Birds flap their wings while landing even though it costs energy, new model explains why

In the mobile game Flappy Bird, the bird’s problem is not flying forward, it is staying airborne. Every tap buys a little lift, every pause lets gravity pull it down.

Real birds face a harder version of that challenge when they land. They must shed speed, remain controllable, and arrive safely on a branch, ledge, or patch of ground.

New physics research, published inProceedings of the Royal Society A, suggests that the wing-flapping birds do during landing is not wasted energy, but a practical solution to a difficult aerodynamic problem.The paradox of landingFlying expenses a lot of energy, and flapping costs more energy than gliding. So it seems logical that a bird approaching a perch should stop flapping, glide in, and touch down as slowly as possible.