Bracken Cave Preserve has more than bats. BCI staff and volunteers steward all types of wildlife.


By Paul Hormick

Bracken Cave Preserve Trail Map. Photo by Rachel Harper

The centerpiece of Bat Conservation International’s Bracken Cave Preserve is, of course, the cave and the millions of bats that live there. But BCI is also involved in the stewardship of the preserve’s 1,500 acres of hills, canyons, woodlands, and grasslands north of San Antonio, Texas (An adjacent 2,500 acres are preserved by the Nature Conservancy). On a recent Bat Chat webinar, Fran Hutchins, Director of Bracken Cave Preserve, and Krystie Miner Project Coordinator for the preserve, detailed the other conservation efforts on the protected lands.

Bumblebee on flower at Bracken Cave Preserve. Photo by Rachel Harper.


BCI performs regular bioblitzes. Volunteers and staff walk around the preserve and record every living thing they see using a phone app, iNaturalist. When someone takes a photo, the app identifies the species in the picture and records the location as well. “Plants, animals, fungi, any living organism will be counted,” says Miner. Each photo contributes to the iNaturalist database, which is then used by BCI as an ongoing census of the biodiversity on the preserve.


Live Oak Tree on Bracken Cave Preserve. Photo by Rachel Harper.

Old growth trees are inventoried during legacy tree surveys. “We are looking for trees of a certain size,” Miner says. Each species of tree, which are mainly live oak, cedar elm, and Ashe juniper, has a circumference that qualifies it as a legacy tree. Once a tree is identified as old growth, the survey team tags it and takes a number of measurements that they record on a phone app, Survey 123. BCI then uses the database to track the status of the trees over time. The oldest tree, a live oak, has been found to be over 300 years old.


The preserve is critical for the golden-cheeked warbler as they breed and raise their young solely within Edwards Plateau ecoregion of central Texas after wintering in Central America and migrating north. The birds like to use the loose bark of Ashe juniper trees to build their nests. They also feed on insects that are attracted to the Ashe juniper and cedar elms. Listed as Federally Endangered since 1991, this striking bird of black and gold needs large areas of habitat to thrive, which makes it vulnerable to increasing urban development. Other threats include habitat loss and warming temperatures. Bracken Preserve is an official Important Bird Area for this species. Following protocols established for these areas, BCI surveys for the warbler. Hutchins says, “Our warbler population is very stable. We have 22 nesting pairs on our 1,500 acres.”

Working with Dr. Troy Murphy, a biology professor at San Antonio’s Trinity University, BCI conducts research on the black-crested titmouse, a small songbird that lives in southern Oklahoma, a few places throughout Texas, and northeastern Mexico. The birds nest in cavities but will also make their nests in man-made nest boxes. The university has put up some 98 of these boxes on the preserve and installed a number more on the neighboring preserve that is overseen by the Nature Conservancy. The nest boxes are monitored through spring, the titmouse’s breeding season. “We record if a nest is present, if there are eggs, how many eggs, how many nestlings, and the stage of development,” Miner says. Researchers also band the nestlings when they are old enough, enabling the tracking of the birds’ movements and their behavior after they have grown and left their nest boxes. The research team also collects blood samples from the birds to get genetic information. Much is unknown about this bird species, and the researchers are still discovering a great deal about their fledgling behavior, social group composition, and communication signals.



Bracken Preserve serves as the recharge zone for the Edwards Aquifer, which provides water to over 2.5 million people. As part of their groundwater management, BCI regularly thins Ashe juniper and other trees, using the thinned brush to create dams to control erosion and check the runoff into the creeks of the preserve.

Bracken Cave Preserve volunteers. Photo by Krystie Miner.

Fire has naturally occurred in Texas Hill country for millennia, and BCI replicates this aspect of the ecosystem for the grasslands that are interspersed among juniper oak woodlands. “Fire is a very important tool,” says Hutchins. “We’ll burn a few hundred acres every three to five years, depending on the weather and drought conditions.” BCI conducted burns on the preserve in 2019.

Hutchins emphasizes the importance BCI’s volunteers have in the guardianship of the preserve. “We have over 100 volunteers on our roster,” he says. “They help with everything from Ashe juniper clearing to trail work to water quality monitoring of some of the ponds we have on the preserve. They help lead our bat flight tours; do our education programs; they also help with the bioblitzes. Our biggest resource that we have is our volunteers.”


Fran Hutchins

Director, Bracken Cave Preserve

Fran Hutchins – Director, Bracken Cave Preserve

Fran has been with Bat Conservation International since 2006, directing educational bat flight programs and the restoration work on BCI’s Bracken Cave Preserve and working with Central Texas landowners protecting other bat roosts. His work at the preserve protects the largest colony of bats in the world.

He is often asked to speak at various events, sharing his passion for informing the public about bats. This extended’s to schools, zoos, Scouts and organizations from around the world. He has been featured on Texas Country Reporter, Travel Channel, several documentaries as well as Texas Highway Magazine.

In 2013 he was recognized by the US Forest Service for Wings Across the Americas / BatsLIVE education program.

Fran is also a Caver and Texas Master Naturalist and Eagle Scout.

Krystie Miner

Project Coordinator

Krystie Miner – Project Coordinator

Krystie began working with BCI in January 2023 as the Project Coordinator for Bracken Cave Preserve. She coordinates volunteers to lead tours of Bracken Cave and to help with numerous other research, conservation, education, and citizen science projects. She also aids in other BCI projects as needed, including White-Nose Syndrome surveys and swabbing agave plants for eDNA.  

Krystie has a background in wildlife research and conservation and has been working with bats since 2014. She has a B.S. in Ecology from Boise State University and an M.S. in Conservation Biology from Texas State University. She resides in San Antonio, Texas, where she is within a half hour drive to Bracken Cave and spends her spare time exploring the hill country with her dog.  

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