the first concrete documentation that Indiana bats summer in Maryland.
The bats were two of six female Indianas agency biologists and a group of
volunteers and wildlife managers trapped as the bats left their winter
hibernating quarters deep in the Hartman Mine (also known as Canoe Creek
Mine) on Canoe Creek State Park in Blair County. The team annually helps
capture and band or mark bats for research and tracking.
"We always suspected Indiana bats were here in the summer, but we didn't
know," explained Dana Limpert, a biodiversity analyst with the Maryland
Department of Natural Resources' Wildlife and Heritage Service. "This is
very significant; it's a whole new ballgame for us. It definitely poses
some unique challenges and great opportunities. We plan to work closely
with the Pennsylvania Game Commission - as well as independently - on this
important front to learn more about these Indiana bats that are spending
their summers in Maryland."
Indiana bats, like most bats, use very different habitats in warm and cold
weather. Winter finds then hanging from the ceiling or sides of a cave or
mine as they hibernate through a time when insects - their only prey -
aren't readily available in the numbers they consume, about 600 per hour.
During summer, bats set up maternity colonies under the exfoliating bark of
trees and snags. They often migrate between their winter and summer
habitats, but not always. At Canoe Creek State Park, Indiana bats banded at
the mine have been recorded taking up summer residence in the nearby Canoe
Creek Church, the state's only known maternity colony.
Until recently, banding was the only way wildlife managers could track bat
migrations from wintering sites to maternity roosts and vice versa, because
telemetry transmitters were too heavy to place on bats - Indianas generally
weigh a quarter-ounce or less. In fact, it was through banding that
researchers were able to link migrating Indiana bats in Michigan to
hibernacula in Kentucky, a discovery that certainly showcased the bat's
potential as a long-distance migrant.
The long trek documented by the Kentucky bats reinforced a consensus belief
that any research transmitter placed on a migrating Indiana bat would have
to be close to weightless and incredibly small to ensure it didn't impede
flight. Holohil Systems, based in Ontario, Canada, managed to build a
state-of-the-art transmitter that met those criteria, and it was used on
bats in this study.
"This transmitter weighs less than a paperclip, but can transmit a signal
up to three miles," said Cal Butchkoski, a Game Commission nongame
biologist who headed up the research project. "It came with a battery life
of 21 days, which we believed would cover just about any Indiana's trek
from wintering grounds to its summer habitat."
Bats were captured in this study - funded by the Game Commission,
Pennsylvania Department of Transportation and the U.S. Fish & Wildlife
Service (USFWS) - when they tried to pass through a metal-framed passage
strung vertically with fishing line at the bat-friendly, gated entrance to
Hartman Mine. The rest of the entrance was blocked off with plastic.
"Bats try to fly through the lines, get caught between them and drop into a
catch bag," explained Butchkoski. "We wanted female bats that weighed at
least 6.5 grams, but preferably 7 grams, to ensure they were physically
capable of flying unimpeded with these transmitters."
Although the Game Commission has been banding bats in Hartman Mine for
about six years, it was unclear where any transmitter-equipped Indiana bat
would go. There was as much a possibility that these bats would head to the
Canoe Creek Church - where Indianas have been found repeatedly in recent
years - as there was that they would take off for parts unknown.
The research team quartered in a cabin provided by the state Department of
Conservation and Natural Resources at Canoe Creek State Park, and began
trapping at the Hartman Mine entrance in the second week of April. During
the first week of trapping, they caught 2,332 bats in the trap, but only a
half dozen were endangered female Indianas, and they never caught more than
two a night. The goal was to take six female Indianas in an evening,
immediately fit them with radio transmitters and release them.
It would have been too expensive - as well as time-consuming - to deploy a
search aircraft and tracking teams in vehicles for only a couple bats.
That's why the team concluded it was best to start all six bats at once,
which meant waiting for the mother lode of hibernation-emerging bats to
wing it for the mine entrance. The limestone mine typically serves as
winter quarters for about 25,000 bats (six species). That mass exodus came
the night of April 17, when thousands worked their way toward the rigged
entrance. Six female Indiana bats were captured, quickly fitted with
glued-on radio backpacks and released.
