每日一翻：Coyote Size Forces Smartness

Coyotes. In the last two decades they’ve become common in almost every North American metropolitan area. Stanley Gehrt is a wildlife ecologist at Ohio State University who studies urban coyotes in Chicago. He spoke October 20th at the ScienceWriters2014 meeting in Columbus, Ohio, about why coyotes are so good at adapting to various environments:

过去20年间，在北美的几乎每个大都市区域中土狼变得很普遍。Stanley Gehrt 是俄亥俄州立大学的一个野生动物生态学家，他在芝加哥研究城市土狼。10月20号，在俄亥俄州哥伦布市的ScienceWriters2014会议上，他讲述了土狼为什么善于在各种环境中生存。

“For mammalian carnivores, the 20-kilogram point, 20 to 21 kilograms, is the key here. Because mammalian predators that stay below that number can exist on prey smaller than them. And they’re often solitary or they only form small groups. And they can scavenge and be able to meet their energetic needs.

对于哺乳类食肉动物来说，20公斤或者20到21公斤是个分界点。因为在这个数字以下的哺乳动物捕食者能够以比它们个头小的的动物为食而生存。并且它们经常独居或者仅仅是小规模的群居。它们可以以此为食并且能满足它们的体能需求。

“But if they exceed 20 kilograms in body weight, now they have to eat prey that’s their size or larger to be able to maintain their energetic requirement. So they often are hunting prey larger than them, which requires often sociality. And so that’s why wolves rely a lot on deer, moose, elk, that they have to hunt cooperatively.

但是如果它们体重超过20公斤，那么它们就只能捕食那些个头和它们一样大或比它们更大的动物来维持体能需求。所以它们经常捕食比它们个头大的猎物，而这个经常需要互相合作。所以这就是狼为什么非常依赖那些需要它们彼此合作才能捕到的动物，比如鹿，驼鹿，麋鹿。

“Some of our coyotes get right to that 20-kilogram level, and that’s the perfect spot, because what they can do is they can either exist quite well on prey smaller than them, and that’s typically what they do, or if they have to, if the conditions dictate it, then they can hunt and consume prey larger than them. So they can do whatever they need to do. As opposed to the others, you’ll never see foxes taking down prey that are their size or larger, or rarely will you see that. And you won’t see wolves living off of really small prey, rodents, for any length of time, they will temporarily but not for a long time. So this kind of sets the stage for the perfect predator here.

一些土狼刚好到20公斤级别，这是一个完美的点，因为它们能做的是它们可以依赖比它们个头小的猎物而生存的很好，这是它们典型的做法；或者如果他们必须或者条件逼迫它们必须这么做的时候，它们又可以捕食比它们大的动物。所以它们可以做任何它们需要做的事。相对于其他的动物，你永远不会看到狐狸捕食和它们一样大的或者比它们还要大的动物，或者说几乎不可能看到。任何一段时间，你都不会看到狼一直以比它们小的猎物或啮齿动物为食，它们只是临时这么做而不会长久性如此。这就为成为完美的捕食者而奠定了基础。

“Also, being in the middle means that they are also subjected to predation at times by the larger predators such as wolves and mountain lions, and the occasional bear. So they have to be extra good at hunting their own prey as well as not becoming prey themselves. So it creates a super-smart animal.”

同样，处于中级水平也意味着它们有时也会成为比它们更大的捕食者的口中餐，比如狼，美洲狮，偶尔还会是熊。所以在擅长猎取自己的食物之外，它们还不能让自己变成食物。如此便成就了这种超级聪明的动物。

—Steve Mirsky