Narrator: Life in the savannas of Africa
is ruled by water.
Throughout the long dry season,
Life-giving rivers run dry,
Harsh drought conditions prevail,
And so waterholes become crowded;
At this time of the year,
the quest for water
governs the lives of all who live here.
It's winter -
the dry season
in the northern savannas of South Africa's lowveld.
And so,
competition for space in the remaining waterholes is fierce.
It's a large male Hippopotamus -
He tips the scale at almost four tons.
Water's at a premium
and males challenge each other constantly.
Losers are banished to marginal pools.
Life in the backwaters is calmer,
even if the local terrapins take a few more liberties
than this old-timer is used to.
Sometimes, the lack of water makes strange bed-fellows.
Savannas are hot and dry for most of the year.
Rain only falls during a short summer window.
Daytime temperatures regularly soar
over 80 degrees Fahrenheit.
Water is precious.
And scarce.
During the dry season grass is brown,
containing little moisture.
Small streams run dry.
Bustling waterholes shrink
and in bad years, dry up completely.
So finding water
becomes critical for the animals that call the savanna home.
Animals that eat grass
obtain little moisture from their diet,
so they need to drink every day.
Waterbuck are grazers
and are the most water-dependent antelope in the savanna.
For them the water is not only for drinking.
When frightened, water becomes their escape route.
Myth has it; the ring around their rump
comes from sitting on an open tin of white wash.
In reality
the white markings help youngsters follow their parents
through thick grass and bush.
Waterbuck rely on standing water,
so with the waterholes drying up
they must move on in search of greener pastures.
Most savanna rivers are ephemeral, or seasonal,
only flowing for a few weeks during the summer.
For the rest of the year,
these dried up riverbeds form sandy highways.
And so stagnant pools and puddles
become key water sources.
Buffalo need to quench their thirst twice a day,
and each time they'll gulp down 8 to 10 gallons.
The Red-billed oxpeckers
patrolling the buffalo feeding on ticks,
also grab the opportunity to drink.
They seldom leave their large herbivorous hosts.
With little water available,
even small puddles such as this become busy hubs.
A family of Impala is also stopping by for a drink.
Impalas are some of the most abundant antelope
in South Africa's savannas.
The Kruger National Park alone
is home to at least a hundred thousand individuals.
As such they're important prey for many predators.
Living in herds means they can watch each other's backs.
And this family needs to be vigilant.
They're at their most vulnerable when drinking.
With heads down,
they can't keep an eye on their surroundings
and they rely on others for warning.
This young female has been left alone,
but she's thirsty and determined to drink her fill
despite the potential danger.
She's a perfect target.
Every sip is a gamble.
And this
is one of the local leopard's favorite hunting spots.
Her partner returns to check on her.
His presence unknowingly saves the day.
He's driven to coral his harem
and doesn't want to lose stragglers.
Not all rivers running through the savanna
dry up in winter
some course through these parts year round.
Perennial rivers reduce their flow
but don't dry up in winter.
Hippos avoid fast flowing rivers
preferring quiet backwaters instead.
They have no sweat glands
and need to swim to keep themselves cool.
Out of the water,
they need to be careful of overheating.
This youngster is feeling the heat.
Both parents care for young hippos
until they're six or seven years old.
But his mom isn't budging.
And he's still too young, to stray far from her side.
Another savanna giant
is moving along the riverbed searching for water.
Adult elephants can weigh more than 6 tons,
making them the largest animals in the savanna.
Their skin covers a huge surface area that absorbs heat
making them dehydrate easily.
So they must drink 18 to 23 gallons of water a day
to replace lost fluids.
The matriarch leading this herd seems to have led them astray -
there's nothing here but sand.
But strong family bonds means the herd trusts its leader.
Guided by experience and wisdom,
passed from generation to generation,
the matriarch knows there is more here
than a dried up riverbed.
Under the surface water still flows in this river course.
At last everyone gets a much-needed drink.
The holes elephants leave behind in the riverbed
become important for many other animals
that are not capable of digging their own.
Not all savanna giants
need standing water to survive, however.
Giraffes consume nearly 90 pounds of leaves a day.
Their food contains all the moisture they need;
so when water isn't available they don't have to drink at all.
They satisfy their water needs by selecting the freshest leaves
and feeding in the early morning
when foliage holds the most moisture
and is covered in dew.
In general, browsing animals depend less on standing water
than grazers who subsist on dry grasses.
But this depends on the length and severity of the dry season.
Plants also fight silently against water loss.
Leaves are solar powered factories in the canopy.
And plants use water to carry nutrients from their roots
to these factories.
More than 99 percent of the moisture absorbed by the roots
is then lost by the leaves.
Plants use openings in the leaves called stomata
to regulate water loss.
Large trees will lose thousands of gallons during a year.
So trees like the Knob-thorn acacia
drop their leaves during the dry winter to reduce water loss.
