0:00:08 > 0:00:11The Ethiopian highlands.
0:00:11 > 0:00:14The roof of Africa.
0:00:19 > 0:00:2130 million years ago,
0:00:21 > 0:00:26this was a vast high-altitude plateau the size of Spain.
0:00:31 > 0:00:34Since then, the elements have carved the landscape
0:00:34 > 0:00:37into Africa's equivalent of the Grand Canyon.
0:00:54 > 0:00:56Millions of years of erosion
0:00:56 > 0:00:59have created isolated islands of alpine terrain
0:00:59 > 0:01:04supporting strange and unique creatures found nowhere else on earth.
0:01:04 > 0:01:07MONKEYS CHIRP
0:01:20 > 0:01:24The gelada baboon needs a head for heights,
0:01:24 > 0:01:28where a single slip would mean certain death.
0:01:35 > 0:01:38Geladas are exclusive to this chilly plateau,
0:01:38 > 0:01:41kept warm by a long fur coat.
0:01:42 > 0:01:46They are the highest-dwelling primates on the planet,
0:01:46 > 0:01:49ranging up to 4,500 metres.
0:01:50 > 0:01:53BABOON GRUNTS
0:01:53 > 0:01:57But what's really surprising is their sheer numbers.
0:01:57 > 0:02:01Geladas are the most sociable monkeys on earth.
0:02:03 > 0:02:07Like the game herds of the Serengeti, they are vegetarians.
0:02:09 > 0:02:14In these high pastures, they take the place of grazing antelopes.
0:02:24 > 0:02:29But geladas aren't the only peculiar creatures up here on the roof of Africa.
0:02:33 > 0:02:35This is a giant mole rat...
0:02:35 > 0:02:37SQUEAKS
0:02:37 > 0:02:41..a specialised grass-eater that's unique to the Ethiopian highlands.
0:02:42 > 0:02:45The mole rat lives underground,
0:02:45 > 0:02:49emerging at dawn and dusk to snatch mouthfuls of grass,
0:02:49 > 0:02:53which it drags back to its burrow to munch at leisure.
0:02:53 > 0:02:54MOLE RAT SQUEAKS
0:02:57 > 0:02:59There's every reason to be cautious.
0:02:59 > 0:03:02This foxy-looking Ethiopian wolf
0:03:02 > 0:03:07preys almost exclusively on giant mole rats.
0:03:45 > 0:03:47MOLE RAT SQUEAKS, WOLF GROWLS
0:04:00 > 0:04:05Despite the wolf's best efforts, mole rats are incredibly common.
0:04:05 > 0:04:09It's estimated there may be more than 15,000 of them
0:04:09 > 0:04:12in each square mile of grassland.
0:04:12 > 0:04:18Yet despite their high numbers, mole rats and geladas never meet.
0:04:18 > 0:04:21So, how can that be?
0:04:23 > 0:04:25The answer is this.
0:04:25 > 0:04:30Dividing geladas on one side from mole rats on the other,
0:04:30 > 0:04:33the Great Rift Valley runs through Ethiopia,
0:04:33 > 0:04:35slicing the roof of Africa in two.
0:04:39 > 0:04:40But it doesn't stop there.
0:04:42 > 0:04:45Extending 3,000 miles further south,
0:04:45 > 0:04:50the Great Rift shapes and defines the entire landscape of East Africa,
0:04:50 > 0:04:54creating intense hot spots of evolution.
0:05:06 > 0:05:11All along the Rift Valley, soaring above the hot, dusty plains,
0:05:11 > 0:05:16isolated mountain peaks harbour unique wildlife communities.
0:05:18 > 0:05:21A kaleidoscope of strange and remarkable creatures.
0:05:33 > 0:05:35As well as extraordinary wildlife,
0:05:35 > 0:05:39there's something else that's special about these mountains.
0:05:42 > 0:05:44They all share a common origin
0:05:44 > 0:05:48that is key to understanding how the rift was formed...
0:05:51 > 0:05:56..and why it has had such a far-reaching impact on this part of Africa.
0:06:01 > 0:06:03The first clue lies here,
0:06:03 > 0:06:07at the very northern margin of the Great Rift Valley.
0:06:11 > 0:06:14Ethiopia's Danakil Depression.
0:06:31 > 0:06:34This is Erta Ale,
0:06:34 > 0:06:36Africa's most active volcano.
0:06:38 > 0:06:41It contains the world's only permanent lava lake.
0:06:51 > 0:06:54Like a window into the fiery heart of the earth,
0:06:54 > 0:07:00Erta Ale provides a terrifying glimpse of the inner workings of our planet.
0:07:02 > 0:07:05A cauldron of molten rock beneath our feet.
0:07:19 > 0:07:25In geological terms, Erta Ale's volcano is still in its infancy.
0:07:25 > 0:07:28But 1,000 miles to the south,
0:07:28 > 0:07:33another Rift Valley volcano has been growing for at least a million years.
0:07:35 > 0:07:37Rising to the east of the Great Rift Valley,
0:07:37 > 0:07:42snow-capped Kilimanjaro towers nearly four miles high.
0:07:42 > 0:07:44It's Africa's loftiest peak
0:07:44 > 0:07:48and the tallest free-standing volcano on earth.
