Going batty at Eckert James River Bat Cave Preserve

July 01, 2017
Visitors await the emergence of Mexican free-tailed bats from the Eckert James River Bat Cave Preserve near Mason. Pam LeBlanc/American-Statesman

Just before sunset, a few bats flutter and chirp near the mouth of a cave southwest of Mason.

A great horned owl flaps into a nearby treetop, and two snakes — nicknamed Sir Hiss and Miss Hiss by the locals — watch from a nearby crevice, part of an audience of predators waiting for an easy meal.

Here at Eckert James River Bat Cave Preserve, the nightly summertime emergence of Mexican free-tailed bats from a 65-foot hole in the ground unfolds up-close and furious.

Sit on a bench in the front row of the viewing area and you’ll feel the breeze created by millions of swirling creatures. You’ll hear the flapping of wings the size of cocktail umbrellas. You’ll smell the guano, too.

“It’s like a big hamster cage,” someone whispers in quiet awe as a whirling vortex of mammals rises from the mouth of cave, tracing a ribbon into the darkening night.

Researchers estimate that some 1.6 million female bats come here every May to birth and raise their pups. The population swells to 10 million or more when the babies are born and more adults arrive later in the summer, says bat cave steward Vicki Ritter, who is providing live analysis of the tornado of bats streaming from the cave, which is located on a small preserve about two hours from Austin that’s owned and managed by the Nature Conservancy in Texas.

By comparison, about 1.5 million bats live under the Congress Avenue Bridge in Austin, and some 20 million live at Bracken Bat Cave near San Antonio, the largest known bat colony in the world.

“They’ll boot scoot across, trying to fly into the strongest air,” Ritter says as the bats rise into the sky and catch the wind.

Ritter snags one in a net and holds it in her hand so spectators can take a close look. Despite the bad rap they get, the bats are surprisingly cute: pug nose, wrinkled lips, big, expressive ears.

“They’re not trying to suck your blood. They’re insectivores,” Ritter says.

The pint-size creatures pack a punch, too. They weigh about 15 grams each — roughly the equivalent of two nickels — and eat nearly their body weight in insects, including mosquitoes and crop-damaging moths, each night. They use their stubby tails as baseball bats to club bite-size bugs and fling them into the sweet spot in their wing.

“It’s a home run every time,” Ritter says. “They really are Babe Ruths.”

Bats also disperse seeds and help cross-pollinate plants. They can travel long distances, too, and fly at speeds between 15 and 30 miles per hour, or double that with a tail wind. Bats tagged here at Eckert James River Bat Cave Preserve have been spotted 100 miles away in San Angelo.

When they’re not out snacking on pesky insects, they hang by their feet from the ceiling of the cave — unless they’re pregnant. Before they give birth, the females cling to cave walls with their thumbs. Each square foot of cave ceiling can hold 500 jelly-bean-size babies, which are weaned in about four weeks, Ritter says.

The bats typically depart with the first cold front of the season, heading back to Mexico sometime in October. Mexican free-tailed bats can live up to 30 years, but pesticides shorten their life spans.

The cave has long been open to visitors curious about bats.

W. Phillip Eckert acquired the property in 1907. He mined guano and sold it to nearby farmers for fertilizer. His son Lee continued to protect the cave and allowed visitors to watch the bats. He left it to his family when he died in 1967. His children, Richard Phillip Eckert and Virginia Eckert Garrett, donated the cave to the Nature Conservancy in 1990.

Today, visitors can drop by to watch the show Thursday through Sunday evenings during the summer. A $5 donation per person (ages 5 and under free) is requested.

“We’ve been coming (to the Llano River) for four years and never came out for this,” says Matt Maroney, 40, of San Antonio. He and his family are staying in a nearby cabin, and they’re making their first trip to the property to see the bats. “We can’t believe it, because this is really neat. Gosh, what an amazing experience — this is better than a Broadway show.”