Published: February 10, 2007 11:42 pm

Lighting the Way

Carter Caves research model in repopulating Indiana bat

CARTER CAVES STATE RESORT PARK — Jim Kennedy taps a few keys on his laptop, and the screen fills with lines.

Symbols show towns and roads. Ticks mark latitude up one side and longitude across the top.

Blue circles pinpoint cave entrances, with hundreds dotting an electronic landscape of Kentucky and surrounding states.

“We’re looking at caves that are likely Indiana bat caves ...,” he says.

Complex, multi-level ones like a vertical shaft near Somerset that’s now being cleaned of accumulated trash.

Or grottoes anywhere from Indiana’s karst plateau to here in Olive Hill, all monitored for the cold air the endangered species like best.

Or the booming passages that snake through West Virginia’s lengthy limestone, many mined in the 1800s for the gunpowder ingredient of saltpetre.

“They kind of fit the model we’re looking for,” says Kennedy of Texas-based Bat Conservation International.

He’s a biologist who is as comfortable in a cave helmet wading through bat guano as he is scrolling around computerized topo maps.

And he’s on a mission to bring attention to these caves, because nobody’s counting bats in those, or doing anything, he says.

“Yet they could be very important to the eventual recovery of the species.”

But how? How can just finding the right cave save a mammal that weighs less than a few pennies from extinction?

To answer that, Kennedy scrolls his map back to Kentucky, to Carter County, to Carter Caves State Resort Park. Where a single dot marks its historic Saltpetre Cave.

“We’ve looked at 60 or 70 (caves) in Kentucky,” he says. “Six or seven, we think, are ones we can do something with ... and Saltpetre was the poster child.”

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Saltpetre Cave is an excellent example of a cave that was once a “bastion of survival” for hibernating Indiana bats, wrote Kennedy and Dr. Merlin Tuttle, founder of the nonprofit BCI, in a recent three-year strategic plan for the species’ survival.

In 1997, researchers scoured 20 years of temperature and population data gathered at caves where most Indiana bats hibernate. They found that in caves where winter temperatures ranged from 3-7.2 degress Centigrade, the bat population grew by 97,339. In caves warmer or colder, bats declined by 185,117.

“Part of the loss, we feel, is a loss of winter roosts,” Kennedy said.

That is, the ideal caves of the past had been changed physically, such as through mining for saltpetre and commercialization, which changed the airflow, which changed the temperature, and that changed the “microclimate” and made the caves less suitable.

All of which means fewer bats now live through the winter to bear offspring. There are only an estimated 400,000 remaining, where in the early 1800s millions could still be found in single caves, biologists say.

To further test the hypothesis, Kennedy and others began a rangewide study in 1998 to document temperatures at 15 favored Indiana bat caves in six states, including Bat Cave and Saltpetre Cave at Carter Caves.

They installed “dataloggers” that record temperatures every three hours over a year. At the same time, they looked for past “roost stains” on rock caused by the body oils and excrement of hibernating bats.

They found that Bat Cave’s temperatures were too often too cold and too warm, even though it harbors 20,000 to 30,000 bats each winter — it’s one of the state’s major Indiana bat roosts, but numbers have declined since it was first gated in the 1960s.

At Saltpetre, Kennedy found a much more stable, although not quite optimal, temperature; and enough roost staining to suggest hundreds of thousands of bats once used it, that it might perhaps be “the” bat cave here.

“It really wasn’t ever thought of as a bat cave,” he said. “But what we know about Indiana bats is they are really susceptible to disturbance ... since they’re trying to live through the winter on what fat they’ve stored up.”

So, beginning with 1998-1999’s winter months, the Kentucky Department of Parks agreed to cancel commercial tours at the cave.

In the first two years the hibernating population grew dramatically from just 475 to 1,225, and to more than 3,000 two years after that.

Then in 2003, BCI, state wildlife authorities and volunteer cavers descended on Saltpetre to replace an aging bat gate at its entrance. More “bat friendly” horizontal steel bars were placed around the tour house, and the sides were opened to allow better airflow into the cave.

Additionally, open-air pits near the entrance were cleaned and an “air dam” door installed in one of the cave’s passages to offset historic changes in the caves environment -- the need for gunpowder ingredients during the War of 1812 led to extensive excavation of the cave’s dirt, which changed passage heights and airflow.

The work’s result? Cave temperatures stabilized even further, in favor of the bats’ preferred climate.

