I recently read an article on this very topic. I don't think there is much distinction between brain size or actual intelligence, but smartness? Maybe that word could mean something different. read more
When problem solving exercises were presented to crows and keas, the crows were always better at tool use, because they have the beak for it. But the keas, despite their curved beak, tended to solve the problems more quickly, because of their incessant curiosity, improvisation and willingness to try new and different things. read more