Petition Closed
Petitioning San Antonio Mayor, City Council, Planning Commission

San Antonio: Save Bracken Bat Cave, Stop the Crescent Hills Development

One of the worlds’ top ten wildlife spectacles, and the only one in the United States, is now threatened!


Bracken Cave, the world's largest gathering of bats, is an unparalleled living natural wonder. The emergence of its 10 million+ bats from Bracken cave is a one-of-kind sight. Now we need your help saving it! Galo Properties has proposed a large-scale, high density community along the Bracken Cave Reserve’s border that would place 3,800 homes—approximately 10,000 people—next to colony and under the twice daily flight path of millions of bats! This would be a situation sure to put people and bats into conflict. Not only would the proposed Crescent Hills community be potentially detrimental to the bats and the multi-million dollar pest control services they provide for Texas agriculture, it would also lie atop the sensitive Edwards Aquifer-recharge zone, threatening Central Texas’ water supply and the millions of public dollars invested in protecting it. The federally endangered Golden-cheeked Warbler also calls this area home, nesting and foraging on the land slated for building. Tell the San Antonio City Council, Mayor, and Planning Commission that Mr. Galo's proposed subdivision is an incompatible use for the land in this area.

For more information about this issue, visit www.batcon.org/savebracken.  

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Letter to
San Antonio Mayor, City Council, Planning Commission
We urge you to declare Galo's proposed community next to Bracken Bat Cave an incompatible use of land.

Bat Conservation International (“BCI”) is a not-for-profit corporation organized under section 501(c)(3) of the Internal Revenue Code. We are a scientific and educational organization dedicated to the study and conservation of the world’s 1,263 known species of bats. We work throughout North and South America, Africa, Asia and the Pacific. Our roots, however, are here in Texas where we have been headquartered since 1986 and continue to do significant work.

BCI owns 697 acres bordering the former Dierks Tract in Comal County, the proposed site of a 3800-lot development by Galo Properties. We manage our site as the Bracken Bat Cave Preserve. The preserve has significant value for education and research and is presently used by students and faculty of Texas A&M, Texas State, the University of Texas and other institutions.

BCI considers the current design and density of the proposed development an incompatible use that negatively impacts the ecological significance of the Bracken Bat Cave Preserve, and would also have a negative impact to human health and safety. Bracken Bat Cave Preserve is home to the largest known colony of bats in the world. Bracken Bat Cave houses a maternity colony of at least 10 million adult Mexican (sometimes called Brazilian) free-tailed bats, Tadarida brasiliensis, which leave each night to
forage over the woods and fields of south-central Texas. Young bats are born and raised in the cave and learn to fly and forage in the immediate surrounding area. Mexican free-tailed bats were recognized as the official state flying mammal in 1995 and are designated as a “species of greatest conservation need” by the Texas Parks and Wildlife Department in their recently updated Texas Conservation Action Plan.

The nightly mass emergence of the free-tailed bats is one of North America’s most vivid natural phenomena. As primary predators of night-flying insects, the bats are critical to maintaining low regional levels of many insect pests. A free-tailed bat can eat its body weight in insects each night, consuming for example vast numbers of corn earworms and cotton bollworms, which damage cotton, corn and other staples of Texas agriculture. The Bracken Bat Cave colony in fact consumes up to 100 tons of insects each night. A 2006 study of eight south-central Texas counties estimated that free-tailed bats alone save cotton farmers approximately $750,000/year, nearly 30 percent of the total value of the cotton crop from those counties, making the bats, in essence, the difference between profit and loss for those Texas farmers. A study published last year in the journal Science estimates the average annual value of bats to all U.S. agriculture at $23 billion/year in pest control.

Preserve is the basis of the following concerns.

Human Health and Safety Considerations

1. As much as the members, trustees, volunteers and staff of Bat Conservation International admire and seek to protect bats worldwide for their intrinsic, ecological, scientific and economic value, we must acknowledge the issue of disease. Bats are the primary source of human rabies in North America, and though the incidence of human infection from bats is fortunately rare, situating 3800 families within several hundred yards of at least ten million bats has the potential to put people and bats into contact with one another on a regular basis. This is the same species of bats that occupies Austin’s Congress Street Bridge, and being adapted to using manmade structures, the bats will seek out roosts in the Crescent Hills houses. Pets and children may also encounter sick, dying or juvenile bats, raising the risk of disease transmission.

