It appears out of the dawn of time...
...a creation of the sun, caldron of life.
This is the tropical forest
nature at her most extravagant.
Sustained by the partnership of animal and plant,
it has produced more than half the species on earth.
It is a sea of green... seemingly spellbound... changeless.
But look again.
Behind the green curtain are countless battles for survival.
Into this complex world has come a rare breed of adventurer.
Scientific knowledge is the treasure they seek,
and to find it, they're not afraid to go out on a limb.
This is a place unlike any other in the world.
Panama's Barro Colorado Island,
known as BCI to the scientists who journey here.
A protected realm in the middle of the Panama Canal,
BCI is home to the Smithsonian's Tropical Research Institute.
Scientists come to this island from all over the globe
to unravel the mysteries of life in the tropical forest.
It is an adventure beyond
the reach of one person, or one lifetime.
BCI's a very special place for me just because the more I come here,
the more familiar I get with the island.
It's just home, it's comfortable, it's exciting.
I think Barro Colorado Island offers for me a lot of things
that I would not find in any other place.
It's a really highly diverse forest,
the research facilities are just fantastic,
you come there, you go out and do the work,
and Barro Colorado Island is protected
so that your work is not destroyed at all.
I discover things.
In the tropics you may be a person
who's discovered something
that not a single human being in the history
of the world has bothered to notice.
Here unfolds one of nature's great puzzles.
How does the tropical forest manage to support
such a remarkable community of life and sustain itself at the same time?
One thing is certain, at the heart of it all are the trees
A single tree, as it drives towards the light,
affects the lives of countless creatures.
But life is a struggle here for every creature
and the odds that any one seed
will grow into a Titan are astronomical.
It takes luck and strategy to make it to the top.
For people, getting to the top
always requires some special precautions.
Biologist Deedra McClearn has learned to seek
the forest's answers on its own terms.
Even if it means following her slingshot all the way up...
...into the crown of one of the forest's giants.
This is a dipteryx, one of the great ones.
It rises head and shoulders above the ocean of leaves around it,
more than a hundred feet tall.
From its majestic flowers will come fruit,
and from the fruit, perhaps an offspring
that will survive to take the place
of its parent among a procession of giants.
Climbing has taught Deedra to respect trees as individuals.
Since I've started climbing I like dipteryx,
because it's a beautiful tree, it's emergent,
it comes above all the rest of the trees,
they often have great views,
and the wood is really hard and solid.
I feel safe climbing a dipteryx,
chain saws won't cut down a dipteryx.
I have a lot of different emotions
associated with actually climbing a tree.
One of them is familiarity.
If it's a tree that I've climbed before,
I feel comfortable,
it's a very satisfying sort of feeling to make a good assent.
If it's a tree that
I haven't climbed before or it's given me troubles,
or I'm worried about a branch,
then it can be very nerve-racking.
Deedra climbs into the canopy to release a coati
a tropical cousin of the raccoon.
I know you.
She captures coatis just to let them go.
I have caught you 15 times and you always thrash around.
Just wait a second.
She's curious how an animal
who isn't a born climber manages to survive ten stories up.
I think coatis are really interesting
as climbing mammals because they're not perfect.
They're kind of clumsy, they're not graceful leapers,
they can't hang by their tail,
they don't have exclusively manipulative hands
to grasp onto branches,
but they do really well.
One of the things that really surprised me was that
they actually will jump quite a far distance going down.
It'll launch itself into a tree
and it doesn't really know where it's going to grab on,
it just, I think, assumes that
it'll be able to find something when it hits that...
The coati has a lot of company up here...
...with good reason.
The canopy is the forest's powerhouse.
This is where leaves transform
light into the stuff of life itself.
The canopy creates its own world,
with lands and waters, prey and predators.
It overflows with flowers, greenery, and fruit
food for all who can live at these heights.
Earthbound for years, scientists could
only guess what went on up here - until now.
The canopy is the last frontier on earth
and it's only been the last 10 or 15 years
that people have really gotten up into the trees
and started looking at the insects and looking at the leaves,
and actually there still hasn't
been that much mammal work up in the canopy,
but it's a different life zone.
It's like going to the bottom of the ocean.
You can't tell what's up here
from working on the ground and it's different.
Bold researchers like Deedra are proving how different
the tropical forest is from our preconceptions of the jungle.
For one thing, it is not always steamy and wet
Like many tropical forests, BCI has a long dry season.
Food is now becoming scarce.
Even coatis, who will eat just about anything
are hard pressed to fill their bellies.
They gather under the majestic dipteryx, waiting.
