DUBOIS - Bighorn winter range is a bitter-cold, rock-speckled place, where the slopes are blown bald by a constant coil of wind.

This icy wind - which would rip a flag to tatters in a few short days - is what makes this place ideal for Rocky Mountain sheep. It sweeps the area clear of deep snow, revealing the residual vegetation from the previous summer's growth.

Torrey Rim is such wind-swept country.

Until 1991, it and other slopes of the Wind River Mountains were home to the 2,000 or so bighorn sheep that made up the famous Whiskey Mountain herd.

Now, only about 700 sheep live here.

After a decade of decline, the Whiskey Mountain herd's population has been merely treading water for years, said Greg Anderson, wildlife biologist with the Wyoming Game and Fish Department.

He hopes an experimental medicated-feed program will help turn the tide.

It wasn't quite spring in the high country when Anderson went up Torrey Rim to see if he could get the sheep to take the bait. Four ewes and one young ram munched the frozen, hay-colored grass poking up through a dusting of snow - the first bighorns to trot into view that early April morning.

On a nearby slope, just a bit higher up, 50 or so elk were there for the same reason.

"They're slowly getting used to it," Anderson said, as he tossed more pellets onto the frozen terrain. "They like it; it's just a matter of getting them on it. You wouldn't think it would be so difficult taking an animal in the wintertime and getting them on high-quality feed, but boy, it's been difficult."

Last winter, Anderson began feeding bighorns the pellets to get them interested in the food. Next year, once the herd is accustomed to it, he'll begin using the medicated feed.

The animals looked healthy enough at the tail end of a hard winter. Still relatively muscular, their hides were thick, and they acted frisky enough to constantly push one another around. But they carry what biologists call a high "load" of lungworm. It isn't fatal on its own, but the worms burrow into the animals' lungs and create scar tissue, which makes the sheep more susceptible to diseases such as pneumonia.

As Anderson threw more of the alfalfa and oat pellets onto the frozen terrain - and as the sun reached higher above the Absaroka Mountains behind him - more sheep trotted out onto the rim in threes and fours, until finally there were a few dozen within 20 yards of Anderson's pickup.

The bravest sheep eventually trotted over to Anderson's feed line, and then some of the less brave followed. Not all of the animals were takers, however. Many stuck to the less nutritious, but more familiar, dormant grass.

A constant hierarchy is established and re-established among the animals. Even the ewes took breaks from feeding to push other ewes about and to rear up and butt heads with each other and sometimes with the young rams. The mountain silence was broken by the regular, sharp pops of horns cracking together.

The Whiskey Mountain herd used to be a well-spring for bighorns. It was the source population for transplanting sheep to many other cherished herds throughout the West, Anderson said. Then a catastrophic 1991 outbreak of bacterial pneumonia decimated the population.

The herd's numbers declined steadily for a dozen years following the outbreak, and they've finally begun to stabilize in recent years. But the Whiskey Mountain herd has yet to start rebounding.

"We used to have more sheep than we probably should have had," Anderson said. "Now we have fewer than we'd like to have."

Biologists have no simple answer for why the herd has yet to recover, but the most compelling theory at present is that a combination of drought - which has led to poor forage and inferior body condition, in general - coupled with the high load of lungworm, has made the population weaker and more susceptible to getting sick.

Once Anderson begins the medicated feed program this coming winter, it should cure the lungworm problem, at least, and remove one of the strikes against the animals.

It's an action wildlife biologists hope will lead to healthier lambs and, ultimately, a higher survival rate. Eliminating the lung parasite should make the animals less susceptible to the infections that have been killing them, especially the lambs, he said. The pneumonia that decimated the herd still lingers in the population, and it appears it is still killing some of the lambs.

"I'll see lambs up on the summer range mountains coughing all the time, and that's indicative to lung problems," he said.

The sky was perfectly clear, save a few wispy clouds, the sun was bright, but the air still carried the bite of winter. Bighorn sheep prefer wide-open spaces like this because one of their greatest assets is their extraordinarily sharp vision, Anderson said.

Their eyes have the approximate strength of 10-power binoculars. In a spot such as Torrey Rim, if any predators were approaching, the sheep would likely see them long before they got close enough to pose a threat.

Anderson looked beyond the sheep into the distance. Just below Torrey Rim, the water in Torrey Lake was still a wintry blue-black. Behind it, the barren folds of the Dubois Badlands lifted into a panorama that gave way to the jagged, snow-capped peaks of the Absarokas.

By next spring, Anderson hopes the animals will be free of the parasites that are damaging their lungs, and then perhaps this iconic herd will finally start its 21st-century comeback.

But first he's got to convince the more timid of the group to at least give the pellets a taste.

Environment reporter Chris Merrill can be reached at chris.merrill@trib.com or at (307) 267-6722.