Rick Christy said he was awakened by the commotion at about 5:30 a.m. Tuesday. It was light enough outside for him to clearly see two bears in his sheep pen.
Christy killed one of the bears with a single shot from a .308-caliber rifle. The other bear fled, but not immediately.
"I was motivated," Christy said of the single shot. "The best shots are the ones you don't think about. At times, the bears were within 10 feet of me."
Christy said the bears were chasing sheep around a concrete manure bin in the middle of the sheep pen, which is long and narrow.
"The sheep and bears were all running around that, and I didn't know how many bears there were," Christy said. "I shot when they jumped on a sheep right in front of me.
"The bears were not bothered by my presence. Even after I shot the one, the other one just slowly took off," he said. "They both were about the same size."
Christy said the bears killed or fatally wounded nine sheep, including ewes and a lamb. He said two sheep were sewn up by a veterinarian, but the others were either dead or too far gone to save.
The sheep were either young or had special genetics. Most of Christy's flock of sheep is in Idaho on a Bureau of Land Management grazing lease. He estimated the value of the dead sheep at $1,800 to $2,000.
Bear managers from Montana Fish, Wildlife & Parks and the federal government went to the scene right after the attack.
Brian Lake, a U.S. Fish and Wildlife Service agent, said the bear shooting remains under investigation. Christy said Lake gave him back the rifle he shot the bear with after Lake questioned him.
FWP bear management specialist Mike Madel said the dead bear was a sub-adult male in good shape, was probably two or three years old and weighed about 300 pounds.
Madel said he believes the other bear is a sibling of the dead bear. He and other bear managers have set traps to try and capture the remaining bear. They left the dead bear's carcass in an area on the Christy ranch to help lure the other bear back, Madel said.
The second bear fled the Christy sheep operation and may have returned to one of the coulees that lead to the Sun River.