- A third of the land on our planet is desert.
我们星球上1/3的陆地是沙漠 - These great scars on the face of the Earth appear to be lifeless,
这些地球脸上的大伤疤看似毫无生机 - but surprisingly none are.
然而令人吃惊的是并非如此 - In all of them life manages somehow to keep a precarious hold.
在所有沙漠中 生命总能以某些方式闪现 - Not all deserts are hot.
沙漠并非都是炎热的 - Fifty-mile-an-hour winds blowing in from Siberia
西伯利亚的寒风以50英里的时速 - bring snow to the Gobi Desert in Mongolia.
夹杂着风雪横扫蒙古戈壁沙漠 - From a summer high of 50 degrees centigrade
虽然夏季气温高达50℃ - the temperature in midwinter can drop to minus 40,
但是到了冬至却能降至零下40℃ - making this one of the harshest deserts of all.
使得这里成为一片最荒凉的沙漠 - Few animals can survive these extreme changes.
只有少许动物能适应 这种极端的气候变化 - Wild Bactrian camels,
野双峰驼 - one of the rarest mammals on the planet.
一种地球上最稀有的哺乳动物 - And perhaps the hardiest.
可能也是最坚韧的动物 - Their biggest problem is the lack of water,
它们最大的困难莫过于缺水 - particularly now, in winter,
尤其是现在——冬天 - when the little there is is locked up as ice.
那里仅有的一点水也结成了冰 - Surprisingly, snow here never melts.
奇怪的是 这里的雪永远都不会融化 - The air is just too cold and too dry for it to do so.
又冷又干的空气使它们无法解冻 - The sun's rays turn it straight into vapour.
阳光把它们直接变成了水蒸气 - It evaporates.
它们升华了 - But it is the only source of water,
可是这是唯一的水源 - so Bactrian camels eat it.
所以双峰驼只能吃雪 - Elsewhere in the world
在世界上其它地方 - a camel at a waterhole can drink as much as 200 litres during a single visit.
一只骆驼找到水坑后 能一次喝下200升水 - Here the strategy is to take little and often.
但在这里的饮水策略却是少而频繁 - And with good reason,
这当然有充分的理由 - for filling the stomach with snow could be fatal.
因为肚子里装满雪将是致命的 - The camels must limit themselves to the equivalent of just 10 litres a day.
骆驼必须限定自己 每天只能吃10升左右的雪 - Winter is the time for breeding.
冬季是交配繁殖的时节 - This extraordinary performance is a male Bactrian camel's way of attracting the attention of a passing female.
这种奇怪的表演是公双峰驼 吸引路过的母骆驼的一种方式 - In summer the camels can't stray far from waterholes.
在夏天 骆驼不能远离水坑 - But now, with mouthfuls of snow lying everywhere
可是现在 遍地都是唾手可得的雪 - they can travel widely in search of mates.
它们便能长途跋涉寻找配偶 - Today less than a thousand of these desert specialists remain in the wild.
今天 这些沙漠专家的 野生数量已不足1000只 - The Gobi, hostile though it is, is their last stronghold.
戈壁尽管环境险恶 却是它们最后的据点 - There's no other desert quite like the Gobi,
别的沙漠都和戈壁不太一样 - but why is this place a desert?
为什么这里会成为沙漠呢 - There is one simple and massive cause -
这里有一个简单而又重要的原因 - the Himalayas.
喜马拉雅山脉 - Clouds blowing from the south hit this gigantic barrier.
从南方过来的暖湿气流 撞上了这面巨大的屏障 - As they're forced upwards
在被迫抬升的过程中 - so they empty their moisture on the mountain slopes,
水汽在山坡上逐渐凝结 - leaving little for the land on the other side.
只有一小部分到达另一边的土地 - From the space deserts are very conspicuous.
从太空中看 沙漠非常显眼 - Dunes of sand hundreds of miles long streak their surface.
绵延数百英里的沙丘像是一条条皱边花纹 - With no cloak of vegetation to conceal them
由于没有植被覆盖 - strange formations are exposed in the naked rock.
裸露的岩石显露出奇特的造型 - Africa's Sahara is the largest desert of all.
非洲的撒哈拉沙漠是世界上最大的沙漠 - It's the size of the United States
它的面积相当于美国 - and the biggest source of sand and dust in the entire world.
