And humans don't? Sure they're not on our level of intelligence, but I think that is due to the fact that they don't have hands like us. Take away your voice and your arms and you will look as intelligent as one of those crows when you get hungry. And why does it take a large brain to be considered smart? Look at computers, getting smarter and smaller all at once. You'd think an animal that can fly would need to maintain its lightweight, so in order to develop its intelligence over time, it would become smarter without increasing in size.