BCI Scholar Christopher Turbill prepares to release a Gould's long-eared bat after attaching a tiny transmitter to its back. Photo courtesy of Christopher Turbill.

Solar-powered Bats

Australian long-eared bats, it turns out, do not behave in wintertime the way scientists expected them to. BCI-sponsored research finds that the little, insect-eating bats hibernate in surprisingly unprotected roosts and depend on the solar power of an occasional sunny day to get them up and ready for an evening's hunt.

Christopher Turbill, a Bat Conservation International Scholarship recipient from Australia's University of New England, tapped into new technology to locate hibernating bats and record their fluctuating temperatures through the winter. He glued tiny, temperature-sensitive transmitters to bats that he captured and released, then radio-tracked them to their roosts.

Long-eared bats typically roost under peeling bark or in shallow tree crevices during the summer, Turbill says. “We expected that in winter they would shift to better-protected and well-insulated tree roosts and hibernate in a similar way to cave-dwelling bats.”

Instead, he found that even in winter, the bats roost under bark or in shallow crevices, although generally on the sunny side of the tree. The bats' skin temperatures during winter torpor, as recorded in these roosts and transmitted to remote data-loggers, can vary daily by as much as 32.4 degrees F (18 degrees C).

The data suggest that these mammals, after being warmed by the sun, can more easily rouse themselves after as much as two weeks of continuous torpor, enabling them to hunt insects that abound on warm winter evenings.

Turbill studied lesser long-nosed bats, Gould's long-eared bats, and chocolate wattled bats. The transmitters were attached to captured bats with nontoxic glue and fall off in about five weeks.

To support Bat Conservation International's Graduate Student Scholarship Program, please contact Andy Moore at amoore@batcon.org or (512) 327-9721.

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