Have used three things to keep hawks out of the chickens, orchard netting we can get it in 14x100 foot rolls, I use tree stakes every 13 feet, and extend the netting across. I also use regular translucent fishing line as well, about 10 lb test as it will flap in a breeze. This works especially well as the string flashes all over and the birds don't know how to get by. I will also hang CD rom discs from the wire as well for extra flash. The third thing and is usually one of the better ones is a pissed off wife with a .22, she got one last year on the wing that was holding onto a chicken. the chicken lived.