JUDY WOODRUFF: Now, is the gray wolf a growing and threatening predator or a necessary player in the ecosystem of the Western U.S.? That's a debate playing out with real consequences in Montana, where a new gun hunting season began this past week.
NewsHour science correspondent Miles O'Brien reports.
MILES O'BRIEN: Even on a good day, running a cattle ranch is a mighty tough way to scratch out a living.
And when I met rancher Martin Davis, he was not having a good day at all.
MARTIN DAVIS, Flying Diamond Ranch: Looks like about half of our cows are down where they're not supposed to be.
MILES O'BRIEN: He runs the Flying Diamond Ranch, a small operation with 130 head of cattle in Montana's Paradise Valley. But there was trouble in Paradise on this day.
MARTIN DAVIS: I think they're all gone.
MILES O'BRIEN: His cows were not where he left them, in the summer pasture high in the mountains above his homestead. It was a mystery. But he had a prime suspect in mind from the get-go.
MILES O'BRIEN: Among ranchers like Martin Davis, the wolf is always guilty until proven, well, soon-to-be-guilty.
MARTIN DAVIS: Wolves and livestock don't mix. And it's just -- you know, maybe they will keep their nose clean for a short while, but sooner or later, the problem is going to occur. So we have got to have those numbers down.
MILES O'BRIEN: Martin Davis will soon get his wish. This feared, beloved, misunderstood animal once protected as an endangered species will be in the gun sights of hunters in Montana and Idaho this fall.
The Davis spread sits 50 miles northwest of Yellowstone National Park, where gray wolves returned 16 years ago after a 70-year hiatus. Starting in the early 1900s, they were systematically poisoned, trapped and gunned into extinction in the Lower 48, a good riddance for ranchers, an unconscionable extermination for environmentalists.
DOUGLAS SMITH, National Park Service: The frost bit my fingers today.
MILES O'BRIEN: Doug Smith is a lifelong lover of wolves who presides over their reintroduction to Yellowstone for the National Park Service. He's been here since the highly politicized media frenzy beginning in the mid-'90s.
Is this ideal wolf country?
DOUGLAS SMITH: This is. Some people said before we reintroduced wolves to Yellowstone that this was the best wolf habitat in the world, and had no wolves.
MILES O'BRIEN: The wolves are thriving here. They are, after all, at long last, home. What began with 31 individuals imported from Canada has blossomed into a population of more than 1,700. Only 150 of them live inside the park proper.
BILL SNAPE, Center for Biological Diversity: Oh, I think the success of the program has been a little bit beyond what most people thought in 1995. That's a great thing.
MILES O'BRIEN: Bill Snape is an attorney for the Center for Biological Diversity. The great success he heralds is seen by ranchers as a clear, present and persistent threat to their cattle herds.
Since the wolves returned to Yellowstone, they have been linked to more than 4,500 cattle and sheep killings, or depredations, as they're called. Using their political muscle, the ranchers got their members of Congress to put a provision in the federal budget bill that took the wolves off the endangered species list. They had been listed since 1973.
They claim the wolf population is now large enough to sustain hunting. And that has paved the way for wolf hunts this fall. Hunting season on the wolf is now open in Montana and Idaho. Montana will grant licenses for hunters to kill 220 out of about 600 wolves. Idaho has 1,000 wolves and will allow hunting until the population drops to 150.
That angers Bill Snape.
BILL SNAPE: They want to shoot hundreds of wolves through a private hunting scheme that would decimate the pack structure and really change the dynamics of the wolves' success.
MILES O'BRIEN: Snape's organization is one of many suing to undo the unprecedented relaxation of the Endangered Species Act by an act of Congress. It might very well end up in the Supreme Court.
But in the meantime, some ranchers here are trying to make a separate peace with the wolves. Andrew Anderson and Hilary Zaranek are trying a novel approach at the sprawling J Bar L Ranch in Montana's Centennial Valley, 40 miles from Yellowstone.
So what's the ideal bull-to-cow ratio?
ANDREW ANDERSON, J Bar L Ranch: One to 20.
MILES O'BRIEN: Damn, they're lucky guys, huh?
MILES O'BRIEN: They take a high-maintenance approach to managing the herd. Using electric fencing, they force them to cluster together, grazing intensively for a week or so and then when the grass is depleted, they stake out a new fence, move the herd on to the greener pasture.
They believe it's a better way to manage the grassland. But they're also taking a cue from native buffalo, which naturally herd tightly and thus are seldom attacked by wolves.
