New Caledonian crows are notoriously brainy. Now researchers have demonstrated that these crows (Corvus moneduloides) make sophisticated inferences by observing the world around them.
A team that included Rachel Miller at the University of Cambridge, UK, trained one group of crows to fetch heavy objects in exchange for a bit of meat; other birds were taught to bring light objects to earn the reward. The researchers then suspended unfamiliar objects from strings in front of a fan, allowing the birds to see whether the items either were blown about or remained still.
The birds immediately selected the correct type of object to receive their reward in 73% of the trials — significantly higher than chance. Birds that did not see the wind’s effect on objects made the right choice 48% of the time — no better than chance. The clever setup proves both that New Caledonian crows are good at learning about objects through observation and that humans are not too shabby at designing experiments.