Now, when they need it most, the tree will bear its fruit.
For dipteryx this is the beginning of the long struggle to reproduce.
Howler monkeys gather in its crown.
Here is a banquet that will stave off hunger for many.
The timing is crucial. By fruiting during the dry season,
the dipteryx guarantees that many will gather for the feast.
Oddly enough, the tree wants its fruit to be eaten
even though each fruit contains a seed
that could bring forth the next generation.
But why?
All these capuchin monkeys know is that food is nearly at hand.
And if enough of them arrive,
they could drive the howlers from this nutritious meal.
What scientists have discovered
is the fruit is actually an expensive bribe.
If animals take it,
they may carry the seed locked inside far from the parent tree.
The further away the seed gets, the better its chance of surviving.
With ripening fruit all around them,
the canopy animals can now afford to be finicky eaters.
Once they've had the ripest bit,
they simply drop the fruit and move on to the next.
But this rain of half-eaten fruit
is of no help to the tree in its quest to reproduce.
Its seedlings have little luck of thriving here
in the shadow of the parent's crown.
Still for the animals waiting below, it's manna from heaven.
The coatis eat only the sweet flesh, they leave the seed intact.
But others are waiting in the wings.
Once the coatis have relieved their hunger,
agoutis gingerly join the feast.
Agoutis are rodents; they have teeth
and jaws designed to gnaw right
through the tough shell and devour the seed within.
Squirrels, too, relish the giant seeds.
Instead of creating new dipteryx trees,
the seeds simply feed a host of hungry visitors...
...even peccaries.
Satiated, the coatis settle into some mutual grooming.
In evening's golden light,
butterflies and ants gorge upon the remains of the feast.
It's been a good day for all the animals,
but bad for the lordly dipteryx.
Its potential offspring lie where they would have fallen away;
nothing has carried them away.
Has the tree's survival strategy failed?
Is the next generation lost?
Is there no help under the sun for the dipteryx?
Perhaps the moon can shed some light on the mystery of the dipteryx.
Tropical nights weave their own magic
and unveil a whole new cast of characters.
Everywhere, there are bats, conjured out of the dark.
Among the branches hunts a marsupial, a marmosa.
Its prey is pint-size, like itself...
...a katydid camouflaged unsuccessfully as a leaf.
Even while enjoying its meal,
the marmosa must be wary...
if it doesn't want to end up as dinner itself.
Dipteryx seeds make a nutritious meal for a spiny rat,
and a dangerous one as well.
Gnawing on the tough seed makes enough noise
to attract the unwelcome eye of a passing margay.
The tiny forest cat enjoys its meal,
until disturbed by yet another denizen of the dark.
Only at night does Elizabeth Kalko venture out on her own quest.
The Barro Colorado Island
she knows is very different from the one most people see.
The night is a totally different world from the daytime.
We are just exposed to a wonderful orchestra of different sounds,
of many insects and frogs,
then you see the stars through the canopy
and this is just an incredible atmosphere.
And occasionally there are bats fluttering by
and even touching you with their wings.
The night holds no fear for Elizabeth.
She is in her element, and bats are her passion.
She hangs nets of fine mesh over small streams, fishing for bats.
She believes bats are the unsung heroes of the night,
vital to the survival of dipteryx,
and many other tropical giants.
That's a short-tailed fruit bat,
and although they are relatively easy to get out of these nests,
one has to be very careful about their sharp teeth.
Bats rely on forest trees for food and shelter,
but they'll repay their hosts as they make their nightly rounds.
Legs are free, whoops, don't bite me, be nice, all right.
I don't think that bats are really ugly,
I think that the misconception
that bats are ugly comes from
our very limited knowledge about bats.
Most of the bats have very, very, very pretty faces
and especially here we find bats with beautiful facial stripes,
and colored ears,
and they actually have large eyes and don't look ugly at all.
But a bat is much more than just a pretty face.
Sometimes when I set mesh nets and bats fly in,
they bring a fruit with them and drop them in the mesh net
and so I can tell what kind of bat has taken what kind of fruit.
I know what this bat had for dinner.
Let's get it out of the mesh net here.
This is a fruit of the dipteryx.
And the bat has carried the fruit
in its mouth when it was hit into this net.
It turns out that the fate of our majestic dipteryx
rests upon the soft wings of a little bat.
Drawn by the scent of ripe fruit,
artibeus bats hover over the tree's canopy.
Yet death lies in wait among these boughs.
Luckily the bat's ability to "see" in the dark
using sound not only pinpoints the fruit,
it warns it of the hidden boa.
