Bison headbutts car in Yellowstone National Park

This large bison was standing still in the middle of the road, so cars stopped in both directions with plenty of room between them and the bison. Along comes another bison from the valley, up to the road, much closer to car. The larger bison then decides to walk over to the smaller (yet still large) bison. That's when this happened. Just think if he really put all his force into the ram. Luckily no one was hurt, not even the bison.