Hunting regulations in Sweden prohibit killing brown bear mothers in company of cubs—causing mama bears to care for their young longer. Jason G. Goldman reports.

瑞典的狩猎规定禁止杀死正在哺育幼崽的熊妈妈，导致熊妈妈延长照顾幼崽的时间。贾森·G·戈德曼报道。

撰文播音：贾森·G·戈德曼（Jason G. Goldman）

翻译：邱燕宁

审校：张清越

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.

在北美洲，许多常见的野生动物，如野生火鸡或白尾鹿，都是通过猎人们发起的保护努力而从近乎灭绝的状态中恢复过来的。与此同时，在非洲，一些最具魅力的物种正在被猎杀以致濒临灭绝。不过狩猎行为对动物会有比这些更加微妙的影响。

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 life cycles. 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.

以在美国被称为灰熊的棕熊为例，当像棕熊这样的大型哺乳动物被猎杀时，进化可能会加快个体生命周期。也就是说，为了在被枪击之前成功地繁殖下一代，棕熊可能会在更年轻的年龄繁殖幼崽。这种改变也允许他们在一生中繁殖更多次。但这可能并不是猎杀行为带来的唯一反应。

"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."

“在瑞典分布的棕熊种群已经被监测了大约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她们的繁殖策略。他们观察到现在雌性棕熊会延长抚育幼崽的时间。”

University of Sherbrooke biologist Joanie Van de Walle.

舍布鲁克大学生物学家Joanie Van de Walle。

"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."

“通常雌性棕熊一月份在巢穴里繁殖小熊……但有些雌性，并不是在一年半之后给它们的幼崽断奶，而是继续多照顾它们一年。”

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

所以这一种群里的一些棕熊妈妈花更多的时间照顾幼崽，而不是更少的时间。

"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."

“我们发现，自2005以来，抚育幼崽时长达到两年半的雌性比例急剧增加。现在，大约有36%的雌性使用了这种策略，而在2005之前，只有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. [Joanie Van de Walle et al., Hunting regulation favors slow life histories in a large carnivore.]

但是增加的抚育投资是有代价的：花更多的时间和幼崽在一起，也就意味着母亲需要等更长时间才能进行下一次繁殖。进化似乎是在权衡之后选择了一个折中点：减少后代的数量，但投入更多的精力照料它们。这项发现发表在Nature Communications.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定。法律禁止杀害正在哺育幼崽的雌性棕熊。因此，那些碰巧给予了幼崽额外母性关怀的雌性不会受到枪击——这也给了孩子们保护和营养上的保证。

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的狩猎规则会如何给野生动物带来不同的结果。这种知识有助于野生动物管理者保障野生动物种群的长期生存能力，同时也增进了可持续性狩猎——这本身也是一种保护工具。