As the sun begins to set over Lady Bird Lake, a familiar sight takes place in the skies of Austin, Texas. Millions of bats emerge from under the Congress Avenue Bridge, creating an incredible spectacle that draws tourists and locals alike.

But why is this happening? Why are there so many bats in Austin, and why specifically at the Congress Avenue Bridge?

The answer lies in the fact that Austin sits at the intersection of two major migratory routes for bats. Every year, between March and November, millions of bats make their way north from central Mexico to take up residence in the city’s urban areas. These bats are attracted to the warm climate, plentiful food supply, and abundance of roosting sites, which Austin immeasurably checks the box for each.

But why the Congress Avenue Bridge? Constructed in 1910, it wasn’t until the 1980s that the bridge became home to the largest urban bat colony in North America, with an estimated 2 million bats calling it home. It turns out that the bridge’s crevices and expansion joints provide an ideal habitat for the bats to roost during the day. This, combined with its south-facing location and proximity to water, has made it the ideal spot for bats to call home.

And what species of bat calls the Congress Avenue Bridge home?

Mexican free-tailed bats are the species that call the Congress Avenue Bridge home. They migrate to Austin from Mexico in the early spring and summer months to give birth and raise their young. The bridge’s concrete crevices provide the perfect temperature and humidity for the bats to roost comfortably during the day. Additionally, the bridge’s south-facing location and proximity to water make it an ideal spot for the bats to emerge from at night when they go out to hunt for insects.

Over time, the bat colony grew larger and larger, and the nightly emergence of the bats became a popular attraction for locals and tourists alike. Today, the Mexican free-tailed bats are an important part of Austin’s ecosystem, providing natural pest control by eating up to their weight in insects every night. They also contribute to the city’s tourism industry, with thousands of visitors coming to see them each year.

But it’s not just about the bridge. Bats are an important part of Austin’s ecosystem, playing a vital role in keeping the city’s insect population in check. In fact, a single bat can eat up to 1,000 mosquitoes in an hour! Without the bats, Austin would be overrun by insects, making outdoor activities virtually impossible.

So, the next time you’re in Austin and witness the breathtaking sight of millions of bats taking flight, remember the important role these creatures play in the city’s ecosystem. And if you’re lucky enough to be in town between March and November, be sure to catch the show at the Congress Avenue Bridge.

It’s a bat-acular experience you won’t soon forget!