2007年VOA标准英语-West Nile Virus Killing Several North American

By David McAlary
Washington
16 May 2007

Scientists say West Nile virus is killing¹ large numbers of birds across North America. The organism has devastated² big proportions of several bird species that commonly populate town and city suburbs throughout the continent.  As we hear from VOA's David McAlary, the finding is a stark³ example of the potential havoc⁴ invasive species can wreak⁵.

Spring in North America has brought the usual seasonal⁶ sounds of birds. But this spring, as for the past few years, the sounds of many bird species are fading.

Scientists say the arrival of West Nile Virus in the United States eight years ago has taken a significant toll⁷ on seven of 20 bird species whose populations they assessed.

The American Crow, Corvus brachyrhynchos

Among the hardest hit are crows.

"In some regions, this species decreased up to 45 percent, and that includes routes or locations where the bird decreased closer to 90 percent," noted⁸ Shannon LaDeau of the Smithsonian Institution's Migratory⁹ Bird Center in Washington.  "Crows we definitely knew suffered high mortality when exposed to West Nile Virus, but I still think it was a surprise we were able to show such a large-scale declined in this species across the continent."

In addition to crows, LaDeau and colleagues report in the journal Nature that six other species declined by one-third to two-thirds in some regions. Among them blue jays, the American robin¹⁰, chickadees, as well as the tufted titmouse, the house wren¹¹, and the Eastern bluebird.

"One other surprise that we had was actually the Eastern bluebird, which in the United States is a well-recognized, bright blue bird that suffered pretty significant decline after 2002, which is tightly correlated with when we had human epidemics¹² of West Nile Virus in those same regions," she added.

LaDeau says that of the seven bird species affected¹³, only the blue jay and house wren populations returned to normal by 2005.

She and her colleagues determined¹⁴ the virus' impact on birds by examining bird population surveys going back 26 years.  The surveys are conducted by observers along regular North American bird routes.

The researchers say the declines occurred as West Nile Virus moved across the continent and, as in the case of the bluebirds, were geographically¹⁵ highly correlated with the intensity¹⁶ of the disease's transmission in people.

In a Nature magazine podcast, LaDeau says the species were not previously¹⁷ endangered.

"An invasive pathogen [disease] like this can have really important and often devastating¹⁸ impacts on ecosystems¹⁹ that we are not monitoring as endangered ecosystems," she explained.  "So in this case, we have several mainland species of very common birds that are not known to be endangered that are really responding quite dramatically to the introduction of this novel pathogen."

LaDeau points out that bird losses can have serious environmental consequences. The decrease in robins²⁰ has been linked to more mosquitos feeding on people and intensified²¹ West Nile Virus epidemics.

1 killing   

n.巨额利润；突然赚大钱，发大财

参考例句：

• Investors are set to make a killing from the sell-off.投资者准备清仓以便大赚一笔。
• Last week my brother made a killing on Wall Street.上个周我兄弟在华尔街赚了一大笔。

2 devastated   

v.彻底破坏( devastate的过去式和过去分词)；摧毁；毁灭；在感情上（精神上、财务上等）压垮adj.毁坏的；极为震惊的

参考例句：

• The bomb devastated much of the old part of the city. 这颗炸弹炸毁了旧城的一大片地方。
• His family is absolutely devastated. 他的一家感到极为震惊。

3 stark   

adj.荒凉的；严酷的；完全的；adv.完全地

参考例句：

• The young man is faced with a stark choice.这位年轻人面临严峻的抉择。
• He gave a stark denial to the rumor.他对谣言加以完全的否认。

4 havoc   

n.大破坏，浩劫，大混乱，大杂乱

参考例句：

• The earthquake wreaked havoc on the city.地震对这个城市造成了大破坏。
• This concentration of airborne firepower wrought havoc with the enemy forces.这次机载火力的集中攻击给敌军造成很大破坏。

5 wreak   

v.发泄；报复

参考例句：

• She had a burning desire to wreak revenge.她复仇心切。
• Timid people always wreak their peevishness on the gentle.怯懦的人总是把满腹牢骚向温和的人发泄。

