CrowdScience - How do you identify an optimistic crow? - ³ÉÈË¿ìÊÖ Sounds

CrowdScience - How do you identify an optimistic crow? - ³ÉÈË¿ìÊÖ Sounds
How do you identify an optimistic crow?
Do crows enjoy solving puzzles? Biologist Cody McCoy devised an experiment to find out