 United
States Department of Agriculture -
Forest Service |
 Southern Research Station200 Weaver Boulevard P.O. Box 2680 Asheville, NC 28802 |
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SRS Researchers Track Indiana Bats in the Smokies
USDA Forest Service researchers tracked endangered Indiana bats during a "bat blitz" held the end of June in the Great Smoky Mountains National Park.
The "bat blitz" was part of the larger All Taxa Biodiversity Inventory, an intense, largely volunteer project to identify all of the life forms in the Park. Susan Loeb and Chuck Dachelet from the SRS Threatened and Endangered Species unit in Clemson, SC -- with student interns Jarrett Drake and Casey Betsill -- took part in the five-day effort to net, identify and tag bat species.
On June 19, the researchers set up two mist nets along Parson's Branch Road, a gravel road that leads out of Cades Cove on the Nantahala side of the Park. One net crossed a ford in the stream that runs along the road: the second, smaller net was set up farther up the road just past another ford, and was positioned to follow the overhanging branch of a large fir. "Bats can detect the mesh of the mist nets," said Susan. "If they have to fly under an overhang, they may not be able to avoid the net."
The net, made of soft black thread, is designed as a series of pockets that gently catch and trap the bats, whose struggling causes them to be held more tightly. It can take some time to unravel the tiny hooked forearms from the web as the bats click or squeak defiance. Bats will bite when scared: the researchers wear thick leather gloves designed for batting baseballs.
During the night of the 19th, the Clemson group caught 10 bats of six different species -- little brown bats, northern long eared bats, red bats, a ferocious beetle-eating big brown, and a tiny pipistrelle. Each bat was identified, examined for parasites, weighed, wing-banded, and returned to the night.
A couple of hours after twilight, the small net yielded an Indiana bat, the endangered species the researchers hoped to find. The Indiana bat was one of the first bat species recognized as endangered by the US Fish and Wildlife Service. Indiana bats hibernate in caves -- some 80 percent of them in nine caves in Kentucky, Indiana, and Missouri -- then migrate to tree roosts in the spring. Declines in Indiana bat numbers were first noticed in the 1960s and documented by winter surveys conducted in the caves.
Even though they mate in the fall, female Indiana bats do not actually become pregnant until spring. Pregnant females migrate to summer roost sites, where they form maternity colonies consisting of 20 to 100 members. The bats roost up under the shedding bark of live or dead trees, bearing only one young. Declines in Indiana bat populations were first attributed to human disturbance in the hibernation caves, but even after caves were gated populations continued to decline. Ecologists began to study maternity roost locations as a possible cause of decline.
In 1999, researchers from Tennessee Technological University (TTU) found an Indiana bat roost in the Nantahala National Forest in western North Carolina. This was the farthest south maternity roosts had been found, and the first report of Indiana bats using conifers for maternity roosts. Ecologists realized that they knew very little about the range and roosting behavior of this forest bat.
Since 2000, researchers from Loeb's unit, in cooperation with TTU's Dr. Michael Harvey and Eric Britzke, have spent a large part of their summers looking for Indiana bats in national park and forest lands in western North Carolina and eastern Tennessee. During the summers of 2000 and 2001, they captured and radio-tagged several male and female Indiana bats and found two large maternity roosts and several smaller ones.
The Indiana bat found on the night of the blitz - a pregnant female - was fitted out with a tiny radio transmitter that the researchers would track the next day, hoping to locate a maternity roost. Though they searched over the next few days, Loeb and Dachelet were not able to find her. They did, however, pick up a signal from a female Indiana bat tagged the previous day by the team from TTU and located her roost in a shortleaf pine snag in the Nantahala area of the Park. After they monitored the roost for a few days, the tagged female moved to a new, inaccessible roost across the Little Tennessee River.
"It is common for Indiana bats to move from roost to roost, carrying their young with them," said Loeb. "Last year we found a roost of about 80 bats in a big snag about a mile away from this year's roost. The snag had fallen down when we found it this year, and we only counted 8 to 15 bats leaving the new roost during the week we watched."
Scientists were surprised when Indiana bats were found in the Park and the Nantahala in 1999: no one expected to find them that far south. Loeb and Dachelet have been looking the past few years in northern Georgia and South Carolina, hoping to find more summer maternity roosts. Understanding the range and maternity roosting behavior of the Indiana bat plays an important role in determining the cause or causes of the species' decline and in managing and restoring the habitat of this endangered species.
For more information: Susan Loeb at sloeb@fs.fed.us or (864-656-4865)
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