A student’s summer spent slogging through Georgia swamps with a flashlight
in hand has shed light on the range and favored shelter of a most secretive
Matt Clement, a graduate student in the Warnell School of Forestry and
Natural Resources at the University of Georgia, wanted to find at least 30
Rafinesque’s big-eared bats, a number approximately equal to previously
documented records of the species in Georgia. He also hoped to characterize
the bat’s roosting habitat.
But Clement’s systematic probing along river bottoms in three management
areas turned up about 565 of these rare mammals with rabbit-like ears. The
research initiated by Warnell faculty member Dr. Steven Castleberry and
funded by the Georgia Wildlife Resources Division and UGA also identified
large, hollow water tupelo trees as key roost sites. Such trees have become
relatively scarce yet can still be found in some bottomlands inaccessible
Clement said the findings greatly expand the known distribution of
Rafinesque’s big-eared bats in Georgia and “deeply refine our understanding
of their habitat preferences.”
The insight can help manage an under-studied species rated as a high
priority in the state’s conservation roadmap, the Wildlife Action Plan,
according to Jim Ozier of the WRD Nongame Conservation Section.
“Too often, the value of big, old trees that develop large cavities is
overlooked,” said Ozier, a Nongame Conservation program manager. “Many
habitat types and components can be managed relatively easily. However,
nothing but time can produce these mature forests.”
Rafinesque’s big-eared bats range throughout the Southeast but are
considered abundant nowhere. Weighing no more than a half-ounce and
measuring 3-4 inches long, they favor forests, flying insects and darkness,
not emerging from roosts until evening has faded to night. Ears more than
an inch long help pinpoint insects through echolocation. The bats emit
high-frequency sounds that bounce off prey and other objects, then
interpret the returning sounds to produce a picture of the surroundings.
Ozier said Clement’s bat discoveries “confirm what we hoped and thought
might be there.”
From May through August, Clement and a helper followed randomly picked,
500-meter transects through bottomlands marked as frequently or rarely
flooded on Tuckahoe Wildlife Management Area near Sylvania, Moody Forest
Natural Area near Baxley and Ocmulgee WMA near Cochran. Each Coastal Plain
site is along a major river. Tuckahoe is on the Savannah River; Moody, the
Altamaha; and Ocmulgee, the same-named river.
Clement checked hollow trees near the transect lines, shining a
million-candle power light into the trees ---- usually through ground-level
openings -- and counting roosting bats. He used a hand mirror for hollows
to small for his head.
He found 97 roosts with Rafinesque’s big-eared bats. Two trees in Tuckahoe
had more than 120 bats each. None of the roosts were in rarely flooded
areas, although some radio-tagged bats flew into those areas, he said.
While still analyzing data, Clement theorizes that water tupelos dominated
as roosts because they tend to grow big, hollow and in frequently flooded
cypress-gum swamps, which provide the protection from logging needed to
reach old age. “It’s the inaccessible sites that support the large hollow
trees,” he said.
Clement is planning more research this summer. But he is already close to
the project’s ultimate goal: Being able to predict where these uncommon
bats with the big ears can be found.