>> JUST TAKE A MOMENT AND LISTEN AND LOOK AT THEM.

[TRILLING, CHIRPING] >> Chang: TONIGHT, FOR THE FIRST TIME IN BROADCAST HISTORY, ONE OF THE WORLD'S LEADING BAT SCIENTISTS BRINGING US A LIVE LOOK FROM INSIDE THE CAVE OF THE LARGEST MIGRATORY BAT COLONY ON THE PLANET.

THEN TO VIRGINIA'S COASTAL MARSHES WHERE A CINEMATOGRAPHER IS HIDDEN INSIDE AN INGENIOUS BLIND, BRINGING US IMAGES OF MIGRATORY BIRDS LIKE YOU'VE NEVER SEEN BEFORE.

AND WE'LL TAKE TO THE AIR TO EXPERIENCE WHAT THOSE MIGRATIONS ARE REALLY LIKE, SOARING THROUGH THE SKIES.

PLUS, WE'LL BE TRACKING THE HEALTH OF SPRING'S PRETTIEST POLLINATORS ALONGSIDE CITIZEN SCIENTISTS LIKE YOU.

TONIGHT, TAKE A JOURNEY WITH US INTO THE SCIENCE BEHIND SPRING AS IT SWEEPS ACROSS AMERICA.

THIS IS "AMERICAN SPRING LIVE."

>> Chang: WELCOME TO "AMERICAN SPRING LIVE."

I'M JUJU CHANG COMING TO YOU LIVE FROM THE SIERRA NEVADA MOUNTAINS IN CALIFORNIA.

AND BEHIND ME YOU CAN SEE, NESTLED IN THOSE CLOUDS, SNOWCAPPED MOUNTAINS INSIDE SEQUOIA NATIONAL PARK, HOME OF THE GIANT SEQUOIAS.

IT'S DAY TWO OF OUR DEEP DIVE INTO SPRING, AND TONIGHT, IT'S ALL ABOUT MIGRATIONS.

AND JOINING ME AGAIN IS A GUY WHO'S ALWAYS ON THE MOVE, WORLD-RENOWNED BIOLOGIST, MY NEW FRIEND, DR. THOR HANSON.

AI HEY, THOR.

>> HEY, JUJU.

>> Chang: IT'S SO PICTURESQUE.

WORLD-RENOWNED BIOLOGIST >> IT IS, AND SEEING ALL THAT SUN NOW ON THE BIG GRANITE BEHIND US, YOU CAN EASILY UNDERSTAND WHY JOHN MUIR ALWAYS CALLED THE SIERRA NEVADA "THE RANGE OF LIGHT."

>> Chang: HOW POETIC, AND THERE IS A LOT OF GRANITE BACK THERE.

>> THERE IS A LOT OF GRANITE BACK THERE.

NOW, TONIGHT, WE WILL BE TALKING ABOUT SPRING AS A MOVABLE FEAST, MOVING FROM THE SOUTH TO THE NORTH AND FROM LOW ELEVATIONS UP TO HIGH ELEVATIONS, AND WE WILL LEARN ABOUT THE AMAZING ARRAY OF CREATURES THAT FOLLOW ALONG TO TAKE ADVANTAGE OF IT.

HIGH ELEVATIONS, AND W >> Chang: AND BIRDS ARE DEFINITELY TAKING ADVANTAGE.

THEY ARE MIGRATING AND FEASTING ALONG THE WAY, BUT THEY ARE NOT THE ONLY WINGED CREATURES DEFINIT MIGRATING NORTH WITH THE WARMER TEMPERATURES.

LET'S GO NOW TO TEXAS, JUST NORTH OF SAN ANTONIO, TO THE ATURES MIGRATING NORTH WI LARGEST BAT CAVE IN THE WORLD.

[BIRD SCREECHES] AND JOINING US LIVE FROM INSIDE THAT OMINOUS-LOOKING CAVERN, FROM BAT CONSERVATION INTERNATIONAL IS DR. WINIFRED FRICK, WEARING SOME SERIOUS PROTECTIVE GEAR.

DR. FRICK, CAN YOU EXPLAIN WHAT YOU'RE EXAMINING?

>> YEAH, I AM THRILLED...

I AM THRILLED TO BE STANDING IN THE MAIN CAVERN OF BRACKEN BAT CAVE HERE IN THE TEXAS HILL COUNTRY.

C THIS IS THE HOME TO THE WORLD'S LARGEST COLONY OF MEXICAN FREE-TAILED BATS.

NOW, THE BATS HAVE MIGRATED HERE ALL THE WAY FROM MEXICO, BY THE MILLIONS, AND RIGHT NOW, THERE ARE MILLIONS OF BATS DEEP BACK IN THE CAVE, COVERING THE WALLS AND WAITING FOR SUNSET.

IN A LITTLE WHILE, THEY'RE ALLS GOING TO FLY UP HERE AND BE SWIRLING ALL AROUND THIS CAVERN, GETTING READY TO HEAD OUT... OUT INTO THE NIGHT SKY.

THIS CAVERN IS 80 FEET HIGH, BUT WHAT YOU CAN'T SEE IS THAT I'M STANDING ON ABOUT 80 FEET OF GUANO, WHICH PUTS OUT A LOT OF FUMES, WHICH IS WHY I'M WEARING THIS MASK.

I LOVE STUDYING BATS, BUT SOMETIMES THEIR HOME ENVIRONMENTS CAN BE PRETTY INTENSE TO LOOK IN.

IT GETS EVEN MORE INTENSE THE FURTHER BACK IN THE CAVE I GO.

WITH ALL THE BATS, IT CAN GET OVER 100 DEGREES.

EARLIER, I WENT DEEP INTO THE FURTHER BACK IF THE CAVE I CAVE.

LET'S TAKE A LOOK.

[TRILLING, CHIRPING] >> WE'RE WAY BACK IN THIS CAVE, ABOUT 300 FEET, AMONGST L THOUSANDS AND THOUSANDS OF BATS.

IF YOU LOOK UP ON THIS WALL, YOU'LL SEE THEM.

THEY'RE ALL ABOVE US.

LOOK AT THAT!

THERE'S JUST THOUSANDS AND THOUSANDS OF THEM.

THEY'RE PACKED IN REALLY TIGHT.

THEY LIKE TO SNUGGLE REALLY CLOSE TOGETHER.

SOME OF THEM ARE FLYING AROUND.

YOU CAN HEAR THEM.

.

THEY LIKE TO SMU YOU CAN HEAR THEM CHIRPING.

THAT'S THEIR SOCIAL CALL.

THAT'S THEM TALKING TO THEMSELVES.

AND YOU CAN ALSO HEAR THEIR WINGS.

L. THAT'S THEM TALKING TO LISTEN FOR A SECOND.

[SQUEAKING] THAT'S THE SOUND OF THEIR WINGS MOVING, AND THE AIR... YOU CAN ACTUALLY FEEL THE AIR COMING OFF OF THEIR WINGS.

AND THEY'RE ALL COVERING ALMOST EVERY SURFACE IN THIS CAVE.

THAT'S THOUSANDS AND THOUSANDS THEY'RE ALL COVERING ALMOST EVERY SURFACE IN OF BATS COME HERE IN FEBRUARY.

THESE ARE ALL MOM BATS OR MOTHER BATS.

AND THEY'RE COMING HERE BECAUSE THERE'S LOTS OF GOOD INSECTS TO EAT, AND THEY'RE ALL GOING TO GIVE THEIR BABIES... HAVE THEIR BABIES IN JUNE, SO WE DON'T WANT TO DISTURB THEM TOO LONG.

SO WE'RE GOING TO GO OVER HERE AND PICK SOME DATA WHILE WE'RE IN THE CAVE, AND LET THESE MOM BATS BE, SO...

THE DATA WE NEED TO COLLECT IS A JUST A SMALL SWAB SAMPLE FROM THE CAVE WALL HERE.

AND WE NEED TO DO THAT 'CAUSE WE'RE LOOKING FOR THE FUNGUS THAT CAUSES THE DISEASE A WHITE-NOSE SYNDROME.

U WHITE-NOSE SYNDROME IS A TERRIBLE DISEASE THAT'S KILLED MILLIONS OF HIBERNATING BATS OVER THE LAST TEN YEARS IN NORTH AMERICA HERE.

NOW, WE DON'T HAVE THE DISEASE IN TEXAS, BUT THE FUNGUS HAS T HAVE THE DISEASE BEEN SHOWING UP IN CAVES, SO WE'RE GOING TO TAKE THIS SAMPLE BACK TO THE LAB AND HAVE IT TESTED TO SEE IF IT'S GOT THE FUNGUS SO WE CAN PROTECT THE BATS.

ALL RIGHT, LET'S MAKE OUR WAY TOWARDS THE ENTRANCE OF THE CAVE NOW.

[TRILLING, CHIRPING] IT LOOKS LIKE A MOONSCAPE IN HERE.

YOU CAN SEE THE GROUND.

THIS IS DECADES AND DECADES OF BAT POOP.

AND IF YOU LOOK UP CLOSELY, YOU CAN SEE THAT IT'S ACTUALLY COVERED IN THESE FLESH-EATING DERMESTID BEETLES.

AND LOOK AT THE GUANO.

IT'S REALLY CRUMBLY AND SOFT.

WHEN YOU WALK ACROSS IT, IT FEELS LIKE YOU'RE WALKING ON POWDERED SNOW, ALTHOUGH IT'S A LOT SMELLIER THAN SNOW.

THAT'S WHY WE'VE GOT THESE RESPIRATORS ON.

NOT ONLY DOES IT SMELL BAD, BUT THERE'S REALLY HIGH LEVELS OF AMMONIA.

;A SO, WE ACTUALLY NEED TO GO AHEAD AND GET OUT, AND WE'RE ABOUT TO SEE SOMETHING SPECTACULAR WHEN THESE BATS FLY OUT OF THE CAVE.

IT'S LIKE RIVERS OF BATS LEAVING THIS CAVE AND FLYING OUT INTO THE NIGHT SKY.

I JUST CAN'T WAIT TO SHARE IT WITH YOU GUYS.

SO, LET'S GO AHEAD AND GET OUT AND GO GET... WATCH FOR THEIR EMERGENCE.

AND GO >> Chang: AND DR. FRICK IS DESCRIBING 90-DEGREE HEAT AND NOXIOUS FUMES OF AMMONIA.

R. THAT'S LIKE HAZARD DUTY.

>> IT REALLY IS.

I'M IMPRESSED WITH HER DEDICATION.

I HAVE DONE A LOT OF BIOLOGICAL FIELD RESEARCH, BUT I'VE NEVER HAD TO WEAR A RESPIRATOR AND A HAZMAT SUIT.

