Tonight on NOVA. High above the arid desert of East Africa lies a towering mountain chain with a bizarre climate. It's hard to believe anything could live here, winter nights and summer days. But these endangered animals live only here, marooned on a mountain island in a sea of clouds. Africa, as you haven't seen it before. A journey to Kilimanjaro. Funding for NOVA's 20th anniversary season is made possible by Lockheed, America's aerospace company, supporting math, science and engineering education for national technology leadership. And Johnson & Johnson, the signature recognized around the world for commitment to quality health care products for the entire family. Major funding for NOVA is provided by the Corporation for Public Broadcasting and by annual financial support from viewers like you. In tropical Africa, there's a world on the equator so bleak it resembles the Arctic. It's a hidden world of harsh extremes of smoking summits and bitter cold. Here, life is tested to the limit. This is a story of nature's extraordinary power to survive on even these remote mountain realms, beyond the African clouds. The Great Plains of East Africa, a golden land supporting the most familiar gathering of wildlife under the sun. Here, the animals move through grasslands as boundless as the oceans. But above the furnace heat of the plains, towers another land, created by volcanism over 30 million years, a process that formed Africa's Great Rift Valley. Where it crosses East Africa are four giant mountains. In Tanzania, Kilimanjaro and Oldonyo Lengai. In Kenya, Mount Kenya and the Abadayas. Thrust violently from the Earth's core, they tower over the landscape. These mountains are like islands, their wildlife marooned above a sea of cloud. Mount Kenya, rising over three miles into the African sky. This is an ancient volcano, three million years old. Time has quenched its fires. Like oceanic islands, each East African mountain has its own special community of animals and plants. Highland rock hyraxes are unique to Mount Kenya. After a night of sub-zero temperatures, these creatures need a full two hours of sunbathing before they're warm enough to move freely. They are much larger and have thicker coats than hyraxes on the hot plains below. In the thin mountain air, their improved insulation helps them cope with both the bitter cold and the fearsome rays of the equatorial sun. A blanket of downy leaves protects the giant ostrich plume Lobelia. Buried within are tiny flowers, sought out by sunbirds. In return for pollination, the plants provide sugary nectar. Because of its intimate partnership with this astonishing plant, the scarlet-tufted malachite is the only sunbird that can live at this great height. Keeping warm at high altitude is critical. Small antelope with coats fluffed like highland sheep prosper on alpine herbs. These are grey dikers. By mid-morning, the mountain is warming up. The hyrax colony is active, with mothers tending their young. Grazing mostly around their burrows, hyraxes are also fond of the giant grouncil's fleshy leaves. These plants may take a century to grow to this size, only to be stripped within hours. But reaching them isn't easy. For the short-legged hyrax, the long-stemmed grouncil is quite a challenge. When moisture-laden air from the Indian Ocean rises over the peaks, it brings a dramatic change to the landscape. The sun is obscured, temperatures plummet. Suddenly the equator is gripped by arctic conditions. And Makinda's eagle owl sits tight. It's hard to believe that on the savannas below, the land is baking hot. Yet here, three miles high, there's a blizzard. The storm creates a land more like Alaska than Africa. Despite these freezing conditions, tropical birds like streaky seed-eaters continue to breed. When the first European explorers claimed they had seen snow on Africa's equator, their accounts were met with utter disbelief. But even they were unlikely to have witnessed this, the heaviest snowfall in half a century. And it won't last, the power of the tropical sun sees to that. Hot water pours off the mountain, crystal-clear, and so pure that little grows in its wake. But a strange and primitive plant manages to eke a living in upland lakes. Like fairy rings, this algae grows in circles, drawing on what meagre nourishment there is. It shows that life can colonise even the harshest of places. Mount Kenya is not eternal, sun, wind and snow rip at its volcanic carcass. In another three million years, this mountain will be a much lesser monument. In the sky there will be the One day, Mount Kenya may even look like this. The Abadayas, an ancient volcanic island 40 miles west. The Abadayas are twice as old as Mount Kenya. They have frost-shattered peaks worn down to lava stumps, known as the dragon's teeth. Herds of elephants, wanderers from below, are hardy enough to invade these elevated moorlands. Four thousand feet lower than Mount Kenya, the Abadaya range has a milder climate. Without strong