0:01:16 > 0:01:19Once upon a time, in the heart of Africa,
0:01:19 > 0:01:21there was a lake of fire.
0:01:26 > 0:01:29The lake's water burned with colour.
0:01:29 > 0:01:34Scarlet and crimson.
0:01:34 > 0:01:38And in its stillness held heaven's reflection.
0:01:57 > 0:02:03After months without rain, there came a season of drought.
0:02:03 > 0:02:08And the lake dried and turned white as ash.
0:02:18 > 0:02:23But in the desolation came the promise of another season.
0:02:23 > 0:02:26A season of colour and life.
0:02:26 > 0:02:29A season of beginning.
0:04:02 > 0:04:05Lake Natron in northern Tanzania
0:04:05 > 0:04:10lies at the very centre of East Africa's Great Rift Valley.
0:04:10 > 0:04:14This is a raw and unfinished land.
0:04:22 > 0:04:26Ol Doinyo Lengai rises from the lake's southern shore.
0:04:26 > 0:04:31A living volcano, restless and impatient.
0:04:41 > 0:04:43Hidden deep in its dark core,
0:04:43 > 0:04:48a chamber of magma burns with primeval energy.
0:04:54 > 0:04:56HISSING AND BUBBLING
0:05:22 > 0:05:28For the local Masai tribe, Lengai is simply where God lives.
0:05:36 > 0:05:39Natron is a vast, shallow lake,
0:05:39 > 0:05:4440 miles long and no more than six feet deep,
0:05:44 > 0:05:50and so toxic with soda salt that almost nothing can live in its water.
0:05:52 > 0:05:55But each year, for only a few weeks,
0:05:55 > 0:05:57rain comes to Natron.
0:05:59 > 0:06:03And a grand act of creation takes place -
0:06:03 > 0:06:07one of Africa's last great mysteries.
0:06:19 > 0:06:21FLAMINGOS HONK
0:06:27 > 0:06:31And with the rain come the flamingos.
0:06:41 > 0:06:46Somehow they know the time has come to return to Natron.
0:06:46 > 0:06:50They have abandoned a dozen other lakes along the Rift Valley
0:06:50 > 0:06:55and flown hundreds, even thousands, of miles to be here.
0:07:01 > 0:07:03ORCHESTRAL MUSIC
0:07:47 > 0:07:49ORCHESTRAL MUSIC
0:08:46 > 0:08:49THUNDER
0:08:55 > 0:08:58Each bird has its own story,
0:08:58 > 0:09:00its own secret life.
0:09:02 > 0:09:07And each story is one that began here at Natron with the rain.
0:09:20 > 0:09:24The rain triggers the growth of algae in the water.
0:09:24 > 0:09:28When the flamingos eat the algae, they transform.
0:09:28 > 0:09:33Their feathers, eyes and legs flush with crimson.
0:09:50 > 0:09:55It is their colour they find most attractive about each other.
0:09:55 > 0:10:00After all, this is why they have come to Natron -
0:10:00 > 0:10:02to find a mate.
0:10:04 > 0:10:06FLAMINGOS HONK
0:10:50 > 0:10:54Slowly, almost politely, they begin.
0:11:02 > 0:11:06Every movement part of a courtship,
0:11:06 > 0:11:08a choreography...
0:11:10 > 0:11:13a growing dervish of desire.
0:11:20 > 0:11:23PERCUSSION MUSIC
0:11:33 > 0:11:36WORLD MUSIC
0:12:25 > 0:12:27MUSIC SWELLS
0:12:49 > 0:12:52HEADS SWISH
0:13:13 > 0:13:15ORCHESTRAL MUSIC
0:14:08 > 0:14:10FLAMINGOS HONK
0:14:38 > 0:14:40MUSIC STOPS
0:14:45 > 0:14:48FLAMINGOS HONK
0:15:30 > 0:15:35One by one, the flamingos find each other.
0:15:35 > 0:15:38A pairing to last the season.
0:15:40 > 0:15:43A pairing that begins with a moment.