也是全世界最大的沙尘源 - Sandstorms like these appear without warning
如此巨大的沙暴出现时毫无征兆 - and reduce visibility for days over areas the size of Britain.
所到之处能见度骤降为零 几天内横扫的地区比英国还大 - Dromedaries, single-humped camels, take these storms in their stride.
单峰驼——只有一个肉峰的骆驼 顶着沙暴大步行走 - The heaviest sand rises only a few metres above the ground,
最重的沙子只能离开地面几米 - but the dust can be blown 5,000 metres up into the sky.
但是尘埃却能被吹上5000多米高的天空 - The ferocious wind, armed with grains of sand,
夹杂着沙粒的强风 - is the agent that shapes all deserts.
塑造了各种沙漠地形 - Reptiles have armoured scaly skins that protect them from the stinging grains.
爬行动物的皮肤覆盖着鳞甲 能抵御刺痛的沙粒 - For insects the bombardment can be very severe indeed.
而昆虫则得遭受猛烈“炮火”的轰击 - The only escape is below the surface.
唯一的藏身之处当然是在沙子下面 - As the winds rise and fall, swallow and eddy
随着风的起落、侵蚀和旋绕 - so they pile the sand into dunes.
沙子被堆成了一座座沙丘 - These sand scenes can be hundreds of miles across.
这些沙漠布景可宽达数百英里 - In Namibia the winds have built some of the biggest dunes in the world.
在纳米比亚 风塑造了 一些世界上最大的沙丘 - Star dunes like these can be 300 metres high.
这些巨型沙丘高达300多米 - Grains, swept up the flanks, are blown off the crests of the ridges
斜坡上吹起的沙粒 在沙丘顶部的边棱处飞扬 - so it's only the tops that are moving.
所以沙丘移动的部分只是顶部 - The main body of these dunes may not have shifted for 5,000 years.
这些沙丘的主体 可能已有5000多年未曾移动 - Few rocks can resist the continuous blast of the sand carrying wind.
岩石很难抵挡风沙持续不断的摧残 - These outcrops are standing in Egypt's White Desert.
这些石头如今矗立在埃及的白色沙漠中 - But they will not do so for much longer.
但它们也坚持不了多久 - They're being inexorably chiseled away and turned into more sand.
它们正被无情地凿碎 变成更多的沙粒 - Now lumps of heavily eroded rocks have been marooned in a sea of sand.
现在 这些严重侵蚀的石块 已被放逐在沙海之中 - These jagged pyramids a hundred metres tall
这些高达100多米的锯齿般的石锥 - were once part of a continuous rocky plateau.
曾经是一整块岩石高地的一部分 - The blasting sand will eventually eliminate them altogether.
强悍的风沙最终将使它们完全消失 - The relentless power of the wind ensures that the face of a desert is continually changing.
风的无情力量总是使沙漠的面貌不断改变 - But there is one constant presence -
但是有一样东西永远都会存在 - the desert sun.
沙漠的太阳 - The sun's heat and power to evaporate water
太阳的热力使水蒸发 - has had a profound effect on the bodies and habits of everything that lives here.
这对所有生活在这里的动物的 身体和习性都有极其深远的影响 - This sun potentially is a killer.
在这里 太阳将会成为杀手 - And the red kangaroos must acknowledge that.
红大袋鼠必须意识到这一点 - Right now, while the sun is low,
此时 太阳还未升起 - there's no immediate cause for concern.
并没有直接危及到生命 - But this situation won't last long.
但是这种情况不会持续多久 - Australia is the world's most arid continent with blistering daytime temperatures.
澳大利亚是世界上最干旱的大陆 整个白天酷热难当 - Every hour the temperature rises by five degrees centigrade.
每过一小时 气温就将升高5℃ - Soon the heat will reach a critical point.
热度很快就会达到临界点 - Any kangaroo out in the open is in serious danger of overheating.
任何一只呆在外面的袋鼠 都将面临中暑的威胁 - In the full sun the temperature on the ground soars to 70 degrees.
待到阳光最毒辣之时 地面温度已升高至70℃ - By midday the radiation is so intense they must take shelter.
