Crow birds are generally known to be clever like parrots too. They have big brains. I recently red from a finnish nature magasin about this subject. They say that you hardly can talk the cleverness of birds same way as human beings. There are genotypes, experiences, behavior patterns, sense of hearing or seeing e.g. that have effect on the thing also birds who have small brains.

In the winter crows go to the ice to get fish from jiggers. If a jigger has left his jig to the ice hole to do something else, the crow pulls the line with the bait up.