moulting

例句：

1. 1. The bird is in its moulting stage, and it will not be able to fly for a few weeks.
   这只鸟正处于换羽期，在接下来的几周内都无法飞行。
2. 2. During the moulting season, birds are unable to build feathers and must rely on their quills for protection.
   换羽季节，鸟类无法筑巢，必须依靠它们的羽毛来保护自己。
3. 3. The moulting process is essential for the bird's survival as it helps them shed oldfeathers and replace them with new ones.
   换羽过程对于鸟类的生存至关重要，因为它们可以帮助它们摆脱旧的羽毛并换上新的羽毛。