Ecologist Joel Berger wasn’t pleased when he learned his research had been cited as evidence — inaccurately, he says — that the famous Path of the Pronghorn migration route ends well short of Jonah Energy’s Normally Pressured Lance gas field. 

The contention came from state and federal attorneys during oral arguments last week in the 10th Circuit Court of Appeals, where environmental groups are challenging the NPL field. They argue the Bureau of Land Management didn’t properly account for impacts to migratory pronghorn and the world’s largest-known sage grouse winter concentration area

Defending the BLM’s decision from a Denver courtroom, Wyoming’s senior assistant attorney general, Travis Jordan, said studies from Berger and former colleague Renee Seidler “indicate that the Path of the Pronghorn terminates 30 miles north of the project area.”

Without naming the researchers, U.S. Department of Justice Attorney Sommer Engels made a similar claim during oral arguments Wednesday. 

“Ultimately, the Path of the Pronghorn, which is discussed in petitioner’s briefs, occurs well outside of the project area,” she told appellate judges Nancy Moritz, Timothy Tymkovich and Veronica Rossman.

Berger, a senior scientist with the Wildlife Conservation Society, charged the state and federal government’s counsel of “doing a deliberate mislead” because, he said, “we know that migration is continuous and the animals continue.

“There are semantics and there’s biological reality,” Berger told WyoFile. “The semantics are making an argument about where the legal end of the path is. But we know that … the animals that use the Path of the Pronghorn migrate far to the south of the NPL gas field.” 

Jordan, the state’s attorney, didn’t respond to a request for comment. Neither did the U.S. Department of Justice regarding an email request to interview Engels.

Presumably, the attorneys were referring to what could be considered the legal end of the officially designated pronghorn migration route — which is well to the north of the biological end. 

The famous Path of the Pronghorn migration, pictured, is typically completed by early June. It’s unclear how many animals survived the winter of 2022-’23 to make the journey. (U.S. Geological Survey)

Scientists have mapped the complete route the animals travel each year, and it extends well beyond what’s formally designated. Animals in the Sublette Herd seasonally travel as far as 220 miles one way, according to the U.S. Geological Survey. Yet only one agency has officially recognized the path — and it only recognizes the portion that traverses land it manages. The Bridger-Teton National Forest designated the route’s northern 43 miles via a protective forest plan amendment adopted 15 years ago. 

Considerable efforts to designate the more southerly reaches of the Path of the Pronghorn, which cuts through the Green River basin’s gasfield country, have failed or stalled. But if official designations were granted, wildlife advocates say, Wyoming could more effectively protect the critical routes. 

Years of effort

At the time of the U.S. Forest Service’s designation, “the BLM refused to participate,” Berger once told the Jackson Hole News&Guide, attributing the agency’s lack of participation to “politics.”

More recently, political pressure has stymied the state of Wyoming’s attempts to protect the migration route used by animals that summer in and around Grand Teton National Park. 

The Sublette Pronghorn Herd’s migration, which includes the Path of the Pronghorn, was next in line to be designated as a Wyoming Game and Fish Department-recognized route in 2019. A coalition of industry groups, however, protested and effectively halted the process. In the aftermath, Gov. Mark Gordon created an all-new migration corridor designation process. That was more than three years ago, and the Path of the Pronghorn has remained on deck in the designation queue

Meanwhile, litigation over the NPL gas field, once valued at $17 billion, remains unresolved. Citing sage grouse- and pronghorn-centric concerns, the Center for Biological Diversity, Western Watersheds Project and Upper Green River Alliance first brought the lawsuit in 2020, but U.S. District Judge Scott Skavdahl ruled against the three conservation groups last year. Quoting precedent, he wrote that environmental law “merely prohibits uninformed, rather than unwise decision making.”

The environmental groups appealed the decision, which led Jordan, Engels and Jonah Energy counsel Kathleen Schroder to Denver last week to exchange oral arguments with Center for Biological Diversity senior attorney Wendy Park.

A group of animals that belong to the Sublette Pronghorn Herd tread in the sagebrush below that Wyoming Range in May 2023. (Mark Gocke/Wyoming Game and Fish Department)

In those arguments, the Path of the Pronghorn took center stage. 

