NARRATOR: Nothing in the world is like a hummingbird.

Their abilities border on the magical.

Though they're the smallest birds in the world, they generate such speed, they appear to alter time.

Now with ingenious science and high-tech imagery, we're beginning to understand their deepest secrets.

Beneath their tiny, brilliant feathers, they are kung fu fighters, tender mothers, and some of the most dazzling aerial dancers in all the world.

You're about to enter the hummingbird dimension, where life moves faster and shines brighter on these super little birds.

NARRATOR: Hummingbirds seem to spring from the imagination.

Small and bright, they have abilities no other creatures possess.

Time seems to bend for them.

They float suspended or fly backwards.

Their wings beating faster than the eye can see.

They appear and depart with such speed, you're not sure you saw one at all.

Yet hummingbirds are made to be seen.

They catch the light.

A flash of emerald, a glint of sapphire, a blaze of ruby.

These sunlit jewels evoke such wonder, we struggle to describe them.

The tourmaline sunangel.

The sparkling violetear.

The long-tailed sylph.

The green-crowned woodnymph.

The wire-crested thorntail.

In real time, they're often long gone before we can say their names.

Almost everything about hummingbirds has been shaped by lifelong partners they can't do without -- flowers.

Hummingbirds are found only in the Americas, and all through their range, flowers have come to rely on them for an essential service.

They need a go-between to carry their pollen to another flower of their own kind so they can reproduce.

And so they dust a visiting hummingbird's forehead with pollen, and the bird flies from flower to flower, pollinating as it goes.

So close is their partnership, many blossoms have become a custom sleeve for hummingbird builds.

The flowers have gambled their future on the little birds.

Other pollinators who don't fly as far and as fast need not apply.

The hummer's reward is sweet, nutritious nectar -- their favorite food.

Nectar is the high-octane fuel that keeps them in the air.

But their fuel tanks are so small and their burn rate so high, a fill up only lasts them 20 minutes.

A hummingbird among flowers is on urgent business, zipping from bloom to bloom, seeking nectar before she runs out of fuel.

But no one had ever looked at what happens inside a flower when a hummingbird actually drinks until a young graduate student designed some ingenious flowers of his own.

HURME: Ooh, it's a mango.

RICO-GUEVARA: Nice.

NARRATOR: Alejandro Rico-Guevara and his wife, Kristina Hurme, met while they were PhD students at the University of Connecticut.

She's a behavioral ecologist, and he's an ornithologist.

RICO-GUEVARA: It's great.

NARRATOR: It's Alejandro's research into the form and function of hummingbirds that has brought them back to the mountains of his native Colombia.

RICO-GUEVARA: My passion is studying how animals look and relate that to what they actually do.

So, in the case of hummingbirds, we didn't know what they were doing inside the flower, and everything that makes a hummingbird what it is is feeding on flowers.

NARRATOR: To peer into a flower and see what's really going on, Alejandro needs a camera that can record at high speed and a most unusual flower.

RICO-GUEVARA: How's it looking for you?

HURME: It looks awesome.

NARRATOR: It's advertised with a flower sign hanging out in front that helps guide the hummingbird's bill to the nectar down in the tube.

RICO-GUEVARA: I can control how much nectar is in the chamber.

NARRATOR: And that chamber is made of glass slides to prevent distortion for the camera.

RICO-GUEVARA: We're all set there.

HURME: Hope it works.

NARRATOR: In no time, his flower has a customer -- a white-vented plumeleteer.

Instead of drinking through a straw-like structure, as many insects do, hummingbirds lap nectar up at an astonishing rate of 20 times a second.

Their tongues move almost as fast as their wings.

RICO-GUEVARA: Okay.

HURME: It's all set up on this side?

RICO-GUEVARA: Yeah.

NARRATOR: Alejandro's transparent flowers mimic not only the shape of actual nectar chambers, but also the amount of nectar the flowers contain.

The plants don't want the birds to linger.

Their aim is to keep the hummers on the move, seeking out more plants of the same species.

In just a second or so, a hummer has lapped up all the liquid the little chamber offers and moves on in a constant dance among the flowers.

