Indiana myotis once were among the most abundant mammals in eastern North America, and the largest populations hibernated each winter in the caves of Kentucky. One such refuge is know today as Saltpetre Cave. About the time of the American Revolution, it likely housed hundreds of thousands of hibernating bats. By 1983, that number was just 13.
Although declared endangered in 1967, the species has continued to decline – just 380,000 survived in 2001. But now research led by Bat Conservation International points the way to reversing this decline, and Saltpetre Cave may hold the answer.
Protecting critical Indiana myotis hibernation caves from human disturbance is vital – but, clearly, it is not enough. Since some “protected” populations are still declining.
Bat Conservation International has demonstrated that many once-crowded hibernation caves have been altered through Saltpetre mining and commercialization, often centuries earlier, in ways that changed air flow and temperatures, leaving them unsuitable for Indiana myotis. For this endangered species to recover we must find once-key caves, identify historic changes and restore original conditions as much as possible.
Cave restoration has now become the primary focus of Indiana myotis recovery. On March 16, 2005, BCI Founder Merlin Tuttle presented 10 years of data to 70 scientists, conservation biologists and managers at a meeting sponsored by the U.S. Fish and Wildlife Service. Going into the meeting, about 70 percent of those present opposed BCI’s recommended restoration priorities. After seeing the data, however, 94 percent voted to make restoration of hibernation caves the top priority.
A big part of the problem is just determining which caves to protect and restore. In Kentucky’s Carter Caves State Park, Bat Cave, with about 28,000 bats, has been protected as the region’s primary Indiana myotis hibernaculum. The cave, however, provides only marginal hibernation temperatures and is subject to occasional flooding. It's Indiana myotis population has been declining.
The nearby Saltpetre Cave, which was not considered a significant hibernation site, is also in the state park. In 1998, Tuttle, and BCI Cave Resource Specialist Jim Kennedy discovered extensive, but previously overlooked, roost stains on the ceilings. The stains clearly documented past use by hundreds of thousands of Indiana myotis.
Most of Saltpetre Cave’s bats apparently were driven off during the War of 1812, when the cave was mined – and altered – for saltpeter, a component of the gunpowder used until the late 1800s. Some of these displaced bats likely survived, in dwindling numbers, in Bat Cave.
But it is Saltpetre Cave, not Bat Cave, that has potential to house great numbers of hibernating Indiana myotis. Based on BCI’s findings, winter tours of Saltpetre Cave were halted and Indiana myotis numbers had already climbed to 6,088 by 2005. We are now restoring historical conditions at the cave and expect bat numbers to continue their rapid growth.
Bat Conservation International members can read the complete story of the Indiana myotis recovery effort in the Winter 2005 issue of BATS magazine.