Crows roost communally. Crows can describe individual humans and inform other crows in their community about threats and friends. Corvids are highly intelligent and very social. Birds are dinosaurs.
Part of the fun of feeding crows is realizing that, as a direct result, real live dinosaurs are going to talk to each other about you personally.
@kistaro I got to see a murder of crows last night as they gathered together to roost, easily fifty-plus individuals. I could tell they were watching me, and warning each other about my presence, as I gave them a wide berth to watch their behavior.
I didn't have anything to feed them at the time, unfortunately. Would've been nice to demonstrate to the entire group at once that I'm a potential food source instead of a threat, since I wear a hat full of unique shinies they can easily learn to ID.