In Idaho's rugged ranch country, a young calf killed by predators is every rancher's worst nightmare. For veteran biologist Rick Williamson, it's the beginning of a wildlife version of "CSI."
"There's a blood trail through here," Williamson observed. "We need to have the evidence to suggest what happened to this calf."
Wolves have been spotted in the region, but so have coyotes, bears and mountain lions. As part of his investigation, Williamson conducts a necropsy — an animal autopsy — right on the spot. If a wolf is responsible, the rancher will be compensated, and the wolf pack possibly hunted down.
"We are looking for feeding patterns that would suggest wolves [which] feed differently than coyotes or red fox or black bears," he said.
Such scenes are playing out across the northern Rocky Mountains as the growing wolf population — once endangered — leads to more and more conflict.
In the shadow of the Boulder Mountains, "Nightline" set out with Carter Niemeyer, a government scientist who's spent more than 20 years in the thick of the wolf debate.
Gray wolves once roamed freely in the West, and now they are back, stirring fear, stoking passion and inspiring awe.
Niemeyer says he isn't sure what it is about wolves that inspire such strong feelings.
"I have never really been able to put a handle on that," he said, "other than the lore, the mystique the fairy tales. … People talk about werewolves, little red riding hood, three little pigs."
By the 1930s, the wolf had been hunted, trapped and poisoned to near extinction, saved only by the Endangered Species Act. Then, in the mid-1990s, 66 wolves from Canada were reintroduced into the northern Rockies, and they now number about 1,500.
Niemeyer calls the resurgence of these wolves "one of the greatest conservation success stories that's ever been accomplished or achieved."
But that success also meant that, in late March, wolves lost their endangered status, making them fair game for ranchers and hunters. Now, age-old tensions again roil the West.
The Soulen family has raised livestock since 1929 on a sprawling ranch in western Idaho. Now, father and son run the ranch. It is hard, demanding work, branding lambs, docking their tails and preparing their flock for the annual 100-mile trek to a summer range up in the mountains. Last summer, some sheep strayed.
"We had about 150 head pull off from the band and they pulled up onto a ridge one night and bedded down," Harry Soulen said. "The wolves got into them and by the time the herder gathered up the remnants, we had lost 63 in that one incident."
Over the last three years, the Soulens say they've lost more than 800 head of sheep to wolves, which has had a "huge" impact on their livelihood.
"In a way it's a little bit like a thief or a shoplifter," Soulen said. "Each one of the incidents doesn't break you but day after day, night after night, you are losing sheep; after a while it adds up to some serious money."
Now, the Soulens and other ranchers have every right to kill wolves that threaten their livestock.
"We need to take wolves," said Harry's father Phil Soulen. "They need to be reduced. The numbers need to be reduced."
Harry Soulen said that the ideal number of wolves in the state of Idaho, from his perspective, would be "zero."