[police siren wails] NARRATOR: Cities.

Fast.

Loud.

And busy.

Home to more than half the world's human population... and we're not alone.

♪ An astonishing array of animals have moved in.

Like us, they're looking for the best places to eat.... make a home... and raise a family.

Against all odds... the wild world... is making it big in the city.

For some..... the newest and fastest growing habitat on the planet... Is a land of opportunity.

[♪♪♪] This unnatural world presents unique challenges.

But for those able to adapt and take advantage of the benefits of the city... the urban jungle is quickly becoming the new wild.

[police siren wails] ANNOUNCER: Wild Metropolis was made possible NARRATOR: As human cities expand, and areas around them become part of the urban landscape, many species have been pushed out of their native homes.

But some animals have been smart and moved into town.

Like here in central Thailand.

[traffic horns honking] In the shadow of Prang Sam Yot temple, these long tailed macaques are known as the Temple troop.

Here, they're treated like royalty, and even get fed every day.

Thanks to their popularity with their new city neighbors, they're given everything they need... and more.

They have inherited the best uptown address and have city life down pat.

They live pretty easy, and spend their days barely lifting a finger.

[♪♪♪] Born downtown, this young male is part of a gang some locals call the Mafia troop.

Life for them, on the other hand, isn't so easy.

Living on their street smarts, they have to work a whole lot harder than the temple troop to get their cut of the food here.

[train rattles] But as established residents, the Mafia troop knows the best spots in town to grab a bite.

[whistle] For them it's all about timing.

[whistle] Knowing when to stop, and when to go.

[♪♪♪] The Mafia troop youngsters learn the rules of the street by example, and they have no shortage of role models.

And while they've figured out how to take what they need from their human neighbors without asking, they've also learned that some will open their doors to them.

[woman speaking] Suthip Tantiwong lives and works in the centre of Lopburi.

[Suthip speaking] [Suthip speaking] [♪♪♪] NARRATOR: Like all long tailed macaques, the street savvy mafia troop are curious by nature.

And while the temple troop takes time out for mutual grooming, the mafia troop is always on the move.

They spend their time exploring the neighborhood.

With every new experience there's something new to discover.

[screeching] And in Lopburi they're finding everything they need is on tap.

Just down the block, some members of the temple troop are enjoying their life of luxury.

[screeching] With all their needs taken care of they're living it up in the city and don't give a second thought to their would-be rivals, the mafia troop.

And they have all of this without even leaving the comfort of their backyard.

[♪♪♪] [screeching] Lopburi's city-savvy long tailed macaques have successfully swapped the forested jungle for a concrete one.

[♪♪♪] [spray can hissing] They've got city living down.

They've figured out everything they need to survive here -- the best places to eat and drink, and the best places to live.

It's a recipe for success.

And with their ability to get along with us as neighbors they aren't just surviving, they're thriving.

In Lopburi 1,200 of them live side-by-side and lead a far more peaceful existence than rival troops in the forests of South East Asia.

[spray can hissing] And like them many species are discovering that city life means making the most of what they can find.

Of course, one thing every city has... [♪♪♪] is great places to eat.

And knowing the best joints to grab a bite is a number one priority.

With eight and a half million people living in New York, there's no shortage of places to eat.

[♪♪♪] Thousands of trucks deliver food into town every day to be sold at supermarkets.

or one of its 24,000 restaurants.

This is America's hungriest city.

And it's also one of its most wasteful.

New Yorkers throw away over a million tons of food every year.

But for one urban veteran in the Big Apple.

wasted food is opportunity.

Living right under our feet, "the pavement ant" is one of the oldest urban residents of all.

And like all long-time city folk, they know the best places to grab a bite to eat.

With poor eyesight, though, this scout relies on her antennae to track down her next meal within seconds of it hitting the ground.

Real fast food.

Hot dogs aren't pavement ants' natural diet, but New Yorkers through and through, they can't get enough of them.

And like all good city dwellers once they've found a good place to eat, they quickly spread the word.

Ants communicate using their antennae.