0:07:50 > 0:07:56Kilimanjaro and Erta Ale are just two links in a long chain of volcanoes
0:07:56 > 0:07:58that runs the length of the Great Rift.
0:08:01 > 0:08:05In fact, all the mountains along the rift are volcanic,
0:08:05 > 0:08:08born deep beneath the earth's surface.
0:08:12 > 0:08:16Scientists believe that a plume of superhot lava
0:08:16 > 0:08:19has been rising up beneath the crust of East Africa
0:08:19 > 0:08:20for millions of years.
0:08:24 > 0:08:29The thick crust above the plume has been lifted more than a mile high,
0:08:29 > 0:08:32causing cracks to appear around its margins.
0:08:36 > 0:08:40The Eastern and Western Rift Valleys mark the fractured edges
0:08:40 > 0:08:42of the uplifted East African Plateau,
0:08:42 > 0:08:45with further branches extending outwards.
0:08:47 > 0:08:50And wherever molten rock has seeped through from below,
0:08:50 > 0:08:52huge volcanoes have grown up.
0:08:55 > 0:08:58It's estimated that over the last 30 million years,
0:08:58 > 0:09:02the rift's volcanoes have poured out enough molten rock
0:09:02 > 0:09:07to bury an area the size of Wales to a depth of 15 miles.
0:09:45 > 0:09:50Mount Kenya's 5,200-metre-high summit is an eroded lava plug,
0:09:50 > 0:09:53suggesting it was once even taller.
0:10:24 > 0:10:26Below the summit,
0:10:26 > 0:10:30a belt of strange and unique alpine plants clings to the slopes.
0:10:34 > 0:10:38Even on the equator, mountain weather is unpredictable.
0:10:46 > 0:10:48Just a few miles away,
0:10:48 > 0:10:53lions and zebra are sweltering under a blazing African sun,
0:10:53 > 0:10:57yet here, on Mount Kenya, a sudden squall can bring snow,
0:10:57 > 0:11:00creating a winter wonderland.
0:11:09 > 0:11:12This extreme climate poses a real challenge
0:11:12 > 0:11:15to the mountain's wild inhabitants.
0:11:18 > 0:11:22Highland rock hyraxes are found only on Mount Kenya.
0:11:28 > 0:11:32High mountain hyraxes have evolved to cope with the cold.
0:11:32 > 0:11:36They are much larger than lowland hyraxes
0:11:36 > 0:11:38and have exceptionally dense fur,
0:11:38 > 0:11:41which allows them to maintain their core temperature
0:11:41 > 0:11:43in freezing mountain conditions.
0:11:43 > 0:11:45HYRAXES CALL
0:11:51 > 0:11:55When the sun reappears, the hyraxes save energy by sunbathing.
0:12:23 > 0:12:27Giant alpine plants insulate their delicate buds from frost damage
0:12:27 > 0:12:31by wrapping them in a protective duvet of leaves,
0:12:31 > 0:12:36which unfurl one by one as the temperature rises.
0:12:42 > 0:12:47The giant ostrich plume lobelia has evolved a peculiar life cycle.
0:12:49 > 0:12:53After several years of growth, it sprouts a huge flower spike,
0:12:53 > 0:12:59containing hundreds of tiny flowers swathed in a mass of furry insulation.
0:13:01 > 0:13:05Up here, over two and a half miles above sea level,
0:13:05 > 0:13:07insect pollinators are scarce,
0:13:07 > 0:13:11so the lobelia has developed an alternative partnership.
0:13:11 > 0:13:13BIRD CHIRPS
0:13:17 > 0:13:22The plant attracts high-flying sunbirds with a rich supply of nectar.
0:13:33 > 0:13:37The sunbirds use the lobelia as a fuelling depot,
0:13:37 > 0:13:40a social meeting point
0:13:40 > 0:13:42and a sunbathing perch.
0:13:46 > 0:13:52In return, the lobelias get pollinated and set seed.
0:13:54 > 0:13:58Further down the mountain, at around 3,000 metres,
0:13:58 > 0:14:02lives perhaps Mount Kenya's strangest resident -
0:14:02 > 0:14:04the side-striped chameleon.
0:14:13 > 0:14:17This cold-blooded reptile is uniquely adapted for mountain life,
0:14:17 > 0:14:20far above the altitude where reptiles normally survive.
0:14:22 > 0:14:25As dawn breaks, it creeps onto an exposed perch,
0:14:25 > 0:14:29where it lines up its body at right angles to the rising sun.
0:14:34 > 0:14:37Then, flushing its skin with dark pigment,
0:14:37 > 0:14:40it soaks up the rays like a solar panel.
0:14:43 > 0:14:47It takes only minutes to raise its temperature 30 degrees Celsius.
0:14:49 > 0:14:53Once warmed, it changes to normal daytime colour.
0:14:57 > 0:15:00The male chameleon is fiercely territorial.
0:15:02 > 0:15:05If another male has the nerve to set foot on his bush,
0:15:05 > 0:15:08there's bound to be a fight.
0:15:13 > 0:15:14CHAMELEONS HISS
0:15:34 > 0:15:37A sneaky bite clinches the bout...
0:15:39 > 0:15:42..and the loser slinks off to nurse his bruises.
0:15:47 > 0:15:48Further up the mountain,
0:15:48 > 0:15:52the hyraxes have also completed their morning sunbathe.
