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Full EpisodeHummingbirds: Magic in the Air

Hummingbirds are the tiniest of birds, yet they are some of the toughest, most energetic creatures on the planet. Their unique flying abilities give them unmatched maneuverability, but at the cost of a supercharged metabolism that keeps them on the edge of survival. Hummingbirds spend most their lives in fast forward, but now high-speed video lets us enter their world.

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Narrator: HUMMINGBIRDS ARE THE SMALLEST BIRDS ON THE PLANET... BUT THEY HAVE POWERS AND ABILITIES FAR BEYOND THOSE OF OTHER BIRDS.

EVERYTHING ABOUT THEM IS AMAZING -- AND MYSTERIOUS... THE WAY THEY LOOK... THE WAY THEY FLY... THE WAY THEY'RE BUILT FOR SURVIVAL.

HUMMINGBIRDS LIVE THEIR LIVES IN FAST-FORWARD, INHABITING A REALM THAT'S LARGELY INVISIBLE TO US.

FINALLY WE HAVE THE TECHNOLOGY TO BREAK DOWN BARRIERS OF TIME AND SPACE... AND IT'S BECOMING CLEAR THAT HUMMINGBIRDS ARE EVEN MORE AMAZING THAN WE COULD HAVE GUESSED.

ENTER THE WORLD OF THE HUMMINGBIRD, WHERE THERE'S MAGIC IN THE AIR.

Narrator: THEY ARE THE MOST REMARKABLE THINGS ON TWO WINGS.

HUMMINGBIRDS ARE INTRIGUING... ENCHANTING... UTTERLY CAPTIVATING.

BUT THEY SELDOM PROVIDE US WITH MORE THAN A FLEETING GLIMPSE.

NOW, AT LAST, WE'RE ABLE TO SLOW THEM DOWN AND GET UP CLOSE.

AND AS WE EXPLORE THEIR UNIVERSE, WE DISCOVER SOMETHING NEW AT EVERY TURN.

HUMMINGBIRDS LIVE ONLY IN THE AMERICAS, BUT WITH NEARLY 350 DIFFERENT SPECIES, THEY ARE DAZZLING IN THEIR DIVERSITY.

THE SMALLEST OF ALL WARM-BLOODED CREATURES, THEY LIVE ON THE EDGE OF SURVIVAL.

BUT THEY ARE EQUIPPED BY NATURE TO MEET THE CHALLENGE.

PERHAPS THEIR GREATEST GIFT IS THEIR TALENT FOR FLIGHT.

JUST WATCH HOW THIS HUMMINGBIRD, A SPECIES CALLED 'THE MAGNIFICENT,' STANDS ITS GROUND WHILE IT FEEDS -- EVEN IF THE FLOWER IS BLOWING IN THE WIND.

WHAT IS THE SECRET OF THE HUMMINGBIRD'S AERIAL AGILITY?

BIOLOGIST DOUG ALTSHULER WAS INTRIGUED BY THAT QUESTION, AND HE DECIDED TO INVESTIGATE.

Altshuler: I HAVE TREMENDOUS RESPECT FOR HUMMINGBIRDS.

THEY REALLY ARE, I THINK, SOME OF THE MOST ELITE ATHLETES OF THE ANIMAL WORLD.

Abraham: HE HAS TURNED HIS LAB AT THE UNIVERSITY OF CALIFORNIA AT RIVERSIDE INTO A KIND OF HUMMINGBIRD TRAINING CENTER, WITH CUSTOM-DESIGNED WORKOUT STATIONS, WHERE HE CAN ASSESS THE LIMITS OF THEIR ABILITIES.

TO TEST THEIR COORDINATION, HE USES A REVOLVING FEEDER FILLED WITH NECTAR -- THE HUMMER'S FAVORITE FOOD.

MULTIPLE CAMERAS RECORD HOW THIS ANNA'S HUMMINGBIRD TWISTS AND TURNS, FINE-TUNING ITS POSITION SO IT CAN KEEP UP.

Altshuler: ONE OF THE THINGS WE'VE BEEN QUITE SURPRISED TO LEARN IS THAT IF WE LOOK AT ALL OF THESE BEHAVIORS, WE SEE THAT THERE'S ACTUALLY A VERY RESTRICTED SET OF SMALL TYPES OF MANEUVERS.

Abraham: FROM A LIMITED REPERTOIRE OF MOVES, THE HUMMINGBIRD CONSTRUCTS A DANCE OF INCREDIBLE GRACE AND PRECISION.

Altshuler: YOU COULD ALMOST THINK OF IT LIKE THE MOVES THAT A BALLERINA MAKES -- SHE MIGHT MAKE A PIROUETTE.

AND SHE MIGHT MAKE OTHER SPECIFIC MOVES.

AND, FROM THOSE, CONSTRUCT A MORE COMPLEX AND INTRICATE DANCE.

AND THAT'S REALLY WHAT WE SEE THAT THE HUMMINGBIRDS ARE DOING.

Abraham: THE CHOREOGRAPHY OF THESE TINY DANCERS REVOLVES AROUND ONE TALENT IN PARTICULAR -- THEY CAN HOVER.

THAT'S WHY HUMMINGBIRDS SEEM SO PERFECTLY BALANCED IN MID-AIR, AS IF THEY WERE FLOATING, RATHER THAN FLYING.

THEIR WINGS ARE UNLIKE THOSE OF ANY OTHER BIRDS.

WITH THEIR FLEXIBLE SHOULDERS THEY CAN EVEN MOVE THEM IN A FIGURE EIGHT -- AND THEY GAIN LIFT FROM BOTH SIDES.

Altshuler: HUMMINGBIRDS ARE QUITE IMPRESSIVE IN THE FLIGHT BEHAVIORS THAT THEY ENGAGE IN.

AND THIS INCLUDES MANEUVERING AND REALLY THE ABILITY TO DO SORT-OF UNUSUAL BEHAVIORS SUCH AS FLYING BACKWARDS, TURNING ON A DIME, AND EVEN BRIEFLY FLYING UPSIDE DOWN.

ALL OF THESE BEHAVIORS, REALLY, ARE RELATED TO THEIR ABILITY TO HOVER.

Abraham: THE HOVERING SKILL OF THE HUMMINGBIRD IS UNIQUE IN THE AVIAN WORLD.

ONLY INSECTS CAN FLY LIKE THAT.

THE HUMMINGBIRDS' ABILITY TO HOVER EVOLVED FOR A SIMPLE REASON -- IT ENABLES THEM TO DINE ON NECTAR.

SINCE MOST FLOWERS DON'T OFFER A PLACE TO PERCH, HOVERING IS THEIR ONLY ALTERNATIVE.

THIS UNUSUAL DIET HAS FORGED AN EVOLUTIONARY BOND BETWEEN HUMMINGBIRDS AND FLOWERS.

IN THE MOUNTAIN FORESTS OF ECUADOR, THERE LIVES A HUMMINGBIRD THAT GOES TO GREAT LENGTHS IN ORDER TO FEED.

THE SWORDBILL LIVES UP TO ITS NAME.

ITS 4-INCH BILL IS ACTUALLY LONGER THAN ITS BODY.

IT'S EASY TO SEE WHY... WHEN YOU LOOK AT THE FLOWER ON WHICH IT FEEDS.

THE TRUMPET-LIKE BLOSSOMS OF THE DATURA HANG STRAIGHT DOWN.

AND ITS NECTAR IS TUCKED AWAY AT THE VERY TOP.

BECAUSE THE NECTAR IS SO HARD TO REACH, ONLY THOSE WITH THE RIGHT EQUIPMENT CAN GAIN ACCESS.

OVER TIME, THE BLOSSOMS HAVE GROWN LONGER, AND SWORDBILLS HAVE EVOLVED TO KEEP UP.

THE DATURA HAS AN ULTERIOR MOTIVE -- IT'S BRIBING THE SWORDBILL TO GAIN ITS HELP IN REPRODUCTION.

AS THE BIRD FEEDS, IT'S DUSTED WITH POLLEN -- WHICH IT CARRIES TO THE NEXT BLOSSOM.

THE SWORDBILL HAS BECOME A DATURA SPECIALIST, AND THAT MAKES IT THE PERFECT POLLINATOR.

THIS MAY BE THE ULTIMATE IN 'FLOWER POWER' -- A PLANT REMAKING A BIRD TO DO ITS BIDDING.

THE DATURA IS FAR FROM UNIQUE.

SOME 8,000 PLANT SPECIES THROUGHOUT THE AMERICAS DEPEND ON HUMMINGBIRDS ALONE FOR POLLINATION.

THEIR WIDE RANGE OF FLOWER SHAPES HAS CO-EVOLVED WITH HUMMINGBIRD POLLINATORS TO PRODUCE AN INFINITE VARIETY OF LONG BILLS, SHORT BILLS, AND CURVED BILLS -- ALL DESIGNED TO FIT THEIR FAVORITE BLOSSOMS, LIKE A KEY IN A LOCK.

BUT CO-EVOLUTION ALONE CANNOT EXPLAIN THE BIZARRE CASE OF THE PURPLE-THROATED CARIB.

IT'S A MYSTERY THAT UNFOLDS ON THE TINY CARIBBEAN ISLAND OF DOMINICA.

LUSH RAIN FORESTS COVER THE MOUNTAINS OF THE ISLAND'S INTERIOR.

THEY'RE HOME TO SPECTACULAR FLOWERING PLANTS, AND TO HUMMINGBIRDS THAT HARVEST THEIR NECTAR.

THAT INCLUDES TWO HUMMERS WHOSE BILLS HAVE VERY DIFFERENT SHAPES.

AND HERE'S THE TWIST -- THESE TWO BIRDS BELONG TO THE SAME SPECIES.

THEY ARE BOTH PURPLE-THROATED CARIBS -- THE MALE ON THE LEFT, THE FEMALE ON THE RIGHT.

THE QUESTION IS, WHY DID THIS SPECIES END UP WITH SUCH DRAMATIC GENDER DIFFERENCES?

BIOLOGIST ETHAN TEMELES KNEW THAT THE BEST PLACE TO LOOK FOR THE ANSWER WAS IN THE FLOWERS.

MALE AND FEMALE CARIBS BOTH FEED ON HELICONIAS, WHICH HAVE VERY COMPLICATED BLOSSOMS HIDDEN WITHIN BIG MODIFIED LEAVES.

I'LL CUT THIS AWAY FOR YOU HERE.

YOU CAN SEE THE FRESH FLOWER PEEKING OUT RIGHT THERE.

THIS LITTLE THING, I'M LIFTING IT UP RIGHT HERE.

OKAY, THAT'S CALLED THE STAMINODE.

AND IT BLOCKS THE NECTAR CHAMBER.

SO WHEN THE BIRD FEEDS, IT ACTUALLY STICKS ITS BEAK IN ALL ALONG HERE, AND THEN ITS TONGUE WILL GO BACK INTO THE NECTAR CHAMBER AS IT FEEDS ON THE NECTAR.

Abraham: THERE ARE SEVERAL VARIETIES OF THE HELICONIA ON THIS ISLAND.

AND THE MALES AND FEMALES HAVE EVOLVED TO FEED ON DIFFERENT ONES.

Temeles: THIS IS A MALE PURPLE-THROATED CARIB.

THE BILL IS SHORT AND STRAIGHT.

THERE GOES HIS TONGUE.

A FEMALE BEAK IS ABOUT THAT MUCH LONGER, AND MUCH MORE CURVED.

Abraham: THE FEMALE FEEDS ON {end-italic} THE VARIETY CALLED WHOSE LONG, CURVED FLOWER PERFECTLY MATCHES HER BILL.

THE MALE PREFERS A DIFFERENT KIND -- NOT ONLY DOES ITS SHORT, STRAIGHT FLOWER HAVE THE RIGHT SHAPE FOR HIS BILL, IT'S ALSO EXTREMELY RICH IN NECTAR.

IN FACT, IT HAS ABOUT 50 TIMES MORE NECTAR THAN A TYPICAL HUMMINGBIRD FLOWER.

THE MALE CARIB IS BIGGER THAN THE FEMALE, SO HE HAS THE WILL AND THE MEANS TO DEFEND HIS TREASURE AGAINST ANY COMPETITORS.

TEMELES BELIEVES THAT WHEN THE ANCESTORS OF MODERN CARIBS FIRST COLONIZED THE ISLAND, THE AGGRESSIVE MALES STAKED OUT THE RICHEST FOOD SOURCE, AND NEVER LET IT GO.

