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

行星地球5----沙漠

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 mid-winter 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 1 0 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.|冬季是交配时节

This extraordinary performance is a male Bactrian camel's way|这种奇怪的表演是公双峰驼

of attracting the attention of a passing female.|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 1 ,000 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 is 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 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.|赤裸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 heavy 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, swirl 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 seas 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 are being inexorably chiselled 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, 1 00 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|风的无情力量

ensures that the face of a desert is continually changing.|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 the 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 are 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 onto 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 heatstroke.|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

(CR0AKING)

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 a 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,|可是水分在晚上也会损耗

has to be replaced sometime, somehow.|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 50 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 would 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 are 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

[英学网] - 原创中英对照双语影视 视频英语学习网|www.EngXue.com

At the same time, wind blowing onto 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 lifesavers 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|因此这个狭长地带实际上是 阿塔卡马沙漠中

where life can exist.|唯一的生命绿洲

And 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 dried 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

(THUNDER RUMBLING)

After a rainstorm|暴风雨过后

the saguaro's long, shallow root system sucks up the water|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 that|不过这片沙漠很大

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 though 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|古老的河流冲开岩壁

steadily widened their canyons|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 truly exhausting.|高温下的战斗确实很耗费体力

(PANTING)

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 a 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|它们一起紧跟着它

as he travels across this desert|穿越沙漠

searching for food 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|非洲南部的这些岩缝中

contain the highest density of lizards in the world.|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 multicoloured 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, black fly 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 around, 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|在远离这些急流的地方

flat lizard populations are found in much smaller numbers.|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|那么在地球上，如此巨大的植食动物是如何

survive in a place apparently totally devoid of vegetation?|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 hopeless.|有时这个愿望看起来根本不可能实现

[英学网] - 原创中英对照双语影视 视频英语学习网|www.EngXue.com

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 savannah country, huge herds of game 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|这一举措在这个资源

that can make all the difference in a place of serious shortages.|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 1 00 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 temporarily.|水坑里暂时填满了水

Elsewhere in Africa elephants drink everyday|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|意味着沙漠里的大象

once every four or five days.|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 the 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|但就是这些短暂的日子使它们

that make it possible to live in deserts the year round.|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|一场大雨使得在地下沉睡了30多年的种子

to burst into life.|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|地球上再也没有其它物种

that responds as quickly and as dramatically to the good times|能像沙漠蝗那样迅速而又戏剧性地

as the desert locust.|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|随着风向迁徙意味着

they're always heading toward areas of low pressure.|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|从而形成巨大的灾害，

several billion strong and as much as 40 miles wide.|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

0nce the food has gone|待到食物耗尽之时

the steady roar of a billion beating locust wings will once again|无数蝗虫拍打翅膀时的喧哗将不复存在

be replaced by nothing more than the sound of the desert wind.|再次取代它的只是沙漠中呼啸的风声