LIVINGSTON -- There are very few legal ways to kill a federally protected wolf, but rancher Randy Petrich found one Thursday.

He caught a wolf in the act of eating one of his calves.

It is only the fourth time since wolves were reintroduced here in 1995 that a wolf has been shot in the middle of a kill, said Joe Fontaine, a wildlife biologist for the U.S. Fish and Wildlife Service. Two cases were in Idaho and one in Big Timber.

"I knew you could only shoot a wolf if you saw it killing one of your cows," Petrich said. "I saw a black wolf right on top of this calf, feeding on it. I knew the green light was on and all systems were go, so I let him have it," Petrich said.

He used a .22-250 rifle he keeps in his tractor, then called a federal trapper, ho took pictures of the wolf and calf carcasses.

When a rancher has proven a wolf killed one of his animals, the rancher can get a 45-day permit to shoot any wolf he sees on his land. Petrich plans to apply for the permit, but says he probably won't kill any more wolves.