COLUMBIA, Mo. -- Tours of the Devil's Icebox cave will be limited this summer because of concerns that the number of gray bats that live in the central Missouri cave is declining.
Conservation officials hope the restrictions will allow the gray bats to raise their young without disturbance from human visitors to the cave at Rock Bridge Memorial State Park south of Columbia. Tours allow groups of no more than 10 people to paddle, walk, crawl and wade through the underground passages.
Gray bats give birth from mid-June until about the first week of July, then cluster on the cave's ceiling to share body heat, said Rick Clawson, a research biologist with the Missouri Department of Conservation.
Conservation officials worry that the presence of people might cause the bats to scatter, dissipating the warmth young bats need during a critical period for growth.
After the tours are suspended, biologists will make an estimate of the gray bat population and evaluate the situation. Tours are scheduled to resume Aug. 1 through Oct. 8.
Kathryn McCarthy, an interpretive resource technician at the park, said officials became concerned during the fall tour season when they noticed fewer gray bats.
In recent years, Clawson said, there have been between 9,000 and 11,000 gray bats living in the cave.
"It's possible they were there and we just didn't notice them," McCarthy said. "There are parts of the cave we tend not to take tours into."
Tours of the cave, which is home to six bat species, were also cut back in the fall and winter of 2002 to allow uninterrupted hibernation of the Indiana bat.
Clawson said the Devil's Icebox is the second best environment in the state for the gray bats behind Rocheport Cave in western Boone County. He said it is possible that gray bats in Devil's Icebox have been migrating to Rocheport Cave, which is closed to the public.