6 seasonal   

adj.季节的，季节性的

参考例句：

• The town relies on the seasonal tourist industry for jobs.这个城镇依靠季节性旅游业提供就业机会。
• The hors d'oeuvre is seasonal vegetables.餐前小吃是应时蔬菜。

7 toll   

n.过路(桥)费；损失，伤亡人数；v.敲(钟)

参考例句：

• The hailstone took a heavy toll of the crops in our village last night.昨晚那场冰雹损坏了我们村的庄稼。
• The war took a heavy toll of human life.这次战争夺去了许多人的生命。

8 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

9 migratory   

n.候鸟，迁移

参考例句：

• Many migratory birds visit this lake annually.许多候鸟每年到这个湖上作短期逗留。
• This does not negate the idea of migratory aptitude.这并没有否定迁移能力这一概念。

10 robin   

n.知更鸟，红襟鸟

参考例句：

• The robin is the messenger of spring.知更鸟是报春的使者。
• We knew spring was coming as we had seen a robin.我们看见了一只知更鸟，知道春天要到了。

11 wren   

n.鹪鹩；英国皇家海军女子服务队成员

参考例句：

• A wren is a kind of short-winged songbird.鹪鹩是一种短翼的鸣禽。
• My bird guide confirmed that a Carolina wren had discovered the thickets near my house.我掌握的鸟类知识使我确信，一只卡罗莱纳州鹪鹩已经发现了我家的这个灌木丛。

12 epidemics   

n．流行病

参考例句：

• Reliance upon natural epidemics may be both time-consuming and misleading. 依靠天然的流行既浪费时间，又会引入歧途。
• The antibiotic epidemics usually start stop when the summer rainy season begins. 传染病通常会在夏天的雨季停止传播。

13 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

14 determined   

adj.坚定的；有决心的

参考例句：

• I have determined on going to Tibet after graduation.我已决定毕业后去西藏。
• He determined to view the rooms behind the office.他决定查看一下办公室后面的房间。

15 geographically   

adv.地理学上，在地理上，地理方面

参考例句：

• Geographically, the UK is on the periphery of Europe. 从地理位置上讲，英国处于欧洲边缘。 来自辞典例句
• All these events, however geographically remote, urgently affected Western financial centers. 所有这些事件，无论发生在地理上如何遥远的地方，都对西方金融中心产生紧迫的影响。 来自名作英译部分

16 intensity   

n.强烈，剧烈；强度；烈度

参考例句：

• I didn't realize the intensity of people's feelings on this issue.我没有意识到这一问题能引起群情激奋。
• The strike is growing in intensity.罢工日益加剧。

17 previously   

adv.以前，先前（地）

参考例句：

• The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。

18 devastating   

adj.毁灭性的，令人震惊的，强有力的

参考例句：

• It is the most devastating storm in 20 years.这是20年来破坏性最大的风暴。
• Affairs do have a devastating effect on marriages.婚外情确实会对婚姻造成毁灭性的影响。

19 ecosystems   

n.生态系统( ecosystem的名词复数 )

参考例句：

• There are highly sensitive and delicately balanced ecosystems in the forest. 森林里有高度敏感、灵敏平衡的各种生态系统。 来自《简明英汉词典》
• Madagascar's ecosystems range from rainforest to semi-desert. 马达加斯加生态系统类型多样，从雨林到半荒漠等不一而足。 来自辞典例句

20 robins   

n.知更鸟，鸫( robin的名词复数 )；（签名者不分先后，以避免受责的）圆形签名抗议书（或请愿书）

参考例句：

• The robins occupied their former nest. 那些知更鸟占了它们的老窝。 来自《现代汉英综合大词典》
• Benjamin Robins then entered the fray with articles and a book. 而后，Benjamin Robins以他的几篇专论和一本书参加争论。 来自辞典例句

21 intensified   

v.（使）增强， （使）加剧( intensify的过去式和过去分词 )

参考例句：

• Violence intensified during the night. 在夜间暴力活动加剧了。
• The drought has intensified. 旱情加剧了。 来自《简明英汉词典》