I LOVE "my" crows -- they don't bother the bantams or the chickens, but they will gang up on a hawk in flight, pick it, harry it, attack it until it leaves the area. If it weren't for "my" crows, I'd probably have fewer chickens.
The only time crows are a danger is with tiny chicks However watching the mother banty teach the crow what a really bad idea that is can really be entertaining!