Missing Bats at Devil’s Sinkhole

Devil’s Sinkhole in Rocksprings, Texas is normally home to two million bats over the summer. The bat flight at dusk draws flocks of tourists to watch the two million bats swirl up the 130-foot (40 m) pit and fly off into the night sky to consume literally tons of pesky insects.

Usually. But not the summer of 2021.

Devil's Sinkhole National Natural Landmark, 1971
Devil's Sinkhole was established as a National Natural Landmark in 1971.
Don Kennard plaque at Devil's Sinkhole.
Former Senator Don Kennard, champion of conservation in Texas.

Bat typically arrive in the spring, but by June 2021, there were still no bats. The rangers at Devil’s Sinkhole State Natural Area became concerned. There was a devastating freeze in February that killed off many plants and animals. Entire bat colonies in San Antonio and Austin froze to death. White-nose syndrome (WNS) has wiped out about 98% of all the bats in the northeastern United States, and had recently spread to Texas. Could either of these be responsible for the missing bats at Devil’s Sinkhole? There was also a ceiling collapse at the bottom of the entrance shaft that was visible from the surface. Did their roost become damaged?

Allan Cobb always breaks the rules.
Don't try this at home. We're professionals.
Allan Cobb (left) breaking the rules with Oscar Berrones (right).

Crazy Cavers

That’s we come in—cavers, the crazy people who actually enjoy crawling into holes in the ground. We were asked to rappel into Devil’s Sinkhole and try to determine what happened to the bats. We had a great team: Joe Ranzau, Allan Cobb, Linda Palit, Oscar Berrones, Pam Campbell, and me (Bennett Lee).

I have explored a plethora of caves and pits, but this was my first time at Devil’s Sinkhole. Wow! It’s impressive. A 50-foot (15 m) wide pit descends straight down 130-foot (40 m). As you descend, there are verdant shelves covered in ferns and thick moss. Then suddenly the pit walls disappear as you emerge into the top of a huge room over 300 feet (100 m) from end to end and 200 feet (60 m) across. Photos and videos just cannot do justice to the experience of dropping through the roof of a room the size of a football field.

Even though we touched down at 130 feet (40 m) below the surface, we were actually on the top of “The Breakdown Mountain,” which is a huge breakdown pile created as the ceiling and pit gradually collapsed rock after rock over millions of years. Following the slopes of the breakdown, the cave continues down another 200 feet (60 m) deeper at the edges.

Where we stood at the top of the breakdown, a little mouse scurried around. I have no idea how he survived the fall. Having never interacted with humans, he wasn’t very intimidated by our presence and scampered about, posing for pictures. I also snapped photos of the lush vegetation in the cave. The large entrance that let in ample sunlight combined with the wet, drippy cave made it a haven for ferns and plush moss.

Meanwhile, Oscar circled the room looking for bat roosts, which are usually dark stains on the ceiling with guano on the floor. We found several large roosts. There were no dead bats from the freeze or WNS, which wasn’t a surprise because bats typically don’t hibernate in Devil’s Sinkhole. However, we discovered why the bats weren’t there.

Devil's Sinkhole map
Devil's Sinkhole map, courtesy of the Texas Speleological Survey.

First, More Photos

Before I tell you what happened to the bats, I want to share a few photos that show this spectacular cave.

I want to note even my widest shots did not capture the entire room. For those photography geeks reading, I was using a Canon R5 with a 24–105mm Canon lens. 24mm wasn’t wide enough, so immediately after this trip, I picked up a Laowa 12mm zero-distortion rectilinear lens specifically for this cave and Punkin Cave. I’m hoping to get something close to Allan Cobb’s historic photos of those huge entrance rooms with his 10mm lens.

I have some great photos of the plant life, the entrance pit, and most spectacularly, Pam and Oscar ascending the pit. 

Enough with your awesome photos...What happened to the bats??!?

Texas had an unusually wet summer. Grass that was normally brown and dying from the summer sun and drought was still a lush green. All that rain slow worked it way through the Texas limestone, and when it hit the cave, started dripping. Some of the particularly drippy locations were where the bats roost.

Thus, just like you would do if your ceiling started dripping right above your bed, the bats found somewhere else to sleep.

This was June. By July, Texas has started drying out again and some of the bats returned. Not all two million, only a few hundred thousand. But it was enough have some bats for the Devil’s Sinkhole Festival on October 1–2, 2021, celebrating 50 years as a designated National Natural Landmark. Good thing because they had over 100 people show up for the bat flight.

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