... Here in N.E. we have Big Crows and Crows HATE Hawks. If Crows are around the hawks don't play, they go elsewhere so they are not bothered.... I have noticed that [if] Crows have been around... there are no Hawks around that day... So I wondered if you had Black Chickens if the hawks would think they were Crows[?].......
Crows, and ravens too, hate hawks because hawks love crows and ravens, love to eat their young that is. If the conditions are right they are also not above eating the odd adult. To better understand crows pay attention to the ever present Blue Jay. Blue Jays are just mini versions of a crow, even their call is similar if not their coloring. I have seen more Blue Jays with bloody murder on their minds chasing crows than I have seen crows harnessing owls or hawks. All members of the Blue Jay family respond with speed to an alarm call from a member of their own species.
The raven was persecuted hard by our free range chicken owning ancestors. This is no longer the case. Before long chicken stewards will be once more vilifying ravens as the chicken killing beast that they always were.