Bison of Yellowstone
Many images, please scroll down.
Above (1): image taken from a safe distance away with a telephoto lens. More humans are injured by bison in Yellowstone than by any other species.
Above: a common problem on Yellowstone roads --- the bison think roads are for walking upon!
Above (6): a bull attempting to mount a cow in a most inconvenient (for motorists) place. Image taken from inside the van --- bison can be dangerous, even without raging hormones. These animals all left the road without further displays.
The bison in the above image (7) are watching wolves dismembering a recently killed elk. It was not clear what the bison thought about this, but bison are known to defend themselves aggressively against wolves and to chase wolves away from kills.