But without leaves they can't photosynthesize
and so stop growing.
Other species, such as this Scented thorn,
hold on to their foliage
and control the amount of moisture
passing through the stomata.
These trees must defend their precious leaves
against hungry browsers.
So they carry sharp, needle-like thorns and piercing hooks.
This giraffe seems oblivious of the thorns however -
he's stripping leaves from the branches
with his prehensile tongue.
It's an impressive appendage
almost twenty inches long.
Microscopic horny growths on his narrow, flexible lips
also protect his sensitive mouthparts.
Giraffes are strange beasts,
simultaneously graceful and awkward,
as they slowly make their way
through the trees of the savanna.
They also use the dry riverbeds as highways
and despite not actually needing to drink,
they'll seldom pass up water if it's on offer.
The specialized blood vessels in his neck
prevent blood rushing to his head
and causing an aneurism.
For Chacma baboons the search for water is more urgent.
And the larger the troop the more water they need to find.
Baboons are remarkably adaptable primates
and move through dry riverbeds
looking for pools and puddles left behind by elephants.
Baboons get a lot of moisture
from food such as bulbs and insects
but also rely on fresh water.
In the thicket alongside the river,
youngsters find time to monkey about.
This baby is testing her nimble limbs.
While she nurses
she'll get all the moisture she needs
from her mother's milk,
but the pressure to supply enough milk
means mothers are constantly searching for the next drink.
Riverine forests are lush year round.
A Golden-tailed woodpecker is building its nest here.
They're monogamous
and both members of the pair help excavate the hole.
Woodpeckers build their nests in tall trees like this one
and rely on these trees to forage in.
Insects, ants, termites and burrowing larvae
living in the branches are on the menu.
But for the moment,
this female is more worried with the finishing touches
to nearly three weeks worth of work on her home,
than her stomach.
They drill new holes each season
and reuse holes only on rare occasions.
Their specially designed beaks dissipate the shock
and together with specially cushioned skulls
prevent brain damage.
Golden-tailed woodpeckers always nest close to standing water
and drink from puddles and pools.
Below, a small herd of kudu
are also making the most of the riverine forest.
Ordinarily males and females live apart.
But it's breeding season so they've joined forces.
Males carry impressive horns - more than three feet in length,
which they use in disputes over females.
Two and a half turns means he's at least six years old,
which makes him an old man.
Kudu live for up to eight years.
Cows are smaller and don't carry horns
because there is little aggression between females.
They also rely more on the cover of thick riverine vegetation
to avoid predators rather than an impressive defensive armory.
Kudus are browsers
and like giraffe can go days without drinking if necessary.
On the hot open grasslands,
the grazers' search for water continues.
The family of Waterbuck waits out the hot mid-day sun
in the relative shade of the thicket.
This is not a strongly bonded herd,
but rather a loose aggregation of females
often numbering as many as 30 individuals.
Waterbuck, like all antelope, are ruminants.
Their multi-chambered stomachs regurgitate food
to be re-chewed and swallowed again.
Ruminants often stand or lie in the shade
chewing the cud during the heat of the day.
Once they've chewed the plant material for the second time,
they swallow it again to be digested further in the stomach.
Rumination breaks down indigestible plant material
extracting the maximum amount of nutrition.
It also saves animals water,
because most of the moisture
also gets extracted from the food,
resulting in highly concentrated urine.
In a world where water is precious,
every little bit helps and every drop saved is critical.
Zebra are also grazers
but they have a different digestive system
from animals such as kudu and Waterbuck.
They're not ruminants
and therefore don't digest plant material as well.
They therefore need more food
than an equivalent sized antelope,
And also more water,
as less moisture is absorbed from their food.
So during the dry season,
herds form snaking columns across the savanna
as they search for water.
It's mid-day and the animals are feeling the heat.
Even this Red-billed oxpecker is struggling.
To bring his body temperature down,
he's "gular fluttering" -
opening his beak and rapidly pumping air across his throat.
The wildebeest are also parched -
their diet of dry grass has left them thirsty,
and they must march on to find water.
They join the zebra and the Waterbuck,
trekking through the sweltering bushveld
on their quest for salvation.
Water at last.
Thirsty as the zebra are, they remain cautious.
With a small foal they need to be extra careful,
as there are predators about.
The kudu have also come down to drink.
And they all have good reason to be nervous
Large crocodiles such as this one
weigh more than 900 pounds
and can be a hundred years old.
They target kudu, zebra
and sometimes even buffalo as they drink.
Once the croc's intentions are noticed
the animals give the waterhole a wide berth.
Hippos are also weary of crocs,
because youngsters are prime targets.
They'll spend up to 16 hours in the water.
Their eyes, ears and nostrils are all on top of the head,
which means hippos are still able to see,
hear and smell danger
even when they're submerged.
But underwater predators are harder to detect,
especially considering hippos even sleep in the water.