0:16:02 > 0:16:05There is a myth told by the Masai
0:16:05 > 0:16:09that the flamingos are made from the water's salt,
0:16:09 > 0:16:13that they are the children of the lake.
0:16:13 > 0:16:16But the truth is no less extraordinary,
0:16:16 > 0:16:20and something that only happens here at Natron.
0:16:25 > 0:16:29A secret island emerges from the middle of the lake.
0:16:35 > 0:16:40As the rainy season ends and the furnace sun resumes its rule,
0:16:40 > 0:16:46water evaporates so quickly that a residue of salt forms on the surface.
0:16:55 > 0:17:01Each day, the sun bears down and the salt thickens into sheets,
0:17:01 > 0:17:06like plates of salt ice that shift and grind in the wind.
0:18:07 > 0:18:13The sheets drift, blending into a series of small islands as they go.
0:18:14 > 0:18:18The wind pushes the islands towards the centre of the lake.
0:18:21 > 0:18:25After several weeks of intense evaporation,
0:18:25 > 0:18:30the water in the centre of the lake is only a few inches deep.
0:18:30 > 0:18:34The floating salt islands run aground on the emerging mud
0:18:34 > 0:18:41and soon accumulate into a single island of salt, ten miles wide.
0:18:43 > 0:18:47Here, remnant water congeals into sulphurous pools
0:18:47 > 0:18:52and the temperature regularly rises above 130 degrees.
0:18:57 > 0:19:02No land animal could travel or survive here.
0:19:02 > 0:19:08But to the flamingos, this strange, new world is a gift.
0:19:09 > 0:19:13There are 2 million lesser flamingos in East Africa.
0:19:13 > 0:19:18And every one of them is born here, on Natron's secret salt island.
0:19:25 > 0:19:27CROWD OF FLAMINGOS HONK
0:19:35 > 0:19:40The expectant parents build their nests from the salty lake mud.
0:19:43 > 0:19:46Even though the salt island is vast,
0:19:46 > 0:19:51as social birds, the flamingos prefer to group closely together,
0:19:51 > 0:19:55and define the boundaries of their chosen nest sites.
0:20:04 > 0:20:06The nests are almost a foot high,
0:20:06 > 0:20:12drier and a few degrees cooler than the floor of the salt island.
0:20:12 > 0:20:17The salt bakes, bleaches and hardens into a cradle.
0:20:28 > 0:20:32After the nest comes the egg.
0:20:34 > 0:20:39And then there is nothing to do but wait.
0:20:44 > 0:20:48For one long, hot month.
0:21:36 > 0:21:38SCRAPING AND CHIRPING
0:21:45 > 0:21:49Finally, a small but determined beginning.
0:21:53 > 0:21:55A new life -
0:21:55 > 0:21:57one that will start today,
0:21:57 > 0:22:02and might, if she's lucky, last for 40 years.
0:22:04 > 0:22:06A whole new story.
0:22:20 > 0:22:23PARENT HONKS AND BABY CHIRPS
0:22:31 > 0:22:35Her very first cries are unique.
0:22:35 > 0:22:38This is her own voice and how she and her parents
0:22:38 > 0:22:42will always be able to recognise each other.
0:23:06 > 0:23:11Within a few hours, her down dries in the hot sun
0:23:11 > 0:23:13and she tries to stand...
0:23:28 > 0:23:32something that will take only a little more practice.
0:24:01 > 0:24:03Then it's time for food,
0:24:03 > 0:24:07a high-energy liquid made from the lake's algae,
0:24:07 > 0:24:11but also containing traces of her parents' own blood.
0:24:39 > 0:24:41For these first days,
0:24:41 > 0:24:46she has the constant presence of one or other of her parents.
0:24:46 > 0:24:49This is a time of bonding and intimacy.
0:25:07 > 0:25:10The dark hollow under her mother's wing
0:25:10 > 0:25:14is a favourite place to hide from the fierce sun.
