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更新时间:2015-10-4 9:38:57 来源:纽约时报中文网 作者:佚名

When the Cat Comes Back, With Prey

Jennifer L. McDonald is an ecologist by profession and a cat person by avocation. Some years ago, Tiggy, her ginger-and-white shorthair, would bring home freshly killed mice and shrews for her consideration.

珍妮弗·麦克唐纳德(Jennifer L. McDonald)是生态学家兼爱猫人士。几年前,她养的黄白短毛猫,会把刚抓住的老鼠和鼩鼱带回家向她进贡。

Dr. McDonald, now an associate research fellow at the Center for Ecology and Conservation at the University of Exeter in England, was curious about the impact of pet cats like Tiggyon wildlife. Fewer mice might be nice. But cats, natural hunters, pounce on birds and rabbits, too.

麦克唐纳德博士是英国埃克塞特大学(University of Exeter)生态保护中心的研究员,她好奇于和自家猫咪一样的宠物猫对野生动物的影响。耗子减少可能是好事。但猫是天生的猎手,还会逮鸟和兔子。

“You can’t pick and choose a cat’s prey,” Dr. McDonald said. If owners realized how much prey their pets killed, she wondered, would they be willing to contain their cats to protect wildlife?

“你无法左右猫的捕猎对象。” 麦克唐纳德博士说。她想,如果人们意识到有多少小动物会丧命在自己的宠物爪下,他们会为了保护野生动物而限制猫咪的活动吗?

She and her associates studied the question. The answer, published recently in the journal Ecology and Evolution was unequivocal and emphatic.

她和同事们对这个问题展开了研究。答案于近期发表在《生态和进化》(Ecology and Evolution)杂志上。



In recent years, debates about the predatory effect of cats on wildlife, particularly endangered songbirds, have onlyintensified. But most public opinion surveys have focused on the management of feral cats, which make up the majority of domestic feline marauders, particularly in the United States.


Dr. McDonald surveyed owners in two British villages about cats they allowed to roam outdoors. Owners were asked to predict the amount of prey taken by their cats and documentthe actual killings. Owners in one village were then asked whether they believed pet cats had an ecological impact.


Researchers also asked owners about their willingness to keep cats indoors during prime hunting time, from dusk to dawn. The idea was flatly rejected, with some owners providing unsolicited commentary: “My cat chooses for herself whether to stay in or go out,” one wrote.


Pointing to “a dissociation between actual and perceived predatory behavior,” the researchers concluded that “the cat owners in this study reject the proposition that cats are a threat to wildlife.”


Sara J. Ash, a professor of ecology and conservation biology at the University of the Cumberlands in Williamsburg, Ky.,said that the results highlighted the deep divide between catowners, who see their individual animals as doing what comes naturally, and ecologists, who view cats as a predatory,nonnative species.

美国坎伯兰大学(University of the Cumberlands)生态学与保护生物学教授萨拉·阿什(Sara Ash)表示,研究结果突显出猫主人与生态学家之间的巨大分歧。前者认为自己宠物的行为不过是天性使然;后者则认为猫是捕食者,是外来物种。

“These owners think, ‘My cat only kills two mice a day,’­” Dr. Ash said. “But they don’t think about the high density of well-fed cats throughout their neighborhood.”

“这些猫主人认为,‘我的猫只不过一天捉两只老鼠’,” 阿什博士说,“但他们不曾想过,居民区里生活着大量营养优良的猫。”

The study’s cat owners were generally able to predict whether their pets would bring home prey, but they fared poorly atestimating how much. Among 43 cats tabulated in the Cornwall village of Mawnan Smith, the average monthlycatch ranged from none to 10. Over four months, the catsdelivered a total of 325 animals: Nearly 60 percent were rodents, and 27 percent were birds. (According to researchers, 6.2 percent were unidentifiable.)