0:15:52 > 0:15:54HYRAXES SQUEAK
0:15:58 > 0:16:00Though it looks like a short-eared rabbit,
0:16:00 > 0:16:03the hyrax has some peculiar features
0:16:03 > 0:16:06which suggest a much stranger kinship.
0:16:08 > 0:16:12The layout of its toes is practically identical to those of an elephant.
0:16:14 > 0:16:18Its teeth and bones are also similar, though scaled down a little.
0:16:24 > 0:16:26The life of a baby hyrax looks cosy.
0:16:27 > 0:16:34But sunbathing out in the open makes them a tempting target for predators.
0:16:40 > 0:16:42HYRAX SQUEAKS
0:16:44 > 0:16:46An augur buzzard.
0:16:54 > 0:16:56BUZZARD CRIES
0:16:56 > 0:16:59SQUEAKS
0:17:21 > 0:17:2440 miles west of Mount Kenya,
0:17:24 > 0:17:27the Aberdares Mountains are the legacy of an older volcano
0:17:27 > 0:17:33that's been severely eroded, but still towers over 2½ miles high.
0:17:41 > 0:17:46In the frosty alpine grassland, a rare predator is on the prowl.
0:17:48 > 0:17:51At lower altitudes, servals have a spotted coat,
0:17:51 > 0:17:55but up here, many of them are black.
0:17:58 > 0:18:00Some scientists believe
0:18:00 > 0:18:05that a dark coat may help the cats to absorb heat on cold, bright days.
0:18:17 > 0:18:23In the cool mountain conditions, giant heathers form a dense carpet -
0:18:23 > 0:18:26food for Africa's highest-resident elephants...
0:18:30 > 0:18:34..including one of the biggest tuskers in the world.
0:18:40 > 0:18:45Unlike most herbivores, elephants can process almost any plant they find,
0:18:45 > 0:18:47including tough heather bushes.
0:18:47 > 0:18:50ELEPHANTS GROWL
0:18:55 > 0:19:00A century ago, elephants migrated freely between the Aberdares and Mount Kenya.
0:19:00 > 0:19:04But as the human population has increased locally,
0:19:04 > 0:19:09the herd has become marooned in its upland enclave with nowhere to go.
0:19:12 > 0:19:14In these mountain forests,
0:19:14 > 0:19:18one of Africa's rarest antelopes, the mountain bongo,
0:19:18 > 0:19:20is making a last stand.
0:19:24 > 0:19:27Bongos are extremely shy and secretive,
0:19:27 > 0:19:31staying in dense, shady forest during daylight hours.
0:19:40 > 0:19:45Human pressures have now reduced their numbers to around 100
0:19:45 > 0:19:47within the Aberdares National Park.
0:19:50 > 0:19:54And these have been bred for release into the wild.
0:20:00 > 0:20:04The Aberdares lie along the eastern escarpment of the Kenyan Rift Valley,
0:20:04 > 0:20:08which here is up to 100 miles across.
0:20:08 > 0:20:13Right in the centre of this landscape sits a remarkable volcano,
0:20:13 > 0:20:16virtually untouched by the outside world.
0:20:19 > 0:20:21SHEEP BLEAT
0:20:27 > 0:20:30Mount Suswa is home to Masai pastoralists,
0:20:30 > 0:20:33who graze their herds on the flat crater floor.
0:20:37 > 0:20:40But Suswa is no ordinary volcano.
0:20:42 > 0:20:46At its centre, steep cliffs plunge 500 metres
0:20:46 > 0:20:49into a ring-shaped Rift Valley in miniature.
0:21:07 > 0:21:11Around 100 families from the Red Trees Masai community
0:21:11 > 0:21:13share the resources of Suswa's grassy crater.
0:21:19 > 0:21:24Cattle are at the centre of Masai life - the measure of a family's wealth.
0:21:31 > 0:21:34With a six-month dry season
0:21:34 > 0:21:38and no permanent streams or lakes anywhere inside the crater,
0:21:38 > 0:21:42keeping a supply of drinking water is a constant challenge.
0:21:47 > 0:21:51But the Masai have found an ingenious solution to the problem.
0:21:53 > 0:21:58A system of metal pipes condenses steam from volcanic vents.
0:21:58 > 0:22:00ANIMATED CHATTER, LAUGHTER
0:22:40 > 0:22:42At the centre of the crater,
0:22:42 > 0:22:44Mount Suswa's unique circular moat
0:22:44 > 0:22:48encloses a lava plateau two miles across -
0:22:48 > 0:22:53a miniature lost world protected by a ring of cliffs.
0:22:55 > 0:22:58It's thought that Suswa's volcano last erupted
0:22:58 > 0:23:00just a couple of hundred years ago,
0:23:00 > 0:23:05and parts of the 'lost world' are still smouldering.
0:23:14 > 0:23:18The Masai consider this wild, tangled jungle a sacred place,
0:23:18 > 0:23:21where no hunting or grazing is allowed.
0:23:51 > 0:23:53When Suswa's volcano last erupted...
0:23:56 > 0:23:59..this moat was a cauldron of molten rock.
0:24:04 > 0:24:08The liquid lava has since cooled and solidified,
0:24:08 > 0:24:14but along the moat's rim, the volcano still hides a dark secret.
