Humans are not the only creatures who can plan, scientists found out years ago. Recent studies showed that great apes have similar capabilities. Now, researchers in Sweden were surprised to discover that the same is true for an unlikely species: ravens.
Ravens, and other members of the corvid family, are known to be smart. Can Kabadayi, a cognitive zoologist from Lund University, and co-author Mathias Osvath, set up a series of experiments to determine if ravens could deliberately prepare for future events, NPR reports. They concluded,
It is conservative to conclude that ravens perform similarly to great apes and young children.
The researchers wanted to see if five ravens could plan while doing tasks that they don’t normally do in the wild, specifically using tools and bartering. Similar studies were done on great apes.
Kabadayi and Osvath trained the ravens to use a rock as a simple tool to open a box containing a treat, if the birds dropped the rock through a small tube. Then they tested if the ravens could pick the correct tool out from among other objects such as a wheel, a ball, a metal pipe, and a toy car, then save it to use later.
In one version of the experiment, there was a delay of 15 minutes between selecting a tool and being presented with the box. The ravens succeeded 86% of the time. In the second experiment, the gap was extended to 17 hours, and the success rate increased to 88%.
The ravens were also trained to use a specific item to barter with a human for a food treat. Then a different person offered the birds a tray with the token on it, along with other objects mixed in. “When the ravens knew that trading would only happen on the next day, they chose and stored these tokens as soon as they were offered to them,” observed Markus Boeckle and Nicola S. Clayton, who wrote a separate paper on the study.
The researchers found that the ravens would not choose immediate food rewards when there was a promise of larger, more delicious treats later on. The birds were also more likely to suffer through delayed gratification if they only had to wait a few seconds, rather than minutes for a bigger treat. Kabadayi said, “We basically found that the further ahead in the future a reward for ravens, the less value it gets.”
These planning skills likely developed and evolved through convergent evolution, Kabadayi said. There are many different theories why ravens would have learned to plan ahead, including their complex social hierarchy and environmental factors.
The study was published in the journal Science.