Encompassing an extreme range of climates, Scandinavia is made up of five countries spanning much of the northern hemisphere.
斯堪的纳维亚有多种极端气候，它包含五个国家，覆盖大部北半球。
It is home to a diverse array of animals uniquely adapted to life in this ice scarred region.
这里是多种动物的家园，只有它们能适应这冰雪雕琢的世界。
Large herds of reindeer are only seasonal visitors to the treeless expanse of tundra.
大批的驯鹿只是季节性地到访这没有树木的广阔苔原。
They cannot survive winter here, so every autumn they migrate south to the shelter of the forests.
因无法在这里过冬，所以每年秋季它们都要向南方的森林里迁徙。
It's a busy time for breeding males. Migration is at the same time as the rut.
对处于繁殖期的雄性来说这是一个繁忙的季节。迁徙和发情的时间重叠。
For more than three weeks, the males do nothing but fight and mate while keeping on the move.
有三个多星期，雄性在行进过程中只管争斗和交配。
They live entirely off their fat reserves.
它们完全依靠体内存储的脂肪生存。
The herds travel as much as 50 kilometers every day.
鹿群每天要行进五十公里。
They must leave before extreme conditions shut the door.
它们得在恶劣天气到来之前离开。

Behind them, winter closes in fast.
它们身后，冬天迅速地逼近。
Temperatures plunge, often reaching minus 40 degrees Celsius.
温度急转直下，经常达到摄氏零下四十度。
Deep snows cover the land, and the sun disappears below the horizon for two months.
深深的积雪覆盖大地，太阳将消失在地平线之下达两个月之久。
The only break to winter darkness is celestial spectacle, the aurora borealis.
黑暗冬季里唯一的亮光就是这种天文奇观，北极光。