@markwyner Yes, this puzzle is beyond most 3 and 4 year-old humans.

I'm old. "Birdbrain" used to be a common insult. Not anymore.

The problem, as usual, is ignorance. We used to measure relative intelligence in terms of brain mass. More brain mass == smarter. But it turns out that brain mass is a poor metric.

There's more than one way to design a brain. In large animals like humans, the design rules are more relaxed. In birds that fly, it's obviously important to keep brain size and mass to a minimum, so the design rules are different. And yes, you can build a brain that's much lighter and more compact than a mammalian brain if that's what's required.

Brain mass alone doesn't mean shit if the starting design constraints are different. So yeah, corvids are smart. Way smarter than their size implies.