0:25:39 > 0:25:41FLAMINGOS ALL SQUAWK
0:25:51 > 0:25:55While still small, the chicks stay in the parents' shadows
0:25:55 > 0:25:57or on their nest mounds,
0:25:57 > 0:26:00anything to stay cool.
0:26:34 > 0:26:36BABY SQUEAKS
0:27:24 > 0:27:28At about a week old, her legs are strong enough
0:27:28 > 0:27:34and, with a little encouragement, she decides to leave the nest.
0:28:06 > 0:28:11Her world expands, one unsteady step at a time.
0:28:18 > 0:28:22Now that she can walk, her relationship with her parents
0:28:22 > 0:28:26will become more and more about separation.
0:28:33 > 0:28:38Like every other chick, her inclination is to be with others -
0:28:38 > 0:28:43the comfort and familiarity of her kind,
0:28:43 > 0:28:48for a life that is not so much about the individual, but a collective.
0:29:04 > 0:29:06Up to half a million adults and chicks
0:29:06 > 0:29:10live in this season's noisy and boisterous nursery.
0:29:10 > 0:29:13FLAMINGOS SQUAWK
0:29:53 > 0:29:58But the island can also be harsh and unkind,
0:29:58 > 0:30:02an impermanent place of salt and extreme heat.
0:30:07 > 0:30:10When the chicks walk through the puddles of thick, salty water
0:30:10 > 0:30:12that are all around,
0:30:12 > 0:30:17a thin band of salt sometimes forms on their ankles.
0:30:21 > 0:30:24If it does or not seems a matter of luck.
0:30:24 > 0:30:27But the more these chicks wade into the water,
0:30:27 > 0:30:29the more the salt accumulates
0:30:29 > 0:30:34and hardens into a cement shackle that cannot be broken.
0:30:56 > 0:31:00High above the colonies, the marabou storks appear,
0:31:00 > 0:31:03circling like storybook witches.
0:31:06 > 0:31:09They have come from far beyond the lake
0:31:09 > 0:31:14with their own mysterious knowledge of what happens at Natron.
0:31:17 > 0:31:18Very quickly...
0:31:21 > 0:31:24..their intentions become clear.
0:31:25 > 0:31:27SINISTER MUSIC
0:31:33 > 0:31:35ALL CHIRP
0:32:33 > 0:32:35ALL CHIRP
0:32:50 > 0:32:56Almost insatiable, a few marabous can kill hundreds of chicks,
0:32:56 > 0:32:59scattering and scaring off the parents.
0:33:38 > 0:33:40STORK HONKS
0:34:20 > 0:34:23With their gentle curved beaks,
0:34:23 > 0:34:27the flamingos are no match for the marabous.
0:34:30 > 0:34:35But every once in a while, a parent wins a reprieve for her chick.
0:34:58 > 0:35:01One day, the chicks have had enough.
0:35:04 > 0:35:08Perhaps some instinct tells them of a better place,
0:35:08 > 0:35:11somewhere beyond the salt.
0:35:24 > 0:35:28Suddenly, in their hundreds of thousands,
0:35:28 > 0:35:30they abandon their nursery.
0:35:32 > 0:35:34ORCHESTRAL MUSIC
0:36:34 > 0:36:39Guardian birds lead them away and out across the miles of the salt island,
0:36:39 > 0:36:43perhaps on routes they took themselves when they were chicks.
0:37:24 > 0:37:27But there are those who are left behind,
0:37:27 > 0:37:30too weak or too injured to make the journey.
0:37:40 > 0:37:42Stories that barely began.
0:38:41 > 0:38:46Each day, the surviving chicks continue on across the burning miles.
0:39:01 > 0:39:06Though they are reunited each evening with their parents for rest and food,
0:39:06 > 0:39:11it is the guardian birds who lead this daytime march
0:39:11 > 0:39:14and make sure even the smallest find their way.
0:39:32 > 0:39:35But the group can't wait for everyone.
0:40:07 > 0:40:10The chicks burdened with salt shackles
0:40:10 > 0:40:13fall further and further behind.