“Did [the BLM] consider the Teton pronghorn — the Path of the Pronghorn — as part of the evaluation, or did they completely disregard potential impacts on that herd?” appellate judge Timothy Tymkovich asked Jordan, with Wyoming. 

In its environmental impact statement and decision, Jordan said, the BLM “very candidly” said there would be impacts to migration, including the loss of migration. The agency’s analysis was of the larger Sublette Herd, he said. 

During her arguments, Park said the EIS devoted only three sentences to Jackson Hole’s migratory pronghorn. 

“It was just so general that there was no indication in there as to whether the Grand Teton pronghorn would survive or not,” she said, “and whether that Path of the Pronghorn would continue.” 

In 2018, BLM officials told the Jackson Hole News&Guide that impacts to pronghorn migration were scant in the planning documents because the corridor hadn’t been designated. 

“It would help us out if the [Wyoming] Game and Fish were to formally designate something in there,” former BLM Pinedale Field Office Manager Caleb Hiner said at the time. In lieu of codified protections, he said, the agency would “micro-site” during the application-to-drill process to diminish impacts.

Jonah Energy’s densely drilled Jonah Field, pictured here aerially via Google Earth, is located just to the north of the Normally Pressured Lance field, subject of a legal dispute. (Google)

Jonah Energy has contested designating the Sublette Pronghorn Herd’s migration route, which cuts through two more mature gas fields — the Anticline and Jonah fields — before spilling into the NPL field. The company’s vice president of public affairs, Paul Ulrich, did not respond to WyoFile’s request for comment.

In 2019, Ulrich expressed incredulity about the prospect of a state designation for the Path of the Pronghorn. 

“I’m questioning why we’re talking about a … migration corridor for pronghorn in two of the most intensely filled fields in the country,” Ulrich said at a Wyoming Game and Fish meeting that year.

A blow from winter

Amid the delayed designation, Wyoming Game and Fish Department officials have been trying to more thoroughly track and map the Sublette Herd’s movements. 

The carcasses of 16 pronghorn are clustered on a hill overlooking Highway 191 south of Boulder in May 2023. The large concentrations of dead animals are a good indication that mycoplasma bovis, which causes respiratory infection, struck the herd. (Mike Koshmrl/WyoFile)

Scientists were tracking 93 GPS-collared pronghorn in the herd at the onset of winter, which walloped the herd. Some 75% perished, including all three Teton Park migrants, leaving the Path of the Pronghorn on shaky ground. At least a few of the farthest-traveling animals remain: Jackson Hole photographer Tim Mayo reported seeing four animals in northern Grand Teton Park on Monday morning. 

The Wildlife Conservation Society’s Berger, who’s also the university chair of wildlife conservation at Colorado State University, described the winter of 2022-’23 as a “catastrophic mortality event” and a reminder of what happens when animals don’t have adequate food — in this case from an unusual inverted, persistent snowpack.

“When animals have to deal with all the pressures, all the disturbance and the loss of habitat, we know what the consequences are,” he said. “Their immune systems are compromised. And they have a higher probability of death, as we have just seen.” 

Several pronghorn forage in the Elk Ranch Flats area of Grand Teton National Park on Monday morning. The Normally Pressured Lance gas field’s impacts to the migration path of the herd, recently decimated by the harsh winter, is the subject of a legal dispute. (Tim Mayo)

Other, longer-lasting forms of pronghorn habitat loss are on display in the Green River basin. Research published in 2019 led by Western Ecosystems Technology research biologist Hall Sawyer found that Sublette Herd antelope are avoiding and even abandoning the Anticline gas field, dispelling the notion that Antilocapra americana adapts well to industrial activity. Industry attempted to partner with biologists to conserve Anticline pronghorn, but the collaborative effort ended in ruin after gas companies tried to massage data and alter reports, according to a Journal of Environmental Management study

Seidler, the other scientist whose study Jordan, the state attorney, cited during oral arguments, also criticized how her research was presented as evidence that the Path of the Pronghorn ends before the NPL gas field. 

