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It's peak bat season at the world’s largest bat colony, right in the Texas Hill Country

15-20 million Mexican free-tailed bats flying around Bracken Cave on Aug. 24, 2023 during a Media event. The bats are preparing to journey to Mexico in October.
Patricia Lim
/
KUT
15-20 million Mexican free-tailed bats flying around Bracken Cave on Aug. 24, 2023 during a Media event. The bats are preparing to journey to Mexico in October.

Bats in North America face a daunting list of challenges. Pesticides kill off the bugs they need for food, climate change disrupts their ecosystems and white nose syndrome — a deadly disease caused by an invasive fungus — threatens some species with near-extinction.

Despite all those challenges, you can still find active colonies all around Texas. And, for migrating species like the Mexican free-tailed bats, late summer and early fall is peak season for viewing.

By late August, bats born earlier in the year are big enough to fly. Their numbers swell the ranks of the colonies that pour out nightly from roosts all around the state.

 "Bats only beyond this point" sign at the Bracken Cave on Aug. 24, 2023.
Patricia Lim / KUT
/
KUT
"Bats only beyond this point" sign at the Bracken Cave on Aug. 24, 2023.


Soon, the majority of these bats will depart to happier hunting grounds south of the border, returning next year in reduced numbers. But, for the time being, this new generation living and hunting along with their parents means the colonies are bigger than at any other time of year.

The world's biggest colony can be found right outside of San Antonio.

 Mexican free-tailed bats held by a scientist at the Bracken Cave Media Event on Aug. 24, 2023.
Patricia Lim / KUT
/
KUT
Mexican free-tailed bats held by a scientist at the Bracken Cave Media Event on Aug. 24, 2023.

Bracken Cave Preserve is home to between 15 to 20 million bats. It's recognized by Guinness World Records as the largest bat colony in the world.

The creatures emerge nightly from the cave in a tornado of leathery wings that spins upwards and unwinds into a massive ribbon of bats streaming to the horizon in search of insects. The colony eats about 400,000 pounds of bugs a night.

15-20 million Mexican free-tailed bats flying out of the Bracket Cave on Aug. 24, 2023 during a Media event. The Recovering America's Wildlife Act, a federal bill under consideration by Congress would help help preserve this cave.
Patricia Lim / KUT
/
KUT
15-20 million Mexican free-tailed bats flying out of the Bracket Cave on Aug. 24, 2023 during a Media event. The Recovering America's Wildlife Act, a federal bill under consideration by Congress would help help preserve this cave.


While the bats come out to feast, others feast on them. On a recent night, hawks crashed into the hordes leaving the cave, flapping away with squeaky snacks. Barred owls swooped silently among the trees along the bats’ flightpath, while snakes slithered toward the bat cave entrance in search of unfortunate fallen flyers.

There are so many millions of bats that it takes hours for the cave to empty.

15-20 million Mexican free-tailed bats flying around Bracket Cave on Aug. 24, 2023 during a Media event. The bats are preparing their way to Mexico in Oct.
Patricia Lim / KUT
/
KUT
15-20 million Mexican free-tailed bats flying around Bracket Cave on Aug. 24, 2023 during a Media event. The bats are preparing their way to Mexico in Oct.


Bracken Cave, managed by the group Bat Conservation International, isn't a place visitors can stop by unannounced. But BCI does offer reservationsevery year. They're mostly for people who have paid a $45 membership fee, but the group saves some spots for the general public.

If you can’t make it to Bracken Cave, keep your eyes peeled. Mexican free-tailed bats roost all over Texas in caves, highway overpasses and bridges, like Austin’s Congress Avenue bridge, where the city's famous urban bat colony lives.

They may be closer than you think!

Copyright 2023 KUT 90.5

Mose Buchele is the Austin-based broadcast reporter for KUT's NPR partnership StateImpact Texas . He has been on staff at KUT 90.5 since 2009, covering local and state issues. Mose has also worked as a blogger on politics and an education reporter at his hometown paper in Western Massachusetts. He holds masters degrees in Latin American Studies and Journalism from UT Austin.
Patricia Lim