Austin's Bizarre - But Ubiquitous - Bats

Many people watch Austin's bats, but few know their story

Austin Bats
••• Sometimes, Austin's bats emerge just after sunset, as seen here. Robert Schrader

Austin is quickly becoming one of America's hottest cities not only for living and working, but also for visiting. One of the most popular attractions in Austin, whose city slogan is the very apt "Keep Austin Weird," are the bats living under the Congress Avenue Bridge in downtown. In spite of how many people stand on and under the bridge each night to watch the bats emerge, much of bats' backstory remains a mystery.

Where Do Austin's Bats Come From?

Austin's bats have been living under the Congress Avenue Bridge almost since it opened in 1910, but their actual origins are a bit further south – of the border, to be specific. These Mexican freetail bats, not surprisingly, originate in central Mexico, from which they travel northward in the spring months. Austin is only one of the places where the bats go, but their decision (or happenstance) to live under such an iconic symbol of the city has made Austin's bats by far the most famous.

The most famous, and the largest – the world's largest urban bat colony, in fact. Biologists estimate that as many as 1.5 million bats live under Austin's Congress Avenue Bridge at any time, although this number is slightly higher near the beginning of summer when the bats, which are primarily female, give birth to babies.

Where Do the Bats Go?

During a special taping of the Jimmy Kimmel Show for the South by Southwest festival, actress Julia Louis-Dreyfus proclaimed that the bats went to a "mall in San Antonio" each night, further quipping that she'd brought her dress there.

While Louis-Dreyfus' comments made for good comedic fodder, they had no basis in science.

In fact, the specifics of bat that lives under Austin's Congress bridge has a maximum range of around 20 miles, a distance it flies each night in search of the insects and other pests it feasts on. The bats' whereabouts and behavior at night might not be as funny in real life as they are on late-night TV, but they shine a light on the important work the bats do for the city – there would be a lot more mosquitos if they didn't exist, for example.

It is only after Austin's summer temperatures cool off that the bats fly long-distance, back to central Mexico where they live all winter. Then, they return in spring, repeating the cycle over again, to the delight of increasing throngs of Austin tourists.

When is the Best Time to See Bats in Austin? 

The bats arrive in Austin from Mexico in mid-spring, usually during the last week of March or the first week of April, and stay through October or November. While it's more comfortable and convenient to see the bats during summer, when temperatures are higher and the sun stays up longer, the display tends to be more beautiful when temperatures are cooler, and Austin's iconic "Violet Crown" sunsets illuminate the night sky.

As far as how to best observe the bats, that depends on you. The Congress Avenue Bridge is a short walk from many Austin hotels and once you get there, you can either stay up on the bridge or walk just below it, onto the Lady Bird Lake trail. You could even kayak or canoe out beneath the bridge, to get an up-close and persona look – just watch for bat droppings!

Keep in mind that bat sightings are not guaranteed, no matter which time of year you visit, and the timing isn't always exact.

Bats sometimes some out just before sunset, but just as often right after. Some speculate that bats can sense the weight of tourists on top of the bridge, so watching them on a less-crowded weeknight might be a better bet than watching them on the weekend.