But how is it possible for a tongue thinner than a fishing line to perform such a feat so fast?

Inside his workshop, Alejandro is creating something special.

He's mounting a real flower on to one of his clear feeding tubes with a cutout on the side -- a window to the inside of the flower.

Now with high-speed macro photography, we see something truly new.

Hummingbirds' long tongues have forked tips that open as the tongue dips into the nectar.

A fringe of tiny filaments uncurls along the edges of the open tips, creating grooves that spring open, filling the tongue with nectar.

It's a structure science has never seen before, and it's an incredibly efficient technology for picking up a liquid.

RICO-GUEVARA: He's right there.

NARRATOR: It was Alejandro's resourcefulness and the painstaking work he began as a grad student that has revealed something science had never imagined.

An unusual tongue is just the beginning of how flowers influence hummingbirds.

Feeding on flowers has shaped everything about the way they fly.

To sip on nectar, hummers have had to master the most challenging feat in the air -- hovering.

Hovering requires hummingbirds to beat their wings up to 80 times a second.

Like insects, hummers gain lift on both sides of a wing stroke, but their method is unique.

Handicapped by bones and feathers, they use their skeleton in a clever twist.

Even at 600 frames a second, it looks as though they flip their wings at the shoulder.

But their arm bones are so tiny compared to other birds.

Their wings are more like giant hands, able to rotate from a flexible wrist.

Back and forth, they scull the air as though treading water, hovering almost indefinitely.

They can stop or accelerate in an instant, lift straight up or down, and pivot in any direction a breeze takes a flower.

The search for nectar keeps them constantly in the air.

They live right at the edge of the energetic tradeoff between how much fuel they need to power their flight and the flight they need to find more fuel.

Living on such a tight budget, it's a marvel that their stronghold is here in the wild terrain of the Andes.

But hummingbirds' affinity for mountains is written in their genes.

Some 10 million years ago, as the Andes began to reach their rugged heights, they created many new worlds in which flowers and hummingbirds began to proliferate.

Today there are 338 species, and they are still evolving.

Yet how they keep their demanding metabolisms humming in the thin air at 16,000 feet has been a longstanding biological mystery.

WITT: It's a pretty good place to perch it if you want to control a piece of this valley here.

NARRATOR: Dr. Christopher Witt of the University of New Mexico has set up camp at a high valley in Peru.

He and his team risk altitude sickness at these heights, all to find out the hummingbird's secret.

WITT: Hummingbirds are just these spectacular metabolic machines.

When hummingbirds are hovering, they have the highest metabolic rates of any vertebrate.

How can they sustain such high metabolic rates when oxygen is so scarce?

40% more scarce than it is at sea level.

This is a fundamental paradox.

Why would these birds be so successful in these cold, rugged mountains?

NARRATOR: To find out, Chris has to catch some.

WITT: See these shrubs up here?

We've got tons of nectar, flowers.

NARRATOR: He sets up a couple of mist nets that will entangle the birds without hurting them.

WITT: There we go.

There's a couple birds moving there.

NARRATOR: It's not long before they have a catch.

WITT: Excellent. Looks like a black metaltail.

Beautiful. MAN: Yeah, yeah, we got it.

WITT: It's a sparkling violet here.

Looks like it's in great shape.

Looks like we got a shining sunbeam over here.

Beautiful.

That's why they call it a shining sunbeam.

It's a giant hummingbird.

This has got to be a big male.

It's 10 times the size of a calliope hummingbird right there. It's incredible.

NARRATOR: They've assembled quite a variety of high-mountain hummingbirds.

Now Chris' carefully designed test flights can begin.

WITT: I think it's just human nature to be interested in the limits of performance.

We want to know what's the most that a bird can do?

What's the extreme in terms of flight?

So, this is the sparkling violetear.

Right now, the bird is sort of figuring out the confines of its new chamber, but it's gonna spend most of its time on that brass perch.

NARRATOR: Oxygen forms about 21% of Earth's atmosphere.

Bit by bit, Chris will reduce the percentage of oxygen in the chamber to simulate an increase in altitude.

