Wyoming’s bighorn sheep are pressed by skiers
Over the past century, the Teton sheep have survived a multitude of serious threats, including hunting pressure from humans. The same awe-inspiring rock climbing skills that keep bighorns clear from grizzlies, eagles, and wolves also helped them avoid extirpation by hunters. The regulation of hunting on National Forest and National Park land also benefited the animals.
Livestock grazing in the early 1900s left the Tetons overgrazed and prone to erosion, to such a degree that dust clouds made by domestic sheep could be seen for miles, Whitfield said. The wild sheep moved more freely then, and found other forage.
In the early 2000s, the Bridger-Teton National Forest and the Wyoming Chapter of the Wild Sheep Foundation took action to eliminate the threat of disease spreading from domestic sheep into the Teton sheep herd. They did so by buying up domestic sheep grazing allotments on the west side of the Tetons from willing sellers. Many of the Idaho-based sheep ranchers stayed in business, moving their grazing allotments farther west to the Big Hole Mountains.
This opened up additional mid-elevation summer range for the Teton bighorn herd. However, the herd has slowly moved into new habitat because of their lifelong loyalty to the home ranges they were weaned on. The Game & Fish considered transplanting bighorns from the Jackson/Gros Ventre herd onto the newly opened range in the early 2000s, but decided against it when they learned the source herd was in the midst of an epidemic die-off, Kilpatrick said.
At present the bighorns’ only major threats are avalanches, and winter die-offs through disturbance, exposure, or starvation. In the mid 2000s biologists from the Game & Fish, Grand Teton National Park, and the Bridger Teton National Forest wanted to know how backcountry recreation affected the sheep. That brought about Courtemanch’s in-depth study of sheep winter range, seasonal movements, and a comparison with backcountry ski routes.
Starting in the late 1980s, Grand Teton National Park staff closed a ski route that disturbed bighorn sheep winter range. A subsequent Very High Frequency (VHF) radio collar study in the mid-1990s by GTNP biologists Steve Cain and Mason Reed led to additional seasonal closures of ski routes in the national park.
While the closures on Static Peak and Prospectors Mountain frustrated some local skiers at first, most have now accepted them because there are so many other places to ski. GTNP public relations officer Jackie Skaggs says those who break the closures usually don’t know they exist, or don’t know where they are in relation to the closure.
The closed areas aren’t marked on the ground, but skiers learn about them through a public relations campaign called "don’t poach the powder," with maps posted on websites for the Jackson Hole Conservation Alliance and the Teton Avalanche Center. The park occasionally investigates violations uncovered by observing ski tracks on closed faces, or through social media postings of skiers’ exploits. Skiing in a closure is punishable by a fine of up to $5,000, with a mandatory court appearance.
Jackson resident Reed Finlay has skied mountains on all sides of Jackson Hole since the early 1990s. Now a ski patroller with the Jackson Hole Mountain Resort, he says most skiers recognize the importance of the closures and have a respect for the sheep.
GTNP biologist Sarah Dewey, who worked closely with Courtemanch during the study, said the research confirms that existing closures have largely succeeded in protecting sheep habitat in Grand Teton National Park. The study identified further areas of the Tetons that sheep could be using in winter, but are avoiding.
Courtemanch collected data on skier routes by asking some 800 backcountry users to voluntarily wear a GPS device for the day. Many of the skiers who enter sheep winter range originate at just a few popular trailheads and at Jackson Hole Mountain Resort. When she mapped the skier data with the sheep data, the results suggested disturbance from skiers causes sheep to avoid a significant amount of otherwise ideal winter range.
It’s possible further winter closures on Bridger Teton National Forest could help take pressure off the sheep, though managers haven’t considered any yet. Kilpatrick pointed to Jensen Canyon as one area of possible discussion, where restricting travel to a single corridor could allow skiers to unobtrusively pass through sheep winter range.
Importantly, any future closures would not affect the vast majority of skiers, while leaving many other places to ski in the Tetons from December through March. The closed areas would remain open to late spring skiing in April and May.
"We have disease taken care of," Kilpatrick said. "The next topic is habitat. Let’s start with working with the backcountry users, and provide a little more habitat by restricting use." In addition, Kilpatrick said managers could use wild and prescribed fire to improve low elevation summer habitat on the west side of the Tetons.
Further discussion of management of the Teton sheep will wait until this fall, to give time for Courtemanch’s study to make it through the academic peer-review process. At that point the inter-agency Bighorn Sheep Working Group will meet to discuss the study and any potential policy changes on National Forest land. Any further closures would be considered in a public comment process, said Dale Dieter, district ranger with the Bridger-Teton National Forest.
While it remains to be seen what actions will be taken to preserve the sheep, it’s clear no one wants to see the herd decline or disappear.