"When geese fly in a 'Y' shape", it describes a classic scene of geese migrating: geese fly from afar, sometimes forming a "Y" shape and sometimes a "1" shape. Why do geese fly in this way? Are they born calligraphers?
Regarding why geese fly in such formations, the most famous explanation is "energy conservation". The "energy conservation" hypothesis was first proposed by German aerodynamicist Karl Wieselberg. Through simple calculations, he found that when geese flap their wings, a vortex will form behind them. The vortex on the outside is upward, and if other geese on the edge happen to be in the vortex, they can save energy. This hypothesis has been verified by observation. Small migratory birds often fly in groups, while larger geese and swans choose to fly in formations because their body weight is much heavier.
However, there are still doubts. Many researchers believe that Wieselberg's model is too simplistic. Even the modified model only considers static situations. The actual flight of geese is much more complex. Current animal experiments also cannot fully prove how much energy can be saved by such formation flying. However, its other benefits are obvious: geese's eyes are located on both sides of their heads, providing a 270° field of vision. This way of flying can at least ensure that every bird in the formation can see other birds and make better adjustments during flight.