New Caledonian crows, Corvus moneduloides , can come to understand how to solve certain problems more or less like a child between the ages of five and seven would. A group of researchers coordinated by Sarah Jelbert, from the University of Auckland, in New Zealand, collects the conclusions of a trial carried out with these animals in the journal PLoS ONE .
Humans have developed advanced cognitive skills that allow us to understand the causal relationships between different actions. However, it is not clear to what extent other animals display this ability. To evaluate the behavior of the New Caledonian crows , the scientists proposed an experiment that follows the so-called Aesop’s dilemma. In it, it is necessary to drop stones into containers with water so that the level of this rises and obtain an object that is inside the container, but out of reach of the subject. These corvids, which in previous tests have already demonstrated their acumen and capacity for innovation, are among the few species that know how to make and use tools to achieve their objectives, such as sticks or hooks.
After a short learning period, several wild specimens were able to recover the object that had been deposited in the containers in four of the six tests to which they were subjected. Thus, they were able to discern that they could achieve this if the tanks were full of water, but not sand, and that the stones they used to raise the water level were only useful if they sank and were totally solid (they rejected others specially prepared so that floated or included cavities). However, they did not know how to deal with a test in which the thickness of the container had to be taken into account and with another in which the container was U-shaped, a problem that apparently violated normal causal rules. According to the authors, the results show that these crows have a capacity for discernment, at least on these types of issues, similar to that of a child between 5 and 7 years old .