Temeles: MALES CLAIMED THE MOST REWARDING HELICONIA, THE FEMALES WERE LEFT WITH THE LESS REWARDING, AND THEN OVER TIME THE BILLS OF THESE BIRDS EVOLVED AND ADAPTED TO THE TWO SPECIES OF HELICONIA.

Abraham: THIS ODD EVOLUTIONARY CHAIN OF EVENTS WAS PREDICTED BY NONE OTHER THAN CHARLES DARWIN.

BACK IN THE 1870s HE THEORIZED THAT SEPARATE FOOD SOURCES COULD PRODUCE DIFFERENT BILL SHAPES IN MALE AND FEMALE BIRDS.

IT TURNS OUT DARWIN WAS RIGHT -- AND THE CARIBS ARE LIVING PROOF.

ALTHOUGH HUMMINGBIRDS ARE BUILT TO FEED ON NECTAR, THEY CANNOT LIVE BY NECTAR ALONE.

IT DOESN'T PROVIDE ANY PROTEIN.

SO HOW DO THEY FILL OUT THEIR DIET?

SURPRISINGLY, THESE CREATURES THAT APPEAR SO DELICATE AND PEACEFUL ARE ACTUALLY AGGRESSIVE HUNTERS.

THEY PREY ON INSECTS, WHICH CAN MAKE UP MORE THAN A QUARTER OF THEIR DAILY DIET.

AND THEY COME BY THEIR TASTE FOR BUGS QUITE NATURALLY.

HUMMINGBIRDS ARE EVOLUTIONARY COUSINS OF SWIFTS -- SPEEDY LITTLE BIRDS WITH SHORT BILLS, WHICH LIVE MAINLY ON INSECTS.

AND, LIKE SWIFTS, HUMMINGBIRDS ARE EXPERTS AT AERIAL PREDATION.

BUT SCIENTISTS HAD NEVER REALLY FIGURED OUT HOW HUMMINGBIRDS -- WHOSE BILLS ARE DESIGNED TO FEED ON FLOWERS -- MANAGE TO CATCH INSECTS WITH SUCH DEADLY ACCURACY.

BIOLOGIST GREGOR YANEGA WAS IMPRESSED BY THE BIRDS' SKILL -- BUT STUDYING THEIR TECHNIQUE WOULD NOT BE EASY.

Yanega: IT'S HARD TO SEE.

THEY ARE VERY SMALL AND IT HAPPENS VERY FAST.

AND, FOR THAT REASON, WE REALLY DO NEED TO USE SOME SORT OF TECHNOLOGY, LIKE HIGH-SPEED VIDEO, TO GET A LOOK AT WHAT'S GOING ON.

Abraham: TO EXAMINE THEIR METHODS, YANEGA CONSTRUCTED A MORE CONFINED HUNTING GROUND.

IT'S BASICALLY A BIG FISH TANK STOCKED WITH A LOT OF FRUIT FLIES AND ONE HUNGRY ANNA'S HUMMINGBIRD.

YOU MIGHT EXPECT THAT THE HUMMER WOULD USE HIS LONG BILL LIKE TWEEZERS OR CHOPSTICKS TO SNATCH INSECTS OUT OF THE AIR.

THAT WOULD BE QUITE A FEAT.

Yanega: IF OUR LIPS AND JAWS COULD EXTEND IN FRONT OF US APPROXIMATELY FOUR FEET IN LENGTH, YOU KNOW, THEN IMAGINE TRYING TO, YOU KNOW, GRAB YOUR NEAREST ORANGE OR SOMETHING, WITH JAWS THAT ARE FOUR FEET LONG.

Abraham: SLOW MOTION REVEALS JUST HOW THE HUMMINGBIRD MAKES THE KILL.

OH, THAT'S A GOOD ONE!

Abraham: RATHER THAN USING THE TIPS OF HIS BILL LIKE CHOPSTICKS, THE HUMMER OPENS WIDE -- AND THE FLIES NEVER STAND A CHANCE.

Yanega: HE'S NOT GOING ALONG WITH THE CHOPSTICK MODEL OF, 'I'M GOING TO PICK EVERYTHING OFF WITH THIS LONG BEAK,' AND ONLY USE THE TIP OF THE BEAK.

HE'S USING, REALLY, THE BASE OF THE BEAK AND TRYING TO USE THE FATTEST PART OF HIS JAWS TO CATCH THE FLIES.

Abraham: THE HUMMER'S LOWER BILL CAN ACTUALLY BEND IN THE MIDDLE, TO SPREAD AN EXTRA 20 DEGREES, CONVERTING THOSE CHOPSTICKS INTO A CATCHER'S MITT.

Yanega: THROUGH THIS FLEXION OF THEIR JAWS, THEY ARE ABLE TO MAKE A REALLY LARGE CAPTURE SURFACE.

Abraham: WITH THAT BIG GULP, A HUMMINGBIRD MANAGES TO KEEP ITS LONG BILL OUT OF THE WAY.

AND THAT MAKES IT A LETHAL PREDATOR.

LESS LIKE 'TINKERBELL,' AND MORE LIKE 'JAWS.'

WHETHER THEY'RE FEEDING ON BUGS OR BLOSSOMS, HUMMINGBIRDS MUST CONSUME A LOT OF FOOD JUST TO MAKE IT THROUGH THE DAY.

ON AVERAGE, MORE THAN HALF THEIR BODY WEIGHT, IN NECTAR ALONE.

THAT MEANS VISITING MORE THAN A THOUSAND FLOWERS BETWEEN DAWN AND DUSK.

AND IT'S NO WONDER THEY EAT SO MUCH -- A HUMMINGBIRD'S METABOLISM IS STUCK IN OVERDRIVE.

EVEN AT REST, THE BIRD'S HEART RATE CAN BE UP TO 600 BEATS PER MINUTE.

[ HEART BEATING RAPIDLY ] AND THAT CAN DOUBLE WHEN IT'S FLYING.

[ HEART BEATING MORE RAPIDLY ] [ WINGS HUMMING ] AND THOSE TINY WINGS BEAT UP TO 200 TIMES EVERY SECOND.

IT'S AN ENDLESS CYCLE -- CONSTANT FEEDING GIVES HUMMERS THE ENERGY TO STAY ON THE MOVE.

