Many visitors to Yellowstone think Bison are like gentle, placid cows. Making that assumption is a big mistake. Large male bison can weigh up to a ton. From Wikipedia:
“Bison temperament is often unpredictable. They usually appear peaceful, unconcerned, even lazy, yet they may attack anything, often without warning or apparent reason. They can move at speeds up to 35 mph (56 km/h) and cover long distances at a lumbering gallop.”
During the rut, in July and August, the bulls are totally focused on the task at hand. They pick a female and guard her from all other takers. Unlike the hype of some television specials, you don’t see bulls fighting to the death around every corner. They try their best to establish dominance through a show. Wallowing in the dust, roaring, pawing the ground are some of the highlights and usually convince one party or the other that some other female is a better choice after all. The bulls want the female’s complete attention and will chase away her calf. The females often seem to barely tolerate this.
You can judge the irritation level of a Bison by observing a number of clues – pawing the ground, how high their tail is raised in the air, and the the level of bellowing.
My lay judgement is that this guy is close to the “crazy bison” level and should be left alone:
