I haven't had trouble with crows either, and as much as I can't stand their sound, it's true that they help warn of trouble. The last two times a fox was creeping around, we were alerted by the crows. What a funny story tho!
Mine love to chase tweety birds (sparrows, finches, etc) from their yard. When they (hens) are on free run, they chase the squirrels, cats, birds, whatever they think is interesting. I think my poor little roo is going to have a nerveous break down just watching all 13 girls.