There are 9 species of wild geese in the world, including 7 species in China. In addition to white geese, there are also common geese, such as Hongyan, Yan Dou, Bantou Goose, Grey Goose, etc., which are commonly known as geese among the people. The wild goose is one of the well-known birds. When migrating, dozens, hundreds or even thousands of geese always gather together and fly in a line with each other. The ancients called them strict formations. Yan Zhen is led by experienced leading geese. When speeding up the flight, the team lined up in a herringbone. Once it slows down, the line changes from herringbone to a word-long snake. This is an effective measure for long-distance migration. When the wings of the head geese flying in front pass through the air, there will be a weak updraft at the tip of the wing, and the latter can use this airflow in turn, thus saving physical strength.