Why do birds fly?
Compared to flying, Archaeopteryx preferred hopping on the ground—birds took thousands of years to conquer the sky. Key conditions for this included their lightweight bodies and, unique to birds, feathers. Explorers and adventurers have made numerous attempts to mimic birds’ flight feathers to fly like them, but they all failed. The main reason is that humans can’t generate the necessary energy for wing-flapping to stay aloft. Birds, however, have strong chest muscles and energy conversion systems that perfectly support the immense demands of flight.
How do birds move in the air?
Birds’ wing flapping might seem like simple up-and-down movements, but different parts of the wing serve various functions during flight. The inner half of the wing, close to the body, has a small range of motion but provides most of the lift. The outer wing forms a large arc and primarily generates forward thrust. When the wings move upward, the outer flight feathers spread apart, allowing air to pass through the gaps, and the wings bend at the elbows to reduce resistance. During the downward stroke, the wings spread out, closing the gaps between the primary and secondary feathers, increasing the wing’s surface area and pressure, which helps produce backward thrust and upward lift.
Energy-saving flight modes
If birds constantly flapped their wings, especially larger birds, they would quickly become exhausted. There are two ways to save energy: first, by spreading their wings and gliding; second, by folding their wings and darting like an arrow. Gliding is slow and allows for rest, making it suitable for large birds. To overcome air resistance, a certain weight is needed because they not only descend but also glide forward. Humans can do this too! Hang gliders utilize wing-like structures to glide slowly. Birds also descend while gliding, which is why they have to flap their wings again. The second energy-saving mode is more common in small-winged birds and during high-speed flight.
