I think the fishing line webbing is a good idea. Hawks like to swoop in, they usually don't dive straight down and anything that prevents them from getting a nice long run at the chickens will help. They can also come in and perch in the trees and dive from there. But I think the fishing line can still be a deterrent there. And anything that will delay the hawk before he gets to the ground gives the chickens that much more time to get under cover. Another thing you can do if you have some spare pallets is either lean two up against each other like an A-frame, or add some legs to get them off the ground. Then set them out in your open areas. It gives the chickens cover to run under. That is what I have done in my run.