All rivers are on a quest,
a constant mission to find the ocean.
An endless cycle to move water
across the vast blue planet.
Along the way they support countless lives.
But their odyssey is by no means easy.
From ice
to heat,
obstacles abound.
Yet, despite an ever-changing nature,
A river always finds its way -
on the journey
from Source to Sea.
Morning dawns across an alpine world.
This is the roof of southern Africa.
Up here, shrouded in the mist,
something very special is happening.
Clouds laden with moisture
arrive from afar
to empty their precious loads among the crags.
It's the first step in the perpetual cycling of water
that nourishes the planet.
Moisture evaporating off the Earth's surface
travels as gas in the clouds,
where it rises up,
before eventually falling back to Earth,
often in the mountains.
Indeed, mountains are where rivers are born.
And at the top of the world,
there is only one way to go -
down.
Flowing east down the mountainside,
the young river has unwittingly set course for the Indian ocean.
On the other side of the escarpment
other streams flow west,
choosing a vastly different path
that will take them across southern Africa's arid interior.
But this river has a more immediate challenge to face.
At these heights it's icy cold almost all the time
and no sooner has the water started moving,
then it's frozen solid.
Trapped in the ice wall of the waterfall,
the new river's journey draws to an abrupt halt
just yards from its source.
Yet, this morning there is the promise of something
that can unlock it from its icy shackles.
It's the beginning of spring.
For the first time in months, temperatures are rising
and the sun shines warm across the alpine world.
Drop by drop the water escapes from its frozen prison.
Gravity, the driving force of all rivers on earth,
pulls the water down the side of the mountain.
Gathering momentum, it babbles along,
picking out the rocky path of least resistance.
Under the heat of the sun,
river is born.
Small and icy,
the young river now descends
though the mountains of its birth.
It's still thousands of feet above sea level
and even the rays of springtime sun cannot thaw it completely.
Only a hardy few can handle these frigid conditions.
The first sign of animal life
is a creature not typically known
for its cold water endurance;
a tadpole.
These Maluti river frog tadpoles
seem quite at home under the ice.
The little amphibians appear to have a secret weapon
to help them survive in the frigid waters.
Antifreeze.
When ice crystals start forming on their skin
it triggers the production of glucose,
which prevents the dehydration and shrinking of cells -
keeping the little amphibians from freezing solid.
The ability to produce their own versions of antifreeze
is a talent shared by several amphibians
living in icy realms.
The tadpole's parents are close at hand.
Maluti river frogs are also known as ice frogs.
They inhabit limited ranges across the mountains.
Living in the rivers up here is their unusual choice of food -
Freshwater crabs.
The crustaceans are equally at home above or below the ice
and form a large part of the ice frog's diet.
Freshwater crabs aren't known as great travelers,
and this one will spend its whole life
along this stretch of riverbank -
Where he must sometimes sneak past sleeping frogs.
Further downstream
other waterside residents are also coming out
to enjoy the first signs of spring.
The ice rat has no antifreeze,
but it's got a few other tricks up its sleeve to help stay warm.
The social rodents make their homes beneath the earth
in burrows
of multiple interlinked chambers and entrances.
In these underground hideouts
the rats keep cozy even when it's freezing outside.
When the ice rats do venture outdoors to forage,
they have a few ways to maintain their body temperatures.
Thick fur helps a great deal,
while small ears and tails limit heat loss.
But according to scientists, their favorite way to stay snug
is sunbathing.
With a little bit of cuddling thrown in.
But for that you need to find someone
who also fancies a snuggle.
The ice rats are joined on the banks of the river
by a pair of Drakensberg rock jumpers.
They've been waiting all morning for the ground to thaw,
so they can scratch around for some breakfast.
Other avian locals soon join to feed.
Up here it's not just the early birds that get the worms.
Overhead a vulture soars.
From a height,
the twisting river glimmers like a serpent in the sun.
Continuing its descent,
it leaves the high peaks and enters freefall,
becoming an unstoppable force.
The water surges down the mountainside,
moving faster than it ever will again.
Waterfalls cascade into deep pools
hollowed out by eons of crashing flow.
The young river is well on its way now,
having left its icy origins for bubbling rapids.
The serenity of the cascades hides their true power.
Water has the ability to slice through solid rock.
Over many millions of years,
the river has carved out a path
through one of the hardest stones -
granite.
Massive boulders have scoured out cavernous holes.
But how does water cut though stone?
The answer lies both in the water's corrosive
and abrasive qualities.
The naturally acidic river water
dissolves the minerals like quartz
that bind the rock together.
Then small particles of sediment carried by the river
continuously pummel the compromised rock,
wearing it down.
These microscopic stones
chip away at the underlying rock as they move,
eventually cutting deep grooves.
In this way rivers excavate valleys,
changing the very landscape through which they flow.
The young river pushes east,
forging its way through the rocky terrain
at the base of the mountains,
towards its ultimate goal -
the sea.
