The interesting thing I learned about birds is that they have more efficient brains, pound for pound, than mammals. It's not just about brain-size-to-total-mass

The interesting thing I learned about birds is that they have more efficient brains, pound for pound, than mammals. It's not just about brain-size-to-total-mass ratio, it's also an absolute how-much-processing-power-does-this-brain-mass-get-me ratio. This almost assuredly would have been driven by the constraints demanded by the need for flight. Crows can use tools just like primates, with far, far smaller absolute brain weights.