Stretching across a piece of prairie in southwest Wyoming is the state’s first industrial solar field. It’s a small piece of the nation and world’s transition away from fossil fuels to renewable resources. It’s one part of the solution to a warming world that’s wreaking havoc with historic floods, droughts, tornadoes and wildfires. 

It’s also interrupting critical big game movements and eating up habitat, according to a new paper co-authored by long-time Wyoming big game researcher Hall Sawyer. 

“We need renewable energy, but we need to do it in a smart way,” Sawyer said. “Utility-scale solar highlights that better than anything. For big game, this is really an emerging issue because unlike the smaller-bodied mammals that can move through these perimeter fences, these larger-bodied mammals are completely blocked and can’t move through it.”

The paper, titled “Trade-offs between utility-scale solar development and ungulates on western rangelands” is the first in the country to examine and quantify the impact of solar fields on big game. It isn’t anti-solar, Sawyer is quick to say, but it does ask land managers and solar companies to think about siting and design. In the wrong place, he said, a solar field the size of some being built in states like Nevada and Arizona could add pressure to already-struggling herds of pronghorn, deer and even elk. 

A group of pronghorn on Wyoming’s public lands. Wildlife compete with other natural resource values, like oil and gas development, for use of the landscape. (Tom Koerner/USFWS)

And solar is coming quickly. The renewable source is projected to grow from 3% of the U.S. supply to 40% by 2035, according to a U.S. Department of Energy factsheet, and to 45% by 2050. The transition will cost about $210 billion, but estimates say it will save the country about $1.7 trillion in climate damages and improved air quality. 

Sawyer and his co-authors offer some solutions to that loss of habitat, including altering the fencing that encompasses each project, breaking the project up into smaller pieces, siting solar in already-disturbed areas and avoiding important migration routes.

“The goal should be to not make the same mistakes that we’ve made with siting oil and gas development,” said Jon Holst, wildlife and senior energy advisor for the Theodore Roosevelt Conservation Partnership. “The goal should be to be thoughtful about how we put these on the landscape.”

A pronghorn roadblock

As far as industrial solar fields go, Wyoming’s is pretty small at about 640 acres. It’s also not in the worst location. Sawyer lists three criteria that developers generally use when considering building a solar farm: Proximity to existing roads, proximity to existing power infrastructure and developing in an already disturbed area. 

This field met the first two — it’s right on Highway 372 and near existing transmission — but the relatively small slice it bit out of the prairie was undeveloped land. It also turned out to be critical pronghorn habitat. 

Big-game collaring data showed that 86% of migrating pronghorn moved through the area prior to the solar farm being built. About 70% of the resident pronghorn used the area. 

“As you drive through there, it’s not a pristine landscape,” Sawyer says. “This is adding to existing oil and gas development, large trona mines, highways, traffic and railroads. It’s not like this is the only thing pronghorn have to worry about, but it’s another cut in death by a thousand cuts.”

The issue is less with the solar panels themselves and more with the 6-foot-high chain-link fence surrounding the development. The National Electric Code requires security fencing around solar facilities just like it’s required around refineries or power plants. But in the sagebrush rangelands, it means more big-game habitat lost. 

A perimeter fence stands between Highway 374 and Wyoming’s first industrial solar development. The fence creates an impenetrable barrier for big game. (Hall Sawyer)

Angi Bruce, Wyoming Game and Fish Department’s deputy director, wasn’t surprised by the study’s results. Game and Fish had requested the Bureau of Land Management contract with researchers to study the impact because they feared it could turn out this way, she said. 

“It’s all about location, and when we’re putting it out in native sagebrush habitat there’s a high risk of impacting wildlife because you’re destroying that habitat,” she said. “The big game movements are a huge concern.”

While this issue may feel new to Wyoming, it’s not new across the country. 

Battles are raging from Massachusetts to California about proper siting of solar facilities, according to the Pew Charitable Trusts. As state and federal leaders try to address climate change by reducing the nation’s reliance on fossil fuels, local leaders and land advocates are asking for regulators to take a step back and be more thoughtful about where to place development. 

“With any energy development, we can find a way to work with it if proponents are willing,” Bruce said.

We can have both

Carbon-reducing solar panels can be developed while minimizing the impact on big game, Sawyer and the other authors stress. 

