You're Afraid of What?

We were walking to school when the blond twin said, "You know what I'm afraid of?" I replied, "No, what?" She said, "Bison."
After a few steps pondering this answer I said, "Ok, I'll ask. Why are you afraid of bison?"
It turns out she was reading a book about wolves and a pack of wolves attacked a bison. Before the wolves could feast another bison managed to spear a wolf and kill it. This is why the blond twin is afraid of bison.
Now, as fears go this one isn't so bad. Really, what are the chances of the blond twin encountering a bison any time soon?