SAN DIEGO — A surveillance drone is buzzing overhead. The booming of heavy artillery can be heard in the distance.
On the desert floor, Thelma and Louise, the grand dames of the desert tortoise population at the massive Marine base at Twentynine Palms, are blissfully munching on their breakfast of mixed fruit and vegetable slices.
At one time the two were the pets of a Marine general. But he deployed to Iraq, and there is no room in a combat rucksack for tortoises, despite their status as the state reptile of California.
Now Thelma and Louise are assigned to help base officials explain to schoolchildren the ambitious, albeit slow-moving, plan to reverse the decline of the desert tortoise on the base by hatching baby tortoises in a protected facility away from natural predators like ravens and lizards and man-made ones like tanks and Humvees.
So far, about 500 hatchlings live in the 5-acre Desert Tortoise Head-Start Facility, protected from predators by wire and netting. The program began in 2006 under a partnership between the Marine Corps and UCLA, with a budget of about $100,000 a year from the Department of Defense.
It will probably be a year or more before any of the young are released. A 4-year-old tortoise can fit in your hand, a size that makes it easy pickings for a hungry raven.
No wonder that biologists call young tortoises “walking ravioli."
“The program is going well, but it’s taking longer than we hoped," said Ken Nagy, emeritus professor in the department of ecology and evolutionary biology at UCLA, a desert tortoise expert overseeing the hatchery program. “These animals grow very slowly, they do everything very slowly."
Slow or not, the Marines are sticking with the program. In matters of war or endangered species, the Marine Corps is loath to retreat.
“If you don’t start somewhere, you’ll never get where you want," said Marie Cottrell, natural and cultural resources officer for the 600,000-acre base, formally known as the Marine Corps Air Ground Combat Center.
Tortoises in peril
Modernity has not been easy on Gopherus agassizii, the desert tortoise of California, Arizona, Nevada and Utah.
Residential development has put man and tortoise on a collision course; the use of off-road vehicles has also taken a toll; an upper respiratory disease has ripped through the tortoise population.
Still, it’s the raven that poses the greatest current threat, according to tortoise experts. The federal government in the mid-1990s declared 6.4 million acres of desert, most of it in California, as critical habitat for the tortoise, restricting all sorts of human activity.
But ravens are oblivious to federal land-use decrees. By one study, the raven population has increased tenfold in the Mojave and Sonoran deserts in recent years. Tortoise experts say that more than 90 percent of young tortoises, their innards protected only by a still-soft shell, do not reach maturity.
One of the oldest tortoises at Twentynine Palms suffered a different but equally unfortunate fate. Old Grand-Dad, who, unlike Thelma and Louise, lived outside the protected hatchery, was killed by a marauding canine.
Help from the Marines
Long ago, it was said that young Marines made sport with the tortoises, staging ad hoc tortoise races. Things have changed: Now, woe betide the grunt who molests or annoys a desert tortoise.
More than 90 percent of Marines who deployed to Iraq or Afghanistan came to Twentynine Palms for several weeks of grueling training known as Mojave Viper. And every one of them received a video lecture about the tortoise’s threatened status under the federal Endangered Species Act. Troops were warned to halt all training and notify the range master the moment a tortoise is spotted.
Marines are also ordered to make the base less hospitable to ravens by picking up food litter and making sure trash cans have lids that are “raven-proof." Anti-raven pamphlets titled “Invasion of the Tortoise Snatchers" are handed out.
Still, officials expect a census now under way on the base to show a decline in the desert tortoise population.