密歇根新闻广播 是什么原因导致君主斑蝶数量锐减?

 

Monarch¹ butterflies are not around in the numbers they used to be — not by a long shot. By some estimates, monarch populations have dropped by 90% over the past twenty years.

But why has that happened to these iconic butterflies?

On a butterfly survey

I took a walk with Jerry Wiedman to count butterflies. He's a retired² chemist. Wiedman brought a clipboard, and a butterfly net with a pole almost as tall as he is. We walked around a park that overlooks Lake Erie in northeast Ohio.

This isn't just a casual walk. This path through meadows and woods is what's called a butterfly transect. Wiedman and others set it up.

"And we count butterflies within 7.5 feet on either side of us," he said.

As we walked, he jotted³ down how many butterflies and what species we saw.

"There's your red admiral, see him?"

Wiedman has been fascinated with butterflies since he was a kid.

A mystery of nature

For many young people, monarch butterflies are the first to get their attention. Their large orange and black wings are easy to spot. And their migration⁴ story is a mystery of nature.

Each spring, these tiny, fluttering creatures fly thousands of miles. They leave their winter homes in forests high in the mountains of Mexico, and the females lay eggs on milkweed plants in the southern U.S.

Most monarchs⁵ live only a few weeks. So the new butterflies continue the journey started by their parents. It can take five generations to complete one migration to Canada.

Some years, Wiedman has personally counted hundreds of monarchs migrating through Ohio.

But that's changed. 

"We don't get the the numbers we did in the late 90s or early 2000," he said.

A troubling downward trend

His counts show fluctuations⁶ in the monarch population, but it's a downward trend. It's the same story around the country.

Chip Taylor is the director of Monarch Watch at the University of Kansas and he says monarch numbers started to plummet⁷ in the early 2000s. That's when new farming technology — known as Roundup Ready (glyphosate-resistant) seeds — became popular. With Roundup Ready seeds, farmers could spray entire fields with herbicide. The weeds would die, but the crops were fine.

Taylor says it also killed off the milkweed, and that's the only food monarch caterpillars⁸ can eat.

"You know, I've got really nice pictures of milkweed growing in corn and soybean fields around the year 2000. Then around 2006 you couldn't find milkweed growing in corn and soybean fields anywhere. I mean it was just about impossible," he says.

Around 2007, President Bush made a push for huge increases in corn-based ethanol and other homegrown sources of energy. With the help of Roundup Ready technology, many farmers planted corn and soy on land that had been fallow, or in conservation. This killed off even more milkweed. 

"And the estimate is that we've lost 100 million acres of habitat just to the adoption⁹ of this particular technology," says Taylor.

Should the monarch be listed as threatened?

According to estimates by the Center for Biological Diversity, monarch populations have dropped by about 970 million since the mid¹⁰ 1990s. They've petitioned the U.S. Fish and Wildlife Service to protect the monarch as threatened under the Endangered Species Act.

Taylor argues against that.

"I don't think they should be listed as threatened. I think that is counterproductive. The value of this petition is that it's caught everybody's attention," he says.

He says regulation could set up conflicts between farmers and the federal government.

Still, he sees a need to restore tens of thousands of acres of habitat for the butterflies. He says that's already starting to happen, with many people planting milkweed in their home gardens and teaching children about it in school.

1 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。

2 retired   

adj.隐退的，退休的，退役的

参考例句：

• The old man retired to the country for rest.这位老人下乡休息去了。
• Many retired people take up gardening as a hobby.许多退休的人都以从事园艺为嗜好。

3 jotted   

v.匆忙记下( jot的过去式和过去分词 )；草草记下，匆匆记下

参考例句：

• I jotted down her name. 我匆忙记下了她的名字。 来自《简明英汉词典》
• The policeman jotted down my address. 警察匆匆地将我的地址记下。 来自《现代英汉综合大词典》

4 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。

5 monarchs   

君主，帝王( monarch的名词复数 )

参考例句：

• Monarchs ruled England for centuries. 世袭君主统治英格兰有许多世纪。
• Serving six monarchs of his native Great Britain, he has served all men's freedom and dignity. 他在大不列颠本国为六位君王服务，也为全人类的自由和尊严服务。 来自演讲部分

6 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。

7 plummet   

vi.(价格、水平等)骤然下跌；n.铅坠；重压物

参考例句：

• Mengniu and Yili have seen their shares plummet since the incident broke.自事件发生以来，蒙牛和伊利的股票大幅下跌。
• Even if rice prices were to plummet,other brakes on poverty alleviation remain.就算大米价格下跌，其它阻止导致贫困的因素仍然存在。

8 caterpillars   

n.毛虫( caterpillar的名词复数 )；履带

参考例句：

• Caterpillars eat the young leaves of this plant. 毛毛虫吃这种植物的嫩叶。
• Caterpillars change into butterflies or moths. 毛虫能变成蝴蝶或蛾子。 来自辞典例句

9 adoption   

n.采用，采纳，通过；收养

参考例句：

• An adoption agency had sent the boys to two different families.一个收养机构把他们送给两个不同的家庭。
• The adoption of this policy would relieve them of a tremendous burden.采取这一政策会给他们解除一个巨大的负担。

10 mid   

adj.中央的，中间的

参考例句：

• Our mid-term exam is pending.我们就要期中考试了。
• He switched over to teaching in mid-career.他在而立之年转入教学工作。