Original subtitles

\h\h\h\h\h\h\h\h\h\hAfrica’s trees have stories to tell.

They can live for centuries

rooted in a breath-taking wilderness.

In the shadow of their mighty branches,

dramas unfold.

They nurture other life

from the smallest to the tallest.

They’re both home and hunting ground

and provide feast in times of famine.

They are the beating heart of a thriving ecosystem.

In Zambia’s Luangwa Valley, life depends on trees.

(MUSIC PLAYING)

It’s six months into Zambia’s dry season.

A grueling time for most animals,

unless you profit from death.

Hyenas will take their food dead or alive.

They can smell a carcass from over two miles away,

and stealing one is often easier than hunting.

This leopard loses over 20% of her kills to hyenas,

but she has a cunning plan to stash this one out of reach.

If only she has time.

Her enemies can’t climb.

She heads for the trees with her spoils.

(CHITTERING)

Providing her with both storage and security,

trees like this tamarind are her lifeline.

Up here she can rest easy.

She’s out of harm’s reach,

and has enough meat to keep her going for the day.

As with other animals in the Luangwa Valley,

she wouldn’t survive without trees to rely on.

Over 300 species of trees make up the valley’s woodlands.

Each one a habitat in its own right.

Together, they enrich an ecosystem covering 3,500 square miles.

They make South Luangwa National Park

a stronghold for 60 species of large mammals,

and over 400 species of birds.

Sausage trees stand emerald green in the parched landscape.

Famed for the gargantuan fruit that hang from their branches year-round,

they’re unique to Africa.

They’re a wonder tree.

Even when soil is sun-baked

and other plants have been trampled out of sight,

sausage trees sport luxuriant crowns over 65 feet wide.

Self-contained oases, they draw animals in.

It’s October.

At midday, the mercury hits 100 degrees Fahrenheit.

Lions find respite in the shade under a sausage tree,

saving their energy to hunt after sundown.

But in the canopy above them hides another predator that’s wide awake.

A male praying mantis.

His legs are the tools of his trade.

And as every assassin knows,

it’s important to keep your weapons clean.

He prepares for an ambush.

His huge compound eyes contain 10,000 light receptors called ommatidia.

Those on the outside scan for movement,

to help him detect prey,

while those in the middle provide clarity,

which he uses to lock onto a target.

(BUZZING)

He needs to be close to launch an attack.

Brilliantly camouflaged, patches of pigment in his forelimbs

match the delicate stripes on a sausage tree bud.

He moves with such stealth

that the bee has no idea it’s about to become a meal.

When the moment is right,

he strikes.

His spiny arms and powerful grip

keep the bee in place while he eats it alive.

Sausage trees aren’t just important hunting grounds for peculiar predators,

they’re also feeding grounds for extraordinary herbivores.

Giraffe are Earth’s tallest land animal.

Growing up to 16 feet tall,

they can reach succulent leaves

that are well out of reach of other ground-dwelling herbivores.

Giraffe gradually evolved from a deer-like ancestor 16 million years ago.

Necks became longer and longer over time,

and now account for almost half their height.

They consume almost 160 pounds of fresh foliage every day.

A modified joint in their neck

allows them to tilt their head vertically.

And just in case they need a bit of extra reach,

an 18-inch prehensile tongue

allows them to choose the choicest tips.

Their size allows them to exploit most of what the trees have to offer.

But size doesn’t matter, if you can climb.

Above the giraffe, hungry acrobats feed.

Sausage trees are popular hang-outs for vervet monkeys.

And this one’s more than just a salad bar.

Moth-eaten leaves betray the presence of caterpillars,

extra protein for industrious primates.

In return for an energy boost,

the vervets provide the tree with pest control.

Picking insect larvae from the leaves keeps the infestation in check,

and promotes healthy growth in the tree.

This arboreal maintenance will benefit the vervets down the line

by ensuring the tree bears fruit.

The trees in the Luangwa Valley

all have their own strategies

to survive the arduous dry season.

Groves of ebony trees are never found far from the river,

their long roots tapping into water

close to the surface.

But the most extraordinary adaptations

are where water is harder to find.

Cathedral-like groves of Mopane trees grow on poor, shallow soils

far from the river

where other trees can’t survive.

Every dry season, this remarkable mono-culture goes into lockdown.

To conserve water,

the trees cut off the supply of nutrients to their leaves.

Canopies turn golden, then brown.

And soon, butterfly-shaped foliage flutters to the ground.

A thick bed of leaves is just what this grey tree frog needs.

It will provide her with a protective blanket to hide under.

(CROAKING)

By slowing her metabolism,

she can survive for months without food and water.

But before she settles in, there’s one last job to do.

She smothers herself in her own waxy secretion

to help prevent moisture loss through her skin.

