[police siren wails] NARRATOR: Cities.

Busy.

Loud.

And expanding fast.

For people and wildlife this is valuable real estate.

[♪♪♪] Animals that lived here before us are striving to find their place.

Using their brains... and bravado.

It's not easy.

But against all odds some wild survivors are making it big in the city.

For them the newest and fastest growing habitat on the planet is full of opportunities.

It's an unnatural world with unique challenges.

But for those able to adapt and take advantage of what cities have to offer, the urban jungle is quickly becoming... the new wild.

[police siren wails in distance] [car horn honks] NARRATOR: Over the last 30 years the world's urban areas have almost tripled in size, changing at a rate wildlife has never experienced before.

Some animals have adapted to urban life with surprising ease and made cities their home.

Others have found that by keeping one foot in the wild and commuting into town, they can have the best of both worlds.

[ducks squawking] But there is another group with the most surprising stories of all.

[bird cawing] Animals that lived on the land before we claimed it to build cities.

Today, they find themselves fighting for their place in a place that once belonged to them.

These are the wild survivors.

[police siren wails in distance] [birds squawking] Costa Rica.

A tropical tourist hotspot famed for its incredible wildlife encounters.

And this Pacific coastal town is home to some of the most intelligent monkeys in the world.

But the white faced capuchin monkeys here are in a perilous position.

Even though they've lived here for thousands of years, long before man came along, they are now struggling to hold onto their home.

Besides us, white faced capuchins have the largest brain-to-body ratio of any primate.

Being highly territorial, the wealth of tasty and exotic goodies tourists bring to the beach... makes it a hot property worth defending from other capuchins.

Around 20 strong, this is an average sized troop.

And this grizzled alpha male is in charge.

He lost his arm fighting to hold onto his territory.

His troop defends the tourist beach like they would a fruiting tree in the forest.

Because there are other capuchins that want a piece of the action.

[♪♪♪] And they will come to try their luck.

A tourist discarded coconut punch is the focus of this raid.

But the beach troupe are not going to take this sitting down.

[screeching] It's not long before the boss realizes what's going on.

[♪♪♪] [screeching] Faced with the full force of the gang, the invaders retreat.

The beach troop have done well to hold onto their territory.

Because if they use their intelligence to make the most of the area, there's more to be gained than a few measly leftovers.

[♪♪♪] [capuchin screeching] They've learned to play the naive tourists... [camera clicks] to get their hands on a seemingly never-ending supply of food.

And they've discovered there's more than one way to do it.

There's the sweet and innocent approach.

The hungry drifter... And the brazen and bold.

But these are not natural behaviors.

They should have an innate fear of humans.

But in fact the alpha male has no qualms about showing who's in charge.

And the more the capuchins expect food, the more aggressively they'll act to get it.

[screeching] By continuing to feed them humans are only fueling this behavior.

The capuchins will stop at nothing to get what they want.

and that could end badly for them.

They wait patiently for people to leave their belongings on the beach... before moving in to steal any food.

Capuchins are one of the only primates known to use tools.

So opening unattended luggage is no problem.

But their thievery and bullying tactics are making them unpopular.

[screeching] And right now, they face an uncertain future.

Unless the tourists change their habits these capuchins could start to be controlled like pests.

As our cities expand, finding a solution to situations like this is essential.

[♪♪♪] [capuchin chirping] The capuchins have taught us that we need to be more aware of how we interact with the wildlife with whom we share our world.

The urban environment can work for humans and animals.

But at the moment, cities support just 20% of the wildlife that lived on the land before they were built.

If we protect space for nature in the modern world we can help to ensure its survival.

[jet engine roars] It has never been more important.

[♪♪♪] It's predicted that by the middle of the century, 50% of the world's species will be in decline.

And that's in part because the land around cities is being cultivated to feed our ever growing populations.

Nowhere is the scale of the problem more obvious than in Sri Lanka.

Where forests are fast being replaced with crops.

Putting people in direct conflict with the largest land mammal of all, elephants.

As their jungle disappears and is farmed to feed us they've had to find new ways to get enough to eat.

[♪♪♪] [fire crackling] Under the cover of darkness the elephants head into town for some takeout, and a fight.