>> Chang: AND CLEARLY SHE'S KEEPING CAUTIOUS.

FE NOW, WE ALL KNOW THAT BIRDS FLY SOUTH FOR THE WINTER AND RETURN IN SPRING, BUT WE DON'T ALWAYS APPRECIATE THE VAST DISTANCES THEY COVER, AND JUST LIKE ANY LONG-HAUL TRAVELER, THEY NEED REST STOPS.

THE VAST DISTANCES THEY COVER.

SO LET'S GO LIVE RIGHT NOW TO ONE OF THOSE STOPOVER POINTS IN VIRGINIA.

INTS AND THERE IN THE SHALLOW MARSHES VI OF VIRGINIA'S COASTAL WATERWAYS, WILDLIFE CINEMATOGRAPHER MICHAEL MALE CAPTURING STUNNING IMAGES FOR US OF BIRDS.

LI HE'S BUILT AN INGENIOUS BIRD BLIND.

MICHAEL, TELL US WHAT YOU'RE DOING.

[BIRDS SINGING] >> IT'S AN EXCITING TIME HERE ON IN THE EASTERN SHORE OF VIRGINIA.

UM, THIS MONTH AND ALL THE WAY UNTIL THE END OF MAY, THERE ARE, UM, JUST-- I DON'T KNOW-- IT'S PROBABLY...

IT'S... WELL, IT'S HUNDREDS OF THOUSANDS, I SUPPOSE, OF SHORE KNOW, PROBABLY HUNDREDS OF BIRDS THAT ARE ARRIVING.

THEY'RE, UM...

THEY'RE TRAVELING FROM WINTERING GROUNDS IN SOUTH AMERICA SOMETIMES, UM, SOME OF THEM, UH, THE CARIBBEAN, AND THEY'RE ON THEIR WAY TO THE BREEDING GROUNDS IN THE ARCTIC.

AND, UH, FOR ME, THIS IS A FABULOUS TIME TO, UH, TRY TO AND FOR ME THIS IS A FAB FILM THEM AS THEY-THEY FEED ON THESE MUDFLATS THAT ARE OUT HERE AT LOW TIDE.

RIGHT NOW, IT'S HIGH, SO, UM, THERE'S NOT MUCH HERE, AND NO I'M...

I'M WAITING FOR, UH, FOR LOW.

BUT, UM, DURING THE DAY, WHEN IT WAS LOWER, THERE WERE, UM, JUST A WHOLE RANGE OF SHORE T BIRDS OUT HERE FEEDING IN, UM, DIFFERENT...

DIFFERENT WAYS.

AND, UM, SOME OF THEM...

SOME OF THEM PROBE.

SOME OF THEM, UM... ME LET'S HAVE A LOOK AT WHAT-WHAT I, UH... WHAT I SAW EARLIER.

THEM... LET'S HAVE A LOOK AT WHAT I SAW EAR [BIRDS SINGING] >> IT'S REALLY AMAZING HOW MUCH FOOD THERE IS FOR THE BIRDS ON THESE MUDFLATS.

THERE'S ALL KINDS OF LITTLE INVERTEBRATES, AND, UM, THERE'S WORMS EVERYWHERE, AND THERE'S ND CRABS LIVING ALL THROUGH THERE.

THAT'S WHY THE MUDFLAT IS PACKED AT LOW TIDE WITH ALL THESE DIFFERENT SPECIES.

[BIRDS SINGING, SQUAWKING] >> THE NICE THING ABOUT BEING ABLE TO GET THIS CLOSE AND ACTUALLY JUST BE RIGHT IN THERE WITH THEM IS THAT YOU CAN FIGURE OUT THEIR STRATEGIES FOR-FOR FEEDING.

THIS GUY HERE IS A SEMIPALMATED PLOVER, AND THEY-THEY DO THIS...

THIS STOP-AND-START, UH, METHOD OF HUNTING.

AND THEY'RE CALLED "SEMIPALMATED" BECAUSE THEY HAVE, LIKE, WEBS IN BETWEEN THEIR TOES.

AND IT ALLOWS THEM TO GET LEVERAGE ON THE MUD, TO WALK ON THE MUD, AND TO-TO, UH, BE ABLE TO, LIKE THIS ONE, PULL THIS GIANT WORM-- WOW-- PULL THIS GIANT WORM OUT OF THE MUD.

HE HAS LEVERAGE TO DO IT.

[LAUGHS] [BIRDS SQUAWKING] >> THE PLOVERS-- THEY'RE HUNTING, UM, SORT OF INDIVIDUALLY, BUT OTHER BIRDS, LIKE YELLOWLEGS-- THEY SOMETIMES HUNT IN THESE LITTLE PACKS, AND, UH, THEY GO ALONG THE EDGE OF S THE WATER REALLY FAST, MOVING TH ALONG, SCARING STUFF UP.

AND-AND THE GROUP WORKING TOGETHER HELPS SCARE MORE FOOD UP SO THAT THE INDIVIDUALS S CAN-CAN, UH... CAN NAB IT.

ALL RIGHT, HERE'S A...

HERE'S A DOWITCHER.

AND THE DOWITCHER'S JUST DOING THE SEWING MACHINE MOTION.

I DON'T THINK THEY ACTUALLY SEE... SEE WHAT THEY'RE GETTING.

THEY-THEY ACTUALLY JUST POKE AROUND THE BOTTOM, AND-AND WHEN THEIR BILL, UM, ACTUALLY FEELS FOOD DOWN THERE, THEY-THEY SNAP ON IT AND-AND PULL IT OUT.

F IT'S REALLY FAST, AND IT'S HARD TO SEE WHAT THEY'RE GETTING, BUT IT LOOK LIKE THIS GUY IS GETTING THESE LITTLE RED WORMS THAT KIND OF CURL UP, UM, AND HE'S PRETTY RMS THAT KIND OF CURL UP, AN SUCCESSFUL AT IT.

THEY ALL DO WELL, BECAUSE THEY...

THEY FATTEN UP, UM, REALLY QUICKLY HERE AND-AND HEAD TO THE ARCTIC FROM HERE.

I >> Chang: OUR THANKS TO MICHAEL.

IT'S THE SECRET LIFE OF BIRDS.

SO AS THE TIDE CONTINUES TO GO OUT, WE'LL CONTINUE TO CHECK IN.

YOU KNOW, SO MANY OF US DREAM ABOUT WHAT IT'S LIKE TO FLY LIKE THOSE MIGRATORY BIRDS.

TONIGHT WE'RE GONNA GET CLOSE.

BIOLOGIST EMILY MISTICK IS ABOUT H TO SOAR ABOVE THE SIERRA NEVADA MOUNTAINS TO GIVE US A BIRD'S-EYE VIEW OF WHAT IT'S LIKE TO FLY.

>> MAN (over radio): SHE'LL BE LAUNCHING ANY MINUTE.

>> READY LAUNCHING.

>> CLEAR.

>> CLEAR.

>> HERE WE GO!

OKAY.

IT'S SPRINGTIME IN THE EASTERN SIERRAS.

I'M HERE AT 5,400 FEET OVER THE OWENS VALLEY, WHERE TENS OF THOUSANDS OF BIRDS MIGRATE THROUGH EVERY SPRING ON THEIR WAY NORTH LOOKING FOR FOOD AND NESTING GROUNDS.

THIS AREA IS SUPER IMPORTANT FOR MIGRATION, BECAUSE THERE'S GREAT HABITAT FOR FEEDING IN THE LAKES AND STREAMS, AND THERE ARE THESE HUGE MOUNTAINS FOR THE SOARING BIRDS TO TAKE ADVANTAGE OF THE THERMALS.

SO, THERE'S LOTS OF DIFFERENT KINDS OF BIRDS HERE.

WE'VE GOT SONGBIRDS AND RAPTORS AND WATERFOWL, RED-TAILED HAWKS OR MAYBE EVEN A RAVEN.

WE'RE OUT HERE DURING THE DAY, BUT THE MAJORITY OF BIRDS ACTUALLY MIGRATE AT NIGHT.

SMALL-WINGED SONGBIRDS, LIKE FINCHES AND SPARROWS MIGRATE AT NIGHTTIME, NAVIGATE BY THE STARS, BECAUSE THE WIND IS A LOT CALMER AND THEIR PREDATORS AREN'T OUT, AND THEN JUST AT FLY BY NIGHT AND NAVIGATE BY THE STARS BECAUSE THE WIND IS A LOT CALMER AN SUNRISE THEY FEED, EAT AS MUCH AS THEY CAN BEFORE TAKING SHELTER FOR THE DAY.

OH, COOL.

R THOSE MIGHT BE RED-TAILS.

LET'S SEE IF WE CAN GO CHASE THEM.

HERE'S A LITTLE THERMAL.

LET'S TRY TO STAY IN THAT.

SO, THERMALS ARE RISING BUBBLES OF AIR THAT ARE CREATED WHEN THE SUN HEATS THE EARTH, HEATS THE AIR AROUND IT, THAT COLLECTS UNTIL IT TRIGGERS AND RISES.

SOARING BIRDS MIGRATE DURING THE DAY TO TAKE ADVANTAGE OF THE THERMALS.

THEY RIDE THESE COLUMNS OF RISING AIR TO CONSERVE ENERGY, SO THEY DON'T HAVE TO FLAP, AND TRAVEL VAST DISTANCES.

THE PARAGLIDER IS A FABRIC AIR FOIL THAT ACTS THE SAME WAY.

WE CAN GLIDE, BUT WE CAN'T FLAP, SO WE LOOK FOR THERMALS TO TRY TO STAY UP, GO FOR OUR OWN LITTLE MIGRATIONS.

BIRDS JUST HAVE THIS REALLY INNATE SENSE OF WHERE THE THERMALS ARE GOING TO BE.

THEY'RE THE EXPERTS.

AND SO A REALLY GOOD INDICATOR OF WHERE THE LIFT WILL BE IS WHERE THE BIRDS ARE.

WHERE DID THAT PAIR GO?

OH!

THERE THEY ARE.

THEY'RE LOT HIGHER THAN I AM.

LOT HIGHER THAN I SO WE WEREN'T REALLY ABLE TO STAY IN THE THERMAL.

IT'S KIND OF EARLY IN THE DAY.

THE DAY IS JUST BUILDING.

THERE'S A LITTLE BIT OF WIND.

SO WE'RE GONNA FIND A PLACE TO LAND NOW.

>> TRY AND LAND TOWARDS... AT CODY, WALKING OUT.

>> OKAY.

THANKS, GUYS.

I'LL SEE YOU ON THE GROUND.

>> Chang: WHAT AN ADVENTURER AND A SCIENTIST ROLLED INTO ONE.

NOW, RECENTLY-- LOOK AT THAT.