BUT THEY BURN CALORIES AT SUCH A STEEP RATE, IT LEAVES THEM ONLY A NARROW MARGIN OF SURVIVAL.

TO FIND ENOUGH TO EAT, SOME HUMMINGBIRDS, LIKE THE WHITE-WHISKERED HERMIT, RANGE OVER A WIDE AREA, FEEDING ON ANY AVAILABLE FLOWERS.

OTHERS, LIKE THIS GREEN-CROWNED BRILLIANT, STAKE OUT A PATCH OF NECTAR-RICH FLOWERS AND DEFEND IT AT ALL COSTS.

HUMMINGBIRDS WON'T TOLERATE TRESPASSERS, AND THEIR AERIAL DOGFIGHTS ARE INTENSE.

FOR BOTH BIRDS, THE NECTAR IN THESE FLOWERS COULD BE THE DIFFERENCE BETWEEN LIFE AND DEATH.

BUT FINDING FOOD IS ONLY PART OF THE EQUATION.

CONSERVING ENERGY IS CRUCIAL, TOO.

AT NIGHT, WHEN A HUMMINGBIRD CAN'T FEED, IT FACES THE RISK OF SIMPLY RUNNING OUT OF FUEL AND PERISHING IN ITS SLEEP.

ONCE AGAIN, HUMMERS HAVE EVOLVED A WAY OF DEALING WITH THE PROBLEM.

WHEN DARKNESS FALLS, THE HUMMINGBIRD SETTLES ONTO A SAFE PERCH, AND IT FLUFFS UP ITS FEATHERS LIKE A DOWN COAT TO RETAIN BODY HEAT.

INFRARED VIDEO SHOWS WARMER AREAS AS RED, COOLER AS BLUE.

AS THE TEMPERATURE CONTINUES TO FALL, THE HUMMINGBIRD CONSERVES ENERGY BY ADJUSTING ITS THERMOSTAT, AND PRODUCING LESS HEAT.

IT ENTERS A LOW-ENERGY STATE CALLED 'TORPOR.'

IT'S LIKE GOING INTO HIBERNATION.

THE BIRD'S BODY TEMPERATURE, NORMALLY 105 DEGREES FAHRENHEIT, CAN DROP BY MORE THAN HALF.

IN INFRARED, THE HUMMINGBIRD IN TORPOR APPEARS AS COOL BLUE, LIKE THE AIR AROUND IT.

AND ITS HEART RATE SLOWS WAY DOWN -- TO AS LOW AS 36 BEATS PER MINUTE.

[ HEART BEATING SLOWLY ] THEN, WHEN THE AIR WARMS AT DAWN, THE BIRD SLOWLY EMERGES FROM TORPOR -- AND ITS VITAL SIGNS RAMP BACK UP TO NORMAL.

SOME HUMMINGBIRDS HAVE FOUND ANOTHER WAY TO SAVE ENERGY.

INSTEAD OF HOVERING TO FEED, THE ANDEAN HILLSTAR HOPS.

THE HILLSTAR LIVES ON THE HIGH VOLCANIC PLAINS OF SOUTH AMERICA, AT AN ALTITUDE OF 12,000 FEET.

THE THIN MOUNTAIN AIR MAKES IT MORE DIFFICULT TO FLY, LET ALONE HOVER.

FORTUNATELY, MOST OF THE FLOWERS HERE GROW CLOSE TO THE GROUND.

THIS MAY SEEM LIKE A STRANGE FORAGING TECHNIQUE FOR A HUMMINGBIRD.

HOPPING AND PERCHING CONSUME A LOT LESS ENERGY THAN HOVERING.

WITH THEIR AMAZING ADAPTATIONS, HUMMINGBIRDS CAN SURVIVE EXTREME CONDITIONS.

THE SURVIVAL OF A SPECIES, HOWEVER, INVOLVES A WHOLE OTHER SET OF SKILLS.

FOR HUMMINGBIRDS, AS FOR MANY OTHER CREATURES, SEX IS A GAME IN WHICH FEMALES MAKE THE RULES.

A FEMALE KNOWS EXACTLY WHAT SHE'S LOOKING FOR.

IT'S UP TO MALES TO MAKE A GOOD IMPRESSION.

[ CALLING ] SOME MALES LIKE TO ANNOUNCE THEIR PRESENCE WITH A SONG, LIKE THE INSISTENT CHIRPING OF THIS ECUADORIAN LONG-BILLED HERMIT.

THE LONG-TAILED SYLPH USES HIS FEATHERS TO WOO A MATE.

ONLY THE MALE SPORTS THAT EXTRAVAGANT ACCESSORY.

WHEN A MALE RUFOUS SPOTS A FEMALE IN HIS TERRITORY, HE LAUNCHES INTO A DANCE, BEST APPRECIATED IN SLOW MOTION.

WHILE HE SHUTTLES BACK AND FORTH, THE FEMALE PLAYS COY, HIDING IN THE FLOWERS.

BUT HE KNOWS RIGHT WHERE HIS AUDIENCE IS.

WHEN IT COMES TO HUMMINGBIRD MATING DISPLAYS, NOTHING CAN TOUCH THE ANNA'S.

MALE ANNA'S, WITH THEIR TRADEMARK FIERY RED CROWNS AND NECKS, PUT ON AN ELABORATE DISPLAY TO INTIMIDATE RIVALS AND ATTRACT A MATE.

THE MAIN EVENT IS A STEEP DIVE AT BREAKNECK SPEED -- ALMOST TOO FAST FOR THE HUMAN EYE.

[ BRIEF SQUEAK ] YOU MAY HAVE MISSED IT, BUT THE FEMALE CERTAINLY NOTICED.

HERE'S ANOTHER LOOK.

[ SQUEAK ] THERE'S ONE THING YOU CAN'T MISS -- EVERY DIVE IS PUNCTUATED BY A HIGH-PITCHED SQUEAK.

[ SQUEAK ] SO THIS IS THE TERRITORY I WAS TELLING YOU ABOUT... Abraham: BIOLOGIST CHRIS CLARKE IS INVESTIGATING THE ANNA'S MATING DISPLAY.

HE AND HIS ASSISTANT, TERESA FEO, HAVE BROUGHT SOME SPECIALIZED GEAR TO A PARK ON THE EDGE OF SAN FRANCISCO BAY.