But the journey from source to sea is not an easy one.
The river is about to face its biggest challenge yet.
Now as it enters the flatter lands at the base of the peaks
it slows to a crawl.
It's hotter too.
It's the peak of the dry season.
Rain is like a distant memory.
This thirsty land has sucked the river almost dry.
Here the wilderness is home to many animals,
all of which rely on the river for survival.
Few are better known for their giant thirsts than elephants.
Elephants are considered a water dependent species
and need to drink every day,
especially when it's hot.
An adult can consume upwards of 50 gallons a day,
making the demands of a thirsty herd
on the meagre river significant.
It's not only the elephants that need the river's moisture.
Camelthorn trees on its banks
use long roots to draw water from the sandy soil.
These trees in turn elicit their own visitors.
Like this troop of Vervet monkeys,
one of southern Africa's most abundant primates.
They're here for the nutrient rich seedpods.
Although the trees are epitomized
by their sharp thorns,
the monkeys seem totally unconcerned,
feeding happily among the spiny barbs.
The trees' seedpods
provide a valuable source of protein and other nutrients
for the omnivorous Vervets,
which have a wide and varied diet.
Like the elephants, the monkeys also need to drink daily,
making this riverside real estate
excellent primate property.
One upside to the dry season
is that the exposed sandy beaches
provide easy access to the water.
For this Southern white rhino mother and calf,
a visit to the river
is also an important part of their daily routine.
While the calf is only a few weeks old and still nursing,
mum needs to drink
in order to produce gallons of rich milk.
Each new generation of white rhinos is invaluable,
for it helps secure a future for the highly endangered species.
After facing near extinction in the nineteen sixties,
population numbers are still very low
and every healthy rhino baby like this one
is a small conservation victory.
The little calf is still very reliant on her mother
for protection and support.
Mum is in turn an attentive and capable parent.
Few predators would dare challenge her -
3,700 pounds of muscle and thick hide behind a smooth-tipped horn
are intimidating to even the biggest lions.
But there are some things in a young rhino's life
even her mother can't help with.
Like ticks.
She's covered in them.
Luckily for the calf, in nature if there's a job to be done,
there's generally someone to do it.
Oxpeckers have identified tick cleaning as a niche market.
The little bird gets to work on the infestation.
It's a win-win situation for bird and beast.
Treatment complete,
the industrious birds move on to mum.
Further downstream, a group of vultures has come to the water
for a seemingly unlikely reason.
While the birds have a reputation
for being dirty scavengers,
these White-backed vultures are here for a bath.
Like all birds,
they need to keep their feathers free of excess oil and dirt
so they line up for a wash.
Next they assume open winged poses to dry off in the sun.
It's a routine cleaning that ensures they're in tip top shape
when it comes time to take to the skies.
From above the vultures look for carcasses to feed on,
for they don't hunt themselves.
But they're out of luck this morning.
The only predators around
are more interested in a nap than a kill.
African wild dogs may be
some of the most successful predators on the continent,
but right now it's too hot for them to hunt.
Like wolves they're extremely social animals,
living in groups governed by an alpha male and female.
The dogs once ranged widely across sub-Saharan Africa,
from mountainous areas to desert.
Nowadays they are considered endangered,
with only an estimated 39 sub-populations left
within Africa.
Around a bend of the desiccated river,
another threatened species makes its way.
The African elephant
is also facing critical population losses.
Like the wild dogs,
elephants need vast amounts of space to roam and feed in.
Theirs is a restless and nomadic life,
always on the move in search of food, water and mates.
And the river is an important part of their journey.
They use its winding path like a road,
mapping out the easiest migration routes
between feeding grounds.
Staying close to the river
ensures they have access to water,
which they need for more than just drinking.
The huge mammals keep cool
by taking regular mud baths along the way.
Mud bathing is common practice for elephants,
keeping their surprisingly sensitive skin protected
from both the sun and parasites.
Down the way,
where the waning river is little more than a dirt pit,
there's another mighty herbivore with an affinity for mud.
This buffalo bull is a senior citizen.
Retired from a position at the head of the herd
now relegated to a life of solitude on the riverbanks.
But he's not alone today.
He's being watched
by a pair of Africa's most powerful predators.
A young male lion
and his brother.
They might not have full manes yet
but they've got the power to pull down the 1,900 pound bull.
The ambush hunters hunker down.
They need him to get close enough for them to pounce.
He can't see them.
But he can smell a trap.
This old bull has lived through many a lion hunt.
Experience tells him to beat a hasty retreat.
The savanna kings will have to look elsewhere for their dinner.
In the greying evening sky,
a rumble of thunder signals an end to the dry season.
After months of thirst, the rain soaks the land,
bringing respite and rejuvenation.
Dawn beaks to reveal a fresh and renewed world.
Further downstream, the effects of the rain are visible
as swollen tributaries feed the river,
which grows deeper and wider than ever before.
Flowing along in this fashion,
it leaves the wide open plains and rocky hills of the bushveld
and enters the tropical coastal zone.
