♪♪ -There's a story unfolding on the west coast of Costa Rica -- a story both ancient and new... a tale of two creatures from opposite worlds, each on a comeback from their own devastating declines.

One is the sea turtle, the global ocean traveler.

♪♪ The other, a magnificent cat -- the top predators in Central America.

♪♪ The return of an endangered forest will bring them together in an uncommon clash of land and sea -- a surprising encounter of a rare predator and a most unusual prey.

♪♪ How will their fates play out when they finally meet on one special crescent of sand... called Jaguar Beach?

♪♪ ♪♪ ♪♪ -Off the shore of Central America, in the shallows of the Pacific, an ancient ritual is underway.

♪♪ After more than a decade at sea, an olive ridley sea turtle nears the end of her long migration.

Guided by the Earth's magnetic field, she has navigated thousands of kilometers, seeking out the very beach where she was born.

[ Waves crashing ] ♪♪ ♪♪ This secluded crescent of sand has long provided a refuge for one of the world's most beloved creatures... and is home to a wild coastal community.

♪♪ Shorebirds flock to its shallows to feed... under the pterodactyl silhouettes of magnificent frigatebirds.

[ Birds calling ] American crocodiles slip out of their swampy lagoons for an occasional saltwater splash.

[ Waves crashing ] Rising up from the beach is one of the last habitats of its kind on Earth -- a tropical forest that's dry for half the year.

Restored as a national park after it had been clearcut for agriculture, its tangled woodlands sprawl nearly 500 square kilometers across Costa Rica's mountainous west.

♪♪ The forest stretches all the way to the ocean's edge, where its mangrove tendrils filter freshwater from salt.

♪♪ ♪♪ The hardy trees provide a home for over 250 species of birds.

♪♪ [ Bird squawking ] Yellow-naped parrots nest in the heights.

Orange-fronted parakeets feast on its floral buffet.

♪♪ They share the canopy with gymnastic spider monkeys... [ Monkey hooting ] ...and howlers.

♪♪ And in the understory, lumbering Baird's tapirs forage for fallen fruit.

[ Water trickling ] [ Waves crashing ] The unusual forest opens onto a pristine strip of sand -- one of only a few in the world where olive ridley sea turtles nest en masse.

For nearly two decades, biologist Luis Fonseca has been trekking to this remote alcove to monitor nesting sea turtles.

But after five years on the beach, he arrived one morning to a shock -- signs in the sand that he and the turtles were not alone.

-Empezamos a encontrar huellas en la playa y también de jaguares.

-The first tracks were no aberration.

He soon saw more evidence that one of the most formidable predators in the Americas was making a comeback in the dry forest.

-La población de jaguares ha empezado a incrementarse casi que exponencialmente en la última década.

Nosotros podemos decir que pasamos de tener casi cero jaguares en los primeros años hasta tener casi 40 individuos al final del último año de investigación.

-The return of an apex predator was bound to send ripples through the ecosystem... [ Jaguar growling ] ...so Luis decided to expand his research to include the jaguars.

Hoping to learn what impact they would have on the turtles, he set up hundreds of camera traps to capture their movements and behavior.

♪♪ And then he waited... for the turtles to emerge from the sea.

♪♪ For years at a time, olive ridley sea turtles live a solitary, nomadic life at sea.

♪♪ Their world is one of mighty behemoths and lively schools of dolphins.

[ Dolphins calling ] ♪♪ Then, every year or two, a primeval instinct draws them home to these shores.

Male turtles -- identifiable by their longer tails -- rarely return to land after hatching.

♪♪ But during nesting season, these ancient mariners patrol the shallows looking for mates.

♪♪ ♪♪ Seduction begins with a tender but clunky embrace.

The male uses long claws on his front flippers to hook onto the female's shell.

♪♪ The courtship is quick, but the coupling can last for several hours.

♪♪ The female does most of the work, constantly pushing to the surface so they both can breathe.

♪♪ ♪♪ For these two ocean wanderers and their species, it's a fleeting but critical connection.

♪♪ [ Waves crashing ] Weeks later, the female drags herself from the comfort of her weightless, watery world.

[ Waves continue crashing ] With her 50-kilogram frame and short flippers, she's far more graceful at sea than ashore.

But she's determined to find a good spot for her nest.

Then, she starts to carve out a deep, protective cavity.

