It starts with coughing and sneezing, and usually ends in death.
Over the past year, bighorn sheep in 11 herds in Montana, Nevada, Washington, Wyoming and Utah caught pneumonia. More than 1,000—or about half of the affected herds—succumbed or were culled, with Montana alone losing about 10 percent of its bighorns.
The vector? In two cases, bighorns had mingled with domestic sheep or goats; in most others, it was at least a possibility. Domestics carry microorganisms known to cause pneumonia in their wild cousins, which disease and other factors have reduced to a fraction of their historic numbers. Decades of research suggest letting the two species mix is disastrous. Still, many sheep ranchers argue that transmission isn't well enough understood to warrant drastic action.
In a study published this summer, though, Washington State University researchers demonstrated conclusively that bighorns picked up lethal pathogens from domestic sheep.
- Photo by Chad Harder
- Over the past year, Montana has lost about 10 percent of its bighorn sheep population to pneumonia. Researchers believe the main reason is lethal pathogens picked up from domestic sheep.
The findings add momentum to a recent wave of concern over the West's bighorns—one that has led federal agencies to be more proactive about separating them from domestic sheep on public land.
For four years, the Western Association of Fish and Wildlife Agencies has convened the Wild Sheep Working Group to help coordinate policy between the feds, states, NGOs and ranchers. Meanwhile, the Forest Service's Rocky Mountain and Intermountain Regions recently listed bighorns as a sensitive species, mandating extra scrutiny for projects that could affect them. Both the Forest Service and Bureau of Land Management are updating their general bighorn policies. And this July, Idaho's Payette National Forest—ground zero for the sheep debate, where several tribes and three states have a stake in wild herds—decided to phase out domestic sheep grazing on nearly 70,000 acres, or about 70 percent of its allotments, over the next three years.
Starting in 2005, appeals and litigation forced Payette officials to figure out a better way to protect the two bighorn populations that range within forest boundaries—one reintroduced, and the other a native herd that has declined 47 percent since 1981. Using 54,000 telemetry points tracking bighorn movements, forest planners worked with scientists from the University of California, Davis to determine home ranges and how far individuals roamed. They combined that information with domestic sheep allotments to develop computer models that showed the risk of contact between the two species. The analysis, considered the most comprehensive to date, led Forest Supervisor Suzanne Raineville to reserve an extra 346,696 acres for bighorns.
"That's what our laws tell us to do," says Forest Planner Pattie Soucek, the lead on the project. "When you have permitted activities on public lands, it's not supposed to be to the detriment of native species."
So far, eight appeals have been filed. Some bighorn advocates, including tribes, environmental groups and the states of Oregon and Washington, object that grazing cuts won't be implemented immediately. In her appeal, rancher Margaret Soulen Hinson says she'll be forced to sell 25 percent of her sheep, possibly sinking her operation. A coalition of sheep industry groups contends that the plan may harm the industry nationwide. Officials will meet with appellants to try to resolve such concerns in December.
The Payette plan is a more aggressive approach than the feds have taken in the past. States and groups like the Wild Sheep Foundation have generally driven progress on separation, working with producers to shuffle or retire grazing allotments, says Kevin Hurley, bighorn sheep coordinator for the Western Association of Fish and Wildlife Agencies. The Forest Service, meanwhile, has cooperated with such efforts and evaluated vacant allotments to see if they should be closed, says Melanie Woolever, director of the agency's Full Curl program, which works on bighorn issues. The agency has also developed a GIS map that overlays bighorn range with domestic sheep grazing allotments across the West to aid such projects.
But in Idaho, efforts at collaboration failed to bear fruit. That may have made top-down action on the Payette inevitable, say Hurley and Wild Sheep Foundation president and CEO Gray Thornton, and created a model for protecting bighorns in other contentious spots.
Indeed, the BLM's Cottonwood field office and the Nez Perce National Forest, which share bighorn herds with the Payette, are considering the forest's analysis as they examine their own grazing allotments. The Forest Service also plans to adapt the analysis so that land managers elsewhere can use it, Woolever says.
Agency concern over separating the two species is hardly new, she notes, but increased public scrutiny has brought the issue to the fore. On the Payette plan, for example, 90 percent of the 29,000 public comments received asked the agency not to accept any risk of disease transmission to bighorns. Combine that attitude with new research, Woolever says, "and you start having changes in agency direction."This story originally appeared in the Nov. 22 issue of High Country News (www.hcn.org).