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科学美国人60秒 SSS New Data on Killer House Cats

时间:2020-05-06 09:02来源:互联网 提供网友:nan   字体: [ ]
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Wild cats kill more animals than domestic ones do. But pet cats kill many more of them in a small area than similarly sized wild predators1.

Full Transcript2 

Domestic cats that live or go outside kill lots of wild animals. Recent studies find that outdoor cats in North America take out between 10 and 30 billion birds and mammals each year.

Still, it hasn’t been clear what kind of an impact the world’s 600 million pet cats have on wildlife populations—and whether that impact poses a threat to biodiversity conservation.

“Anyone who has a cat sees their cats bring animals home. And the question is, ‘Well, does it matter?’ And especially, we wanted to know, ‘Where are the cats actually hunting? Are they hunting in their backyards? Or are they going out into the nature preserves?’”

North Carolina State University zoologist3 Roland Kays.

Together with colleagues in the U.K., Australia and New Zealand, Kays distributed small GPS trackers to citizen-scientist cat owners. They attached the trackers to their cats’ collars. In all, more than 900 pet cats were tracked this way, all of which were routinely allowed to roam freely outside.

Some cats were true explorers. One British cat called Max walked almost two kilometers back and forth4 along a road between two neighboring villages—twice! But the majority were homebodies, rarely straying more than 100 meters from home. In other words, they used their own backyards, plus those of a few neighbors, as their hunting grounds. The findings are in the journal Animal Conservation. [Roland Kays et al., The small home ranges and large local ecological5 impacts of pet cats]

A single pet cat doesn’t kill as many animals as a wild cat does to survive. But the pet’s impact happens in a much smaller area. So in a given area, say 100 square meters, pet cats kill between two and 10 times as many other animals as do similarly sized wild predators.  

“We were able to put this into kind of a currency, into a value of ‘How many prey6 animals does a pet cat kill per hectare, sort of per area, per year?’ And that’s something we can also estimate for wild predators. So we were able to estimate this for a wild cat called the jungle cat, which is about the same size. And they kill a lot more per cat because they have to hunt to get everything that they eat, whereas the pet cats get their food bowl. But they hunt over a massive area, compared to the pet cats.”

And in some places, including California, Florida, Australia and elsewhere, cats were an important threat to some species that are already in trouble.

“On one hand, it’s kind of good news that the cats aren’t going out further abroad. But it’s bad news that they're quite likely to have an impact on animals they share space with near their houses.”

With so much killing7 concentrated around people's houses, the positive impacts of urban wildlife—like the beauty of songbirds or the way small lizards8 can control insect pests—could get washed away in precisely9 the areas where those benefits are most appreciated. So when conservationists implore10 cat owners to keep their pets indoors, scientific evidence agrees.

—Jason G. Goldman

[The above text is a transcript of this podcast.]


点击收听单词发音收听单词发音  

1 predators 48b965855934a5395e409c1112d94f63     
n.食肉动物( predator的名词复数 );奴役他人者(尤指在财务或性关系方面)
参考例句:
  • birds and their earthbound predators 鸟和地面上捕食它们的动物
  • The eyes of predators are highly sensitive to the slightest movement. 捕食性动物的眼睛能感觉到最细小的动静。 来自《简明英汉词典》
2 transcript JgpzUp     
n.抄本,誊本,副本,肄业证书
参考例句:
  • A transcript of the tapes was presented as evidence in court.一份录音带的文字本作为证据被呈交法庭。
  • They wouldn't let me have a transcript of the interview.他们拒绝给我一份采访的文字整理稿。
3 zoologist MfmwY     
n.动物学家
参考例句:
  • Charles darwin was a famous zoologist.查尔斯达尔文是一位著名的动物学家。
  • The zoologist had spent a long time living with monkeys.这位动物学家与猴子一起生活了很长时间。
4 forth Hzdz2     
adv.向前;向外,往外
参考例句:
  • The wind moved the trees gently back and forth.风吹得树轻轻地来回摇晃。
  • He gave forth a series of works in rapid succession.他很快连续发表了一系列的作品。
5 ecological IrRxX     
adj.生态的,生态学的
参考例句:
  • The region has been declared an ecological disaster zone.这个地区已经宣布为生态灾难区。
  • Each animal has its ecological niche.每种动物都有自己的生态位.
6 prey g1czH     
n.被掠食者,牺牲者,掠食;v.捕食,掠夺,折磨
参考例句:
  • Stronger animals prey on weaker ones.弱肉强食。
  • The lion was hunting for its prey.狮子在寻找猎物。
7 killing kpBziQ     
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。
8 lizards 9e3fa64f20794483b9c33d06297dcbfb     
n.蜥蜴( lizard的名词复数 )
参考例句:
  • Nothing lives in Pompeii except crickets and beetles and lizards. 在庞培城里除了蟋蟀、甲壳虫和蜥蜴外,没有别的生物。 来自辞典例句
  • Can lizards reproduce their tails? 蜥蜴的尾巴断了以后能再生吗? 来自辞典例句
9 precisely zlWzUb     
adv.恰好,正好,精确地,细致地
参考例句:
  • It's precisely that sort of slick sales-talk that I mistrust.我不相信的正是那种油腔滑调的推销宣传。
  • The man adjusted very precisely.那个人调得很准。
10 implore raSxX     
vt.乞求,恳求,哀求
参考例句:
  • I implore you to write. At least tell me you're alive.请给我音讯,让我知道你还活着。
  • Please implore someone else's help in a crisis.危险时请向别人求助。
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TAG标签:   科学美国人60秒  英语听力  sss
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