Lake St Lucia...
One of South Africa's greatest wetlands.
This sliver of life-giving water
offers relief in a land stricken with drought.
But, even this oasis is fragile...
And without rain
the wetland is drying.
Both the plants and animals living here
are finding new ways to cope
with their ever-changing world.
The landscapes of southern Africa
are home to a rich tapestry of life.
Plants and animals can flourish.
This is usually a land of plenty.
But for the last 20 years,
the area has received below average rainfall.
A drought is wreaking havoc throughout the region.
The dry deserts in the west
and the typically moist savannas in the east
are equally affected.
Life is struggling.
Once mighty rivers are now sandy beds.
And more than ever,
wetlands are critical magnets of life,
breaking up the parched surroundings.
Throughout the world,
wetlands can be some of the most
biologically rich habitats on earth.
Animals across the region rely on these oases.
Lake St Lucia, South Africa's most important wetland,
lies in the iSimangaliso Wetland Park
on the east coast...
It's Africa's largest estuarine lake.
This 135 square mile lake
has a mosaic of habitats along its borders.
Amphibious hulks crowd in the pools,
forming the largest hippo population in South Africa.
And some bird species migrate from over 6,000 miles away
to spend the summer feeding and nesting
along these bountiful shores.
It's a wildlife mecca.
Covering just 6% of the earth's surface,
freshwater wetlands like this
support one third of all species.
But without rain
some areas of the lake are now completely dry.
Rivers flowing into the system
are no more than fading trickles.
And the animals that rely on standing water
are concentrated into the ever-shrinking area.
The surrounding marshes are the only patches of green
for miles around.
It's January in iSimangaliso.
This is ordinarily the wet season around Lake St Lucia.
Historically,
this region receives nearly three times more rain
than the rest of the country.
But, this is the driest Lake St Lucia has been
for 65 years.
While there may be an air of sterility in the weather,
this isn't the case amongst the animals.
New life flickers across every habitat.
The lake isn't what it used to be,
but it still provides enough for these newcomers.
With every passing day,
this baby hippo grows in confidence.
He's less than a month old
and won't stray far from his mother's side.
Despite her languid appearance,
she's very aggressive
and protects him from predators and older pod mates.
Hippos only give birth to 1 calf every second year,
so mothers are fiercely vigilant with their young.
This calf weighs around 110 pounds,
which is nothing compared to the one-and-a-half ton bulls.
His mother will nurse him for just under a year,
keeping him close by her side at all times.
He's adapted to life in water
and is able to latch onto her teat and drink while submerged.
For now, he'll spend most of his time in the safety of the lake,
alongside mom.
Reed beds along the lake's shores
provide protection for other juveniles.
This young red bishop is fledging.
Once his adult feathers have grown in, he'll be on his own.
But for now, he's still under his mother's care.
Normally a seed eater,
she picks a spider from the stems for her growing youngster.
Spiders are rich in protein and fat
to help fuel his growth.
In the water below
a pair of red-knobbed coots feeds in the shallows.
They're after the stems, shoots and seeds of aquatic plants.
By eating old decaying stems
they get a meal,
and they also clear the reed bed of rotting vegetation.
It's win-win for the reeds and the birds.
Reed beds are vital to the wetland.
They trap floating sediment,
helping to filter the water
before it flows into the main body,
Absorbing excess nutrients and other harmful chemicals.
These are then either stored in the waterlogged soil,
or slowly released back into the air.
Wetlands are nature's filters
the kidneys of the environment.
The reed beds are functioning normally,
but this isn't the case everywhere.
The past century has disrupted St Lucia's natural flow.
The lake was once fed by two sources;
the Mfolozi River and the ocean.
With a constant freshwater source and an outlet to the sea,
it was a thriving estuary.
Shorebirds of all shapes and sizes probed its tidal mudflats.
But in the early 1900s, this all changed
The marshes around the estuary's mouth
were turned into sugarcane farms.
