A hungry enough predator can get through many average defenses via digging under, tearing holes in wire you wouldn't think they could, etc. I designed and built my coop and it is predator PROOF! My chicken door locks up and down super tight utilizing ceramic hard drive magnets, and the main door is solid, 2" thick and bolts tight at night, as well as using the same type HDD magnets to keep it tight during the day as I clean, check for eggs, etc. It's nice when your hands are full and all you have to do is lean on the door to open it, then push it with your foot to close it back to the magnet! The windows at each end have woven wire coverings that a bear would have a hard time trying to get through, and the 7x4 foot picture window is 1/2" thick tempered glass! The walls are double thick, 1/2" plywood. Plastic covered plywood floor on 6" ground exposure PTL for the foundation. And believe it or not, a plastic roof! (on top of the plywood, of course) A good, solid coop design is very necessary in some areas, not so important in others where predators are scarce. Location, location, location!