Crows will harass hawks and mockingbirds will harass crows. There is a crows nest within site high up on an old dead oak tree. I routinely see the 2 crows crackling and dive bombing a red tail hawk that gets too close to it. Fine with me. On the other hand when the crows come near my yard, the mockingbirds will nip at the crows and run them off back to their nest. Again fine with me.