>> YEAH.

>> Chang: IT'S AN ACORN WOODPECKER.

IT'S ONE OF OUR NEIGHBORS HERE AT SEQUOIA NATIONAL PARK.

>> IT REALLY IS.

AND THIS HAS TO BE ONE OF THE MOST PATIENT FAMILIES OF ACORN WOODPECKERS AROUND, BECAUSE THEY HAVE A NESTING HOLE IN A TREE RIGHT BEHIND OUR SET, AND THEY'RE JUST CARRYING ON AS NORMAL WITH A WHOLE TELEVISION SHOW PLAYING OUT ON THEIR DOORSTEP.

BE >> Chang: AND WHEN IT WAS SQUAWKING EARLIER, YOU SAID, "OH, THAT'S AN ACORN WOODPECKER."

NOW, I KNOW IT'S THE END OF APRIL, EARLY MAY, BUT THERE WK ARE STILL BIRDS MIGRATING ALL ACROSS NORTH AMERICA, RIGHT?

>> THAT'S RIGHT.

THEY ARE MIGRATING NOW.

LET'S TAKE A LOOK.

SO, THE GRAPHIC THAT YOU'RE LOOKING AT HERE SHOWS DOTS OF BIRD SPECIES MIGRATING OVERWHELMINGLY NORTHWARD.

AND WHEN THEY ARRIVE, THEY MAY NOT FIND EXACTLY WHAT THEY'RE EXPECTING, BECAUSE BIRD MIGRATION IS TRIGGERED BY THE LENGTH OF DAY, YET WHERE THEY'RE GOING, THE PLANTS AND THE INSECTS THEY EXPECT TO FIND ARE TRIGGERED BY TEMPERATURE, AND T WE KNOW THAT TEMPERATURE IS CHANGING RAPIDLY IN SPRINGTIME E WE KNOW WITH CLIMATE CHANGE.

SO THIS SETS UP THE OPPORTUNITY FOR WHAT SCIENTISTS CALL A TIMING MISMATCH.

>> Chang: RIGHT.

AND THAT COULD HAVE AM DOMINO EFFECT, AS WELL.

>> GREAT CONSEQUENCES FOR THE SPECIES INVOLVED.

>> Chang: RIGHT.

AND RIGHT NOW THERE ARE SONGBIRDS MIGRATING NORTH FROM SOUTH AND CENTRAL AMERICA.

CES FOR THE AND THEY'RE STOPPING, OF COURSE, FOR A REST BREAK IN TEXAS AT THE MAD ISLAND MARSH PRESERVE.

AND STANDING BY TO GREET ALL THESE ARRIVING MIGRATORY SONGBIRDS IS THE DIRECTOR OF THE Y SMITHSONIAN MIGRATORY BIRD CENTER, DR. PETER MARRA.

DR. MARRA, IT'S BEAUTIFUL THERE.

TELL US WHAT'S GOING ON.

>> Marra: WELL, JUJU, WE ARE IN THE MIDDLE OF A MAJOR MIGRATION.

IT'S A...

IT'S A REALLY EXCITING TIME HERE.

THIS IS ONE OF THE SPECIES THAT'S MIGRATING THROUGH.

THIS IS A COMMON YELLOWTHROAT.

IT IS A BEAUTIFUL BIRD.

IS LOOK AT THE BLACK FACE AND THE YELLOW THROAT AND THAT LIGHT EYEBROW.

DESPITE ITS SIZE, THIS LITTLE GUY IS AN ULTRA MARATHONER.

IT JUST COMPLETED A MAJOR, MAJOR FLIGHT, 14, 18, 20 HOURS NONSTOP, LARGELY AT NIGHT, ACROSS THE GULF OF MEXICO.

IT'S JUST INCREDIBLE.

AND EVERY SPRING WE SEE THIS SAME THING: BILLIONS OF MIGRATORY BIRDS THAT GO ACROSS THE GULF OF MEXICO TO BREED UP IN NORTH AMERICA AND THE U.S. AND CANADA.

WE CAUGHT THIS BIRD EARLIER.

I'M GONNA TURN THIS BIRD OVER TO DANIELLE TO BAND, AND I'M GOING TO GO SHOW YOU HOW WE CAUGHT IT.

WE'VE GOT THESE STRUNG UP ON POLES ALL OVER THIS BEAUTIFUL SCRUBBY HABITAT.

THESE ARE THE HABITATS THESE BIRDS THAT HAVE JUST MIGRATED ACROSS THE GULF OF MEXICO HIT, AND THEY WILL FLY THROUGH THESE AREAS TO FEED.

AND THEY'LL JUST HARMLESSLY HIT THE NET AND DROP INTO THIS POCKET.

AND WE'LL COME EVERY FIVE THE FEED.

MINUTES, TEN MINUTES, AND JUST SLOWLY TAKE THE BIRD OUT.

RIGHT HERE WE'VE GOT A BIRD.

IT'S AN INDIGO BUNTING THIS IS A... JUST AN INCREDIBLE BIRD.

LOOK AT THAT.

WOW, THAT BLUE IS NOT A BLUE THAT YOU SEE EVERY DAY.

IT JUST COMES OUT HARMLESSLY OUT OF THE NET.

IT'S A SOFT NYLON NET.

BUT LOOK AT THAT.

THAT'S AN OLDER MALE.

N LET'S PUT IT IN THE BAG AND KEEP GOING.

ONE OF THE CHALLENGING THINGS THAT WE HAVE TO DEAL WITH AS MIGRATORY BIRD BIOLOGISTS IS THAT THESE BIRDS ARE SO SMALL, WE HAVE A REALLY HARD TIME TRACKING THEM AS THEY MOVE ACROSS THE CONTINENT.

SO OVER JUST THE LAST FEW YEARS, THERE HAVE BEEN SEVERAL MINIATURIZED TRACKING DEVICES THAT HAVE EMERGED THAT HAVE ALLOWED US TO FIGURE OUT WHERE THESE INDIVIDUAL BIRDS GO AS THEY MOVE FROM CENTRAL AMERICA INTO THE U.S. AND UP INTO CANADA.

THE TAG WE'RE GOING TO PUT ON THIS BIRD RIGHT HERE IS CALLED A NANOTAG.

AND WHAT'S REALLY COOL ABOUT THIS IS IT'S SO SMALL.

AND ACROSS THE UNITED STATES AND CANADA, PEOPLE HAVE BEEN PUTTING UP ANTENNAS EVEN IN THEIR SM BACKYARDS.

SO THERE ARE HUNDREDS AND HUNDREDS OF THESE ANTENNAS ALL I OVER THE PLACE, SO WHEN THIS BIRD ACTUALLY FLIES...

IT FLIES BY AN ANTENNA, IT'LL ACTUALLY PING THAT ANTENNA AND WE CAN ACTUALLY KEEP TRACK OF WHERE IT'S GOING.

IT'S ONLY IN THE LAST FEW YEARS THAT WE'VE BEEN ABLE TO DO THAT.

SO...

THE TECHNOLOGY'S EMERGING REALLY RAPIDLY.

IT'S QUITE AMAZING.

G. DANIELLE, YOU'RE READY TO, UH, CROCHET HOOK THIS BIRD ON?

THIS T...

THIS TAG IS REALLY SMALL, SO THE BIRD WON'T EVEN KNOW... THAT IT'S ON.

>> Marra: SO, THIS BIRD IS GONNA.... THIS-THIS ANTENNA... A AND THIS TAG WILL ACTUALLY PING THESE... PING THESE ANTENNAS, AND WE'LL BE ABLE TO TRACK THIS BIRD.

SO WE'LL KNOW THAT THIS SE BIRD LEAVES HERE AND POTENTIALLY FLIES THROUGH MISSOURI OR FLIES THROUGH CONNECTICUT.

S THESE ARE THE SORTS OF THINGS THAT WE JUST... HAVE BEEN MYSTERIES ABOUT THE MIGRATION OF THESE BIRDS FOR YEARS AND YEARS.

AND IT'S ONLY RECENTLY THAT WE'VE BEEN ABLE TO DISCOVER THESE THINGS.

YOU CAN SEE THAT TAG RIGHT THERE.

SO, WE'LL LET THIS BIRD HEAD OFF ON ITS WAY, AND HOPEFULLY, WE'LL HEAR FROM IT SOMEWHERE ELSE.

AR >> Chang: FLY AWAY, LITTLE BIRDIE.

AND HERE IN THE SEQUOIA NATIONAL PARK, THAT'S, I'VE COME TO LEARN, SOMETHING CALLED A PIKA.

>> YES, IT'S A LITTLE PICA.

THIS IS AN ANIMAL THAT LOOKS A SO LOT LIKE A RODENT, BUT IS ACTUALLY MORE CLOSELY RELATED TO A RABBIT.

AND IT'S SMALL, JUST THE SIZE OF A SOFTBALL OR SO.

AND IT'S ALSO A CREATURE THAT IS SUFFERING FROM CLIMATE CHANGE, IN THAT IT LIVES AT VERY HIGH ELEVATIONS.

AND WHEN THE CLIMATE WARMS, IT HAS VERY LITTLE HABITAT TO RETREAT TO.

>> Chang: IT DOES LOOK LIKE A GIANT HAMSTER.

BUT EARLIER, THOR, YOU WERE TALKING ABOUT HOW SPRING MOVES, AND OFTEN SCIENTISTS.

DESCRIBE THAT MOVEMENT AS VERY LIT COMING IN WAVES.

>> THAT'S RIGHT.

WE OFTEN REFER TO IT AS THE GREEN WAVE.

AS TEMPERATURES WARM FROM SOUTH TO NORTH, THE PLANTS RESPOND.

THE SEEDS SPROUT AND GRASSES GROW AND TREES AND SHRUBS LEAF OUT.

AND THAT TRIGGERS A WAVE OF ACTIVITY IN THE INSECTS AND IN THE THINGS THAT EAT THE INSECTS, IT THE WHOLE FOOD CHAIN STARTS TO RESPOND.

AND, OF COURSE, MIGRATORY ST SPECIES MOVE BEHIND THAT WAVE, TRYING TO CATCH UP WITH IT AND TAKE ADVANTAGE OF ALL THE OPPORTUNITIES IT HAS TO OFFER.

>> Chang: OF COURSE, THE PREDATORS WILL FOLLOW, TOO, AND ON THE MOVE RIGHT NOW FOLLOWING THIS GREEN WAVE ARE THE MULE DEER.

AND TO GET A SENSE OF THE CHALLENGES THEY FACE, LET'S HEAD NOW OVER TO IDAHO AND THE BOISE MOUNTAINS.

BIOLOGIST HOLLIE MIYASAKI HAS SPENT YEARS TRACKING THESE EXTRAORDINARILY SINGLE-MINDED MIGRATORS.