Clarke: OKAY, IT'S RIGHT THERE.

Feo: OH, I SEE -- YEAH.

Clarke: THE FEMALE WILL GO AROUND TO SEVERAL MALES' TERRITORIES, AND THE MALE IS DOING THIS DISPLAY IN AN EFFORT TO IMPRESS HER, TO TRY AND CONVINCE A FEMALE TO MATE WITH HIM, RATHER THAN WITH THAT OTHER GUY OVER THERE.

Abraham: THE MALE'S DIVE IS HIS WAY OF FLAUNTING HIS PHYSICAL FITNESS, AND THAT UNUSUAL CHIRP IS A KIND OF SERENADE TO HELP WIN HER OVER.

BUT CHRIS IS CURIOUS TO KNOW HOW THE MALE MAKES THAT NOISE.

Clarke: THE SOUND SOUNDS VOCAL.

PEOPLE THINK THAT IT'S MADE VOCALLY, JUST LIKE THEIR SONG IS VOCAL.

BUT THERE'S ALSO A GROUP OF PEOPLE OUT THERE THAT THINK THAT IT MAY BE THE TAIL THAT MAKES THE SOUND.

BUT NOBODY HAS TESTED THIS IDEA BEFORE.

Abraham: CHRIS AND TERESA WILL USE A HIGH-SPEED VIDEO CAMERA TO RECORD THE DIVES AT 500 FRAMES PER SECOND.

A SENSITIVE MICROPHONE WILL CAPTURE THE CHIRPS.

THE REAL TRICK WILL BE GETTING THE MALE TO DIVE RIGHT IN FRONT OF CHRIS'S CAMERA.

Clarke: IT IS QUITE A CHALLENGE TO FILM THESE GUYS.

WHEN THEY'RE DIVING, THEY GO -- WE THINK AT ABOUT 60 MILES AN HOUR OR SO, AND, OF COURSE, THIS IS A LITTLE BIRD THAT'S ABOUT THIS BIG, WHIZZING BY AT THE SPEED OF FREEWAY TRAFFIC.

Abraham: CHRIS KNOWS THAT MALES TEND TO DIVE TOWARD THE SUN, TO SHOW OFF THEIR RED MARKINGS TO BEST ADVANTAGE, AND THAT HELPS HIM POSITION THE CAMERA.

HE'LL BE COMING FROM OVER HERE, SO RIGHT HERE WOULD BE A GOOD PLACE FOR THE CAMERA.

Abraham: TO PROVOKE THE MALE INTO PUTTING ON A DISPLAY, THEY PLACE A FEMALE INSIDE A MESH ENCLOSURE.

AND AS ADDED INSURANCE, ANOTHER FEMALE -- A STUFFED ONE -- IS MOUNTED ON A POLE.

Clarke: THIS IS A FEMALE THAT WE GOT FROM A WILDLIFE HOSPITAL.

SHE DIDN'T SURVIVE AFTER BEING ADMITTED.

Abraham: WITH THEIR GEAR IN PLACE AND READY TO ROLL, THERE'S NOTHING TO DO BUT WAIT FOR THE SHOW TO START.

AND IT DOESN'T TAKE LONG.

HE'S GOING UP FOR A DIVE!

THE MALE BEGINS HIS DISPLAY BY FLYING STRAIGHT UP ABOUT A HUNDRED FEET AND HOVERING TO ATTRACT ATTENTION.

THEN HE PLUNGES TOWARD THE GROUND IN A DEATH-DEFYING DIVE.

Clarke: DESCENDING! [ SQUEAK ] DIVE ONE... HE'S GOING UP.

[ SQUEAK ] THAT WAS DIVE 2.

GOING UP.

[ SQUEAK ] DIVE 3.

THAT WAS DIVE 3.

Clarke: ESTIMATES I HAVE FROM VIDEOS ARE THAT THE G-FORCES ARE ABOUT 10 G's... [ SQUEAK ] DIVE 7!

WHICH IS ABOUT THE SAME AS WHAT A PILOT BLACKS OUT UNDER IN FIGHTER AIRCRAFT. [ SQUEAK ] DIVE 14. DIVE 14.

Clarke: IT'S PHENOMENAL THAT THIS IS JUST A ROUTINE PART OF THEIR DISPLAYS THAT THEY DO.

DESCENDING -- DIVE 16. [ SQUEAK ] OKAY, HE'S BACK ON HIS PERCH.

YEAH, CHECK THIS OUT!

Abraham: NOW THAT THEY'VE RECORDED MORE THAN A DOZEN DIVES, THEY CAN TAKE A CLOSER LOOK -- IN SLOW MOTION.

SO RIGHT NOW YOU CAN SEE HE'S JUST OFF-SCREEN UP HERE, BUT HE'S GOING TO APPEAR AND HE'S GOING TO COME DOWN.

SEE THAT? HE SPREADS HIS TAIL!

YEAH, THAT'S REALLY COOL!

AND HE HAS HIS TAIL SPREAD FOR THE SAME AMOUNT OF TIME AS IT TAKES HIM TO MAKE THE SOUND.

[ DISTORTED SQUEAK ] Abraham: THE MALE IS SPREADING HIS TAIL FEATHERS RIGHT AT THE BOTTOM OF THE DIVE.

THE ACTION LASTS JUST 60 MILLISECONDS, BUT IT COINCIDES PRECISELY WITH THE MALE'S CHIRP.

WOW, THAT'S REALLY COOL.

Abraham: IS IT JUST A COINCIDENCE, OR ARE THE FEATHERS ACTUALLY PRODUCING THE SOUND?

[ SQUEAK ] CHRIS HAS DEVISED A SIMPLE BUT INGENIOUS WAY TO TEST THE THEORY.

Clarke: WE HAVE TUBES THAT HAVE AIR COMING THROUGH THEM, FROM AN AIR SOURCE.

WHEN WE PUT THE FEATHER HERE, WE PUT IT IN A JET OF AIR THAT'S MOVING 60 MILES AN HOUR.

[ WHISTLING ] Abraham: THE FEATHER MAKES A SOUND, VIBRATING LIKE A REED IN A CLARINET.

IT'S A DEAD MATCH FOR THE MALE ANNA'S CHIRP.

[ SQUEAK ] YEAH, RIGHT THERE.

