USGS

How Do You Save the Desert Tortoise? Lasers, Robots, and Bureaucracy.

Conserving this ancient and slowly reproducing reptile requires playing the long game.

July 19, 2017

Roy C. Averill-Murray,USFWS/Flickr

Desert tortoises have crawled the Mojave Desert since before there was an America, or a Mojave Desert for that matter. For millions of years, these plodding reptiles have ambled across the sands, gnawing on flowers, grasses, and cacti, digging extensive burrow networks, and every once in a while, creating more tortoises. But today, only 100,000 of these bowling ball–size emblems of the Southwest remain.

Despite their slow reproduction cycles, these tortoises were doing pretty well for themselves until the 1970s, when dozens of factors began combining to make their age-old home suddenly inhospitable. Now the only way to save the Testudines may be to enlist the support of robots, lasers, and, of course, bureaucracy.

Let’s first discuss ancient animals’ many threats, beginning with invasive plants like Asian mustard, which has started taking over the Mojave, stealing what little water it has from its native flora and providing less nutritious forage for its tortoises. Another invader called red brome grass has little spikes that injure tortoises’ mouths when they try to eat them, causing sores that can lead to infection. Nobody knows exactly how or when these weeds came to the desert, but scientists suspect they’re tied to livestock grazing operations, which brings us to another problem. Grazing animals like cattle avoid the invasives and feast or trample on the plants the tortoises need.

Red brome’s destructive wake doesn’t stop at mouth sores, unfortunately. When this grass from Spain takes over enough area, it creates vast monocultures that dry out under the summer sun and sit like a field of tinder waiting for a spark. All it takes is a lightning strike or an errant cigarette butt to turn the desert into a swirling inferno for thousands of acres.

These types of wildfires aren’t natural for the Mojave and are terrible for tortoises in all kinds of ways, says ecologist Roy Averill-Murray, the desert tortoise recovery coordinator for the U.S. Fish and Wildlife Service (FWS). The reptiles aboveground get cooked in their shells, while smoke inhalation and intense heat snuff out those that are trapped in their bunkers.

“Any tortoises that do manage to survive are left with a moonscape,” says Averill-Murray, referring to the loss of shade trees, shrubs, and food sources. Making matters worse, the invasive plants bounce back faster after a fire than the natives, so the whole ecosystem degrades even further as it resets.

Meanwhile, development of all kinds is also carving up tortoise habitat. Agriculture, energy projects, housing plans, off-road vehicles, railroads, and military exercises all make the list. The reptiles also suffer from an upper respiratory tract disease that spreads by pet tortoises released into the desert. (Desert tortoises collected before the species was listed as threatened in 1990 are able to be kept legally as pets, but each year, more than 1,000 of them are put up for adoption.) And as if that’s not enough, our landfills, dumpsters, and garbage cans fuel booming populations of ravens and coyotes, both of which turn to tortoises for food when it suits them. “We hear reports from our surveyors that it’s just really hard to find small tortoises anymore, presumably because the ravens are finding them first,” says Averill-Murray.

Some level of raven predation is natural, especially for young tortoises, which have thin, peck-able shells. But Averill-Murray says they’re now seeing ravens team up to take on adult tortoises, attacking their weak points and leaving them severely injured or dead. This is particularly concerning because older tortoises are the baby-makers.

A desert tortoise hatches

K. Kristina Drake, USGS/Flickr

“It takes a long time to grow a tortoise,” says Averill-Murray. A wild desert tortoise can live up to 80 years but doesn’t become sexually mature until about age 15. “And that’s just to start producing eggs,” he says. Another 15 or 20 years pass before a female really reaches her full reproductive potential.

The good news is that a few raven-repelling techniques are in the works, and they include laser guns and robotic tortoises. Seriously.

Ravens see green lasers as solid beams, and while the birds are known for their smarts, they don’t realize that these mile-long light sabers can’t hurt them. Ravens avoid lasered-off areas for long periods after the light show. According to Averill-Murray, the laser method was a tested on a pistachio farm, and after firing up the lasers just a few times, the birds left. How long they’ll stay away or whether they’ll eventually get used to lasers is unknown, but the results are encouraging. If ravens are willing to abandon a really dense food source like a field of nuts, getting them to vacate areas with a few scattered tortoises should be even easier.

Robo-tortoises are another alternative. These 3-D-printed decoys emit yucky-tasting chemicals when harassed by predators. The hope is that ravens, and maybe even coyotes, learn to associate tortoises with a bad flavor so they’ll leave the real-life reptiles alone. The decoys could be particularly helpful because, after deployment, they wouldn’t require much oversight. That is, no one would have to drive into the desert and turn them on, like the lasers.

While fun and great for headlines, life-saving lasers and robots aren’t ready for mass deployment quite yet. What will help tortoises on a daily basis, however, is pretty boring. In a word, bureaucracy.

Before the FWS created its Desert Tortoise Recovery Office in 2005, the species’ conservation hinged on the needs, abilities, and budgets of governments wherever the tortoises happen to crawl. I’m talking about a habitat ranging across four states and winding through numerous jurisdictions including the Bureau of Land Management, the National Park Service, various military installations, as well as state and private lands. And while each agency may have done its best to help out, a more coordinated approach was necessary.

Under Averill-Murray’s leadership, the DTRO has identified more than 40 threats to the reptiles’ continued existence, analyzed each habitat, and focused on ways to address the specific needs of each population. This is key, because whatever is killing off tortoises in Nevada might be different in California, Arizona, or Utah.

For Averill-Murray, this means a lot more time spent behind a desk and in meetings, trying to get the gears of various governments to turn in the right management directions—be they planting more native grasses, educating motorists about avoiding tortoises on the road, or making sure energy companies do their part to minimize their impacts on any tortoises near their sites. 

“Some places are doing better than others, and some are doing quite worse than others, but it’s not all doom and gloom,” he says. In fact, a range-wide monitoring program from 2004 to 2014 found that a few populations of adult tortoises were actually increasing.

Some threats, however, lie beyond the reach of the DTRO, namely climate change and the severe droughts that could come with it. No matter what, it will be a long haul for conservationists to save this species from extinction.

The tortoises seem to have the patience for it. Do we? 

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