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United States Department of Agriculture

Agricultural Research Service

Sheep at Home on the Wild Summer Range

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Sheep at Home on the Wild Summer Range

Imagine walking along the Continental Divide National Scenic Trail, a route that draws a 3,100-mile line atop mountain ranges from Canada to Mexico.

In July, at 8,000 feet, you look to one side and see an array of wildflowers and Douglas-Fir trees blanketing the peaks and valleys of the Centennial Mountains. Your left foot is in Montana, your right in Idaho. Around the bend you might see a surprising group of animals—not elk or deer, which also roam the area—but a band of 1,000 ewes and their lambs.

You've entered the summer range of the U.S. Sheep Experiment Station. It is operated by USDA's Agricultural Research Service, with support from the University of Idaho.

The purpose of the range: to mimic U.S. range sheep operations. Federal research in genetics and range management helps ranchers produce high-quality food and fiber at an affordable price to consumers, while managing natural resources for sustained use.

Since 1922, ARS sheep have spent their summers grazing on Idaho fescue, cinquefoil, antelope bitter-brush, and other grasses, forbs, and shrubs in the Centennials. Private ranchers had used—and in some cases overgrazed—the same land around the turn of the century, before regulation of grazing on open range in the West.

In September each year, herders trail the sheep 40 miles, back to the valleys where they will feed on lower elevation rangelands during the fall.

Such long-distance migrations are typical of range sheep operations in the West. Seventy-five percent of the U.S. sheep industry relies on grazing rangeland, much of it publicly owned.

"Without large areas of public land, ranchers would have to graze private ground more intensively and couldn't grow hay to feed the sheep in the winter. Especially in the arid West, this could lead to overgrazing, damage to streamside areas, and increased costs for the rancher and consumer," says John W. Walker, an ARS range scientist with the station.

Many interests compete for use of this area, such as grazing, mining, development, recreation, and environmental concerns. When developing multiple-use plans, land management agencies consider all these competing uses.

Almost 100,00 acres of the Centennials, including the 16,000 managed by ARS, are currently being considered by the U.S. Congress for a wilderness designation.

Wilderness areas, as defined by the 1964 Wilderness Act, allow livestock grazing but exclude road construction, motorized use, and other activities that would disturb the pristine character of the environment.

The Centennials have been recognized as a critical biological corridor that links the northern mountain ecosystems with the Greater Yellowstone in the south. The area along the Continental Divide is a way for grizzlies and wolves to move between these large wildland complexes, says Bart Koehler.

Koehler represents a 6,000-member coalition of 100 environmental groups working to preserve and restore an 18-million-acre area known as the Greater Yellowstone ecosystem. The area includes Yellowstone and Grand Teton national parks, eight national forests, and additional public and private land in Montana, Idaho, and Wyoming.

ARS' portion of the mountains includes parcels of 12,855 and 3,760 acres, comprising three grazing allotments of 500 AUM each. An AUM, or animal unit month, is the amount of forage required to support five ewes and their lambs for 1 month. The sheep travel through additional public land to get to and between the parcels.

"Because the sheep station summer range is right in the wild heart of the Centennials, ARS has a large responsibility to make sure activities they pursue are compatible with the exceptional wildlife, scenic, and recreational values of the area," Koehler says.

ARS' Walker agrees. "We use a moderate stocking rate and rest one of the three allotments every year. Even in grazed allotments, half of the vegetation is left ungrazed. Most of our research, and our contact with the herders that move the sheep, is done on foot or horseback," he says.

He notes that there is enough food in the summer to support the sheep and the wildlife, so none of the wild animals lose out by the sheep's presence. Trained guard dogs help protect the sheep from coyotes, bears, and other predators.

Why in the Mountains?

One important reason for keeping the sheep in the mountains is to support decades of breeding research conducted at the station.

"We would have to start over if we changed the research environment now," says Gary D. Snowder, an ARS animal scientist at Dubois. "These sheep have been selectively bred to thrive under range conditions similar to those used by most sheep producers in the Intermountain West."

