这种鸟边飞边睡觉

军舰鸟可以飞很多天。它飞过辽阔的大海。它不能停在水面上。那么它什么时候睡觉呢?

A frigatebird can fly for many days. It flies over the open sea. It cannot land on the water. So when does it sleep?

科学家在军舰鸟身上装了小机器。这些鸟能连续飞十天。它们边飞边睡觉。一半大脑睡觉,一半大脑醒着。一只眼睛睁着。

Scientists put small machines on the birds. The birds fly for up to ten days. They sleep while they fly. Half the brain sleeps. One eye stays open.

这很让人吃惊。在海上,军舰鸟一天只睡四十分钟。在陆地上,它们睡十二个多小时。它们在家的时候休息很多。

This is surprising. At sea, birds sleep only forty minutes a day. On land, they sleep more than twelve hours. They rest a lot at home.