check this video out. all these little ones heading out
At dusk, 20 million Mexican free-tail bats would pour from the darkness inside Bracken Cave on the outskirts of San Antonio, Tex., in a skillfully crafted black tornado against the dimming orange sunset. But a few thousand feet away, directly in their flight path, a community of 3,500 homes would soon stand.
That was the plan at least, until Halloween.
In an effort to protect both bats and would-be residents, The Nature Conservancy of Texas and Bat Conservation International — with help from other groups, including the Department of Defense and the City of San Antonio — purchased the land for $20.5 million, providing a buffer between the bats and the encroaching urban sprawl.
The 1,521-acre plot called Crescent Hills is roughly 30 minutes northwest of San Antonio. The area is adjacent to the famous bat cave and lies within the Edwards Aquifer recharge zone. The aquifer provides drinking water for roughly 2 million central Texans, including the entire city of San Antonio. The property is also home to the federally endangered golden-cheeked warblers, birds known locally as golden finches of Texas that nest in the area.
A view from inside Crescent Hills, the proposed site of a housing development, near San Antonio. CreditJerod Foster
“This is a major step forward in balancing growth and conservation in these sensitive areas,” said Ron Nirenberg, a member of the San Antonio City Council.
The cave itself is within a preserve, but Crescent Hills sits right on the edge of the preserve. When the housing development was first proposed, Bat Conservation International, which owns Bracken Cave, and the Nature Conservancy of Texas, argued that the bats could pose a threat to the new neighborhood.
“The bats have a very low flight path, and the homes would be located in what is the equivalent of the airport runway for the bats,” said Laura Huffman, director of the conservancy in Texas.
The cave is home to the world’s largest colony of Mexican free-tail bats and accounts for one-fifth of their entire population in the United States. Each evening, the bats begin a three-to-four-hour flight out of the cave in waves, fanning out over Texas’ vast corn, cotton and other agricultural fields. During their flight, biologists estimate that the colony eats an average of 100 tons of insects each night, reaching a peak of 140 million during the summer months. Nationwide, as a natural pest control, the bats save farmers $23 billion annually in reduced crop damage and pesticide use.
Mexican-free tail bats leaving Bracken Cave near San Antonio, Tex. CreditJacqueline Ferrato/The Nature Conservancy
“They are eating the adults so they actually have a magnified effect,” said Mylea Bayless, Bat Conservation International’s director. A study done on an eight-county agricultural region in central Texas, found that the Mexican free-tail bats in Texas prevent crop loses and cut pest management costs by an estimated $741,000 per year. The profit margin for crops like cotton and corn can be very tight. “For many of these farmers, the insect pest control services of the bats could mean the difference between profit and loss for them,” Bayless said. “The economic value of these bats for agriculture is really important.”
The bat cave has become a popular landmark for local Texans. Because of the massive quantity of bats flying at once, they often show up on Doppler radar and local television stations jokingly acknowledge that the blip is not rain, its just the bats. For years, the bat conservation group has provided tours where groups can watch the bats’ evening ritual up close.
“People have started to value the bats and understand their importance in our ecosystem,” Ms. Bayless said. “Bats always get a bad rap on Halloween, so we thought it was appropriate for the bats to win at least once on Halloween.”
Working with the conservancy, her group raised $5 million through private donations to buy the land. The city of San Antonio provided an additional $10 million, in part through a voter-approved program designed to protect water quality in the Edwards Aquifer. The United States Army also contributed $100,000 to the fund in part to protect the habitat for the golden-cheeked warbler.
“We were really proud to be part of this transaction,” said Jim Cannizzo, an attorney adviser for Camp Bullis. “For both the Warblers and for the bats, which are well known in this community.” Camp Bullis is in a designated refuge area for the endangered species and the Army has been actively involved in protecting this species, monitoring where they build to limit encroachment on the warbler habitat.
The Nature Conservancy will manage the property and plans to create hiking trails and invite the public to watch the bats. Ms. Huffman hopes the sale will provide a model for future conservation efforts. “This shows a new way to do conservation in an urban area,” she said. “The fact that we accomplished so many conservation goals is truly incredible.”
Correction: November 7, 2014
An earlier version of this article referred incorrectly to golden-cheeked warblers. The birds are known colloquially as golden finches of Texas, but they are not a species of finch.