Another bat flies, locates fruit, carries fruit away
it tears it off the stem and carries it away.
Still it's far too dangerous to eat it here.
Only when it arrives at a safe roost,
usually tucked under the fronds of a palm tree,
does it stop to eat.
Unknowingly,
it has already performed a great service for our dipteryx.
The bat has carried the fruit away from the dipteryx,
beyond the reach of any diseases
or parasites that may plague the parent tree.
Once the bat gnaws off the sweet flesh,
it lets the seed drop.
Every night when the fruit is ripe,
artibeus bats make several visits to our tree.
And each time they return to the safety
of the same feeding roost to enjoy their meal.
After each trip,
another dipteryx seed joins the little mound forming just below.
Curiously enough,
in this heap of discards lies the tree's best hope for a successor.
Morning's light has scarcely revealed the half-eaten fruit,
when they are discovered by an agouti.
Have the precious seeds come this far, only to be wasted?
But the agouti can't possibly eat all that it has found.
And what it does next adds another piece to the puzzle
of how dipteryx manages to survive.
With the dry season continuing,
the agouti stashes the remaining seeds for the hard times to come.
Much like a squirrel buries a nut,
it carefully hides them, one by one.
Yet there will always be some it doesn't need or simply forgets.
Unwittingly,
the agouti has now planted the next generation of a tropical giant.
As the dry season on the island gets worse,
many canopy trees actually
shed their leaves in a tropical version of autumn.
For months, streams have been draining water away.
And torrid heat continues to rob the forest of precious moisture.
The remaining water collects in ever shrinking pools.
More and more trees drop their leaves;
it's a way to conserve water
and cut their losses as the drought deepens.
As always in the forest,
there's an animal that's found a way
to take advantage of every situation.
It hides among the fallen leaves disappearing in plain sight.
A caterpillar masquerading as a dead leaf.
But there's no hiding from the army ants.
Since many small creatures disappear in the dry season,
army ants are forced to tackle prey many times their own size.
They overwhelm them by sheer force of numbers.
Treehoppers suck the remaining sap out of plants.
But they're also under attack.
A mother defends her brood from a wasp trying
to steal one of her larvae for food.
Each time the larvae wave their legs
calling out an alarm,
the mother treehopper strikes back at the wasp.
By April, the dry season has turned cruel.
Famine is only just kept at bay.
The buds from the balsa tree are eaten before they can ever bloom.
The whole forest seems to hold its breath...
...waiting for the rains.
Over eight feet of rain may fall during the wet season.
The first good drenching triggers an avalanche of change.
This wet new world is paradise for creatures... water loving...
...and waterlogged.
Stan Rand, renowned frog man, is used to working in a deluge,
but it does have its drawbacks.
When you wear glasses such as I do,
you don't see properly because your glasses
get all wet from the rain on them
and then they get all steamed up inside and you can't see anything.
Luckily, sight is not the primary sense Stan uses in his work.
To truly enter the frog's world, he must wait until dark
and find his way through a landscape of sound.
What you hear are the voices of all these frogs
and on a good night there can be
14, 15, 17, different kinds of frogs
all calling at the same time,
all audible from the same place.
Only the males call, each in search of a mate.
To be heard and recognized
above all this amorous bedlam is a challenge,
challenging, too, for Stan and his students.
This is a young male pentadactylus like all frogs they eat live food,
frogs and mice and insects and probably small birds,
in fact, I know they eat small birds.
And he's got a dorsal secretion that is really quite nasty.
He got me. One of their defenses is this skin secretion...
Group walks away
For 30 years, Stan has lived in Panama not far from BCI.
He's become totally attuned to the ups and down of a frog's life.
He even understands why frogs use different calls at different times.
There's a physalaemus male.
You can tell he's calling by himself
because he's just giving a simple whine call... oow, oow.
If another male came in and began to call,
he'd change his call adding chucks to his call,
so he'd go, oow-chuck, oow-chuck- chuck.
I can sometimes get him to answer me as if I were another male...
See?
He went from going oow to oow-chuck,
oow-chuck, and now that I've stopped talking to him,
he's going back to the simple whines.
More frogs
Male frogs make the added "chuck" sound to attract females.
The females can tell from the pitch
which male is the biggest and strongest.
But male frogs have to think twice about sounding off.
Because females aren't the only ones
out there listening to the chucks;
predators are too.
So any male frog that wants to mate must gamble with his life.
And with other, bigger frogs nearby a call can be a fatal attraction.
But for those who survive long enough to mate,
it's a gamble well worth taking.
The male locks onto the female in a mating embrace.
