What about the crows eating chicks/ducklings? I would imagine if you fed them enough, they would have no interest!
What about diseases carried by crows? Are they of concern for a flock?
I think if you keep your chicks protected for a couple of months it will be no problem, they don't carry things off with their talons like hawks or owls do, they use their beaks to haul stuff away. I know they will steal and eat eggs if they get the chance.
The crows we have around here don't hang around the areas that our chickens forage in, they mostly stick to the trees and up on the hills that we have nearby. They will come in and eat cat food or bread or whatever we throw out there, but I try to keep that a little ways away from where we actually have our chickens. I don't know what the diseases are that might be carried by crows either, other than west nile virus. I'm sure they do have other diseases or parasites or whatever, but I think the benefits outweigh any potential problems.