Littlecimmaron18, way to go, better a small run, than no need for a run at all
Here in Cent.MO. the foxes were breeding back in mid-Feb. (`screamy' yips and yaps during the nights for about a wk.) I'd guess about another two wks, or so before the vixens start throwing litters, and about a month-and-a-half before before they start going blood simple at the sight of a chook.
Burning out dens, without close observation (too time consuming a process) is a `loss-leader' (most effective weapon at a den is a couple of dogs - some folks keep dogs so they won't have to witness the deed themselves). There was a group of flock keepers (sheep) in this area of the county that were very active buring out dens until 1999 and, IMHO, they spent way too much time at it. They were criticized by a group that shalll remain nameless; so they `quit' being so obviously systematic . This, along with continued development, to the south, has resulted in an explosion in the fox population....
I would guess if you didn't kill it (them), you made them move elsewhere. If you continue to free range keep a shotgun/rifle handy (foxes are brazen); another hen wounded probably indicates the freeloader merely `redeployed'.
Padded jaw `leg' hold traps are allowed for Red Fox in Colorado (Call your DNR for exact `nuisance' trapping specs). That, and enough lead to pith them is probably the most humane method of retiring this chicken eating vermin. Far more effective and quick than letting the motorists on I-70/25 do the work in their inexact fashion.
You take care, I'm sure your survivors appreciate your efforts.