Breeds like the Targhee have been studied using this management scheme since their development by ARS in 1926.

An ongoing research goal is to maximize the weight of weaned lambs. "Over the years we've seen significant increases in lamb growth and total weight," Snowder says. He's working to continue the gains, and to produce a leaner meat for consumers.

Of equal value is the long-term ecological monitoring done by ARS researchers. In 1959 and 1978, vegetation was sampled on 111 sites in the summer range: the survey was repeated on half of the sites in 1994. "These studies help us assess the range condition over time, and they may he useful in determining effects of global climate change in the future," Walker says.

Photos from 1873 to 1947 compared with those taken in 1993 and 1994 show that once-eroded areas have healed.

A 1991 resource inventory by USDA's Natural Resources Conservation Service rated the range in good to excellent condition. And fences set up in 1959 to exclude grazing show no difference in vegetation inside and outside fenced-off areas.

But the landscape is changing—from lack of fire.

"We may have lost 20 percent of our range to conifers," says Walker. "Normally, fires started by lightning or other causes would have kept the forest from displacing sagebrush and aspen stands."

Some of the most sensitive areas are those along rivers, or riparian areas. Two creeks on ARS land, Tom and Odell, feed into the Red Rock Lakes Wildlife Refuge. Concerns that the sheep were increasing erosion of streambanks—causing degradation of the refuge's Upper Red Rock Lake 8 miles downstream—prompted ARS to consult an expert.

Charles Kay, a wildlife ecologist at Utah State University in Logan, studies willow tree and beaver populations, key indicators of riparian health. He found that the willows on the sheep station were in better shape than those in Yellowstone National Park and that moose, rather than sheep, were responsible for most of the willow browsing. Beavers were also plentiful.

"I found no evidence that sheep grazing—at present or in the past—has caused massive soil erosion," Kay says in the report of his findings.

Walker was not surprised.

Sheep prefer a more desertlike climate and are not attracted to riparian areas, he says.

Idaho rancher Brad Little says the ARS research has implications far outside the summer range.

"The sustainability of sheep ranching and of natural resources are tied. When decisions are made about whether to remove livestock from an area, research like this—tracking how a piece of real estate responds to management—will help make the difference," he says.

Little grazes 4,000 Targhee, Columbia, and Rambouillet ewes and their lambs on several hundred thousand acres of public rangeland. Research by Walker and others has shown that sheep can he used to manage noxious weeds, such as leafy spurge, spotted knapweed, and tall larkspur.

"They will often eat the weeds along with the other rangeland plants, and their preference for the weeds can he improved with training," says Walker. "And while you can't tell a herd of deer where to go, you can tell the sheep."

ARS research and education have also helped improve relations with local environmentalists. Now there are fewer conflicts on the range, and ARS research is largely compatible with the proposed wilderness designation. To further inform the public about the station, ARS scientists participated in a Greater Yellowstone Coalition meeting in May 1995. "We're trying to work together to find solutions everyone can live with," Koehler says. — By Kathryn Barry Stelljes, ARS.

USDA-ARS U.S. Sheep Experiment Station, HC 62, Box 2010, Dubois ID 83423; phone (208) 374-5306.


Signs Along the Continental Divide

This summer, ARS will begin placing signs at intersections of the ARS summer range and the Continental Divide National Scenic Trail. The signs will help visitors understand why the sheep are brought to this remote area and how the animals affect the landscape.

"The areas where the sheep bed down for the night may look trampled right after they leave, but by the next season you can't tell they were there," says ARS range scientist John Walker.

The trail winds over 15 miles of ARS land, at an elevation of 7,500 to 8,500 feet. A small number of visitors use the trail, while several thousand camp, hunt, fish, and snowmobile in the Centennials.


"Sheep at Home on the Wild Summer Range" was published in the June 1995 issue of Agricultural Research magazine.

Last Modified: 2/1/2007
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