Nobody understood the vital services
these wetlands provided.
Without marshes to filter sediment,
the sugarcane fields became blocked up and flooded.
To deal with this,
managers diverted the Mfolozi River away from Lake St. Lucia.
With no freshwater source, and decreasing rainfall,
the lake's water levels dropped,
and the channel to the ocean closed.
Lake St. Lucia is cut off from both the Mfolozi River
and the ocean.
Without seawater the lake has become less saline.
And freshwater vegetation has spread throughout.
Some species are reaping the rewards.
Back in the reed beds
a yellow weaver is starting work on his new nest.
He carefully weaves every blade of grass together
to form his home.
He's a born craftsman.
But it's a skill that takes time to perfect.
Young males construct nests faster
when they're surrounded by more experienced weavers.
This male has already honed his skills.
So he's building his nest in a secluded spot.
Yellow weavers live here year-round.
Other birds are more seasonal.
This reed warbler
has been in South Africa for about two months.
He's flown down from north Africa to take advantage
of the southern hemisphere's temperate summer.
He's here to make the most of the summer insect bloom.
He'll stay for another month or so
to breed and replenish his stocks
before making the arduous flight back home
just in time for northern hemisphere's spring.
60 miles to the north of Lake St Lucia
lies another wetland jewel -
Kosi Bay.
Unlike St Lucia, this estuary remains open to the sea,
so the mangroves are functioning normally.
Salty water inundates the forest twice a day.
These trees are well adapted to the tide's constant flux.
Aerial roots act as snorkels,
allowing the trees to breathe.
Marine fish swim through the estuary's mouth
to lay their eggs amongst the mangrove roots
in the sheltered lake.
When the eggs hatch,
the juveniles remain in the confines of the estuary
until they're developed enough to venture out into the ocean.
When they're ready, they start their lives on the reefs
and in the oceans bordering the shoreline.
Back in St Lucia,
a sandy beach now stands
where the lake's mouth used to enter the sea.
Separated from the ocean,
it no longer supports vibrant mangroves,
nor populations of marine fish.
The lake's relationship with the ocean is severed
and the mangroves are now eerily quiet.
Not all forests in St Lucia are suffering however.
On the floodplain away from the shore,
a troop of vervet monkeys
is taking a midmorning break from foraging.
Vervets get most of the moisture they need from their diet,
so they rarely drink water.
They're opportunistic
and eat anything from seeds and fruit
to eggs and insects.
And adapt to the prevailing conditions.
If the drought becomes too extreme,
they'll simply move somewhere else.
But for now, this troop seems content in the wetland forest.
Babies are cherished members of vervet society.
They experiment with social dynamics through play.
The troop protects them,
so it's a safe space to monkey around.
While the mood is light-hearted in the vervet troop,
this isn't the case in the slowly shrinking lake.
The receding water levels
are forcing the lake's thousand or so hippos
to hang out in much closer quarters than they'd like.
These amphibious mammals are adapted for life
on both land and in water.
Their ears and nostrils seal off when they submerge.
Although they spend most of their time in the water,
they can't actually swim.
Their bodies are simply too dense to float.
To move around they trot along the bottom of the lakebed,
as graceful as astronauts on the moon.
For now,
Lake St Lucia provides this pod with everything it needs
Water deep enough to submerge in the heat of the day,
and plenty of food at night
on the grassy plains surrounding the wetland.
But as the drought continues things are changing.
The average depth of the lake is already only a measly 3 feet,
and is steadily decreasing.
Without rain, the water levels will fall,
bringing the hippos closer and closer together,
and the surrounding grasslands
will become overgrazed and desiccated.
Some members of the pod have started feeding
during peculiar hours.
Ordinarily
hippos only come out of the water
to graze at night.
Their sensitive skin
can't handle the harsh African sun.
But with the grass in short supply
this bull has been forced to graze during the day.
Another of the lake's heavyweights
is reaping benefits in the conditions.
