There is no dispute that all avenues of solar development need to be explored to supply clean energy to our ever expanding human population.

The Gemini solar & battery storage project in northeastern Clark County is but one, but an important member of the industrial scale group. That’s why, as lead tortoise biologist for Gemini, I wanted to respond to your story in last week’s story, “The Tortoise vs. the Bulldozer.”

That article quoted liberally from Kevin Emmerich, director of Basin and Range Watch. While I applaud Mr. Emmerich’s conservation ethics, some of the statements attributed to him are erroneous. Perhaps most egregious is his statement that tortoises migrate, and that the Gemini project encompasses a crucial migration corridor for species preservation.

Tortoises do not migrate.  That is a term reserved for animals like ungulates that move from wintering to summer grounds and back, or birds, that migrate long distances to their breeding grounds, then return to the wintering areas. By contrast, tortoises have small home ranges, generally less than a square mile, and remain there year-round.

What is important for species persistence, however, is connectivity, especially between important core populations in federally designated critical habitat. The Gemini site is neither in nor near critical habitat, but it is inside a mathematically modeled, broad connectivity corridor extending from Las Vegas to Mesquite.

As with most models, site-specific factors must be considered and the U.S. Fish and Wildlife Service did this at Gemini. In their Biological Opinion for Gemini, they evaluated connectivity, concluding that “opportunities for desert tortoise connectivity would be modified by construction of the Project, but not significantly.”

A desert tortoise in the Mojave Desert of Southern Nevada.

Limiting loss of habitat

We are undertaking an extensive effort to minimize the obvious loss of habitat that will occur at the Gemini site. The project is mowing, rather than completely blading 65% of the site, for example. Without doubt, the site will be altered by maintenance roads and fields of panels.  That said, the mowing is required to be only to 18-24” above the ground surface.

The dominant plant species on the site, burrobush, is shorter, so will be less affected, although it will most certainly be crushed in some locations during the construction process. Fortunately, this is also a colonizing species and will bounce back quickly.

Other less abundant, taller species will be affected, and some will never re-grow. But the hope is that the altered habitat can still support many desert species, including desert tortoises.  If tortoises can still thrive in the altered and surrounding unaltered landscape, then this will be a vast improvement over the razed landscapes of nearly all other industrial scale solar projects.

Future management decisions

The ISEGS project at Primm was the first desert solar project to mow, rather than blade, and the habitat has re-grown substantially; it was the inspiration for mowing at Gemini. Unlike Gemini, tortoises were not permitted to re-occupy that site, but the Bureau of Land Management, Fish and Wildlife Service, and I feel strongly that tortoises will re-occupy the Gemini site.

Our investigations will center on how tortoises re-use the site, as well as on vegetation re-growth and introductions of non-native species.  Several detailed scientific studies have been developed and peer-reviewed to examine these factors. While research can never replace lost or highly disturbed habitat, it can provide critical insights into future management decisions, including continued green-energy development in the southwestern deserts.

Alice Karl has two advanced degrees on desert tortoises and 44 years studying tortoises, rare plants and ecology in the southwestern deserts and Mexico.  She has co-authored several papers, including describing a new species of tortoise in Mexico, and has been the principal investigator on many research projects.  She has developed and/or contributed to many of the current protocols used for desert tortoises.  She has led several translocation projects, including the largest translocation project to date.

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  1. Just to be clear, I did not use the word “migrate” and am not in quotations saying it.

    Alice Karl’s response is interesting, but not all of the details were carefully thought out.

  2. As a former Mojave desert tortoise consulting field biologist working long days on the ground on industrial development projects to try to reduce harm to this federally protected species, I carried the shovel to dig up the tortoises from their underground burrows on desert lands. I was the “blue collar” tortoise biologist.

    Dr. Karl “hopes” that this heavily altered and industrialized energy landscape will support native desert plants and tortoises in the future. The fact is this is still a giant experiment on relatively intact, healthy habitat that should be avoided in order to stave off the extinction crisis and conserve biodiversity.

    I knew tortoises didn’t need artificial shade structures such as solar panels built into desert ecosystems, because they are fantastic diggers—they have long claws on their forelimbs which have served them well to find shelter in the arid environments of the Southwest for thousands of years. They can dig a perfect burrow with these shovel-claws expertly down 10-15 feet, with curving tunnels, cool room-chambers, and special places to lay their eggs out of the desert heat. Ask me, I’ve dug up plenty of these burrows to translocate the tortoises “out of harms’ way.”

    Desert tortoises are very well-adapted to these dry landscapes, and related fossil tortoises are known from California since the Miocene (23 million to 5.3 million years ago). Tortoises have adapted to increasing dryness over the millions of years as the grassy savannas and woodlands gradually became more hostile deserts. The ability of tortoises to burrow underground allowed them to escape the aridity and decreasing rainfall of climate change during these millions of years. They do not need us humans to survive in the desert with artificial shade structures or solar panels.

    Yet during the current extreme drought, we may see a higher mortality rate as the tortoises are dug up out of their sheltering burrows and removed.

    Despite all these attempts over the years at “mitigation”—such as mowing the desert to allow industrial energy projects to be built, the Mojave tortoise has been declining across its range like a rock thrown off a cliff. According to US Fish and Wildlife Service surveys, rangewide in Critical Habitat Units and Tortoise Conservation Areas the Mojave desert tortoise declined 32% from 2004 to 2014. In the East Mojave Recovery Unit, tortoises plunged 67% during this time.

    Mowing natural vegetation is just the latest attempt to pretend we are helping to recover this severely declining species, while continuing to destroy and degrade large swaths of its habitat. Much of the natural vegetation at the site of the Gemini Solar Project is tall creosote bush, sometimes 5-6 feet high. Tall creosote is codominant with low bursage on the site, in my observations visiting the valley along the route to the Muddy Mountains Wilderness Area and Valley of Firer State Park. Much taller catclaw acacias and desert willows along washes will be severely cut down, and we wonder how they will recover.

    Culturally important native bunchgrasses to indigenous tribes, such as Rice grass and Big galleta grass, will be driven over for many months by heavy machinery during construction of this energy project, and no study has told us what the results will be to these plant species.

    If we leave these native deserts intact, the tortoises will be better off. The culturally significant native plants will be left intact. And our public lands will not be fenced in and recreational opportunities excluded on over 7,000 acres of pristine land.

    Basin and Range Watch has participated in symposia held by the Desert Tortoise Council annually since 2000, and we know full well that the 11-square-mile Gemini Solar Project has been poorly sited right across a high-priority genetic linkage corridor. Mr. Emmerich was not quoted as saying “migration corridor,” but whatever you call it, this massive utility-scale solar project will contribute towards hindering connectivity between critical habitat units. And more large-scale solar projects are in the planning stages.

    These solar panels should be built onto carports, on top of buildings and warehouses, in empty lots, on rooftops in the urban built environment, and already disturbed lands, in order to help stop the negative effects of climate change.

    I worked with Dr. Karl briefly about 15 years ago on a large-scale industrial development and tortoise translocation project in the West Mojave Desert of California. We have very different worldviews on what tortoise conservation should look like.

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