Evolution towards flightlessness has been much more common through history than scientists once thought.
Geese honk loudly and point their bills toward the sky when they're ready to start the migration. Here's how they know it's time, how they navigate and how they conserve energy on the grueling trip.
Did feathers evolve in the common ancestor of pterosaurs and dinosaurs? Not everyone is convinced
Inspired by the aerobatic manoeuvres of the swift, a new "flapping wing" aircraft can hover, glide and dive much better than quadcopter-style drones.
One bird we tagged flew for 172km without a single flap.