Abundant voles and field mice, ground squirrels and snakes provide a smorgasbord for the prairie's 12 raptor species, says Fields, a biologist for The Nature Conservancy, an international nonprofit that buys land for environmental preservation.
The 10,000-foot granite peaks responsible for its "Switzerland of America" reputation define Wallowa County, but between such geologic extravagances as the Eagle Cap Wilderness and Hells Canyon stretches the Zumwalt Prairie, one of the continent's biggest intact bunchgrass savannahs.
Part of the 150,000-acre grassland is getting a face-lift this summer.
Within the larger prairie, The Nature Conservancy runs a 33,000-acre preserve, where crews are removing a dozen earthen dams and stock ponds. The obstructions choke flows to downstream rainbow trout and steelhead fisheries, or they have overflow channels that erode the prairie and cause sediment buildups.
"We are trying to restore the natural stream flows," Fields says.
The project is part of a larger effort on the prairie to protect the plant and animal habitat. Here's a place where acre-by-acre, dam-by-dam, weed-by-weed, conservancy ecologists and volunteers are working to restore spots where homesteaders replaced the original native grasses with less hardy domestic grasses and made other changes. Efforts also are under way to better understand and safeguard such native species as the Columbian sharp-tailed grouse and quaking aspen, and fences are going up to protect sensitive areas.
The prairie offers a feast for researchers looking into everything from the rare western bumblebee to using aquatic insects to diagnose the health of prairie streams. Since the conservancy bought the preserve land 10 years ago, it has studied how levels of grazing affect wildlife and partnered in research examining the impact of invasive weeds on native and introduced grasses.
The dam removal -- along 19 miles of Camp Creek -- comes courtesy of the conservancy and the U.S. Army Corps of Engineers, which is picking up 65 percent of the $400,000 cost. In all, about 200 dams are sprinkled across the preserve, many built in the 1950s by ranchers for their livestock. Another 800 are scattered elsewhere in the Zumwalt grasslands.
Some geologists claim Oregon was born here, 120 million years ago, when the expanding North American continent crashed into a cluster of offshore Pacific islands like a runaway ship collecting rowboats on its bow. The result: the spectacular pile-up of the Wallowa Mountains; the creation of Hells Canyon, the deepest chasm in North America; and the Zumwalt Prairie.
Shoshone legend has it that the first humans originated here, too, in a cavern at the bottom of Hells Canyon, wrote historian Gale Ontko, author of the "Thunder Over the Ochoco" series. The Zumwalt Prairie, named for a family of homesteaders, is the largest fragment remaining of 20 million acres of grasslands that greeted the first Europeans in the Northwest. Much of that terrain now is planted in dryland wheat, peas, lentils and other crops, and the native grasses are gone.
"Grasslands are where we grow our food, and there are a lot of them that have been converted," says Steven Anderson, Nature Conservancy spokesman.
But here, 150,000 acres escaped the plows, largely due to the remoteness, high elevation (3,500 to 5,500 feet), short growing seasons and a population of only 7,100 in a county the size of Rhode Island and Delaware.
Native bluebunch wheat grass, Great Basin wild rye, Idaho fescues and other grasses carpet the rolling hills and wave in the wind. Spaulding catchfly, a sticky little plant on the federal Endangered Species threatened list, flourishes.
The prairie is home to about 430 plant species, 48 varieties of butterflies, plus numerous ground-nesting birds and aquatic species, Fields says. An estimated 3,000 Rocky Mountain elk spend part of each year on the prairie, as do black bears, cougars, Canadian gray wolves, mule deer, Rocky Mountain bighorn sheep and possibly even a Shiras moose from time to time.
Experiments with grazing, fire and herbicides expect to discover the best way to eliminate introduced grasses such as Kentucky bluegrass and tall fescues. Native grasses better resist invading yellow star thistle, medusa head rye and other noxious weeds.
Wallowa County has battled invasive weeds for decades, and local growers began something unique in Oregon almost 30 years ago, a "hay station" staffed by volunteers on Oregon 82 during the autumn hunting seasons. It aims to keep invasive weeds out by selling local hay to horse and mule owners venturing into the backcountry. Volunteers known as the "weed warriors" also spend part of their weekends killing spotted knapweed, leafy spurge and dalmatian toadflax and other invasive species.
Meanwhile, the conservancy partners with Oregon State University to research grazing's impacts on birds, soils, butterflies and spiders. The conservancy has leased allotments to ranches for about 800 mother cows plus calves this summer. The prairie, "as a system, needs a certain amount of disturbance" that cattle provide to prevent dead grasses from accumulating and help recycle nutrients, Fields says. The conservancy also is researching the best grazing practices on grasslands to share with neighboring ranchers.
The Nature Conservancy's holdings in the preserve include 18,000 acres of rolling prairie and 15,000 acres of canyon country and canyon grasslands on the eastern fringe. In Oregon, the conservation group owns or manages 47 preserves with 141,831 acres.
But the Zumwalt is special.
"I haven't met a student yet who hasn't been awed by the prairie," says Sandy DeBano, an OSU riparian entomologist who's part of a two-year-old program to bring undergraduates from around the nation to do grazing studies and other research.
"There are hidden corners everywhere," Fields says. "You almost have to walk it to really appreciate it."