If one plans to free range at all (and this includes supervised free ranging - foxes around here are brazen), preemption is the best policy. Preemptive removal of chicken eating vermin will never entirely remove the threat, but the overall frequency of attacks can be minimized.
We keep three havaharts set on approaches to property (drainages), two leg hold sets, three deadfalls, and use of poisoined bait as necessary. This is the first year (in ten years) that our coon harvest has dropped from the usual ~20 by this time of year to a mere 8. However, fox population has rocketed (between neighbors and ourselves: 13! - usually ~2 by Sept.).
For ease of use/cleanup on havaharts: Use a couple of lengths of 1"x1" under trap on either side (keeps animal from digging up yard, etc. into trap - waste falls through. Place a twenty pound paver or big flat rock on top of trap as this prevents the smart ones from tipping trap over or setting it off from the outside.
Even with these methods the oddball will sometimes get through (baby monitor saved the day a couple of weeks ago). I had been letting out the chooks at dawn owing to the extremely high temps (6ft. Welded wire fencing) came back in, took a shower. Got out of shower and heard all h**l breaking loose! Grabbed rifle and ran `au Rousseau' into the backyard. Nasty `possum had scaled the fence and the roo had it cornered (lost his tail feathers in the skirmish). So, yeah, `poss are nasty and will sometimes attack after dawn!
IMHO relocation is slow death, humane recycling via Turkey Vultures works out for the Turkey Vultures.