Birds of prey from above alsoCords are the way to go if you have enough ground and have predators under control. Control likely will mean dogs and a fence. Perimeter fence, possibly with a hot wire or two strongly advised. Delay putting birds on cords until good dogs in places. Fencinging with constant trapping or other predator control measures can be used as well but I suggest keeping lesser value birds around perimeter so they are taken first by probing predators.