South Carolina Endangered Bats are Being Helped by 16-foot-tall Concrete Roosts

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Sixteen-foot-tall concrete bat roosts put in place around South Carolina using a State Wildlife Grant are designed to help the state-endangered Rafinesque’s big-eared bat but may also be providing habitat for some other uncommon bats as well as chimney swifts.

Rafinesque’s big-eared bats, a state endangered species, require large open structures for roosts, and natural roosts tend to be massive hollow trees now in short supply, according to Mary Bunch, biologist with the S.C. Department of Natural Resources (DNR) based in Clemson. At Silver Bluff Audubon Center & Sanctuary in Aiken County, a colony of Rafinesque’s big-eared bats had been using an abandoned house, but the structure is in disrepair and slowly collapsing. In anticipation of the loss of that roost site, DNR erected an alternate concrete bat roost nearby.

Input for the design of the Silver Bluff concrete tower was received from the Southeastern Bat Diversity Network and Bat Conservation International. The cylindrical concrete roost is 4 feet in diameter and about 16 feet tall. A roughened interior helps improve roosting ability, and the middle section of the roost has a triangular entrance hole with a maximum width of 24 inches. The first roost was installed on March 15, 2011, and by May, it was being used by a single Rafinesque’s big-eared bat, with use expected to increase as the building roost deteriorates. The Silver Bluff roost was also used by a pair of chimney swifts during the most recent nesting season, according to Paul Koehler, Silver Bluff director.

Since the erection of the Silver Bluff bat roost, three additional concrete roosts have been put in place: 1) at Hamilton Ridge Wildlife Management Area in Hampton County; 2) at Ashmore Heritage Preserve in Greenville County; and 3) on Sassafras Mountain (the state’s highest peak at 3,583 feet) within the Jim Timmerman Natural Area at Jocassee Gorges. A Rafinesque’s big-eared bat was recently reported at the Hampton County roost, along with a fair amount of droppings.

The two mountain roosts, at Ashmore Heritage Preserve and Sassafras Mountain, were modified to include wooden crevices that will appeal to other colonial cavity roosting bats, such as Northern long-eared, little brown, tri-colored and big-brown bats.

MST Concrete of Central built and delivered three of the bat roosts. “MST Concrete’s enthusiasm to work with us on the design really helped us get the project going,” Bunch said.

Funding for the roosts was provided by the State Wildlife Grants Program (Pdf file), which provides federal dollars to every state and territory to support cost-effective conservation aimed at preventing wildlife from becoming endangered. Congress created the program in 2000. Funds appropriated under the State Wildlife Grants Program are allocated to every state according to a formula based on each state’s size and population. The source of funds for this program is offshore oil leases.