The local inhabitants guard their livelihood.

[indistinct shouting] Armed with lights, firecrackers, and flares, hoping to scare the invaders away.

[indistinct shouting] It's a risky strategy for the elephants... but hunger drives them on.

For both sides, it's a fight for survival.

Each year this conflict claims the lives of over 200 elephants and 80 people.

[explosion] Explosions across the region mark the start of the nightly battle Between the two sides who both claim this fertile land.

[♪♪♪] [explosion] [elephant trumpets] [explosions continue] [lighter clicks] [explosion] The elephants retreat, but to grow up to ten feet tall and weigh five tons they need to eat over 300 pounds a day.

They'll be back for more.

[explosion] [♪♪♪] With the encounters taking their toll on both sides a ceasefire is well overdue.

And the community is developing ways to keep the peace.

Farmers have found that planting a barrier of fruit trees around their crops can help.

Because elephants have the best sense of smell in the animal kingdom, and find the smell of citrus repellent.

The trees act as a sustainable buffer that encourages the elephants to feed back in the forests.

Electric fences that surround some of the villages help too.

But the elephant encounters that happen outside the fences are the most dangerous.

And for some kids this road through a notorious elephant corridor is the only way to school.

It's a potentially deadly commute on foot.

But they've found a simple solution.

An elephant school bus, funded especially to keep these kids out of harm's way.

Each morning the bus picks up kids from the surrounding area and drives them safely to school.

A journey of fear... is now one of joy and wonder.

[♪♪♪] [indistinct chattering] Elephants don't perceive large vehicles as a threat in the same way they would a person on foot - making for a peaceful passage.

[♪♪♪] These Sri Lankan communities are finding a way to live alongside the largest of animals.

But across the world elephants are losing their natural homes and food sources, and being poached for their ivory.

The global population has shrunk by a shocking 95% in the last century.

It's a crisis desperately in need of solutions.

Peaceful coexistence with large and dangerous animals is possible.

[splashing] On the east coast of the United States, luxury golf resorts have been built on prime alligator habitats.

[♪♪♪] And on Kiawah Island in South Carolina, the water hazards, rough and rolling greens, are a paradise for golfers... and gators alike.

That's because each species knows its place here.

The ponds belong to the gators.

And the fairways are reserved for golfers.

But each spring as males compete for the best territory and the best females, the boundaries become blurred.

This huge 13-ft. male guards his network of ponds and channels.

And he protects his love interest too... whether she's interested or not.

But there's no rush.

New science shows that gators can actually mate for life.

[gator growling] He warns the smaller males off her by broadcasting his dominance with an infrasonic, then bellowing call... [gator growling] that can be heard from three miles away.

[gators growling] [gator growling] [♪♪♪] Happy he won't be interrupted, he makes his move.

But she needs some wooing.

[♪♪♪] Turning on his charms he rests his head on her back and blows her romantic bubbles.

[gurgling] During a brief moment underwater the pair mate.

[♪♪♪] With this female spoken for, the youngsters walk the course in search of their own territory.

[♪♪♪] But all the best spots are taken.

[splashing] Following and posturing is usually enough to end the disputes... before they really start.

[♪♪♪] With a bite three times more powerful than a lion's, it's better to retreat than risk injury.

Even though it is built on alligator territory, this high-end human playground provides for both people and wildlife.

[jet engine roars] Striking the right balance with animals we naturally fear can be difficult, but cities will continue to attract uninvited wild guests.

Because sometimes the city can offer them what they need to survive.

And those animals small enough to take advantage of these opportunities unnoticed... can make it big.

[♪♪♪] Once a tiny desert resort this city is built where few animals or people ever lived.

Everything you see has been brought here by humans.

Hidden in plain sight, one small but deadly survivor is thriving in this shiny, new desert oasis: the bark scorpion.

[♪♪♪] These tiny arachnids are just a few inches long but are the most venomous scorpions in North America.

The vast, open desert is their natural home.

But despite the city being built here, they have flourished.

In the summer, when males search for a partner, action on the Strip gets pretty hot.

[indistinct chatter] Bark scorpions have 12 eyes, but their vision is poor and they can only see shades of light and dark.

