Proving that crows are intelligent enough to recognize behaviour that is "personally rewarding," and have sufficient communication skills - or the ability to steal methodology from others - for the knowledge to be passed on to others of their ilk.

Obviously, crows have at least the same level of intelligence as a moderately successful politician.

(Anyone who's watched crows in the wild much will not be too surprised at this, although it's at the "top end" of what I've seen them do.)

John