A minimal wake-vortex model explains how a bird following behind and to the side of another can reduce the mechanical power needed for flight by about 11 percent. The leading bird’s oscillating wake reduces the follower’s need to generate thrust, allowing it to flap through a much smaller vertical range. The work converts formation flight from a broad observation into a specific local interaction: position relative to one neighbour changes the energy required by the following agent.
https://phys.org/news/2026-07-birds-flying-formation-energy-flatter.html
