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3D-printed tortoise shells could help save this threatened species

Biologists are using 3D-printed, fake tortoises to learn more about raven attacks and discourage the predators from feasting on desert tortoises.

3D-printed tortoise shells could help save this threatened species
[Photo: Hardshell Labs/courtesy Autodesk]

If you happen to be wandering the Mojave Desert and come across a desert tortoise, don’t poke around the critter too closely—you could end up covered with a surprise spray of artificial grape fluid. That’d be because that tortoise is a 3D-printed imposter, and it thinks you’re a raven.

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Thanks to human activity, ravens have invaded the deserts of the western U.S., taking a toll on its ecosystems and threatening the desert tortoise in particular, preying on juveniles before their shells are fully formed. In an effort to save populations, a biologist has teamed up with engineers to forge a 3D-printed, lookalike baby tortoise that allows them to gather data on raven strikes—and to counter-attack with a non-toxic spray. He hopes the “techno tort” partnership could serve as a template other biologists could use to solve certain conservation crises.

[Image: Hardshell Labs/courtesy Autodesk]
Ravens are considered a native invasive species. They’ve proliferated by 700% in the past 25 years due to expanded human presence in the desert, providing opportunities that didn’t previously exist in the hostile environment: highway roadkill and trash are now food, while billboards and transmission towers are nesting structures. Tim Shields, a field biologist with more than 30 years’ experience studying tortoise behavior and populations, Zoomed into a call with Fast Company from his car outside Victorville, California, on the southwestern edge of the Mojave Desert. “I’m looking at a landscape that has been transformed,” he says. “I’m looking at nothing but opportunities for ravens.”

[Photo: Hardshell Labs/courtesy Autodesk]
Ravens eat well. They feast on burrowing owls; the colorfully named Coachella Valley fringed-toed lizard; and on young tortoises, which ravens eat by poking their beaks through soft shells as the tortoises surface to escape scorching ground temperatures. They have little choice but to emerge: In the spring, juvenile tortoises must go out and eat to help ossify their keratin shells, since the bone will make them more immune to predation in the long run. But by doing this for 8 to 15 years of their early lives, they then risk raven attacks. Desert tortoise populations have reduced by at least 90% since the 1980s, and are officially listed as threatened—though Shields says they should be in the endangered category.

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[Photo: Hardshell Labs/courtesy Autodesk]
Enter the “techno tort,” a counterfeit tortoise made to dupe ravens. The concept has been underway for more than a decade by Hardshell Labs, Shields’s company that uses technology to conserve indigenous wildlife against avian damage. It was the ingenuity of a high school student in Shields’s native Alaska that led to the team 3D-printing a shell, which was then improved by Autodesk, a software corporation that’s one of the leaders in computer-aided design (CAD). Hardshell used the company’s CAD tool, Fusion 360, to 3D-print a hard, plastic-resin shell, painted to resemble the baby critters. They turned out to be lifelike. “I fool professional biologists with these things all the time,” Shields says. “I fool myself.”

[Photo: Hardshell Labs/courtesy Autodesk]
It was crucial for them to be realistic in order to fool ravens. The knock-off tortoises can track ravens poking around at them with their internal sensors and cameras, and collect data about when, where, and how ravens are attacking, and about the severity of the threat. Previously, Shields’s research relied on happening upon random dead shells, which was forensics rather than a quantitative, “scientifically rigorous demonstration,” he says. They deployed these shells en masse in 2018 and 2019, and have sold about 1,000 to the U.S. Fish and Wildlife Service. Using the data collected from their fake tortoises, Shields’s team determined that a single raven per 2.5 square kilometers in the desert will ensure the localized extinction of tortoises. “The odds of that little guy evading detection by a raven, in the period of time necessary for maturation, is essentially zero,” Shields says.

Now, some of the dummy torts fight back. Cornerstone Research Group, a defense manufacturing company, has installed electronic accelerators and canisters of liquid inside the shells. If ravens get aggressive, the shells will spray a non-toxic irritant called methyl anthranilate, an artificial grape flavoring that repels birds. “Ravens don’t like surprises,” Shields says, citing their high degree of neophobia, or fear of anything new. The idea is that they “shock the bejesus out of them, so that this is burned into their brain,” and that they hopefully communicate the danger to their young. “We’re trying to essentially insert a meme into raven society, and hopefully it spreads,” he says.

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[Photo: Hardshell Labs/courtesy Autodesk]

Hardshell is now testing how the weaponized prototypes fare in that “sting operation,” having trialed 5 last year and another 10 this year. Shields is energized by the collaboration, and believes tech is the way to tackle growing conservation catastrophes. On the other side, there are engineers who often work on dry problems, but who are energized by the tortoises. “Autodesk went gaga for this,” he says. “They’re so freaking cute.”

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[Photo: Hardshell Labs/courtesy Autodesk]
For years, Hardshell has targeted ravens with other tech-based solutions, including using laser lights to deter them from habitats, and a procedure they call “remote egg oiling.” Nozzles mounted on aerial drones apply a non-toxic oil onto raven eggs, which prevents oxygen exchange so they don’t hatch. But they remain undamaged, so ravens keep incubating them and don’t re-nest, helping to reduce reproduction, and curb populations.

The next step will be to get ahead of inquisitive ravens by making the dummies even more deceptive. “When you’re dealing with an animal as smart as a raven, you don’t want to stake everything on the current behavior of the animal, because they they are very flexible,” Shields says. He wants to make a robot tortoise that can move, or whose head can poke out and wiggle. The team may also consider other aversive tools, including meat baits soaked in a chemical called carbachol, that would trigger a nasty case of food poisoning, a visceral reaction which is enough to drive us away from tasting certain foods again.

He’s toyed with making the techno torts into a game. Remotely, gamers could control the booby-trapped shells, and potentially fire the irritant. “Environmentalism based on the joy of games is a winner,” he says. “Environmentalism based on guilt feelings is a loser.” Ultimately, he wants to find the best tools to draw people away from their screens and back into nature, and to get them to care about conserving it. “Any game a human can construct is a pale shadow of what ecosystems do all the time,” Shields says. “We ought to be madly in love with this planet.”

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