By Merlin Tuttle
Long Cave, in Kentucky, like many others, has a long history of human occupation with little record of prior use by bats. It was mined for saltpeter, a key ingredient of gun powder, during the war of 1812 and was subject to commercial tourism, probably beginning at about the turn of the century, ending by the 1930s.
Huge passages trapped cold air and remained cool year-round, offering major opportunities for bat hibernation. Roost stains from past bat use were widespread, and the cave clearly had potential to shelter millions. As recently as 1947 some 50,000 bats, presumed to be largely the now endangered Indiana myotis (Myotis sodalis), continued to return in winter. Nevertheless, entrance barriers built to exclude non-paying tourists, increasingly restricted air flow, eventually culminating in a concrete wall and a nearly solid door.
The bat population plummeted, leaving only roost stains as evidence of extraordinary past use. By the time that Mammoth Cave National Park was established in 1941, few bats could be found in the park’s caves, and those that remained weren’t yet recognized as either important or endangered.
By the early 1990s, as characteristic bat roost stains began to be recognized, the huge historic importance of several of the park’s caves began to be suspected. Cave Resource Management Specialist and Research Coordinator, Rick Olson, invited me and several colleagues to lead an investigation. We quickly found unmistakable evidence, of past use by at least 9-13 million bats, perhaps more than twice that many, mostly endangered gray (Myotis grisescens) and Indiana myotis.