>> WE'RE HEADED UP TO THE CREST OF THIS HILL... TO LOOK FOR ONE OF OUR RADIO- COLLARED DEER.

LAST NIGHT IT SENT A GPS LOCATION FROM RIGHT HERE, BUT THE DEER ARE ON THE MOVE RIGHT NOW.

THEY'RE MIGRATING TO TAKE ADVANTAGE OF THE GREEN WAVE.

SO RECENTLY THIS ENTIRE AREA WAS COVERED IN SNOW.

NOW THE DEER ARE TAKING ADVANTAGE OF THIS NEW GROWTH.

AND AS THE VEGETATION CHANGES ROWTH.

AND WE GET NEW GREEN UP FURTHER UP THE MOUNTAIN, THE DEER ARE MIGRATING TO TAKE ADVANTAGE OF THAT.

SOUNDS LIKE THAT DEER IS STILL HERE.

WE'RE GOING TO CONTINUE TO WATCH THESE DEER OVER THE NEXT FEW DAYS TO SEE HOW FAR THEY GO ON IN THEIR MIGRATION TOWARD SUMMER RANGE.

WE'VE JUST SEEN MULE DEER ON THE OTHER SIDE OF THE RESERVOIR ABOVE THE CLIFFS.

WE'RE ABOUT FOUR MILES FROM THE WINTER RANGE WHERE WE WERE A FEW DAYS AGO.

THESE DEER TRAVEL THESE MOUNTAINS TO GET TO THIS NARROW PART OF THE RESERVOIR WHERE THEY L SWIM ACROSS.

AND THEN ARE FUNNELED TO THE UNDERPASS, WHICH WAS BUILT OVER THEIR NATURAL MIGRATION ROUTE.

THIS UNDERPASS KEEPS THEM FROM BEING HIT BY CARS ON THE HIGHWAY.

ONCE THEY GET HERE, WE USE THESE TRAIL CAMERAS TO PHOTOGRAPH THEM GOING UNDER THE UNDERPASS.

FROM HERE THEY HAVE ABOUT 50 MILES TO GO AS THE CROW FLIES TO GET TO THEIR SUMMER RANGE.

IT'S RUGGED TERRAIN.

THERE ARE MORE HAZARDS ALONG THE WAY, BUT THEY'RE WELL ON THEIR E WAY RIGHT NOW TO HEAD TO SUMMER RANGE AND COMPLETE A REALLY INCREDIBLE MIGRATION.

>> Chang: AND THEY WILL KEEP MOVING, BUT, YOU KNOW, LAST NIGHT, WE WERE ABLE TO WITNESS A BIRTH.

WE SHOWED YOU THE CORNELL LAB OF ORNITHOLOGY.

THAT'S THEIR BIRD CAM.

RT AND WE ACTUALLY WATCHED-- LOOK IT, THAT'S THE LITTLE HE HATCHLING.

>> THAT'S THE HATCHLING FROM YESTERDAY, AND IF YOU LOOK RIGHT BEHIND IT, YOU CAN SEE THAT ANOTHER EGG IS-IS JUST BEGINNING TO HATCH.

YOU CAN SEE THAT, THAT LITTLE CHICK IN THERE PIPPING AT THE EGG.

UH, SO THERE'S A LOT OF ACTIVITY RIGHT NOW IN THIS LITTLE FAMILY.

>> Chang: AND THAT'S THE MOTHER BIRD, THE RED-TAILED HAWK, FEEDING THE CHICK AND KEEPING HER WARM, CLEARLY, BY SITTING RIGHT ON TOP OF IT.

IT LOOKS LIKE THE CHICK IS ABOUT TO GET A SIBLING.

AND THIS IS THE RED-TAILED HAWK HERE.

>> YES.

WE-WE SPOTTED THIS RED-TAILED HAWK EARLIER IN THE DAY, AND IT'S-IT'S-IT'S SOARING WITH THOSE BROAD WINGS ON THE THERMALS THAT ARE, THAT ARE BRINGING IT UP INTO THE SKY.

AND IF YOU LOOK CAREFULLY AT ITS WINGS, YOU'LL SEE THAT IT'S MOLTING A FLIGHT FEATHER.

YOU CAN SEE A GAP THERE IN THE LEFT WING WHEN IT TURNS.

>> Chang: I WOULD NEVER HAVE NOTICED THAT, HAD THAT NOT BEEN FOR YOU.

THANK YOU SO MUCH.

AND, CLEARLY, THAT RED-TAILED HAWK IS FLYING OVERHEAD.

IN A MEADOW NEARBY, THOUGH, HERE IN THE SIERRA NEVADA MOUNTAINS, IS ANOTHER MEMBER OF OUR SCIENCE TEAM, INSECT SCIENTIST PHIL TORRES, AND HE'S TRACKING SOME MAGNIFICENT MIGRATORS.

PHIL, WHAT HAVE YOU GOT?

CE >> HEY, YOU GUYS, I THINK WE'VE GOT A BUTTERFLY UP HERE.

IS IT IN THERE?

YES.

OKAY, WE GOT A BUTTERFLY LIVE ON TV.

HERE WE GO.

NOW... OH, THIS IS INCREDIBLE.

THIS IS THE PAINTED LADY I'VE BEEN LOOKING FOR ALL DAY.

AND I'M GOING TO GET IT OUT SO IS T WE CAN TAKE A CLOSER LOOK.

GIVE ME A SECOND HERE.

I'VE BEEN COLLECTING BUTTERFLIES FOR WELL OVER 20 YEARS, SO I CAN DO THIS IN A WAY THAT WILL BE VERY GENTLE WITH THE BUTTERFLY.

AND I'LL MAKE SURE I'M NOT HARMING IT.

E THAT'S WHY I HAVE THESE SPECIAL FORCEPS, TOO, SO... OH, LOOK AT THAT BEAUTY.

STAY IN THERE.

PLEASE COOPERATE.

I WANT TO SHOW YOU TO THE WORLD.

OH.

WHERE ARE YOU AT?

GUYS, THIS IS LIVE TV.

NO PRESSURE, RIGHT, JUST GOT TO GET A BUTTERFLY OUT OF HERE.

OKAY.

UR HOW WE DOING?

HOW WE DOING?

ALL RIGHT.

OH, AH, AND WE GOT IT.

ALL RIGHT.

LOOK AT THIS ABSOLUTELY BEAUTIFUL THING.

THIS IS THE PAINTED LADY BUTTERFLY.

NOW, I JUST LOVE THE COLORS L WE'RE SEEING HERE.

WE'VE BEEN TALKING ABOUT THAT GREEN WAVE OF PLANTS COMING THROUGH IN SPRING, AND THEN THE YELLOW WAVE OF FLOWERS LIKE THIS COMING THROUGH.

AND NOW WE HAVE THE WAVE OF MANY DIFFERENT COLORS THAT I LIKE TO CALL THE INSECTS AND THE BUTTERFLIES LIKE THIS.

THIS THING IS ABSOLUTELY STUNNING.

AND, LOOK, YOU CAN SEE ITS LITTLE STRAW-LIKE PROBOSCIS RIGHT THERE.

THAT'S HOW IT DRINKS FROM FLOWERS.

AND MY FAVORITE WAY OF RELEASING BUTTERFLIES WHEN I'M IN THE FIELD-- WE'RE GONNA TRY SOMETHING.

THIS IS LIVE TELEVISION.

I'M NOT SURE HOW IT'S GONNA WORK, BUT LET'S SEE IF IT'LL LAND RIGHT THERE.

IT'S WORKING.

ALL RIGHT.

E NOW, IF YOU LOVE BUTTERFLIES AS MUCH AS I DO, YOU ARE GOING TO LOVE THIS CITIZEN SCIENCE PROJECT.

IT IS CALLED THE MONARCH LARVA MONITORING PROJECT AND IT'S INCREDIBLE.

TAKE A LOOK.

T' >> HEY, THERE'S A MONARCH, RIGHT THERE.

>> NO WAY.

>> YEAH, RIGHT THERE, YOU SEE IT?

>> MY NAME IS CRAIG HENSLEY.

I'M A NATURALIST, AN EDUCATOR, AND TODAY I'M A CITIZEN SCIENTIST.

THE PROJECT WE'RE WORKING ON IS THE MONARCH LARVA MONITORING PROJECT.

WE'RE TRYING TO TAKE A LOOK AT THE MONARCH MIGRATION, AND WE'RE DOING THAT BY LOOKING FOR EGGS AND LARVA OF THE MONARCH BUTTERFLY.

THERE IT IS RIGHT THERE.

>> MM-HMM.

LOOKS PRETTY FRESH.

>> YEAH, THAT LOOKS PRETTY FRESH.

THE MONARCH BUTTERFLY HAS MULTIGENERATIONS THROUGHOUT THE YEAR.

R THIS GENERATION IS ACTUALLY THE LAST GENERATION OF LAST FALL.

THEY MADE THAT LONG-DISTANCE MIGRATION FROM ALL OVER THE EASTERN HALF OF THE UNITED STATES, ALL THE WAY TO THE MOUNTAINS OF MEXICO, AND THEY'RE COMING BACK HERE TO LAY EGGS RIGHT NOW.

IS THAT AN EGG?

>> THERE'S-- ACTUALLY, THAT SHADOW IS POINTING RIGHT TO IT.

>> JUST OVER THE EONS, THEY'VE ADAPTED TO FEEDING ON MILKWEED, HT WHICH ARE TOXIC PLANTS.

THEY'RE ABLE TO OVERCOME THE TOXICITY, AND IT ALSO PROTECTS THEM FROM A LOT OF DIFFERENT PREDATORS.

OH, THERE'S THE MONARCH RIGHT THERE.

NTS.

THEY HAVE OV THAT BRIGHT ORANGE AND BLACK, AND WITH WHITE SPOTS ON THAT PATTERN IS JUST LIKE A STOP SIGN THAT SAYS, "HEY, I TASTE BAD.

DON'T EVEN TRY."

AS A CITIZEN SCIENTIST, ONE OF THE GREAT JOYS I HAVE IS KNOWING THAT, A, I'M GONNA LEARN NEW THINGS.

B, I'M GOING TO B, THAT I GET TO ACTUALLY PARTICIPATE IN REAL SCIENCE, AND HOPEFULLY, THAT ALSO HELPS DICTATE AND DETERMINE WHAT KIND OF CONSERVATION EFFORTS WE MAKE ON A LOCAL, AND, HOPEFULLY, ON A NATIONAL BASIS.

OH, WE GOT A BIG CATERPILLAR.