The researchers managed to keep track of five bats in the air, until one
took off quickly to the east. The ground crew stayed with it at first, but
the bat's speed soon left them in the slipsteam. The aircraft - already
aloft - was radioed to pick up pursuit. First, the bat flew over Lock
Mountain, then Tussey Mountain and Raystown Lake. It crossed Sideling Hill
and the Kittatinny ridges, even Interstate 81. It finally came to rest atop
South Mountain overlooking Caledonia State Park in Franklin County. It was
a straight line run of 60 miles. The next night, the bat left South
Mountain, toured the Gettysburg battlefield and entered Carroll County,
Maryland. It eventually began roosting in a hickory snag 92 miles from
Two other bats were trailed to the south. One of these also entered
Maryland and began roosting near Taneytown in a large shagbark hickory
tree, a textbook site for an Indiana bat maternity roost. The other was
lost on the lower Susquehanna River, near the Maryland state line. Repeated
air and ground searched failed to relocate the bat. Searches were
obstructed by restricted flight zones and interference believed to be
caused by a nearby electrical power plant.
That the researchers were able to track these Indianas to their summer
habitat makes this project a successful one. An attempt two years ago
failed to follow the migrating bats to the finish line.
"We were looking to obtain information about travel lanes, resting areas
and foraging locations used by migrating bats, and were committed to
tracking at least one of these bats to its final destination," Butchkoski
said. "Two bats led us to previously unknown Maryland roosts and continued
to provide information on habitat usage after they arrived and until their
transmitter batteries died.
"Using the techniques we're advancing in Pennsylvania, it's possible for
other states to follow migrating bats and identify, protect and manage
summer roosts. For so long, we've been concentrating on hibernation sites,
because their loss and intrusions into them can be so devastating to bats.
But summer habitat and migration routes are equally important and critical
The demands of this research were exacting on the trackers, both those in
the air and on the ground. Daylight flights were from one to four hours;
night flights, five to six hours. Ground teams worked even longer hours.
Biologists and volunteers frequently pulled double shifts.
"When there was action, we had to stay with it," Butchkoski noted. "And if
there wasn't any signal to follow, we worked intensively to pick up one.
When a project's duration is limited by the life of a battery, almost every
minute counts. Our efforts reflected that urgency. As a result, we tracked
an Indiana bat a record 92 miles using telemetry."
Indiana bats were one of the first bat species in America to be recognized
as endangered by the federal government. They are found sporadically
throughout the eastern United States. Their largest concentrations occur in
Kentucky, Indiana and Missouri. Threats to Indiana bats include loss or
disturbance of wintering quarters, declining summer habitat and poisoning
"Bats are tied to trees," Butchkoski explained. "They need them for
roosting and cover. Indiana bats, in particular, are dependent on
multi-aged forests because they frequently roost under the bark of trees,
such as that found on dead snags and shagbark hickories."
In Maryland, the Department of Natural Resources' Wildlife and Heritage
Service plans to monitor the two trees Indianas were roosting in. Limpert
said they also plan to trap bats with mist nets in the areas the
transmitter-equipped Indianas were using before their batteries died, with
hopes of catching a few more.
"The Pennsylvania Game Commission graciously loaned Maryland coded armbands
and transmitters to place on any Indiana bats we capture, as well as
telemetry equipment," Limpert explained. "If we can net a few and get fresh
transmitters on their backs, it's possible that we can find or confirm a
Pennsylvania is the summertime home to nine species of bats; six of these
species hibernate in caves and mines here. The most common are little and
big brown bats. All are suffering from mounting habitat deficiencies, even
though they now receive more management attention and public compassion
than they ever have. Changing habitat is the most significant problem bats
face. Old structures housing maternity roosts are being lost. Key roost
trees and foraging habitats are being lost to development and certain
timber operations, because their importance to bats wasn't known.
"We're just starting to understand the big picture with bats, and there's
still much to learn," Butchkoski said. "But we do know this much, bats are
still in big trouble. Until we understand what factors are limiting their
survival, they'll remain in trouble."
For more information on the Indiana bat, please visit the Game Commission's
www.pgc.state.pa.us, click on "Wildlife," then choose "Endangered
Species" and the select "Indiana bat."