How do birds fly in a seemingly straight line instead of up and down when they flap their wings?

Question

How do birds fly in a seemingly straight line instead of up and down when they flap their wings?

In: Other

Answer 1

Woodpeckers display the undulating flight you’re describing. They alternate a burst of wing flaps that makes them rise, followed by a gentle bound downward with their wings tucked in close to their bodies.