I’m perched on the stony lip of a gaping hole in the prickly Chihuahuan desert scrublands near Del Rio, checking and rechecking the rappelling harness buckled snugly around my waist. Forty-five feet below, four fellow cavers stand atop a bus-sized mound of bat guano, blinking up at me as I lean back for the drop into the shadows of Punkin Cave.
I’m afraid of heights, and the thought of plummeting four stories into the bowels of the earth is making my hands shake. I squeeze my eyes shut for a moment, trust the cavers who are belaying me, and lower myself slowly into the abyss. For the next few minutes I dangle in midair, scuttling down the rope like a spider on a silken thread.
More than 5,600 documented caves twist and turn their way through the limestone and gypsum bedrock that comprises much of Texas’ underbelly. That’s a lot by any standard, but it’s even more impressive considering most of the state is privately owned land, where caves haven’t been investigated or mapped. Many of the known caves are clustered along the Balcones Fault Zone, a crack in the earth’s surface that curves from Waco to San Antonio and west toward Uvalde County; and along the Llano Uplift, a geologic dome of rock in the Hill Country west of Austin.
Caverns like Punkin Cave—which spreads its tentacles beneath a 225-acre property owned by the Texas Cave Management Association—provide vital habitat for the likes of bats, salamanders, flatworms, fish, insects, and even microbes that could one day provide the source of new antibiotics. Their delicate passageways serve as an underground plumbing system, funneling water that bubbles forth in springs and feeds city utility systems. Caves also provide clues about the health of the environment above ground.
And although they’re easy to overlook, caves face the same risks posed to the rest of the environment as Texas grapples with rapidly growing urban and industrial development. Tainted runoff and infill are two of the primary dangers to caves, according to the Texas Cave Management Association. That’s why the San Antonio-based nonprofit works to preserve caves and shed light on their sometimes-hidden role in the natural order.
“In my eyes, caves are no different than creeks or wetlands or anything involved with the natural process going on around us,” says Jim Kennedy, an officer in the Texas Speleological Society who’s leading our exploration of Punkin Cave. “The species in caves are like canaries in a coal mine. They’re environmental indicators, and they’re highly specialized. If they start dying and disappearing, that tells us something bad is happening, like pollutants or runoff.”
After landing on the guano pile in Punkin Cave, I pull a buff over my nose to block the guano dust and dull its acrid aroma. Kennedy then leads our group of five into a tunnel, where we crawl on hands and knees down a narrow passage with our headlamps shining ahead. At the front of the group, Kennedy hollers out a warning: “We’ve got bats!”
With a rustle and a whir of flapping wings, hundreds of the flying mammals suddenly swoop past and bounce off me. When one finds its way up my left pant leg, I push the furry, fig-sized creature out, and silently thank Kennedy for loaning me a pair of knee pads, which are strapped tightly around my calves. Cave creatures don’t often win popularity contests, Kennedy notes. Most are pale because they don’t need pigment to protect them from sunlight. Many are blind and have long appendages to feel and sense vibrations. But that doesn’t diminish the significance of creatures like salamanders and cave crickets. They’re part of an intricate ecosystem.