Hundreds of bats in about 10 different species make the Wappapello Lake area their home.
Using echo-sounding, they zero in on flying insects for a quick meal after sleeping during the day.
One of their favorite flight corridors is along the East Fork of Lost Creek, a spring-fed creek about 10 miles north of the lake.
And this is where researchers from Southern Illinois University at Edwardsville set up traps to catch bats from Aug. 17 to 22.
The reason: Last year during the first year of a five-year plant and wildlife survey being conducted for the U.S. Army Corps of Engineers at Wappapello Lake, researchers found two kinds of bats that are on the federal list of endangered species, gray bats and Indiana bats.
"Gray bats had never been found this far east in Missouri," said James Gracey, U.S. Army Corps of Engineers natural resource specialist at Wappapello.
The bat-trapping project was headed by SIU associate scientist Tim Carter.
Carter said Indiana bats had dropped in numbers from 6 million in the 1960s to an estimated 380,000 today.
"Seventy-five percent of these bats hibernate at nine locations. Which make them very vulnerable," Carter said.
Gray bat numbers are currently at 3.5 million. They are also vulnerable because they also have only a few locations for hibernating. Both species range over a third of the country, mainly in the Southeast and East.
Most of the 40 bats retrieved the night of Aug. 10 were red bats, the predominant species in the area. They also caught five other bat species, including two grays.
Carter, who is immunized to protect himself from rabies, glued a tiny radio transmitter with an 8-inch-long whip antennae to the back of one of the grays and turned it lose. The second gray got loose from the net before it could be caught. The tiny transmitters weigh about one-fifth of a penny.
Carter said transmitter signals can be detected from a half-mile to three-quarters of a mile and that batteries for the transmitters last about 12 days.
Gary Stilts, U.S. Army Corps of Engineers manager at Wappapello, said the corps is paying around $60,000 a year for the five-year plant, bird, reptile, amphibian and mammal survey.
The survey will take in 45,000 acres. The land mass runs north to just outside Sam A. Baker Park, west of Greenville.
"It's hard to manage if you don't know what you've got," Stilts said. He said survey results would help determine future management practices.
The researchers had planned to locate roost sites of the two species by Aug. 16 but were unable. The team determined the bats were probably in their breeding season and therefore would be hard to track due to erratic behavior.
"They plan to come back in the spring when the bats are having their young," Stilts said.