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Deaths of the Little Bighorns

A mysterious illness is weakening lambs in the Rockies, with many falling prey to predators. Researchers say pollution may be the cause.


WIND RIVER MOUNTAINS, WYO. — The baby bighorn sheep stumbled and collapsed on the stony tundra, too sick and wobbly to keep up with its mother.

Jon Mionczynski, a wildlife researcher who followed the pair, had seen this before. For some reason, lambs born into the largest herd of bighorn sheep in the Rockies were not surviving.

It would be hard to find a wilder, safer sanctuary, or so it seemed. But as scientists teamed up with Mionczynski to unravel the mystery, they learned that there is no such thing as pristine wilderness and no refuge from the Industrial Age.

Mionczynski nicknamed the struggling lamb "Rambo" because of its tenacity and pluck. Each time it fell, it struggled to its feet, even after blinding an eye in a tumble.

One evening, he was close to capturing Rambo for testing, but the lamb and its mother started down the mountain and, out of reach, hunkered down in a fortress of boulders near a crag called Lion Pass.

"I returned at daybreak and saw the ewe still guarding the site," Mionczynski recalled. "She made a low-pitched, throaty bleat, . . . brrrr . . . brrrr. It was like a sheep crying and it just went right through me."

When he got to the boulders, he saw fresh mountain lion droppings. "The ewe had a torn ear, blood running down her face and claw marks on the side of her head," he said. "The lamb was gone. That was the end of Rambo."

In a way, the natural order had prevailed: the strong picked off the weak. But something was unnatural too: What was making lambs so sick within weeks of their birth? Why were ewes leading weak lambs on arduous treks through cougar country to reach mineral licks at the base of the mountain?

The herd, which used to number about 1,250, plummeted by 30% in two years during the early 1990s and never recovered. Since then only about two out of every 10 lambs have survived.

In 1998, the Wyoming Department of Game and Fish told Mionczynski to set up a one-man camp at nearly 12,000 feet, track the herd's every move, study every foot of their mountaintop refuge, examine plants they eat and send back blood and tissue samples of dead and dying animals.

The job called for a meticulous observer and a skilled outdoorsman, someone who did not fear grizzly bears, or living in a tent in snowstorms and driving winds. For Mionczynski, it was the dream assignment.

"I have the best job in the world," Mionczynski said. "I'm just a peon in this research, but I like to think I am helping these animals."

Now, four years into the project, scientists believe they are close to solving the mystery. What they have discovered suggests that profound environmental changes are beginning to ripple through the food chain and into the bodies of lambs. They are learning that even these reclusive bighorn sheep, masters of evasion, can't escape pollution that falls from the sky.

As a result, Mionczynski and others fear, these icons of wild America may be unable to survive in the wilds without continual human intervention.

Town Takes Pride in Bighorn Sheep

A summer thunderstorm peels off the Winds, a fitting name for the mountain range west of Dubois (pronounced doo-boys), briefly spilling rain and hail over town. Tourists pull off of U.S. 287 into the National Bighorn Sheep Interpretive Center, the newest and most ornate facility in this two-lane town. It's located past the Ramshorn Inn Tavern, not far from the high school where the Rams play, a couple blocks from the Ramshorn Food Farm on Ramshorn Street.

"This town loves these sheep and we're proud of them," said museum Director June Sampson, leaning over the cash register. "In the winter, people can see them with spotting scopes from their living rooms. Hundreds of people come from all over to see the sheep."

Rocky Mountain bighorns have thrived in these mountains southeast of Grand Teton National Park for centuries. They are stocky and barrel-chested with petite feet that stick to rocks like suction cups. In the fall, rams charge one another and smash heads at speeds of 20 mph in battles that sometimes last all day and all night. Shoshone and Gros Ventre Indian tribes made powerful bows from the horns, which are still prized by hunters as trophies.

The herd inhabits the northern Winds in scattered bands. When they all converge on the sagebrush hills at the edge of town during winter, they constitute the largest group of wild sheep in North America. These animals were once so abundant that they were transplanted to establish new populations from South Dakota to New Mexico to Idaho.

Yet there are fewer and fewer sheep for tourists to enjoy. Barely 800 animals remain in the herd, which is still in decline. That prompted Wyoming game managers to dispatch Mionczynski to the mountaintop.

No sooner had Mionczynski set up camp on Middle Mountain in June 1998 than he observed many lambs as feeble as Rambo. Born healthy, they grew sick shortly after ewes made their annual spring migration to Middle Mountain to forage. If pneumonia didn't kill them, predators did.

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