Nile crocodiles are the largest in Africa
and can grow up to 20 feet.
But here, they're particularly plump.
The shrinking lake
is squeezing the freshwater fish into a smaller area.
And this is good news for the massive reptiles.
Their hunting grounds are smaller
and more concentrated with prey.
And this female's stomach shows the effect of this abundance.
Fish are their most important food in St Lucia.
While larger fish are vulnerable to crocodiles,
the smaller fish have a strategy to avoid their avian predators.
Young tilapia gather in the shallows.
This keeps them safe from two different groups of fish eaters.
Predators from the air, like the pied kingfisher,
aren't able to attack them with aerial dives
in such shallow water.
And it's not deep enough
for divers like the Little Grebe to sneak up on them.
Despite these strategies,
freshwater fish still provide a reliable food source
for most birds.
They're a key component of this ecosystem's food web.
Lake St Lucia is the heart of waterbird activity
in South Africa.
With so many species crowding the lake,
each must find a different way to catch its food.
Some use a random stabbing method,
While others perch and wait,
using their keen eyesight to plan their attack.
A yellow-billed stork wades through the shallows.
With his beak submerged
he stirs up the mud, and potential prey, with his feet.
His highly sensitive bill
will snap shut at the slightest movement.
While the stork prefers to fish alone,
others tend to hunt as a group.
Great white pelicans feed in a similar way to dolphins.
They surround a school of fish, herding them into the center.
Then they plunge their heads into the water,
gulping up large volumes of fish,
storing them in their expandable bills.
Not all waterbirds target fish.
Greater flamingos stomp around in circles,
uncovering any crustaceans that may be hidden in the mud.
Their bizarre looking beaks then filter the muddy soup.
They pump their tongues like a piston,
flushing out the water and sediment through the beak.
Hair-like structures, called lamellae, filter out the food.
Their prey contains organic pigments called carotenoids.
These pigments color the birds pink,
best displayed when they take to the air.
But perhaps even more impressive is the pied kingfisher.
This is the largest bird capable of true hovering.
He weighs almost 4 ounces,
50 times more than a hummingbird.
As the day wears on, it's time for a little afternoon shut-eye.
It's also nap time for the hippos.
And no other mammal in St Lucia
seems to enjoy an afternoon siesta more.
But these supposedly docile behemoths
have a very different side to their character.
And it's never good to wake a sleeping giant.
Dominant hippo males are extremely territorial
and each beach master will defend his turf aggressively.
They're also responsible
for around 3,000 human deaths a year across the continent
This is Pumba.
He's the dominant male in this pod,
named by the St. Lucia locals.
His unusual warthog-like tusks
have helped him fight his way to the top.
Every male carries battle wounds
that attest to the species' violent nature.
If other males don't show submission to Pumba,
by wagging their tails and bowing down to him,
he'll perceive it as a challenge, and will attack.
Hippos are violently territorial
but even they have to accept some lurking neighbors.
Crocodiles are the largest reptiles on earth.
And they're well adapted to life both on land
and in water.
Their nostrils and ears seal off when they enter the lake.
And a thin membrane coats their eyes, enabling clear sight.
A special valve on the back of the tongue
closes off the throat when they're submerged,
so water doesn't enter their stomach or lungs.
And they have a unique heart anatomy.
Unlike most reptiles,
they have a four-chambered heart.
They also have an extra aorta,
diverting blood flow away from the lungs.
This allows deoxygenated blood
to mix with oxygenated blood when they're underwater,
allowing them to spend up to 2 hours without breathing.
They're the undisputed apex predators of Lake St Lucia.
And they have one more trick up their sleeve.
These black pores are sensitive pressure receptors
that detect even the tiniest motion in the water
while they're submerged.
A heron foraging in the shallows is a promising target.
They may be supreme killers
But they're not always successful.
While crocodiles are top of the food chain in the water,
another reptile hunts life around the lake.
A Nile monitor stalks the muddy shoreline.
