I have lost many birds (and rabbits!) to owls, dogs, opposums, and racoons. It seems whatever I put outside is considered a buffet by the local wildlife. So I finally built something that seems to keep them out. Here it is during constructon: Its roughly 50' x 50'. Its 6' high chicken wire nailed to fence posts and 2x4s at the top and bottom. There is 3' of chicken wire buried around the perimeter to deter the diggers. In this pic you can see that there is 3 strands of electric fencing along the bottom of the run. I got flight netting and covered the top of the run. We put a tall 4x4 post in the center and ran ropes to the corners to hold the net up. You can also see in the pic that there is another strand of electric wire around the top of the fence. The entrance to the coop and run is through a storage building. It works like a sally port in that you have to go through two sets of doors before your into the chicken area. You cant see it in this pic (the pic is older) but the underground wire also wraps around the entire building. I have several wire pens raised off ground. They all sit inside the run. This protects them from predators and the chickens and ducks eat any spilled feed and stir the litter. Finally, since is on the other side of a canal from the house, we finally built a bridge so I don't get wet when feeding the critters. After finishing this project, I have not lost a single animal.