As she digs, another mother-to-be emerges from the surf, carrying her own precious cargo.

[ Waves crashing ] In a few months, this sliver of beach will draw thousands of sea turtles for a mass nesting event.

But for now, she and the other female seem to have it all to themselves.

[ Waves continue crashing ] ♪♪ ♪♪ Within the forest, the area's dominant male jaguar -- named Alonzo by Luis -- sets off on a midnight hunt.

♪♪ ♪♪ On the beach, the first female turtle puts the final touches on her nest.

Her eggs are now hidden, but she is still very much exposed.

♪♪ ♪♪ [ Jaguar growls ] ♪♪ No stalking, no pouncing.

Just a quick and easy bite to the back of the head.

♪♪ [ Jaguar snarling softly ] [ Waves crashing ] Back in the mangroves, Alonzo settles down to his meal.

[ Crunching ] His powerful jaws make quick work of the turtle's hard shell.

The jaguar has the most powerful bite of any big cat.

His jaws work just as well on the shell as they do on other animals' skulls.

♪♪ ♪♪ His tongue isn't just for tasting.

It's lined with back-facing barbs that may aid with stripping flesh from bone.

♪♪ With Alonzo otherwise occupied, the other nesting female is still hard at work.

[ Waves crashing ] ♪♪ ♪♪ Around a hundred eggs tumble into the nest.

Soft, leathery shells cushion their fall.

♪♪ In her final maternal act, she carefully conceals them.

♪♪ Then, she returns to her ocean world, never to know what becomes of her clutch.

[ Waves crashing ] Her eggs must now survive the next 45 days -- hidden in the sand on a beach where everyone is looking for their next meal.

[ Waves continue crashing ] Back in the mangroves, the turtle will feed Alonzo for two days.

For now, he has eaten his fill.

But he's not the only one dining tonight.

♪♪ As he takes a break, hungry scavengers move in from the shadows.

♪♪ The scent penetrates the forest.

♪♪ A resourceful opossum is in luck.

He's so taken by his windfall, he fails to notice that someone has come back for seconds.

♪♪ ♪♪ ♪♪ The jaguar's leftovers will nourish a whole forest community.

But Luis is concerned for the turtles, because olive ridleys are in decline around the world.

How will the growing jaguar population affect the vulnerable turtles staging their own comeback here on this critical beach?

[ Insects, birds chirping ] Luis hopes his camera traps can offer some clues.

-Nosotros sabemos que los jaguares posiblemente en la noche pueden caminar por acá e incluso acostarse, descansar y esperar que salga una tortuga.

Entonces, por eso sabemos que este es un buen lugar para colocar una cámara trampa.

[ Waves crashing in distance ] Es como sin nosotros tuviéramos un asistente de investigación que estuviera escondido aquí, protegido dentro de este árbol y estuviera con una cámara esperando a que un jaguar pase.

♪♪ -The cameras reveal a secret no one expected -- constant traffic of jaguars moving between the dry forest and the beach.

What was once a sanctuary for Luis's nesting sea turtles has become a favorite hunting ground for a forest predator.

♪♪ It's an amazing comeback story for the big cats.

♪♪ During the 1950s and '60s, Costa Rica's northwestern coast was stripped of its trees -- replaced by a patchwork of cattle ranches.

Jaguars and other forest animals all but disappeared.

[ Lowing ] Then, in 1971, Costa Rica created Santa Rosa National Park and let nature rebuild the forest.

♪♪ ♪♪ New growth stretched across the province, eventually connecting the coast to an inland jaguar habitat.

♪♪ One by one, the cats followed the lure of the resurrected forest.

They found their way deeper into the park, expanding their territory... all the way to the beach.

[ Waves crashing ] -Está alimentando y de repente, amarra un pedazo de aleta... -To monitor the effects of this surge of predators, Luis assembled a small team with a passion for jaguars... and the patience and fortitude to work in extreme isolation.

♪♪ ♪♪ -Cuando eres un niño todo el mundo te pregunta cuál es el trabajo que quieres hacer de mayor.

¿Quieres ser astronauta?

¿Quieres ser bailarino?

Yo quería trabajar con animales.

Ser biólogo y trabajar en el campo es lo que te permite vivir los animales y aprender mucho de ellos sin tener que estar detrás de una pantalla o tener que estar leyendo en un libro, porque es mucho más diferente.

