Only a few survivors were left after an act of apparently deliberate vandalism in Thornhill Cave, Kentucky this past winter. A small colony of five endangered Indiana Bats and a few Pipistrelles were all that remained of what was recently a population of up to 1,000 bats of various species that used the cave for their winter hibernation. Nearly 4,000 bats hibernated in Thornhill Cave in 1963 when a flood destroyed them. The bats had begun to recolonize the cave by the 1980's, and the last state census in Thornhill Cave included only 80 Indiana Bats.
Discovered in early January, heaps of dead bats were strewn across the cave floor, apparent victims of an intruder with a shotgun. No shells were found, but a number of downed bats were riddled with pellet holes; others were crushed. Nearby on a mud bank was an empty whiskey bottle.
A count of dead bats at the time revealed a tally of 255, but a little over a week later when officials from the Kentucky Fish and Wildlife Department went to investigate the incident, only 188 remained, indicating probable predator removal. The bats unaccounted for from the original known population may have fallen to a similar fate or possibly were chased from their hibernaculum to take their chances in the winter's cold.
Counts in the 1960's showed five Kentucky caves sheltering hibernating populations of 30,000 or more Indiana Bats with a statewide total of at least 330,000. Today, these same five caves harbor a total of only about 49,000 Indiana Bats.
In the early 1960's just one Kentucky cave, Coach Cave (or Hundred Dome) was winter home for at least 100,000 hibernating Indiana Bats, in all likelihood a remnant of an even larger past population. A February 1987 census conducted by Richard Clawson revealed only 250 of that population remaining. In a classic case of human intervention, the cave had been mined for saltpeter beginning in 1812, with portions of it shown commercially since 1860. During the 1960's, a resort and gift shop was built over one entrance to the cave and a heavy steel fence erected over the second entrance. The combination altered the cave's air flow, warming the temperature and making it largely unsuitable for Indiana Bat hibernation.
When the bats attempted to return to their traditional roost in the autumn they were unable to gain access to the cave entrance. With nowhere else to go and the homing instinct strong, they instead clung to the walls of the new building where they reportedly were scraped from their perches. Carted out by the thousands in wheelbarrow loads, Indiana Bats had not yet been declared endangered.
There is a lesson in this, one that cannot be over stressed: bats are extremely vulnerable. Entire populations can be destroyed in single incidents, emphasizing the need for public education and why critical sites must be protected. The vandalism at Thornhill Cave and other deliberate acts of destruction might have been prevented if protective measures had been undertaken sooner The Louisville Grotto of The National Speleological Society has now established a committee to gate the cave and has begun to appropriate funds. Bats are extremely loyal to their chosen hibernation sites, returning to the same ones each autumn. They pass on the information from generation to generation. With only five left of the already small colony of Indiana Bats at Thornhill Cave, it is difficult to assess whether this tiny remnant will be enough to rebuild a viable colony.