Clever birds

Are birds smarter than we think? If you ever watch birds, especially crows, they appear to be clever critters. I've watched them in parking lots milling among the cars looking for food. Sometimes, they pick dead bugs off the front of cars. Maybe not the most clever thing ever, but easy pickings if you are a bird. Anyway, just saw this article on the www about rooks, or crows, using stones to raise the water level in a bottle so they can get a worm floating on the water. That's cool.