WITT: I'm gonna ratchet the oxygen down by infusing nitrogen.

So, we're at 13%. And the fact that it's hovering a lot is evidence that it's not having very much trouble.

I would say it's nowhere near its limit.

NARRATOR: Now the test gets harder.

WITT: There we go. 11%. NARRATOR: The violetear is asked to fly by temporarily removing her perch.

WITT: I'm so darn impressed with her athleticism.

It's now 7.5% oxygen.

She's having trouble.

That's an amazing feat right there.

Bird did an amazing job producing lift.

NARRATOR: It's not until the gauge drops to 6% that she truly reaches her limit.

That's an altitude equivalent of 43,000 feet -- well above the cruising limit of a jumbo jet.

But she still tries to fly.

WITT: That's incredible. I can't believe she can do that.

NARRATOR: Chris knew there had to be something special about hummingbird physiology to enable the violetear to perform so well with so little oxygen.

He discovered that a protein called hemoglobin, which we all have in our blood, has evolved in each hummingbird species to match its elevation.

For these hummers in the high Andes, they can grab scarce oxygen molecules like a magnet.

Now the giant sits in the chamber -- a true high-altitude specialist.

WITT: The current amount of oxygen, it's enough to send a human who's not acclimatized straight into a coma.

Perfect. Wow.

NARRATOR: The giant is finely tuned to thrive where oxygen is scarce.

Here in the high Andes, that gives it a strong advantage over other hummingbirds.

WITT: This is my favorite part.

We're gonna let this bird go back home.

Fly free.

Straight up slow. I love it.

NARRATOR: All the hummingbird species that live at high altitudes are just better at performing in thin air.

And remarkably, Chris and his team found that all hummingbirds have some degree of this amazing oxygen capacity.

WITT: Even in the lowland rainforest, many of the hummingbird species can easily withstand a reduction in oxygen that's equivalent to climbing to the peak of Everest, which is a shock to us.

That's a testament to how well designed their respiratory system is.

NARRATOR: Chris and his team have discovered a real hummingbird superpower, an ability to capture extra oxygen with every breath.

This is what makes it possible for hummingbirds to produce such dazzling speed.

And they need all that power, not just for feeding on flowers, but for fighting over them.

Flowers in full bloom are a call to arms.

It's fight and flight.

A display of skill and fiery tempers.

The bills they dip daintily into flowers, they now wield as weapons.

Gravity means nothing to them.

High-speed maneuvers are a show of force.

Wheeling, colliding, flying backwards.

Now they push themselves to the limit.

Hearts racing at 1,200 beats a minute, lungs bursting.

They spend every last molecule of oxygen, every ounce of fuel.

But at 500 frames per second, their battles are a breathtaking ballet.

Now and then, one stops at a flower for a sip of energy.

Or tries to.

10 gulps of nectar in half a second, and then back into the fray.

A long-tailed sylph sits on the sidelines.

His dazzling blue tail is at least as long as he is, but no help in a fight.

Flower after flower, he attracts the unwanted attentions of chestnut coronets.

At last, he gets the better of a little woodstar.

Then the coronets are back.

There's a brief moment of detente, aided by the flower's clever architecture.

But it doesn't last.

The sylph finally retreats.

The coronets all together are too much for him.

A tiny wire-crested thorntail is having a similar day.

But she's so small, she may be able to hide among the honeybees.

And just maybe the bees will let her have a sip of their flower.

As the day draws to an end, hummers face a dilemma.

They need to rest.

But even asleep, they'll burn too much energy to survive the night without constant refueling.

So they do the only thing they can -- they shut down and enter a state beyond sleep.

It's called torpor.

High in the Andes, a giant hummingbird sits motionless, snuggled deep into his feathers.

His usual high-speed metabolism slows by as much as 90%. His heart rate drops from 1,000 beats a minute to a mere 70.

His temperature falls from a feverish 104 to 46 degrees -- close to the ambient nighttime temperatures in these high mountains.

It's a state similar to hibernation, a winter he endures each night.

Far above, a vast universe sparkles and spins while hummingbirds everywhere brilliantly conserving energy wait for dawn.

It's a new day, and we're no longer in the jungle.