THE EXPERIMENT PROVES THAT THE TAIL FEATHERS ARE MAKING THE SOUND.

SOMEHOW THE MALE IS ABLE TO DIVE AT JUST THE RIGHT ANGLE AND SPEED, SO HIS TAIL FEATHERS PRODUCE THE PRECISE FREQUENCY THAT THE FEMALE IS LOOKING FOR.

BY SHOWING OFF HIS FLYING SKILL HE LETS HER KNOW THAT HE'S A GOOD CHOICE FOR A MATE.

[ SQUEAK ] MALE HUMMINGBIRDS USE ANOTHER LURE TO ATTRACT A FEMALE -- IRIDESCENT FEATHERS.

LOOK AT THEM ONE WAY, AND THEY'RE DULL -- BLACK OR BROWN.

BUT WHEN THE LIGHT HITS THEM JUST RIGHT, THOSE FEATHERS SHIMMER.

AS USUAL IN THE BIRD WORLD, IT'S THE MALES THAT REALLY SHINE.

THEIR NAMES OFTEN REFLECT THEIR FLASHIEST ATTRIBUTE -- 'PURPLE-THROATED'... 'RUBY-THROATED'... 'FIRECROWNED'... SURPRISINGLY, A HUMMINGBIRD'S COLORS ARE NOT THE RESULT OF PIGMENTS.

INSTEAD, THEY'RE CREATED BY SPECIAL CELLS IN THE FEATHERS THAT BREAK DOWN LIGHT AND EMIT PARTICULAR WAVELENGTHS.

THOSE COLORS ENSURE THAT WHEN THE MALE HUMMER TURNS HIS HEAD, IT'S THE BEST WAY TO CATCH HER EYE.

WHATEVER TRICK HE USES TO MAKE HIMSELF ATTRACTIVE, IF A MALE IS PERSUASIVE ENOUGH, A FEMALE MIGHT DECIDE TO MATE WITH HIM.

BUT THE RELATIONSHIP WON'T LAST.

SHE'LL MAKE HER HOME AND RAISE HER YOUNG ALONE.

FEMALE HUMMINGBIRDS BUILD THEIR NESTS WITH SOFT BITS OF LEAVES, FEATHERS, OR LICHEN, OFTEN PASTED TOGETHER WITH SPIDER WEBS, TO MAKE THEM STRONG AND STRETCHY.

NESTS VARY ENORMOUSLY, DEPENDING ON THE SPECIES AND THE MATERIALS AVAILABLE.

IN THE DENSE LOWLAND FORESTS OF ECUADOR, THE BUFF-TAILED SICKLEBILL BUILDS HERS OVER A STREAM FOR DEFENSE AGAINST PREDATORS.

AND SHE ATTACHES IT TO THE UNDERSIDE OF A LEAF TO PROVIDE SHADE.

THE BRONZY INCA LIVES ON THE WESTERN SLOPES OF THE ANDES.

SHE USES LONG STRANDS OF MOSS TO BIND HER NEST TO A BRANCH.

A FEMALE USUALLY LAYS TWO TINY EGGS.

THE CHICKS EMERGE IN A COUPLE OF WEEKS.

[ CHIRPING ] THEY GROW FAST, ON A STEADY DIET OF REGURGITATED NECTAR AND INSECTS.

SOON, THEY'RE BIGGER THAN THEIR MOTHER.

AND THEY'LL KEEP ON GROWING UNTIL THEY'VE NEARLY OUTGROWN THE NEST.

EVEN AFTER THEY FLEDGE, THE CHICKS WILL STILL RELY ON THEIR MOTHER FOR A WHILE.

ONCE THEY'RE FINALLY FENDING FOR THEMSELVES, THEY'LL LOSE THOSE FLUFFY FEATHERS AND BURN OFF THEIR BABY FAT.

IN THE CHIRACAHUA MOUNTAINS OF SOUTHEASTERN ARIZONA, SOME HUMMINGBIRD MOMS HAVE COME UP WITH A UNIQUE STRATEGY FOR SUCCESSFUL NESTING.

BIOLOGIST HAROLD GREENEY IS AN EXPERT ON THE SUBJECT.

Greeney: SO WE JUST HAVE THIS SMALL DETOUR RIGHT HERE.

Abraham: HE HAS A TALENT FOR FINDING NESTS.

Greeney: AND IT'S RIGHT IN THERE ON THAT SECOND BRANCH.

SEE IT BACK THERE?

Abraham: THE FEMALE BLACK-CHINNED HUMMINGBIRD BUILDS HER WALNUT-SIZED NEST ON A HIGH TREE LIMB.

WE'LL CHECK IT OUT HERE.

Abraham: EVEN WAY UP HERE, HUMMINGBIRD NESTS ARE VULNERABLE -- OH, YES, STILL GOT EGGS.

SUBJECT TO ATTACK BY A HOST OF MARAUDERS.

HUMMINGBIRD EGGS ARE SO SMALL, THEY'RE LIKE LITTLE TIC TACS, THAT JUST ABOUT ANYBODY THAT FINDS THEM I THINK WOULD EAT THEM.

GREENEY AND HIS TEAM SPEND A LOT OF TIME MONITORING NESTS AND THEIR CONTENTS.

Greeney: I THINK THIS IS HATCHED TODAY.

Abraham: IT TAKES A VERY SENSITIVE SCALE TO WEIGH A BABY HUMMINGBIRD.

Greeney: SO, 0.401 GRAMS.

Abraham: THAT'S ABOUT THE WEIGHT OF A POST-IT NOTE.

THERE WE GO, BACK SAFE AND SOUND.

GREENEY RECENTLY DISCOVERED SOMETHING ASTONISHING ABOUT THESE BLACK-CHINNED NESTS.

IT APPEARS THEIR LOCATIONS ARE ANYTHING BUT RANDOM.

Greeney: WE WERE JUST OUT TO SEE WHAT WE COULD SEE AND LEARN A LITTLE BIT MORE ABOUT THEIR NESTING, AND WE NOTICED THAT THIS SPECIES OF HUMMINGBIRD OFTEN HAVE ALL THEIR NESTS CLUSTERED IN ONE PARTICULAR AREA.