So, it's a lot of work for you guys.
ANDREW ANDERSON: It is. And in most cases -- in most cases that we're doing this intensive grazing, we have got these cattle in a much smaller area and we are moving this fence every day. And so it is a lot of work, definitely.
MILES O'BRIEN: You haven't lost any cattle to wolves?
ANDREW ANDERSON: That we know of, we have lost one calf in the last three seasons. And for the most part, we're at fairly high risk.
MILES O'BRIEN: And Hilary has the bones to prove it.
HILARY ZARANEK, J Bar L Ranch: You can see this -- his adult tooth is starting to come in right there.
MILES O'BRIEN: Yes. Why did this pack get shot?
HILARY ZARANEK: He was part of the Horn Mountain pack. And they lived back here. And they depredated a couple -- couple calves from the neighboring ranch. And the state decided to take them out.
MILES O'BRIEN: The government has always authorized the killing of so-called problem wolves. More than 1,500 have been killed since the wolves returned. And yet the push for open season on the wolf persists.
Given the way that the population has spread, is it healthy enough to allow a certain amount of hunting?
DOUGLAS SMITH: The short answer is yes. Wolves are tough to live with. They need tolerance from humans. Wolves aren't going to get that unless problems can be solved. It appears -- there's not really hard studies on this -- that social tolerance increases with wolf hunting.
So, I have got two wolves.
MILES O'BRIEN: You heard right. Doug Smith, the wolf man of Yellowstone, is OK with wolf hunting -- within limits.
DOUGLAS SMITH: I'm only getting those two.
MILES O'BRIEN: In fact, it turns out the gray wolf story is all about shades of gray and limits.
DOUGLAS SMITH: This habitat here is a lot more rich than the habitat over here.
MILES O'BRIEN: He took me to a place in Yellowstone called Crystal Creek framed by lush thickets of willows and aspen trees, home to songbirds, ducks and beaver dams.
DOUGLAS SMITH: In the last 10 years, every bit of what you have seen here has come on. It has just become luxuriant. There goes a young duck right there, popped in the water.
MILES O'BRIEN: What does all this have to do with wolves? Well, during the wolf-free years, the elk population exploded here. They overbrowsed places like Crystal Creek, and the willows and aspens could not get a foothold. With wolves hunting them again, one elk herd that's been tracked is down 60 percent.
The trees are back. And there is much more biodiversity as a result. All these ripple effects linked indirectly to the top predator have a scientific term: trophic cascade.
DOUGLAS SMITH: What truly is the impact of restoring the wolf and other large carnivores? Pretty big, we think. We're still working it out. I'm not discarding the effects of climate and water availability for plants. That's important, too. But you probably couldn't have this without that predator.
MILES O'BRIEN: And you wouldn't get this either. Wolves have become a star attraction here at Yellowstone.
MAN: We hope the wolves will be across the valley.
MILES O'BRIEN: Wildlife filmmaker Bob Landis has helped make the wolves familiar to millions with breathtaking images of the wolf packs of Yellowstone. He knows many of the wolves by sight and introduced us to his friends, a pack of wolf watchers who are out at sunrise every morning to follow, film, or just fancy the wolves.
MAN: Look at the bush. They're right behind it, are the wolves. They are up in that sage again.
MILES O'BRIEN: Yes. Yes. Wow. Wow. Look at -- they're just -- they're black, huh?
MAN: Yes, there's three black pups.
MILES O'BRIEN: Wow.
MAN: There's two black adults.
MILES O'BRIEN: God, that's really cool to see them playing like that.
The wolf is a creature that sparks an array of emotions as big as the Montana sky.
The wolves are -- they have this kind of iconic status. People love them or hate them. How do you explain that?
MARTIN DAVIS: I have no idea. You know, I really don't. I don't understand this predator that kills, where he does get that status as being this monarch of all predators. I really don't understand it.
MILES O'BRIEN: So what about the case of his wayward Gelbvieh cows? It turns out the salt lick was depleted, and the cows didn't seem too agitated.
What do you think happened? Was it a wolf?
MARTIN DAVIS: I'm guessing probably not. They seem fairly laid-back here today. And I'm guessing they just decided to wander.
MILES O'BRIEN: The struggle between cowboys and wolves is a story as old as the West itself. They're dueling icons, really. As they enter this next chapter, the real question is, how resilient will the predator be now that it is once again prey?