Developers are already working on solutions to the southwest Wyoming field to try and prevent antelope from becoming stuck between the perimeter fence and the highway like they did during a bad storm in 2019. Game and Fish is working with the current owner, Clenera, to modify the fencing and open an alleyway so animals can move between the fence and highway instead of inside the right of way, according to the agency. An email to the original owner, 174 Power Global, was not returned by press time. 

With some advance planning, solar companies can potentially separate portions of the fields to create some permeability in the facility. They could also possibly site the projects in slightly different places to avoid major migration routes or winter range, Sawyer said. 

Building in already-developed areas is also important. A solar project planned north of Casper is in an area with current industrial uses, Bruce said. Game and Fish gave few comments during the project’s approval process because little wildlife use the area right now. 

This map from the study shows year-round (2017–2019) movements of migratory pronghorn captured from the Opal herd, which migrates through the study area periodically in response to harsh winter conditions. (Screengrab/Trade-offs between utility-scale solar development and ungulates on western rangelands)

The paper also highlights the need to study, map and understand current migration and land-use patterns before development begins. 

“Solar can be constructed so quickly compared to an oil and gas field or wind farm, it’s hard to get pre-development data,” Sawyer said. “In states like Wyoming, if there are areas that are likely to have solar potential, we should preemptively monitor those areas so when these proposals come across desks and developers want to choose sites, they can proactively site those better.”

Holst with TRCP advocates for some level of federal guidelines. Wyoming recently added solar to the industrial siting process, Holst said, which will help, but most other states lack a way to formally require companies to consider big game movements. That’s a problem when some solar fields are 2,000 to 3,000 acres. 

He’s hopeful that leaders will pay attention to research like this paper and plan accordingly. 

“We’ve been through the ringer with siting oil and gas facilities with respect to big game and sage grouse in the West,” Holst says. “We know how to do this stuff and deal with development pressure, it’s just a matter of having the political will.”

The second volume of “Ungulate Migrations of the western United States” recently published, helping add to the body of science showing where animals move. 

“Climate change is a huge deal, and it needs to be,” Holst says. “But that doesn’t mean we should ignore what we know about science and how to avoid and minimize the impacts of development on the ground.”

CORRECTION: This story has been updated to correct the type of fences, perimeter, around solar facilities. -Ed.

Christine Peterson

Christine Peterson has covered science, the environment and outdoor recreation in Wyoming for more than a decade for various publications including the Casper Star-Tribune, National Geographic and Outdoor...

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  1. Why not put the solar panels on existing company groups or on tops of the mall roofs then giving the businesses or the mall owners tax credits win-win for both

  2. I travel Hwy 372 every weekend. I watched the solar panel farm being built from the beginning. The pronghorn were scared running up and down the fence line then onto the Highway. A very sad thing to see. At the time, I did not know that was a crossing for the pronghorn. My first thought was why would you build a solar farm and not study the migration route that these animals follow every year. We are seeing a decline in pronghorn, deer and elk. We are seeing less of these animals as we hunt every year. Progress can destroy a habitat for all of these animals.

  3. Christine,

    What about the tremendous number of raptors and bat’s killed by those God ughly denzions of the wind? Not only are those huge windmills killing tremendous numbers of these majestic birds, they are totally polluting our landscape visually as well as noise. And to what end other than to dramatically increase the cost of our electricity while making a few big corporations & ranchers very rich.

    We need to ask ourselves this question, “Is the attempt to prevent the “purported climate change” really worth totally ruining our natural environment?”

    FYI: I would challenge you as a news person, to talk to weather scientists, Don Day in Wyoming a place to start, to ask about historical weather and weather patterns. You might be surprised as to what you learn!

    Do you remember the dust bowl? How about the Columbia River freezing over? Or the winter of ’75 in Eastern Pennsylvania? Just to peak your curiosity.

  4. Regardless of management, mitigation and political control…wildlife will always be second. jp

  5. The map accompanying this article is not the same as the map in the study report, and gives a false impression of migratory pathways used by pronghorn. Ms. Peterson, why did you publish an incomplete map and eliminate Pronghorn 19? This amazing migrant travels north in the spring/summer, through the Little Colorado Desert (and through the soon-to-be-developed native habitat in the Normally Pressured Lance gas field) and into the headwaters of the Green River. She probably wasn’t alone. Let’s be honest about all the ways that habitat is and can be fragmented; it’s not just about industrial solar.

  6. In a perfect world, I would suggest mandating permits or at least impact statement reports through your DNR. However, here in the east, fracking permits come out of DNR and absolutely no consideration, as in zero, is given prior to the issuance of them. They give them out like candy at a parade. Money talks.