Mopane leaves are highly aromatic,

and fill the grove with an aroma similar to turpentine.

The biggest trees are almost two centuries old.

And with age comes character.

Cracked, hollow trunks attract one of the grove’s smallest inhabitants.

This strange protrusion

is the entrance tunnel to a nest of Mopane bees.

Just a eighth of an inch long,

these tiny stingless bees

mix Mopane tree resin with beeswax to build a home.

(BUZZING)

Safely inside the trunk are brood combs full of growing larvae.

(BUZZING)

Their elaborate entrance hole helps keep invaders out.

The ants below will make a meal out of the baby bees,

if they can get to them.

Sentries, stationed at the entrance,

raise an alarm with pheromones whenever danger looks imminent.

Worker bees scramble, eager to lay a trap.

A ring of fresh, sticky resin is gooey enough to stop ants in their tracks.

If push comes to shove,

they’ll even glue the ants’ mouths shut.

This time it’s a false alarm.

Foraging bees return with leg-loads of pollen to feed their hungry hive.

At the top of a Mopane tree, there are more nests.

They’ve all been built on the side of the tree most sheltered from the wind.

Each, is the bedchamber for a white-browed sparrow weaver.

These gregarious birds form tight-knit communities.

(CHIRPING)

Family groups forage together,

sifting the leaf litter for insects and seeds.

Any squabbles over food are quickly forgotten.

There are always more important building projects to be tended to.

Each bird has its own nest to roost in

and they must be maintained year-round.

Birds assist each other with DIY.

There’s no shortage of materials.

The exposed floor of the Mopane forest

provides an ample supply of dry grass.

The odd Mopane twig here and there adds a bit of rigidity.

These nests might look ramshackle,

but they’re well thought-out.

There’s even a second entrance hole

that can act as an emergency exit in the event of a snake attack.

Mopane trees harbor life,

even in the dry season when they’re in a state of dormancy.

Beyond the Mopane, farther still from the river,

forests become plains and, in the dry season, plains become dust.

Shallow-rooted plants lie dormant underground.

Rhizomes will only sprout new shoots when the rain returns.

The impala have little left to graze,

and must turn to browsing what leaves they can find.

It’s at the end of the dry season,

when things are looking desperate,

that giants awaken.

A Zambezi fig, one of several fig tree species in the valley.

It’s 60 feet tall,

with a 100-foot spread.

It needs to fruit before the rains return,

so that its seeds have a moist environment in which to germinate.

First, it must put all its energy into budding.

The fig tree’s transformation doesn’t go unnoticed.

Sweet, soft and easily digestible,

new buds are a treat for vervet monkeys.

The buds are packed with protein,

and their high-water content

means the monkeys don’t need to take

as many risky trips to the river to drink.

Like some human children,

young vervets are fussy eaters,

wasting nutritious outer leaves

to get to the succulent heart.

Luckily for the fig tree,

vervets rarely stay in one place too long.

Their foraging grounds extend across half a square mile

and they eat anything, from leaves to lizards.

Their adaptability saves any one tree from being ransacked.

When famine is still widespread,

nothing goes to waste in the Luangwa Valley.

Animals are on a quest to find nutrients anywhere they can.

Elephants trudge furthest of all.

Each adult female needs 300 pounds of food a day.

And mothers nursing calves require even more.

The riverine forest is a crucial resource.

Elephants assimilate only half of what they eat,

so they must shovel in as much as they can.

A utilitarian trunk allows adults to strip branches 20 feet up.

But until she’s tall enough, the little two-year-old is stuck with brittle twigs.

It’s time to move on.

A lilac-breasted roller follows,

hoping to profit from any invertebrates disturbed in the elephants’ wake.

The matriarch has a trick up her sleeve

to provide a feast for the whole family.

It’s time for operation "brute strength."

(CRASH)

With the entire tree down,

at last, even the young ones can enjoy

fresh, moisture-laden leaves.

It looks destructive, but in Luangwa,

elephants are always on the move,

saving any one tree line from total devastation.

At the tail end of the dry season,

sausage trees are preparing to reproduce.

Stalks known as peduncles,

sprout and dangle like exquisite chandeliers.

Each three-foot sprig bears up to 50 buds.

They don’t all open at once,

but in the hour leading up to dusk,

when the temperature and humidity are right,

the sausage tree starts to reveal its true glory.

Blood-red trumpets unfurl.

The flowers are an advertisement to pollinators everywhere.

"Food in exchange for fertilization."

(BUZZING)

Hidden inside each bloom is a pool of nectar that’s irresistible to bees.

A female bee will travel several miles looking for food.

Each time she visits a flower,

she carries a dusting of pollen

from another sausage tree with her,

fertilizing each plant she visits.

And where there are bees,

there are bee-eaters.

