I had a fox enter the back of our barn while I was sweeping the floor, and it grabbed a kitten, Out in the fields I was with our horses when an orange cat ran from the woods, climbed me and ended up on my head peeing (gross) while a fox ran up and sat in front of me. Not much discourages them, but a dog is your best bet. We also build a 'fox gate' on the back of our barn made with old wood and lattice so that we could aerate the barn but keep foxes out. We used chain link on our windows. We have coyotes too, so our coop and run are like Fort Knox. All that stuff about nocturnal behavior is bunk. The only think that works is barriers, vigilance and a very aggressive dog.