A novel research shows that a species of crow can solve problems based on an Aesop's fable similarly to that of five to seven-year-old children. Researchers from the University of Auckland carried out experiments on the basis of an Aesop's fable. New Caledonian crows, Corvus moneduloides, have an understanding that by throwing stones in a partially filled tube of water will increase the level of water in it to provide them a reward.

But researchers said that the understanding had its own limits and the study also throws a light on topic called an understanding of cause and effect. Lead researcher Sarah Jelbert from the University of Auckland said this species of crow is the only non-primate species to make tools in wild.

An experiment was designed to test the knowledge of the crows with regard to the cause of water displacement. In this experiment, Aesop's tale example was used in which a crow dying of thirst comes to a jug of water, but its beak could not reach to water and the bird drops pebbles to let the water come to the top of the jug.

The same experiment was replicated in which six wild-crows caught were given a week's training. They were taught that dropping stones into a tube would produce a reward. After training, six tasks were given to them.

Some of the observations made were, the researchers preferred to drop stones into water-filled tube rather than a sand-filled tube. Crows preferred to drop heavier objects than the floating objects. Solid objects were chosen over hollow objects.

Crows were found to drop objects into tube with a high water level than a tube having a low-level of water. "The results show the crows possess a sophisticated understanding of the causal properties of volume displacement, similar to that of five- to seven-year-old children", said Jelbert.

But it was also found that when it came to choosing between wide and narrow tubes and understanding about the level of efforts involved in raising water levels in different tubes, crows did not have any preference. Moreover, they did not get to know that narrow tube needed less stones than the wide tube. Researchers said more work on the matter is needed.