Rats, raccoons, possums, hawks, neighbour cats. I rarely see hawks in my area, but one day a Cooper's Hawk was sitting on my pen looking hungrily at my birds.
They definitely can not free range. They are wilder than coturnix quail, but they can be tamed with enough time and effort. They require warmer temperatures. If you're going to keep them outside, they may need some extra heat during the winter.