nest-building

例句：

1. 1. Birds build their nests in trees to protect their eggs from predators.
   鸟类在树上筑巢以保护它们的蛋免受捕食者的伤害。
2. 2.The bird is busy building its nest for the winter.
   这只鸟正在忙着为冬天建造它的巢。
3. 3. She carefully collects materials for her next nest-building project.
   她仔细收集材料，准备进行下一个筑巢项目。