♪♪ NARRATOR: In southern Kenya lies a remote desert kingdom, home to a cast of remarkable wild creatures.
They owe their existence to an extraordinary relationship between the largest animal and the smallest, a relationship of provision and dependency that has flourished for millennia.
Together, elephants and termites create water holes -- animal oases that are miracles of life.
♪♪ This is the remarkable story of a water hole in Africa, the animals that created it, and those that call it home.
♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ NARRATOR: Without water, life has no chance to join the desert in its dance.
For here, where sun and wind hold sway, when water comes, it cannot stay.
♪♪ ♪♪ ♪♪ This is Tsavo, one of Africa's last great wildernesses.
♪♪ It's an arid land, yet rivers of sand hint at something different.
[ Thunder rumbles ] It rarely rains, but when it does, a year's worth can fall in just a few hours.
[ Thunder rumbles ] Most of it will run away, destined for the Indian Ocean, channeled by sand rivers that flow for just a few days each year.
♪♪ They connect to the mighty Galana, which will carry the rainfall away.
♪♪ [ Water crashing ] [ Elephant snorts ] For the water to stay and benefit wildlife, requires the services of the largest animal here, and also the smallest.
♪♪ Together, elephants and termites create water holes.
♪♪ For thousands of years, their partnership has transformed some of the driest regions in Africa.
[ Elephants trumpeting in distance ] It all starts with a termite mound.
The clay the mound is made of is manufactured by worker termites deep underground and then brought to the surface.
It is a sticky mixture of organic material, minerals, and water -- the perfect building material, which will set hard like concrete.
Compared to the surrounding soil, the clay is packed with nutrients.
[ Birds calling in distance ] A termite colony might live for decades, but for our story, what's important is what happens to the mound when a colony dies.
It can take years for it to erode, but elephants, rain, and wind will eventually prevail.
Then all that is left is another clay scar in the landscape.
♪♪ Every scar here was once a termite mound.
They're a focus for elephants, as the patches of clay are what elephants love.
Tsavo's ancient red soils are deficient in the salts elephants need, but termite clay contains them in abundance.
Their constant excavation means that, little by little, the site of the old mound becomes a hollow in the landscape.
When it rains, the fine clay dust turns to sticky mud... [ Chuffs ] ...and, for a family of elephants, that is irresistible.
[ Chuffing and trumpeting ] Besides keeping them cool, a coating of clay protects against sunburn and biting flies.
Once elephants start to wallow, a water hole's future is assured.
Each time a family visits, it carries away up to a ton of mud, and so the hole grows.
[ Trumpeting and chuffing ] After a year or two, the young water hole can hold enough water to invite daily visits.
[ Grunting and chuffing ] ♪♪ Within a few years, what the elephants engineered, with a little help from the termites, will become an oasis, which all will visit and some will call home.
A water hole can last a century, but each year it must go through a seasonal cycle of decline and rebirth.
This is the story of one of those seasons.
♪♪ [ Thunder rumbles ] ♪♪ What sets it all off is a direct hit from a thunderstorm.
[ Thunder rumbles ] Then the paths that the elephants made funnel the water down to the water hole.
♪♪ ♪♪ Insects are the first to move in.
[ Insects chirping ] Dragonflies pair up to lay eggs.
[ Elephant trumpets ] It doesn't take long for the heavy lifters to arrive, and some of them carry passengers.
[ Bird calling ] Tiny eggs arrive on elephant feet.
[ Elephant chuffs ] Once underwater, they hatch into baby killifish.
♪♪ ♪♪ ♪♪ One character has waited months for the water to return.
A lungfish spends each dry season asleep underground.
It's a living fossil, a fish with primitive limbs that breathes air.
And now there's water, every few minutes it must surface to breathe.
[ Insects chirping ] At this stage in its life, the water hole is well on its way to becoming an oasis.
Seeds arrive in elephant dung, and grasses and bushes will follow.