♪♪ Además, aquí estamos en un lugar donde podemos estudiar uno de los animales más elusivos que existen.

-These elusive animals are what drew Carolina Perez from her home in Italy to this rugged coastal outpost, several hours' drive and a mountain hike from the nearest town.

With only a flashlight and a bag of batteries, she monitors the project's cameras.

♪♪ They have captured some fascinating consequences of the jaguars' return.

-El jaguar se come una tortuga.

Pasa unas horas ahí comiendo.

Cuando está lleno, deja ahí la tortuga a la carcasa.

Y esa carcasa es disponible para un gran número de especies que normalmente no actúan como scavengers.

La presencia del jaguar da la posibilidad a otras especies de alimentarse.

♪♪ -Even pumas -- top predators themselves -- have altered their behavior.

They've become more active during the day to avoid the new rulers of the night.

And they're not above jaguar leftovers if it means a free meal.

-Por lo que estamos viendo, gracias al trabajo de cámaras trampa es también la relación, o sea, la importancia del jaguar en el ecosistema.

No es simplemente la tortuga y el jaguar, sino todo lo que pasa en el área alrededor de la playa.

♪♪ -The team's cameras are offering other revelations as well.

Normally, a single male jaguar needs 130 square kilometers of territory to himself.

♪♪ Here, an abundance of turtles keeps competition for food low, and these intensely solitary cats live in much closer proximity.

This gives Luis's cameras an unprecedented view into their social lives.

-A veces tenemos en una misma noche, en una misma playa, hasta cuatro machos diferentes, e incluso compartiendo su presa.

-Luis has recorded jaguars mating... wrestling... and even carting off an ill-fated dolphin.

♪♪ ♪♪ The project identifies the individual cats by their rosettes -- the spots on their fur.

Each jaguar's pattern is as unique as a human fingerprint.

♪♪ In the last 10 years, Luis's team has documented and named around 40 individual jaguars.

And they're capturing not just behaviors, but personalities.

Alonzo, the 12-year-old dominant male, asserts his right to any female -- or food -- on the beach.

Amanda, highly territorial, she seems to be the dominant female.

♪♪ And Jorge, a young tough on the cusp of adulthood.

He's been gravitating towards the females in heat.

♪♪ [ Waves crashing ] Tonight, Jorge is on the prowl... heading to the beach in search of an easy meal.

And he's well-equipped to spot one.

His eyes are backed with a mirror-like tissue that reflects light into his retinas and gives all cats their famous night vision.

[ Waves continue crashing ] Tonight, he finds no turtles, but something for other appetites.

It's Amanda, enjoying her own turtle catch.

Jorge is eager to put his adolescent prowess to the test.

[ Waves continue crashing ] In this rare peek into jaguar courtship, Jorge and Amanda take playful breaks between couplings.

[ Waves continue crashing ] ♪♪ But the interlude is cut short when Alonzo arrives.

♪♪ [ Jaguars snarling ] ♪♪ Jorge beats a hasty retreat.

Still outranked by Alonzo, he'll have to settle for a fleeting tryst.

[ Insects chirping ] For now, he heads back to the forest to wait out the heat.

Early April.

At the peak of dry season, the sun bakes the canopy.

As streams dry up, tensions rise.

[ Birds singing, monkeys screeching ] A trip to one of the few remaining watering holes now means risking a run-in with a thirsty predator.

A family of white-faced capuchin monkeys shelters high in the canopy.

But the heat is unrelenting, and while mom naps, a young capuchin takes his brother on a daring mission... ...to drink from a small seep in the ground.

[ Bees buzzing ] Bees have beaten them to it.

He endures the thirsty swarm for a few precious drops.

[ Buzzing continues ] His brother isn't quite convinced it's worth it.

The sun beats down across the park.

From the forest to the beach, life slows to a crawl.

Even offshore, the coastal breeze offers little relief to a colony of magnificent frigate birds.

[ Birds calling ] A young mom-to-be languishes in the heat, shielding her single egg from the relentless sun.

She'll remain on the nest for the next eight weeks, leaving only for brief spells to find food and water.

[ Birds continue calling ] [ Insects chirping ] ♪♪ Inside the forest, Amanda is also looking for water.

♪♪ But Luis's cameras catch someone else on the hunt.

♪♪ ♪♪ Jorge is more interested in a private moment than a drink.