This is the Sonoran Desert, and even in the early morning, heat waves are rising.

Surely this is no place for a hummingbird.

But a pioneer has ventured here.

The flash of magenta reveals the little hummingbird to be a costa's, a desert specialist.

He's tough enough to handle the desert's arid conditions, and the Sonoran is rich in plants that flower all winter long.

Sitting high on a favorite perch, he scans the landscape for something special.

And there she is.

A female costa's.

Spring is the time to nest before the desert gets too hot.

Both birds are looking for a partner.

But the choice of mate will be hers.

It's up to him to impress her.

He moves in close, hovering directly in front of her, rocking his entire body back and forth in a display of flying prowess.

Though his back shimmers with green, it's not until we get her point of view that we see his true splendor.

He flexes the iridescent feathers of his mantle until they become a glowing mask of violet.

Facing into the blazing sun, he swoops back and forth, his face a fiery flower before her.

How can she possibly resist him?

And yet she does, leaving him to return to his perch.

Perfecting his performance is going to take some practice.

But what if he must woo a female in a dark, dense jungle, where just the right lighting is hard to come by?

The long-billed hermit has solved that problem with song.

And although they don't carry much of a tune, they can belt out quite a strong and distinctive chirp.

Marcelo Araya-Salas of Cornell University has spent seven years in the rainforest of Costa Rica studying the vocal stylings and mating rituals of the long bills.

As in many hermit species, the males form a chorus.

ARAYA-SALAS: You can actually hear one bird over there.

There's one bird here.

Two or three in this area.

NARRATOR: Marcelo is standing in the middle of a hermit lek.

A place where males come together to attract and compete for females.

This lek is a stage for 9 or 10 singers, and as small as they are, their voices carry across an area of some 300 by 450 feet.

It's not a free for all.

They listen carefully to each other and then chirp into the rhythm of the group, alternating their own calls with the others.

Although they're in competition, every voice gets its moment to be heard.

ARAYA-SALAS: You see those two birds?

It's a pretty active time because they're just coming back from breakfast.

They have breakfast around 6:15 to 7:00, then they come back pretty energetic, and they're singing a lot for two or three hours.

NARRATOR: Singing is just the beginning of the show.

Elaborate choreography comes next, and to see that, Marcelo sets up cameras.

He's recorded thousands of hours of intense hermit society.

The singers are all resident males.

They're mature and strong enough to hold a territory on the lek.

ARAYA-SALAS: Looks like some interaction right there.

NARRATOR: But instead of a female, the first to arrive is often a challenger, perhaps a young male looking to take over this spot.

A strange and beautiful duel begins.

It's ritualized combat conducted face to face.

The perch owner sees a challenger approach and starts a tail fan.

When the challenger alights, the resident begins a float display, hovering smoothly back and forth directly in front of him.

They take turns, each trying to outdo the other.

Sometimes they add a bill pop.

Flipping their heads up while making a popping sound.

And it all typically ends in a chase, the winner chasing the loser away.

All over the lek, performers compete for hours a day, some eight months out of the year, and it's all for this.

The moment when the intruder is not a challenger, but a female, and all the moves perfected by the contest with other males are performed for her.

In more than 2,000 hours of research video, this is the only mating Marcelo has recorded.

It's certainly one of the first hummingbird matings ever caught on camera.

After the brief encounters of the sexes, it's the females that take over the story, crafting one of the wonders of nature -- a hummingbird nest.

These two hermit chicks have spent their first three weeks of life at the tip of a leaf, protected from the rain by its wide green awning.

Now they are almost ready to fledge.

All their care and feeding have rested on their mother's tiny feathered shoulders.

But her first task of motherhood was to build them a remarkable home.

A rufous tail has begun her nest on the underside of a palm leaf.

Its spiny defenses are hummingbird-sized branches, perfect for her to weave around.

Her materials are fragile and light.

She can only use what she can carry on the wing.

Soft plant down is wrapped in long, green strands of lichen and other plant fibers.

Bits of leaves are tucked in.

Stretchy and strong, the nest takes shape around her.

