How you became a caver
What first drew you into the caves of Central Texas?

When I enrolled in the Geography department at SWTSU (Texas State), I studied Physical and Environmental Geography with the intent on working for the NPS, Forest Service or the BLM thinking that I would like studying rivers and watersheds. The University however had a huge and historically significant Cave Club (Grotto). I met some friends that persuaded me to try it out.

I liked it immediately. It was very physical activity and was related to my field of study. Landscape interpretation was a high field of interest for me. The people were interesting. I kept up with it through graduate school, never thinking that it could lead to a career.

While in graduate school I became chairperson of the grotto. One afternoon the phone rang. A local woman had what she thought was a cave on her property sealed, she said, under a pile of rocks.

I called an experienced caver friend and we drove out to have a look. She led us to a strange mound of stones at the edge of her land and we started pulling them away. When the hole was finally wide enough to enter, my friend looked at me and nodded. I was going in first.

I slid in and found myself in a low, circular room with a couple of small side passages across from each other. There was also an animal trap near the entrance with the remains of an animal's foot still in it.

I started thinking that I may very well be the first person that has ever entered this space. I smiled to myself deeply realizing this is a frontier that I could explore since I would never be an astronaut. That was when I realized that I understood what the caving bug was. And knew that I would continue with this activity.

Was there a moment underground that changed how you see the landscape above?

It was a little opposite. When we were amateurs, we volunteered to help set up state parks like Kickapoo Caverns, among others. I learned to do karst terrain surveys which involved conducting grid searches looking for potential caves.

You learn to read the landscape. We would look to see where the ground leaks. It can be very subtle; nothing more than leaves washed into a pile. Using a crow bar or other probe would determine if this drain went further than just the surface.

Reading the landforms to detect if there is an underground aspect is something that I have always loved doing. We exposed numerous caves that few people would have detected. We would often say that "I do know my ass from a hole in the ground".

How has the region's cave ecosystem changed since you started exploring?

That's an interesting question. I never expected to see any changes over an environment that is almost as stable as that as the moon. I remember seeing porcupines in far west Texas but never in Central Texas.

When I was monitoring endangered karst invertebrate caves, I noticed an increasing frequency of porcupines. They seemed to be displacing other mammals like ringtails and raccoons. Eventually, I noticed that they are prolific poopers. They dramatically increased the amount of organic material deposited in these very sterile environments.

I found it necessary to contact the USFWS regarding the prolific increase in organic material in caves with endangered karst invertebrates. They didn't give me much to go on but I found a student in search of a PhD. She studied the porcupines including collaring them, which was very interesting in itself.

Not much came of the porcupines. I believe climate change is the culprit. They are very interesting mammals and I don't think the added organic material had any effect on the cave dependent species but it was an interesting study nonetheless.

Karst 101
How would you describe the Edwards Plateau karst system to someone who's never seen it?

Limestone landscapes are characterized as being easily (geologically speaking) eroded landscapes by water alone. The Edwards Plateau is one of these landscapes. Karst is characterized as a landscape dominated by caves, sinkholes and springs. Central Texas is dominated by these things.

Barton Springs, The San Marcos River and Comal River are all features of the Edwards Plateau. In addition, there are multiple commercial caves to visit and hundreds more that are not commercial.

Why are caves such sensitive ecological zones?

Caves are extremely isolated ecosystems, comparable only to extreme environments like the arctic or deep-sea environments. Organic input to form the basis of a food chain is very limited.

Chris Thibodaux in the Lion's Tail Room in La Gruta del Palmito, Bustamante, Nuevo Leon, Mexico, surrounded by stalactites and stalagmites
Chris in the Lion's Tail Room, La Gruta del Palmito, Bustamante, Nuevo Leon, Mexico. Photo courtesy of Chris Thibodaux.
Biodiversity underground
What species in Central Texas caves are most at risk right now?

That's difficult to say. Some bats are protected but they are more mobile and have more options than cave adapted invertebrates and salamanders that may be found in only one cave.

Can you explain the role of cave crickets and bats in sustaining subterranean ecosystems?

Bats occupy fewer caves than cave crickets, which are in almost every cave. Both serve to bring in organic nutrients from the surface because they leave the cave at night to forage. They then return and deposit guano, eggs, and themselves in the cave. This organic material forms the basis for the food web for creatures unable to survive outside of the cave environment.

