Two Austin residents moved back into their old homes Saturday after making full recoveries at rehab. Their names were Arlo and Willie, and they're Mexican free-tailed bats. Austin Bat Refuge (ABR) saw them off under the Congress Avenue Bridge just after dusk and is releasing some more of its temporary residents Tuesday, March 11, and Friday, March 14.

Some attendees also got to try an innovative art project for understanding echolocation using extended reality. The XR exhibit at South by Southwest (SXSW) has concluded, but the app can be downloaded via the Apple Store.

Stepping in to help
Austinites who find a bat where it shouldn't be — for example, on the ground outside — have more options than calling animal control. Found bats are often euthanized, but ABR sees another way. In fact, when preparing for Amplify Austin Day this month, the rescue shared that its rehabilitation efforts have reduced euthanasia by 60 percent.

To test a bat for rabies, it needs to be dead because the procedure uses brain tissue in a lab. Bats certainly can have rabies — although the occurrence is really less than one percent of the population, per the U.S. National Parks Service. However, ABR co-founder Dianne Odegard emphasizes that bats are not carriers of rabies, meaning that the disease cannot be symptomless.

If a bat gets rabies, Odegard says, it will die quickly, and she can help ease its transition by euthanizing it humanely herself. The staff is up-to-date on vaccinations and still wear thick gloves while handling its residents.

A tiny friend eating a snack in a gloved hand.Photo courtesy of the Austin Bat Refuge

Arlo and Willie's adventure
Visitors during SXSW got to watch the bats depart after dusk and a feast of mealworms, ensuring that they had enough energy to stay healthy and reintegrate into the colony. It's mating season, so co-founder Lee Mackenzie congratulated the two male bats on joining the colony and meeting lots of females.

Mackenzie held each refugee in between two fingers in a gentle pinching shape, let them stretch out their wings, and then released them into the wind. Spectators were allowed to stand in a line closer to the source of the wind (in the opposite direction of the bats' flight path). It took Arlo two tries to take off, but Willie got it right away.

It wasn't much of a going out night for most of the bats already living under the South Congress Bridge though, though. They started to head out in their dramatic stream, but turned back because of the wind. Mackenzie explained that the colder temperature had less of an effect on their decision, and they're used to sound from a nearby concert on Auditorium Shores.

In fact, noise from people below and cars above is actually healthy for the colony because it keeps away predators that prefer seclusion, like hawks and owls.

Meet a bat
Learning more about bats can be healthy for Austinites who might hold some fears or misunderstandings of the species. It also helps the team to meet people. Mackenzie assured visitors that they like bringing their info table to the bridge — which they do every Friday and Saturday night, seasonally — because it helps "recharge" their social batteries after spending so much time working alone.

If people want to meet a bat, all they need to do is head to that table. The refuge has some long-term residents that are used to meeting people, so they don't get overwhelmed when onlookers crowd around. A staff member clutches each bat tightly in their gloved hand, sometimes gesturing while speaking as the bat goes along for a little ride.

Understanding through art
Attendees at the bat release also got to try an extended reality (XR) project by ABR volunteer and artist Jiabao Li called EchoVision. Odegard and Mackenzie got to experience it for the first time at the bat release, and then it moved to a larger exhibit at the Convention Center where other XR projects were displayed in an expo format.

To help simulate echolocation, Li designed a headset replacement that's like a geometric bat mask that a user holds up with two long handles. The phone screen goes in front of the person's eyes — although hilariously, the display works using reflections that meant anyone nearby can see the user's eyes seeming to stare intently right at them.

An iPhone then clips into the mask and uses its lidar sensor (for measuring depth with lasers) to determine where people and objects are. As a user shouts, speaks, whoops, clicks, or makes any other sustained noises, shimmering, heat map-like shapes begin to form in the display.

Users trying the program at the bridge gasped at the beautiful interpretation of a sense foreign to humans. There was some artistic leniency, since we can't know exactly how echolocation feels without doing it. However, more scientific principles influenced the visuals.

"We first started with black and white," said Li, "and then I read from Ed Young's book An Immense World — my highest recommended book — [that] when bats echolocate, they not only just see the 3D kind of reconstruction of the word, but also textures and even color. And there's even red shift and blue shift, kind of like the Doppler effect."

At the bridge, users were mostly finding other people through EchoVision, but in the XR expo space, they could also explore a "cave" to get more of a sense of place.

Li also brought a haptic feedback couch — one using effects like vibrations and other tactile elements in response to audiovisual stimulus — to enhance a program she described as being "like a bat karaoke." Borrowing bat sounds recorded and categorized by researchers in Israel using artificial intelligence, Li and musician Matt McCorkle composed some musical soundscapes presented in Nocturnal Fugue.

Sound categories somewhat whimsically described by artist (who the whole time was wearing a headband with tiny bat wings sticking out of it) included "mating, fighting, kissing, [and] Mom bats talking to baby bats."

If you look through Li's portfolio of work, she has a long background working with animals. In the case of bats, it was these sounds that drew her interest.

"I think what I found very attractive [about bats] is the way to echolocate that is so different than how we navigate the world," she said.

"I got fascinated by bats. I volunteered at the Austin Bat Refuge. I learned from [famous local researcher] Merlin Tuttle. I joined the bat survey and bat house building. And so I just keep thinking about bats. I can't stop thinking about them. And then this idea comes up: 'Okay, well, what if we can be a bat?' ... That's how EchoVision comes together."