2. Our preserve contains several karst features in addition to Bracken Cave, as well as historic buildings and a historic mineshaft that accesses the back of the Cave. The mineshaft was drilled and guano was mined for commercial fertilizer in the early 1900’s. Bracken Cave itself lies at the bottom of a half-acre sinkhole with steep, rocky sides. Each of these features, once they become known to the presumed 4000+ children and teenagers living adjacent to the preserve, will become potential sources of accident and injury. Even entering the cave can be deadly because of the concentrations of ammonia and carbon dioxide from the decomposition of the guano. An airborne fungus causing the respiratory disease histoplasmosis is also present throughout the cave. This requires our scientists and land management staff to wear respirators and other protective gear when spending any time at all in the Cave.

3. It’s believed that bats have been using Bracken Cave for thousands of years; the guano is as much as 80 feet deep in portions of the Cave. Guano was, in fact, mined during the Civil War for saltpeter, a required ingredient for the gunpowder of that era. As the Confederacy knew, guano is high in nitrogen and highly flammable in large quantities. A fire that began by accident or arson could burn for decades, destroying the colony and one of Texas’ great shows of nature, with an essentially permanent blanket of smoke and fumes spreading through surrounding properties, creating very difficult conditions for any nearby residents.

Ecological Concerns

1. From the perspective of protecting the bats, we’re fortunate that Mexican free-tailed bats are tolerant of manmade development, as evidenced by the free-tailed bats using Congress Street Bridge in Austin. (The interface between these urban bats and city dwellers is significantly different from what it would be with nearby homes and yards for the bats to forage over near Bracken.) That said, we do not know what the impacts of such dense residential development, with its attendant noise and lights, will be on the bats. At present, when the bats leave Bracken Cave, they fly directly over the Galo Property. The Galo property drains onto portions of our preserve through a series of shallow washes. As the Edwards Aquifer ecoregion is a karst landscape with thin soils covering limestone bedrock, making it prone to flash flooding in heavy rains, we have questions about surface and subsurface drainage from the proposed subdivision and the impact of nutrient, pesticide and herbicide runoff from normal lawn management on the groundwater, subterranean features and fauna of our Preserve. We are considering commissioning hydrogeologic and new subterranean faunal surveys to delineate the drainage basins of all of our karst features and determine whether the Preserve also contains endangered or endemic cave species.

3. One of our most significant reservations about the proposed subdivision concerns our continued ability to use controlled burning to maintain the health, open character and maximum groundwater recharge capacity of the native oak-juniper savannah habitat that typifies the Edwards Plateau. All but a small portion of our Preserve is subject to a 2002 conservation easement held jointly by the Edwards Aquifer Authority and San Antonio Water System that requires us to “preserve the natural condition of the property” and “to protect the property’s natural resources, watershed, recharge water quality, and ecological integrity, and to protect
and preserve native vegetation, habitat and native wildlife, including threatened and endangered species.” The oak-juniper savannah is a fire-dependent community that requires regular burning to maintain its ecological health and biological diversity. Because the proposed subdivision is directly downwind of the preserve, keeping the subdivision smoke-free would be nearly impossible. Experience elsewhere suggests this would make it increasingly difficult to receive the necessary permits to continue controlled burning, eventually degrading the quality of the habitat and its value for aquifer recharge and impacting the multiple pairs of federally endangered golden-cheeked warblers that nest on the Preserve. It would also allow the buildup of dead grasses and downed wood, significantly increasing the possibility over time of an uncontrollable wildfire, started by lightning or human activity. Indeed, the risk of curious children playing with matches along the edge of the preserve is a serious management issue for us, based on what has happened at other nature preserves around the country in fire-adapted ecosystems.

Other Management Considerations

1. Gene Dawson, the engineer for Galo Properties, has told us the company is proposing to erect, at its cost, a secure fence along our common boundary. We very much appreciate this. Unfortunately, it represents only a fraction of the management costs we would accrue as a
consequence of the proposed development. Because of the risk of serious injury to children and other individuals who might be tempted to enter the property regardless of a boundary fence and the sensitivity of the bats to disturbance, it would be necessary for us to erect a significant amount of interior fencing to secure the historic buildings, mine shaft and Bracken Bat Cave sinkhole and possibly other karst features on the Preserve. Without question, we would also need to build a manager’s residence and hire an on-site manager to provide a 24/7 human presence. Even with this $500,000+ investment that the Crescent Hills subdivision plan would compel us to make, we cannot assume this will be sufficient to prevent all occurrences of trespass and the types of consequences outlined in this letter. Nor would it address the bathuman interactions that are certain to occur within the Crescent Hills subdivision. The proposed development thus significantly increases the possibility that Bat Conservation International and perhaps other parties would be sued if, despite all precautions, some tragedy occurs on or off our property.

In short, Bracken Bat Cave Preserve is not like other nature sanctuaries. As the world’s largest bat colony, it is unique and presents equally unique management challenges that must be taken into account in determining the appropriate use of adjoining properties. We urge you to declare Galo's proposed community next to Bracken Bat Cave an incompatible use of land.

Thanks very much.