Thanks all!
Yes, Crows and Ravens will swarm hawks as do Blue Jays. If you learn their language, you will know there is a hawk present. So many times when I am inside the house here and the chickens are outside, I will hear the Ravens using their "Hawk!" calls and sure enough there is a hawk circling nearby. I am sure they have unknowingly saved my flock on many occasions.
Yes, Crows and Ravens will swarm hawks as do Blue Jays. If you learn their language, you will know there is a hawk present. So many times when I am inside the house here and the chickens are outside, I will hear the Ravens using their "Hawk!" calls and sure enough there is a hawk circling nearby. I am sure they have unknowingly saved my flock on many occasions.