why do people say "bird brain" ? Birds are smart!

I have a few families of robins living in my yard, and I sometimes hear them as early as 3:00am. It's not so much singing and more of a flock call (one may wake up and chirp to make sure everyone else is still around).

Birds can see more colors than we can (they have cones in their eyes for ultraviolet light), and I've read that some can even see light of dawn before we do.