So males follow the scent of a potential mate using specialized sensory organs on their bellies called pectines.

But finding her is only half the battle.

Locking pincers she tests his strength... and suitability as a father.

He needs to be careful.

One false move and she'll have him for dinner.

She will carry her fertilized eggs for up to a year, and if times get hard, she'll re-absorb them.

But in this city of excess, that's unlikely.

[♪♪♪] There's plenty of food around.

As ambush predators, bark scorpions feed on insects like cockroaches and crickets, providing a useful pest control service.

[♪♪♪] She stuns her captive with a potent neurotoxin, and dissolves parts of the body with enzymes before eating it.

When the female is ready she gives birth to up to 30 helpless young that she will carry on her back until they are old enough to survive alone.

In her six-year lifespan she could produce 150 babies... fueling a population boom.

Scorpions may not be welcome, but being one of the only lifeforms able to survive at nuclear test sites, they are likely here to stay.

And because cities can offer everything an animal needs to survive - food, shelter and somewhere to raise a family - some tenacious creatures find a way to live between the cracks of the urban world... no matter what we throw at them.

One notorious survivor has been so successful at avoiding our attempts to banish them, that it is now common in nearly every human settlement in the world.

The brown rat.

In fact our cities are so full of food, water and accommodation that they have left the wild altogether, and are now only found living alongside us.

Worldwide they outnumber humans by billions.

And like the scorpions in Vegas, it's their extraordinary ability to reproduce that's the biggest secret to their success.

By filming this female and her nest under controlled conditions we can reveal why.

[rats squeaking] This litter is just ten days old and about to open their eyes.

But in less than two months time the young females will be able to have babies of their own.

[rats squeaking] And from then on could have a litter of eleven every three weeks.

That's up to 3,000 descendants a year each.

[♪♪♪] They explore the world around them with a nose that will eventually be more sensitive than a bloodhound's.

For now, though, mom wants to keep them safe.

[squeaking] [indistinct chatter] But just a few weeks later the young females are on the move, looking to start their own family.

It's a dangerous time.

More than 50% of rats die within 10 days of leaving the nest.

So they are naturally wary of anything unfamiliar.

[♪♪♪] But few things stand in their way.

They can squeeze through a gap a quarter of their size.

Hollow walls in modern buildings provide perfect hidden highways.

With flexible feet and fine claws, rats can climb around inside them... even when upside-down.

[traffic hums] The outside world presents different challenges.

It's the rat's innate skills that have made them such an urban success story.

As they find their way around, rats make a mental map of new surroundings.

And with soft pads on their feet, they can grip even smooth surfaces.

Rats are one of the few mammals who are able to plan complex routes to reach a goal.

[♪♪♪] [dog barks] Expert tightrope walkers, they use their flexible tails as a counterbalance.

[squeaking] It's risky... but a highly sensitive nose confirms it's a risk worth taking.

With powerful back legs she can leap more than four times her body length.

Ever wary... she's out of there at the first hint of danger.

And because of her strength and flexibility, she could survive a fall of over seven feet.

[♪♪♪] In the shadows rats have all the skills they need to ensure the survival of their species... right under the noses of their age old enemy.

[rat squeaking] No matter how extraordinary an animal is there are some that may never be welcome.

[traffic hums] However, life in the city can be more accommodating for survivors who have a better public image.

[bird caws] Built on prime marshlands the capital of the Netherlands is synonymous with a bird that has lived in these waterways since long before the city was built.

The grey heron.

They've eked out a living and survived here, feeding on their natural diet of fish and frogs.

[♪♪♪] But in extra cold winters the city's 100 miles of waterways can freeze solid, locking their food out of reach.

Some have learned that if they get their timing right there are still places in town to get a good meal.

They head to the fish market just before it closes at 5:00 pm.

And they wait.

[birds cawing in distance] The bold come down looking for scraps even before the market-goers have left.

But there are slim pickings this early.

[bicycle bell rings] As darkness descends so do the rest of the herons.

[car horn honks] Dancing between carts and vans they fight for the leftovers.

[birds cawing] Feeding after dark is highly unusual behavior.

Herons are hardwired to roost at night to avoid predators.

