We have 4 Rhode Island Red/Leg Horn crossed girls that are 3 weeks old. (How can they tell the difference at 1 day old?!) We are transforming an old cinder block shed into a coup which is in a fenced in yard. The fence is probably about 3 feet high. Is it realistic for me to think they will stay in this area? We live on an acre. Should their wings be trimmed if they decide to explore? We don't have predators except for owls, but they will be in their coup at night. also, I don't have access to wood shavings for th ecoup floor but do have saw dust. Will that work? Is it unhealthy? Any other suggested materials?