0:24:19 > 0:24:21This sunlit boulder pile was formed
0:24:21 > 0:24:25when the rock collapsed above an underground cavern,
0:24:25 > 0:24:30opening a window into the volcano's main artery,
0:24:30 > 0:24:36where molten lava once flowed unseen beneath the skin of the mountain.
0:24:48 > 0:24:52Once the volcano stopped erupting and the lava drained away,
0:24:52 > 0:24:56it left behind a vast network of empty passages,
0:24:56 > 0:24:59some big enough to drive a bus through.
0:25:02 > 0:25:06Cave explorers have mapped over six miles of massive tunnels
0:25:06 > 0:25:08beneath this single lava flow.
0:25:09 > 0:25:14But humans weren't the first creatures to discover this hidden world.
0:25:18 > 0:25:22As dusk creeps up the flanks of Mount Suswa,
0:25:22 > 0:25:25a troop of baboons is gathering for the night.
0:25:25 > 0:25:27BABOONS CHATTER
0:25:32 > 0:25:34Most baboons roost in the treetops
0:25:34 > 0:25:37to avoid night-prowling leopards or lions.
0:25:42 > 0:25:45But these baboons are heading downwards.
0:26:12 > 0:26:14Their destination is an underground chamber
0:26:14 > 0:26:18known locally as the 'baboons' parliament'.
0:26:27 > 0:26:29As they enter the underworld,
0:26:29 > 0:26:32the baboons cross with bats on their way out.
0:26:35 > 0:26:38Filming them here requires an infra-red camera
0:26:38 > 0:26:41and lights invisible to the baboons.
0:26:46 > 0:26:50The walls of the baboon parliament have been worn glassy-smooth
0:26:50 > 0:26:54by the hands and feet of generations of baboons.
0:26:57 > 0:27:00Rockclimbing in the dark on polished holds
0:27:00 > 0:27:03could be considered a hazardous sport,
0:27:03 > 0:27:07but presumably, these baboons find it less scary
0:27:07 > 0:27:10than sleeping outside with the leopards.
0:27:18 > 0:27:20The baboons' final destination
0:27:20 > 0:27:24is a series of small ledges high up on the cave wall.
0:27:28 > 0:27:33Safe beyond the reach of predators and protected by a roof of solid rock,
0:27:33 > 0:27:36the cave dormitory stays warm and dry,
0:27:36 > 0:27:40even at the height of the rainy season.
0:27:45 > 0:27:51As the last light fades from the sky, the bat exodus intensifies.
0:27:51 > 0:27:56This is the world's largest colony of giant mastiff bats.
0:27:56 > 0:28:00It's made up entirely of females who have just given birth.
0:28:02 > 0:28:07Their pups - thousands of them - can't fly yet
0:28:07 > 0:28:10and are completely dependent on their mothers.
0:28:14 > 0:28:17But the mother bats must leave their cave to feed.
0:28:20 > 0:28:22Packed tightly together for warmth,
0:28:22 > 0:28:26the deserted pups are left in a wriggling, squeaking creche.
0:28:37 > 0:28:39In all this confusion,
0:28:39 > 0:28:43a baby bat has lost its grip and fallen to the cave floor.
0:28:46 > 0:28:52The tunnel is alive with creepy creatures of all kinds.
0:28:52 > 0:28:57Many are partial to the flesh of a baby bat.
0:29:24 > 0:29:29As dawn breaks over the volcano, the baboons leave their sleeping-cave.
0:29:48 > 0:29:52After a hard night's insect-catching in the skies above the Rift Valley,
0:29:52 > 0:29:55the bats return home to roost.
0:29:56 > 0:30:01Somehow, in the chaos of fluttering adults
0:30:01 > 0:30:03and thousands of squeaking babies,
0:30:03 > 0:30:07each mum must track down her own infant to give it its morning feed.
0:30:11 > 0:30:13She does this
0:30:13 > 0:30:16firstly by remembering where she parked her baby the night before,
0:30:16 > 0:30:22then, as she gets closer, by recognising its voice and unique scent.
0:30:29 > 0:30:33Like all mammals, baby bats depend on their mothers' milk.
0:30:36 > 0:30:40Her little wriggling pup is frantic for its morning feed.
0:30:59 > 0:31:03While bats and baboons seek sanctuary
0:31:03 > 0:31:06in the protective environment of Mount Suswa's lava caves,
0:31:06 > 0:31:09a very different kind of creature
0:31:09 > 0:31:14has chosen what must be the Rift Valley's most exposed habitat.
0:31:23 > 0:31:28The sheer 500-metre-high cliffs of Mount Ololokwe
0:31:28 > 0:31:32are constantly buffeted by strong winds rising from the valley below.
0:31:51 > 0:31:53This precarious location
0:31:53 > 0:31:57is home to Kenya's largest nesting colony
0:31:57 > 0:32:00of Ruppell's griffon vultures.
0:32:14 > 0:32:16Vultures thrive in the rift
0:32:16 > 0:32:19because the steep valley walls create updraughts,
0:32:19 > 0:32:21which they can use to get airborne.
0:32:28 > 0:32:31Gliding effortlessly from one thermal to the next,
0:32:31 > 0:32:34a vulture can cover 200 miles in a day,
0:32:34 > 0:32:39soaring seven miles high with scarcely a wing flap.
0:32:47 > 0:32:50From their lofty lookout above the African plains,
0:32:50 > 0:32:53nothing escapes their notice.
