A sea of salt sucked dry by the Kalahari sun
These are the thirsty lands of Makgadikgadi in Botswana
Once long ago, this was one of the greatest lakes in Africa
Today, it's just a ghost lake
tormented by dust devils and shunned by all living things
Yet, every so often, may be only once in every 10 years
these harsh soda flats which cover some 4000 square miles are transformed
And at night, an unearthly music falls from the sky
bringing the lost lake back to life
In these years of sudden floods
flamingos from thousands of miles away fly in to breed
In weeks to come, some of their chicks will set out on another journey
on which they will not fly but walk
There is a mystery here
nobody knows how flamingos time their arrival to meet the flood at this desolate place
or even where they come from
But some instinct guides them through the night
By daybreak, they are arriving in their tens of thousands
The migration includes both Lesser and Greater flamingos
Lesser flamingos have darker bills and brighter feathers than their larger paler cousins
Hungry after their long journey, both species feed and could live together
Although the soda pans are flooded for thousands of square miles, the edges are shallow,
allowing the birds to sift the saline waters for algae and brine shrimps brought to life by the rains
Within days of arrival, the greater flamingos head for this island
far from the shore in the south of the pan
Here they will breed after a strict formal courtship
signaling their intentions with turning heads and flashing wings
Now begins a race against time
They must pair off, nest and raise their young before the waters dry up
They quarrel over nesting sites
After the female has laid her single egg,
the male takes turns with her to sit on the nest
There is no shade and every day is hotter than the last
The shoreline has already begun to recede as the first chicks appear
Not all the chicks emerge at once
while the first to hatch are busy getting into their stride
some adults are still seeking a mate
The result is a multitude of chicks of very different sizes
The last birds to breed find their nest surrounded by throngs of jostling youngsters
These chicks hungrily search for pieces of eggshell
The shells, rich in calcium are an essential addition to their diet
Lost in the forest of legs,
this tiny chick must be protected by its parent if it is to avoid being trampled
Despite the clamor, each chick can recognize its parents' call
This means the adults can fly off to feed knowing instinctively that when they return,
the chicks will respond to their calls only
and they will be able to find them in the crowd
In the late afternoon, parties of adults begin to stream home
from their feeding grounds in the deeper waters to the north
Excitement builds among the chicks as feeding time approaches
For some, the waiting is over
one by one, each chick is reunited with its parent
Adults continue to fly in through the night to feed their hungry chicks
The young too are at their most active in the hours after dark
Food becomes energy to be used for learning the precarious art of walking on stilts
The first hatched chicks are still being fed, but they are almost ready to fledge
Soon they'll be able to join the dawn flights to the feeding grounds
There the newly fledged chicks feed for themselves and become independent
Meanwhile on the island the remaining chicks are becoming increasingly restless
They begin bunching together to form large groups - cr¨¨ches
A number of different species of birds do this
It's a way of protecting themselves, the safety in numbers
Unlike other African breeding areas the Makgadikgadi pans have virtually no resident predators
but the chicks' urge to form cr¨¨ches is still strong
A large number of chicks from the overcrowded colony form a distinct group
and prepare to leave the densely packed island
Excitement rises as the group gets bigger
Older flamingos encourage the momentum
The tiny birds prepare to make a journey of several miles to a new home
By dividing into smaller groups like these,
the colony has greatly increased its chance of survival
As if at a given signal they stream away
The youngest chicks are surrounded by older birds,
they will soon fledge and join the others in the north
Here the water is deeper, and still fresh enough to hold fish and support pelicans
But while the greater flamingos find sanctuary in the north
the lesser flamingos in the south have only now started to breed
The water here is rapidly evaporating in the searing heat
only a thin blue skin remains
Islands of soda crust emerge like blisters as the lakebed is exposed
Far out on the dry lakebed, hidden from the shoreline by the heat haze
more than 100,000 lesser flamingos are starting to breed
