Why are homing pigeons so picky about their noses?

The main function of homing pigeon nose is ventilation, with long nostrils, large nasal cavity and large ventilation. In ancient China, people often cut the nostrils of young pigeons for better ventilation. This kind of pigeon is good at flying. According to foreign data and homing pigeons introduced in recent years, the nose type tends to be small and medium, and develops to be long, narrow and thin, with the long, narrow and thin nose type being the best. The upper part of the nose is high and well-defined, which is not as good-looking as the one that collapses from the center of the corner of the mouth to the lower corner. Because the former can make the exhaled air flow discharge backward and downward, which is beneficial to flying at high altitude.