Small birds molt once or twice a year, and they replace their 9 or 10 primary flight feathers a few at a time over the course of a few weeks.

• 小型鸟类一年进行一到两次换羽，在换羽期间，它们一次会替换掉9到10根左右的飞羽，而这个过程将持续几周时间。