I raise sheep and was talking on the Sheep-L list to a shepherd out in Colorado. She had an eagle swoop down and snatch a hen. Her guard llama hustled her sheep into the shelter then went after the eagle by rearing up and trying to strike it out of the sky. But the eagle had gained too much altitude with the struggling chicken. So as last resort he spit a wad and hit the eagle in the head. The startled eagle dropped the hen and the eagle got the heck out of there. They had anti-air defenses!
I have had a red tailed hawk try to take a guinea before. He had to pull up because at the last moment he realized that there was a fence line in the way. He sat on the fence looking at the fat guineas so disgusted with himself for missing that point. I have bought a net off of ebay to discourage that with my new chickens. You can suspend it between trees or make supports that suspend it over the areas that you range you chickens. It's main purpose is to prevent aerial attacks not to keep ground predators out of a pen. You can even weave ribbon into the net and turn it into shade cloth. Now I got one of the super cheap ones from China. I will let you know that even though it's dimensions were given as a rectangle it is actually somewhat more like a trapezoid, but it is large enough to serve my purposes and was the right price for my budget.
