After less than six weeks, the short summer is over.
过了不到六周的时间，短暂的夏季就结束了。
For the birds, the lush wetlands that attracted them here are freezing over and they must leave or face starvation.
对鸟类来说，吸引它们丰美湿地正开始结冰，它们必须离开了，否则就会挨饿。
Early snow catches up the fox and their cubs who are still too young to fend for themselves.
北极狐和幼小而无力自卫的孩子们动作稍慢就被初冬的降雪赶了上来。
Across the tundra, the reindeer are heading south.
整个苔原上，驯鹿群都在向南迁徙。
The porcupine herd, over one hundred thousand strong, now breaks up as they return towards the shelter of the forests per winter.
拥有十万之众的格兰特驯鹿如今分为几支群体，朝着每年冬季避寒的森林方向奔去。
The calves born just a few weeks ago are now strong.
几周前才出生的小鹿现在变得强壮起来。
But for the mothers, tired from the mating season, there are many dangers ahead as they set out on the two-and-a-half thousand kilometer journey. Together for the first time.
但母鹿们，还尚未从疲惫的交配期缓过神来，它们就不得不在首次一同踏上这两千五百公里征途的那一刻就面临更多的危险。
But the pressure on to keep moving, the herd is forced to take risks.
但在威胁下被迫前行，鹿群却不得不进行冒险。
Crossing a river so recently frozen can be a deadly mistake.
企图横越结冰不久的河面会是个致命的错误。
Struggling to escape from water as this cold can exhaust a reindeer in just seconds and is exactly what the wolves are waiting for.
而想从如此冰冷的河水中挣扎逃离，可能会在几秒钟内耗尽驯鹿的体力，这也正是狼群期待已久的。
But the reindeer is incredibly tough and there'll be no easy pickings for the wolf pack today.
但这头驯鹿却顽强得难以置信，看来今天狼群想轻易地捡到美餐是不太可能了。
The reindeer's annual migration is one of the most epic battles for survival on the planet.
驯鹿一年一度的大迁徙是地球上其中一幕最壮观的求生之战。
By October, this vast landscape that covers ten percent of all land on earth is once again return to a frozen desert.
到了十月，这片占地球上陆地面积百分之十的广阔土地再次成为一片冰冷的荒原。
As the tundra sun falls below the horizon for the last time this year, it will not rise again for another three months.
随着今年内太阳在苔原上最后一次落入地平线之下，它在今后三个月之内将不再升起。
