If you are going to continue to free range while you are away from home, you might consider getting your own predator....a LGD. That's how most of us manage to free range successfully, without losses to predators. If not this way, then a few chicken tractors that are pretty predator proof and locking up in the coop each night. Free ranging without the proper precautions is like opening a buffet for predators. Come and get it!!!
I've not lost a free ranger yet to predation but only because I've had some of the best dogs ever. If you can't provide this level of protection, then free ranging is not going to be trauma free for you. Expect more of the same in the future, as you can't possibly kill ALL the potential predators in the area. Good luck with your flock! Sorry about your good bird....things will get better. :aww