I place shiny things over & around my runs. Children's foil pinwheels up on top of the fence posts, sun catchers and old CDs & DVDs hung on strings over it. I drill a hole a little off-center on the media so the discs hang somewhat horizontally & reflect the light back up into the sky.
I've mostly had red-shouldered hawks here, and they seem mostly attracted to chicks and lame adults. They've come to the ground & pecked at chicks through the wire of their cage. There was one that killed a small mama hen who must have been defending her chicks, I found the hawk on the ground eating the head off the hen. Poor Quiche! And once a small kestrel killed a chick, I found it eating the chick still on the ground.
Other than that, when the flock is free-ranging in or out of their runs, I haven't had any hawks swooping in. They're often hovering over, and the roos give their growl-word for "hawk!" and everyone freezes & heads for cover. The roos have me trained too, because as soon as I hear that word I too stop in my tracks and scan the sky.
Sometimes the hawks do perch on a nearby tree and survey the chickens, then they really start to squawk! We all run out from the house and clap & shout to scare off the hawk.
There are lots of ospreys around here, has anyone ever lost a chicken to an osprey? I know they catch live fish, will they eat a chicken?
Yesterday I saw a bald eagle flying across the sky over our house, close enough to positively ID him. It was my first sight of one in the wild, it was impressive. I was in the car on my way home, so I didn't hear what the roos & the other chickens had to say about that eagle. Will they swoop in & catch a chicken?