Every year, carmine bee-eaters from South Africa and Tanzania flock here to breed.

They tunnel six feet into the sand

to make a safe place to lay their eggs.

Each pair takes turns bringing food back for their partner on nest duty.

(CHIRPING)

They hunt on the wing, eating 500 insects a day between them.

That’s a lot of excursions,

but having a sausage tree nearby makes life a whole lot easier.

They perch among the flowering peduncles,

before setting off in pursuit of their target.

(CHIRPING)

Sharp eyesight allows them to track their quarry in flight.

Quick and agile, they can outmaneuver most insects.

The bee-eaters return to the colony

with the last of the day’s catch.

While they settle down to roost

near the sausage tree,

the creatures of the night are stirring.

At night, sausage tree flowers emit a musty odor

unpleasant to people,

but enticing to their most important pollinator,

nectar-loving bats.

But in the tree tonight, a different furry snout gets there first.

A genet has emerged from her woodland hidey-hole,

and what better way to fuel-up for a night’s hunting

than a slurp of sausage tree nectar?

A tail almost the same length as her body

helps her balance in the branches.

Like a bat, the pollen she carries on her fur

will fertilize other flowers if she visits another sausage tree tonight.

Genets are nimble tree-climbers,

but most of their foraging is done on the ground.

Despite a feline disposition,

a genet is more closely related to a mongoose than a cat.

Leopards do snack on them occasionally,

but they prefer something a little meatier.

And the woods are full of dozy antelope tonight.

The genet would relish a juicy mouse,

but grasshoppers, beetles and termites make up half of her diet.

At the sausage tree, other predators are out and about.

Bats.

But these ones aren’t interested in nectar.

There are 65 species of bat in Zambia,

of which 54 only eat insects.

These bats are bee hunting.

(BEES BUZZING)

Bees are busy round the clock,

collecting nectar and pollen for the hive.

They’ve nested in this neighboring ebony tree’s hollow trunk,

which may make the commute to work easy.

But with so many bees in one place,

it’s a boon for the bats.

Zeroing in on the bees using echolocation,

each bat can eat half its body weight in insects a night.

The genet uses more conventional means to home in on prey.

Her senses of hearing, smell and vision are all razor-sharp.

She’s spotted something.

A gecko would be a big meal for the genet.

But while she’s eyeing up her next meal,

other eyes have her on the menu.

A giant eagle owl weighs six pounds and stands over two feet tall.

It’s big enough to overpower a genet,

especially one that’s distracted.

This may be the genet’s last supper.

The owl seizes its chance.

Thick vegetation saves the genet.

While the leopard drags her fresh kill to cover,

the genet cleans up.

It’s been a good night’s hunting

for everyone in the woods tonight.

(HOOTING)

Well, almost everyone.

By the end of October, the height of the dry season,

sausage trees hold a special allure.

Antelope cruise in, starting at the break of dawn.

Others have been here all night.

This tree’s home to a family of five bush squirrels.

They spend the nights huddled up in a hole left by a rotting limb.

The best thing about living in a sausage tree

is that it comes with a juice bar.

No nectar-filled flower is out of reach.

Strong claws and ankle joints that swivel 180 degrees

allow the squirrels to dangle upside down.

Diving in nose first is sticky business.

But some squirrels have figured out a very shrewd workaround,

chewing a hole directly into the nectary at the base of the flower.

Africa’s smallest parrot has arrived.

Just five inches long,

Lillian’s lovebirds specialize on grass seed,

but their hooked beaks are perfect for ripping out stamens, too.

But this part of the flower isn’t to everyone’s taste.

Nectar is a mixture of complex sugars

that provides an important source of energy in lean times.

Monkeys have a hands-on approach to getting their fix.

The sausage tree will be pillaged as long as it produces flowers.

Once a flower has been fertilized,

its fruit will start to grow.

Each chandelier can only support one fruit,

so the other flowers on the stem become redundant.

Every day the tree drops the flowers that it no longer needs,

laying a crimson carpet on the ground.

Another gift to Luangwa’s animal inhabitants,

both small and large.

Across the valley,

it’s also time for the fig tree to share its bounty.

(ELEPHANT TRUMPETS)

It’s bursting with fruit.

These little green gems are a magnet to baboons.

There’s so much on offer here, they can afford to be choosy.

Any figs that aren’t perfectly ripe are rejected.

Vervet monkeys join in with fig quality control.

But a monkey’s trash is an elephant’s treasure.

So much so, that a 6,000-pound beast

will consume each juicy fruit, one at a time.

(ELEPHANT BELLOWS)

The figs are beginning to get the birds in a flap, too.

(BIRDS SQUAWKING)

A flock of Meves’s starlings is busy gorging.

An African green pigeon is a little more particular.

He’s a fig specialist,

and checks every one for ripeness.

