Member's Night at Bracken Bat Cave

Editor’s Note: The following story is part of a periodic series exploring regional issues of interest or importance outside San Antonio.

Like me, you might think you can picture 10, 15, or 20 million bats emerging from a cave before you actually see it – and maybe you can. But seeing it in person is just … better.

And in light of the proposed 3,800-unit Crescent Hills housing development that aims to plant its roots a little more than a mile from the Bracken Cave, it’s a good time to go see what all the fuss is about. It’s bats, for sure, but it’s more.

Last night was Member’s Night at Bracken Cave. About 60 people, Bat Conservation International (BCI) members and their guests, watched 15 – 20 million Mexican free-tailed bats emerge from the cave at 15 – 20 miles per hour for their nightly insect hunt. These bats call the cave home from March through October, join millions of their brothers and sisters on a migration path to Mexico, and make up the largest bat colony on Earth. The maternity colony consists solely of moms and their new-born pups.

Bats emerge from the Bracken Cave for an insect dinner. Photo by Iris Dimmik. — Bats emerge from the Bracken Cave for an insect dinner. Photo by Iris Dimmick.

The cave is a mere 45-minute drive from downtown San Antonio (well, an hour and 15 minutes during rush-hour traffic) and worthwhile for city-dwellers who want to connect with these tiny cave-dwellers. Their bodies are about as big as your thumb with a wing span of four inches.

This trip reminded me of that telephoto lens and spare time I’ve been craving to hone my photography skills. At any rate, pictures and video truly do not do the bats’ emergence vortex justice.

The first batch of Mexican free-tailed bats emerge from the cave's 100-foot wide mouth during the bats' nightly venture out to feed. Photo by Iris Dimmick. — The first batch of Mexican free-tailed bats emerge from the cave’s 100-foot wide mouth for the bats’ nightly feeding pilgrimage. Photo by Iris Dimmick.

Their chirps and squeaks as they gather just beyond the threshold of the cave’s 100-foot wide mouth sounds like the insect throng of a 100-acre forest. The bat vortex, a coordinated spiral of millions of bats, begins deep within the cave, a collapsed portion of a prehistoric underground river carved into limestone that slopes 650 feet back into the Earth.

“We’re not sure what the cue is … which bat says ‘go,’” said BCI Bracken Cave Coordinator Fran Hutchins to the crowd. “They just go.”

Anticipation levels rise when bats begin to poke through the shadows into the sunlight. Photo by Iris Dimmick.

The tour begins at the gate just off of Natural Bridge Caverns Road, on the northeast “suburban fringe” of San Antonio and about 10 miles from Loop 1604. It’s an unassuming entrance with a small BCI event sign the only signal of the scheduled public and private events. BCI owns and maintains the cave and surrounding 697 acres in Comal County.

This land is also home to nine pairs of Golden-cheeked warblers – an endangered species – lies on the Edwards Aquifer Recharge Zone, and is an outdoor classroom for nearby universities, scout groups, and plant and wildlife organizations, said BCI Volunteer and Texas Master Naturalist Coco Brennan from Canyon Lake.

Coco Brennan, BCI volunteer, and Fran Hutchins, BCI Bracken Cave coordinator pose for a photo after the tour. Photo by Iris Dimmick.

“Boy Scouts, Girl Scouts, the Native Plant Society, birding groups, all kinds of different interests (are hosted) here,” Brennan said. “It’s not just about the bats – but they are really cool.”

Upon arrival, visitors are given a liability waiver and quick multiple-choice quiz to fill out while they wait, parked just beyond the gate, for everyone to arrive. The quiz attempts to gauge visitor’s knowledge of bats and to inspire questions during the upcoming question-and-answer session at the mouth of the cave.

The caravan of visitors approach the parking area at the cave. Photo by Iris Dimmick.

“Approximately how many species of bats have been identified in the world?”

“How are bats considered in Chinese culture?”

“How much money do bats save us each year in the U.S., due to reduced crop loss and pesticide use?”

I had to answer “I don’t know” to many of the 12 questions, but most were later answered by Hutchins before, between, and after the two, five-million-plus bat waves emerged from the cave.

For mysterious reasons, the bats split up into two large groups – one departing around 7 p.m. and another at 8 p.m. – followed by a trickling of smaller groups.

Fran Hutchins holds a pound of cotton boll worm moths, the equivalent of what the Mexican free-tailed bats can eat in one evening. The colony eats approximatley 100 tons of insects per night. Photo by Iris Dimmick. — Fran Hutchins holds a pound of cotton boll worm moths, the equivalent of what one adult Mexican free-tailed bat can eat in one evening. The colony eats approximately 100 tons of insects per night. Photo by Iris Dimmick.

There are about 1,250 different species of bats. Bats are considered lucky in Chinese culture. In our region, bats save farmers about $700,000 a year on pest control and crop damage – and recent studies estimate a range of $3 to $53 billion saved in the agricultural industry nationally.

