserves, which leads to the high mortality rates.
The Maryland Wildlife and Heritage Service is conducting acoustic monitoring to determine where the remaining cave bats are roosting, how the disease is affecting them, and if – fingers crossed – they are recovering. They have found eastern small-footed bats in boulder fields similar to the one surveyed this month, and they hope to find more roosts. Small-footed bats are rock habitat specialists and live in the boulder field all year long.
Maryland researchers are trying to assess what kind of bats roost in the boulder fields, and what factors contribute to use of the boulder fields, such as size, location, or proximity to people. The information they collect will help wildlife experts protect bats and bat habitat across the state.
To place their monitoring equipment, biologists must schlep microphones, batteries, cameras and poles into the field across difficult terrain. And when the time comes, pack everything up and carry it back down the mountain.
Audio recorded outside of prospective bat habitat is analyzed using the machine-learning program SonoBat, which tells researchers if bats are in the area, and if the higher-pitched trills of cave bats have been heard among other sounds and bat calls.
Biologists Megan Zagorski and Jenny Saville hope to publish some findings from their research in the near future as a scientific paper.
A family of woodrats at a suet camera trap.
Machine learning is also used to track another endangered and arguably cute Maryland mammal – the Allegheny woodrat.
Biologists use a motion-activated camera pointed at a block of peanut butter suet to capture any and all critters that approach the suet.
After five nights there are hundreds of images to sort through. Over the course of a season, the cameras capture three terabytes of data. Using machine learning, biologists sort these images into general categories which can be more readily analyzed.
Two porcupines at the suet.
The software has cut down on image analysis time by 60%, the biologists said.
The Wildlife and Heritage Service is conducting a range-wide assessment of the woodrat, visiting sites where woodrats have been spotted in the past. Woodrats are endangered in Maryland, and knowing where populations live can help biologists protect and conserve habitat, in addition to identifying and treating disease.
Anyone who encounters wildlife monitoring equipment on Maryland’s public lands should not touch or interfere with it – it is illegal to tamper with DNR cameras or microphones.
To help bats out, the best thing the public can do is plant a bat garden. Similar to a pollinator garden, bat gardens feature species which will attract insects for bats to feed on. Picking species that support nocturnal insect life cycles is especially important.
Native trees like oaks, hickories, maples, cherries, elms, and willows are great choices. For smaller garden plants, choose goldenrods, asters, coneflowers, and evening-primroses.
