Witnesses told KSL-TV that the man wanted the animal to head his way for a photo op and rattled a nearby fence.
"He had to have done something to catch the [bison's] attention, because that's when he turned around and decided to pay him a visit," a witness from Boise, Idaho said.
"[The bison] just was not comfortable with how close he was hanging out with him."
Pistorius testifies he didn't consciously pull trigger when he shot girlfriend
Biologists detail four new deep-sea 'killer sponges'