I think I'm getting ready to build a "fort!" If you're already seeing that many hawks around, then I'd watch after putting the chickens out. I'm sure they'll be thrilled with the new smorgasbord! I like hawks & I think they're beautiful birds...until they kill my chickens!!! They will carry off the small dogs too, so I don't blame you for watching your dog. I've heard that the crows will supposedly keep the hawks away (I can see why after reading your story) but I'm not sure if they do or not. At least the crows don't eat chickens! Good luck & let us know how it goes!
Crows can be a big help if your property is part of their home range. They should be considered part of an early warning system, but they aren't always around, and should only be part of your anti-hawk defenses. Be aware that crows can and will eat baby chicks-- but so do MANY other animals, even blue jays and squirrels, so it's always best to protect baby and young birds anyhow. I've found crows to be helpful.