北京KET PET :科學(xué)美國(guó)人60S之家貓殺手
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This is Scientific American's 60-second Science, I'm Jason Goldman.
這里是科學(xué)美國(guó)人——60秒科學(xué)系列，我是杰森·古德曼。
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.
在外生活或外出的家貓會(huì)殺死許多野生動(dòng)物。最新研究發(fā)現(xiàn)，北美的戶外貓每年會(huì)干掉100億到300億只鳥(niǎo)和哺乳動(dòng)物。
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.
不過(guò)，目前尚不清楚全球6億只寵物貓對(duì)野生動(dòng)物種群有何影響，以及這種影響是否對(duì)生物多樣性保護(hù)構(gòu)成威脅。
"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 zoologist Roland Kays.
“養(yǎng)貓的人都看見(jiàn)過(guò)貓將動(dòng)物叼回家。問(wèn)題是‘這重要嗎？’特別是，我們想知道‘貓到底在哪里捕獵？是在后院還是到自然保護(hù)區(qū)捕的獵？’”
北卡羅來(lái)納州立大學(xué)的動(dòng)物學(xué)家羅蘭·凱斯說(shuō)到。
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.
凱斯和英國(guó)、澳大利亞和新西蘭的同事一起向養(yǎng)貓的公民科學(xué)家分發(fā)小型GPS追蹤器。他們將追蹤器貼在貓的項(xiàng)圈上。他們用這種方法一共追蹤了900多只寵物貓，這些貓都像往常一樣被允許外出自由活動(dòng)。
Some cats were true explorers. One British cat called Max walked almost two kilometers back and forth 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.
有些貓是真正的探險(xiǎn)家。一只名為馬克斯的英國(guó)貓沿著兩個(gè)相鄰村莊之間的公路來(lái)回走了近兩公里！但大多數(shù)貓都很宅，很少離家100米以上。換句話說(shuō)，它們將自家后院以及幾個(gè)鄰居的后院當(dāng)做狩獵場(chǎng)。這項(xiàng)研究發(fā)表在《動(dòng)物保護(hù)》期刊上。
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.
單只寵物貓不會(huì)像野貓為了生存而殺死那么多動(dòng)物。但寵物貓的影響范圍要小得多。比如在100平方米的區(qū)域內(nèi)，寵物貓殺死的動(dòng)物數(shù)量是體型相似的野貓的2到10倍。單只寵物貓不會(huì)像野貓為了生存而殺死那么多動(dòng)物。但寵物貓的影響范圍要小得多。比如在100平方米的區(qū)域內(nèi)，寵物貓殺死的動(dòng)物數(shù)量是體型相似的野貓的2到10倍。
"We were able to put this into kind of a currency, into a value of 'How many prey 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."
“我們能將此轉(zhuǎn)換成一種貨幣，估算‘一只寵物貓每年在每公頃或第片區(qū)域內(nèi)殺死多少只獵物’。我們還能估算野貓的情況。因此，我們可以估算與家貓?bào)w型相似、被稱(chēng)為森林貓的一種野貓的情況。這種貓殺死的獵物數(shù)量比家貓多得多，因?yàn)樗鼈儽仨氁揽坎东C獲得一切食物，而寵物貓只需去食盆享用食物。但與寵物貓相比，它們的兒捕獵面積更大?！?/span>
And in some places, including California, Florida, Australia and elsewhere, cats were an important threat to some species that are already in trouble.
在加利福尼亞州、佛羅里達(dá)州、澳大利亞等地，貓是某些已經(jīng)陷入困境的物種的重大威脅。
"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."
“一方面，貓不去太遠(yuǎn)的地方是個(gè)好消息。但壞消息是，它們很可能會(huì)對(duì)與它們共享空間的動(dòng)物產(chǎn)生影響?！?/span>
With so much killing concentrated around people's houses, the positive impacts of urban wildlife—like the beauty of songbirds or the way small lizards can control insect pests—could get washed away in precisely the areas where those benefits are most appreciated. So when conservationists implore cat owners to keep their pets indoors, scientific evidence agrees.
由于人類(lèi)住宅周?chē)辛巳绱硕嗟摹皻⒙尽?，城市野生?dòng)物的積極影響，比如鳴鳥(niǎo)的美麗或小蜥蜴控制害蟲(chóng)的能力，可能會(huì)被清洗掉，而遭清洗的地點(diǎn)恰恰是最欣賞這些益處的區(qū)域。因此，自然環(huán)境保護(hù)主義者懇求養(yǎng)貓人讓貓待在室內(nèi)的做法，得到了科學(xué)證據(jù)的支持。
Thanks for listening for Scientific American's 60-second Science. I'm Jason Goldman.
謝謝大家收聽(tīng)科學(xué)美國(guó)人——60秒科學(xué)。我是杰森·古德曼。
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