Science Magazine has an article detailing an experiment with a female New Caledonian crow where the bird, in order to retrieve food from a vial, fashioned a hook out of wire to use as a tool. The food was in a small bucket which the crow lifted up using the wire tool. This is quite amazing, considering that although chimpanzees, thought to be our most intelligent primate cousins, have been known to use tools, they have never been known to construct them. Even more amazing is this video documenting the action.
Also curious is that the female formed the hook after a male crow, also in the experiment, stole a previous man-made hook from her. Once the female retrieved the food, the male would then steal it from her. This begs the question of which of the two crows is more intelligent: the female who crafts a wire hook to retrieve the food, or the male, knowing that the female will go to the trouble of obtaining the food, uses a strategy where he waits and then steals the food once it has been obtained.