I lost my rooster and 2 hens to a fox that jumped over the 4 foot tall electric fence. Rehomed other 2 hens and built a taller fence.I called the state Wildlife department when I had a fox problem. Was told I could shoot the fox if I caught it in the act of killing chickens. However, could not go near the den as it was in a state park. A neighbor ended up killing the fox which solved the problem until the next fox moved into the area.
I solved the problem by buying Premier1 electric poultry netting. Fox got zapped and never came back.