A Halloween Story

Oct. 30, 2018

In Erosion Control magazine, we’ve covered projects at many different types of sites, including lakes and shorelines, agricultural fields, and abandoned mines. All of these areas are on the radar, so to speak, for another type of effort now underway in Tennessee: tracking bats.

The Tennessee Wildlife Resources Agency, the Nature Conservancy, and others are using high-tech equipment to track the endangered gray bat. Although other species the Nature Conservancy has tracked, such as the also-endangered Indiana bat, roost at numerous types of sites, gray bats, native to the southeastern US, are pickier and tend to avoid human-built structures like mines. As far as researchers can tell, 95% of the gray bat population roosts within just nine caves. That makes them vulnerable, but also allows conservationists to focus their efforts on those sites.

Tracking the bats involves fitting them with transmitters. As this article explains, researchers set up harp traps in front of the cave entrances to catch the bats. “We then give the bat a little haircut, apply surgical glue and attach the transmitter,” one researcher explains. The tiny transmitters weigh less than half a gram and fall off by themselves within a few weeks.

Then the difficult part begins. Bats fly and feed at night, and crews track the bats by following the signals from the transmitters—both in cars and in a specially equipped plane—to create detailed maps of their feeding habits. The bats can fly at about 35 miles per hour, and as they cut across water or through areas without roads, keeping up with them can get tricky, but the effort has yielded interesting results. For example, although gray bats were believed to capture insects only over larger bodies of water, the research has shown that about half their nocturnal feeding occurs over small ponds and agricultural fields. The next step will be to track the bats’ migration patterns as they move hundreds of miles to their “winter caves” to hibernate.

The researchers will ultimately use their data to make recommendations about the siting of projects like wind farms and other developments.

About the Author

Janice Kaspersen

Janice Kaspersen is the former editor of Erosion Control and Stormwater magazines. 

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