One common misconception people have regarding evolution is that the gradual changing of physical forms always benefits the species in question.
It's not just the size of a brain that determines intelligence, it's also the amount of neurons.
Why do some species of birds-of-paradise have such eye-catching plumage?
If you load a plane that can hold up to 2,000 pounds with more than 2,000 pounds of birds, will it still be able to take off?
Do birds have teeth? Not anymore, but they once did, when they were more similar to dinosaurs.
During migration, birds' digestive system partially shuts down to conserve energy for flight.
Birds use infrasounds to sense storms long before dark clouds gather.
Birds and many reptiles evolved a specialized way of breathing—one-way air flow.
Birds of a feather steal together (and suspiciously hide food from one another).