Has anyone ever really checked out the big fall/winter roosts to see if the crows are both American and Fish crows. It would be hard to tell except either when they are leaving or when they start returning since its just too loud when the group is beyond a few hundred. I used to work on Executive Blvd in Rockville (10,000 crows over our parking lot), and we often wouldn't leave without umbrellas, the crows were so thick in the trees above us. I sort of miss them. I never bothered to try to see if any fish crows were present though. I don't think seven corners is too far from the Potomac to rule out Fish crows. I see (hear) them in Reston often. Chris Taylor