科学美国人60秒 SSS 狩猎规则改变了熊妈妈的照顾事项

Hunting Rules Have Changed Mama Bear Care

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 1. But hunting can also have impacts that are far more subtle.

在北美，经常遇到的许多小动物——比如野生火鸡或白尾鹿——通过猎人带来的保护措施，从近乎遗忘中使得物种恢复过来。与此同时，在非洲，一些最具魅力的物种，现在正在遭受灭绝。但是狩猎也会产生更微妙的影响。

Take the brown bear, known here in the U.S. as the grizzly 2. When large mammals like grizzlies 3 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 4 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.

以在美国称为灰熊的棕熊为例。当像灰熊这样的大型哺乳动物被猎杀时，进化可能会选择更快的生命周期。也就是说，为了在他们冒险之前成功克隆出来，熊可能会在更年轻的时候，开始拥有并抚育幼崽。这一变化也使他们能够，在整个生命中重现更多次。但这不是被猎杀的唯一可能的反应。

"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."University of Sherbrooke biologist Joanie Van de Walle.

“瑞典的棕熊数量已经监测了大约30年，斯堪的纳维亚的研究人员已经注意到，雌性棕熊开始改变他们的繁殖策略，他们会观察到，现在雌性棕熊会抚育更长时间的幼崽。”布鲁克大学的生物学家Joanie Van de Walle说。

"Usually females give birth in January while in their den 5? But some females, rather than weaning their cubs after one year and a half, continue to care for them for an extra year."

“通常雌性棕熊会在一月份时分娩，但在一年半之内，但一些雌性棕熊，不是在一年半后，让他们的幼仔断奶，而是继续照顾他们一年多。”

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

所以，这群棕熊中的一些棕熊妈妈，开始花更多的时间，而不是更少的时间，来照顾他们的幼崽。

"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 6, whereas before 2005, it was about only 7 percent or so."

“我们已经看到，自2005年以来，抚育幼崽长达两年半的雌性棕熊比例急剧增加，现在约有36%的雌性棕熊使用这种策略，而在2005年之前，这一比例仅为7%。”

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.

但是，增加投资的代价是：花更多的时间与幼仔呆在一起，雌性棕熊再次繁殖需要更长的时间。这看起来好像进化在权衡上得到了解决：后代少了，但在他们在照顾后代中投入了更多的精力。这一研究发表在《自然沟通杂志》上。

And the change can be traced to Swedish hunting regulations. The law prohibits killing 7 females if they are accompanied by cubs. So females that happen to have the urge for extra maternal 8 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法规。 法律禁止杀害雌性棕熊，如果他们在陪伴幼崽。因此，那些碰巧得到额外护理的雌性棕熊不会被射杀——这也给了小棕熊以保护和营养需要。

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 9 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，可能导致野生动物的不同结果。这种知识有助于野生动物管理者，确保野生动物种群的长期生存能力，同时也可以进行可持续的狩猎——这本身也可以成为一种保护工具。