A special reflex makes them bop up and down
to take a breath while asleep.
Hippos come out of the water to warm up in the sunshine
and to eat.
Surprisingly their skin is sensitive to the sun,
so they secrete a red-colored natural sunscreen
to prevent sunburn.
And this gives them a pinkish appearance.
A troop of Vervet monkeys
is foraging along the banks of the waterhole.
They're happiest in the trees
but come to the ground when conditions are tough
and to slake their thirst.
They feed on anything
from leaves and seeds to bird's eggs and lizards,
But must drink water everyday
so they stick to riverine forests
or to the wooded areas near waterholes.
The banks of this waterhole are immersed during the wet season.
Now exposed, they're packed with nutrients.
Young grasses and shoots sprouting from the sand
are brilliant forage for the hungry monkey troop.
And conveniently close to their water source.
But the troop must keep a constant lookout for danger
when they are down on the ground out in the open.
Proximity to the water is especially risky.
But it takes a cunning crocodile to catch a monkey.
Crocodiles are not the only reptile patrolling these parts.
Nile monitors are the largest lizard in Africa,
growing more than 6 feet in length.
Their strong limbs and sharp claws
make them excellent climbers and fast runners.
He tastes his environment by flicking his long forked tongue,
identifying mates, enemies and prey.
His nostrils are high up on his snout,
just like hippos and crocodiles,
making him just as comfortable in the water.
His fin-like tail propels him through the water.
Incredibly, monitors can remain underwater
for more than an hour.
They're at home both in and out of the water;
And feed on anything they can fit into their mouth;
small mammals, fish, slugs, eggs,
birds and even baby crocodiles.
Streaks along the bank show how much the water has dropped.
It's getting cramped in the waterhole
and tempers are running high.
The territorial male has had enough.
Fights are most often lots of bravado,
but leave protagonists unharmed.
Only if they keep their guard up against the gaping jaws.
Sometimes, losers fall victim to a slash of the tusks
as they disengage from the fight.
Gashes from the lower incisors,
which are almost double the length of a school ruler,
can cause serious harm.
Hippo hide is resilient however
and even deep gashes usually only result in a few scars.
A Pied kingfisher is not distracted by the ruckus.
He weighs more than 3 ounces
and is the largest bird capable of true hovering.
When the water is low the fishing is good.
He won't turn his beak up at insects and frogs,
but fish are his principle target.
The family of hippos is warming up in the afternoon sunshine.
Spending most of their lives submerged
means ticks and other parasites
don't do well on these aquatic hosts.
So what are these oxpeckers up to?
They're notorious parasite hunters
and feed mainly on ticks.
But this time
they're feasting on something even more macabre...
The open wounds of territorial battles.
The birds peck at dead skin on the edges of the wounds
and even drink the hippos' blood,
earning them the nickname "vampire birds".
It's a double edged sword for the hippos;
This service keeps wounds clean and infection-free,
but the constant attention of the oxpeckers
delays healing significantly.
As the dry season reaches its zenith,
the landscape shrivels in the desiccating conditions.
Very little rain has fallen for months
and many waterholes now exist only as muddy puddles.
A Lesser jacana
is making the best of the difficult conditions.
His long toes distribute weight,
allowing him to walk on mud
that would be nothing more than quicksand for other animals.
This ever-shrinking stagnant pond
writhes with sharptooth catfish.
They're among the last remaining inhabitants.
Some are as big as five feet.
These hot pools are highly saline and low in oxygen.
Few other fish survive.
But the sharptooth catfish persist
thanks to a special organ above their gills.
They use this to survive the low oxygen levels in the water
by gulping air from the surface.
Able to tolerate temperatures of over 80 degrees Fahrenheit,
these fish survive in moist burrows
and wait out dry spells until water returns.
When push comes to shove they're even capable
of traveling short distances over land.
The Waterbuck family has found nirvana.
This small waterhole is fed by one of the perennial rivers
flowing across the dry landscape.
Everyone's luxuriating in the surroundings.
The dry season's ordeal is over.
There's even room enough to escape predators by swimming.
And they're not the only ones reveling
in the life-giving water.
Nearby the elephants have been satisfying their hunger all day.
But, their constant challenge is keeping cool.
Like hippos they don't have sweat glands.
Instead water evaporates through their permeable skin.
They lose half-a-glass of water every minute on hot days...
More than any other arid-adapted herbivore.
This means their search for water is never-ending.
And finding enough water to swim
makes all the difference in the world.
When they do, it's a joyous occasion.
The savannas
covering vast tracts of Africa
are ruled by water.
And the constant quest for moisture
drives each animal's life.
For them, finding water means the difference
between life and death,
In good years and bad.
After a long, punishing dry season
the scorched earth is in dire need of moisture.
But as thick rain clouds gather above,
there is hope for reprieve
as the rainy season begins once more.