Scientists fight for an endangered tortoise with a secret weapon : lasers
Human impact and a booming bird population are devastating the Mojave desert tortoise. But one man is trying some unusual methods to save them
A baby desert tortoise is no match for a raven. The tiny reptile’s soft shell is easily pierced, offering the bird a tantalizing fix of delicious entrails.
But not if tortoise biologist Tim Shields has anything to do with it. Shields has dedicated the last four decades to studying desert tortoises in the Mojave desert, and is fighting to save the species with a hi-tech armory comprising robots, lasers, 3D-printed lures and an intimate understanding of his feathered enemy’s modus operandi.
“Historically ravens were rare, but humans have made it very easy for them to survive,” said Shields, who says that the raven population in the Mojave desert has increased 700% over the last 25 years. Humans provide food in the form of agriculture, trash dumps and roadkill as well as cell towers, telegraph poles and billboards that provide safe nesting sites. That means there are a lot more hungry, cawing beaks to feed, particularly during breeding season.
“We have completely overloaded the desert with these highly intelligent predators with a high metabolic rate. They go into predatory overdrive when their eggs hatch,” he said.
The feeding frenzy is indiscriminate. In addition to devastating the desert tortoise, ravens target birds including the sage grouse, snowy plover and the least tern, as well as horned lizards and snakes.
Shields is left to deal with the aftermath, finding dozens of mangled baby tortoise shells as he scours the desert for living specimens. Baby tortoises take up to five years to develop the tough outer shell they need to withstand raven attack. “In the early part of my career, there were hundreds of tortoises per square mile. I’d find and catalogue maybe 15 tortoises per day. Now I’m lucky if I find one,” he said.
Baby tortoise is a ‘luxury item’ for ravens
Shields, through a company called Hardshell Labs, is taking matters into his own hands with a range of technological solutions.
First up: camera-equipped remote controlled rovers that can patrol the desert to keep track of the remaining tortoises while scaring away ravens. Shield’s vision is to have a fleet of these unmanned vehicles that members of the public can control via the internet in order to better understand the species.
“There’s potential to have thousands of eyes in the desert to increase the amount of information we can collect about the tortoises, while engaging more of the public in caring about the species,” Shields said.
He’s collaborating with others including Roy Haggard, a hardware consultant who has worked on a real Mars lander, and electronics engineer Chris Smith, to build a rugged wheeled robot that can navigate the desert and livestream video footage of its travels.
It’s critical the rover doesn’t harm tortoises – something the team has had to demonstrate by running over a baby tortoise without causing any damage.
Shields doesn’t want to hurt ravens either. Instead, he wants to train them by appealing to their cautious and communicative – they learn from each other – tendencies. “You need to hack into their communication system and get them to propagate the message,” he said.
This is where a combination of lasers and 3D printers come in handy.
Ravens can’t stand lasers, so Shields has been using laser rifle scopes to sweep areas of the desert to ward the birds off. “I spent three weeks firing the laser at ravens and they didn’t come back to the area for several weeks after,” he said. The conditioning seemed to work.
The second way to train ravens involves creating highly accurate 3D-printed baby tortoises – which Shields calls “techno-tortoises” – that blast a noxious chemical and sound an alarm when disturbed. A laser could be added as well to create a triple assault on the senses. Other 3D-printed babies could be packed with a tasty lure treated with a substance that induces nausea and diarrhea.
The trials are in their early days, but Shields is convinced he can alter the ravens’ behavior. “Baby tortoise is not an essential food item for ravens. It’s a luxury item. My bet is that the motivation to eat baby tortoises is relatively low in the face of a negative experience. They are very cautious animals, by and large.”
‘It’s a conservation emergency’
Throughout our conversation, Shields talks fondly of individual animals he’s followed over the years, each identified by number rather than name. Tortoise 29, for example, is a powerhouse alpha male who was unexpectedly courteous towards lesser tortoises. “He was killed by coyotes during a drought in the mid-2000s. That was very sad.”
During that same drought, Shields experienced one of his lowest moments when he revisited a plot of land once teeming with tortoises. “We found 398 carcasses and 30 live tortoises. That was very depressing,” he said.
Shields described how he scoured the area in the hope that Tortoise 125 was still alive – sadly he wasn’t.
“He was 325mm, one of the biggest tortoise I’d ever seen. He was like a boulder. I was dreading the day I found his shell. “I almost hung it up at that point.”
The fact that the tortoise grows so slowly, taking about a decade to reach maturity, and has a very low reproductive rate make it harder for the species to recover from the onslaught. To make matters worse, adult populations have been hit by a fatal respiratory disease. “The adults are being hammered by disease and the babies are hammered by ravens,” said Shields. “It’s a conservation emergency.”
The story of the Mojave desert tortoise is a microcosm of a much larger natural crisis, according to a new report by the WWF and Zoological Society of London, which predicts that the number of animals living in the wild will decrease by two-thirds in the next four years due to the impact of humans.
The plight of the tortoises is particularly tragic since the creature has survived in roughly the same form for 220m years, “sailing through” the mass extinction that wiped out most of the dinosaurs.
Their efficient design means they can live in an “incredibly stingy” environment. “I look at my own species and we’re the polar opposite. We’re sloppy with resources, careless and reckless.”
Spending so much time with these creatures has clearly had a profound impact on Shields.
“When I went out to start my career as a tortoise biologist, I was a fairly tightly wound, competitive American male,” he told the Guardian. “Through hanging out with these creatures I learned a much more balanced way of approaching life, just by osmosis.”
“If they were completely wiped out, I would be crushed. It would be hard to take. It’s already been very hard to take.”