Currently I have my 11 chickens free ranging on about 2 1/2 acres. The yard is fenced in with electrical fencing to keep out fox/coyotes. Recently I lost my rooster to a hawk. I want to build a run for my girls to keep them safe from Hawks when I'm not home. How concerned do I have to be with securing the run from foxes given the electrical fencing around the perimeter of the yard?