competition, plants like heather grow into giants, 20 feet tall. To their huge appetites, elephants seem to relish these oversized shrubs. Other mammals also take to the mountain life. On the African savannas, lions seem to suffer in the stifling heat. But up here, these big tropical cats thrive in the cool climate. A chance encounter at 12,000 feet between Africa's top predator and mightiest mammal ends in a standoff. Being large, warm-blooded and highly mobile, lions and elephants can travel up and down mountains with ease. But at altitude, the thin air carries less oxygen. Forest animals like buffalo may find the Abadayas a struggle, but they could never scale the breathless heights of distant Mount Kenya. Heather and tussock grass blanket much of the moors. Fed by upland streams, this is a paradise for all kinds of animals, some as small as the striped mouse. Its ancestors once lived on the hot plains, today it's a successful mountaineer. Luckily for the mice, it's too cold for most snakes on this chilly moorland. But another enemy is seldom far away, a serval cat, the ultimate mouser. Long legs allow it to peer over the grasses, and those outsize ears are fine-tuned to pick up the slightest rustle. Male servals are loners, consorting only occasionally with females to mate. They spend much of the day patrolling their home range and hunting. The hair in the ears works as a filter, sifting the sounds of wind in the grass from the faint movements of prey. But up here, there is an even more spectacular cat. This, too, is a serval, a black variety. Black servals occur elsewhere, but on these mountains they are more abundant than usual. Why this should be so remains a mystery. Although servals mainly hunt rodents and small birds, an unwary diker is also potential gain. A pair of black servals may produce spotted young. A spotted pair may even have black offspring. On the abadaires, both versions of this beautiful cat are common. All mountains crumble with age. Today, the abadare range is a shadow of its former self, yet enough rain falls on its rounded tail. Living around these torrents are slender-billed chestnut-winged starlings. Their lives are linked with water, perilously so. As the water tumbles down the mountain, it becomes warmer and gathers nutrients sufficient to support insect food for the starlings. The birds live in small groups, keeping contact through calls that penetrate the sound of rushing water. Within the flock, pairs mate for life. During the breeding season, they're inseparable. But like any couple, they have their differences as they gather nest material for their home by the falls. Like a tide from the world beneath, cool mist rises in the morning air. The abundant moisture supports lush cloud forest. Here, at cloud level, the mountain receives its highest rainfall. Forest rivers attract elephants to drink. The herd is led by a matria, a veteran blessed with the wisdom of years, who probably learnt the whereabouts of this place from her mother. The tangled forest favours opportunists like lions. Here, they're as much in evidence as on the high moorlands. For some reason, lion numbers in the Aberdeers have risen sharply in recent years. The abundance of lions may be responsible for the decline of East Africa's largest, rarest and certainly most elusive forest antelope, the bongo. Fewer than 50 remain in East Africa. The Aberdeers are their last refuge. East African bongos were separated from others in Central Africa when lowland forests receded. Now they are castaways, marooned on this mountain island. This male lives by himself except when joining a herd of females in search of a mating. His grimace is a response to the scent of a female in season. Some already have young, a glimmer of hope for this magnificent antelope. Notoriously shy and secretive, the bongo must use all its powers of concealment if it's not to disappear forever from the mountain forests of East Africa. The Aberdeer forest hides many other surprises. Tucked away in a glade, a pair of diker feed on shoots and mosses. Nothing exceptional in that, but their keen sense of smell leads them to a bizarre encounter. This is a crested rat. To the diker it literally stinks. The Kenyan highlands are one of the few places these rare creatures can be found. The rat's skunk-like appearance advertises a noxious odour. When threatened, it exposes a poison gland along the sides of its body. With this deterrent openly on show, it wanders boldly through the undergrowth. Because the mountains generate abundant moisture, bamboo thrives here. Along the lower margins of the bamboo belt, dense forest and dazzling flowers flourish. This leonotis offers nectar to a passing sunbird. In the cool mountain climate, where there are fewer insects, many plants use warm-blooded birds for pollination. But at lower, warmer altitudes, insects share the task. In this world of the miniature, there are the hunters and the hunted. Jackson's chameleon, resembling a pocket dinosaur with an