I actually heard about using crows from a naturalist at the wildlife refuge across 35W. He said those owl statue things attract them as well since the crows like to attack them. Unfortunately I have a real pair of great horned owls that live near by and eat all the crows. Plus my dog likes the frozen/reject eggs too muchI have had problems with hawks too. I covered all of my pens but I do let the birds out from different coops and pens on different days. We put a 2' piece of chicken wire around our blueberries to keep the chickens out because they scratch around and blueberries have rather shallow root systems. One day I let the RIW's out into the pasture but one of the girls managed to go over the fence and get into the blueberries and before I could blink there was a hawk. I scared off the hawk but it had already killed her. That hawk kept coming back. We have crows around and when the crows see any hawks they will chase them off, so I started putting any eggs that were cracked that I wasn't going to put out for sale for the crows to eat. I kept putting the eggs in the same spot and went online to listen to crow recordings for a friendly call and when I put the eggs out I started trying to imitate the call. Now the crows hear me and they come to investigate.