[ Insects chirping ] For yellow-billed storks, a full water hole heralds a time of plenty.
Their beak snap is the fastest reaction in the animal kingdom... but the lungfish is strong and has powerful jaws.
And it's quite prepared to bite back.
[ Squawks ] [ Squawks ] ♪♪ Compared to lungfish, killifish live fast and die young.
This female hatched from an egg and matured in just two weeks, but to have any chance of spawning, she must keep a low profile.
♪♪ ♪♪ It's not an option for males.
To attract the attention of a female, they must fight and display where they're most visible.
♪♪ ♪♪ The female signals her choice by allowing a male to approach.
Now that she's chosen him, he'll dance just for her.
♪♪ They must seize the day.
They have no way of knowing how long the water will last or what the future holds.
♪♪ [ Ominous music plays ] ♪♪ [ Birds calling in background ] As the water hole matures, it attracts different characters.
[ Hooting ] [ Snorts ] Some come to bathe, others to drink... ...and some to hunt.
[ Birds calling in background ] [ Trumpets ] For as long as there's water, elephants are an enduring part of the water hole's story.
The old mound is long gone, but the minerals the termites brought to the surface are now dissolved in the water, so the elephants continue to benefit.
♪♪ Their visits are vital, both for what they take away and what they leave behind.
Elephant dung is the foundation of a pyramid of life.
A dung beetle can smell it from a mile away.
He's one of the water hole clean-up crew who'll find the dung by zig-zagging upwind to stay in its scent plume.
♪♪ He's last to the party, but that's an advantage.
Others have already made their dungballs.
He just has to steal one.
♪♪ ♪♪ And for this little thief, karma comes in the form of a bat-eared fox.
♪♪ [ Yipping ] ♪♪ Now that there's water and food, the water hole attracts life from the grasslands around it.
♪♪ There's enough salt left in the dung for butterflies to drop in for a drink.
♪♪ They use a flexible proboscis.
It's a combination of sponge and drinking straw.
♪♪ ♪♪ A female slender chameleon is a water hole regular.
♪♪ ♪♪ The butterflies are more than a salty snack.
They are full of protein, and she needs to pack them in while she can.
♪♪ [ Birds calling, insects chirping ] The water hole gives life, and occasionally it takes it away.
If the water level gets too high, it can threaten living termite colonies.
♪♪ ♪♪ ♪♪ These are soldier termites.
Their job is to protect the colony.
But against water, there is no defense.
♪♪ With the galleries flooding, the termites are forced to evacuate.
♪♪ ♪♪ Some soldiers stayed to the end, but their sacrifice was in vain.
♪♪ ♪♪ [ Birds calling in distance ] Young bullfrogs are water hole big-mouths and always on the lookout for food.
The worker termites are defenseless against them.
But the soldiers are armed with formidable jaws.
There's a technique to eating them, which some get immediately.
Others have to learn from experience.
The water hole is both larder and nursery for bullfrogs.
Adults mate after heavy rain, but it's a race against time.
In this ephemeral world, the only certainty is that the water hole will eventually dry.
[ Bullfrog croaking ] The female lays a sheet of eggs.
♪♪ To survive in temporary water holes, bullfrog tadpoles, like killifish, have evolved one of the fastest growth rates of any animal.
They hatch within hours, and if the water lasts, in just two weeks' time, they will change into tiny bullfrogs.
♪♪ The water hole's wet season is when most animals breed.
With male chameleons, it's not dancing ability that determines who gets to mate.
It's a wrestling match.
[ Chameleon snorts ] [ Snorting ] [ Hisses ] [ Splash ] One fall, and he's out.
The water hole's flush of insects has brought the female into breeding condition.
She will mate just once and lay her eggs in a few weeks' time.
♪♪ The water hole's inhabitants don't yet know it, but 30 miles away to the north, there has been a decision that will affect all their lives.
Ten million red-billed quelea have paused in their migration and decided to nest.
[ Birds calling ] The colony has synchronized its nesting to the day.
