美国科学60秒 SSS 2013-08-02_在线英语听力室_免费在线英语听力学习网站

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　　This is Scientific American 60-second Science. I'm Sophie Bushwick. Got a minute?

　　Wolves and grizzlies¹ sound like unlikely allies. But the resurgence² of Yellowstone Park's canine³ population has helped the bears in a berry interesting way.

　　In the 1990s, people reintroduced wolves to Yellowstone Park, where they had been absent for most of the century. As their population grew, they began hunting elk⁴, reducing their number. And with fewer elk snacking on berries, more fruit remained available for bears.

　　Comparisons of grizzly⁵ scat collected in the years before and after the wolves’ return showed an increase in the bears’ berry consumption, particularly during the months of July and August. The study is in the Journal of Animal Ecology.

　　Fruit can make up fully⁶ half of a grizzly’s diet as it prepares for hibernation⁷. But bears and berries aren’t the only ones to benefit from wolves. The canine comeback also boosted the growth of popular elk foods such as aspen and willow⁸ trees， which proves even a single species can have a berry strong ecosystem⁹ effect.

　　Thanks for the minute for Scientific American 60-second Science. I'm Sophie Bushwick.

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1 grizzlies
北美洲灰熊( grizzly的名词复数 )
参考例句：
The Suns beat the Memphis Grizzlies 127-113 earlier Tuesday night. 在周二晚上早些时候，太阳以127：113击败孟菲斯灰熊。 Whatever you do, do not blink.They're like grizzlies. 无论你做什么，别眨眼。他们跟熊有点相象。

2 resurgence
n.再起，复活，再现
参考例句：
A resurgence of his grief swept over Nim.悲痛又涌上了尼姆的心头。 Police say drugs traffickers are behind the resurgence of violence.警方说毒贩是暴力活动重新抬头的罪魁祸首。

3 canine
adj.犬的，犬科的
参考例句：
The fox is a canine animal.狐狸是犬科动物。 Herbivorous animals have very small canine teeth,or none.食草动物的犬牙很小或者没有。

4 elk
n.麋鹿
参考例句：
I was close enough to the elk to hear its labored breathing.我离那头麋鹿非常近，能听见它吃力的呼吸声。 The refuge contains the largest wintering population of elk in the world.这座庇护所有着世界上数量最大的冬季麋鹿群。

5 grizzly
adj.略为灰色的，呈灰色的；n.灰色大熊
参考例句：
This grizzly liked people.这只灰熊却喜欢人。 Grizzly bears are not generally social creatures.一般说来，灰熊不是社交型动物。

6 fully
adv.完全地，全部地，彻底地；充分地
参考例句：
The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气，然后全部呼出。 They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。

7 hibernation
n.冬眠
参考例句：
Bears wake up in the spring after a winter of hibernation.熊经过一个冬天的冬眠后在春季苏醒。 The tortoise spends the winter months in hibernation.乌龟在冬眠中度过寒冬季节。

8 willow
n.柳树
参考例句：
The river was sparsely lined with willow trees.河边疏疏落落有几棵柳树。 The willow's shadow falls on the lake.垂柳的影子倒映在湖面上。

9 ecosystem
n.生态系统
参考例句：
This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。 We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。