【英语时差8,16】鸟类迁徙与消化系统（上）

If you thought birds were amazing before, wait until you hear what they put their bodies through in order to migrate. Although it’s probably no surprise that migration¹ requires a lot of energy, until recently, ornithologists thought migrating birds got all that energy from eating high-energy foods, like berries, along the way. It turns out that the whole process is much more complex. For one thing, before they begin migrating, birds start eating extra food and gain weight. To enable them to take in more food, their digestive system actually changes–its cells grow larger and produce new cells and their gut² expands dramatically. But here’s the really fascinating thing. As you might expect, digestion³ in birds consumes a lot of energy. In fact, the gut is the fastest growing tissue in the bird’s body, since it’s continually digesting and renewing itself.

1 migration   

n.迁移，移居，（鸟类等的）迁徙

参考例句：

• Swallows begin their migration south in autumn.燕子在秋季开始向南方迁移。
• He described the vernal migration of birds in detail.他详细地描述了鸟的春季移居。

2 gut   

n.[pl.]胆量；内脏；adj.本能的；vt.取出内脏

参考例句：

• It is not always necessary to gut the fish prior to freezing.冷冻鱼之前并不总是需要先把内脏掏空。
• My immediate gut feeling was to refuse.我本能的直接反应是拒绝。

3 digestion   

n.消化，吸收

参考例句：

• This kind of tea acts as an aid to digestion.这种茶可助消化。
• This food is easy of digestion.这食物容易消化。