Crows have long been considered one of the most intelligent species of birds, and a new study supports this theory, finding that birds have an understanding of causal reasoning similar to that of a five to seven year old child.
In a stud published in PLoS ONE, Sarah Jelbert et al tested the intelligence of New Caledonian crows in a series of tests related to water displacement using what is know as the Aesop’s fable paradigm – “in which subjects drop stones into water to raise the water level and obtain an out of reach reward”.
In one test, the six crows needed to work out that if they dropped stones into a pitcher, the water level would rise, letting them drink from a narrow container. Not only did the crows complete the test, but they worked out that they were best off if they chose pitchers with higher water levels, and to chose solid rather than hollow stones.
The crows were less successful in another test, however, with a U-shaped container and hidden connections to a number of pipes, as the researchers found on this test that the crows “showed no signs of learning which tube would bring the reward within reach over the course of the experiment” and even performed “worse in later trials”.
The scientists concluded:
“Overall, the results of our six experiments suggest that NC crows do possess a causal understanding of displacement, but this understanding has limits…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”