In a week, the youngsters will all fledge together, and then they'll be on the move.
It won't rain again now, and the water level has started to fall.
♪♪ The mound the termites abandoned might not look much of a threat, but to a dung beetle, it's a mountain whose slopes are covered with pitfall traps.
♪♪ A dung beetle is a walnut-sized package of determination, but he is also upside down pushing backwards, so he can't see where he's going.
♪♪ ♪♪ ♪♪ Dung beetles are nothing if not tenacious.
And for an animal that the ancient Egyptians thought so powerful that it rolled the sun around the Earth, this is a temporary setback, not a crisis.
♪♪ ♪♪ ♪♪ ♪♪ The termite mound might be a magnificent testament to insect social housing, but in some ways, it's more like a pinball machine.
♪♪ ♪♪ ♪♪ As the water recedes, the banks it exposes are what the chameleon's been waiting for.
[ Birds calling in distance ] Now that there is no chance of flooding, she'll lay her eggs.
Her parental responsibility ends with covering them up.
The eggs will develop over the next few months... ...and hatch when the next rains come.
[ Bird calling ] Water holes are always a focus for predators.
But, size for size, there is one here who is more powerful than any of them.
It's not a big cat, but a spider.
♪♪ The bullfrog tadpoles are about to change into frogs.
They've just developed lungs, so now they must come to the surface to breathe.
It's what the water hole's fishing spiders have been waiting for.
♪♪ ♪♪ ♪♪ ♪♪ ♪♪ A tadpole is 10 times a spider's weight and much stronger.
But if the spider can hang on, she has venom on her side.
♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ Away to the north, the quelea have fledged.
[ Birds calling, wings flapping ] Tomorrow, they will arrive at the water hole.
[ Animal growling ] ♪♪ ♪♪ It starts like any day.
But the birds are on their way.
Quelea are the most numerous birds on the planet.
They visit the water hole at the start of the dry season... ...when the grasslands have just set seed.
[ Flock thundering ] A flock can drink 2,000 gallons a day.
So great are their numbers that it draws predators to the water hole from all over Tsavo.
[ Birds calling ] It's rare that a lanner falcon loses its grip... [ Birds calling ] ...but one predator's loss is another's gain.
The falcon won't give up.
Its technique is to apply pressure to force a mistake.
[ Chirping frantically ] Even a terrapin is tempted to give it a go, for the more the quelea drink, the shallower the water hole becomes.
A steppe eagle isn't quick enough to catch quelea.
But he is quick to spot an opportunity.
The terrapin has a quelea by the legs.
But he's about to find out he's bitten off more than he can chew.
♪♪ ♪♪ ♪♪ ♪♪ ♪♪ The odds of the quelea being caught were probably 1 in 10,000.
♪♪ The odds of it escaping twice are closer to 1 in 10 million.
But sometimes, that's all you need.
♪♪ [ Birds calling in distance ] As the land around the water hole dries, one of Tsavo's rarest plants flowers.
Marsh lilies open at night and last just a few hours, so the bees are up early.
[ Buzzing ] ♪♪ The water hole's sacred lilies are different.
They spend the night closed and then open by day.
♪♪ ♪♪ ♪♪ Occasionally, they have guests who have spent the night inside.
Quite why the tiny Thumbelina frogs do this is a mystery.
♪♪ [ Buzzing ] But bees love the lilies for the pollen they produce.
So for the little frogs, there is no chance of a lie-in.
[ Buzzing ] The killifish have slowed down, which gives a water scorpion the chance it's been waiting for.
The fish have been spawning for weeks, and they are exhausted.
♪♪ ♪♪ The water hole is now the only source of water for miles around, and with so many using it, will last just a few days.
♪♪ ♪♪ Over time, a water hole's popularity can lead to its downfall.
If too many visit or stay too long, they destroy the vegetation, and erosion follows.
♪♪ What was once an oasis can then turn into a dustbowl.
