Thousands of bats fly across the evening sky. — The Bats of Bracken Cave More than 15 million Mexican free-tailed bats inhabit the cave. © Karine Aigner

Bracken Bat Cave

A 1,521-acre property near San Antonio helps protect the world's largest bat colony, local water supplies and habitat for endangered species.

Going to Bat for Mexican Free-tailed Bats

Going to Bat for Mexican Free-tailed Bats (6:04) Together with Bat Conservation International and the City of San Antonio, TNC purchased 1,521 acres adjacent to Bracken Bat Cave, protecting the largest bat colony in the world, preserving habitat for endangered species and safeguarding water for San Antonians.

Protecting Bracken Bat Cave

Located roughly 30 miles northeast of San Antonio lies Bracken Bat Cave—the world’s largest bat colony. Each year, millions of Mexican free-tailed bats can be found roosting here between March and October. But this centuries-old wildlife habitat was once at risk of being developed.

Together with Bat Conservation International and the City of San Antonio, TNC secured a 1,521-acre property in Comal County, resulting in a trifecta of conservation successes for Central Texas—including protecting the home of some of the region’s most important pollinators and pest-eaters.

A sign reading bats only beyond this point sits in front of a dark, rocky cave entrance covered in shrubs and cacti. — **INSIDE THE CAVE** The floor of Bracken Cave consists of 10,000 years of guano deposits, reaching depths of 60 feet in some places. © Claire Everett/TNC

A small brown bat hands from the trunk of a tree. — **PROTECTING HABITAT** Adult bats will travel up to 60 miles away—and back—during the night, requiring significant acreage to find food. © Claire Everett

The purchase also created new habitat for the federally endangered golden-cheeked warbler and expanded TNC's work in safeguarding Texas’ most valuable resource: clean, fresh water. This acreage is located entirely within the Edwards Aquifer Recharge Zone, the most sensitive portion of the aquifer system. As one of the most prolific artesian aquifers in the world, the Edwards Aquifer provides drinking water for roughly two million central Texans, including the entire city of San Antonio. In total, TNC has helped preserve over 95,000 acres of land above or contributing to the Edwards Aquifer.

A bird with a yellow head and black and white feathers sits on a thin branch. — **SAFEGUARDING SPECIES** The golden-cheeked warbler is federally listed as endangered. These songbirds only nest in the Ashe-juniper and oak woodlands of Central Texas. © Rich Kostecke

Conservation Takes Flight

The history of this property is unique—it was previously slated to become a 3,500-home subdivision. Scientists, conservationists and community members strongly opposed the development due to the property’s proximity to the bat cave and the risks to local water supplies and established warbler habitat. After more than a year of work, this highly complex conservation deal came together with input from a broad spectrum of trusted partners. Much of the funding for the acquisition came from a coalition of public and private organizations that includes The Nature Conservancy, the City of San Antonio, Bat Conservation International, the Edwards Aquifer Authority, Forestar, the United States Army and Bexar County.

Hundreds of brown bats roost upside down, packed into a rocky cave. — **PACKED WITH PUPS** Baby bats, called pups, can be packed in as tightly as 500 pups per square foot on the cave ceiling. At five to six weeks old, Mexican free-tailed bat pups are ready to fly. © Karine Aigner

Thousands of bats fly around dense vegetation as the sun sets. — **NIGHTLY FLIGHT** The bats form their own “batnado," a tornado of bats, allowing them to gain momentum and altitude to rise above the cave entrance and tree line as they emerge. © Jacquie Ferrato/TNC

The property now creates an important link between TNC's Frank Klein Cibolo Bluffs Preserve and Bracken Bat Cave, offering the bats ample room for their nightly flightpath to feast on insects. Ultimately, through land acquisitions and conservation easements, TNC and partners have helped protect over 5,000 acres of some of the most ecologically important land in the Hill Country along Cibolo Creek. Our collective work in the area with partners is an excellent example of at-scale conservation in Central Texas.

Bat Facts

Bracken Cave

15M+

Bracken is a maternity colony; the bats that arrive in spring are already pregnant. Once their pups are born, the population of the cave doubles to over 15 million.
140tons

A single Mexican free-tailed bat will eat its weight in bugs each night. Once pups are fully grown, the bats of Bracken Cave eat over 140 tons of insects every evening.
4.5hrs

The bats’ nightly emergence from Bracken can take up to 4.5 hours and is so dense it can be seen on Doppler radar.
102°+

The temperature inside Bracken Cave consistently stays between 102-104 degrees Fahrenheit, keeping pups warm and healthy.