感人！瑞典棕熊母爱恒升

　　In North America, many critters commonly encountered today—like wild turkeys or white-tailed deer—were brought back from near oblivion through conservation efforts led by hunters. Meanwhile, in Africa, some of the most charismatic species are now being hunted into extinction. But hunting can also have impacts that are far more subtle.

　　目前北美许多常见的生物(比如野生火鸡或白尾鹿)都是通过猎人的保护措施从几近被遗忘的地方所挽救回来。而在非洲那些最具魅力的物种正在被猎杀殆尽。但是你们知道狩猎还会产生其他更微妙的影响么?

　　Take the brown bear, known here in the U.S. as the grizzly. When large mammals like grizzlies are hunted, evolution might select for speedier lifecycles. That is, in order to successfully reproduce before they risk getting shot, bears might begin having cubs at a younger age. That change also allows them to reproduce more times throughout their lives. But that’s not the only possible reaction to being hunted.

　　以棕熊为例(美国称为灰熊)，灰熊这类大型哺乳动物被捕猎时，进化机制可能会为他们选择更快的生命循环。也就是说棕熊为了能够在被射杀之前成功繁殖，它们可能会在更年轻的时候开始孕育幼崽。这种变化也使他们在一生中能够多次繁衍后代。当然这种影响不单单是由人类猎杀造成的。

　　The brown bear population in Sweden has been monitored for about 30 years. And researchers in Scandinavia have noticed that females started to change their reproductive strategies. They would observe that females would keep their cubs for longer periods of time nowadays.

　　“30年内瑞典一直在检测着棕熊的数量。斯堪的纳维亚的研究人员注意到雌性的繁殖策略在逐渐改变。他们观察到雌熊照顾幼崽的时间明显加长。”

　　Usually females give birth in January while in their den… But some females, rather than weaning their cubs after one year and a half, continue to care for them for an extra year.

　　“通常情况下，雌熊1月的时候会在巢穴中产下幼崽……但是有些雌熊不在像以往一样在孩子一岁半时就给它们断奶，而是会再继续照顾它们一年。”

　　So some brown bear mothers in this population began to spend more time, not less, caring for their cubs.

　　也就是说在棕熊群体中，一些棕熊妈妈在照顾幼崽方面相比以往投入了更多的时间。

　　And we have seen that since 2005, the proportion of females that keep their cubs for two years and a half has increased dramatically. Nowadays, its about 36 percent of females that use that tactic, whereas before 2005, it was about only 7 percent or so.

　　“自2005年以来，研究发现照顾幼崽两年半的雌熊比例急剧上升。如今，大约36%的雌熊这样做，而在2005年之前，这一比例仅为7%左右。”

　　But that increased investment comes at a cost: by spending more time with their cubs, it takes longer before the mothers reproduce again. It seems as if evolution settled on a tradeoff: have fewer offspring, but invest more energy in their care. The finding is in the journal Nature Communications.

　　照顾幼崽时间的增加也是需要付出相应代价的，照顾幼崽的时间越长就意味着她们孕育周期的增加。似乎进化是在权衡：少生孩子，但在孩子的照顾上投入更多的精力。这一发现发表在自然通讯杂志上。

　　And the change can be traced to Swedish hunting regulations. The law prohibits killing females if they are accompanied by cubs. So females that happen to have the urge for extra maternal care don’t get shot—and this also gives the youngsters protection and guaranteed nutrition.

　　这种变化可以追溯到瑞典的狩猎规则。当时法律禁止猎杀有幼崽需要照顾的雌熊。因此，那些碰巧过渡宠爱幼崽的雌熊就不会被射杀—而这也为幼崽提供了足够的保护和营养。

　　The study underscores how different kinds of hunting regulations can lead to different outcomes for wild animals. This kind of knowledge helps wildlife managers ensure the long-term viability of wildlife populations, while also allowing for sustainable hunting—which itself can be a conservation tool.

　　这项研究强调了不同种类的狩猎规则会给野生动物带来不同的影响。这种知识有助于野生动物管理人员确保野生动物种群的长期生存能力，同时也有助于可持续捕猎—这本身就是一种保护工具。