one in five of all mammal species is a bat. 所有哺乳动物中有五分之一是蝙蝠

256. Flying allows animals to search much further for food...
     飞行使动物能够到更远的地方觅食
257. and gather in their millions.
     并且可以成千上万只聚在一起
258. Today,
     如今
259. one in five of all mammal species is a bat.
     所有哺乳动物中有五分之一是蝙蝠
260. But bats were not the first animals to take to the skies.
     但蝙蝠并不是第一个上天的动物
261. Having spent the night foraging,
     经过了整夜的觅食
262. these fruit bats are in a race to return to the roost...
     这些果蝠竞相返回巢穴

来自《我们星球上的生命 第一季 第七集 Life on Our Planet S01E07 地球继承者》第 259 行