In Aesop’s Fable “The Crow and the Pitcher,” a thirsty crow encounters a pitcher with a little water in it, but is initially thwarted by the low water level and the bottle’s narrow neck. Then the crow starts dropping pebbles into the pitcher, however, eventually raising the water level high enough for it to drink.
Not only has research verified that crows can do this, but it shows they can pass the water-displacement test at a level similar to human children between the ages of 5 and 7. Crows have conquered a variety of other convoluted tests, too.
Crows can also plan their tool use, according to one study in the journal Current Biology, which found crows could solve a metatool problem when each step was out of sight of the others, planning ahead three behaviors into the future. The birds showed an ability to “mentally represent the goals and sub-goals of metatool problems,” the researchers wrote, and even successfully ignored an extra tool that was planted in their path to distract them.