这项研究中,猫主人基本上都预计到猫咪会带战利品回家,但对猎物数量的估计就不那么准了。在英国莫南史密斯(Mawnan Smith)的康沃尔(Cornwall)村,记录在册的43只猫平均每月捕杀猎物的数量是0到10。四个月来,这些猫带回家的小动物一共325只:约60%为啮齿类动物,27%为鸟类,(据研究人员称,有6.2%无法辨认)。

Although Mawnan Smith and another village in the study, Thornhill, in Scotland, are in rural settings, these owners’ reactions corresponded with those of urban cat owners in Britain. In a 2012 study, they said overwhelmingly that theydid not believe cats depleted certain bird populations.


John Bradshaw, a professor of anthrozoology at the University of Bristol in England, pointed out that the owners in this latest study counted only the prey their cats hadbrought home, and did not know how many creatures the cats might have left elsewhere — scenarios vividly illustrated in a 2013 University of Georgia study by researchers who attached “kitty cams” to 55 pet cats. Those cats left behind nearly half the prey they had killed.

英国布里斯托尔大学(University of Bristol)人与动物关系学(anthrozoology)教授约翰·布罗德肖(John Bradshaw)指出,最近的这次研究中,猫主人只看到猫带回家的猎物,却不知道还有多少猎物被猫带去了其它地方。

But Dr. Bradshaw, the author of “Cat Sense,” questioned whether cats were really having an ecological impact.

但布罗德肖博士怀疑猫是否真的影响生态。他是《猫的感知》(Cat Sense)一书的作者。

“No doubt pet cats kill lots of little animals, but are they doing long-term harm in the United States and Britain?” said Dr. Bradshaw, who feels that the evidence is “flimsy.”


Some researchers argue that while cats do have an impact on endangered species, notably on oceanic islands with few indigenous predators, the danger they pose in Europe and North America is hardly as significant as housing development, drought or pollution.


Noting that the biodiversity threat was insufficient to persuade owners to keep their cats indoors, Dr. McDonald and her colleagues suggested a different tactic: emphasizing the deadly hazards to pets that wander at will from, road traffic, for example, and larger predators. Increasingly, in the United States, that has meant coyotes.


According to a new study in The Journal of Mammalogy, cats, and possibly some owners, are getting the memo. American wildlife researchers investigated whether cats, which they assumed hunted mainly in residential areas, were also foraging in parks, where biodiversity is richer. Or were catsavoiding those areas because of coyotes?

根据《哺乳动物学》杂志(Journal of Mammalogy)发表的一项新研究,猫逐渐察觉到了这种威胁,大概有些猫主人也意识到了。美国野生动物研究员调查了猫是否会到物种比较丰富的公园觅食,假设这些猫主要在居民区捕猎。它们会因为土狼而避开这些区域吗?

With nearly 500 volunteers, researchers placed cameras in 32 parks and one urban area in six states, recording cat and coyote traffic. They found that many coyotes, but very few cats, stalked those protected public lands.


That was even true of Rock Creek Park in Washington, D.C.,which is surrounded by residences and likely thousands of pet cats. Yet in six months, researchers caught coyotes on camera 125 times in the park, but photographed a cat only once.

华盛顿特区的岩溪公园(Rock Creek Park)附近都是居民区,那里可能生活着成千上万只宠物猫,但是六个月间,公园的摄像机镜头捕捉到土狼125次,却只拍到一次猫。

Perhaps wary owners were keeping their cats indoors. “And maybe cats smelled coyote urine, and it struck primal fear into their little pet hearts, so they’re staying away,” saidRoland Kays, the lead author and a research associate professor of wildlife and forestry at North Carolina State University.

也许是忧心的猫主人把猫关在家里了。“也可能是猫嗅到了土狼的尿液,这让小宠物们心生畏惧,躲得远远地。” 罗兰·凯斯(Roland Kays)说,他是北卡罗来纳州立大学(North Carolina State University)野生动物和林业学研究副教授,也是该研究的第一作者。

But cats and coyotes did overlap in what researchers described as “small urban forests” — smatterings of woodland along greenways in suburban and exurban neighborhoods where coyotes are encroaching.


Studies have shown that such encounters may not end well. “Letting the cat out is not only a risk to the birds but to the cat,” Dr. Kays said.