As he fertilizes the eggs,
he whips the fluid released with the eggs
into a meringue-like nest of bubbles.
These tiny frogs mate in very shallow pools
at the foot of dipteryx and other trees.
The bubbles help keep the eggs moist and full of oxygen
and beyond the reach of aquatic predators.
Sometimes several pairs will
cooperate in creating a frothy nursery for their young.
Red-eyed tree frogs protect their brood differently.
They live high in the canopy,
more at home on dipteryx's spreading branches than in a pond.
They come down only when it's time to mate.
Then they must get their young close to water.
The males descend to the lower eaves of the tree,
where they call to the larger females.
After mounting the female, the male hangs on tight.
She's off on a search for just the right place to lay her eggs
a leaf overhanging a small forest pool.
Location is critical if it's too low,
her brood could be washed away by the next storm.
Sometimes the eggs are laid as high as 30 feet up.
The eggs are encased in a jelly-like mass
a gooey aquarium in which they'll develop into tiny tadpoles.
Only then will they drop into the pool below.
The young frogs rush to develop.
And none too soon.
A vine snake... three feet of elegant death.
In just four days the eggs have become recognizable tadpoles,
but they're not ready to take the plunge yet.
Even so, they may not have the luxury of waiting.
At this stage, the tadpoles can hatch.
But in just a few more days their tails will be much longer,
allowing them to swim better.
And once they're in the pond, they'll need to be good swimmers.
Fish will find the premature tadpoles easy pickings.
It's a deadly dilemma risk the snake's bite...
or leap into the waiting mouths of the fish below.
As if the fish weren't enough,
the tadpoles must contend with this monster in miniature.
A dragonfly nymph, a youngster itself,
is one of the fiercest creatures in this realm.
But there will always be some
who sidestep instant death and live to return to the trees.
Despite all appearances to the contrary,
even the dragonfly nymph will be transformed someday soon
and take to the tropical air.
Waking to a misty morning is an island wrapped in enchantment.
The rains have cast their spell.
And in the soil, the seeds of our dipteryx await a rebirth.
But before that can happen, the forest must change once more.
A carpet of forest litter, preserved in the dry air
now moisture melts it away.
In just a few days,
the nutrients locked away
in the dead leaves will be restored to the living.
Fungi and molds course over the withered remains.
Fungi are the middlemen,
mining the bodies of the dead
for riches which they supply to the living.
Here everything is recycled,
as a new generation rises from the moist earth.
The seedlings respond in rhythm,
spreading their leaves to catch the daylight,
folding them at dark.
Young vines grope for support.
They've traded strength for length,
and need help to climb towards the sky.
But wherever they grow,
they can't escape the hordes of hungry mouths that surround them.
To protect themselves from being eaten,
many tropical plants lace their foliage with poisons.
But these new leaves haven't
had the time to mount their chemical defense.
Yet in the tropics, poison to one is a treat for another
There's always some insect
that can find an antidote to a plant's toxins.
And from then on, it will be the only one they eat.
Leafcutter ants have found another strategy.
An army of workers seeks out only nontoxic plants
any and all they can find.
All herbivores are living recycling plants.
They absorb just a small fraction of what they eat.
The rest they return as manure
rich fertilizer that feeds the growth of the forest.
Unless if gets hijacked by a pair of industrious dung beetles.
A monkey dropping is a mother lode for the dung beetles,
who fashion it into a ball,
a combination pantry and nursery for their young.
They roll their stash away,
looking for a place to bury it among all the new growth.
A baby dipteryx enters this complex and competitive world.
It started life as a tiny flower in the canopy,
where it was pollinated and ripened into fruit.
It was carried away in the claws of a bat,
who ate its flesh, and discarded the seed.
It was buried alive by an agouti,
and has lain in wait for the rains for months.
Now, its time has come!
Only one in a thousand ever gets this far.
The huge seed stored enough energy to unfurl a giant among seedlings
nine inch tall, with lots of green.
Lots of juicy green.
But it is not a delicacy.
Not even a food of first choice.
But when other juicy edibles become scarce...
...baby dipteryx does end up on the menu.
The parent tree has spent centuries,
growing hundreds of feet and preparing millions of fruit,
so at least one offspring will survive to reach the canopy.
Yet all that effort can be gobbled up in seconds.
It will never survive being stripped bare.
And even those who remain intact need luck to prevail.
They must have light to live.
And light is hard to come by on the forest floor.
Each and every ray must penetrate
layers of foliage to reach a seedling below.
Animals can search out light,
but the seedlings, rooted in place, must wait for the sun.
They make do with sun specks that flicker over the forest floor,
illuminating them for just minutes each day.
