Why do ducklings swim in a line?
Wave-riding and wave-passing by ducklings in formation swimming
Ducklings swimming in a line behind their mother are surfing her waves, which saves them a lot of energy.
Ig Nobel 2022
Engineers who usually study ships built a computer model of a mother duck and her ducklings swimming in single file, and calculated the waves around each little body.
A duckling in just the right spot behind its mum gets pushed forward by her wake, and the ducklings behind pass the benefit down the line. It is basically a fluffy, very well-organised surfing club.
Ducklings in a row: adorable and hydrodynamically efficient.