I'm not surprised this happened.
Bison are often perceived as less of a threat than bears because they don't look "look" dangerous when they're just standing around "chewing their cud", or whatever.
Well, they are...
http://www.foxnews.com/us/2015/05/17/gi ... latestnews
6 feet is insane.
And the cows are especially dangerous this time of year when they are calving.
It's best to give bison wide berth.
pete