到了正午 太阳的炙焰 迫使它们不得不寻找庇荫处 - In the shade they're shielded from much of the sun's energy
在树荫下 它们虽然避开了太阳的能量 - but their body temperature can still rise.
但它们的体温仍在升高 - So they lick saliva on to their forearms
所以它们将唾液抹在前臂上 - where there is a network of blood vessels close to the surface of the skin
那里的血管网比较贴近皮肤表层 - and, as the saliva evaporates, their blood is cooled.
因此 当唾液蒸发时 血液也能得到冷却 - This thermal image shows just how effective the process is.
这幅热影像能证明这种方法非常有效 - The blue areas on the body are the cooler parts.
身上蓝色的部分是较冷的部位 - As the saliva dries it has to be replaced
唾液干了之后还得重新抹上 - and this is a real drain on the kangaroo's body fluids.
袋鼠真正排放出去的体液也就是这些 - Even in the shade the earth is baking hot
即使是在树荫下 土地照样被烤得火热 - so the kangaroos dig away the warmed topsoil
于是袋鼠刨去灼烫的表层沙土 - to get at the cooler ground beneath.
贴近下面较冷的地面 - By staying in the shade and licking to control their body temperature
通过呆在树荫下 并利用舔唾液的方法控制体温 - kangaroos manage to get through the hottest part of the day
袋鼠便能熬过一天中最热的时段 - without heat stroke.
而不至于中暑 - But for the majority of desert animals
但是对于大多数沙漠动物来说 - this strategy would not be enough for survival.
光凭这些手段还不足以在此生存 - The extraordinary ears of the fennec foxes of Africa radiate heat
非洲的耳廓狐长有奇特的大耳 它们能散发热量 - but the animals have another way of keeping cool.
不过动物也有其它保持凉爽的方法 - They spend their days underground
它们白天呆在地下 - and only emerge at sunset.
直到日落之后才会出现 - Darkness brings huge changes.
夜晚的情况变得很不一样 - In the Sahara the temperature can drop as much as 30 degrees during the night,
在撒哈拉沙漠中 晚上的气温会下降整整30℃ - so it's cool enough to allow these desert fox cubs to play.
在如此凉爽的时候 小耳廓狐也能尽情玩耍 - All sorts of creatures now appear
此时各种各样的动物都开始现身 - including some really unexpected ones.
包括一些意想不到的动物 - Toads have permeable skins
蟾蜍长着透水的皮肤 - and would quickly die from desiccation out in the daytime heat.
若是在白天的高温下 它们很快就会因为脱水而死 - It's only now that they can leave shelter.
所以只有到了晚上它们才能离开庇护所 - The same is true for scorpions,
蝎子也是同样的情况 - even though their shells are actually watertight.
尽管它们的外壳其实并不透水 - In fact, most small desert creatures are nocturnal.
事实上 大多数小型沙漠动物 都是夜行动物 - so it's only now that you can judge just how much life there can be in the desert.
所以只有此时你才能判断 沙漠中究竟有多少生物 - But moisture, lost even at night, has to be replaced sometime somehow
可是水分在晚上也会损耗 必须在什么时候想办法补充 - and that problem dominates the lives of all desert dwellers.
这一问题支配着所有沙漠动物的生活 - The Atacama in Chile.
智利的阿塔卡马沙漠 - This is the driest desert in the world.
这里是世界上最干旱的沙漠 - Some parts may not see rain for fifty years
有的地方可能连续5年不会下一滴雨 - and with such a record
既然有了这一纪录 - you'd expect the place to be completely barren.
不难想象这个地方定是彻底的荒芜 - These are South America's camels, guanacos.
这些是南美洲的骆驼——原驼 - They're very good at conserving moisture
它们非常善于保存水分 - but they nonetheless need a regular supply of water.
但它们仍须定期补充水 - They get it partly from cactus flowers
其中一部分水取自仙人掌花 - but that explanation raises another question.
但这里又牵扯出另一个问题 - How do the cacti survive without rain?
仙人掌为何能在这个无雨地带生存 - Hot winds suck all the moisture from the surface of the land.
热浪抽干了地面上所有的水分 - Clearly there must be something else that takes the place of rain.
显然 这里必须有其它东西 能代替雨水的作用 - The secret is a cold sea current that runs parallel to the land.