As she builds the outside up, she tamps the inside down using her feet to shape a bowl.

She binds it all together with layers of sticky spider silk.

The project will take her five to seven days to complete.

When done, it's a perfect little cup, snug and warm.

It's finished just in time.

Before dawn, she settles in.

She's ready to lay her first egg.

It's an enormous effort for so small a body.

Her exertions are rewarded at last with one gleaming white egg.

She leaves it to dry and harden.

And returns the next morning to lay a second.

For the next two weeks, she will patiently sit, an iridescent flash in a rested motion.

She will feed and rest, feed and rest, building her strength for the job to come.

[ Thunder rumbles ] Rain is an almost daily occurrence in the tropics.

Hummingbirds don't seem to mind.

Neither rain nor thunder stays these little wings from their appointed flowers.

And they don't take bird baths.

They take showers.

When you're so small, a little water goes a long way.

This glittering-bellied emerald seems to enjoy a little splashing around.

A chance to shake things out and put them neatly back together.

But for hummingbird mothers, there's never a break.

Feeding themselves is a constant effort.

Now one hummer must support three.

And baby birds need more than nectar.

They need protein.

For that, hummingbirds go hunting.

Their prey, though almost too small to see, provide the extra boost all hummingbirds need.

They often emerge after a rain.

Tiny insects rising on the warming air.

Hunting takes practice and preparation.

A violetear makes sure her feathers are primed and ready to go.

She works from a perch with ample air space overhead -- a good hunting ground.

The first few runs are often misses.

Sometimes the catch is a nasty surprise.

But she tries and tries again, for inside every flower feeder, there lurks a bird of prey.

A good fly-catching perch is prime real estate.

Some indigo-capped hummingbirds attempt to move in.

And a brazen rufous-tail wants it for himself.

For hummingbirds, everything is a competition.

Above all, hummingbirds are restless and in perpetual motion.

At least twice in their very long history, their constant search for opportunity turn them north.

From deep in their South American stronghold, they cross the isthmus into Central America.

Then in a second wave of colonizing, they began to push across the border into the U.S.

and up into Canada.

Only 17 species have made it to North America, but they are resetting the boundaries of hummingbird country.

100 years ago, Anna's hummingbird spread only in Baja and southern California.

But in just a century, their breeding range has expanded north along the West Coast all the way to the Canadian border.

Today, some are permanent settlers, spending the winter as far north as the temperate rainforests of the Pacific Northwest.

Other hummingbirds migrate long distances each year, arriving from wintering grounds in Mexico and Central America to breed in the mountains of the American West just as their flowers bloom.

A female broad-tailed hummingbird has already started this year's family.

In her remarkable care, two little hummingbirds emerge into the world.

They are blind, almost naked, and utterly helpless.

Their mother begins their upbringing with a continuous supply of nectar and insects, the fuel that will power them through their entire high-speed lives.

Hatched a day apart, they don't look like much at the start.

But these homely, hungry little creatures have been born with astonishing gifts.

In just three weeks, they are transformed.

They barely fit in the next, which is already stretched to accommodate them.

Though growing fast, they still have their short baby beaks.

Content in their mother's care, they may have no thought of the wider world that awaits them, or that they will be able to fly.

A male broad-tail, his gorget rosy red in the sun, dips into flowers nearby -- a vision of the future.

Now they've discovered their wings.

They just need room to practice.

They're tapping into powerful new muscles they can't quite control.

But her little wings have come to the rescue.

Her recovery from near disaster has made her bold, and she flutters down the branch, away from the nest.

With one chick out, the second is soon to follow.

But they're not on their own just yet.

Their mother still provides for them with a demonstration of perfect flight control.

Then suddenly, they're gone with a flash of tiny wings.

They join these master works of nature, magic in the air, dazzling in the light.

Science and technology have struggled to catch up to them.

RICO-GUEVARA: How's it looking for you?

NARRATOR: Only now are we discovering the genius of their adaptations, the full extent of their powers.

And they're not done yet.

Hummers are still evolving, still becoming like no other birds on Earth.

The more we know, the more fascinating they are.

And so we will follow them the best we can as far and as fast as they fly.