Hammer,
About the closest I have ever seen was going into the Gander Mountain store in N. Little Rock one evening. My wife and I got out of the truck and she was at the front door looking back at me because crow after crow was flying over the store. I was stopped in the parking lot starting up. A reasonable estimate was there were a couple hundred headed back to their roost from the landfill a few miles down the road.
Yeah, my wife thinks I'm crazy, but all I could think was I wish I could find out where they were roosting and if there was any property a few hundred yards off their flyway I could hunt.