While the presentation was set up like a typical nature talk, Hutchins didn’t give a dry lecture or read from a prepared speech. Rather, he was able to speak and answer questions with authority and humor – which comes easy to folks like him that are passionate and knowledgable about what they do. He’s been at Bracken since 2006, so he’s led more than a few tours.

“Do you ever go into the cave?” an audience member asked.

“Well, let me tell you, it’s not a vacation,” Hutchins said, chuckling and grimacing while he described the 30-60 inch deep guano (bat feces), flesh-eating beetles that scavenge the cave floor, and high levels of ammonia and C02 that requires researchers to wear full-body suits in the 100-degree cave. The odor coming from the cave is strong, but not uncomfortably overwhelming.

BCI members and their guests silently watch the largest bat colony on Earth emerge from the Bracken Cave. Photo by Iris Dimmick.

While the bats circle and swarm, visitors need to be as quiet as possible. Public and member nights at the cave are limited to a max of 60 visitors. “They’re always fully booked,” Hutchins said.

Barely a murmur was heard during each emergence, approximately 10-15 minutes long each. During Hutchins’ lecture, I noted almost every single person – with the exception of a few restless younger kids – was genuinely listening to what he had to say. It was a refreshing break from texts and Twitter. His talk on the threats to bat populations received even more rapt engagement.

“Loss of habitat due to development is probably the number one threat,” he said. “As well as white-nose syndrome (caused by a fungus) … (and) wind turbines.”

The bats' flight can be seen by radar and weather satellites as the bats spiral out for their nightly insect hunt. Area map courtesy of BCI. — The bats’ flight can be seen by radar and weather satellites as the bats spiral out for their nightly insect feast. Area map courtesy of BCI.

Hutchins explained that BCI is one of the leading research groups on the cold-weather fungus that causes white-nose syndrome and on how to lower bat fatalities around wind turbines. It’s not the blade itself, but the air pressure and currents they get caught into from the blade’s wake that kills them. Helpful technologic advancements are being developed that are as complex as sending out a radar signal to keep bats away from wind farms and as simple as being able to turn off the turbines when energy generation is at its lowest and bat migration is at its highest – a feature that is surprisingly not included in most turbines.

BCI has also been in touch with Galo Properties, the Crescent Hills land owner and developer, to try to work out a possible public-private purchase of the nearby land.

Roxanna Dean, who works at the Canyon Lake Library, attended the San Antonio City Council public comment session on the Crescent Hill development in May. She bought a membership immediately afterward, she said, and last night was her first time to Bracken Cave.

Roxanna and Chris Dean pose for a photo next to three examples of makeshift bat houses at Bracken Cave. Photo by Iris Dimmick.

“When you’re sitting there (watching the bats emerge) it shows you that everything is connected,” Roxanna said and added that she’s grateful to have BCI and so many non-profits work in favor of natural resources. “I love to support them because they’re the ones that maintain these great spaces for us.”

Chris Dean, Roxanna’s grandson visiting from Illinois, came along on the tour as well.

“I don’t even like bats that much,” Chris said. “But it’s a once-in-a-lifetime opportunity … how can you pass that up?”

Moon and bats. Classic. Photo by Iris Dimmick.

Tour Information

Unfortunately, public tours for this season with BCI have been filled months in advance, so register here early next year. Member tours are a similar story, but there’s still a few spots left for the Sept. 19 emergence if you’re interested in becoming (or befriending) a member.

It’s a very short walk from parking, but you’ll want to wear closed-toed shoes and pants as it is unpaved and those bugs (read: bat food) can bite. Bug repellant is recommended. Both batches of bats emerge before sundown, so sunscreen, sunglasses, and water may be smart additions to your gear. Some visitors bring foldable chairs, though there is also plentiful bench and rock seating available on site.

For more information, visit www.batcon.org.

Want more bats? Check out “Bat Loco” on the Museum Reach

Every Tuesday night starting in July through early August, the Paseo del Rio Association, the Texas Parks and Wildlife Department, BCI, and the San Antonio River Authority host “Bat Loco,” an educational adventure near the intersection of Camden and Newell Streets (river level). At 6:30 and 7 p.m., guided “Bat Walks” starting at the Travis Street River Walk entrance and a series of informative lectures will be given at 7:30 p.m. – just before a bachelor bat colony emerges from under the I-35 bridge at dusk for their nightly hunt. Cheesy Jane’s Food Truck will be on hand each night. Free and open to the public, this event is “an attempt to raise awareness and importance on these creatures in our ecosystem.” Lawn chairs and blankets recommended.

The weekly series will come to a close with the Bat Loco Festival on Aug. 13 at 5 p.m., also free with additional booths, children’s activities, food trucks, live music and more.

Iris Dimmick is managing editor of the Rivard Report. Follow her on Twitter @viviris or contact her at iris@rivardreport.com.

Member’s Night at Bracken Bat Cave

Tour Information

Want more bats? Check out “Bat Loco” on the Museum Reach

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Iris Dimmick