  7. Wyoming needs to promote rooftop solar, and small municipal installations, located in already utilized areas like near water treatment facilities or landfills. Industrial solar (and wind farms) are part of the picture, and need to be sited where they will do the least harm, but consider the acreage available on existing rooftops throughout the sate. Currently our net-metering law is weak, and being repeatedly challenged by the Legislature. A more dispersed grid would reduce the need for large landscape-destroying industrial installations.

  8. re any “clean” energy “farms” – If we are going to transform, we must promote BEST, not just proprietary “better” that funnels profits to just a few…our BAD HABIT must change of letting too many selfish corporations manipulate and buy our government ‘s decisions for their max profit – while creating and leaving problems for others to pay for, while they take the $ and run until stopped by someone(s) with a conscience and respect for the environment!

    Specifically here I am referring to 1) Vertical tube ROOFTOP wind power (and ROOFTOP solar) vs “farms” and 2) AIR VEHICLES running on compressed air vs proprietary polluting battery tech.
    NO ONE SEEMS TO TALK ABOUT EITHER OF THESE, and very few use these BETTER alternatives !!!???
    1) Although wind and solar farms are WAY healthier than fracking and fission and coal, we have almost UNLIMITED ACREAGE of awaiting ROOFTOPS already in existence. Rooftop solar (which has fortunately gained some public acceptance) and ROOFTOP VERTICAL TUBE WIND power avoid abuse of ever more scarce undeveloped land and offshore areas by companies happier to make their only cleanER profits in isolation from public scrutiny on their own isolated solar and wind farms.
    Unlike giant wind turbines in particular, ROOFTOP VERTICAL TUBE WIND POWER GENERATION:
    A) Usurps NO more rapidly diminishing open wild space.
    B) does NOT perennially and annually kill the same untold numbers of local raptors and bats and migrating birds (unlike a new high-rise, where bird collisions diminish to a much lower death rate after the worst initial year) (Oh… and don’t forget to apply for your Federal Eagle killing permit each year for your “windfarm”!) In fact, VERTICAL TUBE WIND POWER kills almost NO fauna.
    C) does not emit dangerous infra-sound. Despite wind industry claims of turbine “safety”, infrasound is used as a weapon, and its effects on local flora and fauna and humans are obfuscated and/or ignored by the wind farm industry and the public in general.
    D) is not a prominent eyesore in typically chosen and sited places that were, previously, especially beautiful unspoiled places on land or in bodies of water. Unfortunately, such places typically have higher winds.
    Relatively inexpensive and non-toxic FLOW BATTERY tech for homes can store all the rooftop generated power whether hooked into the grid or not.
    The energy companies will of course claim it is “inefficient” to make large amounts of energy this way on rooftops, admittedly perhaps less windy than their chosen “farm” sites, but what they really mean is that they can profit more easily from “farms” since the environmentally disruptive costs of the “farms” are basically NEVER factored in to what they must pay for, vs the supposedly “too burdensome” costs of creating and maintaining the less “convenient” (and therefore less profitable for them) network required for ubiquitous rooftop solar and vertical tube wind power generation.
    Think of all the thousands of holistically purposeful ongoing jobs such a “cleanEST” network would create.

    Also re best vs just better Please consider AIR car/bus transport running on the incredible power of compressed air in onboard tanks, which does NOT require socially disruptive and HIGHLY POLLUTING extraction at-source and polluting post-use battery tech, NO fuel trucks, NO filling stations for gas or hydrogen or whatever else, etc. All braking action and downhill motion energy runs an onboard compressor to recharge. However, the air cars do require occasional “external” running of onboard (or other) compressor to fully recharge compressed air tanks (by electricity from perhaps less desirable onboard internal combustion, or onboard electrical from cleanest battery and solar, or external source, BUT all preferably from CLEAN energy including EV vehicle recharge stations or at home). ALL exhaust is AIR. NO explosive fuel. Some air cars are already available in the EU. If we are going to switch, we and or government should intervene to DO IT RIGHT, vs profit driven proprietary electric transport and energy creating industries forcing their less than best show on us for a long time.

  9. Why do we need perimeter fences? How about surveillance cameras and motion detectors instead? Mount the solar panels high enough so wildlife or cattle can graze underneath and enjoy the shade. This along with tamper-resistant fasteners could make it harder to steal them.

    1. Or run them along side existing roads where they then serve as the transmission line.