all three of them have very different interests in seeing how this works out. >> suarez: christopher boucek of the carnegie endowment, thank you for joining us. >> thank you. >> woodruff: now, is the gray wolf a growing and threatening predator? or a pivotal player to 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. >> reporter: even on a good day running a cattle ranch is a mighty tough way to scratch out a living. when i meant rancher martin davis, he was not having a good day at all. >> looks like about half of our cows are down when they're not supposed to be. >> reporter: 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. >> i think they're all gone. >> reporter: 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. (