Each pair builds a huge nest of mud and soda
These raised mounds protect the eggs from the windblown water
and keep them above the pan's scorching surface
Magnificent in their full breeding plumage
and with feathers fluffed out in territorial display
the birds shift from one leg to another
shaking off the clinging soda sludge before settling down
At noon, the heat of the sun is almost beyond endurance
but the parents incubate their egg for 30 days
Those birds that are released from incubation duty, fly off to feed
It's the only time in the year that they travel in daylight
Flamingos normally fly over dry land at night
and by now this part of the pan is more land than water
Returning birds find noticeable changings as the remaining water rapidly disappears
By now, these first chicks have hatched and are now forming cr¨¨ches
They're still far from being able to look after themselves and time is running out
Conditions change rapidly now
The last of the water is almost gone
and the colony is marooned in a cloying sea of mud
Small groups of adults remain as guides
They fly low over the chicks encouraging them
They must be ready for the ordeal to come
Ahead lies the cruelest of migrations,
a 50-mile forced march across one of the most inhospitable places on earth
The pan is now an oven
Its bed baked to a soda crust in the blinding heat
where recently blue water stretched to the horizon,
there remain only these strange telltale signatures imprinted in the soda
that show where the flamingos have been feeding
Some 15 miles out, a tiny pool has briefly fortified the living island of 40,000 chicks
From now on, there will be no more water
until they reach their destination, still several weeks away
Horizons melt in the furnace heat
Hot winds race across the pan sending clouds of stinging salt crystals thousands of feet into the sky
For the chicks, there is no turning back
Marching north into the void, they must cross the Makgadikgadi or die
The pace is beginning to tell
Fatigue pulls the close knit ranks into long straggling columns
At midday, the surface temperature is 65 degrees centigrade
Yet still the chicks struggle along step by painful step across the jagged soda crystals
The sun is merciless
already it has claimed its first victims
The rest struggle along as best they can
The exodus of the lesser flamingos has left their breeding place deathly quiet
Yet among the deserted nests and addle eggs, there is still life
This chick is hatched too late to join the migration
Its parents still fly in at night to feed it
but the innocuous looking mud is laced with crystals of caustic soda
Once mired in the quick setting mix, its fate is sealed
Even the water here is lethal
A super saturated soda solution that crystallizes on muddy legs and set rock hard,
layer upon layer in cement-like anklets
There is no escape
even birds old enough to fly are dragged down
as surely as if they were shackled with a ball and chain
Caught up in a waking nightmare, these chicks face a hopeless future
The nesting place that gave them life has now become a prison
And each night their parents still feed them
innocent accomplices in a trial of endurance with only one outcome
In the north, the long march of the flamingos is almost over
Miraculously more than 3 quarters are still alive
Nothing can stop them now
with mounting excitement those old enough to fly
take to the air as they approach their journey's end
Incredibly they have made it
Here there is water, drinkable water
For most of these birds, it's the first taste of water in their lives
In a remarkably short space of time, even the weakest regain their strength
These fragile birds have shown an extraordinary resilience by surviving this amazing journey
They will soon join the thousands of adults in the shallows
Yet even here, the water cannot last
Soon it too will dry up, leaving nothing but mirage in the hot desert air
Then one night, the flamebirds of Makgadikgadi will fly off
as mysteriously as they came into the vast African night
During the making of this film, many young flamingos died,
victims of the crystalline anklets
Normally natural history filmmakers don't interfere with their subjects
but on this occasion, Tim Liversedge and his crew could not help but act to save this baby
It was a tricky job,
the soda solution has set to a consistency almost as hard as cement
It had to be chipped and prised off
and they had to be very careful not to damage the young flamingo's fragile leg
Then the bird was released into the seemingly inhospitable waste
And Tim Liversedge was able to keep sight of that single bird
it did manage to join up with the other young flamingos on their long march
And so in all probability, it survived
Subtitles by Andrew and Hattie www.mvgroup.org