0:33:00 > 0:33:04Out in the Serengeti grassland, the game herds are on the move.
0:33:05 > 0:33:10This is what the vultures have been waiting for.
0:33:21 > 0:33:23GROWLS
0:33:39 > 0:33:41ZEBRA BARKS
0:33:49 > 0:33:51ZEBRA YELPS
0:34:23 > 0:34:25Vultures have a clear pecking order.
0:34:25 > 0:34:27SCREECHES
0:34:27 > 0:34:32The heavy-billed lappet-faced vultures are best equipped to open up a carcass,
0:34:32 > 0:34:34so they get the greatest respect.
0:34:35 > 0:34:40Once they're finished, the white-backed and griffon vultures pile in
0:34:40 > 0:34:42and squabble over the spoils.
0:34:43 > 0:34:45WILDEBEEST LOW
0:34:51 > 0:34:55The Serengeti is home to the world's greatest game herds.
0:34:55 > 0:34:58Most of it lies on the East African Plateau,
0:34:58 > 0:35:01perched around a mile above sea level,
0:35:01 > 0:35:06the result of uplift by the same lava plume that created the Rift Valley.
0:35:08 > 0:35:11But it has another, even more intimate connection
0:35:11 > 0:35:13with the rift's fiery origins.
0:35:15 > 0:35:20The Serengeti borders Tanzania's most active volcano -
0:35:20 > 0:35:22Ol Doinyo Lengai.
0:35:27 > 0:35:29In 2007,
0:35:29 > 0:35:35Ol Doinyo Lengai produced a spectacular eruption that lasted almost a year...
0:35:38 > 0:35:40..throwing out thousands of tons of ash...
0:35:43 > 0:35:46..which fell on the surrounding savanna.
0:35:50 > 0:35:51As volcanic ash breaks down,
0:35:51 > 0:35:54it creates a dense, fertile soil
0:35:54 > 0:35:57which is hard for tree roots to penetrate
0:35:57 > 0:36:00but is perfect for grass.
0:36:02 > 0:36:07The great grass plains of the Serengeti can support over a million wildebeest
0:36:07 > 0:36:11only because of the fertility of the vast volcanic ash deposits
0:36:11 > 0:36:13on which they grow.
0:36:15 > 0:36:18South of the Serengeti, in southern Tanzania,
0:36:18 > 0:36:22the Rift Valley's eastern and western branches converge.
0:36:22 > 0:36:28Close to their meeting point lies one of the Great Rift's best-kept secrets -
0:36:28 > 0:36:32the alpine grassland of the Kitulo Plateau,
0:36:32 > 0:36:35known locally as 'God's Garden'.
0:36:38 > 0:36:40It provides the stage
0:36:40 > 0:36:44for one of Africa's most spectacular floral displays.
0:37:17 > 0:37:22The Kitulo meadows are serviced by some unusual insect pollinators.
0:37:23 > 0:37:28This is a monkey beetle, a hairy-coated living fossil.
0:37:32 > 0:37:35During the ice ages, when Africa was much cooler,
0:37:35 > 0:37:37monkey beetles were widespread,
0:37:37 > 0:37:43but now they survive only in a few high-altitude meadow lands.
0:37:46 > 0:37:48CHIRPS
0:37:49 > 0:37:52The spectacular-plumed mountain marsh widowbird
0:37:52 > 0:37:54is another local specialty.
0:38:12 > 0:38:14On the slopes of the Kitulo Plateau,
0:38:14 > 0:38:20a line of protea sugar bushes marks the transition between meadow and forest.
0:38:21 > 0:38:25Their blooms produce a feast of pollen and nectar,
0:38:25 > 0:38:29but for the monkey beetles, it's a dangerous prize.
0:38:38 > 0:38:42Once in place, the Tempel's chameleon,
0:38:42 > 0:38:45an insect hunter peculiar to this corner of Tanzania,
0:38:45 > 0:38:48hardly needs to move.
0:38:56 > 0:38:59Chameleons are unique among reptiles
0:38:59 > 0:39:03in having the ability to swivel their eyes independently.
0:39:03 > 0:39:05When they line them up,
0:39:05 > 0:39:08the stereo image allows them to launch their sticky tongue
0:39:08 > 0:39:12exactly the right distance to nail their victim
0:39:12 > 0:39:13every time.
0:39:23 > 0:39:28Below the line of sugar bushes, where the chameleons stalk their prey,
0:39:28 > 0:39:33a belt of dense jungle clings to rain-drenched mountain slopes.
0:39:33 > 0:39:35INSECTS CHIRP
0:39:38 > 0:39:42The cool, humid climate fosters ancient tree ferns
0:39:42 > 0:39:44and towering hardwood trees.
0:39:56 > 0:39:58Isolated from other mountain forests
0:39:58 > 0:40:01by the converging arms of the Great Rift Valley,
0:40:01 > 0:40:05Mount Rungwe's forests are home to unique creatures.
0:40:12 > 0:40:16The area has recently become the focus for scientific research
0:40:16 > 0:40:19and new species are being discovered all the time...
0:40:21 > 0:40:23..even up in the treetops.
0:40:32 > 0:40:34This is a kipunji,
0:40:34 > 0:40:39first discovered in 2005 and never filmed before.
