Crows may be as smart as a seven-year-old child, according to new research.
A recent study was conducted on six crows from New Caledonia, which is a collection of islands approximately 750 miles east of Australia.
Research was published in the online journal PloS One.
The six Corvus moneduloides from the island of Grande-Terre were captured for the experiment. Researchers were inspired by "The Crow and the Pitcher" for the experiment.
In the story, a thirsty crow finds a pitcher of water that is too low in the container for the crow to reach. The bird then starts to drop small stones in pitcher until it is able to reach the water.
The study conducted on the six crows involved a vessel containing a treat and water, according to the study.
A small piece of meat was put on a floating on a cork and then placed out of reach of the birds. Like the story, the birds placed pebbles into the container to make to raise the water level, thus retrieving the piece of meat.
This test was designed to test crow's ability to understand the basics of fluid dynamics.
"We found that crows preferentially dropped stones into a water-filled tube instead of a sand-filled tube; they dropped sinking objects rather than floating objects; solid objects rather than hollow objects, and they dropped objects into a tube with a high water level rather than a low one," researchers said in the journal.
When choosing between a vessel with water at the bottom and one containing sand, 76 percent of all stones drops were placed in the container filled with water, according to the study. The birds were also given choice between polystyrene (which floats) or rubber "stones" which sinks. Approximately 90 percent of the time, the crows made the correct decision.
Crows failed more advanced tests however, involving tubes of different widths. This suggests the level of understanding the birds possess likely rivals that of children aged between five and seven, according to the study.
Corvus moneduloides is the only non-mammal known to create and use tools in the wild, according to the study. The birds are capable of tearing barbed leaves off twigs and then use them to capture insects.
Sarah Jelbert, from the University of Auckland, led the study.
"Understanding this could in turn help us to piece together the evolution of cognition in our own species," Jelbert said in a statement recently.
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