Going batty!

Researchers study the foraging habits of gray bats at Crystal Cave

Dr. Tom Risch, right, chairman of the Biological Sciences Department at ASU and professor of biological sciences, prepares to place a transmitter on the back of a gray bat with the assistance of Arin Vann, research technician.
Dr. Tom Risch, right, chairman of the Biological Sciences Department at ASU and professor of biological sciences, prepares to place a transmitter on the back of a gray bat with the assistance of Arin Vann, research technician.

At dusk, the sky above Crystal Cave in Bella Vista is filled with gray bats as they leave for their nightly forage.

But not on a recent Tuesday.

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The Weekly Vista

Patrick Moore, the graduate student who is heading the bat foraging study, leans over the cave entrance to talk to researchers who retrieve the bats from the harp trap.

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The Weekly Vista

Working from two stations, researchers place transmitters on the backs of 25 gray bats. Working at the stations are, from left, Caitlin Campbell, research biologist; Patrick Moore, graduate student who is heading the study; Dr. Virginie Rolland, assistant professor of wildlife; Dr. Tom Risch, chairman of the Biological Sciences Department at ASU and professor of biological sciences; Arin Vann, research technician; and Blake Sasse, non-game mammal biologist for the Arkansas Game & Fish Commission.

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The Weekly Vista

With the hair trimmed on her back, a gray bat is about to receive a transmitter. A silver identification band can be seen on wing at the right.

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The Weekly Vista

Caitlin Campbell, research biologist, blows on the back of a bat to help the glue dry prior to the placement of the transmitter.

The entrance of the cave -- which is located in the middle of Brompton Courts off Chelsea Drive -- was blocked so researchers, led by professors and students from Arkansas State University, could trap the bats to band and for 25 lucky ones to receive a transmitter to track their movements.

ASU is in the second year of a two-year Arkansas Game and Fish Commission grant to study the foraging habits of the bats, which have been an endangered species since 1976. Part of improving the population is to understand their foraging habits.

The job of tracking the bats once they are fitted with a transmitter falls on Patrick Moore, a graduate student at ASU who is using the study for his master's thesis.

The researchers set up a tarp that covered more than half the entrance to the cave, then set up what's called a harp trap to cover the remaining opening. The bats fly into the trap, which looks much like a thin-stringed harp, then fall into a cloth container where they are retrieved by the researchers.

Crystal Cave, which has about 5,000 bats, is a maternity cave with mostly breeding females and their young, Moore said. The bats like the cave because it is warmer and allows the young to grow faster.

Other caves are bachelor caves. There are also winter caves where both species will hibernate in cooler temperatures, said Dr. Tom Risch, chairman of the Biological Sciences Department at ASU and professor of biological sciences. Risch was also on hand at the cave, along with Dr. Virginie Rolland, assistant professor of wildlife. Nine researchers were working on a Tuesday night, including three consultants from an East Coast company who came to learn more about the gray bat.

In getting the bats ready to host the transmitter, the hair on the back of the bat is trimmed, glue is applied and then the transmitter is placed. Generally the transmitter will stay on the bat's back for eight to 14 days.

Once the transmitters are glued on the backs of the 25 bats and they are released, Moore and pilots and support staff from the Civil Air Patrol squadrons in Rogers, Jonesboro and Fort Smith will track the foraging bats, he said.

Moore spent 13 days flying above the Bella Vista area from 9 p.m. to 3:30 a.m., he said. The Cessna 182 was equipped with a highly directional antenna on each wing which was hooked into his receiver unit. He sometimes used two sets of earphones at the same time to pick up the beeps.

He zeroed in on the beeps, then used the signal strength to monitor the locations of the bats.

In last year's study in the eastern part of the Ozarks near Batesville, the bats foraged out 12 miles on average. Some went out 25 miles, Moore said.

Other researchers have tried to follow the foraging habits of the bats from ground level, but were unsuccessful, said Risch, who has been studying bats in Arkansas since 2003 when he came to ASU.

"With the help of CAP and the Arkansas Game and Fish, we have been able to track them from the air," he said.

The bats' transmitters emit a signal that is picked up by a scanning receiver in the plane flying 2,500 feet above the ground, said Moore. The bats themselves fly 6.5 feet off the ground.

"They forage above the water," Moore said. "They can go anywhere, following a creek like a roadway. Flying left then right to their forage locations."

The researchers donned latex gloves to work with the bats, whether to band or place a transmitter, to protect the bats from white-nose fungus, a fatal disease which has decimated bat colonies.

"However, gray bats have not been profoundly impacted by the fungus," Risch said. Crystal Cave hasn't had any instances of white-nose fungus, which has killed 7 million bats, he added.

Even in their winter hibernation, gray bats move around a lot in the cooler cave, which may be why there isn't as much white-nose fungus among gray bats, he said.

Another killer of bats is wind energy, Risch said.

More than 700,000 bats have been killed by wind-powered electric generators. The bats seemed to be attracted to the vibrations of the windmills, he added.

"Bats are the most misunderstood animal," said Risch, who noted that one out of every five mammals is a bat. "They offer tremendous benefits."

Besides eating mosquitoes, they are predators of agriculture pests, both farm and in the forest, he said.

There are 1,300 species of bats, said Risch, who studies bats around the world. Near the equator there are more than 200 species. The largest areas of bat populations are Central and South America.

Risch said Arkansas does a great job of protecting its bat population. Crystal Cave, for example, has a fence that keeps the bats from being disturbed and keeps people from going in the cave and spreading disease.

Blake Sasse, nongame mammal biologist for the Arkansas Game and Fish Commission in the Mayflower office, said the grant will help the commission see when and where the bats are foraging on the main waterways around Bella Vista and Beaver Lake. The commission also hopes to study where the bats spend the winter.

Hopefully this research helps ensure that as the skies darken over Bella Vista, gray bats continue to fly out of Crystal Cave for their night's forage flights.

NAN Profiles on 08/02/2015

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