Armed, supervised free range is the only ranging that goes on here. We keep all under-story and brush cut well back into our woodlines. Good fields of fire for us and plenty of warning time for the poultry. Many of our neighbors, in the surrounding area, also keep poultry and goats and so the Reds get triangulated via word of mouth.
Don't know how much property you're on, but foxes will usually cache large kills far enough away from kill site to feel both safe and be within an easy traveling distance to den. Usually, within days of the grab, that cache site will contain nothing but feathers. That is where to start hunting down the den (south facing hillsides/streambanks/under abandoned farm buildings/at the base of big Hickory/Oak snags).
Have had good luck with snares during the winter, but we've shot far more Reds than we've trapped ( several kits in the live traps/only one adult), 18 in 2007 - this year? only two - and someone was kind enough to hit one on the road by our mailbox). They are sly, but they go blood simple after they get a bite of chook. If caught in the act and it takes off, just get the rifle and wait a bit, it just has to come back. We've had the brazen Reds try to make grabs with one, or the other, of us within 30ft.
Can't get them all, but can sure knock down the overall frequency of attempted predation while `free ranging'.
Good luck!