Actually, it is that the predators see your yard as a free and easy buffet. I'm not saying this to insult you, just try to look at it from the predators perspective. See, if you are a predator and the hunting in one area is good, you will keep coming back to that spot until you have hunted the prey out of the area. (People do the same thing, returning to good hunting grounds) So, if the hawk comes once and eats your chicken, then comes back a week later, and sees the chickens and is able to get another on, he will continue until there is nothing left. So, what happened is that for 7 yrs, no predators had discovered how great of a "hunting" ground your yard is. Once they discovered it, they continued to hunt there. As long as the food source is there and easy to exploit, it is natural that they would continue to kill your birds from that point on. What you need to do is to create the impression that the area is "hunted out". This will take time and vigilance. Keep your birds penned up. Do this until the raptors move on and come by less and less. It will work for the most part, although the predators will probably always remember that they had a lot of success in your yard, and will check back periodically. That's where your vigilance has to set in, when you do start back to free ranging, you will always have to be on guard, and shut up your birds when u can't be focused on their safety.
