#Crows are some of the smartest creatures in the animal kingdom. They are capable of making rule-guided decisions and of creating and using tools. They also appear to show an innate sense of what numbers are. Researchers now report that these clever birds are able to understand recursion—the process of embedding structures in other, similar structures—which was long thought to be a uniquely human ability.

https://www.scientificamerican.com/article/crows-perform-yet-another-skill-once-thought-distinctively-human/