These kind of fights always seem to happen because of a lady. Recently, two bison bulls went head-to-head in the middle of a road in Yellowstone over a cow looking for a mate.
This is the time of year where you can expect that bison will be a little more emotional than others. A driver through Yellowstone learned this get got yelled at by a ticked off bison.
There are few sounds on earth we enjoy more than the roar of a Yellowstone bison...