He’s also got a possessive streak.

(BIRDS SQUAWKING)

Too big.

Too small.

An African grey hornbill seems to have just the right fruit,

but also a bill that could pierce a pigeon.

No point in risking a painful peck.

Sensibly, he waits.

(SQUAWKS)

Ah, just right.

The smell of fermenting fig wafts through the air

and stirs something in the leaf litter.

A corn cricket picks up the scent using his antennae.

He’ll eat almost anything, including carrion.

But the baboons’ leftover fig will do just as well.

Powerful mandibles, strong enough to draw blood from a human,

slice through fig pulp with ease.

Sensory palps are the equivalent of our tongue,

tasting his food.

After a sticky meal, it’s time for a wash.

If he’s to navigate the undergrowth,

it’s crucial to keep those all-important antennae clean.

As the sun sinks towards the horizon,

trees by the river become important bedrooms for baboons.

They roost in the treetops, the higher the better.

The promise of a safe treetop roost

brings other wanderers back from afar.

Red-billed quelea have spent the day

foraging for seeds on the parched plains.

(LOUD CHIRPING)

A quick bath washes dust from their plumage.

And so, to bed.

A single tree can host thousands of these birds.

Individually, they weigh less than an ounce.

But the combined weight of a flock

is more than a buffalo.

(CHIRPING)

It’s a crowded dormitory.

But, by huddling together,

they can dry off and keep warm overnight.

Little bodies have fast metabolisms.

By sharing their body heat,

each bird saves a lot of energy.

Most of the baboons have already nodded off.

Only the bravest stretch out.

Baboons typically sleep in a sitting position,

so they can spring into action.

Even up here, they’re not safe from predators.

Leopards are the only big cats

that can hunt baboons in their treetop roosts.

Tonight, this female is on patrol.

She must regularly delineate the boundaries of her territory.

Leopards are drawn to any large tree

with branches more than 10 feet from the ground.

They make the best hideouts.

Urine, infused with secretions from her anal glands,

leaves a clear message to any intruders.

"This tree is mine."

Whilst the leopard works to keep visitors away,

the fig tree actively attracts them.

Epauletted fruit bats disperse up to 95% of the figs’ seeds.

(BATS SCREECHING)

They navigate by vision and smell, rather than echolocation.

Fruit is usually consumed about 200 yards from the source,

to avoid attracting predators.

But some bats just get stuck in.

A single bat can consume 24 figs a night,

each containing 1,000 seeds.

To prevent the seeds from being destroyed by the bats’ digestive enzymes,

the figs encourage a swift passage through the gut.

They’re nature’s laxative.

By stimulating regular bowel movements,

the fig tree gets something in return from the bats.

Every night, the bats travel eight miles

between their foraging grounds and roosting trees,

pooping out seeds along the way.

A colony of just 100 bats

can disperse almost two and a half million fig seeds

in a single night.

As the flowering season draws to an end,

the sausage tree reveals another bounty for the animals.

The sausage-shaped fruits, which give the tree its name, begin to sprout.

Giraffe are the first to take advantage

of a new food high in the treetops.

But the sausages soon outgrow this onslaught.

Each one grows to over two feet long

and weighs more than 20 pounds.

The seeds inside are embedded in a tough fibrous matrix,

rather like a loofa.

When they’re this large,

a hard outer shell keeps most animals from eating the pods.

Like the fig tree,

the sausage tree relies on animals to help distribute its seeds,

but only a few have the teeth for the job.

When the fruit is ready,

it’s bombs away.

With canine teeth two inches long,

baboons can rip through the fibrous pulp to get at seeds inside.

The greatest guzzler of sausage fruit is the mammal with the biggest mouth.

With a bite force of 1,800 pounds per square inch,

three times the pressure required to crush a human skull,

a hippo can munch its way through them with ease.

A baboon abandons his fruit.

It’s not worth the pain of standing your ground for the sake of a sausage.

A female kudu arrives.

Kudu are Zambia’s second-largest antelope,

but she has a mouth more suited to nibbling leaves

than noshing sausage fruit.

It’s as though the hippo can’t bear to watch.

A kudu jawbreaker.

While the baboons taunt each other with their sausage spoils,

the kudu perseveres.

Finally.

(GULPS)

The sausage tree doesn’t make it easy,

but its fruit is tempting enough

to ensure that its seeds get spread far and wide across the valley.

Trees are by far Africa’s oldest living residents.

They’ve witnessed generations of animals come and go.

Every year, they endure the dry season,

providing food and shelter for the furred and feathered,

and a hunting ground for miniature predators and prey.

It’s a cycle that’s stood the test of time.

Like eternal sentinels,

trees protect and preserve the incredible diversity

in Zambia’s Luangwa Valley.

(MUSIC PLAYING)

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