Try hanging some of the CDs high in a tree, maybe 15 to 20 feet up. I have had no hawk problems since doing that. Umbrellas sound like a good idea, have heard of concrete blocks with pallets on top to make hides for your chickens. My girls use the fence to run along when scared, plus we have lots of bushes and trees. Watch the attacks and place CDs in flight path. If no trees get some long cane polls and attach CDs.
I have 20 CD's around coop
I have 20 CD's around coop