Travelling storks
Youtube-Video
GPS data visualization of 27 stork travelling between two thermals from the point of view of a follower. The flight path of each bird is color-coded based on its overall flapping activity from blue (low) to orange (high). Followers benefit from the thermal exploration of the leaders ahead, but spend more time in energetically costly flapping flight to keep up with the flock.
https://www.youtube.com/watch?v=kwPT-MsWQUI