Crows are smart, but not THAT smart.
When I was a punk kid I used to shoot them with a pellet gun when they'd land in the vacant tree-filled lot behind my house. If they could see me, they'd fly away as soon as I appeared but if I could remain hidden they wouldn't fly away even after several of their number had been dropped. One would fall and the rest would go crazy, flying around in circles and cawing like mad but eventually they'd start landing in the trees again and then another would fall and they'd repeat the behavior. You'd think they'd realize that staying in that area was a bad idea as their buddies were dropping dead, but they'd stay as long as they couldn't see what was causing the problem. Furthermore, they'd return to that group of trees regularly rather than avoid it.
Yes, I feel bad about that now. Just bringing it up as an example of strange behavior that seems to run counter to other observed behavior and their learning abilities.