I was deer hunting by myself in the Hoback drainage in Western Wyo in the mid 90's. I had hiked way up high to timberline at daylight and was sitting under one of the highest trees glassing an alpine basin. I'd gotten hot and sweaty hiking up for an hour, so I took off my coat and was cooling off. Heard a twig snap behind me and looked - a BIG boar black bear at about 20 yards stalking me.
I stood up and hollered at him. He moved back and I threw some sticks, and he eventually went up and out of sight.
About 5 minutes later, I had one of those "premonitions" and looked over my other shoulder. There he was again. This time, he would not leave. He snapped, growled, stood and raked trees with his claws and walked back and forth on a log while clacking his teeth and hiking one leg at me. He finally stepped off the log and stood up high clacking and growling.
At that point, I said "Don't take one more step toward me you SOB" and he naturally stepped toward me. I shot right between his front feet with my 300 and duff and crap flew everywhere. He wheeled and ran off, but only then did I realize what an athlete he was. He was 19 feet away when I shot and I'd be a bear turd today if he would have come down the steep hill at me instead of running off. I am sure he would have hit me before I could have chambered another round at that distance.
Talked with the Game Warden afterward and he said I could not shoot the bear without a license unless it actually touched me. He also said that was the area where they release many of the problem bears who are accustomed to people from Jellystone Park.
If it ever happens again, I'm stacking up the bear.
Also, last year we had a griz come through camp at 12:30 in the morning while sheep hunting east of Yellowstone. Two of the horses broke their tie outs and we were out in the dark in our undershorts and slippers with headlamps chasing horses for 20 minutes. No bear problems, but it was scary after we realized we could not see hardly at all and a bear could have been 50 feet from us at any time.
Last year, I saw 17 griz in 3 days of scouting there and 12 griz in 2 days of hunting. Those buggers are everywhere.