英语听力：自然百科 地球力场 Earth's Force Field—17

 “We drive them about 20 miles away to the North, and release them, and we track them as they try to fly back home.”

 

“We drive them about 20 miles away to the North, and release them, and we track them as they try to fly back home.”

 

 

 

He’s up, OK.

 

 

 

Holland wants to see how the magnetic poles will affect their ability to navigate¹ home. Bats normally fly back to the barn in around 60 minutes, but what happens to those whose senses have been manipulated.

 

 

 

“Now, that's it, he's gone, he's gone. He's gone and he's headed North, so this guy he's had his polarity reversed, his magnetic compass will screw that he's gonna in the wrong direction, but eventually he'll correct it and will get back to the home route.

 

 

 

It takes the bat several hours to make it back, Holland believes that bats/ sense Earth's magnetic field lines, so when the magnetic field reverses, it’s as if they’re navigating² with an upside down map, inevitably³ they go the wrong way.

 

 

 

There is very clear behavioral evidence that animals use the magnetic field for a compass, certainly, and also possibly as a map.”

 

 

 

But fluctuations⁴ in the magnetic polarity/ don't just affect bats. For decades whale beaching has mystified scientists.  But in the 1980s, biologists noticed a correlation⁵ between the location of whale strandings and sudden magnetic anomalies on the seafloor. A weakening magnetic field could cause the leader of whale pod to misread its internal GPS, leading others into dangerously shallow water. 

 

 

 

“There is the potential for this to affect animals’ ability to locate their position using the magnetic field. The Earth's magnetic field is a mechanism⁶ of locating their position. It has just been vital for animals throughout the history of life on earth, and so it's hard to imagine life without the magnetic field.”

 

 

 

An absence of the magnetic poles could be disastrous⁷ for many species including us.

1 navigate   

v.航行，飞行；导航，领航

参考例句：

• He was the first man to navigate the Atlantic by air.他是第一个飞越大西洋的人。
• Such boats can navigate on the Nile.这种船可以在尼罗河上航行。

2 navigating   

v.给（船舶、飞机等）引航，导航( navigate的现在分词 )；（从海上、空中等）横越；横渡；飞跃

参考例句：

• These can also be very useful when navigating time-based documents, such as video and audio. 它对于和时间有关的文档非常有用，比如视频和音频文档。 来自About Face 3交互设计精髓
• Vehicles slowed to a crawl on city roads, navigating slushy snow. 汽车在市区路上行驶缓慢，穿越泥泞的雪地。 来自互联网

3 inevitably   

adv.不可避免地；必然发生地

参考例句：

• In the way you go on,you are inevitably coming apart.照你们这样下去，毫无疑问是会散伙的。
• Technological changes will inevitably lead to unemployment.技术变革必然会导致失业。

4 fluctuations   

波动，涨落，起伏( fluctuation的名词复数 )

参考例句：

• He showed the price fluctuations in a statistical table. 他用统计表显示价格的波动。
• There were so many unpredictable fluctuations on the Stock Exchange. 股票市场瞬息万变。

5 correlation   

n.相互关系，相关，关连

参考例句：

• The second group of measurements had a high correlation with the first.第二组测量数据与第一组高度相关。
• A high correlation exists in America between education and economic position.教育和经济地位在美国有极密切的关系。

6 mechanism   

n.机械装置；机构，结构

参考例句：

• The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
• The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。

7 disastrous   

adj.灾难性的，造成灾害的；极坏的，很糟的

参考例句：

• The heavy rainstorm caused a disastrous flood.暴雨成灾。
• Her investment had disastrous consequences.She lost everything she owned.她的投资结果很惨，血本无归。