I should call this the Angry smiling Bison as Bison usually do not show their teeth. So this is an interesting portrait of one. Actually this bison did not care for me either.I think that is why he is showing his teeth. He was a bit upset with me as he was not happy with me being in his area. Most times bison are pretty content and give/allow you a pretty wide berth around their space. but sometimes like people they are not in the mood to have their space invaded.Although I was not really that close, I had a telephoto lens. He was grazing in a secluded bush area in the Teton with a fellow bison and did not want anymore company so he gave me the signs that he was not happy and the smile was one of them,along with a few grunts and the stare down. So I gave him his space (as I don't have a death wish)and was left with this image.. A animal will usually let you know when you have crossed or are near crossing that line where he has drawn. Respect them and back away if they show signs of being agitated or uncomfortable with your presence.. Telephoto lenes are great for being able to get close without either one being hurt,which usually will be you.These animals are capable of running up to 30 mph.It would be like being hit by a Mack Truck. Taken Grand Teton National Park,Wyoming