鸟粪一种主要由海鸟或蝙蝠的排泄物构成的物质，在某些海岸或山洞中不断积累，用做肥料 A substance composed chiefly of the dung of sea birds or bats, accumulated along certain coastal areas or in caves and used as fertilizer.
海鸟每年都要从一个地方迁徙到另一个地方。 Seabirds will fly from here to another place for migration every year.
