Electrified poultry netting. You can surround a much larger area, for far less $$$ then it would cost to build a wood framed, hardware cloth "run". I have mine up for 4yrs, and no ground based predator has got past it, not a even a snake. I have 650' of it, and I consider it one of the best things I have bought for my birds.
http://www.premier1supplies.com/fencing.php?mode=detail&fence_id=93
http://www.premier1supplies.com/fencing.php?mode=detail&fence_id=93