In the grasslands of Mauritania, a gazelle suffering from tuberculosis takes its last breath.
在毛里坦尼亚的草地上，一只患结核病的瞪羚呼出了它最后一口气。
Collapsing near a small pool, the animal's corpse threatens to infect the water.
它倒在了一个小水池边，尸体有感染水源的危险。
But for the desert's cleanup crew, this body isn't a problem: it's a feast.
但是对于沙漠里清洁工，这不是问题，而是美餐。
Weighing up to 10 kilograms and possessing a wingspan of nearly 3 meters, the lappet-faced vulture is the undisputed king of the carcass.
体重可达10千克，翼幅接近3米，肉垂秃鹫可以说是当之无愧的死尸之王。
This bird's powerful beak and strong neck easily tear through tough hide and muscle tissue, opening entry points for weaker vultures to dig in.
这种鸟有力的喙和强大的脖颈，能轻松地撕裂坚硬的兽皮和肌肉组织，打开了一个开口使得更弱小的秃鹫能够享用。
This colossal competition is too dangerous for the tiny Egyptian vulture.
与这种巨大的秃鹫竞争对于体型较小的埃及秃鹫来说太危险了。
With a wingspan of only 180 centimeters, this vulture migrated to Africa from his family nest in Portugal, using thermal updrafts to stay aloft for hours at a time.
埃及秃鹫翼幅仅有180厘米，它从远在葡萄牙的家迁徙来到非洲，利用上升热气流来使自己一次可以维持飞行好几个小时。
But upon arrival, he finds himself near the bottom of the pecking order.
但是一到目的地，它就发现自己在啄食顺序中几乎排名最后。
Fortunately, what he lacks in size, he makes up for in intelligence.
幸运的是，它的智慧弥补了它体型上的缺陷。
A short distance away, he spots an unguarded ostrich nest, full of immense, but impenetrable eggs.
不远处，它发现了一个没有保护的鸵鸟巢，里面全是巨大且难以穿透的鸵鸟蛋。
Using a large rock, he smashes one open for a well-earned meal -- though he'll circle back to the gazelle once the larger birds are gone.
它用一块巨石打碎了一只蛋作为一顿应得的美餐--尽管那些大鸟走后它还会绕回到瞪羚旁。
High above the commotion are Ruppell's Griffon vultures.
在空中远离这场喧闹的是黑白兀鹫。
Soaring at an altitude of over 11,000 meters, these birds fly higher than any other animal.
翱翔在海拔11,000米的高空，这些鸟比其它任何动物都飞得高。
At this height, they can't see individual carcasses. But the sight of their fellow vultures guides them to the feeding.
在这样的高度，它们看不见单个的尸体。但是它们秃鹫同胞们的身影带着他们到了有食物的地方。
Their featherless heads help them regulate the sudden rise in temperature as they descend -- and keep them clean as they tear into the decaying gazelle.
在它们下降时，没毛的头会帮助调节骤升的温度--还可以在它们撕扯腐烂的瞪羚时保持清洁。
The carcass is stripped clean in hours, well before the rotting meat infects the water supply.
瞪羚的残骸在几小时内就被吃干净了，腐烂的肉还来不及污染到水源。
And the tuberculosis doesn't stand a chance at infecting the vultures.
而结核病完全没机会感染秃鹫。
These birds have evolved the lowest gastric pH in the animal kingdom, allowing them to digest diseased carrion and waste without becoming sick.
这些秃鹫已经演化出了动物界酸碱度最低的胃酸，这使得它们可以消化病变的腐肉和排泄物而不生病。
In fact, species like the mountain-dwelling bearded vulture have stomachs so acidic, they can digest most bones in just 24 hours.
事实上，像山居的胡兀鹫有着酸性很强的胃，以至于它们可以在24小时内消化绝大多数的骨头。
This adaptation helps smaller vultures supplement their diet with dung, while larger vultures can consume diseased meat up to 3 days old.
这种适应使得体型小的秃鹫吃动物粪便来补充食物，而更大的秃鹫可以消化病死三天的腐肉。

Their acidic stomachs protect them from living animals too: their rancid vomit scares off most predators.
它们的胃酸也保护自己不受活物的威胁：它们令人作呕的呕吐物能吓跑大部分的捕食者。
These stomachs of steel are essential to removing pathogens like cholera, anthrax, and rabies from the African ecosystem.
它们钢铁般的胃对于去除非洲生态系统中的霍乱弧菌、炭疽杆菌和狂犬病毒等病原体来说十分重要。
But while vultures can easily digest natural waste, man-made chemicals are another story.
尽管秃鹫可以轻易地消化自然界的废物，人造化学试剂就是另一回事了。
Diclofenac, a common veterinary drug used to treat cattle in India, is fatal to vultures.
双氯芬酸，一种在印度常见的用于治疗家牛的兽用药，对秃鹫是致命的。
And because local religious beliefs prohibit eating beef, scavengers often consume cattle carcasses.
因为当地宗教信仰禁止吃牛肉，食腐动物经常清理家牛的残骸。
Since the 1990s, the drug, along with threats from electricity pylons and habitat loss, has contributed to a 95% decline in the region's vulture population.
从20世纪90年代，这种药物和其他威胁，从高压电线塔到栖息地的缩减，导致了这一区域秃鹫数量下降了95%。
In nearby Africa, poachers intentionally poison carcasses to prevent the birds' presence from alerting authorities to their location.
在邻近的非洲，偷猎者故意在尸体里投毒，来防止这些秃鹫的出现把他们所处的位置暴露给当局。
One poisoned carcass can kill over 500 vultures. Today, more than 50% of all vulture species are endangered.
一具有毒的尸体可以杀死超过500只秃鹫。当下，超过50%的秃鹫物种濒临灭绝。
In regions where vultures have gone extinct, corpses take three times longer to decay.
在秃鹫已经灭绝的区域，尸体要花三倍长的时间降解。
These carcasses contaminate drinking water, while feral dogs and rats carry the diseases into human communities.
这些尸体污染饮用水，然后野狗和老鼠把这些疾病带到居民区。
The Asian and African Vulture Crisis has led to an epidemic of rabies in India, where infections kill roughly 20,000 people each year.
亚洲和非洲的秃鹫危机已经造成了狂犬病在印度的流行，每年大约有2万人死于狂犬病。
Fortunately, some communities have already realized how important vultures are.
幸运的是，一些地方已经意识到了秃鹫的重要性。
Conservationists have successfully banned drugs like Diclofenac, while other researchers are working to repopulate vulture communities through breeding programs.
环保主义者已经成功地禁止了双氯芬酸等药物的使用，与此同时，另一些研究者在通过繁殖方案重新恢复秃鹫群落。
Some regions have even opened vulture restaurants where farmers safely dispose of drug-free livestock.
一些区域已经开设了供农民丢弃无毒牲口的秃鹫餐厅。
With help, vultures will be able to continue their role conserving the health of our planet -- transforming death and decay into life.
有了这些帮助，秃鹫将会继续它们扮演它们的角色，保护地球的健康--化死亡和腐烂为生机。