insatiable appetite. Its hunting skill is made possible by one of the most amazing designs in the natural world. Fired like a sniper's bullet, it seldom misses, the fastest tongue in Africa. On these isolated mountains, the process of evolution has created some peculiar species. Jackson's chameleon, with its unique head of horns, is one of them. Being a cold-blooded reptile, it is found only in the lower reaches of the forest. Males patrol and defend favored hunting branches from other males. When trespass leads to conflict, size is all important. A male chameleon's horns are his weapons. Females also have horns, but theirs are much smaller. To threaten each other, males strum their horns. The vibrations are detected by others nearby. When opponents of equal size meet, battle is bound to follow. The aim is to toss your opponent out of the tree. The outcome is settled, and the loser moves on. Chameleons are ancient reptiles, older even than the mountains themselves. The world around them is changing while they remain the same. Although feeding in lush cloud forest, rousers like buffalo cannot get all the minerals they need. In particular, their food lacks salt, so they're forced to visit salt licks, special places where minerals have been exposed by erosion. Here, countless tongues and hooves have laid bare the soil, and in doing so are slowly wearing the mountain away. The salt lick is important to all kinds of animals, customers who, on a normal day, wouldn't meet. A young bull elephant clears the lick for the rest of the herd. His family, treading carefully, are regulars here. A quick taste confirms this is a good place to excavate the soil for salt. Some elephants prefer to use their left tusk, others their right. Whichever one they favor most is sometimes called the slave tusk. The trunk is the elephant's most versatile tool. It works as a nose and a hand all roll into one. Growing up presents all sorts of problems. For a weak old calf on a long expedition to the salt lick, it's been a tiring day. A salt lick, opened up by elephants, is eagerly visited by others like giant forest hogs, the largest wild pigs in the world. These pigs are confined to the mountain forests of Africa. Shy and nocturnal, they rarely leave the safety of the forest during the day. Also, Sykes monkeys come here, sporting the distinctive white bibs found only in the Aberdeers and Mount Kenya. It's mid-afternoon, time to enjoy the other reason for the visit. The baby, too young to mud wallow, must stay out of trouble until it's over. Day by day, the Aberdeers and Mount Kenya are slowly being ground to dust. With the passage of time, these mountains will eventually die. Their remains will be scattered across the hot African plains. Today, the same cataclysmic forces that built Mount Kenya and the Aberdeers are still at work. Bursting from the plains come new islands in the African sky. Towering 9,000 feet and a mountain in the making, Aldonyo Lengai, the Maasai, mountain of God. Recently, this young volcano erupted, covering all life on its slopes with a suffocating blanket of ash. But already, nature's advance guard is returning. These Clipspringers are skilled mountaineers with nimble tiptoed hooves for scaling rocks. In the cool of the evening, they find warmth on the lava itself. But the antelope may be pushing their luck. Another mighty eruption is long overdue. Aldonyo Lengai, at half the height of Mount Kenya, is a young island, barely piercing the clouds and still growing. But there is a mountain in Africa, mightier than them all, a colossus which dwarfs Lengai, whose summit soars almost four miles into the sky. Kilimanjaro, the White Mountain. In a tropical forest which may freeze by night, mouse birds and monkeys alike must huddle for warmth. For a family of Sykes monkeys, morning sunshine brings relief from the cold. This forest, nurtured by a wreath of clouds, rises straight from the parched plains below. The moisture supports creatures like this Kilimanjaro chameleon. It's different from those found on other mountains. Broad-ringed white eyes, unique to this mountain and neighbouring islands, are quick to find a forest pool. Kilimanjaro's volcanic rock is porous, so surface water is short-lived. The Choga people of Kilimanjaro have a legend that a great flood once swept their mountain. The good was spared, but all the wicked people were turned into elephants. Yet these powerful spirits of the forest inspire anything but evil. Every big East African mountain encourages the evolution of its own brand of wildlife. On Kilimanjaro, Sykes monkeys lack white bibs. They're all grey, unknown as gentle monkeys. As well as mountain specialists, other more widespread creatures settle here, like the heart-loub's Turaco. Birds and large mammals make good mountain pioneers because they're able to travel to new places with ease. Colobus monkeys are common to most Central African cloud forests, but their black and white pattern differs slightly from mountain to