Since our neighbor's dog killed 2 of our sweet hens, we built a chicken yard out of hardware cloth and fence stakes, so the girls could still range, but would be safe from dogs. Everything was fine for a few months, then we started finding them outside their fence. Can't find any gaps under the edge of fence anywhere - were they flying over it? We found a third hen dead on the outside of the fence, so we tried clipping their wings. They are still getting out. Any ideas? Our fence is 4' high. I hate to keep them totally cooped, but hate losing them even more.