IT'S A GREAT OPPORTUNITY FOR ME AND MY FELLOW CITIZEN SCIENTISTS TO MAKE A DIFFERENCE IN THE WORLD.

>> ALL RIGHT, YOU GUYS, WELL, I JUST ABSOLUTELY LOVE THOSE WORDS OF INSPIRATION THAT WE JUST SAW RIGHT THERE, BECAUSE THE MONARCHS NEED HELP.

THEIR POPULATION IS DOWN 90% SINCE 1995, WHICH IS JUST-- IT'S PRETTY DRASTIC.

AND A LOT OF IT HAS TO DO WITH THIS BEAUTIFUL PLANT RIGHT HERE.

IF YOU ASK ME MY FAVORITE PLANT, IT'S THIS ONE.

H THIS THIS IS THE MILKWEED.

NOW, IT HAS THAT WORD "WEED" IN IT, BUT I THINK THAT IS SUCH A LKWEED.

DISSERVICE.

I MEAN, LOOK AT THAT LITTLE FLOWER.

IT IS MAGNIFICENT AND IT IS IMPORTANT TO MONARCHS.

SCIENTISTS ESTIMATE WE NEED TO PLANT AT LEAST A BILLION MORE OF THESE PLANTS ACROSS AMERICA TO BRING THAT MONARCH POPULATION BACK, BECAUSE SO MANY OF THESE HAVE BEEN TAKEN OUT, UH, FROM HERBICIDES, FROM HABITAT LOSS.

SO WE NEED SOME, AND YOU KNOW WHAT, I'VE BEEN CHECKING THESE LEAVES-- THE MONARCHS LAY EGGS ON THE UNDERSIDE OF THESE-- EVERY DAY SINCE WE'VE BEEN OUT HERE, AND THERE'S NO MONARCH S ON EGGS.

AND, TO BE HONEST, THAT'S-THAT'S A LITTLE UPSETTING, BECAUSE THEY SHOULD BE HERE RIGHT NOW, BUT THEY AREN'T.

AND THERE'S A LOT OF REASONS WHY.

I THINK IN CALIFORNIA, ESPECIALLY, WE'VE BEEN DEALING WITH THIS HABITAT LOSS.

WE NEED NATIVE MILKWEEDS IN PLACES TO REALLY LET THE MONARCHS THRIVE.

BUT THIS THING'S INCREDIBLE.

WE ALSO SAW HUMMINGBIRDS COME HERE JUST A LITTLE BIT AGO.

I WISH IT WOULD VISIT RIGHT NOW, BUT I CAN SEE THERE'S SOME NATIVE BEES ON HERE.

I'M SEEING SOME BEETLES.

SO THIS IS MORE IMPORTANT FOR-- I MEAN, THIS IS IMPORTANT FOR ALL SORTS OF NATURE.

NOW, IF YOU WANT TO LEARN HOW TO MAKE THE IDEAL BUTTERFLY GARDEN, CHECK OUT OUR PBS NATURE FACEBOOK PAGE.

WE GOT SO MUCH INFO ON THERE.

AND WHILE YOU'RE ON THERE, WE WANT TO SEE YOUR QUESTIONS.

WE WANT TO SEE YOUR COMMENTS.

AND AAT THE END OF THE HOUR, WE'RE GOING TO BE ANSWERING THOSE QUESTIONS LIVE ON AIR.

AND SPEAKING OF QUESTIONS, WE ALSO HAVE SOME TRIVIA FOR YOU.

ALL RIGHT.

YOU READY?

WHICH SPRING MIGRATING ANIMAL GOES FARTHER?

IS IT THE MONARCH BUTTERFLY OR IS IT THE MEXICAN FREE-TAILED BAT THAT WE'VE BEEN WATCHING TONIGHT?

BATS OR BUTTERFLY?

YOU GUYS CHIME IN.

WE'LL LET YOU KNOW LATER.

BACK TO YOU.

>> Chang: THANKS SO MUCH, PHIL.

YOU KNOW, WE LIKE TO SAY AROUND HERE THAT CITIZEN SCIENCE CAN KS SO MUCH, PHIL.

YOU KNOW, WE LIKE TO SAY ARO HELP TURN VIEWERS INTO DOERS THROUGH THOSE PROJECTS.

AT CITIZEN SCIENTISTS SO WE ARE HAVING SOME HUNGRY CATERPILLARS HERE FROM THE, YOU T KNOW, CHILDHOOD BOOK FAME, AND ALSO SOME CHRYSALISES, RIGHT?

WHAT'S THE PLURAL OF THAT?

>> WELL, IT IS CHRYSALISES, AND THAT IS A REALLY REMARKABLE, UH, CHRYSALIS RIGHT THERE.

THAT IS A CHRYSALIS OF THE MONARCH BUTTERFLY.

AND IT'S A BEAUTIFUL THING IN ITS OWN RIGHT, BUT WHAT'S GOING ON INSIDE IS PERHAPS EVEN MORE HERE.

>> THAT'S BEAUTIFUL IN ITS OW REMARKABLE.

THE CATERPILLAR OF THE MONARCH EN MORE INSIDE THERE HAS LIQUEFIED, ESSENTIALLY, TURNED INTO GOOP, INSIDE THERE HAS LIQ AND ITS WHOLE BODY IS REARRANGING IN THAT GOOPY STATE TO TAKE THE FORM OF THE ADULT BUTTERFLY, WHICH WILL THEN EMERGE FROM THAT CHRYSALIS AND FLY ON ITS WAY.

>> Chang: AND YOU SAY MONARCHS DO THAT RAPIDLY BECAUSE THEY'RE MIGRATING OVER GENERATIONS, RIGHT?

>> THAT'S EXACTLY RIGHT.

BECAUSE THEY'RE MIGRATING, THEY WANT TO GET THAT DONE QUICKLY AND GET ON THE ROAD FOR MOST OF THAT-- MOST OF THE YEAR DURING THE MIGRATION.

AND WE ALSO HAVE SOME CATERPILLARS DOWN HERE ON THE FLOWERS THAT ARE FROM ANOTHER SPECIES WE'VE BEEN TALKING ABOUT, THE PAINTED LADY, ANOTHER MIGRATORY CAT-- OR MIGRATORY BUTTERFLY.

TE UM, BUT WHAT ALSO HAPPENS INSIDE THE CHRYSALIS, FOR SOME SPECIES IS-- THIS IS A STRATEGY OR IT CAN BE, TO GET THROUGH THE WINTER-- AND IN THAT CASE, THEN YOU HAVE A SITUATION WHERE TIMING BECOMES REALLY IMPORTANT AGAIN IN SPRINGTIME.

THAT PHENOLOGY, THOSE SEASONAL EVENTS WE'VE BEEN TALKING ABOUT.

BECAUSE YOU DON'T WANT TO EMERGE FROM THAT CHRYSALIS UNTIL THE RIGHT MOMENT WHEN THE PLANTS THAT YOU RELY UPON, FOR MONARCHS IT WOULD BE THE MILKWEED, ARE READY TO GIVE YOU WHAT YOU NEED.

>> Chang: AND IT MAY BE THE CATERPILLARS OR THE CHRYSALISES THAT ARE ATTRACTING THE RAVEN THAT JUST FLEW OVERHEAD AND THE RED-TAILED HAWK THAT SEEMS TO BE HANGING AROUND.

>> WELL, THAT'S A GOOD POINT, THOUGH, WITH THIS MONARCH, AND WITH THESE CATERPILLARS, IN THAT THE MONARCH, WHEN IT EATS THAT MILKWEED, TAKES ON THE TOXIN THAT MAKES IT REALLY TASTE HORRIBLE TO BIRDS.

SO IF ONE OF THOSE BIRDS DID COME DOWN, THEY WOULD HAVE A NASTY TREAT IN STORE.

>> Chang: THAT'S FASCINATING.

D DID COME SO LET'S CHECK IN WITH SOME OTHER SONGBIRDS.

THEY ARE THE MIGRATORY SONGBIRDS, AND THE SCIENTISTS FOLLOWING THEM AT MAD ISLAND MARSH PRESERVE OVER IN TEXAS.

>> HEY, JUJU.

WE ARE HERE WITH THE, UH, BIRDS IN THE BOX.

WE TOOK THEM OUT OF THE, UH, OUT OF THE NETS.

AND NOW WE'RE GONNA GO AHEAD AND BAND THEM.

I'M GONNA PULL OUT THIS BEAUTIFUL BIRD.

THIS IS AN INDIGO BUNTING.

I'LL PULL OUT THIS BEAUTIFUL BIRD.

THIS IS AN IND LOOK AT THAT GUY.

DANIELLE IS GONNA BAND THAT BIRD.

T I'M GONNA PULL OUT AN EVEN MORE AMAZING BIRD.

THIS IS A FEMALE SUMMER TANAGER.

UNFORTUNATELY, THIS SPECIES, LIKE SEVERAL OTHER SPECIES, IN FACT OVER 50% OF MIGRATORY SPECIES, ARE DECLINING SIGNIFICANTLY.

WE'VE SEEN JUST HORRIBLE, HORRIBLE DECLINES IN MANY OF THESE BIRDS.

HABITAT LOSS, CLIMATE CHANGE, THINGS LIKE CATS, AND PESTICIDES ARE ALL RESPONSIBLE FOR THESE DECLINES.

PESTICIDES ARE ALL RES WE DON'T KNOW EXACTLY WHERE THESE DECLINES ARE HAPPENING OR HOW, BUT WE DO KNOW THAT MOST OF THE DIRECT MORTALITY OCCURS H DURING SPRING MIGRATION.

AND IT'S SUCH A HARD PERIOD OF THE ANNUAL CYCLE TO-TO STUDY RS THESE BIRDS DURING THAT PERIOD, BECAUSE THE BIRDS ARE MOVING.

AND WE CAN'T TRACK THEM VERY EASILY.

BI SO HERE AT A BANDING STATION, WHAT WE TRY TO DO IS ASSEMBLE AS MANY CLUES AS WE POSSIBLY CAN THROUGH THE SAMPLING THAT WE DO, TO ACTUALLY TRY TO FIGURE OUT HOW THESE BIRDS ARE DOING.

SO THE FIRST THING THAT WE DO IS ACTUALLY BAND THE BIRD WITH A VERY LIGHTWEIGHT ALUMINUM BAND THAT HAS A UNIQUE NUMBER ON IT.

PUT THIS ON THE BIRD'S LEG LIKE SO.

AND SO IF SOMEBODY ELSE CATCHES THIS BIRD OR IF WE CATCH THIS BIRD AGAIN, WE'LL KNOW THIS WAS THE EXACT BIRD.

THEN WE DO A VARIETY OF MEASUREMENTS OF THE BIRD.

WE MEASURE ITS WING CORD.

