How do you know those stories are true? I've heard a lot of stories as well, but I've seen some of the chicken predators in action and frankly, I'm very skeptical about a lot of the stories I've heard. I'm afraid that too often they are like fisherman's tales about the size of their catches. )
One of my Iowa Blue roosters fought off a weasel.
If you would like more information, you can look up the iowa blue chicken club website.