He's one of the largest lizards in Africa and he's on the prowl.
Anything from birds eggs to small mammals are on the menu.
And swamp hens are good eating
if he can catch one.
But they're not the easiest targets.
Although this one hasn't spotted the monitor,
a continuous flick of its white tail tricks the predator
The lizard thinks he's been spotted,
so he moves onto less attentive targets.
And the oblivious swamp hens continue foraging.
Theses wetland locals are omnivorous.
Today they're after a vegetarian diet.
With extra large feet, about a third of their body size,
they can walk across the mud without sinking.
They use their oversized claws
to snap off, and rip apart grasses and stems,
so they can access the soft fleshy parts inside.
In the marshes fringing the banks
a herd of Kudu is taking advantage
of the only greenery for miles around.
Wildebeest and buffalo also seek refuge
from the parched savannah.
These swathes of green
risk becoming overgrazed
as more and more herd mammals concentrate here.
The waterlogged land provides grazers with more than food
A roll in the mud
helps alleviate the stifling temperatures.
The cooling mud also helps keep irritating insects at bay.
As the drought intensifies,
the heat becomes unbearable for everyone.
The buffalos aren't the only ones being pestered.
A woolly-necked stork preens on the banks.
And they've developed an ingenious way
to get rid of parasites.
They spread their wings.
While this is a common strategy to warm up,
the storks aren't doing it because they're cold.
Instead, they overheat their black feathers,
ridding themselves of any lingering parasites,
which can't take the heat.
While some fight a lone battle against irritating freeloaders,
others get a helping hand.
A red-billed oxpecker
is picking ticks from this female kudu.
And they're especially useful
in getting to those hard-to-reach places.
She tolerates the groomer
For the most part.
The mangroves of Kosi Bay, north of Lake St. Lucia,
flush with nutrients
as the tide rises and falls.
With the tide out, the mudflats come to life.
Mangrove crabs emerge from their burrows
to feed on fallen leaves and seeds
While mudskippers brave dry land
in order to hunt insects.
But further south in Lake St Lucia
this is no longer the case.
Without a tidal flow,
the mangroves are forlorn skeletons
of their former selves.
The mudflats are long dry,
and can't sustain life.
Crab holes stand empty,
and formerly flooded roots lie exposed.
The trees hang on
because their roots reach deep enough
to tap into what little water remains underground.
But the true spirit of the forest is gone.
Back in the reeds,
the lone yellow weaver has almost finished his creation.
As soon as he's done,
he'll flap his wings outside the nest
and wait for a female to inspect his handiwork.
Nearby a colony of southern masked weavers
is already a long way through their house building...
Which is looking more and more like an apartment block.
They prefer tree branches for their nests.
And just like the yellow weaver -
while the males build,
the females judge.
When a female finds a nest she likes,
she'll enter and layer it with leaves.
This is her way of accepting the male, and they'll mate.
Soon after, she'll lay her eggs,
and wait for her chicks to hatch.
Females prefer nests made of green, fresh material.
And this male has made a mistake
He's crafted his masterpiece out of dried grass.
And he's not getting any takers
So he destroys his design.
And it's back to the drawing board for him.
Only then will his new chicks be born into the wetland system.
As the sun starts to set over the lake,
the mood amongst the hippo pod changes.
They become restless.
Their stomachs are calling
and it'll soon be time to venture on shore to feed.
Then it's every hippo for itself.
For now, the pod is coping.
But as the drought continues, it will test the limits
Of the wetland wonder of St Lucia.
Lake St Lucia provides food and shelter to a menagerie of life.
But it's under siege from a sustained drought.
This, together with human missteps,
means the water is at dangerously low levels.
And the estuary is cut off from the sea.
Only a large flood of freshwater
will break open the mouth once more.
Allowing balance to return
with the ebb and flow of floods and tides.
For now, the plants and animals of this oasis must
adapt to a changed world
And hang on until this resilient wetland wonder
returns to its former glory.
♪♪