But the fish market provides them a vital lifeline in the cold, hard winter.

It's a race to clean up as fast as possible, head to head with their modern inner-city rival: street sweepers.

[squawking] By adapting to the changing urban world... [squawking] the herons have secured their future in the heart of town.

[truck beeping] [♪♪♪] And because they are established in the city some have even formed remarkable relationships with the locals.

In a sleepy suburb, one lucky heron has been welcomed with open arms.

Deany Diepbrink is preparing breakfast for her good friend, Kiri.

[Deany speaking] DEANY: Kiri!

[clicking with tongue] DEANY: Kiri!

[clicking with tongue] Kiri!

[♪♪♪] [Deany speaking] It's beautiful.

It's beautiful.

NARRATOR: Deany and Kiri the heron show that if we welcome wildlife into our lives, it can benefit both animals and people.

It's a winning strategy that has also worked on a far larger scale.

It's even helped bring one of Florida's state mascots back from the brink of extinction.

The town of Crystal River is famous for the glass-like spring-fed rivers that originate in the heart of town.

But its biggest tourist attraction by far... are its manatees.

A native of Florida's wetlands for thousands of years, these huge vegetarians, also known as sea cows, can grow to 13 feet in length and weigh up to a ton and a half.

Despite their size they do not have much insulating body fat, so when the sea temperature drops too low, they can develop cold stress, a condition similar to frostbite, which can be fatal.

So in the winter they head into town, where a warm welcome awaits.

Calves rely on their mothers until they are two years old, so they make the journey side by side.

Swimming an average of five miles an hour they cruise past waterfront condos and jetties on the way.

And when hungry, calves nurse from their mothers.

Every three to five minutes they come to the surface to breathe.

When they reach Three Sisters Spring, they can relax.

Here 10 million gallons of crystal clear water pour out of the ground each day, at a constant 72 degrees.

The perfect temperature for manatees to avoid cold stress.

[heavy breathing] Here, mom and baby can slow down and save energy.

When it's really cold over 500 Manatees pack themselves into the toasty springs.

That's almost 5% of the world's population.

But 30 years ago, the story was very different.

Pollution and severe injuries from boat traffic had caused their population to all but collapse.

Prompting a large scale initiative by the local community to protect them.

Today, over 100 volunteer manatee guardians police exclusion zones.

[♪♪♪] [camera clicks] [heavy breathing] Strict speed limits control boat traffic and visitors are educated on how to behave around manatees.

ALYSSA SYNC: What we normally do is get up three to six feet away from them then we stop.

Here's where we passively observe them.

When in doubt, just remember to float, it'll be perfectly OK!

NARRATOR: The program has been an overwhelming success.

And in 2017 manatees were taken off the endangered species list.

Manatee tourism attracts up to 250,000 tourists a year, generating an income of more than 30 million dollars.

It's no secret that we need to protect nature.

Only now are we starting to realize that our towns and cities have a role to play in this.

Perhaps most surprising is that it can be a two-way street.

In Indonesia, one of the fastest birds in the world has developed such a productive relationship with people that they've had an exclusive community built just for them.

[♪♪♪] Swiftlets.

These birds are traditionally found within deep cave systems but have been invited into people's homes and specially built swiftlet hotels.

[birds chirping] This male is building his nest using extra thick and sticky saliva he produces in a gland under his tongue.

Over 40 days he adds layer upon layer until his tiny cup-shaped nest is finished.

Pairs have up to three clutches of one to two chicks a year.

Once they've fledged the hotel owners move in and harvest the nests.

Which are the main ingredient in a Chinese delicacy: bird's nest soup.

[birds chirping] [♪♪♪] The birds are doing so well that they may soon be classified as an entirely new sub-species - the house swiftlet, evolved to live within our four walls.

Everyone wins.

The swiftlets are guaranteed shelter and safety.

And the farmers get $1000 a pound for their nests.

Completely changing the lives of the people here like Daud Bapak.

[Daud speaking] NARRATOR: The more we learn, the clearer it becomes - managed in the right way, having wild neighbors can help ensure a secure future for both of us.

[helicopter whirs] And nowhere is this more evident than on San Clemente island off the coast of California.

