Because of the number of predators in our area, I lock my turkeys up at night in a very secure coop. During the day they have access to a 24' x 24' pen that can be divided into two 12' x 24' areas. I'd like to keep the pens covered to prevent them from flying out but have had little (or no) luck with the lightweight bird netting. If you cover your runs, what do you use? TIA!