0:40:50 > 0:40:54In looks and behaviour, the new monkey resembles a mangabey.
0:40:56 > 0:40:59But its DNA is similar to a baboon's.
0:41:08 > 0:41:13For now, the evolutionary origins of the charismatic kipunji
0:41:13 > 0:41:15remain shrouded in mystery.
0:41:31 > 0:41:35Kipunjis are particularly fond of this sticky orange cucumber fruit,
0:41:35 > 0:41:38which sprouts from vines in the treetops.
0:41:43 > 0:41:46They're known to feed on over 100 different plants
0:41:46 > 0:41:49and play a crucial role in dispersing their seeds.
0:41:55 > 0:41:59But even while scientists begin to uncover their secret lives,
0:41:59 > 0:42:03kipunjis are teetering on the verge of extinction.
0:42:03 > 0:42:05KIPUNJIS CALL
0:42:06 > 0:42:08LAUGHTER, CONVERSATION
0:42:10 > 0:42:13As the isolated forests around Mount Rungwe
0:42:13 > 0:42:16are cleared for farming and firewood...
0:42:17 > 0:42:20..the kipunjis' unique forest habitat is shrinking.
0:42:23 > 0:42:28With a mere 1,000 individuals remaining in the wild,
0:42:28 > 0:42:30they are already the rarest monkeys in Africa.
0:42:30 > 0:42:34There may be little time left to study them.
0:42:57 > 0:43:01Fortunately, kipunjis do have friends,
0:43:01 > 0:43:06and a project is now under way to safeguard a part of their forest home
0:43:06 > 0:43:08and involve local people in their protection.
0:43:24 > 0:43:26North-west of the kipunjis' mountain home,
0:43:26 > 0:43:31a branch of the Great Rift curves between Tanzania and the Congo.
0:43:33 > 0:43:37The valley floor contains vast deepwater lakes,
0:43:37 > 0:43:41while to the west lies a series of volcanic mountains
0:43:41 > 0:43:43up to three miles high.
0:43:43 > 0:43:47And the most spectacular are here,
0:43:47 > 0:43:49in the Virungas National Park.
0:44:08 > 0:44:15The Virungas volcanoes are home to Africa's largest and rarest great ape...
0:44:18 > 0:44:19GORILLA GRUNTS
0:44:19 > 0:44:21..the mountain gorilla.
0:44:24 > 0:44:27Mountain gorillas evolved from lowland gorillas,
0:44:27 > 0:44:30which colonised the Virungas less than half a million years ago,
0:44:30 > 0:44:33soon after these volcanoes formed.
0:44:38 > 0:44:41They responded to the challenge of high-altitude living
0:44:41 > 0:44:45by becoming larger and furrier than their lowland cousins,
0:44:45 > 0:44:50enabling them to cope with the permanently cold, miserable weather.
0:44:51 > 0:44:57A combination of fertile volcanic soil and two metres of annual rainfall
0:44:57 > 0:45:01encourages a profusion of plants on the mountain slopes...
0:45:03 > 0:45:06..ideal fodder for giant vegetarian apes.
0:45:18 > 0:45:21In response to their fibrous diet,
0:45:21 > 0:45:24the gorillas have developed extra-large chewing teeth
0:45:24 > 0:45:27and extra-powerful jaw muscles
0:45:27 > 0:45:30anchored to a prominent ridge of bone on the crown of their head.
0:45:47 > 0:45:50Gorilla society is well ordered,
0:45:50 > 0:45:53with each band of females and their young
0:45:53 > 0:45:55protected by a huge silver-backed male.
0:45:55 > 0:45:57GORILLA GRUNTS
0:46:00 > 0:46:05With few natural enemies prepared to brave the wrath of a silverback,
0:46:05 > 0:46:08young gorillas can play to their hearts' content.
0:46:14 > 0:46:16The unique characteristics
0:46:16 > 0:46:19that separate mountain gorillas from their lowland cousins
0:46:19 > 0:46:22evolved as a result of their isolation
0:46:22 > 0:46:26on just a handful of volcanoes along the Great Rift.
0:46:28 > 0:46:31It makes them vulnerable, especially to poaching -
0:46:31 > 0:46:35though, fortunately, they have many human allies
0:46:35 > 0:46:37fighting to ensure their survival.
0:46:42 > 0:46:45Mountain gorillas are, without doubt,
0:46:45 > 0:46:48one of the Great Rift's most remarkable creatures,
0:46:48 > 0:46:54their evolution uniquely shaped by the volcanic terrain in which they live.
0:46:56 > 0:47:02That terrain has itself been moulded and shaped by the fiery rocks beneath,
0:47:02 > 0:47:06creating a complex of valleys and volcanoes
0:47:06 > 0:47:08spanning the length of East Africa.
0:47:17 > 0:47:19For those animals and plants
0:47:19 > 0:47:23which were able to adapt to the changing conditions,
0:47:23 > 0:47:27the Great Rift has promoted a remarkable burst of evolution.
0:47:31 > 0:47:34In this turbulent landscape,
0:47:34 > 0:47:37volcanic fire has proved to be less a destroyer,
0:47:37 > 0:47:40but more a creator of new life.
0:47:46 > 0:47:51And that is what is so special about Africa's Great Rift.
