The Nature Conservancy. Protecting nature. Preserving life.™

by Paul Kingsbury

To fight white nose syndrome, an epidemic that is causing catastrophic die-offs in America’s cave bat populations, The Nature Conservancy in Tennessee is proposing a radical idea.

The plan? To build an an artificial cave next to an existing natural bat cave in Tennessee. The artificial cave can be disinfected of the tell-tale white fungus that is thought to cause white nose syndrome—thus creating a safe haven for bats.

An expert scientific panel has reviewed the plans for the structure, and the Conservancy is collaborating with Bat Conservation International to further review and refine the plans. The Nature Conservancy is currently planning to break ground for the artificial cave this spring in middle Tennessee.

Nature.org talked with Cory Holliday, cave and karst program director for The Nature Conservancy in Tennessee.

Extra: Read Cory Holliday's recent blog post about the artificial cave.

Nature.org:

Cory Holliday:

White nose syndrome has been devastating to cave-hibernating bats since it was discovered in New York state in 2006.

We’ve lost more than a million bats in 19 states, and we still haven’t identified any way to control bat mortality rates or the fungus that appears to be causing those deaths. Up to this point we have simply had no tools to employ to keep bats from dying.

Nature.org:

Cory Holliday:

In June 2010, I attended a U.S. Fish and Wildlife Service-sponsored workshop with cave and bat experts on keeping and breeding bats in captivity to protect them from white nose syndrome. The idea came out of a small working group session. And these cave experts thought it might have the potential to save large numbers of bats.

Nature.org:

Cory Holliday:

It was a bit of serendipity. On my drive home from the U.S. Fish and Wildlife Service workshop, I visited a friend in Kentucky who happens to be into alternative home building methods. He turned me on to Formworks Building, Inc. This company builds structures of various kinds out of shotcrete, which is a pressurized, textured concrete. It’s sprayed onto a steel frame. It’s the same technology that’s used to make a swimming pool, just turned upside down.

Nature.org:

Cory Holliday:

It’s a little like that Field of Dreams movie: If you build it, they will come. Past experience shows that bats are constantly seeking new habitats. They move from cave to cave, tree to tree, always looking for new places that meet their needs for roosting and hibernating.

Nature.org:

Cory Holliday:

Not for cave-hibernating bats and not to address white nose syndrome. Artificial roosts have been built that simulate hibernating roosts in trees for Rafinesque big-eared bats. In fact, we’ve built them successfully in Tennessee to replace lost habitat for the Rafinesque bats, using plans from Bat Conservation International.

And then there is a fellow in Texas who built an artificial roosting cave for Mexican free-tailed bats. It’s been a great success. When he started, folks thought he was crazy. But the bats are there in great numbers today.

Nature.org:

Cory Holliday:

It’s all in the design. What makes this structure so ideal is the Shockcrete. It’s a textured, stonelike substance much like the limestone of Tennessee caves. Our cave interior will have folds and cracks like a real cave. In fact, we’ve talked with Formworks about ways to maximize surface area and allow for cracks that will create microclimates within the artificial cave. That’s because bats do move around in the winter during hibernation season in order to find the microclimate they want.

In order for a cave like this to work it has to be a cold air trap. It has to be underground. The ceiling has to be farther below ground than any entrance to create that cold air trap. It has to have air flow through two entrances, and the entrances have to be at differing levels, because the flow of air is much like the thermodynamics of flowing water. Using a specially structured entrance door, we can adjust that air flow to fine-tune the climate.

Nature.org:

Cory Holliday:

The bats should go in as long as we get the temperature and humidity right. We believe they will. If they don’t go in, then we must have done something wrong, and we would make any adjustments we can.

But if the bats just wouldn’t go in, then we could use the cave as an on-site laboratory to study bats that we brought in. Unfortunately, the gray bats of the natural cave we plan to build next to are a federally listed endangered species, and we probably would not be allowed to move gray bats without a permit.

Or we could work on toxicity trials with anti-fungal agents and test them on cave micro-organisms that we would bring in. The thing is, we know of anti-fungal compounds that will kill the Geomyces fungus that is associated with white nose syndrome. Unfortunately, those chemicals, in the wrong concentrations, also kill many other cave life forms, including microorganisms.

So a place that mimics a natural cave environment would be a very useful laboratory for testing these anti-fungal agents on other cave-dwellers, which don’t survive so well in traditional laboratories.

Paul Kingsbury is a conservation writer for The Nature Conservancy in Tennessee.