What does the 'vane' of a feather do?

The vane of a feather plays a crucial role in the aerodynamics of flight. It consists of the flattened part of the feather that is made up of barbs, which interlock to create a smooth surface. This smooth surface is essential for reducing drag and allowing for efficient movement through the air. The design and integrity of the vane enable birds to achieve lift and maneuverability while flying.

While other functions might contribute to a feather's overall purpose—such as providing structure, cushioning, or protection—none are as directly linked to the act of flying as the vane. It is specifically the vane that contributes to the feather's ability to function as an aerodynamic surface, which is vital for flight efficiency and performance.