90 FOR THE WING CORD.

WE MEASURE ITS TAIL... 60.

I'LL MEASURE ITS LEG OR ITS TARSUS.

21.35.

AND THEN WE'LL ACTUALLY WEIGH THE BIRD.

AND BY ASSEMBLING THE BODY SIZE OF THE BIRD AND THE WEIGHT OF GH THE BIRD.

BY ASS THE BIRD, WE CAN LOOK AT ITS CONDITION, JUST LIKE YOU WOULD IF YOU WENT TO THE DOCTOR'S OFFICE.

THE DOCTOR WOULD TAKE YOUR HEIGHT, LOOK AT YOUR WEIGHT, AND HE COULD TELL YOU WHETHER YOU'RE IN GOOD CONDITION OR NOT.

THIS BIRD WEIGHS 28 GRAMS.

THE OTHER THING WE'RE GONNA DO IS LOOK AT ITS FAT.

SO BEFORE THESE BIRDS START TO MIGRATE, THEY ACTUALLY ALMOST DOUBLE THEIR BODY SIZE.

THEY'LL PUT ON ALL KINDS OF FAT RIGHT IN THEIR THROAT AREA AND AROUND THEIR THIGHS.

AND THEY PUT THIS FAT ON BECAUSE WHEN THEY'RE GOING ON THIS NON-STOP MIGRATION, THEY NEED TO USE THOSE STORES, THOSE FAT STORES.

THEY DON'T WANT TO USE THEIR PROTEIN, BECAUSE THEY NEED THOSE MUSCLES TO POWER THAT FLIGHT.

SO THEY USE THIS FAT AS A QUICK T ENERGY STORE.

SO I'M GONNA BLOW RIGHT IN THE THROAT, AND SEE IS YOU CAN SEE SOME OF THE FAT THAT'S IN THERE.

IT'S THAT YELLOWISH SUBSTANCE THAT'S RIGHT IN THERE THAT'S THE FAT.

THE OTHER THING THAT WE REALLY WANT TO LEARN IN THIS ALMOST FORENSIC SCIENTIST SORT OF WAY IS WHERE THIS BIRD IS GOING.

AND SO WE'LL PULL A FEATHER FROM THE BIRD, AND THIS FEATHER THAT WAS GROWN LAST YEAR ON THE BREEDING GROUND CAN INCORPORATE EA A CHEMICAL SIGNATURE INTO IT.

HE AND WE CAN ACTUALLY ANALYZE THIS AND TELL YOU ROUGHLY WHERE THIS BIRD MOLTED THAT FEATHER OR WHERE IT'S GOING.

WE'LL ALSO CLIP A TOENAIL, AND ERE THAT TOENAIL WILL TELL US SOMETHING ABOUT THE HABITAT THAT THAT BIRD OCCUPIED ON THE WINTERING GROUNDS.

SO, BY ASSEMBLING ALL OF THESE CLUES, WE CAN ALMOST SOLVE A MURDER MYSTERY BY TRYING TO FIGURE OUT EXACTLY WHAT'S GOING ON WITH THIS BIRD.

HOW IS ITS CONDITION?

WHERE IS IT GOING?

WHERE DID IT COME FROM?

SO, WHEN WE BAND THESE BIRDS, WE LIKE TO MOVE THEM THROUGH PRETTY QUICKLY AND LET THEM GO AS FAST AS WE CAN SO THEY CAN HEAD ON THEIR WAY AND CONTINUE ON THEIR SPRING MIGRATION.

WE'LL LET THIS INDIGO BUNTING GO, AS WELL.

>> Chang: AND THAT IS DR. PETER MARRA.

HE IS A DEFT WILDLIFE PROFESSIONAL, RIGHT?

WE SHOULD NOT BE HANDLING BIRDS LIKE THAT AT HOME.

>> NO.

THAT'S NOTHING TO BE TAKEN LIGHTLY.

>> Chang: NOT AT ALL.

BUT LET'S TALK ABOUT A LITTLE SCIENCE HISTORY.

YOU KNOW, THOR, YOU AND I WERE TALKING ABOUT THE FACT THAT ONE BOUT SCIENCE OF THE FIRST CITIZEN SCIENTISTS WAS ACTUALLY HENRY DAVID THOREAU, WHO MADE ALL SORTS OF SCIENTIFIC OBSERVATIONS ON WALDEN POND.

>> IT'S TRUE.

AND ALSO, ODDLY ENOUGH, THE FIRST PERSON TO BAND A MIGRATORY SONGBIRD IN NORTH AMERICA WAS OU ALSO A CITIZEN SCIENTIST, A TEENAGER NAMED JOHN JAMES RATORY AUDUBON.

>> Chang: HE WAS CLEARLY THE INSPIRATION FOR THE AUDUBON SOCIETY.

NOW, WHEN WE THINK OF BIRDS TRAVELING IN A "V" FORMATION DURING THE DAY, THAT'S NOT ALWAYS HOW THEY MIGRATE, RIGHT?

THEY OFTEN DO THAT AT NIGHT.

>> THEY OFTEN DO THAT AT NIGHT.

NOW, LET'S TAKE A LOOK AT THIS GRAPHIC.

THIS IS A WEATHER RADAR IMAGE WHERE ALL THE WEATHER HAS BEEN REMOVED, AND WHAT YOU ARE SEEING S ARE CLOUDS OF BIRDS.

AND AT NIGHT, YOU CAN SEE HOW IT JUST LIGHTS UP.

MILLIONS UPON MILLIONS OF BIRDS MIGRATING IN THAT GENERALLY NORTHWARD DIRECTION DURING SPRINGTIME.

>> Chang: AND, YOU KNOW, UNTIL ERALLY NORTHWARD DIRECTION RECENTLY, SCIENTISTS HAVE HAD A REALLY HARD TIME TRACKING BIRDS AS THEY MIGRATE AT NIGHT, BUT ONE SCIENTIST HAS COME UP WITH T AN INGENIOUS SOLUTION ON SOUTH PADRE ISLAND IN TEXAS.

THAT'S WHERE BIRD EXPERT ANDY FARNSWORTH HAS A HIGH-TECH SOLUTION HE DEVELOPED FOR TRACKING HIGH-FLYING BIRDS AT NIGHT.

>> I'M HERE IN ONE OF THE MOST HEAVILY TRAFFICKED MIGRATION CORRIDORS ON THE PLANET.

AND BIRDS ARE JUST ABOUT TO START MIGRATING.

NOW, BECAUSE IT'S GOING TO BE DARK, I CAN'T USE THESE TO STUDY THESE MIGRATIONS, BUT I CAN USE SOME SPECIAL TECHNOLOGIES, IN S PARTICULAR, A RADAR.

IT'S PART OF THE BIRDCAST PROJECT.

WE USE RADAR TO STUDY HOW MANY BIRDS ARE ALOFT IN THE ATMOSPHERE, WHAT DIRECTION THEY'RE MOVING, WHAT SPEED, WHAT ALTITUDE, AND WE CAN SEE THIS IN REAL TIME.

WHAT I'M SEEING RIGHT NOW IS THAT BIRDS ARE JUST STARTING TO TAKE FLIGHT IN REALLY GOOD NUMBERS IN THE FLORIDA PENINSULA S AND ALSO IN SOME OTHER PARTS OF THE GULF COAST.

SUPER COOL.

NOW, WHAT I CAN'T SEE FROM RADAR AND WHAT I CAN'T TELL IS WHAT THESE BIRDS ARE.

I NEED ANOTHER KIND OF TECHNOLOGY TO DO THAT.

AND THAT IS AUDIO TECHNOLOGY.

THIS MAY NOT LOOK LIKE AUDIO TECHNOLOGY, BUT IT'S A HOMEMADE TH MICROPHONE.

YOU CAN MAKE ONE YOURSELF.

IT'S QUITE DURABLE AND MEANT TO STAY OUTSIDE FOR MONTHS AT A TIME.

I SET THE MICROPHONE OUT POINTING UP TO CAPTURE THE AUDIO OF BIRDS AS THEY'RE MIGRATING AT NIGHT AND USING SPECIAL DIO VOCALIZATIONS THAT IDENTIFY THEM TO SPECIES.

I CONNECT THE MICROPHONE TO MY COMPUTER.

AND I CAN VISUALIZE THAT AUDIO COMING IN.

I CAN LOOK AT THE FREQUENCY OF THOSE SOUNDS OVER TIME AND UNDERSTAND WHAT THOSE SPECIES ARE.

NOW, STUDYING MIGRATION IS R TIME AND UNDERSTAND WHAT THOSE SPECIES IMPORTANT BECAUSE OUR PLANET IS CHANGING AND BIRDS ARE REALLY EXCELLENT INDICATORS OF ECOSYSTEM HEALTH AND CHANGING AND BIRDS ARE REA ENVIRONMENT.

HUMANS ARE DRAMATICALLY ALTERING CLIMATE, HABITATS.

WE CAN EVEN SEE IT HERE IN THESE TWINKLING LIGHTS IN THE DISTANCE.

LIGHT POLLUTION IS INCREDIBLY DANGEROUS TO BIRDS THAT MIGRATE AT NIGHT.

THEY DID NOT EVOLVE WITH LIGHT.

THEY EVOLVED TO MIGRATE IN DARKNESS.

SO IT DISORIENTS THEM AND CAN BE EXTREMELY HAZARDOUS.

BUT WITH TECHNOLOGY, WE CAN TELL CITIES WHEN AND WHERE IT'S IMPORTANT TO TURN OFF THEIR LIGHTS TO SAVE BIRDS.

NOW, BIRDS ARE ABOUT TO START MIGRATING.

I'M GONNA STAY HERE AND CHECK OUT WHAT HAPPENS.

>> Chang: THANKS SO MUCH, ANDY.

AND, YOU KNOW, IT'S EASY TO FORGET THAT ON THESE EPIC MIGRATIONS, AS THEY TRAVEL THE WORLD, BIRDS DON'T JUST FLY OVER I FORESTS AND COUNTRY LANES.

THEY ALSO PASS THROUGH DENSELY POPULATED TOWNS AND CITIES.

SO IF YOU HAPPEN TO LIVE IN A CITY, PHIL HAS A WAY YOU CAN HELP TRACK THEM.

PHIL?

>> I ABSOLUTELY DO, BUT FIRST I JUST WANT TO TAKE A MOMENT TO APPRECIATE THIS BEAUTIFUL AFTERNOON WE GOT OUT HERE.

NOW, WE MAY NOT HAVE MIST NETS.

WE MAY NOT HAVE RADAR.

BUT WE'VE STILL BEEN SEEING SOME INCREDIBLE THINGS.

WE'VE SEEN SO MANY WOODPECKERS.

