蝙蝠有900多个不同的种类，遍及世界各地。尽管它们看上去很像鸟类，但它们没有羽毛，也不生蛋。它们是哺乳动物：雌性产下幼仔，用乳汁哺育。
某些种类的蝙蝠是飞行高手，它们能够在狭窄的地方非常敏捷地转身，蝙蝠是惟一能振翅飞翔的哺乳动物，其他像鼯鼠等能飞行的哺乳动物，只是靠翼形皮膜在空中滑行。
夜间，蝙蝠靠声波探路和捕食。它们发出人类听不见的声波。当这声波遇到物体时，会像回声一样返回来，由此蝙蝠就能辨别出这个物体是移动的还是静止的，以及离它有多远。
蝙蝠什么都吃，包括果实、鱼类、花粉，甚至血。大部分蝙蝠在夜间飞行时捕食昆虫。每只蝙蝠都能辨别出自己发出的声波，这说明即使与其他蝙蝠一起捕食，它也不会被别的声波所干扰。
It is nearly dark.From out of a cave，a black cloud swirls.Suddenly you realize that it is made up of thousands of bats.
Does this make you think of Halloween，or movies about Dracula？People often fear bats as “creatures of the night.”Yet these remarkable animals are helpful to us.They eat insect pests.They pollinate useful plants，as bees do.Their droppings，called guano，are used as fertilizer.
Bats are the only mammals that can fly.They are usually active at night.This Kitti’s hog nosed bat，also called the bumblebee bat，is the smallest mammal.It’s about an inch long！
Bats are the only flying mammal.A bat’s wings are supported by bones like those in your hand.Each wing has a clawed thumb that the bat uses for clinging to trees，cave walls，or buildings.
What Is a Bat？