crows are very smart, though some farmers apparently aren't fond of them for whatever reason. I remember when I was small game hunting and the farmer indicated that shooting crows on his property was OK by him. In the afternoon the fields were quiet so a couple times we were thinking if the crows come overhead next time we'll shoot a couple of them; this is after they had been flying over us all morning. As soon as we thought this, they stopped flying over us! I believe this inspired Alfred Hitchcock