© PLOS ONEIn an experimental recreation of "The Crow and the Pitcher" from Aesop's Fables, scientists found that crows actually do have a sophisticated understanding of water displacement.
Now scientists have evidence to back up that tale. New Caledonian crows actually do understand how to make water displacement work to their advantage, experiments showed. The results suggest that the birds are, at least in some respects, as smart as first-graders, according to the study.
Researchers led by Sarah Jelbert at the University of Auckland in Australia presented six crows with tubes filled with water. Inside the tubes, a worm or chunk of meat on a cork was floating, just out of reach of the crow's beak.
In front of the tubes, the researchers arranged a bunch of heavy rubber erasers that would sink, and light polystyrene objects that would float. In other variations of the experiment, the birds were presented with hollow and solid cubes.
The crows figured out that they could drop the heavy objects and the solid cubes into the tubes in order to raise the water level and get their snack, the researchers reported March 26 in the journal PLOS ONE.
The crows' understanding of water displacement, however, might be incomplete. The birds fumbled in experiments in which they could choose to drop objects in either a wide tube or a narrow tube to retrieve a snack, the researchers said. Dropping objects into the skinnier tube would lift the water level by a greater amount and put the treat within reach after just two drops. In contrast, it took around seven drops to raise the snack to the same level in the wider tube. The crows apparently didn't realize this, and most of the birds went for wider tube first.
Previous studies showed that chimpanzees and human children can solve similar tasks. In a 2011 study detailed in PLOS ONE, apes and kids figured out that they could spit water into a tube to reach a peanut that was floating in a small amount of water at the bottom.
"The ability to detect and respond to relevant causal properties demonstrated here, is striking, in spite of its limits, and rivals that of 5 - 7 year old children," the researchers of the new study wrote.
The results only add to the list of crows' amazing abilities. The birds are known to use tools, making hooks out of sticks to fish ants out of nests. They don't forget a face, and they hold grudges against humans they perceive as threatening.
Reader Comments
to our Newsletter