答案就是一股与陆地平行的寒冷洋流 - The cold water cools the moist warm air above it
冷水使得上方的暖湿气流冷却 - and that produces banks of fog.
形成一团团的雾霾 - At the same time wind blowing on to the shore sweeps the fog inland.
与此同时 吹向海岸的风将雾气带上陆地 - Before long the cacti are dripping with dew.
不久之后 雾凝结成了露水 - The fog is so regular
雾经常会出现 - that moisture loving lichens are able to grow on the cacti
就连喜湿的地衣也能在仙人掌上生长 - and they absorb liquid like a sponge.
它们像海绵一样吸收着水汽 - In the land of almost no rain
在一个几乎没有雨的地方 - these precious drops are life-savers for many different creatures.
这些宝贵的水滴是许多动物的救命物资 - Further inland the air remains so warm that its moisture does not condense
在更远的内陆地区 空气一直十分灼热 水汽无法凝结 - so this slender strip of desert is virtually the only part of the Atacama where life can exist.
因此这个狭长地带实际上是 阿塔卡马沙漠中唯一的生命绿洲 - Without the fog,
如果没有雾 - this land, too, would be empty.
这片土地也将成为不毛之地 - The guanacos make the most of the dew
原驼尽量舔吮露水 - but it will not remain for long.
因为它们不会保留多久 - In an hour or two the sun will have burnt it off
1～2小时后 太阳将使它们蒸发 - and dry the surface of the cacti.
仙人掌表面将回复干燥 - The Sonoran desert in Arizona is not quite so dry as the Atacama -
亚利桑那州的索诺兰沙漠 并不像阿塔卡马沙漠那样干旱 - some rain does fall.
这里有时会下一些雨 - But it is infrequent
可是降雨次数很少 - and when it does arrive
一旦雨水到来 - animals and plants have to be ready to make the most of it.
所有动植物都必须 做好准备尽量地利用它们 - And it's coming.
要下雨了 - When the summer monsoon blows in
当夏季季风吹来时 - the giant saguaros, one of the biggest of all cacti,
巨大的弁庆柱 ——一种世界上最大的仙人掌 - are ready to take full advantage of it.
准备充分利用雨水 - After a rainstorm the saguaro's long shallow root system sucks up the water
暴风雨过后 弁庆柱 用又长又浅的根系吸收水分 - and the pleats on its trunk enable it to expand rapidly.
茎上的皱褶使之能迅速膨胀 - When full, a saguaro stem can store up to five tonnes of water
吸饱水后 弁庆柱的茎干中 已储存了5吨左右的水 - and that's enough to see it through many months of drought.
这足以帮助它们度过几个月的旱季 - The trunks of these huge plants provide homes for the gila woodpecker.
这些立柱般的巨型植物 为橙腰啄木鸟提供了住所 - But birds are not the only animals to benefit from the presence of the cacti.
不过鸟并非唯一从仙人掌那里 获得好处的动物 - During four weeks of the summer
在夏季的4个星期里 - the saguaros bloom at night to attract visitors.
弁庆柱在晚上开花 吸引了不少拜访者 - The pollen and nectar with which these flowers are loaded
这些花中装满了花粉和花蜜 - attract long-nosed and long-tongued bats.
吸引了长鼻蝠和长舌蝠 - The bats left Mexico a few days earlier to escape the heat of summer
蝙蝠数日前离开墨西哥以躲避酷暑 - and are on their way north to the southern United States.
正向北飞往美国南部 - To get there, they have to cross the Sonoran desert.
要想到达那里 它们必须穿越索诺兰沙漠 - But the desert is so big
不过这片沙漠很大 - that for most of the year they would be unable to cross it.
它们一年中大部分时间都无法穿越这里 - Now, with the saguaro in bloom,
现在 有了正在开花的弁庆柱 - they can refuel on the way.
它们便能在旅途中得到休整 - So the saguaro's success in developing a way to store water
看来弁庆柱进化出的 这种成功的储水方式 - is now crucial to most of the animals that live or even travel through this land.
如今已关系到大部分 在此生活和旅行的动物 - The scarcity of rain determined the shape of this icon of the desert
缺少雨水的环境塑造了这些沙漠中的图标 - but water, scarce thought it is, has also, like the wind, shaped the land itself.