“That’s a strange argument to put out there in the public eye,” she told WyoFile. “I think it’s pretty well known that these animals at least get fully onto the gas field in the winter, if not further south.”

‘Red flags and warnings’

Now the executive director for the Jackson Hole Wildlife Foundation, Seidler specifically examined how pronghorn used the then-proposed NPL project area during her time at the Wildlife Conservation Society. Publishing the results in the journal of Conservation Biology, she illustrated how pronghorn were using the NPL while simultaneously avoiding the drilled-out Anticline gas field and especially densely drilled Jonah field.

A map of the Sublette Pronghorn Herd’s migration published by the U.S. Geological Survey in May 2022 illustrates dozens of animals traveling through the landscape where the NPL field was approved. 

“Eight years ago, we were giving red flags and warnings,” Seidler said. “We said, ‘Hey, if you’re going to develop this NPL [field], you better do it in a way that works for the wildlife or you’re going to be blocking major migration routes.” 

A map included in Renee Seidler’s 2014 study, “Identifying impediments to long-distance mammal migrations,” shows pronghorn use of the Anticline, Jonah and NPL gas fields. (Journal of Conservation Biology)

Erik Molvar, who directs one of the plaintiffs, Western Watersheds Project, described the state and federal attorney’s remarks about the NPL field and Path of the Pronghorn being apart as a “fictional argument.” 

“Since the Wyoming Game and Fish Department is responsible for managing the pronghorn that migrate along the Path of the Pronghorn,” he said, “you would think that the state of Wyoming ought to know where that migration route lies, and shouldn’t be misrepresenting it in court.” 

Molvar had no predictions about which way the appellate court would rule, but remarked that he believes the stakes are clear. 

“I think this is the big chance for the courts to reverse what is likely to be a death blow to the Path of the Pronghorn migration,” he said. 

Berger, meanwhile, said that his frustrations fall on state of Wyoming officials. It’s their delays, he said, that have clouded the picture and created ambiguity about the landscapes the Sublette Pronghorn Herd depends on to migrate. 

“Mark Gordon and Wyoming Game and Fish’s leadership should be ashamed of themselves,” Berger said. “Not the biologists. People are being suppressed within the organization. They don’t have the freedom to speak.” 

“Mark Gordon and Wyoming Game and Fish’s leadership should be ashamed of themselves.”

Joel berger

A Gordon spokesman was unable to be reached before press time. 

The governor listened to calls to designate the Path of the Pronghorn at a Pinedale meeting about the severe winter for wildlife.

“Our pronghorn cannot wait another minute,” Upper Green River Alliance Director Linda Baker told Gordon. “Please do it now.” 

The governor offered his thoughts in response. He called for a “durable” solution that transcends political swings and changes in federal land management policy. 

“Drawing a line on a map is not going to fix that,” Gordon said. 

Mark Gordon applauds Secretary of the Interior Sally Jewell at a ceremony in 2014 during which his ranch was recognized for undertaking voluntary sage grouse conservation measures. The government officials gathered at Trapper’s Point, a bottleneck in the Path of the Pronghorn migration path. (Angus M. Thuermer Jr./WyoFile)

Instead, he said, a “committed” coalition of private landowners, local agencies and the public is needed to make the “migration corridor work.” 

“That’s what’s going to be durable for generations,” Gordon said, “and that’s what we need to have.”

In 2020 Gordon issued a gubernatorial executive order establishing the state’s approach to designating and protecting migration corridors. It’s state policy, not federal, though federal officials can heed its guidelines about what occurs in migration corridors in their land management decisions. The document states that, “Wherever possible, development, infrastructure and use should occur outside of designated corridors.” 

Under the policy, the governor of Wyoming ultimately calls the shots.

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Mike Koshmrl

Mike Koshmrl reports from Jackson on Wyoming's wildlife and natural resources. Prior to joining WyoFile, he spent nearly a decade covering the Greater Yellowstone Ecosystem’s wild places and creatures...