What's the most surprising biological interaction you've witnessed underground?

Having entered caves on an almost daily basis from the mid 1980's up until 2020, I observed many things. Mammals are really the ones that stick out the most, even though they really aren't the focus of most trips.

I was managing many of the same caves throughout this time entering all of them on a near monthly basis. Early on, the more frequently observed mammals were raccoons. Sometimes a possum or more rarely, a ringtail would be observed.

These observations became less frequent over time. Instead, porcupines became more frequent in Central Texas. I had seen them associated with caves in far west Texas but didn't frequent those caves on a regular basis so my observations were limited by that fact.

I noticed they became more frequent in the caves I was managing and that they seemed to be displacing the other animals using the cave environment. Porcupines are prolific poopers and it's about the nastiest I have ever seen. My job was to crawl over it and search for bugs but I was more concerned about the extreme added organic input and how it would affect the invertebrate species I was supposed to be monitoring.

I discussed with the United States Fish and Wildlife service about potential options. We decided to find a PhD candidate that wanted to study porcupines in south-central Texas. We found a professor at Texas A&M that had an acceptable student.

A young lady that had previously written an interesting Master's on roadrunners was selected. She didn't have cave experience but fortunately the porcupines really didn't venture much beyond the entrance. One of the cool things we decided upon was to radio collar the porcupines. The added benefit which I was aware of is that they can be tracked in real time while underground, in addition to the memory storage.

Porcupines are nocturnal and very harmless. Their defense mechanism is simply to find a little nook and place their back spines facing outward. They can also make some of the strangest sounds I've ever heard in a cave.

Threats & pressures
What are the biggest threats facing Central Texas cave systems today?

Without a doubt, overdevelopment and over pumping of groundwater.

How does rapid development in Austin and the Hill Country affect caves and aquifers?

They are frequently sealed and/or filled. This reduces recharge for the groundwater systems, dries out what's left of habitat in the cave system and can eventually pose a hazard for any nearby development.

Chris Thibodaux standing among stalactites and stalagmites inside Bustamante cave, Nuevo Leon, Mexico
Inside Bustamante cave, Nuevo Leon, Mexico. Photo courtesy of Chris Thibodaux.
Rewilding potential
How do caves and groundwater fit into the larger idea of rewilding?

Rewilding is a relatively new term to me. There are examples of successful mitigation and restoration of habitat in cave resource management.

Chris Thibodaux crawling through a tight underground passage, wearing a muddy red jacket and helmet with headlamp
Chris navigating a tight passage underground. Photo courtesy of Chris Thibodaux.
Stories from the field
What's the most unforgettable cave you've ever explored?

That's a difficult question to answer. The first cave I was ever the first to explore was very memorable even though it was a small and typical Central Texas cave with nothing exceptional in it. I've seen parts of Carlsbad Caverns that few ever get to see including a mountain of calcite encrusting ancient bat skeletons. Many of the giant caves in Mexico are as fabulous as Carlsbad. The longest cave in Texas is a 30 plus mile long stream passage that comes out at a spring entrance. Each cave is very unique.

Have you ever witnessed a cave ecosystem recover after protection or restoration?

Many caves in urban areas have been formed into karst preserves and are essential parklands for the nearby neighborhoods. The caves are gated so access is limited. There is often mitigation and restoration (like removal of sediment washed in by construction activities). Recharge enhancement is often a part of the mitigation and restoration activities.

What's a moment underground that you wish everyone could experience?

Each cave is essentially a sensory deprivation tank. Turn off all lights and get comfortable in the dark. It's amazing the places one can get comfortable. The only sound you hear is the slow drip of the stalactites, your breathing and heartbeat. It's a very peaceful environment.

Call to action
What can everyday people do to protect caves and groundwater?

Get educated on the issues. Reduce water consumption and vote for politicians that limit development over environmentally sensitive areas.

What policies or protections would make the biggest impact right now?

Limit groundwater pumping and protect environmentally sensitive areas.

How can landowners participate in cave-friendly rewilding?

Reduce or eliminate watering. Allow native vegetation to flourish, especially for pollinators. Reduce waste and become educated.