WE'VE SEEN WESTERN BLUEBIRD, THAT REALLY VIBRANT BLUE.

AND JUST TAKE MOMENT AND LISTEN.

THERE'S PROBABLY THREE OR FOUR DIFFERENT SPECIES WE'RE HEARING RIGHT NOW.

IT'S A GOOD DAY TO BE CELEBRATING SPRING.

NOW, LIKE YOU SAID, YOU DON'T HAVE TO BE WAY OUT HERE TO BE A CITIZEN SCIENTIST.

YOU CAN DO IT RIGHT IN A CITY, AND WE'RE ABOUT TO SHOW YOU A PROJECT THAT DOES IT JUST BEAUTIFULLY.

IT'S AT THE URBAN BEATS CENTER WE IN SAN DIEGO, AND THE PROJECT IS CALLED CELEBRATE URBAN BIRDS.

TAKE A LOOK.

>> WE SEE A BIRD FLYING IN ANY OF THIS, IMAGINE THERE'S A SQUARE.

THEN THOSE WILL BE THE BIRDS WE COUNT.

>> CELEBRATE URBAN BIRDS IS A CITIZEN SCIENCE PROJECT FOCUSED ON REACHING OUT TO COMMUNITIES THAT ARE NOT REPRESENTED IN THE SCIENCES.

>> LOOK, DID YOU SEE THAT?

>> IT'S A HUMMINGBIRD.

IT'S RIGHT THERE.

IT'S RIGHT IN THERE.

>> WE DON'T WANT THE SCIENCES TO JUST REFLECT ONE PARTICULAR WORLDVIEW.

>> DID ANYONE SEE THE AMERICAN CROW?

>> WE HAVE TO DO IT SIDE BY SIDE WITH PEOPLE FROM ALL DIFFERENT NEIGHBORHOODS, ALL DIFFERENT BACKGROUNDS.

>> THE BIRD NEEDS?

>> FOOD, WATER, SHELTER.

>> EVERYTHING THAT WE NEED.

NE AND WE'RE TRYING TO GET THE KIDS OFF OF TELEVISION AND JUST PUT THEM INTO NATURE.

FOR THE UNDERSERVED COMMUNITY TO GET THAT CHANCE IS INCREDIBLE.

>> HOPEFULLY WE'LL GET TONS OF NASTURTIUMS AND SUNFLOWERS COVERING THIS HILLSIDE.

>> WE'RE TRYING TO LET CHILDREN KNOW THAT SCIENCE IS FOR EVERYONE.

>> RIGHT THERE.

RIGHT THERE.

>> IT'S FLYING RIGHT THERE.

UP THERE.

>> OH, YEAH.

>> THESE KIDS ARE GOING TO REMEMBER THESE EXPERIENCES FROM CELEBRATE URBAN BIRDS AND SAY, "I SEE MYSELF IN THE SCIENCES."

>> I LEARNED TODAY I WAS A OM CITIZEN SCIENTIST.

B I WAS CHECKING OUT BIRDS, HOW THE SCIENCE AND STUFF WORKED OUT.

A CITIZEN SCIENTIST.

I WAS CHECKING OUT BIRDS, HO >> WE SAW THE ROCK PIGEON, AND THEN WE SAW THE HUMMINGBIRD.

>> OH, I SAW ONE UP THERE.

>> WE THOUGHT IT COULD BE A PIGEON, BUT WE DIDN'T KNOW.

>> WHEN SCIENTISTS HAVE A QUESTION AND ALL WE ARE HEARING IS ONE PERSPECTIVE, THAT DOESN'T MAKE IT COMPLETE.

A YOU KNOW, WE NEED ALL THE VOICES BECAUSE WE ALL LIVE ON THE SAME PLANET.

>> AW, THAT PROJECT, SO INCREDIBLE, GETTING THOSE KIDS OUT THERE LOOKING FOR NATURE, EVEN IN THE CITY.

NOW, I'VE BEEN LOOKING FOR NATURE IN HERE, AND THIS IS PRIME RATTLESNAKE, PRIME LIZARD N HABITAT, SO... AH, NO RATTLESNAKES YET TODAY, I BUT I'VE SEEN A WESTERN FENCE LIZARD.

I'VE SEEN THIS BRIGHT RED SKINK LIZARD.

AND IT'S BRIGHT RED BECAUSE IT'S SPRING, AND IT'S MATING TIME, AND IT'S KIND OF SHOWING OFF ITS COLORS.

IT'S BRIGHT RED BECAUSE IT'S BUT THAT PROJECT WAS INCREDIBLE.

AND YOU DON'T HAVE TO START WITH WI RATTLESNAKES LIKE I'M DOING IF YOU WANT TO CELEBRATE URBAN NATURE.

WHAT YOU CAN DO IS GO TO OUR PBS NATURE FACEBOOK PAGE AND START YOUR OWN URBAN BIRD GROUP.

AND WHILE YOU'RE ON THERE, YOU CAN ALSO ADD SOME COMMENTS, ADD UP.

SOME QUESTIONS, AND WE'RE GOING TO BE ANSWERING THOSE QUESTIONS AT THE END OF THE HOUR.

AND DON'T FORGET TO CHECK OUT SCISTARTER ON OUR AMERICAN SPRING LIVE WEBSITE AT PBS.ORG FOR EVEN MORE CITIZEN SCIENCE T PROJECTS.

BACK TO YOU GUYS.

>> Chang: THANKS SO MUCH, PHIL.

WE'RE GONNA INSPIRE AS MUCH SCIENCE AS WE CAN.

NOW, IN TEXAS, THE SUN RIGHT NOW IS GETTING LOWER IN THE SKY, WHICH MEANS INSECTS ARE STARTING TO EMERGE.

AND YOU KNOW WHAT THAT MEANS-- ONE THING FOR OUR HUNGRY BATS: DINNERTIME.

RG SO LET'S HEAD BACK TO BRACKEN CAVE OUTSIDE SAN ANTONIO WHERE DR. WINIFRED FRICK IS THERE TO SEE ONE OF THE WORLD'S MOST AMAZING EVENTS.

IT'S THE EMERGENCE OF A BAT COLONY THAT HAS LITERALLY MILLIONS OF BATS INSIDE.

>> AS YOU CAN SEE, WE'RE NOW AT THE ENTRANCE OF BRACKEN CAVE, N AND WE'RE STANDING HERE WATCHING ALL OF THE BATS EMERGE OUT INTO THE NIGHT SKY.

LET'S MOVE UP AND SEE IF WE CAN GET UNDERNEATH THIS INCREDIBLE VORTEX, THIS BATNADO.

WOW.

OH, MY GOODNESS.

IT'S-IT'S LIKE STANDING UNDER A SNOWSTORM OF BATS.

THEY'RE JUST SWIRLING OVERHEAD.

THEY FORM THIS VORTEX.

THEY'VE SPENT THIS...

THE LAST HOUR OR SO STAGING UP INSIDE THE CAVE, GETTING READY, TRYING TO OUR OR DECIDE ON THE RIGHT MOMENT OF WHEN TO COME OUT.

WE DON'T KNOW EXACTLY WHAT THE TRIGGER IS FOR THEM TO DECIDE WHEN TO COME OUT.

SOME NIGHTS IT'S EARLIER.

SOME NIGHTS IT'S LATER.

BUT WHEN THEY DO, IT'S JUST ONE OF THE MOST SPECTACULAR THINGS TO GET TO WITNESS.

YOU SEE THEY SWIRL AROUND, AND THERE ARE SO MANY OF THEM, YOU CAN HEAR THEIR WINGS HITTING EACH OTHER IF YOU LISTEN.

EA THAT'S THE SOUND OF THEIR WINGS, AND AS THEY FLY UP, THEY'LL HIT THE TOPS OF THESE TREES, AND THEN THEY'LL FORM THESE RIVERS OUT OVER THE LANDSCAPE.

AND THEY'LL FLY FOR 60 MILES OUT OVER THIS TEXAS LANDSCAPE OVER AGRICULTURAL FIELDS AND NATURAL HABITATS, THE WHOLE TIME HUNTING FOR INSECTS.

AND THIS COLONY, WHICH IS THE LARGEST COLONY OF MEXICAN FREE-TAILED BATS IN THE WHOLE WORLD, THERE ARE SO MANY BATS THAT COME OUT EVERY NIGHT -T LOOKING FOR INSECTS THAT THEY'LL, LIKE, EAT 150 TONS OF INSECTS IN ONE NIGHT.

THAT'S LIKE 20 TO 30 SCHOOL BUSES IN WEIGHT OF INSECTS.

AND SOME OF THOSE INSECTS DO TERRIBLE CROP DAMAGE TO THE FARMERS, SO THESE BATS ARE HELPING ALL THE LOCAL FARMERS HERE BY EATING DIFFERENT KINDS OF INSECTS.

SO, WE TAKE A LOOK BACK INTO THE CAVE.

WE CAN SEE HOW MANY MORE BATS ARE COMING OUT.

'CAUSE THIS CAN LAST FOR HOURS, 'CAUSE THERE ARE SO MANY BATS THAT LIVE IN THIS CAVE.

AND THEY'RE ALL COMING OUT.

NOW, BATS AREN'T BLIND.

SOMETIMES PEOPLE THINK BATS ARE BLIND, BUT THEY'RE USING ECHOLOCATION.

THEY'RE USING SOUND.

THEY-- THEIR SOUND IS HIGHER THAN OUR HUMAN EARS CAN HEAR, ND BUT THEY USE IT TO NAVIGATE OUT.

AND THERE ARE SO MANY OF 'EM.

SOMETIMES THEY BUMP INTO EACH OTHER.

THEY MIGHT BUMP INTO ME.

IN ALL MY 20 YEARS OF STUDYING BATS, THIS JUST NEVER GETS OLD.

THIS KIND OF REMARKABLE EXPERIENCE OF GETTING TO WATCH THESE BATS COME OUT, IT'S JUST E A INCREDIBLE, INCREDIBLE THING TO EXPERIENCE AND A DREAM COME TRUE FOR ME TO BE ABLE TO SHARE IT WITH EVERYONE.

ME WOW.

THEY'RE JUST SWIRLING AND SWIRLING.

IT'S LIKE A RIVER UP OVER THE TREES.

OH, AND I'M GETTING PEED ON, TOO.

>> Chang: WHAT AN INTREPID RESEARCHER.

DR. WINIFRED FRICK FROM THAT BAT CAVE.

SHE LITERALLY CALLS IT A BATNADO, AS IT'S SWIRLING AROUND HER.

>> YEAH, AND THE BATS ARE SO DENSE IN THAT CLOUD THAT NEARBY RANDOLPH AIR FORCE BASE HAS TO LIMIT FLIGHT ACTIVITIES ON THE NIGHTS THE BATS EMERGE.

