Stubborn does not come close to describing the desert tortoise, a species that did its evolving more than 220 million years ago and has since remained resolutely prehistoric.

How this creature the size of a shoe box became the single-biggest obstacle to industrial-scale solar development in the Mojave Desert is turning into a true story of the survival of the fittest.

At the $2.2 billion BrightSource Energy solar farm in the Ivanpah Valley, the tortoise brought construction to a standstill for three months when excavation work found far more animals than biologists expected.

BrightSource has spent $56 million so far to protect and relocate the tortoises, but even at that price the work has met with unforeseen calamity: animals crushed under vehicle tires, army ants attacking hatchlings in a makeshift nursery and one small tortoise carried off by an eagle, its embedded microchip pinging faintly as it receded.

History has shown the tortoise to be a stubborn survivor, withstanding upheavals that caused the grand dinosaur extinction and ice ages that wiped out most living creatures. But unless recovery efforts begin to gain traction, this threatened species could become collateral damage in the war against fossil fuels.

Costly conservation efforts by state and federal agencies and solar companies have created a mishmash of strategies that one scientist says amounts to a “grand science experiment,” said Jeff Lovich, who studies the impact of renewable energy projects on desert tortoises for the U.S. Geological Survey.

“One could argue that they are nature’s greatest success story,” Lovich said. “Yet over half the world’s turtles are in dire need of help. The common denominator is humans. They may not survive us.”

An ideal site

Long before construction began, BrightSource was warned that the site was thick with tortoises, more so than any of the other dozen solar farms planned for that part of the Mojave.

But BrightSource wanted the site because it is ideal for generating solar power. So the company negotiated with state and federal agencies to hash out meticulously detailed protocols for collecting and relocating tortoises.

The company made its first concession to the tortoise during planning, giving up about 10 percent of its expected power output in a redesign that reduced the project footprint by 12 percent and the number of 460-foot-tall “power towers” from seven to three.

BrightSource also agreed to install 50 miles of intricate fencing, at a cost of up to $50,000 per mile, designed to prevent relocated tortoises from climbing or burrowing back into harm’s way.

The first survey of tortoises at the site found only 16. Based on biological calculations, the U.S. Fish and Wildlife Service issued BrightSource a permit to move a maximum 38 adults, and allowed a total of three accidental deaths per year during three years of construction. Any more in either category and the entire project would be shut down.

The pressure boiled over after company biologists discovered an adult female tortoise with its carapace crushed in October 2010, during a media tour of the site. Biologists concluded that a vehicle had struck the animal and ordered it euthanized.

A flurry of e-mails ensued. Steve DeYoung, then a BrightSource vice president, wrote to a federal biologist: “How in God’s name could anyone blame us? It is completely unconscionable that we would be blamed for this.”

Ultimately, the death was not attributed to the project. But other mishaps occurred: a juvenile had his right forelimb gnawed by rodent, a tortoise died of heat distress after being caught in the black plastic erosion fencing. And as tortoise numbers rose, costs went up.

BrightSource, which was paying to have as many as 100 biologists to be on the site at one time, began seeing red. The company warned that tortoise mitigation was jeopardizing Ivanpah’s viability. In an e-mail to a BLM official, DeYoung complained that tortoise-related costs could reach $40 million. “This truly could kill the project,” he wrote.

BrightSource lawyer Jeffrey D. Harris wrote to the California Energy Commission to suggest that if the Ivanpah crashed because of tortoises, the state’s renewable energy goals would meet the same fate.

By February 2011, all parties realized that the site contained more tortoises than allowed under the permit. Two months later, state and federal agencies ordered construction suspended until a new biological assessment could be completed.

At Ivanpah today, 166 adult and juvenile tortoises have been collected and moved to a nine-acre holding facility. The objective is to release them into the “wild,” on the other side of the fence from the solar facility.

Tough survivors

Tortoise relocation is a formidable issue. Moved animals nearly always attempt to plod home, piloted by an uncanny sense of direction.

To date, only one desert tortoise has been relocated at Ivanpah.

Last October, a tagged female, BS-71, had been in a holding pen for four months and wasn’t adapting. She endlessly paced her enclosure. Over and over the animal attempted to climb the wire mesh, gaining some height then usually ending up flipping on her back.

Unable to bear the sight of the tortoise’s apparent distress any longer, BrightSource lead biologist Mercy Vaughn sought permission to release the female to the wild. The request has since been dubbed the “Mercy Rule.”

After gaining approval from the U.S. Fish and Wildlife Service, filling out paperwork, providing medical testing — a tortoise under stress is more susceptible to disease — Vaughn was finally cleared to free the homesick tortoise.

The animal was placed in a bin and carried deep into the desert. While a dozen people looked on, some filming the event, the tortoise was gently placed at the entrance of a burrow. She hesitated for a moment then shuffled down into the gloom.

Moments later BS-71 re-emerged, blinked and began munching grass.

— Los Angeles Times