VOA慢速英语2013 As It Is - Nature:butterfly and how roosters know when to crow

 

As It Is - Nature:butterfly and how roosters know when to crow

Hi there. I’m Kelly Jean Kelly. Today on As It Is, we are talking about nature.

Specifically, about how roosters know when to crow, and one of the largest eggs the world has ever seen. But first, Caty Weaver¹ takes us to the Smithsonian Institution’s Natural History Museum in Washington, DC. Visitors to the museum have a rare opportunity to be surrounded by hundreds of living butterflies.

The Live Butterfly Pavilion is one of the Natural History Museum’s most popular exhibits. The Pavilion-- which, in this case, is a warm room -- is filled with flowering plants and 50 different species of butterflies.

“We have butterflies from Asia and from Africa, and South and Central America, and here in the United States.”

Dan Babbitt manages the exhibit. He says the butterflies are shipped from their native countries to the museum while they are in chrysalis state. That means they travel after they have built a protective covering around themselves.

“We unpack² them, we hang them up and wait for them to emerge until they’re a butterfly and then we’ll release them into the exhibit.”

One of the butterflies in the Pavilion is called a Blue Morpho, from the Amazon region of South America. It is the size of a person’s hand and has bright blue wings. Another is a black and red Asian butterfly called a Scarlet³ Mormon. One of them landed on nine-year-old Gunnar Bruce’s head.

“It’s just cool how the butterflies are all over. I feel like the butterfly really, like, likes me.”

Gunnar says he is enjoying learning more about butterflies.

“I learned that there’s lots of different kinds of species and that they only live for about three weeks.”

So is nine-year-old Ava Canales.

“I learned that when butterflies flutter when they eat, it’s because they can’t balance on the flowers.”

Exhibit manager Dan Babbitt says visitors also learn why butterflies are important to our environment.

“They will travel from flower to flower, taking pollen⁴ from one flower and depositing it into another, enabling that flower to be able to create seeds and disperse⁵. So we wouldn’t have a number of our flowers that we like to look at and fruit that we like to eat without the butterfly. Butterflies are also important as a food source, for a number of birds and other insects. They are either eaten as a butterfly or as the caterpillar⁶.”

But Mr. Babbitt says many butterfly species – such as the Monarch⁷ – are dying off.

“That’s something that we really need to watch out for and really focus on – the issues of deforestation and use of pesticides⁸ and just general land management issues, to make sure that we can provide for these butterflies. But also for all of wildlife and for us, to make sure that we have a healthy environment.”

He hopes the Live Butterfly Pavilion will help raise public awareness⁹ about the future of the butterfly.

I’m Caty Weaver.

We go now from a very quiet animal to a very loud one.

If you live near a rooster, you can depend on hearing him every morning when the sun comes up. But how do roosters know when it is time to crow? Christopher Cruise explains.

Japanese researchers say they have proof that an internal clock helps tell roosters when it is time to crow. That internal clock is often called a “Circadian rhythm.” It naturally links many plants and animals—including humans—with the Earth’s 24-hour cycle.

Researchers Takashi Yoshimura and Tsuyoshi Shimmura wanted to learn how Circadian rhythm works in roosters. Did they have an internal sense of what time it was? Or did they just react to the morning sun?

The researchers kept roosters in constant early morning light. Then they turned on their recorders so they could watch and listen.

The roosters crowed all day. But, they crowed the loudest first thing in the morning. The researchers believe this finding means that roosters naturally “know” what time of day it is.

However, the researchers also noticed that the roosters’ sense of time grew worse the longer they stayed in the experiment. The researchers say this observation suggests that external information, such as irregular light or the sound of other roosters, can weaken a rooster’s Circadian rhythm.

Mr. Yoshimura and Mr. Shimmura published their findings in the journal Current Biology. Mr. Yoshimura says scientists still do not know why a dog says “bow-wow” and a cat says “meow.” But, he says roosters can teach us more about genetically¹⁰ controlled behavior.

I’m Christopher Cruise.

And finally, we turn our attention to a giant egg in London. Christie’s Auction¹¹ House is selling a rare, fossilized egg from the extinct elephant bird.

