|A big brown bat is entangled in nets strung up by a bat|
research company on Chouteau Island on June 12, 2012.
The bats started flying into the nets shortly after dark.
"They're used to their regular routes, and we hope to catch them not really paying attention to the fine detail of our nets," said Janet Tyburec, a biologist for Bat Conservation and Management Inc. of Carlisle, Pa.
Tyburec, 45, and field technician Brenna Long, 27, are helping the Army Corps of Engineers study the Indiana bat, an endangered species.
The bat, which hibernates in caves in the winter and summers in forested areas, makes its home most frequently in the central United States, where white-nose syndrome has become a concern.
The disease has killed more than 6 million bats in four Canadian provinces and 19 U.S. states. First detected in 2006 in New York's Adirondack Mountains, it's unclear how the fungus got to North America. One possibility is that it hitchhiked here on the clothing of tourists.
In April, the disease was documented in Missouri — the first confirmed case west of the Mississippi River.
"We haven't had white nose in the Indiana bat's range for many years yet, so we don't know what their declines are going to be like," Tyburec said.
Other factors related to the mammal's habitat, though, have led to a significant population drop. In 2009, the U.S. Fish and Wildlife Service estimated the Indiana bat population at 387,000, less than half as many as when the species was listed as endangered in 1967.
Corps officials hope they can help the bat's numbers rebound by tracking their summer locations on corps property. After spending time on Chouteau Island, which lies between the Mississippi River's main channel and the Chain of Rocks Canal, they planned visits to sites in Pike County, Mo., Calhoun County, Ill., and Jersey County, Ill.
"Let's say we find the bats in a nice cottonwood patch, since they like to roost under the sloughing bark," said Ben McGuire, 26, a wildlife biologist with the corps. "If the cottonwood patch is fairly young, we can go in there and do some supplemental plantings so there's a diverse community for them."
IT'S BAT TIME
At 8:45 p.m. one day last week, just before dark, Tyburec and Long used pulleys attached to metal poles to hoist three braided nylon nets 27 feet high. They positioned them between two ponds in a field of high grass and poison ivy about 50 yards from a station where they would process the bats.
"Bats like to drink out of pooled water, not rushing water," Tyburec said. "And one of the first things they do every night is go get a drink."
The women and McGuire went back to sit on the tailgate of an SUV or in camp chairs and wait. About a half hour later, head lamps showing the way, they found several bats ensnared in the nets, although the species wasn't the one they sought. These were big browns, a majority of them lactating females that were silent except for a gnawing sound as they tried to free themselves.
At first glance they looked more like a dead leaf than a toothy predator. But as Tyburec and Long untangled them, they fluttered and showed their fangs, clicking a signal that sounded a little like a dolphin, which also uses echolocation to navigate.
As the women put the bats in cloth and paper bags, they fell silent.
At the processing station, Long pulled on fresh surgical-type gloves over thicker ones as she grabbed the bats out of the bags to measure their forearms, their weight and record their gender and reproductive conditions before releasing them.
Long changed the gloves for every bat in case any of them had been infected with white nose; she didn't want to cross-contaminate them.
Tyburec wrote each bat's information in a log, noting which net they had come from. She took down the weather conditions and the GPS coordinates, too, in case they wanted to return to the exact location.
In addition, she used a device to record the high-frequency calls of any bats in the area. If the calls were audible, they would have been as loud as a triggered smoke detector, she said.
Tyburec and Long said they previously had been bitten. As a precaution, they had gotten pre-exposure rabies shots and regular boosters. They wouldn't have to seek immediate medical attention if they got bit that night.
"Rabies is always fatal, so taking a risk is just not worth it," Tyburec said.
FRIENDS OF THE ECOSYSTEM
Despite negative stereotypes, bats are important to the ecosystem, Tyburec said. They are efficient predators of insects, and worldwide they pollinate flowers and disperse the seeds of hundreds of plants.
Their numbers have not rebounded, even after the closing of some of the caves where Indiana bats hibernate, Tyburec said.
"A lot of the caves we were protecting for them didn't have the ideal temperature range they needed to hibernate because they'd been commercialized," she said. "The entrance dimensions and passage dimensions had been changed, and that dramatically affected the air flow in these caves."
Some populations showed a slight uptick after efforts were made to restore the caves to their historic sizes, but then white-nose syndrome arrived.
The fungus is visible on exposed parts of the skin and is often seen on the muzzle of the bat. Tyburec said she and other biologists who study bats check the wings to see whether there's any scarring from the disease. The fungus is not active now; its growth is optimal between 43 and 53 degrees, she said.
In addition to these challenges, Indiana bats have been losing summer habitat because of urbanization and forestry practices. A slow reproductive cycle is compounding the problem, Tyburec said.
In general, bats only have one baby a year. The young take about two years to reach sexual maturity, and first-year young have about a 50 percent mortality rate.
"These populations are never going to recover in our lifetime," she said. "It's really tough to be a bat."
By the time Tyburec and Long called it quits at 2 a.m., they had bagged 28 bats and four different species — the big brown bat, the red bat, an evening bat and a hoary bat.
No Indiana bats were captured or recorded on the listening device, although the call of another species, the tri-colored bat, was detected. Tyburec didn't seem rattled.
"This is a really urban area, and we're going to be moving to some more rural forested type areas, so hopefully we'll be encountering them soon," she said.
Since then, the bat hunters caught four of the endangered species, two of which were lactating females, so they had young nearby. The biologists recorded their findings, banded the bats and set them free.