Nature Lab

Each month, we highlight research MDC uses to improve fish, forest, and wildlife management.

Resource Science

Thermal Infrared Photography

Resource Scientist Darren Thornhill likes doing technical science, so when his work team at MDC’s Northeast Regional Office in Kirksville needed to test infrared technology, he stepped up. A top infrared camera company doubted whether thermal imaging could help the team detect bats roosting under tree bark, but Thornhill persisted.

“I’d found several scientific studies that used infrared to identify tree disease, especially mold,” he said. Mold holds water, which is cooler than the rest of the tree and therefore creates a clear contrast on a thermal image. “If you can use infrared to figure that out,” he said, “you can use it to figure out where a little mammal is under the tree bark.”

To prove the concept, Thornhill and his team tucked hand warmers under the bark of tree stumps and took thermal images of them. It worked like a charm.

The team then used the camera to find trees where bats were roosting during the day. This enabled them to set up mist nets so they could catch, identify, and attach radio-tracking devices to the bats when they emerged at night.

“The infrared images can’t tell us what species of bat is roosting in a dead tree,” Thornhill said. “But those images can tell us where to focus monitoring and management efforts.”

The federally endangered Indiana bat is a major target of the team’s efforts, but other kinds of tree-roosting bats benefit, too. “Because of threats like white-nose syndrome, which kills bats that winter in caves, it’s important to know what trees host bats and how our management can help them,” Thornhill said.

MDC resource scientists are the first to use infrared imaging to identify the roosting trees of endangered Indiana bats.

Thermal images show where bats roost, improving researchers’ ability to trap, identify, and monitor them. In addition to the federally listed Indiana bat shown here, many Missouri bats are facing disease, habitat loss, and other threats.

Thermal Infrared Photography at a Glance

How it works

• The camera detects and records a heat signature, which is the pattern of the animal’s body heat that emanates to the surface.
• Number of bats it takes to produce a detectable heat signature: 1
• Length of time before a bat’s heat signature appears: 1 minute, 38.8 seconds
• Length of time before a bat’s heat signature dissipates: About 35 minutes
• Number of federally listed bat species in Missouri that could benefit from thermal photography: 2
• Browse more research topics at research.mdc.mo.gov Indiana bat Northern long-eared bat.