Abraham: IT TURNS OUT THAT RIGHT IN THE MIDDLE OF EACH CLUSTER OF HUMMINGBIRD NESTS IS THE NEST OF ANOTHER KIND OF BIRD -- A COOPER'S HAWK.

COME ON OVER HERE.

THE COOPER'S HAWK JUST LANDED RIGHT NEXT TO THE NEST, AND HE'S OUT ON THE BRANCH.

Abraham: UNLIKE HUMMINGBIRDS, COOPER'S HAWKS EAT MEAT -- INCLUDING SQUIRRELS AND MANY KINDS OF BIRDS.

IN FACT, BIRDS ARE A COOPER'S HAWK SPECIALTY.

THE HAWKS CAN FLY WITH GREAT AGILITY THROUGH A THICK FOREST TO CATCH THEM ON THE WING.

STRANGELY, THE COOPER'S HAWK'S SKILLS AS A KILLER MAY BE EXACTLY WHY THE HUMMERS LIKE TO STAY CLOSE.

THE HAWKS' FAVORITE FOODS ARE ALL ANIMALS THAT PREY ON HUMMINGBIRD NESTS.

BUT THE HUMMINGBIRDS THEMSELVES ARE TOO SMALL AND FAST FOR THESE BIG RAPTORS TO BOTHER WITH.

SOMEHOW, THE BLACK-CHINS HAVE FIGURED OUT THAT HAWKS MAKE GOOD NEIGHBORS -- AND THAT SURVIVAL STRATEGY REALLY PAYS OFF.

SCIENTISTS LIKE HAROLD GREENEY AREN'T THE ONLY ONES KEEPING A CLOSE EYE ON HUMMINGBIRDS, OR MAKING SURPRISING NEW DISCOVERIES ABOUT THEM.

IN BATON ROUGE, LOUISIANA, A TEAM OF DETECTIVES IS SETTING UP A STAKEOUT.

THEY'RE LOOKING FOR A TINY CRITTER THAT'S NOT NATIVE TO THESE PARTS.

ONCE THEIR TRAP IS SET, THEY ONLY HAVE TO WATCH AND WAIT.

Woman: WE GOT ONE!

[ CHUCKLING ] Abraham: HEADING UP THE TEAM IS NANCY NEWFIELD.

SHE'S A LICENSED HUMMINGBIRD BANDER.

NANCY IS PART OF A NETWORK OF BANDERS ACROSS NORTH AMERICA, KEEPING TABS ON THE BIRDS' MOVEMENTS.

THIS IS A RUBY-THROAT.

THE LITTLE RUBY-THROAT WILL BE HELD CAPTIVE JUST LONG ENOUGH TO GET A PHYSICAL... 3.4 -- NICE WEIGHT.

AND HAVE A TINY NUMBERED BAND ATTACHED TO HER TINY LEG.

NEXT TIME SHE'S SPOTTED, THAT NUMBER, CHECKED AGAINST A CENTRAL DATABASE, WILL PROVIDE CLUES TO WHERE SHE'S TRAVELED.

YOU READY TO GO, SWEETHEART?

Abraham: THE RUBY-THROAT HAS A LONG TRIP AHEAD OF HER.

THERE WE GO.

Abraham: NEARLY ALL OF THE HUMMINGBIRDS FOUND IN THE U.S. AND CANADA ARE SEASONAL MIGRANTS -- BREEDING AND NESTING UP NORTH, BUT SPENDING THE WINTER IN THE TROPICS OF CENTRAL AMERICA.

TWICE A YEAR THEY MAKE A JOURNEY THAT IS TRULY EPIC.

GIVEN THEIR BODY LENGTH, HUMMINGBIRD MIGRATIONS ARE THE LONGEST OF ANY BIRD.

A RUFOUS MIGHT COVER UP TO 6,000 MILES ROUND TRIP, SHUTTLING BETWEEN ITS WINTER HOME IN CENTRAL MEXICO AND THE NORTHERN END OF ITS BREEDING RANGE IN SOUTHERN ALASKA.

A RUBY-THROAT'S MIGRATION BETWEEN PANAMA AND ITS SUMMER BREEDING GROUNDS IN THE EASTERN U.S.

IS NEARLY AS LONG.

THAT JOURNEY INCLUDES A MARATHON FLIGHT ACROSS THE GULF OF MEXICO.

IT'S AN 18-HOUR ORDEAL OVER 500 MILES OF OPEN WATER, WITH NO PLACE TO STOP, AND NOWHERE TO FEED UNTIL THEY REACH LAND.

BACK IN BATON ROUGE, NANCY NEWFIELD IS MAKING HOUSE CALLS.

I HEAR A CUSTOMER.

THIS IS AN ADULT MALE RUFOUS.

AND -- OH, HE'S A LOOKER.

Abraham: SOME OF THE BIRDS SHE CATCHES ARE ALREADY WEARING BANDS.

Newfield: 358 -- SO THAT'S TWO YEARS AGO.

Abraham: AND A FEW WERE EVEN BANDED RIGHT HERE ON PREVIOUS TRIPS.

I'VE HAD RUFOUS COME BACK FOR EIGHT YEARS, RUBYTHROATS, BLACK-CHINS, CALLIOPES FOR UP TO SIX.

Abraham: BANDERS HAVE DISCOVERED THAT HUMMINGBIRDS CAN LIVE AS LONG AS 12 YEARS -- A RIPE OLD AGE FOR SUCH A SMALL ANIMAL.

LET HER SIT IN YOUR HAND.

AND THE BIRDS FOLLOW THE SAME ROUTES YEAR AFTER YEAR, RETURNING TO THE VERY SAME GARDENS AND BREEDING GROUNDS.

[ BIRD CHIRPS, NEWFIELD LAUGHS ] [ BIRD CHIRPING ] Newfield: THIS IS A BANDED BIRD, A RETURNEE ADULT MALE RUFOUS.

3.9, SO HE'S GETTING A LITTLE PORKY.

HE'S PUTTING ON WEIGHT, GETTING READY TO LEAVE.

Abraham: TO SURVIVE THE RIGORS OF THEIR LONG MIGRATION -- HE'S GOT A FAT OF TWO.

HUMMERS GO ON AN EATING BINGE, AND STORE THE EXTRA FOOD AS FAT.

ZERO CORRUGATIONS.

