I have recently introduced my former coop-and-run chickens to a large fenced in area. They were doing nicely until I found one outside the enclosure. This has kept happening, and I have tried several attempts to solve it. I lowered the fence's lower clearance and clipped the chickens' wings. It has not helped. Two hens have already been lost to this. What can I do to stop them from escaping? The fence is completely holeless and is four feet tall (once again, the chickens are clipped.); its lower clearance ranges from one to two inches off the ground. Also, there are no large objects for them to launch off of inside the area besides the nine foot tall coop.