Like the first drop of rain that brings on a storm, a single Mexican free-tailed bat emerges around dusk in summer from the mouth of Bracken Bat Cave, a 100-foot-wide crescent-shaped opening into a cavern in the Hill Country north of San Antonio. The bats’ exodus is slow at first as they linger at the cave’s lip, circling round and round inside before emerging.
As more bats flow from deep inside the Earth, the fluttering of wings grows louder, like a rainstorm gathering. Over the next four hours, tens of millions more bats will follow the first in streams of graceful swirls that rise into the wide sky and dissipate in the distance.
Surrounded by 697 undeveloped acres owned and protected by Austin-based Bat Conservation International, Bracken Bat Cave is the summer home to the largest colony of bats in the world. Each year, the mostly female, dark brown to gray Mexican free-tailed bats migrate from Mexico to Texas for summer to birth and raise their pups. While no congregation is as large as the Bracken Bat Cave colony, these bats take refuge all across the state, including in downtown Austin under the Ann W. Richards Congress Avenue Bridge, which shelters the world’s largest urban bat colony.
Every night from about March to October, these tiny creatures fly out from their underground roosts to feed. They spread out over a 60-mile radius from the cave at heights of up to 10,000 feet over the next eight to 12 hours to feed on hundreds of tons of insects, such as moths and agricultural pests. Their emergence is so dense that it shows up on Doppler radar.
The nightly bat emergence from Bracken Bat Cave lures a host of expectant watchers. A Great Horned Owl and two Harris’s Hawks scope out potential dinners from nearby trees. Their shapes cast ominous silhouettes against the pink and blue horizon at sunset. On the ground, skunks, raccoons and opossums prowl, and rattlesnakes lurk in wait to strike low-flying bats from the air.
People, too, can witness the bat flights from Bracken Bat Cave (for more information, go to batcon.org). This summer, for the first time in BCI’s 20-year ownership of the cave, bat flights are open to the public for a fee on Wednesday through Sunday evenings through late October. Additionally, purchasing memberships to BCI provides visitation options, including free tickets or discounts on tickets, depending on the membership level. Memberships start at $30.
In August, the meet-up time is 5 p.m., and bats emerge around sunset. After gathering at Natural Bridge Caverns about two miles away, groups of visitors caravan over rugged dirt roads and then hike about half a mile on easy-to-walk trails to a natural amphitheater-style seating area overlooking the cave. Near the site, signs encourage visitors to be quiet so as not to disturb the bats and enjoy the primitive, natural experience. The excited chatter dies down as spectators settle on cedar benches and boulders on the rim of the sinkhole above the cave.
But once the bats take wing and begin swirling directly overhead, guests don’t need to be shushed. Together, they fall silent in reverence, like desert dwellers watching and listening to the pitter-patter of welcome rain.
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Suzanne Haberman, staff writer
