FAQS: About Austin's Bats

When people talk about Austin’s bats, they're usually referring to the world-famous colony that lives under the Ann W. Richards Congress Avenue Bridge. The species is officially known as the Brazilian free-tailed bat, although many still refer to them as Mexican free-tails. Whatever you call them, just remember — they appreciate it if you don't shine bright white lights on them while they’re emerging each evening

How many bats live under the bat bridge in Austin?

Each summer, the Congress Avenue Bridge in Austin becomes home to an impressive colony of up to 1.5 million Brazilian free-tailed bats. This makes it one of the largest urban bat colonies in the world — a breathtaking sight when they emerge at dusk.
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Why do bats like living under a bridge in downtown Austin?

The expansion of the Congress Avenue Bridge in 1982 resulted in deep, narrow spaces that act as a natural incubator for the naked newborn pups. The intense heat absorbed during the day releases slowly at night, creating a warm microclimate so the mums in this maternity colony don’t have to expend as much energy to stay warm.
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Do the bats live under the bridge all year?

Although many bats migrate south each fall, a portion of the colony — as many as 100,000 individuals — stays under the bridge all year. Even in mid-winter, you might catch tight, column-shaped emergences as they head out to feed. The true highlight of bat season, though, is late July through August, when up to 1.5 million bats take to the skies as the pups join their mothers on nightly flights.
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Most of the source data for these FAQs can be found on the website maintained by Merlin Tuttle’s Bat Conservation: https://www.austinbats.org/

How much money do bats save Texas farmers?

Free-tailed bats in Texas save farmers more than a billion dollars annually in avoided pesticide use. 
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Much more to come! Last updated 7/25/26