尽管水很少 但它也和风一样 造就了各种地形 - In the deserts of Utah
在犹他州的沙漠中 - ancient rivers flowing across sandstone country steadily widen their canyons
古老的河流冲开岩壁 不断拓宽这些峡谷 - until now the land between them has been reduced to spires and pinnacles.
直到把其间的土地削凿成 今天这样的尖峰和石塔 - With little or no soil to retain the water on the surface of the land
由于几乎没有土壤保留地表水分 - life here is scarce indeed.
这里的生物极其稀少 - And when resources are limited,
当资源有限的时候 - conflict is never far away.
冲突自然不可避免 - These are Nubian ibex
这些是努比亚羱羊 - and they are squaring up for a duel.
它们正摆好架势准备激战 - And when trouble starts,
冲突一旦爆发 - a smart ibex knows that the best thing to do is to gain higher ground.
聪明的羱羊很清楚 最好的战术就是占领制高点 - These are actually subordinate male ibex,
这些其实是次级别的公羱羊 - but their fights are nonetheless serious.
但它们的战斗依然十分激烈 - Losing one might mean never getting the chance to breed ever.
失败一次或许意味着将永远失去生育权 - When competitors are evenly matched as they are here,
同级别的参赛者在此公平竞争 - duels can last for an hour.
决斗会持续一小时左右 - In this heat the effort is trully exhausting.
高温下的战斗确实很耗费体力 - But victory here will gain important ranking points on a male's way to the top.
但是这里的获胜者会获得重要的排名 一步步到达公羊排行榜的第一位 - There's so much at stake
这类决斗非常危险 - that not all play fair.
而且并不总是公平的 - The battle has produced the winner,
这场战斗已经分出了胜负 - but the ultimate prize is not his yet.
但是最后的奖品仍然不属于它 - That currently belongs to the dominant male ibex.
它通常属于拥有统治权的公羊 - His rank earns him the loyalty of a harem of females
它的地位为它赢得了一群忠诚的母羊 - and they follow him closely as he travels across this desert
它们一起紧跟着它穿越沙漠 - searching for foof and water.
寻找水和食物 - He doesn't have to waste time looking for mates -
它不必浪费时间寻找配偶 - they're his for the taking,
它们都是它的妻子 - so he can concentrate with them on keeping fit and healthy.
所以它要做的只是保证它们健康精壮 - Lizards are desert specialists.
蜥蜴是沙漠专家 - But here, their numbers are extraordinary.
在这里 它们的数量多得惊人 - These crevices in South Africa contain the highest density of lizards in the world.
非洲南部的这些岩缝中 容纳着世界上最大的蜥蜴群 - They're called flat lizards for obvious reasons,
它们叫做扁石蜥——因为显而易见的原因 - and they flaunt their multi-coloured bellies in territorial disputes.
它们炫耀自己五颜六色的腹部 是为了争夺领地 - He's made his point,
它赢了 - and now it's time to find some food.
现在该是寻找食物的时候了 - As the day warms up,
随着白天气温的升高 - the lizards move away from their cracks
蜥蜴离开它们藏身的岩缝 - and head down to the bottom of the gorge.
奔向峡谷底部 - Their goal is the river.
它们的目标是这条小河 - There is no food at the edge,
河边没有一点食物 - but this desert river holds a secret.
但是这条沙漠河流却藏着一个秘密 - Each day blackfly rise from turbulent stretches of the river.
每天 成千上万的蚋从奔腾的河水中羽化 - This is what the lizards have come for.
这就是蜥蜴到此的目的 - The black fly never land,
蚋不会降落 - so the lizards have to leap for their food.
所以蜥蜴必须跳起来捕食 - In one day each of these acrobatic little lizards may catch 50 flies.
每只身怀绝技的小蜥蜴 一天能吃掉50多只小虫 - There are plenty of flies to go round, even with hundreds of lizards competing for them.
尽管已有几百只蜥蜴在此捕猎 这里仍聚集着无数飞虫 - Away from these rapids flat lizard populations are found much smaller numbers.
在远离这些急流的地方 扁石蜥的数量则要少得多 - But here one unusual abundance has produced another.