[rhythmic marching beat] Where a wild guardian angel and the military have formed an unlikely reliance on each other.

MAN: Left face!

NARRATOR: This tiny speck in the Pacific Ocean is just four miles wide and 21 miles long... and a highly sensitive US naval warfare facility.

It's the only place in the world the US Navy is authorized to practice sea-to-land bombardment.

[explosion] But they aren't the only deadly force on the island.

A little known predator is watching their every move.

[crow caws] The San Clemente fox is the island's largest carnivore.

But at the size of a domestic cat, it's one of the smallest canine species in the world.

[helicopter whirs] With endless drills and exercises, the barren south end of the island is uninhabitable.

[explosion] But these foxes thrive in the north... [helicopter whirs] living amongst Navy personnel and close to the airstrip.

[jet engine hums] It's the closest thing to hustle and bustle in this corner of the Pacific.

This vixen Daisy has a den full of cubs right by the busy port.

It's the perfect spot for her to raise a family.

[truck beeping] Because foxes have access to all areas of the busy high-security base.

[cubs chirping] But Daisy has her work cut out for her.

Normally she has just two cubs a year.

This season she has three.

[cubs chirping] The cubs will learn everything they need to survive here from their mother.

She's teaching them to eat a wide range of foods - from lizards and small mammals to insects, even birds eggs.

Climbing trees doesn't come easy to a five-week-old cub.

[cub whimpers] But the rewards are worth it.

San Clemente foxes don't exist anywhere else in the world and 15 years ago the species was listed as critically endangered.

The Navy was warned, that if the fox numbers dropped any further they'd have to leave the island to allow them to recover.

So the military now invests seven million dollars a year into the protection of the island's wildlife.

[truck beeping] An island-wide speed limit has been imposed, and reminders to be respectful of their wild neighbors have been posted.

Let's get a collar on her.

NARRATOR: They have even put in place a team of scientists that run a fox awareness program to track and monitor the population.

[truck beeping] The foxes are now off the endangered species list.

But today, the Navy is not just looking out for them because they have to.

There's real affection here for these tiny predators.

Protecting this wild population safeguards the Navy's presence on the island.

It's a relationship that also shows the military's warm and caring side.

[traffic hums] But as urban areas expand... [bear growls] more and more wildlife will need our help if they're to have a future.

[owl chirps] [♪♪♪] And where we have given it a chance, there is hope.

Forty years ago New York had some of the most polluted waterways in the world.

And species that had survived there for thousands of years had all but vanished.

But efforts to clean them up have paid dividends.

And recently scientists like Howard Rosenbaum have witnessed an amazing recovery.

ROSENBAUM: Right here in New York we're seeing the benefits of five decades of protection and we're seeing the fish stocks recover from depleted numbers.

NARRATOR: Waders and fishing birds are flourishing in what was once empty marshlands.

Pods of dolphins hundreds strong can now be found in sight of the city.

[air spurting] But the biggest surprise is the return of one of the Atlantic's giants: the humpback whale.

[air spurts] ROSENBAUM: For quite some time it was considered probably the sighting of a lifetime.

I mean, just to think about the fact that you could be strolling on the beach and see a humpback.

People are not used to having humpbacks in and around New York.

[air spurts] NARRATOR: The fish they prey on is now so abundant that New York's coast has become a perfect summer stopover for the whales.

[♪♪♪] ROSENBAUM: We see healthy animals foraging here, feeding right close to our shores.

I mean, it's phenomenal.

[air spurts] We are at a critical point in history.

Our relationship with the planet is increasingly fragile.

We are consuming more than we ever have.

And while our population is booming, it's estimated that we've lost half of the world's wildlife in just 40 years.

But in our cities, the newest and fastest growing habitat on earth, we can make a difference.

Simply by giving nature the space and resources it needs.

Even for the biggest and most surprising of animals, the urban jungle can be a place of opportunity.

[♪♪♪] So what happens next is up to us.

[♪♪♪] [♪♪♪] ANNOUNCER: To order Wild Metropolis on DVD, visit ShopPBS.org or call 1-800-PLAY-PBS.

This program is also available on Amazon Prime video.

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