In the far north of our planet, lie vast frozen lands of snow-covered forests and open tundra.
在我们这颗星球的远北地区，有着广袤的冰冻大地，积雪覆盖的森林与开阔无边的冻原。
During the months to come, they will be transformed by the greatest seasonal changes on earth.
在往后的几个月，将因地球上最壮观的季节变换而彻底改观。
But now, in midwinter, conditions are so hostile that life seems all but impossible.
但在此刻的隆冬时节，环境实在太严峻，生命似乎不可能在此出现。
But... not so. In this world of extremes, animals must go to extraordinary lengths to survive.
但...并非如此。在这个极端世界里，动物们都必须费尽心力才得以生存。
February, northern Canada. The harsh winter has brought together an extended family of wolves.
二月，加拿大北部。严冬让一群狼族大家庭聚在一起。
But this is no ordinary pack. There are 25 of them.
但这可不是普通的狼群。总共有25只。
A super-pack, one of the largest ever recorded.
一个超级狼群，史上被记录到最大的一群。
They're ravenously hungry. They may have walked over 150 miles since they last had a meal.
它们饥肠辘辘。距离上次进食可能已经走了150英里。

But now, at last, the lead male and female have picked up a trail.
然而现在领头狼夫妇总算嗅到踪迹。
It's been left by the only substantial prey there is here at this time of year... Bison.
是由这个时节唯一体型够大的猎物所留下...野牛。
They're formidable animals, not easy to attack.
它们是令人望之生畏的动物，不是易攻击的目标。
The bulls are ten times the size of a wolf.
公牛的体型是狼的十倍。
And they have horns with which they could rip any attacker to pieces.
而且双角足以将任何进犯者撕成碎片。
Gathered together and on guard, they appear invulnerable.
牛群齐聚戒备，似乎全无弱点。
The wolf pack's only chance... is to try and break up the group and isolate one of them.
狼群的唯一机会...就是试着打散群体，孤立其中一只。
To do that, they will have to work as a team and try to start a stampede.
为此，它们必须团队合作，试着引发奔逃。