♪♪ [ Jaguars snarling softly ] ♪♪ Amanda puts on a half-hearted show of resistance.

♪♪ [ Jaguar whines ] The coupling takes less than a minute.

Fast work, but jaguars can mate dozens of times a day.

♪♪ ♪♪ In between mating, the couple takes a stroll.

♪♪ Using scent glands in his cheeks, Jorge lays his claim to this swath of forest.

[ Jaguar growling softly ] It seems the young upstart has stepped out of Alonzo's shadow.

[ Thunder booming ] ♪♪ Late May -- the beginning of the wet season in the dry forest.

♪♪ A meter of rain falls in just the first three weeks.

[ Thunder booms ] The forest springs to life.

♪♪ ♪♪ In the next five months, over 90% of the year's rain will fall.

♪♪ Long-dry riverbeds begin to flow -- a wave of relief for the parched forest.

♪♪ ♪♪ A slow greening spreads across the hills, transforming Santa Rosa into a coastal oasis.

♪♪ ♪♪ Capuchins feast on nuts and ripe berries.

♪♪ ♪♪ A woodpecker chick gets her food delivered right to the nest.

♪♪ And as the forest begins to stir, the promise of new life also arrives by sea.

[ Waves crashing ] Late summer.

August winds bring an air of anticipation.

♪♪ Beyond the break, female olive ridley sea turtles begin to assemble.

♪♪ ♪♪ They're one of only two turtle species that gather in a synchronized mass nesting event -- an arribada -- Spanish for "arrival."

♪♪ The first few females converge offshore.

Soon, hundreds arrive.

♪♪ ♪♪ The shallows fill with a constellation of turtles.

They're all waiting for a mysterious signal humans have yet to decipher... ♪♪ ...a cue that the time is right to head ashore.

♪♪ ♪♪ ♪♪ Over the next few months, thousands will pour forth from the ocean -- an armada of mothers, bringing the next generation to the sand.

♪♪ ♪♪ It's one of the natural world's timeless and spectacular sights... a ritual of renewal that may date back to the age of the dinosaurs.

♪♪ [ Waves crashing ] The beach becomes a sea of churning sand.

In a single season, this small crescent -- just over a kilometer long -- will be filled with up to seven million eggs.

But on Jaguar Beach, a successful hatch is far from guaranteed.

As the arribada subsides, Carolina gets to work.

-Todas las noches hacemos patrullamientos nocturnos con el objetivo de marcar tortugas marinas.

Hola, pequeña.

Lo que tenemos en el proyecto son unas placas metálicas que tienen un número para poder identificar la tortuga.

Si es que vuelve en esta misma playa o en otras playas.

[ Waves crashing ] Lo que estamos haciendo de momento es marcar un nido... Luego, durante la arribada ya marcamos, si es posible, 200 nidos, y luego hay que esperar 45 días.

[ Waves continue crashing ] -These 45 days mark a dangerous period for the baby turtles.

As they incubate in the sand, relentless predators stalk them from above.

[ Birds squawking ] [ Waves crashing ] On most nesting beaches, wild dogs, foxes and coyotes -- so-called mesopredators -- plunder nests for the protein-packed eggs.

Using the tools of shoestring science, Carolina is trying to track how many of these nests will be raided.

-Marcamos el nido con una botella que está atada a una cuerda.

Así que esto nos sirve para monitorear el nido a ver si ha habido una depredación en el nido.

[ Waves crashing ] -The bottles make it easy to see if a nest has been disturbed.

During recent arribadas, the bottles have helped them document an encouraging trend that they believe is tied to the return of the jaguars.

-Lo que pensamos que está pasando es que la presencia de un gran depredador, como el jaguar, va a regular los números de coyotes y de otros individuos que están en la playa para depredar los nidos.

-It seems the jaguars are keeping smaller predators off the beach -- inadvertently protecting the turtles' eggs.

As Carolina works, she's constantly aware of the jaguars' presence in the dark.

-Al principio da miedo porque estoy rodeada de cosas que potencialmente me pueden comer cada día.

Caminas en la playa y sabes que están ahí.

Sabes que te están observando.

Te están observando.

Y no va a pasar nada.

Simplemente tienes que ser consciente de lo que haces.

Seguramente no me voy a bañar por la noche o no me voy a tumbar en la playa a dormir.