0:48:05 > 0:48:08One of the Great Rift team's most difficult assignments
0:48:08 > 0:48:12took them deep into Mount Suswa's volcanic crater,
0:48:12 > 0:48:15home to a troop of very unusual baboons.
0:48:18 > 0:48:23Instead of spending the night in trees, they have taken to sleeping down caves.
0:48:29 > 0:48:32Cameraman Justin Maguire is here to film them.
0:48:35 > 0:48:40Masai elder Jeremiah ole Tanin will be Justin's guide.
0:48:40 > 0:48:44He hopes that the baboons will attract visitors to Mount Suswa,
0:48:44 > 0:48:47generating income for his community.
0:48:48 > 0:48:50JUSTIN: Wow. That's pretty impressive.
0:48:50 > 0:48:52- Yeah.- Fantastic cave.
0:48:52 > 0:48:55So, this is where the baboons come and sleep, is it?
0:48:55 > 0:48:58Yeah. It is where they spend during the night.
0:48:58 > 0:49:00'With the baboons out foraging for the day,
0:49:00 > 0:49:03'Justin has a chance to recce the cave.
0:49:03 > 0:49:07'Jeremiah warns that when they return at dusk,
0:49:07 > 0:49:10'they will be wary and easily spooked,
0:49:10 > 0:49:12'and baboons can be dangerous.
0:49:12 > 0:49:14'Justin will have to be on guard.'
0:49:14 > 0:49:18- So, how many baboons use this cave? - Over 100.
0:49:18 > 0:49:21100 baboons? That's incredible. And I'm going to be in there with them?
0:49:21 > 0:49:24- So it's going to make 101 baboons?- Oh, yeah. - JEREMIAH LAUGHS
0:49:24 > 0:49:27- You think they'll be frightened of me?- Yeah, yeah.
0:49:27 > 0:49:32I'm hoping I can be a bit like a baboon and they'll be relaxed with me.
0:49:32 > 0:49:36'Justin's problem is that if he tries to climb down here at night,
0:49:36 > 0:49:41'he'll wake any baboons sleeping close to the entrance.
0:49:41 > 0:49:44'Luckily, Jeremiah has a cunning plan.'
0:49:44 > 0:49:47MASAI MEN SING, WHOOP
0:49:52 > 0:49:54The Masai know of a concealed entrance
0:49:54 > 0:49:58which should give Justin the chance to sneak in unseen.
0:49:58 > 0:50:01MEN SING IN MASAI
0:50:04 > 0:50:07Before venturing down at night,
0:50:07 > 0:50:10he decides to go for a daylight run-through.
0:50:10 > 0:50:13- That is one bendy ladder.- Yeah.
0:50:17 > 0:50:20OK. Here goes. Freak!
0:50:21 > 0:50:26To film in such a tricky situation, Justin has an experienced team with him.'
0:50:26 > 0:50:28OK. I'm sending your bag down, OK?
0:50:31 > 0:50:37Phil Chapman is the director, but he is also an experienced caver.
0:50:39 > 0:50:41Once inside, it becomes apparent
0:50:41 > 0:50:44that getting both them and the equipment through the cave
0:50:44 > 0:50:48is not going to be as easy as they first thought.
0:50:48 > 0:50:51- It looks tiny, Jeremiah.- Yeah.
0:50:51 > 0:50:53- Can we really get through there? - Yeah, yeah.
0:50:53 > 0:50:56I can hear bats. Are there bats in there?
0:50:57 > 0:51:00I do like these things.
0:51:01 > 0:51:02OK.
0:51:07 > 0:51:10That's quite good. That's fine for them to crawl through.
0:51:10 > 0:51:13- Oh, watch your head. - Very sharp stalactites.
0:51:14 > 0:51:20'Inside, the team find thousands of bats preparing for a night's hunting.
0:51:20 > 0:51:23'Not only do the bats produce tons of droppings,
0:51:23 > 0:51:27'they also share the cave with less welcome inhabitants.'
0:51:27 > 0:51:31Oooh, look. Look at these millions of fleas.
0:51:31 > 0:51:33No, they are. I can feel them crawling up my trouser leg.
0:51:33 > 0:51:35That is quite amazing.
0:51:35 > 0:51:37I'm absolutely covered in fleas. Look at my leg.
0:51:45 > 0:51:49'Finally, they reach the baboons' sleeping chamber,
0:51:49 > 0:51:51'and Jeremiah was right.
0:51:51 > 0:51:54'The signs of baboons are everywhere.'
0:51:54 > 0:51:58As you can just see, all the rocks are smooth.
0:51:58 > 0:52:00Very smooth. Shiny.
0:52:00 > 0:52:03- Just feel it. - Yeah, that's incredibly smooth.
0:52:03 > 0:52:05- Very smooth and shiny.- Yeah.
0:52:05 > 0:52:09It's just because of rubbing of their bottom...the baboons...
0:52:09 > 0:52:12Right. So, these have got...
0:52:12 > 0:52:13They're smooth because of...
0:52:13 > 0:52:16the baboons' bottoms have rubbed on these for many years?
0:52:16 > 0:52:19- Yeah, yeah. They've been rubbed... - I can see baboon poo on the top.
0:52:19 > 0:52:21- Oh, yeah. See?- OK.
0:52:23 > 0:52:27'Knowing that baboons are here in numbers is great news for filming,
0:52:27 > 0:52:29'but poses Justin with another problem.