Closer to the Indian ocean,
both the river and the surroundings change once more.
The river relaxes into a languid stillness,
widening across its flood plain and depositing rich sediment
that fuels abundant growth around, and within.
Water birds make a good living fishing in the rich waters.
The regal heron uses a long beak to spear unsuspecting fish.
While the king fisher dive bombs his quarry.
There's another bird here
that prefers the wetland's side salads to fishy mains.
The Palm nut vulture is not what you'd expect a bird of prey.
While the smell of rotting meat would excite its cousins,
this vulture prefers the vegetarian menu.
It lives mostly off the fruits of the Palm nut tree.
There are others around
who also favor the easy pickings of the Palm nuts' bounty.
Samango monkeys share the big birds' enthusiasm for palm nuts.
Also called Blue monkeys, they are rare in southern Africa,
only living in coastal forests like this one.
These Samangos have made excellent waterside homes here,
with quirky neighbors
and plenty of food.
On the calm surface of the river, beauty blossoms.
Water lilies are well suited to a life aquatic.
Their wide, round leaves float on the surface
while long hollow stems reach down to the river floor.
It's the lilies' flowers that are the most alluring.
Their perfume and bright colors
are simply irresistible to many insects.
But the lilies serve other river locals besides the bees.
They provide the perfect hunting platform
for one very unusual creature.
These long legs and spindly claws
belong to the African jacana.
This striking bird has evolved long, thin feet, which enable it
to distribute its weight evenly over the lily pads,
so it doesn't sink
while searching for insects among the leaves.
These three are a family unit,
but not the kind you'd necessarily expect.
This bird is a single dad.
Jacanas are unlike most birds insofar as
it is the male who cares exclusively for the chicks.
The chicks' mother may have mated with multiple males,
leaving each one with a clutch of eggs to raise on their own.
This unorthodox system of breeding
evolved to compensate for an extraordinarily high rate
of egg loss to predators.
The world of the jacana has, in effect,
turned the female into an "egg-making machine,"
leaving the fathers to incubate and care for the eggs.
This dad has done his duty well.
He's got not one but two healthy fledglings that are learning
how to navigate a life of walking on water.
The main thing they need to figure out is how to catch food,
without sinking.
So far so good.
As the river moves closer to the Indian ocean,
strange shapes appear within.
Indeed, it's not only wildlife that uses these waterways.
Fish traps provide for subsistence fishermen
who have long lived off the coastal estuaries.
This ancient method has been passed down through generations.
It's carefully designed to guide the fish through a passage
and into the heart-shaped trap.
The structures are built so that only big fish get trapped,
while small fish can move in and out.
This form of fishing remains sustainable,
striking a balance
between the needs of the people that live here
and the conservation of those species
that use these waters to breed.
During the summer months, the river is full of fish
with species like bream, grunter and mullet
finding their way into the traps.
But now, at the start of spring, large fish have yet to arrive.
Like all fishing endeavors there is no guarantee of success.
Sometimes fishermen must contend with more than bad luck.
Other riverside locals sabotage their traps.
The calm, shallow water is perfect for hippos.
These amphibious mammals are incredibly strong,
and have been known to trash the fish traps on a whim.
Below the surface, the fish benefit.
This trap can hold them no more.
At last, the ocean is within reach.
Yet here the river goes through one of its most extreme changes.
This close to the ocean
the very make-up of the water is changing.
Mixing with the salty sea
it has become, for the first time, saline.
While the brackish water
would be too extreme for most plants to survive in,
one very unusual tree still thrives here.
Mangrove trees are uniquely designed
to survive in salty water
with roots that penetrate the mud at low tide,
acting as snorkels during high tide.
They also employ a complex filtration system
to keep out most of the salt.
Their success in this difficult habitat
in turn supports others that call this coastal zone home.
Crabs feed on fallen debris from the trees,
scurrying to the safety of their holes when threatened.
Their constant gardening
recycles nutrients back into the earth,
fueling the growth of more mangroves.
At high tide
the trees also provide a shelter for numerous juvenile fish.
These crowd around fallen branches,
keeping out of sight and out of danger.
One day they will be big enough to follow the river
on the final leg of its journey
out into the ocean.
Once past the mangroves, the river finally meets the sea.
At the mouth it spills into the warm Indian ocean,
bringing with it nutrients
to feed those living on the inshore reef systems.
Here, finally the river ceases to be separate from the ocean.
Beyond the waves,
life flourishes along vivid coral havens.
It's an excellent example of a healthy estuary
feeding into a vibrant ocean,
where marine life can live and breed in abundance.
This river's journey
has taken it past a myriad of landscapes and characters.
The water it carried has floated high over the mountains,
quenched giant thirsts,
and cut through rock.
Now it has come to rest in the mighty Indian ocean.
But its quest will not stop there.
One day, in a place far away,
the same water will embark on another epic journey -
from Source to Sea.
♪♪