mountain. The leading male's unearthly roars herald the gathering dust. Towards evening, as the forest settles, the temperature plunges. Moonrise over the summit is a signal for the night shift to emerge. The genet, a fleet-footed hunter. Despite its cat-like appearance, it belongs to the mongoose family. The genet occurs widely in Africa, in woodlands and grasslands. Here on Kilimanjaro, it has reached the upper limit of its range. Genets hunt mainly by sound, listening for stirrings of birds and small mammals. This mouse, feeding on a fallen fig, seems unaware of its presence. But the mouse, too, has sharp ears. In its boathole, it can do little but hide and wait. Beyond the tree line is an alien, unforgiving world, locked in an icy silence. Nothing moves except the soil, heaving as ice crystals push to the surface. Here it is winter every night, and summer every day. Few large mammals can make a living at 13,000 feet, but Elan managed to survive in the shadow of Kilimanjaro's glaciers. Young lobelias unfurl to greet the rising sun. The alpine warland is steadily released from a night spent in the freezer. In places, the churning of the soil prevents plants from rooting. Where the night crystals bloom, only the hardiest grasses survive. So great is its height that living on Kilimanjaro is harsher than anywhere else in Africa. Here the lobelias are tougher even than those on Mount Kenya, triumphing over the elements. Protected by leaves filled with antifreeze, the tiny flowers produce abundant nectar for sunbirds. But it's the giant groundsals on Kilimanjaro that reach record heights, growing up to 30 feet tall. Fine leaf hairs protect their crowns from nightly frosts and intense solar radiation by day. Their swollen stems are lagged with dead foliage to reduce moisture loss in the dry air. Out in the heather on the alpine moorland, mountain chats have made their home. For healthy growth, the nestlings need a mixed diet of insects and sugar. The adults comb the giant lobelias for nectar, instant energy for hungry youngsters. At 14,000 feet, Kilimanjaro becomes more like an island than ever, and there's still almost a mile to go. Updrafts from its icy flanks launch sky hunters on their endless search for carrion. These are lamegeirs, mountain vultures, Africa's largest birds of prey. White-necked ravens are first to a buffalo carcass, a recent victim of the cold. Gliding on wings nine feet across, this young lamegeir can cover immense distances in a short time, an asset on a mountain nearly 40 miles long. Ravens and vultures are born scavengers, but lamegeirs are interested only in bones and marrow fat. The bird's appetite is formidable. It can swallow bones a foot long. This one, bigger than your fist, is bite-size. The name lamegeir refers to lamb catching. Since this is only a myth, the bird is also known as the bearded vulture. With a gulp and a stretch, the bone is eased on its way to the stomach to be dissolved in digestive juices as strong as an acid bath. Bearded vultures mature after seven years, when their full adult plumage gives them an altogether more majestic appearance. Pickings are slim on Kilimanjaro's upper slopes. Food is so sparse that this vast mountain can support only one family of these rare vultures. In the whole of East Africa, there may be no more than 50 pairs. Above the alpine moorland, volcanic forces have built a land beyond the reach of life, Africa's high arctic. The ground is barren, the cold unbearable. Even the air fills with a stardust of ice crystals. Bearing a crown of ice, Kilimanjaro's majestic summit towers far above the clouds. The White Mountain. A silent world empties the moon. Four miles up. On the roof of Africa are permanent glaciers embedded in ash. It is hard to imagine that the equator is only three degrees to the north, the scorching plains a few miles below. In time Kilimanjaro may rise higher still, for at its heart the crater still breathes. For now the slumbering giant bides its time. Kilimanjaro, the undisputed monarch of all mountain islands in the African sky. In time Kilimanjaro may rise higher still, for at its heart the crater still breathes. In time Kilimanjaro may rise higher still, for at its heart the crater still breathes. A production of WGBH Boston. Funding for NOVA is provided by Johnson & Johnson, the signature recognized around the world for commitment to quality health care products for the entire family. And Lockheed, America's aerospace company, supporting math, science and engineering education for national technology leadership. Major funding for NOVA is provided by the Corporation for Public Broadcasting and by annual financial support from viewers like you. Teachers, educational institutions and organizations can purchase this and many other programs from NOVA's 20th anniversary season for $19.95 plus shipping and handling. To order a videocassette call 1-800-255-9424. This is PBS. Next time on NOVA. 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