0:52:29 > 0:52:34'Baboons could be extremely dangerous in the confined space of the cave,
0:52:34 > 0:52:39'so Justin needs some way to scare them off if they come too close.'
0:52:39 > 0:52:45The BBC, in their thoughtfulness, have provided me with a rape alarm,
0:52:45 > 0:52:49in case I have trouble with any of the baboons.
0:52:49 > 0:52:52There are some big males, aren't there?
0:52:52 > 0:52:54- Oh, yeah.- I'm hoping I'm not going to have to...
0:52:54 > 0:52:56ALARM SOUNDS
0:52:56 > 0:52:57ALARM STOPS Ah.
0:52:57 > 0:53:00ALL LAUGH
0:53:00 > 0:53:03I'm hoping I'm not going to get to the stage they're attacking me.
0:53:03 > 0:53:04Oh, yes.
0:53:04 > 0:53:08'Not only will the team have to build a hide,
0:53:08 > 0:53:11'they also have to rig up special lights producing infra-red,
0:53:11 > 0:53:13'which the baboons can't see.
0:53:13 > 0:53:19'But it's close to sunset, and the baboons are already on their way.'
0:53:19 > 0:53:22We don't have enough time. That's the big problem.
0:53:22 > 0:53:25No, seriously, we're very close to not being able to light this.
0:53:25 > 0:53:27We're going to have to start now.
0:53:29 > 0:53:32If the baboons return early and find the team,
0:53:32 > 0:53:36they may desert the cave, scuppering any chance of filming.
0:53:38 > 0:53:42It's 5.50, and the sun will be setting pretty soon.
0:53:42 > 0:53:46We've run out of time and we don't want to be here whilst the baboons return.
0:53:46 > 0:53:50- Phil, I think you guys should really go.- OK.
0:53:50 > 0:53:52- Plug that one in. - I'll plug that one in, yeah.
0:53:54 > 0:53:57'With the lights rigged,
0:53:57 > 0:54:01'the team leave to allow the baboons to settle in for the night.'
0:54:12 > 0:54:15We've just got down into the cave now. Um, it's night.
0:54:15 > 0:54:18It's one thing walking through the cave with all the guys,
0:54:18 > 0:54:24another walking through it at night with 60 baboons,
0:54:24 > 0:54:27which I am a little bit nervous about.
0:54:28 > 0:54:30JUSTIN GRUNTS
0:54:30 > 0:54:33'Justin is in total darkness,
0:54:33 > 0:54:36'filming himself in infra-red light,
0:54:36 > 0:54:39'which neither he nor the baboons can see.'
0:54:39 > 0:54:40BATS CHIRP
0:54:45 > 0:54:47(I've found my guide string now,
0:54:47 > 0:54:51(which leads me to the last bit of the hide.)
0:54:57 > 0:54:59PEBBLE FALLS
0:54:59 > 0:55:01BABOON BARKS
0:55:05 > 0:55:07(I think a baboon's seen me.)
0:55:10 > 0:55:12BABOON BARKS
0:55:19 > 0:55:21BABOON BARKS
0:55:21 > 0:55:24BARKS CONTINUE
0:55:30 > 0:55:32Right. I've made it into my hide.
0:55:32 > 0:55:35And, uh...I've definitely been spotted by one baboon.
0:55:40 > 0:55:42BARKS
0:55:52 > 0:55:56I think the baboon that spotted me has fallen asleep, so, hopefully...
0:55:56 > 0:55:58BABOON BARKS No.
0:55:58 > 0:56:00He's still barking.
0:56:09 > 0:56:14Incredibly quiet. I'm really amazed how quietly they sleep.
0:56:23 > 0:56:27The only thing that's changing is the bat sounds.
0:56:27 > 0:56:28There's more and more bats in the cave,
0:56:28 > 0:56:31which is a clear signal that dawn is approaching,
0:56:31 > 0:56:33and soon the baboons are going to wake up, I think.
0:56:51 > 0:56:53BABOON SCREECHES
0:56:55 > 0:57:00It seems like a defining sound of the morning are the babies squealing.
0:57:00 > 0:57:03It sounds like any... any household, really.
0:57:04 > 0:57:06BABOON SQUEALS
0:57:09 > 0:57:13'Justin's perseverance has revealed for the first time
0:57:13 > 0:57:16'the underground behaviour of these unique baboons.
0:57:21 > 0:57:26'And back at camp, he can share these glimpses with the team.'
0:57:26 > 0:57:30I have never seen a baboon sleeping.
0:57:30 > 0:57:32ALL LAUGH
0:57:35 > 0:57:39'In the past, baboons were persecuted for killing livestock.
0:57:39 > 0:57:42'However, attitudes are slowly changing.'
0:57:42 > 0:57:45They will not be killing them.
0:57:45 > 0:57:48We want now to start to conserve them,
0:57:48 > 0:57:53to...to get a relationship between baboons and human beings,
0:57:53 > 0:57:58because their community can benefit from them.
0:57:59 > 0:58:02'Justin's filming quest has been a success,
0:58:02 > 0:58:05'and as interest in Mount Suswa increases,
0:58:05 > 0:58:08'the Masai will be able to share with others
0:58:08 > 0:58:10'their unique cave-dwelling baboons.'
0:58:19 > 0:58:22Subtitles by Red Bee Media Ltd