Even if it gets its moment in the sun...
...the fall of a single leaf can seal a seedling's doom.
A new day in the forest sometimes brings disaster.
If a new tree is to thrive, another must fall.
For the plants that have struggled
to survive in its shadow, perhaps for decades,
this is a reprieve from a dark prison.
A light gap has been torn in the fabric of the canopy.
It has been centuries since this spot saw broad daylight.
For seedlings starved for the sun it is a chance to grow and flourish.
A race for the life-giving light has begun.
There will be winners and losers
as each plant tries to crowd out its neighbors.
Into the new light comes another creature,
biologist Phil Devries.
Phil studies the world of the light gap
and he's discovered some astonishing relationships here.
Since I've been a small child
I noticed plants and I noticed insects.
I like being in nature and I like forests a lot.
I can think of nothing more enjoyable
than being surrounded completely on all sides
and I literally mean up, down, any direction
with life and that's what being
in a tropical rain forest is all about.
His love for this forest world
is neatly matched to his quick eye and insatiable curiosity.
I observe as much as I possibly can,
and effectively what you're doing is you're asking,
"Hello organism, what are you doing for a living
and who do you interact with while you're out here doing your duties
as a butterfly or an ant or a lizard or a plant?"
I can use butterflies literally to move around in the forest
and tell me what the vegetation is like.
Phil has uncovered a light gap plant called a croton
that's developed an unexpected
relationship with two different insects,
an ant and a butterfly caterpillar.
Croton provides sugar secretions
which attracts ants to little nectaries,
and the ants when they're on the plant...
...deter herbivores, that is insects that eat leaves.
The plant actually uses ants to guard its vulnerable leaves
bribing them with a sugary nectar.
The ants keep away any insect that might do their meal ticket harm.
However, this is really what I'm looking for.
It's an herbivore as well,
but the ants don't bother it
because it produces sugar secretions of its own.
The butterfly caterpillar uses
its sugar secretions just as the plant does
as a tasty bribe.
It keeps the ants well-fed in exchange for their protection.
Back to ants & caterpillar
The funny thing about this butterfly caterpillar is that
it bribes these ants with a sugar secretion
and the ants act like guard dogs
and help protect it from it's own predators.
In addition to producing sugar secretions for the ants,
this caterpillar has another trick that's even more magic.
Phil has made another remarkable discovery.
These caterpillars can actually sing.
To capture this amazing talent Phil
has designed special audio equipment to record its calls.
This gear I have here is an amplifier and a very,
very sensitive microphone.
I use this to listen to well,
basically, sounds that nobody else can hear,
and I'm listening to this caterpillar singing at the moment.
And how these caterpillars produce
Their songs is pretty interesting in that on the top
of their head there are long bridges,
and right above the head
there's a collar where there are two little rods,
and the two rods beat up and down on top of the head,
and then the head moves in and out,
and these little rods have little rings in them,
and what they do is they hit the top of the head,
and then it's rasping back
and forth like a Latin American percussion instrument...
Caterpillar on mic, Phil's fingers move it to branch
I think it's fair to say, without gloating too much,
I have the world's largest collection of caterpillar calls.
Now let's see what happens
when we reintroduce this caterpillar to the ants.
Upon its return,
the caterpillar puts its musical ability to another surprising use
mimicking the calls of ants.
The ants respond as we would, if we heard a cry for help.
They rush over immediately. And help is always welcome.
Danger is never far away.
This guard ant earns its keep.
An assassin bug could skewer
the caterpillar and suck it dry.
But it's no match for the ant.
A parasitic wasp fares no better.
In the tropical forest,
every creature lives within an intricate web
shifting always between harmony and struggle.
The lesson that I've learned is
that it's probably just scratching the surface of the number
of interactions that you have in any light gap in the tropics.
The picture that emerges from there is of staggering complexity
when you think about how many species...
there are of plants in the tropics, and insects in the tropics.
It's very humbling to realize that,
even though I know a little bit
within the context of a tropical rain forest,
I know absolutely nothing.
This little dipteryx, of course,
also knows nothing of the complex network of relationships
that have brought it into the light.
So far, it has beaten the odds.
And if its luck holds out,
it may someday become a forest Titan itself.
Dipteryx, large and small,
is at the heart of a glorious pattern of forest life.
Unveiling this grand design remains the quest of the scientists
of Barro Colorado Island
a labor of love, and a journey of many lifetimes.
Perhaps centuries from now,
the forest will still be here and scientists will
still be working in its green depths
when our tiny seedling finally takes its place among the giants.