The buffalo hunter calls himself "Mr. Mike" and he’s retired from the Boston police force, and lives in Billings. He walks with a cane and moves slowly from injuries sustained in a crash that ended a high-speed chase, years ago. He’s shooting a .270, which is light for buffalo, but sufficient in the right hands, which Mr. Mike happens to have, since he does a lot of benchrest and other kinds of shooting. He has just walked up to the edge of this Forest Service horse pasture, perused the two immense bull buffalo standing 100 yards behind it, rested his rifle on the fence, and slammed a bullet into the 2-inch-by-2-inch space behind the biggest one’s ear. The bull dropped straight to the ground. It was a kill so clean that it was lauded even by some Buffalo Field volunteers watching from a nearby ridge with binoculars.

Mr. Mike is unfazed by the presence of the Buffalo Field Campaign people and their act of witness; he’s unfazed by the utter unblinking and condemnatory silence of the tall bearded young man in a long wool coat, who points his video camera at Mr. Mike as if, rather than recording his hunt, he would like to erase him from the scene. Mr. Mike is a fast-talking, story-telling man, unabashed South Boston accent. He’s happy about taking down the bull, telling me right off that he’s planning to write about his buffalo hunt for the Safari Club Magazine, in a section he writes about big-game hunting opportunities for the disabled.

We walk out into the horse pasture, focused on the dead bull’s sidekick, a not-much-smaller buffalo that is standing off to one side, tail half-raised. If a buffalo’s tail goes straight up, people tell me, the rule is, "it’s gonna charge or discharge." I’ve got on what now feels like a garish blue jacket, and am hoping I am not going to be remembered as the fool who was flattened during the first buffalo hunt of the 21st century.

"You can’t haze these things," says the man who takes care of the property. As we try to do just that, one of the local boys who has volunteered to help Mr. Mike with the formidable task of gutting and caping the bull adds, "These are the stupidest animals on earth." But Mr. Mike is unfazed by that pronouncement, too. He’s listening carefully to one of the Buffalo Field people, a clean-cut man who works in the park as a naturalist and is explaining why they are documenting the hunt, what they would like to see changed about the way the state treats buffalo.

Mr. Mike, it is clear to me, is exactly the kind of hunter who might understand that, in order for hunting to have any meaning, you have to give a little bit to the game animals. He is about to lay out almost $2,000 to have the bull mounted, and, as he sits on it, rifle in hand, for the trophy photos, he’s proud of the beast, proud that it’s an old bull with a thick coat of hair that looks six inches deep, hair that is bleached by years of sun and the winds of the high country, proud of the scar on the bull’s flank that we decide was received in some violent contest with another bull. It may sound odd to a non-hunter, but there is respect there for that bull. It is the kind of respect that has translated into the American wildlife conservation ethic, arguably the strongest and most unique conservation ethic in the world — an ethic that has so far not been applied to the buffalo.

While the volunteer helpers discover just how difficult it is to field dress a 1,900-pound animal with skin like a six-ply tire, Mr. Mike and Mike Mease exchange addresses, so that Mease can send him a video of his hunt. They shake hands, and we leave, just as the local boys start chopping at the bull’s pelvis with a single-bit axe somebody has produced.

Farther up the Eagle Creek road, a bullet struck a buffalo bull somewhere around the left side of his head and knocked him down, rolled him, the witnesses told me, so that his feet were straight up in the air. Then the bull got up, and a second round drove him down again. The boy was shooting a .270 like Mr. Mike, but he was hitting just a little bit off, maybe because the rifle was sighted in for 100 yards or more, and they were much closer than that to the bull. A little bit off would put a fairly light bullet up against the heaviest mammal skull that North America has to offer.

When we first get there, the shot bull is up again, and climbing straight up the face of a barren ridge about 500 feet high. He never runs, but his shuffling progress, huge shaggy head bobbing up and down, is deceptively fast. He hits the top of the ridge and disappears while the boy who shot him stands there with his father, his sister and his brother, in the snow and sagebrush beside the road, watching him go.

On the other side of that ridge is the big basin of Eagle Creek, sprawling and undulating sagebrush country, the ribbon of willows enclosing the creek at its center, fingers of aspen at its perimeters. The shot bull crosses the spine of the ridge and bears on uphill, through little knots of wintering mule deer, below a small band of elk. His tracks in the snow merge with the tracks of dozens of other buffalo, some of which raise their heads to watch his inexorable progress. There’s no blood trail, and we drive up the road, following a game warden’s truck, hoping to be able to tell the hunting party, when they arrive, which of the many buffalo out there is the one that needs a finishing bullet.