Log in

No account? Create an account

per amica silentia lunae

or, across the ferny brae with the evil voodoo celt

Previous Entry Share Next Entry
lone star bats, pt. 3

The reason we'd deliberately gone to south-central Texas in the summertime was, of course, bat-related. BCI has recently bought the land around Bracken Cave with the help of the NRDC. It's not open to the public yet, but they have BCI Members' Nights, and the best time to go is in the summer, so there we were.

There were more than 50 people there- BCI members, staff, and volunteers, families and children. Andy Moore of BCI was the organizer, but the site is mostly maintained by the wonderful folks of the Bexar Grotto chapter of the NSS. Bob Cowell was their main representative there, and he and Andy provided plenty of energetic and informative commentary.

We drove through an almost-desert landscape of cactus, "juniper", and other scrub for a while, and parked near an old barn. Nearby was a Civil War-Era mineshaft leading into the back of the cave (the Confederates used the guano as a source of saltpeter for gunpowder). If you approached the shaft, you ran into a hot wave of umm, fragrant air, and could hear the chittering of the bats. There are so many in the cave that they heat it to constant 104 degrees Fahrenheit, and the amount of ammonia in the air means they have to have special adaptions in order to breathe in there. Incidentally, this also drastically reduces the number of predators who can safely venture in...

From there, we trooped up to the main observation site near the cave entrance- the opening itself is at the bottom of a sinkhole. Andy and Bob started into a lively and informative lecture, while Andy's kid went around handing out those little plastic bat rings to all the kids (nice gesture). But their talk was interrupted.

With a faint rush of wings, the first line of bats began to emerge from the sinkhole- hundreds and hundreds of them. There was oohing and ahhing, but our guides shrugged and said "just wait". Most of us got up and started around the trails above the cave, getting many different good vantage points. At one place, the rising bats were backlit by the setting sun, and you could see the light shining through their wings. It was indescribably beautiful. Far away and far above, we could see bats flying off, or returning from early foraging. Mexican Free-tails fly very high indeed.

After a while, they subsided, and Andy and Bob went back to their talk while thousands more bats flew around just inside the cave mouth, for all the world like they were building up pressure for another eruption. Bob showed us Doppler radar plots of the area during a typical summer evening. First plot showed a lot of so-called "ground clutter" that was actually huge swarms of migratory crop pests. The next plot held a red blob that looked like a thunderstorm- the bat emergence from nearby Frio Cave. The next several plots showed more and more of the red blots- Congress Avenue, Bracken, etc. The second to last plot showed the bat "storms" rapidly converging on the insect "clutter". Forty-five minutes later, he told us, there was nothing. The bats had attacked and dispersed the insects.

Andy told us that each nursing Mexican Free-tailed bat has to eat it's weight in bugs every night. The Bracken Cave colony alone eats 200 tons of them per night. The insect crop pests migrate as far north as Calgary, Canada; Texas A&M scientists estimate that bat colonies along the route prevent about a billion dollars of damage by eating the bugs.

Bob also mentioned a jet that some of us had seen veer off abruptly during the first emergence- the local airports keep close watch on the bats, and the U.S. military has designated the areas around the caves as no-fly zones during the season. This plane had been a fighter, but not a military one- "There are lots of privately-owned fighter jets in Texas," he told us solemnly. "It's a hobby."

A few early-returning bats dove back into the cave in daredevil spirals, then it was time for the next phase of the emergence. Out they poured, the massed wings making a rush of noise, forming a widdershins climbing gyre that shimmered in the low sunlight, before heading out and away southeast. We were sitting close enough to the edge that many flew over our heads on their way out. There were so many of them that they made their own wind, a breeze that was strong enough to ruffle our hair and shake the leaves of nearby trees.

There are enough bats in the colony that there are twenty or thirty albinos, and we saw about five of them, as well as many with less-dramatic color phase differences. It's hard to grasp the idea of twenty thousand living creatures, much less twenty million… something in the mind gives way, and the heart drinks in what the eyes see, and words fail. Tears blurred my vision and a huge smile covered my face. I looked over at monsteralice, and we cherished the wonder in each other's eyes. For a split second only, before we looked up again.

As if by some merciful plan, the bats fell back to their in-cave holding pattern once more, and there was space again for conversation, including a bit of humor: Bob and Andy told us that when the bats return in the predawn hours, they do so in enough numbers to form a pressure wave like an avalanche. This drives hot, fetid air out of the mineshaft, to the great distress of anyone nearby… and that's where they camp when they have overnight visits there.

It was getting dark when it began again- the whirling vortex filling the cup of the sinkhole and spilling over, up and out into a churning, serpentine stream of small hungry bodies, winging towards their nightly hunting grounds. A crescent moon hung above the cave mouth, silhouetting the bats as they came forth. More and more of them, no sign of stopping this time, the millions were coming forth until the cave was empty of fliers. There wasn't much left to see as we walked back to the cars, but we could still hear the windrush of their wings.

Here are some pictures, which can only begin to convey what we saw. That night, that place, has left its mark our spirits, as sure as Newgrange or Aquae Sulis did. It will live in us for the rest of our lives.

  • 1
The pictures look increadible...

  • 1