但在这里 一种特别的资源 带动了另一物种的兴起 - Deserts are created by the lack of water,
沙漠的形成是因为缺少水 - but what actually kills animals here is not heat or thirst,
可是这里杀死动物的 真正原因并非炎热和缺水 - but lack of food.
而是缺少食物 - So how on earth does a plant-eater this size survive in a place apparently totally devoid of vegetation?
那么在地球上 如此巨大的植食动物是如何 在这个寸草不生的地方生存的呢 - Elephants in Namibia are the toughest in Africa.
纳米比亚的大象是非洲最能吃苦的动物 - And they need to be.
它们必须如此 - What little food exists is so dispersed
仅有的少量食物也非常分散 - that these elephants walk up to 50 miles a day
所以这些大象每天得走上50英里 - as they travel up the dry river channels searching for something to eat.
沿着干涸的河床搜寻一些可以吃的东西 - At times the task looks truly helpless.
有时这个愿望看起来根本不可能实现 - Elephants may seem out of place in this landscape,
大象似乎不属于有这种地形的地方 - but they're not the only ones.
但它们并非唯一意外的物种 - Amazingly, lions live here, too.
奇怪的是 狮子也生活在这里 - In savanah country huge herds of games support prides containing 20 lions or more.
热带大草原的竞争促使鼎盛的 狮群数量达到20只 甚至更多 - But to live here lions have had to change their habits -
而若想在此生存 狮子必须改变它们的习性 - prides are much smaller
狮群规模小了很多 - and their home ranges are very much bigger.
但家族的疆土面积却大大增加 - And there's an added problem -
这里还有另一个问题 - their food is always on the move.
它们的食物总是在移动 - Like the elephants,
和大象一样 - the lions must travel great distances to find enough to live on.
狮子也必须长途跋涉 寻找生存所需的食物 - But lions can't go everywhere -
可是狮子并不是什么地方都能去的 - they won't attempt to cross this field of sand dunes
它们不会试着爬过一座沙丘 - and the oryx know it.
长角羚很清楚这一点 - The lions must wait for the oryx to leave the safety of the dunes,
狮子必须耐心等待 长角羚离开安全的沙丘 - which eventually they must to find food and water.
因为它们最后总得寻找食物和水 - And then the lions will ambush them.
介时狮子就能伏击它们 - The elephants have found some of their favourite food.
大象找到了一些它们最喜欢吃的食物 - Grasses are the staple diet of all elephants,
草是所有大象的主食 - but this herd concentrates on digging up the roots,
但这群象却忙着挖掘草根 - which have more nutrition and moisture than the stems.
因为草根中的营养和水分比茎干多得多 - It's the sort of behaviour that can make all the difference in a place of serious shortages.
这一举措在这个资源 严重匮乏的地方显得极为重要 - Yet all this can change in an instant.
然而所有这一切即刻就将发生改变 - The fortunes of many deserts are ruled by distant rains.
许多沙漠的命运都由远方的雨水决定 - This water fell as rain in mountains more than a hundred miles away.
这些水来自100英里之外的山地降雨 - It's known as a flash flood
它叫做“瞬时洪水” - and called that because the water may run for just a single day.
之所以这么叫是因为 这些水可能仅仅流淌一天左右 - It's an event that only happens once or twice a year at the most.
而且一年最多也只发生1～2次 - The sandy riverbed acts like a giant strip of blotting paper
布满沙子的河床像是一张巨大的吸水纸 - sucking up the water as soon as it appears.
水一边流淌一边被它吸去 - But every square metre of soil moistened by this river
这里的每一寸土壤都已被河水润湿 - will increase the chances of survival for those that live here.
为生活在这里的动物们带来了生机 - Waterholes are filled temprorarily.
水坑里暂时填满了水 - Elsewhere in Africa elephants drink every day,
非洲其它地方的大象每天都会喝水 - but the lack of water here
但这里缺水的现状 - means that desert elephants can only refill their tanks once every four or five days.
意味着沙漠里的大象 只能每隔四五天喝饱一回 - Within a week the flash flood has produced a flush of green,
短短一周内 瞬时洪水浸润过的 土地上已长出了青草 - more than enough to draw the oryx out of the dunes.
远远多于从沙丘返回的长角羚的需求 - It's a rare chance for them to build up their food reserves.
