In larger mountain chains, the quest for food can become even more demanding.
在比较大的山脉，寻找食物的旅程可能来得更加困难。
The andes in South America. The longest range on earth.
南美的安地斯山脉。地球上最长的山脉。
It stretches for over 4,500 miles down towards the antarctic.
它往下方的南极延伸超过4500英里。
At its southernmost end, the sun remains so low in the sky that it brings little warmth,
在它的最南端，太阳维持在天空很低的角度，只带来很少的温暖，
and temperatures regularly drop below freezing.
温度通常低于冰点。
In winter, the land is shrouded in darkness for almost 15 hours a day.
在冬天，一天有大约15小时的时间，是大地笼罩在黑暗之中的。
Here, a predator has to hunt when it's so dark that only a thermal camera can make its activities visible to our eyes. The puma.
在这里，掠食者必须在很暗的时候狩猎，只有热成像摄影机能让我们的眼睛看到它的活动。美洲狮。
This one-year-old female faces a daunting prospect.
这只一岁大的母狮，面临着一个令人气馁的前景。

She has just left her mother and become independent at the most demanding time of the year, when prey is at its most scarce.
它才刚离开母亲出来独立，就赶上了一年中最艰巨的时期--猎物最稀少的时期。
The only substantial targets are a kind of llama. Guanaco.
唯一显着的目标是骆马的一种。原驼。
An adult stands one-and-a-half metres tall and is twice the puma's weight.
一只成年原驼高1.5米，体重是美洲狮的两倍。
This female, however, has one advantage -- excellent night vision.
然而这只母狮有一项优势，绝佳的夜视能力。
If the youngster can get within five metres of a guanaco, she has a chance of success.
如果年轻母狮能接近到原驼的五米范围内，它就有机会能成功。
But the guanaco do have a very acute sense of smell and excellent hearing.
但原驼有很灵敏的嗅觉和极佳的听力。
After six hours of patient stalking from downwind, the puma is finally within striking distance.
在下风处耐心地跟踪长达六小时后，美洲狮终于进入了攻击范围内。