How will Austin & San Antonio bats react to the April total solar eclipse?

In two weeks, the moon will block our view of the sun creating a rare total solar eclipse. The sudden darkness can confuse animals and change their normal behaviors. To document what happens, scientists will be monitoring a wide range of animals including nocturnal bats. Do they wake up, take flight, start foraging? No one knows exactly what will happen, but Central Texas is the place to find out.

Every night, millions of bats create a jaw-dropping sight at Bracken Cave Preserve on the outskirts of San Antonio. Just before sunset, a river of Mexican free-tailed bats spirals out of the cave in what many think looks like a bat-nado.

“Bracken Cave, behind us, is home to the largest colony of bats in the world,” said Fran Hutchins, Director of Bracken Cave Preserve.

Hutchins is as close as Central Texas gets to having its own bat man in charge of a bat cave.

“The population, at its peak, is around 20 million bats,” said Hutchins.

That is about 18 million more bats than fly out from Austin’s Congress Avenue Bridge to grab a dinner of insects.

“The Congress Avenue Bridge is the largest urban colony of bats. So, you have about a million and a half bats at Congress Avenue Bridge,” said Hutchins.

By April 8, many bats will have completed their migration from Mexico back to Austin and San Antonio.

“During the eclipse, we’ll probably have at least half of our populations of bats between Congress Avenue Bridge and Bracken Cave,” said Hutchins.

The giant roosts make Central Texas the ideal spot to monitor the reaction of bats and the animals that prey on them during April’s total solar eclipse.

“It doesn’t happen very often and it’s just something interesting to see how the animals react to something changing in the environment,” said Hutchins. “The raccoons or skunks could come out thinking that the bats will be flying out and they are looking for something to eat. We also have a lot of raptors that feed on bats at these bat roosts. So, they may show up early thinking that it is getting dark and it is time for bats to come out.”

At Bracken Cave, Hutchins and other experts will be walking the perimeter of the cave monitoring any change in behavior. But since the bats are already underground in a dark environment, they are less likely to notice the moon completely blocking the face of the sun.

Where scientists think there could be a bigger reaction is Downtown Austin. The bats roosting underneath the Congress Avenue Bridge are more likely to notice day is temporarily becoming night. Experts are not sure what the nocturnal bats will do, but the possibilities range from not noticing to becoming confused, anxious, or even flying out to see what the fuss is all about.

“I guess start swarming,” said Jessica Manner as she walked across the Congress Avenue Bridge. “I don’t know enough about bat behavior to really know, but I could see them starting to do their thing.”

“Maybe like flap around a little, like they think it’s nighttime,” said Lilly Young as she stood on the bridge. “I am curious to see.”

NASA is also curious and not just about bats. The Eclipse Soundscapes Project will monitor atypical animal behaviors in Central Texas and along the entire eclipse path.

“They’re recording insect, animal, bird and bat sounds before, during and after the eclipse to see if there is any change in behavior,” said Hutchins.

In addition to the Mexican free-tailed bats, there are seven other bat species in the Hill Country. Many of them roost in trees and around 1:30 in the afternoon on April 8th they could take flight and start to forage, or they could have a much less dramatic reaction.

“They might stir around and look just to see what is going on,” said Hutchins.

At Bracken Cave Preserve, one square foot of the ceiling can contain 500 bats. They are packed in, just like the throngs of people expected to converge on Texas in April. Experts say do not be surprised if humans have a more impressive reaction than bats.

“They have been out foraging for food all night long so that is normally when they are sleeping. So, they may not even wake up. Sorry,” laughed Hutchins.

To watch a live camera at the entrance to Bracken Cave click here.