By Mike Koshmrl
Jackson Hole News&Guide
Via Wyoming News Exchange
JACKSON — Wyoming wants to protect a celebrated pathway for Jackson Hole pronghorn that kicked off a national discussion of big-game migrations in the American West.
The “Path of the Pronghorn,” used by a few hundred animals that are part of the Sublette Pronghorn Herd, is the first federally designated wildlife migration corridor in the United States. Tracking collars first detected the route decades ago. The Bridger-Teton National Forest first protected the corridor in 2008, but its southern reaches leading to pronghorn winter range have so far escaped recognition.
Using a dozen years’ worth of pronghorn movement data the Wyoming Game and Fish Department is now proposing to recognize the passageway from Grand Teton National Park, through the Gros Ventre and Upper Green valleys, all the way south across the sagebrush sea to near the Big Sandy River — altogether a 100-plus-mile journey for some animals.
“When I read about it I was surprised, but I smiled broadly and said to myself, ‘Yes! Small steps,’” said conservation biologist Joel Berger, who researched the pronghorn migration with Teton park biologist Steve Cain and helped convince federal authorities to protect it 11 years ago.
Since then, drilling has intensified in major Green River basin natural gas fields that overlay the pronghorn migration. Private lands that share the path have been developed.
“It’s always nice when we can get conservation on the ground rather than waiting 10 or 20 years, because we lose a lot in the interim,” Berger said. “We’ve lost a lot, but I’ll say in a positive vein it’s not too late.”
Wyoming’s proposal to protect the pronghorn migration appears to be vexing the oil and gas industry.
“If you’re not familiar with Pinedale and Sublette County, [the migration] cuts down the spine of the sixth-largest natural gas field in the country and then dumps into the eighth-largest natural gas field in the country,” Jonah Energy Director Paul Ulrich said in February at a Game and Fish meeting in Casper about migration issues.
“I’m questioning why we’re talking about a draft corridor and a migration corridor for pronghorn in two of the most intensely filled fields in the country,” Ulrich said. “At some point I’d love an answer for why we’re addressing that particular issue, when they’re traveling right down the densest development in the state of Wyoming.”
Ulrich’s employer operates the Jonah field, which overlaps a “low-use” portion of the proposed corridor. Jonah Energy last year also won the final OK from the Bureau of Land Management to drill the Normally Pressured Lance gas field, a 3,500-well development south of the Jonah field that’s also located in the low-use reaches of the corridor.
North of both those gas fields is the 198,000-acre Pinedale Anticline Natural Gas Field, which started being drilled the same year the Bridger-Teton recognized the Path of the Pronghorn’s northernmost stretches. The Anticline occupies high-, medium- and low-use areas along the BLM’s portion of Wyoming’s proposed migration path, maps show.
Game and Fish’s Pinedale Region wildlife coordinator, Brandon Scurlock, was the state employee most involved in designating the “Sublette Pronghorn Corridor.”
“It’s pretty important,” Scurlock said. “It’s the source of pronghorn for Jackson Hole.”
He collated movement data from 580 collared animals collected by Wildlife Conservation Society researchers between 2005 and 2017, selecting GPS locations from 111 of those pronghorn that traveled more than 50 miles to generate the proposed corridor. While Jackson Hole summer-sojourning pronghorn made up one cohort, there were others involved, too, he said.
“Animals that summer in the Upper Green, Bondurant and the east slope of the Wyoming Range all contributed,” Scurlock said.
The overall size of the Sublette Pronghorn Herd was last assessed at 38,000 animals, he said.
“It’s one of the biggest pronghorn herds, well anywhere,” Scurlock said.
Among Western states, Wyoming is pioneering the process of designating ungulate migrations, having developed a strategy to do so in 2016. Three wildlife passageways have already navigated the state’s designation process, including a Sublette mule deer herd migration that takes animals from the Red Desert all the way to the Hoback River Basin. Mule deer migrations in the Baggs area and Platte Valley are also designated.
A proposed Wyoming Range Mule Deer Herd migration would become the fourth route recognized, Scurlock said, and the Path of the Pronghorn the fifth.
At this point Wyoming Game and Fish is still vetting the proposed designation with the general public. Later on, a detailed “risk assessment” will be developed.
Meetings were held around western Wyoming, though no meeting has been announced in Jackson. At a Pinedale public meeting last week over 70 people came out, and naysayers were noticeably lacking.
“I think there was overwhelming support for the corridors,” Scurlock said. “Some folks asked, ‘How soon can this be done?’”
Attendees who weren’t happy, he said, largely had questions about the protections Game and Fish’s migration policy may or may not afford.
Veteran natural gas industry watchdog Linda Baker was among those people, and she told the News&Guide that she struggles to accept that the policy does not prohibit the extractive industry from leasing acreage within migration corridors. The state’s standard — which recently brought protests over the sale of thousands of acres within the Red-Desert-to-Hoback migration — is that leases are only off-limits to industry if they’re 90 percent or more within a designated corridor.
“There’s a lot of science on how migration corridors are threatened by interruptions and interferences of various kinds,” Baker said. “I think that when you look at Game and Fish’s own data you can see that our herds aren’t doing as well as they were 20 years ago, and interruptions to migration corridors are just unwarranted at this point.”
Berger’s hope is that Wyoming’s recent batch of designated migration paths is a jumping-off point for preserving wildlife passageways regionally.
“What we should be seeing is an entire Greater Yellowstone network of migration corridors,” Berger said. “Not just one here, one there.
“We should have Idaho, Montana and Wyoming all connected in this most wild part of the lower U.S.,” he said. “If the agencies could facilitate this it would be a broader good for all Americans.”