I agree with Allsfair. I've had 2 hawk attacks, and they were similar to your description. Feathers everywhere, but the chicken alive and hiding. The first time, she was still in my yard; the second time, she was 3 yards away. Hawks think they can take an adult chicken, but I think it proves too much for them to carry, so they drop it. Make sure your birds have cover they can run under quickly and easily. I've also found that in my yard, hawks tend to attack from the same angle and place, so I cluttered up that line to break up their flight in.