Are Crows Smarter than a First-Grader?

Crows, while they may look dimwitted, may in fact be resourceful problem solvers and smarter than the average first grader, a new study indicates.

According to a fable by Aesop, the Greek storyteller, a thirsty crow happens upon a pitcher of water but when it tries to drink from the vessel, it cannot reach. So, the bird merely drops pebbles in to the pitcher until the water level rises enough that he can quench his thirst. Well, new research from the University of California, Santa Barbara suggests that the birds' intellectual prowess may be more fact than fiction.

"We showed that crows can discriminate between different volumes of water and that they can pass a modified test that so far only 7- to 10-year-old children have been able to complete successfully," lead author Corina Logan said in a statement. "We provide the strongest evidence so far that the birds attend to cause-and-effect relationships by choosing options that displace more water."

Logan and her colleagues caught New Caledonian crows from the wild and habituated them to a small set of aviaries (the birds were released back into the wild at the end of the study). In the testing room was an apparatus consisting of two beakers of water, the same height and diameter, but one wide and the other narrow.

The researchers' goal was to see whether the birds could distinguish between water volumes, and if they understood that dropping a stone into a narrow tube would raise the water level more.

"When we gave them only four objects, they could succeed only in one tube - the narrower one, because the water level would never get high enough in the wider tube; they were dropping all or most of the objects into the functional tube and getting the food reward," Logan explained.

"It wasn't just that they preferred this tube, they appeared to know it was more functional."

But the cognitive mechanism behind the correct choice has yet to be seen, and researchers agree that more work is needed.

In another part of the experiment, crows as well as children ages 4-10 had to choose between two sets of tubes. With one set, when subjects dropped a stone into a wide tube, the water level raised in an adjacent narrow tube that contained food.

Participants age 7-10 completed the task with ease, but apparently this was a challenging concept for both crows and children, particularly those ages 4 to 6. However, once researchers widen the gap between tubes, the younger children finally figured it out - although most crows still did not.

"What we do know is that one crow behaved like the older children, which allows us to explore how they solve this task in future experiments," Logan said.

The findings were published July 23 in the journal PLOS ONE.