ENTERPRISE, OREGON -- As we climb out of Enterprise and up the Lostine River drainage in a white Cessna 206, Oregon Fish and Wildlife technician Crystal Strobl picks up a radio collar signal. Joe Spence, a chatty pilot who has flown over the Wallowa Mountains for years, then spots the first band of sheep. They stand in a herd, some on top of a ridge above Deadman Lake, others directly below them, calmly perched on the sheer cliff sides. It's late May. 

We circle the ridge near Deadman in tight, banked turns, and my sheep-counting efforts turn into focused meditative breathing meant to keep my stomach in proper orientation. The breathing is unsuccessful. Strobl, on the other hand, seems completely unaffected by the plane's diagonal attitude as it spins around a column of smooth mountain air; she efficiently counts 42 mountain sheep with 17 lambs. A small band of shaggy mountain goats grazes a higher ridge top. Near Frances Lake we spot another large group of sheep that includes five lambs. 

"The lambs in the Lostine seem to be doing really good this year," Strobl announces over the radio. 

The Wallowas rise suddenly out of eastern Oregon farm country, a steep mound of rocky peaks faced with grassy bowls, exposed ridgelines and high-mountain lakes. To the east, the peaks give way to canyonlands that cradle the Imnaha River and the wild, winding Snake River, home to Hells Canyon, a slash in the earth deeper and more rugged than the Grand Canyon. We head east into the canyon, where Strobl observes several more bands of bighorns, many including lambs. 

Mountain sheep vanished from Oregon in the 1940s, disappearing even earlier on the Idaho side of the canyon. Now they're back, at least to some degree. But whether these iconic animals will ever return to their historical levels is not yet clear. 

For at least 20 years, biologists have recommended keeping domestic and wild sheep apart on the range. Years of research have shown that when bighorns interact with their tame cousins, massive bighorn sheep die-offs soon follow. 

Nearly 20,000 domestic sheep still graze on parts of the Payette National Forest in Idaho, which contains ideal range - for both domestic and wild sheep - and is contiguous with Hells Canyon. New telemetry data have confirmed what biologists long suspected: Wild sheep from Hells Canyon are roaming onto domestic grazing allotments on the Payette. 

This summer, the Forest Service for the first time barred domestic sheep from those parts of the forest that connect with bighorn sheep habitat. That decision was upheld by a federal judge. But the recovery of the bighorns may depend, ultimately, on the outcome of a continuing legal dispute between supporters of wild sheep reintroduction and longtime domesticated sheep ranchers in Idaho. 

The battle for the Payette promises to clarify where bighorns will be protected. At the same time, it may determine the future of the sheep-ranching industry, which has depended on access to public grazing leases across the West for more than a century. 

Early snowstorms blanketed the high peaks of the Wallowa Mountains. It was late October 1939, and Don Moore had been sent to find the last of Oregon's wild sheep. The snow was an advantage in one way - it drove sheep lower, where they would be easier to spot - but it also made travel difficult. 

A young Oregon State College graduate, Moore used his base at Lick Creek - now part of the Hells Canyon National Recreation Area - to speak with ranchers, poachers, pioneers and biologists. He heard stories of abundant mountain sheep that once inhabited the rugged country between the Wallowas and the Snake River Canyon and recorded the tales in a small field notebook. 

E. M. Titus, a stockman, remembered the band of 16 mountain sheep that clung to the steep canyon walls above Temperance Creek, now a popular stop for Hells Canyon boaters. Those sheep disappeared between 1926 and 1928. Titus blamed the loss on blasting for a new trail along the Snake. But Moore pointed out that in the 1920s, domestic sheep were replacing cattle on the Hells Canyon rangeland. 

Charles H. Seeber, who had rented out boats on Aneroid Lake for 50 summers, saw numerous mountain sheep grazing down from the high peaks. In the spring of 1939, however, Seeber spotted only two. In block print in his little notebook, Moore wrote: "Mr. Seeber attributes the decline of mountain sheep to competition with the domestic sheep, as mountain sheep used to be very numerous in that area until domestic sheep were brought in."

After two weeks in the mountains in 1939, Moore was discouraged. "No sheep or tracks of sheep were found," he reported back to the U.S. Biological Survey, precursor to the U.S. Fish and Wildlife Service. And in his report, Moore posed a question that has been asked - and to some degree answered - this summer, nearly 70 years later: "Are mountain sheep in the Wallowa Mts. of more value to the people of the nation as a whole than is the grazing industry in this area?" 

Rocky Mountain bighorn sheep were once the dominant big game animal in the intermountain region, ranging from British Columbia south through the intermountain West and into isolated parts of Arizona and New Mexico. Wild sheep species are also found in Alaska, along the West Coast and in the desert regions of the Southwest. Dale Toweill, wildlife species coordinator for Idaho Fish and Game and co-author of Return of Royalty, a 1999 volume detailing the restoration of wild sheep in North America, says that of the approximately 2 million bighorns that once roamed the region, only about 35,000 remain. 

At one time, an estimated 10,000 bighorns inhabited nearly 6 million acres of steep canyon walls and rugged high country in Oregon, Washington and Idaho. Native people used the sheep for meat, clothing and tools and crafted a small, technologically advanced bow from the horns. The Indians left numerous depictions of bighorn sheep on rock outcroppings; some of these petroglyphs can be seen today along the Snake River. 

Domestic sheep, which share a common European ancestor with bighorns, were brought to central Idaho in the 1860s and to Hells Canyon in the 1880s. Large-scale wild sheep die-offs began soon after; they were often attributed to scabies, a skin mite. Though wild sheep persisted through the 20th century in central Idaho, they were essentially extinct in Hells Canyon by the 1940s. 

In 1971, Oregon Fish and Wildlife biologist Vic Coggins chose a spot on the Lostine River drainage to introduce a herd of Canadian bighorns. He would spend the bulk of his career restoring the animals to the greater Hells Canyon area. And restoring them again. And again. 

Idaho and Washington joined the bighorn-restoration effort in the 1980s, when a deep-pocketed hunters' group, the Foundation for North American Wild Sheep, increased its funding for sheep transplants. In 1997, the three states formed the Hells Canyon Initiative to coordinate reintroduction efforts and to work with federal agencies and the foundation. The states have transplanted more than 600 sheep up and down Hells Canyon since the 1970s, with a goal of having 2,000 bighorns in the huge Hells Canyon Initiative area by now. 

Instead, the population is declining, with only about 870 bighorns in the canyon. And this year, as summer went on, biologists reported more and more dead lambs. The bighorn problems still seem to be tied, somehow, to the presence of domestic sheep. "One of our charges was to try to figure out why these populations weren't increasing at a more rapid rate," Coggins says. "And we have, as far as I'm concerned. 

"It's the disease."