♪♪ [ Barks ] [ Birds calling ] If more soil washes in than the elephants remove, then the water hole's fate will be sealed.
For now though, the elephants are keeping it open.
[ Elephant chuffs ] As the dry season progresses, food becomes scarce.
No one can afford to let an opportunity pass by.
[ Birds calling in distance ] An orb spider's web is so strong, it can trap flying birds, let alone a plump baby bullfrog.
The web needs repairing, which brings the spider down close to the water.
But what she needs to be aware of is that bullfrogs come in all sizes.
♪♪ In the space of a few weeks, the water hole has been transformed.
The only life that remains is confined to a few elephant footprints.
♪♪ ♪♪ The lungfish must move now.
It uses its powerful jaws and primitive limbs to leave the water in the same way that its relatives did when they colonized the land hundreds of millions of years ago.
[ Inhales ] It will bury down to spend the dry season safely cocooned in the mud.
The terrapin and water scorpion will move on.
The killifish will die.
They mated until the end.
It ensured that buried in the mud beneath them is new life... ...killifish eggs that will hatch when the next rains come.
♪♪ Close by, the lungfish is aestivating.
Its metabolism has slowed to a rate just sufficient to keep it alive.
It can survive like this for up to five years.
The chameleon's eggs are safe but entombed.
All are waiting for rain.
♪♪ The water hole is now just a clay scar in the landscape.
♪♪ Without water, the flocks and herds must move on.
[ Barking ] Only the elephants can stay longer.
♪♪ Their matriarch remembers where she dug for water years before.
And she can smell where it lies beneath the sand.
[ Chuffs ] Elephants prefer clean water.
No matter how thirsty they are, the first dirty trunkful is discarded.
[ Chuffs ] [ Birds calling ] In the dry season, the role of clearing up elephant dung changes hands.
For months, dung beetles have been the water hole's major recyclers.
Now termites take over, and this benefits a new cast of characters.
♪♪ ♪♪ So, even in the dry season, elephants and termites continue to provide for those that live here.
♪♪ It is at the height of the dry season, when Tsavo is at its most desperate, that the Rainbush flowers.
How it predicts the coming rain is unknown.
Perhaps it's a change in pressure or humidity, but it is never wrong.
♪♪ ♪♪ ♪♪ ♪♪ [ Thunder crashes ] ♪♪ [ Thunder rumbles ] The rain will release those that are locked underground.
♪♪ ♪♪ The baby chameleons delay hatching until the soil is soft enough to dig to the surface.
♪♪ ♪♪ ♪♪ ♪♪ After spending the dry season underground, the first thing they need is a drink.
♪♪ ♪♪ ♪♪ To begin with, butterflies and hawk moths are their equals.
It will be next season before a young chameleon is large enough to view them as food.
Until then, it's all a bit overwhelming.
Better just to close your eyes and pretend they are not there.
♪♪ The termites' contribution to the water hole community goes largely unseen.
But once a year, after heavy rainfall, the mound comes alive.
These winged termites are alates, which have developed underground and waited for rain.
♪♪ ♪♪ They will disperse over Tsavo to find mates and set up colonies of their own.
♪♪ [ Birds calling in distance ] For those at the water hole, they provide an annual feast.
[ Squawking ] The alates are rich in fat and protein.
They are high-energy food which is easy to digest.
A baby bullfrog still hasn't worked out which end to go for, but a wing is better than nothing.
The alate hatch lasts just minutes.
The water hole might last a century, going through seasonal cycles of feast and famine.
In time, it will silt up, each season there'll be less water, more grass, and eventually it will revert to bush.
♪♪ But as long as there are elephants roaming across Tsavo, one day a family will stop on the scar of an old termite mound.
♪♪ They'll walk away covered in mud.
♪♪ The hollow they leave will trap rain.
And in this land of termites and elephants, a water hole will be born once again.
♪♪ ♪♪ ♪♪ ♪♪ ♪♪ To learn more about what you've seen on this "Nature" program, visit pbs.org.