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  1. I encourage all Wyoming citizens, as well as those Americans who cherish public lands, to write to Governor Gordon, and to the BLM to express your concerns over pronghorn management. If they have no place to weather adverse winter conditions, they will perish. Remember what happened after the hard winter of 1992? Mule deer and pronghorn have not even recovered to those numbers. Only your comments will make a difference- and your future votes.

  2. Governor Gordon says: “a “committed” coalition of private landowners, local agencies and the public is needed to make the “migration corridor work.”
    i think we’re doing pretty well on that. what we’re waiting and waiting on is governor gordon to designate the well-researched and documented migration route used by pronghorn.

  3. After the coyote, field mouse, and prairie dog, the absolute least threatened species is the antelope. Their resilience to thrive among energy sites and on grazing and agricultural land is remarkable. They even forage unthreatened among subdivisions in any town in Wyoming. The idea that the species or even their genetic diversity is threatened, even after such a tough winter is preposterous. Wildlife “corridors” are a long-used tool used by globalist environmental extremists to gain power over people and legitimate economic needs. These proponents prey on good people who believe their rhetoric to gain consensus and then destroy as many working people’s livelihoods as they can. Proponents are indifferent to the energy and food needs of a nation that is struggling for both. Wake up people and see the big picture.

    1. So perhaps the solution to declining antelope populations is to develop MORE energy fields and subdivisions?

    2. There does have to be some balance.. No the Pronghorn are not the least threatened and are subject to many stresses thus diseases. Right now the damage to a number of herds is pretty significant. The migration routes are critical to the well being of these animals as are many others. The the folks that don’t follow the science and the protections that have been put in place quit believing our wildlife magically survives. I we still have these populations because of good wildlife biologists and managers that are following the science.

  4. The pronghorn is one ancient species still on the land that makes Wyoming the unique state that it is. It would be a shame and a sad commentary if everything that could be done would not be done to keep pronghorns on the lands of Wyoming. They and all species must have habitat and migration routes (which we can track and identify) or they will decline and possibly reach a point where they cannot withstand the pressures on them.

  5. Unfortunately, Governor Gordon has and likely will continue to bow to the shorterm interests of the oil, gas and coal industries over all our other valuable irreplacable public interests – like our wildlife, clean water and clear air. It is pathetic that the state of Wyoming continues to allow the fossil fuel industries to run this state over and above our unique and valuable natural resources. Thanks to the Berger and the public interest organizations for pushing for all the necessary protections.

  6. The human species condemned itself to extinction from the time it evolved. Its memorial will be a tattered banner with a single phrase on it: “Unlimited Growth…Forever!”


  7. thank you for this important story, and shame on us for not protecting these beautiful creatures. They deserve better.

  8. Back in the day, when I was a wildlife student at UW, the WGFD was untouchable politically, though the Wyoming Legislature tried every year to wrangle and threaten them. Biologists were able to do their jobs & do it well. It saddens me that Wyoming GOP has finally succeeded in neutering WGFD & its proud biologists. The Jonah Field & Pinedale Anticline have long been a beacon for the disruptions to important historic ungulate migration corridors. Now, the NPL will just be the death sentence as these undulated vsn only stand so much human impact while also combatting climate and habitat loss. Sage grouse …well, we all know what’s been happening there. BLM has also long- relied on third-party environmental consultants for NEPA analyses, and the overwhelming majority are just doing the oil & gas industry’s bidding because they are not only being paid by the companies, but as the economics of being a viable “environmental” consulting company becomes harder, if your company doesn’t come through, then there’s always another company desperately waiting in the wings to take that business. Objectivity is just a word. One last thing, this article could have packed a bit more punch had it noted that only is Dr. Joel Berger affiliated with WCS & chair of Wildlife program at CSU, but that he has for four decades been one of the preeminent large mammal research scientists in the world. His research in the field spans from Alaska, to the Great Basin, Africa, and Mongolia. That fed and state officials are misinterpreting and being disingenuous about his and his grad students’ research is an understatement.

  9. The most profound quote in the article is: “Under the policy (the executive order), the governor of Wyoming ultimately calls the shots.” I agree, the buck stops at the governor’s desk. He can move this forward IF HE wants to. The public should inundate his office with demands to do so!