这是它们仅有的积累食物储备的机会 - The flood has made life easier for the lions, too.
洪水也让狮子过上了好日子 - The flesh of this oryx will keep the family going for a week at the most.
这只长角羚的肉最多 能维持整个家族一星期左右 - But for a while the hunting will be easier, now that river channel has turned green.
此时 狩猎暂时变得容易许多 河道也穿上了一件绿装 - The good times for lions and oryx are brief,
狮子和长角羚的美好时光十分短暂 - but these are the short moments that make it possible to live in deserts the year round.
但就是这些短暂的日子使它们 得以全年在沙漠中生活 - Death Valley is the hottest place on Earth.
死亡谷是地球上最热的地方 - Yet even this furnace can be transformed by water.
然而这个“火炉”也会因为水而发生改变 - A single shower can enable seeds that have lain dormant for 30 years or more to burst into life.
一场大雨使得在地下沉睡了30多年的 种子迸发出生命的活力 - And there hasn't been a bloom like this one for a century.
这里已有一个世纪 没有像现在这样开满鲜花 - The periods of boom in Death Valley are short.
死亡谷中的花期很短 - but they're just frequent enough to keep life ticking over.
但它们发生的次数 足以保证生命长盛不衰 - A sudden flush of vegetation is what every desert dweller waits for,
植物的突然兴盛是 所有沙漠动物都盼望的事 - and when it happens they must make the most of it.
一旦发生 它们必须尽可能地利用它 - There is no other species on the planet that responds as quickly and as dramatically to the good times as the desert locust.
好日子到来时 地球上没有其它物种 能像沙漠蝗那样迅速而又戏剧性地作出反应 - Eggs that have remained in the ground for 20 years begin to hatch.
在地下埋藏了20年的虫卵开始孵化 - The young locusts are known as hoppers,
沙漠蝗的若虫是跳跃能手 - for at this stage they're flightless.
在这一阶段 它们还不能飞 - They find new feeding grounds by following the smell of sprouting grass.
它们循着萌发的草香寻找新的用餐场所 - Normally it takes four weeks for hoppers to become adults,
一般说来 若虫需要 经过4周才能变成成虫 - but when the conditions are right as now
但如果条件允许 譬如现在 - their development switches to the fast track.
它们的生长过程就会切换到快车道 - As the vegetation in one place begins to run out
当一个地方的植物即将吃光时 - the winged adults release pheromones - scent messages,
长着翅膀的成虫便释放出信息素 即一些气味信号 - which tell others in the group that they must move on.
提醒蝗群中的其它成员它们应该动身了 - And when groups merge,
蝗群合并之后 - they form a swarm.
形成了一团蝗虫云 - An adult locust eats its entire body weight every day,
成虫每天的进食量相当于自己的体重 - and a whole swarm can consume literally hundreds of tonnes of vegetation.
而整团蝗虫云能消耗掉数百吨植物 - They have to keep on moving.
它们必须不停地迁徙 - The swarm travels with the wind -
沙漠蝗御风而行 - it's the most energy-saving way of flying.
这是最省力的飞行方式 - Following the flow of wind means that they're always heading toward areas of low pressure,
随着风向迁徙意味着 它们总是飞向低压地区 - places where wind meets rain and vegetation starts to grow.
那里正是风雨交加的地方 植物定能生长 - As they fly,
在飞行过程中 - swarms join up with other swarms
一团蝗虫云也会和其它蝗虫云汇合 - to form gigantic plagues several billions strong and as much as 40 miles wide.
从而形成巨大的灾害 无数“瘟神”组成的大军绵延长达40英里 - They will consume every edible thing that lies in their path.
它们将把一路上能吃的东西 全部吃得精光 - This is one of planet Earth's greatest spectacles.
这是地球上最壮观的景象之一 - It's rarely seen on this scale
很少能看见如此大的规模 - and it won't last long.
而且也不会持续多久 - Once the food is gone,
待到食物耗尽之时 - the steady roar of a billion beating locust wings will once again be replaced by nothing more than the sound of the desert wind.
无数蝗虫拍打翅膀时的喧哗将不复存在 再次取代它的只是沙漠中呼啸的风声 - [The End]
[本集结束]
行星地球 第一季 第五集 Planet Earth S01E05 沙漠
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