COVER: Mexican free-tailed bats depart their roost beneath the Congress Avenue bridge in Austin one evening in 2011. PHOTO VIA FLICKR
by ALEXANDRA PAEZ
For Reporting Texas
Texas is home to some of the largest bat colonies in the U.S., and 13 of them are located in Central Texas. Mexican free-tailed bats dominate the Texas skies in comparison to other species. More than 31 other species of bats live in the Lone Star State.
Bats eat pesky insects, such as mosquitoes, and they’re a tourist attraction in Austin, where visitors gather at the Congress Avenue bridge to watch the critters emerge each night to find food.
Here are ten facts you may not know about bats in Central Texas:
1. The Mexican free-tailed bat is Texas’s official state flying mammal, according to State Symbols USA. The bat received that honor in 1995 under Gov. George W. Bush, who signed a state Senate concurrent resolution that year. A large population of the species is also found in Mexico.
2. The Lone Star State is home to some of the largest colonies of bats in the world. The Congress Avenue bridge, in the heart of Austin, has the largest urban bat colony, estimated at about 1.5 million.
3. San Antonio’s Bracken Cave sports the largest bat colony in the state and in the world. More than 15 million Mexican free-tailed bats migrate to the location, which is less than 20 miles from the San Antonio Riverwalk.
The Bracken Cave is a maternity colony, where expectant mothers roost; the males roost elsewhere. Each year in late June, the mother bats give birth to millions of pups (baby bats), according to Bat Conservation International.
4. Frio Bat Cave is in Concan, just west of San Antonio. “Scientists tell us that we have the second largest bat population in Texas with 10 to 12 million Mexican free-tailed, Peter’s ghost-faced, and cave myotis bats,” said Kirstin Walker of Frio Bat Flight Tours.
5. The Frio cave attracts 3,500 to 4,500 people in March to September, which is the bat breeding season. People watch the bats emerge from a cave on the top of the hill. Hawks and falcons hunt the bats once they exit the cave, according to the Frio Bat Flight website.
“We have a lot of birders. We get a lot of British tourists,” as well as visitors from other countries,” Walker said.
6. White-nose syndrome is a fungus that affects hibernating bats. It invades the bats’ skin, disturbing their hibernation and causing them to use up their important fat stores.
Since the fungus thrives in cold and humid environments, it only affects only 20 out of 32 species of bats in Texas.
At the Frio Bat Cave colony, Peter’s ghost-faced and cave myotis bats are at a high risk of contracting the fungus because of their hibernation patterns.
“I’m hoping that it won’t affect the Mexican free-tailed bats because it doesn’t hibernate,” said Andrew Barnebey, president of the Devil’s Sinkhole Society in Rocksprings. The society arranges tours of the state natural area of the same name.
7. The Devil’s Sinkhole State Natural Area is the largest sinkhole in the state, providing an underground haven for the dominant Mexican free-tailed bat population. Visitors can stand on a platform above the 340-foot-deep sinkhole and watch the bats fly out.
“They come out like a tornado,” said Norma Crowe, volunteer office manager. “When it’s windy, people get slapped in the face sometimes by bats that lose their balance.”
8. Unlike many other locations, the Devil’s Sinkhole State Natural Area offers a morning bat return tour that begins before dawn. Visitors meet the tour guide at the visitor center and convoy to the cavern to watch millions of bats zoom into the sinkhole at speeds more than 60 mph. “It’s amazing every time I see them and I’ve been here three years,” said Crowe.
9. “The way they raise their pups is truly astonishing. You will see millions of moms—dark brown patches—and millions of pups—little pink patches. The mom will go out and feed and when she returns she will find junior once again among the millions of pups, by sound and smell,” said Barnebey.
Mothers must consume more than half their body weight daily to produce enough energy-rich milk for their pups. When female bats have their pups, they can double the population of a colony. After four or five weeks, the pups will attempt to fly. Collisions with other bats can be fatal and at least half of the pups will not survive to adulthood, according to Bat Conservation International.
10. Bats can eat up to 1,000 mosquitoes in one hour. Seventy percent of bat species are bug-eaters, and the rest eat fruit or small animals, reports the Defenders of Wildlife. A bat colony can consume tons of insects in one night, with each bat eating almost their own weight in bugs. In South Central Texas, bats alone may save farmers upwards of $1 million a year in pesticides, reports Texas A&M University on its Agrilife website.
Bats around the world have an important ecological role. They act as natural pest control, pollinators and seed dispersers. More than 1,300 bat species can be found in almost all parts of the world. But in Texas, you will find 32 of the 47 types of bat species known to live in the United States, reports Texas Parks and Wildlife. That is more than any other state.
ANGELA BUENROSTRO reports for Reporting Texas, a UT School of Journalism program, where this story was originally published. It is reprinted here through a news partnership between Reporting Texas and the San Marcos Mercury.