0:40:35 > 0:40:38SQUEALS
0:41:08 > 0:41:14But, for the hundreds of chicks who die, thousands will make it.
0:41:33 > 0:41:35How far they've come.
0:41:42 > 0:41:45The groups merge and gather momentum,
0:41:45 > 0:41:50as if, at last, they sense the destination.
0:42:01 > 0:42:05And, reaching the edge of the salt island, find the lake
0:42:05 > 0:42:09with its cool, blue water.
0:42:20 > 0:42:23And she has made it, too.
0:42:48 > 0:42:50Cautiously at first.
0:42:51 > 0:42:53But then...
0:43:33 > 0:43:36Up ahead...
0:43:36 > 0:43:38..there are the others.
0:44:25 > 0:44:30Leaving the salt island, the chicks enter the wider kingdom of the lake.
0:44:35 > 0:44:39Here, a very different world awaits them.
0:44:41 > 0:44:45A living landscape, complex and animate.
0:44:47 > 0:44:49MONKEYS SQUAWK
0:45:25 > 0:45:27BIRDS CHIRRUP
0:45:51 > 0:45:55The rift's escarpment rises 1,000ft above the lake,
0:45:55 > 0:45:58a rock wall severed by deep canyons.
0:46:01 > 0:46:04Here, amid the shadows and the swifts,
0:46:04 > 0:46:08water gushes up from hundreds of underground springs.
0:46:08 > 0:46:11The water is rich in sodium carbonate,
0:46:11 > 0:46:15the mineral that creates the salty chemistry of the lake.
0:47:18 > 0:47:22Dozens of springs and rivers feed into a series of marshes
0:47:22 > 0:47:24that border the lake.
0:47:24 > 0:47:26Almost all of Natron's life
0:47:26 > 0:47:31depends upon the relatively fresh water of this abundant green maze.
0:47:31 > 0:47:37And, for the next few months, so too will the chicks.
0:48:35 > 0:48:38Each morning, the parents leave their chicks
0:48:38 > 0:48:40on the muddy shore below the marsh.
0:48:42 > 0:48:46They spend the day almost completely unsupervised.
0:49:21 > 0:49:23They learn to feed themselves.
0:49:23 > 0:49:27Their beaks are developing the filters and distinctive shape
0:49:27 > 0:49:30that will allow them to separate the algae they need
0:49:30 > 0:49:33from the mud and silt of the marsh.
0:49:44 > 0:49:49Her super-soft down is the perfect insulation against the strong sun.
0:49:49 > 0:49:52But it requires frequent grooming,
0:49:52 > 0:49:54not only to keep it healthy,
0:49:54 > 0:49:57but to encourage the growth of adult feathers.
0:50:18 > 0:50:23Without those feathers, she can't fly -
0:50:23 > 0:50:26no matter how hard she tries.
0:50:39 > 0:50:43There are plenty of things to want to fly away from.
0:50:49 > 0:50:53The mongoose that lives in the marsh, for instance.
0:51:36 > 0:51:41As the chicks change and grow, life in the marsh goes on.
0:51:43 > 0:51:46Routine, yet quietly full of wonder.
0:52:31 > 0:52:33BIRDS CHIRP
0:52:59 > 0:53:03At three months old, she has grown more sure of herself,
0:53:03 > 0:53:05and her place in the marsh.
0:53:19 > 0:53:24Now her down has transformed into a juvenile plumage.
0:53:25 > 0:53:27And one by one...
0:53:27 > 0:53:31..her wing feathers have fledged.
0:54:01 > 0:54:05The day comes when she discovers her wings are strong enough.
0:54:08 > 0:54:13And a whole new way of being is suddenly possible.
0:54:13 > 0:54:18A flight that at first stays close to the lake and marsh,
0:54:18 > 0:54:21the familiar places of her life.
0:54:21 > 0:54:25But a flight that will soon release her,
0:54:25 > 0:54:29above the Earth, above everything she has known.