>> Chang: IT IS REMARKABLE.

NOW, EARLIER, WE ASKED YOU TO ANSWER OUR SCIENCE QUESTION ON OUR FACEBOOK PAGE.

THAT'S WHAT PHIL ASKED.

WHAT SPECIES MIGRATES FURTHER, THE MONARCH BUTTERFLY OR THE FREE-TAILED BAT?

A AND, THOR, THE ANSWER IS?

>> THE ANSWER IS THE MONARCH BUTTERFLY.

AS WE MENTIONED EARLIER, MONARCHS MIGRATE OVER GENERATIONS.

AND IF YOU ADD UP ALL THOSE GENERATIONS, THEY'LL TRAVEL AS FAR AS 3,000 MILES.

>> Chang: THAT'S INCREDIBLE.

NOW, EARLIER, WE LOOKED IN A POPULAR STOP FOR MIGRATING SHOREBIRDS, COURTESY OF AN INGENIOUS FLOATING BIRD BLIND.

IT'S A ONE-OF-A-KIND ITEM.

LET'S SEE HOW IT'S GOING NOW OUT ON THE COASTAL FLATS OF VIRGINIA.

OU HIDDEN IN HIS BLIND AND CAPTURING THE ACTION IS OUR O WILDLIFE CINEMATOGRAPHER MICHAEL MALE.

MICHAEL, WHAT DO YOU SEE IN THERE?

>> I'M STILL HERE IN MY, UH... MY FLOATING BLIND.

UM, IT'S GOTTEN TOO DARK TO FILM, REALLY, BUT-BUT, UH, I JUST LIKE BEING OUT HERE, BEING ABLE TO-- THIS THING IS GREAT FOR BEING ABLE TO MOVE, UH, CLOSE TO THE BIRDS AND-AND SEE WHAT'S GOING ON.

A COUPLE OF CLAPPER RAILS JUST BI CAME DOWN TO THE EDGE AND-AND WERE CATCHING FIDDLER CRABS.

A COUPLE CL UM... AND THERE'S UNFORTUNATELY NOTHING I CAN SHOW YOU HERE NOW, BUT, UH..

BUT, UH, WE CAN-- WE CAN HAVE A LOOK AT WHAT I SHOT EARLIER IN THE DAY, WHICH WAS, UH...

IT WAS PRETTY COOL.

ALL KINDS OF BIRDS OUT THERE.

THIS TIME OF YEAR, IT'S JUST AMAZING HOW-HOW QUICKLY THE NUMBERS OF-OF ALL THESE SHOREBIRDS OUT IN THE MUD FLATS BUILDS UP.

IN THE MUD FLA UM, AND THEY'RE HERE FOR MAYBE FIVE WEEKS, SIX WEEKS, SOME OF THEM.

SOME OF THEM HAVE SPENT THE WINTER HERE, A FEW, BUT-BUT MANY KS OF THEM ARE COMING FROM, UH, REALLY FAR SOUTH, LIKE-LIKE TIERRA DEL FUEGO.

I'VE SPENT TIME WITH THESE BIRDS IN, UH, SOUTH AMERICA, WHERE THEY'RE SPENDING OUR WINTER, AND IN THE HIGH ARCTIC, WHERE THEY-- WHERE THEY NEST.

AND WHAT I REAL-- WHAT REALLY GETS ME EXCITED IS WHEN I'M HOME AND THEY VISIT MY NEIGHBORHOOD, CI BECAUSE TH-THIS, THIS IS SUCH A RICH SPOT RIGHT HERE, THIS ESTUARY.

UM, THEY-- THERE'S JUST AMAZING NUMBERS OF-OF SHOREBIRDS HERE EVERY-EVERY SPRING AT THIS TIME.

IT'S-IT'S, UM... FOR ME, IT'S-IT'S JUST SUPER EXCITING THAT THEY-THEY COME TO MY NEIGHBORHOOD.

FOR THEM, IT'S...

THEY'RE THESE BIRDS.

THEY HAVE THESE NEIGHBORHOODS ALL UP AND DOWN THE HEMISPHERE.

THEY-THEY LIVE COMPLETELY DIFFERENT LIVES THAN US.

THEY-THEY, UM... THEY-THEY COME TO THIS SPOT.

THEY KNOW CERTAIN, UM, PLACES TO-TO FEED, AND-AND THEY RETURN TO IT YEAR AFTER YEAR, THE TA SAME-SAME INDIVIDUALS.

RE THIS IS LIKE A TRUCK STOP TO 'EM.

THEY-THEY, UH...

THIS IS THEIR REST STOP, THEIR REFUELING SPOT.

>> ALL RIGHT.

WELL, WE KNOW IT'S GETTING TO THE END OF THE "AMERICAN SPRING LIVE" HOUR BECAUSE THESE FLOWERS ARE TELLING US SO.

LOOK, THIS ONE'S STILL OPEN, BUT THESE GUYS ARE KIND OF GOING TO SLEEP UNTIL TOMORROW.

YOU CAN SEE 'EM CLOSING UP ALREADY.

BUT, I PROMISE YOU, TOMORROW, THEY'LL BE, PFF, BACK, BRIGHT, AND OPEN, READY FOR SOME POLLINATORS.

NOW, EARLIER TODAY, WE ASKED YOU TO-- FOR SOME QUESTIONS ON FACEBOOK.

AND, WHAT DO YOU KNOW, WE GOT SOME ANSWERS RIGHT NOW.

SO, FROM DOREAN, SHE SAID, "HOW LONG DOES A RED-TAILED HAWK STAY IN THE NEST?"

WE SAW THOSE CHICKS.

ADORABLE.

IT TAKES 'EM ABOUT SIX WEEKS OF STAYING IN THAT NEST TO GET BIG ENOUGH TO FINALLY FLEDGE AND FLY OFF ON THEIR OWN.

AND, WHEN THEY'RE OUT THERE, THEY IMMEDIATELY START LEARNING HOW TO HUNT.

OFF ON THEIR OWN.

NOW, IN CENTRAL PARK OF NEW YORK, I GET TO SEE THIS ALL THE TIME, THESE JUVENILE RED-TAILED HAWKS THAT ARE JUST LEARNING HOW TO HUNT.

AND THEY ALWAYS GO FOR THE WRONG THING.

THEY TRY TO GET A SONGBIRD, BUT, J REALLY, THEY SHOULD BE GOING FOR A SQUIRREL OR A PIGEON.

AND, EVENTUALLY, THEY LEARN OUT THERE.

NOW, QUESTION FROM AMANDA.

UH, "WHAT ARE SOME EXAMPLES OF BUTTERFLY FRIENDLY PLANTS?"

A WELL, I MEAN, IF THERE'S ONE PLANT YOU'RE GONNA PLANT IN YOUR YARD, MAKE IT A MILKWEED, A NATIVE MILKWEED.

SO FIND OUT WHAT SPECIES IS NATIVE TO YOUR AREA.

UH, DEVEEN, SIMILAR QUESTION-- "HOW MANY EGGS DO MONARCH BUTTERFLIES LAY?"

WELL, THEY LAY ABOUT 500 EGGS, BUT THEY DON'T DO IT ALL AT ONCE.

THEY DO IT ONE OR TWO AT A TIME.

TERFLY SO A SINGLE MILKWEED PLANT WILL PROBABLY HAVE ONE OR TWO OR THREE EGGS ON IT, SO ONE OR TWO OR THREE CATERPILLARS, WHICH IS STILL A PRETTY GOOD SHOW IF YOU GET TO SEE THEM IN ACTION.

UM, WE HAVE ONE COMMENT FROM SAM, "LOVE THE SHOW.

UH, 14-YEAR-OLD DAUGHTER WILL LOVE IT, TOO."

THANK YOU.

UM, YOU KNOW WHAT, GUYS, KEEP THOSE COMMENTS COMING.

WE'LL BE BACK HERE TOMORROW NIGHT, AND I'LL BE IN YOSEMITE'S ICONIC MERCED RIVER.

AND I'M GOING RIVER RAFTING FOR SCIENCE.

GET READY.

>> Chang: THANKS SO MUCH, PHIL.

I'VE LEARNED SO MUCH SCIENCE FROM YOU.

AND THANK YOU, TOO, THOR, FOR ALL THE KNOWLEDGE.

THANK YOU FOR JOINING US FOR TONIGHT'S MIGRATION THROUGH THE SCIENCE OF SPRING.

TOMORROW NIGHT, WE'LL BE BACK AGAIN LIVE, HERE AT SEQUOIA NATIONAL PARK, FROM ACROSS THE COUNTRY AS WELL, WITH A LOOK AT THE UNIQUE AND OFTEN SURPRISING CONNECTIONS FORGED IN SPRINGTIME.

AT WE FOUND A MOTHER WOLF IN MINNESOTA, FOR EXAMPLE, STRUGGLING TO SAVE HER PUPS FROM THIS YEAR'S HEAVY SNOW MELT, AND OR ANOTHER APEX PREDATOR, THE BOBCAT, MAKING A SURPRISE DAYTIME APPEARANCE IN NORTHERN CALIFORNIA.

PLUS, WE'LL BE CREATING AN ACTUAL BEE SWARM AND BRINGING IT TO YOU LIVE IN A WAY YOU'VE NEVER SEEN BEFORE.

THOR, PHIL, AND I WILL SEE YOU RIGHT BACK HERE TOMORROW NIGHT.

THOR?

>> WELL, BY MY COUNT, THAT GIVES YOU 23 HOURS TO GET OUTSIDE OR TUNE IN TO A BIRD CAM AND EXPERIENCE A LITTLE BIT OF SPRING YOURSELF AND LOOK CLOSELY AND BE AMAZED.

>> Chang: IT GIVES US ALL A CHANCE TO COMMIT SCIENCE.

K CLOSELY AND BE FROM ALL OF US HERE AT "AMERICAN SPRING LIVE," THANKS FOR WATCHING.

SEE YOU TOMORROW.

ng >> WE WANT YOU TO PARTICIPATE IN THIS BROADCAST.

SO HEAD TO THE PBS NATURE FACEBOOK PAGE TO ASK US QUESTIONS, SHARE SPRING STORIES, AND POST YOUR PHOTOS AND VIDEO.

YOU CAN ALSO VISIT NATURE'S WEBSITE TO LEARN HOW TO BECOME A CITIZEN SCIENTIST, PLAY A PART, AND MAKE A DIFFERENCE IN THE PURSUIT OF CRITICAL DATA ABOUT SPRING.

>> THIS IS HOW WE GET THE BIG PICTURE OF WHAT'S HAPPENING IN Captioning sponsored by WNET Captioned by Media Access Group at WGBH access.wgbh.org