But the terror bird moves in near silence. 但是骇鸟的行动悄无声息
But becoming small wouldn't work in every part of the planet. 但变小并不适用于地球的每一个地方
but their tiny cousins had recolonized them 但它们的小表弟以一种全新的方式
But one species of hummingbird has no need to battle. 但有一种蜂鸟不需要战斗
But all this activity comes with a huge thirst for energy. 但所有这些活动都需要大量的能量
But just five million years after the asteroid, 但是在小行星撞击之后仅500万年
But thanks to their ability to survive the cold, 但由于能够适应寒冷环境