I am a little batty which doesn’t surprise the people I love and/or annoy. But I am batty about bats. A few years ago, GE and Jonathan took Jack and me to a downtown hotel restaurant to watch the bats fly out from Congress Avenue Bridge in Austin. What a sight! One of these days, I’m going to build and plant a bat house in my backyard. I know the rabies lore and don’t plan on making a bat my pet, but it would be pretty cool to let them feed on my backyard mosquitos.
When we were in the Hill Country, we saw a Texas Parks and Wildlife brochure for the Devil’s Sinkhole just outside of Rocksprings and visited it. The Devil’s Sinkhole is a collapsed underground cavern in the Edwards Plateau near Rocksprings, Texas. According to signage at the site, water mixed with carbon dioxide sometime between 10,000 and 1,000,000 B.C.E. when the world climate was cooler and wetter. The resulting acidic solution dissolved the soft limestone rock and made a cavern. Later, when the climate got drier, water retreated, leaving a big underground cave and several thousand years ago the ground subsided and left a huge sinkhole.
The cavern is larger than a football field, about 450 feet by 250 feet, but the opening at the top is only 46 feet across. From the edge of the opening to the depth of the cavern is about 350 feet. The material from the collapsed dome formed a mountain in the center of the cavern over 200 feet high. There are underground lakes in the cavern where little shrimpy creatures, unique to the Devil’s Sinkhole, live in the darkness
Since 1985 the property has been a State Natural Area. The only way to get to the sinkhole is with public tours which the Devils Sinkhole Society in conjunction with Parks and Wildlife provides. The society offers nightly bat tours from May through September and birding tours and hikes upon demand. Their office is at the corner of Sweeten and Main in downtown; that’s the reconnoitering point for the tour. You can also watch a DVD about the sinkhole and buy souvenirs there.
The traditional story about the Sinkhole’s discovery is that Ammon Billings, the rancher who owned the property, came across the huge hole in 1876. He burst into his home, telling his wife that, “I just came from the outlet to Hell, the Devil’s own sinkhole.”
Locals explored the cavern, getting lowered with ropes. Ranchers tried to get water out of the cavern and the military used bat guano for ammunition. Frank Gray, a local cowboy, told about rolling a big rock into the hole. The cloud of bats that emerged was so thick the boys could hardly see through them.
That’s not a surprise considering that there are times when 3,000,000 Mexican free-tail bats live in the caverns. The bat population varies depending on the time of year. The highest population is in the fall before they make a collective migration to Mexico. The sinkhole bats live in two independent non-maternity colonies. Pregnant bats live separately to deliver, nurse, and partially raise their young before bringing them to a colony like Devil’s Sinkhole. The Congress Avenue Bridge, where we saw the bats emerge a few years ago, is a maternity colony and many of the sinkhole bats were born there.
The bats make the circuitous ascent out of the cavern every night at dusk. They head south every night to Uvalde, about 70 miles away as the bat flies, eating tons of insects in the wheat and grain fields. Ben, the tour guide, told a story about one night when he had set up the bat flight. He explained that the bats always emerge and fly south, and then watched as the bats headed northeast toward San Antonio. The bats confounded him and embarrassed him in front of his audience. When he watched the 10 p.m. weather and saw that a freak wave of thunderstorms had settled over the Uvalde area, he understood the bat change of plans. He still isn’t sure how they had such meteorological insight. However they do it, bats are well aware of weather changes. Insects fly ahead of a storm so when a hurricane heads to the Texas coast, the San Antonio bat colonies fly far south and the Sinkhole colonies cover the San Antonio colonies’ territory.
Contrary to most animal intelligence rankings, Ben believes that bats are just below humans and possibly ahead of dolphins. A dentist in the 1940’s must have agreed because shortly after he visited the bats at Carlsbad Caverns he devised a plan to strap napalm on the bats and set Tokyo on fire. Sounds batty to you? Our government spent $2 million dollars checking out the plan dubbed “Project X-Ray.” Scientists equipped forty Mexican free tail bats with tiny parachutes and teeny napalm bombs and loaded them into a tray. They then packed hundreds of these trays into a ventilated bomb case. The idea was that the bats would wake and fly into the attics of Japanese buildings where the timer on the bomb would go off and burn down the structures.
On the test flight, most of the bats did not wake up on command; the ground was strewn with little bat bodies. The parachutes were too small and the bombs too big. The bats that did wake up perched in an Air Force control tower, barracks, and hangar, set them on fire, and burned them to the ground.
Bats 1; Project X-Ray, 000.