i was once eating at a fast food joint, and whatched a crow drop a walnut or pecan while flying fairly high , trying to crack its shell.
After the 2 try it dropped the nut in the drive thru lane, and waited on a light pole for a car to drive over it.
It tokk on a couple or three cars before one drove over it and broke the shell.
The crow then flew right after the car and got his prize.

black birds are considered to be a bad omen, time to break out the AK47