August sunsets are special in Austin. Not only do they offer a slight reprieve from the scorching heat, but they also signal to the newest members of North America's largest urban bat colony that it's time to take flight.
Each spring, an estimated 750,000 female Mexican free-tailed bats migrate to the Ann W. Richards Congress Avenue Bridge where they settle in to breed and enjoy warmer weather.
By mid-summer, the bat population under the bridge doubles as the females welcome their offspring. Each female generally gives birth to one pup, according to Texas Parks and Wildlife. By early August, after weeks of maternal care, the baby bats spread their wings and emerge nightly from the bridge alongside their moms in search of food — creating an iconic sunset show that draws visitors from around the world.
Oscar Alvaravo, an international student visiting from Mexico, felt a little unsure about seeing the nocturnal mammals take flight, but once he saw the colony emerge from beneath the bridge, he was impressed.
"I think it was pretty amazing. It felt like a 'Batman' movie," Alvaravo said as the sun set over downtown Austin.
There certainly is something cinematic about witnessing the flurry of bats ascend into the darkening sky, but behind the visual spectacle, the baby bats face a tough journey of growing up.
Dianne Odegard, co-founder of Austin Bat Refuge, says that after bat pups graduate from weeks of intense maternal care, they can struggle.
"It's hard to be a baby bat," Odegard said. "They have to really avoid a lot of obstacles and a lot of threats for them to be able to grow up and be a successful adult."
Lee Mackenzie, also a co-founder of Austin Bat Refuge, points out that newly-flying bat pups have to navigate a complicated series of events from the first moment of flight.
"When they make the faithful leap to let go of their bridge crevice for the first time, they have to do everything right all at once," Mackenzie said. "They have to fly in the first 40 feet and not get lost and not get eaten by a predator. Find some food. Find water. Come back and find the roost again."
It's not always a smooth process. Bat pups can struggle with the heat, get lost or not find enough insects to eat, according to Mackenzie. And that's why, this time of year, you're more likely to see a grounded bat.
If you find a grounded bat, Austin Bat Rescue urges people not to touch the bats, but to also not neglect them. The nonprofit organization rescues and rehabilitates the animals, while also offering guides and telephone advice for bat encounters.
"If you see some on the landscape at this time of year, be kind to them," Mackenzie said. "They're just little pups trying to figure out how to be adults."
You can watch the bat pups and their mothers' nightly emergence from several free pedestrian areas near the Congress Avenue Bridge or from a tour boat on Lady Bird Lake. Austin Bat Refuge keeps a daily log of the bat flight times and viewing tips.
The bats begin their migration back to Mexico in the fall.
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