And, at the next two-year count, in 2005, the population doubled to 6,088. This year, it increased to 6,899.

“Indiana bats were once more widespread than they are now,” Kennedy said. “Some have been forced out of caves because of human disturbance ... or the uses the caves have been put to in the past such as saltpeter mining, commercialization and so on, which have made physical alterations to the caves.”

“At Saltpetre, we’ve stopped one thing, disturbance through the winter, and we’re working on the other part, the physical changes,” he said. “And it’s providing more of a safe haven for the species.”

Back at Bat Cave, researchers had been piecing together some troubling evidence.

Counts in the 1980s found as many as 50,000 roosting Indiana bats, which declined to the 30,000s in the 1990s and has since fluctuated up and down.

Periodic flash floods would kill or displace thousands -- there are now some 2,100 bats in the risky environment of Laurel Cave, tucked into crevices at 200 per square foot or more to avoid the cave’s “wind tunnel” conditions.

Extreme temperature shifts inside Bat Cave itself likely claimed others. Even vandals once broke in and killed many while they slept.

“It is increasingly clear why past protection so often failed to restore populations,” Kennedy and Tuttle wrote. “In cases of failure, key hibernation roost temperatures had been altered without being restored, or caves of last resort, that may have even served as periodic death traps, had been protected simply because they still contained displaced bats.”

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At Carter Caves two weeks ago surveying bats, Kennedy explained that the research is now turning Saltpetre Cave into a model of what can be done in southeast United States’ caves to reverse the decline of the Indiana bat.

"I get kind of excited about these things because it’s a neat thing and it’s a totally different paradigm from what we’ve been used to as bat conservationists,” he said.

“We’ve been going to a cave (like Bat Cave) and saying, ‘Oh, this cave has bats, we must protect it.’ Now we’re looking at the cave and we’re saying, ‘Well, this cave isn’t real good. Bats are here, but this doesn’t seem like a typical cave, you know.’ Where is the motherlode bat cave? Where are these key sites they used historically?”

Kennedy is looking across Kentucky, Indiana and West Virginia for those caves, those in the same situation as Saltpetre — abandoned by Indiana bats because of mining or tourism. Caves that are complex, usually multi-level, cold-air traps, as he says.

Because caves mined for saltpetre generally fit that model, he and volunteer cavers started surveying them last year for roost stains and other evidence.

They’ve uncovered several in Kentucky, such as Saltpetre Pit in Pulaski County where removing a trash pile in its entrance should help bats return, the Great Saltpetre Cave Preserve in Rockcastle County, and six or seven more where undoing alterations could help.

Work’s also planned at Saltpetre Cave again this summer. BCI is seeking grant funds to enhance another entrance that could restore airflow to trap more cold air.

That might be why researchers didn’t see the “dramatic climb” in this year’s bat count. That is, more restoration of the microclimate is needed, although Kennedy’s quick to say you cannot make assumptions based on one year of data.

And in West Virginia, BCI has a list of about 80 caves, of which Kennedy hopes to visit 20 to 30 this year.

The plan is to narrow the entire list down to 100 or so historic Indiana bat caves, assess them, and prioritize them to a handful of significant ones.

“We’re finding those caves and doing the restoration-ecology thing with them, restoring them to what condition they must have had, which may be as simple as preventing winter distrubance,” Kennedy said. “We’re going from a kneejerk put-a-gate-on-it reaction to looking at the whole system ... and how to manage that.”

In other words, using Saltpetre as a model, he said, “we can recognize these caves where bats once roosted, and by working to manage for bats, they will recolonize those sites.”

Scientists have no way to tell how many caves were used by Indiana bats before humans started settling on this continent, Kennedy added.

But, what if they can find even two or three caves that once sheltered just 50,000 bats?

“That doesn’t sound like a lot, 50,000 bats, but you think about that -- two caves with 50,000 bats, for 100,000 bats. That’s a quarter of the known population we can rebuild that in just two caves, and that’d be huge for ... rebuilding the species, which is critically in peril,” he says.

“So, if we can find a cave here that once had 20,000 bats, and cave there that had 50,000 bats and a cave here that had 20,000 bats, and a cave like Saltpetre that may have had maybe 100,000 bats ... It boggles the mind how much good that could do to bring back the species.”

ALLEN BLAIR can be reached at ablair@dailyindependent.com or (606) 326-2657.