[ Waves crashing ] Pero es algo como que te cambia la actitud, y es increíble.

Gracias, pequeña.

Mucha suerte.

[ Waves continue crashing ] ♪♪ -Carolina isn't the only one patrolling the night.

Amanda has caught wind of a late-night snack.

[ Jaguar growling softly ] ♪♪ ♪♪ It's easy pickings on Jaguar Beach... ♪♪ ♪♪ ♪♪ [ Insects chirping ] ...and from the size of her belly, it looks like Amanda is eating for two.

But Amanda won't be the only mom whose success is tied to the turtles.

♪♪ About a kilometer offshore, the frigatebird colony is noisier than usual.

[ Birds squawking ] Across their island outpost, hundreds of downy hatchlings begin to stir.

♪♪ The first-time mother awakens to her hungry and persistent chick.

♪♪ For their first five months, frigatebird chicks depend entirely on their mothers for food.

♪♪ ♪♪ Chicks that don't get fed... don't last long.

♪♪ ♪♪ Mom has to hunt... and fast.

But she knows exactly where to go.

[ Birds calling ] [ Waves crashing ] The last month and a half have been quiet on the beach -- since the end of the arribada.

♪♪ But today, something is different.

♪♪ The sand begins to shift.

♪♪ ♪♪ The beach erupts with new life.

♪♪ ♪♪ ♪♪ ♪♪ For the hatchlings, digging their way to the surface is just the beginning.

♪♪ ♪♪ ♪♪ It's a long way to the water... and there's a gauntlet to be run.

♪♪ For a creature only five centimeters long, almost everything is an obstacle.

♪♪ ♪♪ A fallen branch blocks the path.

♪♪ [ Waves crashing ] At last, she's on the open beach.

But here, the dangers multiply.

♪♪ ♪♪ The young frigatebird mother swoops in right on time.

♪♪ ♪♪ One by one, hatchlings are carried off into the sky.

♪♪ A spiny-tailed iguana launches an aggressive ground attack.

♪♪ ♪♪ Even the crustaceans close in.

Ghost crabs are surprisingly strong.

♪♪ Another hatchling looks destined for a similar fate.

♪♪ With a survivor's determination, she fends off the attack.

♪♪ She races for the ocean.

♪♪ One final close call... ♪♪ ...and then... the finish line.

[ Waves crashing ] She plunges into a salty marine world, where she'll spend years before returning to this beach.

♪♪ She'll swim out past the rocky retreat, where the frigatebird mom can now feed her chick a magnificent meal.

♪♪ Only one in a thousand of these baby turtles will survive to adulthood.

♪♪ But Luis believes these hatchlings got some surprising help from the forest predator that takes their mothers but safeguards their nests.

-En que durante varios años hubo un vacío de neonatos naciendo en las playas.

Y en este momento, con la presencia del jaguar en la playa, estos neonatos están logrando nacer, están llegando al agua, y con mucha suerte, en el futuro van a poder ser nuevos individuos que van a venir a la playa a poner sus huevos.

Lo que me permite a mí concluir es que en realidad la presencia del jaguar es positiva en este momento para las tortugas marinas.

-Luis's team has found that jaguars kill less than 1% of the beach's nesting mothers.

And by warding off threats to the eggs, the predator has become the protector.

[ Birds calling ] ♪♪ On the island, the frigatebird chicks continue to gorge on the hatchling bounty... ♪♪ ...and in the forest, Amanda is caught on camera doing something strange.

♪♪ She tears off bite-sized portions from her latest turtle catch.

♪♪ ♪♪ A few days later, Luis's cameras provide an adorable explanation.

♪♪ ♪♪ Amanda with her curious new cubs.

♪♪ For the next two years, Amanda will teach her cubs how to survive... ♪♪ ...and guide them through the dry forest that helped bring her species back to this special beach.

♪♪ The rebirth of Santa Rosa's forest and the resurrection of its magnificent top predator has restored an ancient relationship.

♪♪ ♪♪ The renewed partnership has healed the connection between vastly different worlds... ♪♪ ...from the forest... to the air... to the deep ocean... [ Waves crashing ] ...to the beach where the lives of all their inhabitants intertwine... ♪♪ ...where two creatures reunite as they were for thousands of years... predator, prey -- unlikely allies in each other's survival... ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ -To learn more about what you've seen on this "Nature" program, visit PBS.org.

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