- Birds have hollow bones that are very light and strong.
- Their feathers are light and the shape of their wings is perfect for catching the air.
- Their lungs are great at getting oxygen and very efficient, so they can fly for very long distances without getting tired.
- They eat lots of high-energy food.
Kim Bostwick, a scientist at the Cornell Lab of Ornithology explains:
“Have you ever tried to move your open palm though the water really fast? Wide, flat objects, like your hand, or a paddle, are hard to move fast against water.” It feels like the water is pushing back against you. Or have you put your hand outside the window while driving in a car and felt the air rush against it? You can see-saw your hand up and down in the wind. In both cases you can feel the water or the air push against the flat palm of your hand. But if you turn your hand sideways, you can slip your hand through the water or air easily, right?”
“When a bird is flying, their wings are flat so that the air flows easily around it in the direction the animal flies (like your hand cutting through the water or air). However, something special and tricky happens here. As the air flows over the wing, the air flows faster over the top than the bottom because the wing is slightly curved on top. This means there will be more air on the bottom side, because the air is moving more slowly. When there is more air on the bottom that leads to a push and since the push happens against that wide flat part of the wing, this push lifts the animal. So a bird wing slices in the air in the forward direction and gets pushed up from below; the net result is a flying bird!”