Elephant birds lived in Madagascar, off the east coast of Africa. They were the largest birds ever to have lived. An elephant bird looked a little a lot like an ostrich¹². It was about three and a half meters high. elephant birds disappeared sometime between the 13th and 17th centuries. It is thought they were hunted to extinction¹³.

Experts with Christie’s say elephant bird eggs are even larger than dinosaur¹⁴ eggs. The one in London measures 30 centimeters high and 21 centimeters wide. That is about 120 times the size of an ordinary chicken egg. Christie’s will auction the egg in London on April 24. Officials expect that it could sell for more than $45,000.

That’s it for “As It Is” today.

1 weaver   

n.织布工；编织者

参考例句：

• She was a fast weaver and the cloth was very good.她织布织得很快，而且布的质量很好。
• The eager weaver did not notice my confusion.热心的纺织工人没有注意到我的狼狈相。

2 unpack   

vt.打开包裹（或行李），卸货

参考例句：

• I must unpack before dinner.我得在饭前把行李打开。
• She said she would unpack the items later.她说以后再把箱子里的东西拿出来。

3 scarlet   

n.深红色，绯红色，红衣；adj.绯红色的

参考例句：

• The scarlet leaves of the maples contrast well with the dark green of the pines.深红的枫叶和暗绿的松树形成了明显的对比。
• The glowing clouds are growing slowly pale,scarlet,bright red,and then light red.天空的霞光渐渐地淡下去了，深红的颜色变成了绯红，绯红又变为浅红。

4 pollen   

n.[植]花粉

参考例句：

• Hummingbirds have discovered that nectar and pollen are very nutritious.蜂鸟发现花蜜和花粉是很有营养的。
• He developed an allergy to pollen.他对花粉过敏。

5 disperse   

vi.使分散；使消失；vt.分散；驱散

参考例句：

• The cattle were swinging their tails to disperse the flies.那些牛甩动着尾巴驱赶苍蝇。
• The children disperse for the holidays.孩子们放假了。

6 caterpillar   

n.毛虫，蝴蝶的幼虫

参考例句：

• A butterfly is produced by metamorphosis from a caterpillar.蝴蝶是由毛虫脱胎变成的。
• A caterpillar must pass through the cocoon stage to become a butterfly.毛毛虫必须经过茧的阶段才能变成蝴蝶。

7 monarch   

n.帝王，君主，最高统治者

参考例句：

• The monarch's role is purely ceremonial.君主纯粹是个礼仪职位。
• I think myself happier now than the greatest monarch upon earth.我觉得这个时候比世界上什么帝王都快乐。

8 pesticides   

n.杀虫剂( pesticide的名词复数 )；除害药物

参考例句：

• vegetables grown without the use of pesticides 未用杀虫剂种植的蔬菜
• There is a lot of concern over the amount of herbicides and pesticides used in farming. 人们对农业上灭草剂和杀虫剂的用量非常担忧。 来自《简明英汉词典》

9 awareness   

n.意识，觉悟，懂事，明智

参考例句：

• There is a general awareness that smoking is harmful.人们普遍认识到吸烟有害健康。
• Environmental awareness has increased over the years.这些年来人们的环境意识增强了。

10 genetically   

adv.遗传上

参考例句：

• All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
• Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物

11 auction   

n.拍卖；拍卖会；vt.拍卖

参考例句：

• They've put the contents of their house up for auction.他们把房子里的东西全都拿去拍卖了。
• They bought a new minibus with the proceeds from the auction.他们用拍卖得来的钱买了一辆新面包车。

12 ostrich   

n.鸵鸟

参考例句：

• Ostrich is the fastest animal on two legs.驼鸟是双腿跑得最快的动物。
• The ostrich indeed inhabits continents.鸵鸟确实是生活在大陆上的。

13 extinction   

n.熄灭，消亡，消灭，灭绝，绝种

参考例句：

• The plant is now in danger of extinction.这种植物现在有绝种的危险。
• The island's way of life is doomed to extinction.这个岛上的生活方式注定要消失。

14 dinosaur   

n.恐龙

参考例句：

• Are you trying to tell me that David was attacked by a dinosaur?你是想要告诉我大卫被一支恐龙所攻击？
• He stared at the faithful miniature of the dinosaur.他凝视著精确的恐龙缩小模型。