Interesting. I'm curious to know whether the rooks improved in their abilities to use and craft "tools" as they encountered subsequent experiments, or whether their performance remained roughly constant.<p>The rook seems very hesitant in the first experiments shown, but in the last two videos, it seemed much more confident. One possible reason for the lack of hesitation in the "metatool" experiment is that the rook seemed to watch closely as the scientist set up the trapdoors, and might have been already formulating a plan ahead of time.<p>I think that if that's the case, then the rook has a pretty high level of sophistication -- more than if it was just using trial-and-error to figure out the right combination of stones.