THEY MAY DOUBLE THEIR WEIGHT BEFORE SETTING OUT, PUTTING ON THE EXTRA TWO OR THREE GRAMS TO SUSTAIN THEM ON THEIR JOURNEY.

FOR THE MIGRANT HUMMERS, THERE'S PLENTY TO EAT -- AS MORE AND MORE GARDENERS AND BACKYARD BIRDERS SET UP FEEDERS... AND PLANT NATIVE FLOWERS, WHICH TEND TO BE RICHER IN NECTAR.

LATELY, THERE ARE SOME SURPRISE GUESTS AT THIS BANQUET.

BANDING DATA REVEAL THAT MIGRATION PATTERNS ARE CHANGING.

IN THE LAST FEW DECADES, MORE HUMMINGBIRDS HAVE BEEN SHOWING UP ALONG THE EAST COAST DURING THE WINTER -- WHEN THEY'RE USUALLY FOUND IN MEXICO.

VAN REMSEN IS A BIOLOGY PROFESSOR AT LOUISIANA STATE UNIVERSITY.

Remsen: WHEN I FIRST GOT HERE, ANY HUMMINGBIRD IN BATON ROUGE WAS A BIG DEAL.

NOW, MOST PEOPLE WHO HAVE HUMMINGBIRD FEEDERS OUT HAVE TWO, THREE, FIVE, TEN.

IT'S A SPECTACULAR CHANGE FROM JUST THE LATE '70s.

Abraham: REMSEN BELIEVES THESE HUMMINGBIRDS ARE FIRST MIGRATING TO THE TROPICS AS USUAL, AND THEN VEERING NORTH AGAIN A FEW MONTHS LATER, TO THE GULF COAST.

NO ONE KNOWS EXACTLY WHY.

IT'S POSSIBLE THAT A GENETIC VARIATION ALTERED THE INTERNAL NAVIGATING SYSTEM IN A FEW BIRDS, CAUSING THEM TO CHANGE THEIR ROUTE.

SINCE THE NEW MIGRATION PATTERN IS REWARDED WITH FOOD, THE VARIATION IS PASSED ON TO NEW GENERATIONS.

Remsen: BUILT INTO HUMMINGBIRD BIOLOGY IS THIS ABILITY TO TRACK RESOURCES.

THEY CAN ADAPT TO NEW SITUATIONS.

I MEAN, THEY HAVE ADDED THE GULF COAST OF THE UNITED STATES TO THE WINTERING RANGE.

AND WE'RE NOT TALKING ABOUT JUST A FEW INDIVIDUALS -- THERE ARE PROBABLY HUNDREDS AND HUNDREDS, MAYBE SEVERAL THOUSAND HUMMINGBIRDS OF SEVERAL SPECIES THAT HAVE ADDED THIS PIECE OF REAL ESTATE TO THEIR WINTER RANGE, COME BACK YEAR AFTER YEAR.

VERY FLEXIBLE.

Abraham: THAT FLEXIBILITY IS A HUMMINGBIRD HALLMARK, AND A KEY TO THEIR SURVIVAL.

BUT TODAY, MANY OF THE NEARLY 350 SPECIES OF HUMMINGBIRDS ARE THREATENED OR ENDANGERED, AS THEY LOSE THEIR HABITATS AND FOOD SOURCES.

LUCKILY, THEY ARE FINDING CHAMPIONS -- IN SURPRISING PLACES.

A FEW YEARS AGO, A GROUP OF EUROPEAN BIRDERS JOURNEYED TO THE HIGHLAND FORESTS OF NORTHEASTERN PERU, HOPING FOR A GLIMPSE OF ONE OF THE WORLD'S RAREST HUMMINGBIRDS.

TO FIND IT, THEY ENLISTED THE HELP OF A LOCAL FARMER NAMED SANTOS MONTENEGRO.

[ MONTENEGRO SPEAKING SPANISH ] Abraham: GUIDED BY SANTOS, THE BIRDERS WERE ABLE TO WITNESS SOMETHING SEEN BY FEW OUTSIDERS, AND ONLY RECENTLY FILMED FOR THE FIRST TIME.

THE BIRD IS THE MARVELLOUS SPATULETAIL, AND IT IS TRULY A MARVEL.

THE MALE USES HIS TWO SPECIALLY MODIFIED TAIL FEATHERS IN AN EXTRAORDINARY DISPLAY.

TO IMPRESS A FEMALE, HE TWIRLS HIS FEATHERS, LIKE A COWBOY DOING ROPE TRICKS.

[ CLICKING AND BUZZING ] NO ONE HAS FIGURED OUT HOW HE MAKES THAT SOUND.

THERE ARE FEWER THAN A THOUSAND OF HIS KIND LEFT, AND MOST OF THEM ARE FOUND ON THE EASTERN SLOPES OF A SINGLE RIVER VALLEY IN PERU.

SURVIVAL IN THIS REGION IS DIFFICULT FOR HUMMINGBIRDS, AND FOR PEOPLE, TOO.

THE VILLAGERS MAKE THEIR LIVING BY GROWING SUGAR CANE ON THE HILLSIDES.

AS FARMING ENCROACHES ON THE MARVELLOUS SPATULETAIL'S HABITAT, THE BIRD IS FACING EXTINCTION.

SANTOS MONTENEGRO HAS BECOME THE MARVELLOUS SPATULETAIL'S AMBASSADOR -- AND ITS PROTECTOR.

[ MONTENEGRO SPEAKING SPANISH ] Abraham: SANTOS HAS PERSUADED MANY OF HIS NEIGHBORS THAT ECOTOURISM IS A MORE REWARDING USE OF THEIR LAND THAN FARMING.

THE SPATULETAIL RESERVE WAS ESTABLISHED TO SAVE A SINGLE SPECIES, BUT IT WILL ALSO PROTECT AN ENTIRE ECOSYSTEM.

SUCH IS THE HUMMINGBIRD'S POWER -- AND ITS POWERFUL HOLD UPON US.

WHEREVER HUMMINGBIRDS FLY... THERE HE GOES!

PEOPLE FLOCK TO SEE THEM.

AND IS IT ANY WONDER?

THESE LITTLE BIRDS HAVE CONQUERED THE AIR AND MASTERED THE ART OF SURVIVAL.

HUMMINGBIRDS ARE MORE THAN JUST BEAUTIFUL -- THEY ARE BRILLIANT.