To the poster: Is your JRT ok with the chickens? If you leave them in the yard together I do not think a fox will come around. Dogs can smell that foxy musky smell from very far away and will be on the lookout. It will just encourage the fox to look elsewhere. That's easier than having the chickens locked up all of the time, and better for the fox too- in lots of places they are having a real hard time finding food and keeping their number up, and they are important in keeping other prey populations under control. Maybe he'll try hunting other pests for you.