0:55:12 > 0:55:14No longer a chick,
0:55:14 > 0:55:20but a young bird whose wings have given her the whole Rift Valley.
0:55:38 > 0:55:41Every 30 years, Lengai erupts.
0:55:45 > 0:55:48Deep in the volcano's molten core,
0:55:48 > 0:55:55lava is pulverised by pressure into ash and thrown upward into the air.
0:55:59 > 0:56:02The ash contains sodium carbonate,
0:56:02 > 0:56:06the exact mineral in the lake's water and soil.
0:56:06 > 0:56:12It is as if each aspect of the lake's landscape is simply a different form,
0:56:12 > 0:56:18a different incarnation of the same basic element.
0:56:18 > 0:56:21Natron is one place.
0:56:21 > 0:56:25Water, earth and air.
0:56:49 > 0:56:54And the flamingos, born on the lake's salt island,
0:56:54 > 0:56:57transformed by its salt water,
0:56:57 > 0:57:00embody Natron in a living form.
0:58:11 > 0:58:14The flamingos' ceaseless journeys
0:58:14 > 0:58:16among the many lakes of the Rift Valley
0:58:16 > 0:58:19are nomadic rather than migratory.
0:58:19 > 0:58:23For the flamingos move of their own accord.
0:58:29 > 0:58:33Natron, Bogoria, Empakai,
0:58:33 > 0:58:36Magadi, Nakuru, Manyara.
0:58:36 > 0:58:39They come and go as they want,
0:58:39 > 0:58:44their presence the sudden and complete possession of a lake.
0:59:39 > 0:59:43But every lake has its storybook witches.
1:00:39 > 1:00:41DRAMATIC MUSIC
1:01:20 > 1:01:23MUSIC STOPS
1:01:59 > 1:02:02This time, she keeps her story.
1:02:02 > 1:02:05She keeps her secret life.
1:02:13 > 1:02:17Just as they arrived at Natron, like a magic act,
1:02:17 > 1:02:21the flamingos suddenly disappear.
1:03:10 > 1:03:13Born of salt, they possess the sky.
1:03:13 > 1:03:15They absorb the colour of the water
1:03:15 > 1:03:20and their feathers burnish crimson as the Phoenix.
1:03:21 > 1:03:25Their lives are continual transformation.
1:03:25 > 1:03:30And even in death, their forms shift to something other.
1:03:31 > 1:03:34Their feathers, bones, colour,
1:03:34 > 1:03:37their life force, return to the lake.
1:04:05 > 1:04:10As the seasons change, microscopic life in the water blooms.
1:04:10 > 1:04:13Natron becomes a lake of fire.
1:04:43 > 1:04:47After six months without a single drop of rain,
1:04:47 > 1:04:50the colour fades and bleaches.
1:05:17 > 1:05:20The ash of the volcano blends with the salt of the lake
1:05:20 > 1:05:22and the dust of the Earth,
1:05:22 > 1:05:27scattering in the restless dry-season wind.
1:05:32 > 1:05:37Natron's elements shapeshift, one into the other.
1:05:37 > 1:05:41Ash, dust and salt.
1:06:05 > 1:06:08But even this season of silence will pass.
1:06:21 > 1:06:25The story of the bird is a promise to us -
1:06:25 > 1:06:28Nature's affirmation.
1:06:40 > 1:06:43In winter or in death,
1:06:43 > 1:06:50in times of desolation, the rain will arrive.
1:06:50 > 1:06:53The call of the birds will be heard.
1:06:53 > 1:06:58And everything, everything, can begin again.
1:06:58 > 1:07:01THUNDER AND TORRENTIAL RAIN
1:07:36 > 1:07:41Lightning Bird, Firebird, Phoenix.
1:07:41 > 1:07:47She will return on crimson wings and make a nest among the ashes.
1:07:53 > 1:07:57And the children of the lake will be reborn.
1:08:08 > 1:08:10SCRAPING
1:08:43 > 1:08:45CHIRPS
1:10:33 > 1:10:40Once upon a time, in the heart of Africa, there was a lake of fire.
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