It's called "antennating" and relays all the information the colony needs to find the takeout.

And in no time the hot dog's swarming with other ants.

Barely noticed by most humans, they quietly provide a vital service to us, busily clearing wasted food from the streets of New York.

They consume the equivalent of 60,000 hot dogs a year... from Broadway alone.

By doing so they've become by far the biggest gang in New York.

With a population of 1.6 billion, they outnumber the city's human population by nearly 200 to 1.

And this colony is busy raising their next generation right under our warm sidewalks.

Taking advantage of warmth absorbed by the sidewalks to nurture precious larvae.

Like many established New Yorkers, this family's ancestors emigrated from Europe.

Where they've been living in human cities since Roman times.

And now they've found a home under these busy streets that suits them perfectly.

So often it's the old-timers that know the most about city living.

And in this ancient Spanish town, it's no different.

Life here hasn't changed much in a hundred years.

Its residents don't sweat the small stuff and live life in the slow lane.

[bell ringing] For centuries hundreds of white storks have been visiting Alfaro for a few months a year to nest and raise a family.

Some fly 4,000 miles to be here, migrating from Southern Africa.

Seen as a good omen they are welcomed into town by humans and partners clatter excitedly to greet each other each time they meet.

[beaks clattering rapidly] The town's terracotta rooftops provide them with a perfect summer home and their custom built nesting baskets take urban living to a whole new level.

Like every town, it's all about location, location, location and the storks are in strong competition for these prime nesting sites.

With a grueling return flight to prepare for, this chick and his siblings would normally have to quadruple their weight in just three months.

[♪♪♪] But these clever urban storks have discovered a local secret that means they can avoid the migration and hang on to their valuable real estate year round.

[♪♪♪] And that secret... is landfill.

[♪♪♪] Humans generate 10 times as much waste as we did a century ago.

But one man's trash... is another's treasure.

[♪♪♪] Picking through trash can be a risky business, but with so much at stake, the pros outweigh the cons.

[♪♪♪] And storks flock to landfills across Europe for their share of the 275 million tons of food we throw out of our cities every year.

[♪♪♪] They provide a daily picnic even in the coldest months.

And in the past three decades huge numbers of white storks have swapped their annual 8,000-mile round-trip journey for a permanent home in Spain, fueled by the food we throw away.

By changing their natural behavior these shrewd birds keep hold of their nest sites back in town.

It shows just how versatile urban wildlife can be as it adapts to our world in ways we could never have predicted.

[storks squawking] But of course, while food keeps many animals in our cities and towns, any really savvy city dweller knows... if you can find a waterfront home with a view of the park, that's the place to be.

[♪♪♪] Just like in South Australia's capital city.

Where the River Torrens feeds the largest urban park system in the country.

And the botanical gardens provide the perfect escape from the city for humans and animals alike.

[♪♪♪] Rainbow lorikeets like the easy life in the center of Adelaide so much, they've given up migrating and now live here permanently.

In 2010, following the worst drought in a century, a different wild crowd of 500 was forced out of their home in the Australian outback and joined the lorikeets.

And they liked it so much, they hung around.

[foxes screeching] With access to lifesaving water, their numbers grew and now 20,000 grey-headed flying foxes call Adelaide home, in what's known as a camp.

And they spend their days roosting high in these pine trees.

But of course, as good as it can be, life in the city's not always a picnic.

It's crowded.

And very noisy.

And in the summer, with the arrival of a series of music festivals, it gets even louder.

[♪♪♪] And that's not all.

In the past two decades South Australia has been getting hotter.

Temperatures here can top 100 degrees.

Everyone feels the heat.

Flying foxes are covered from ankle to nose in fur and they can't sweat.

So, if they overheat, they will die.

As they would in the South Australian bush, they find shade among the lower branches, and do their best to cool down.

Nocturnal by nature they'd normally stay in their camp during the day.

But dehydration is a real threat.

And desperate times call for desperate measures.

[♪♪♪] Leaving the trees they head to the lifeline that first drew them into the city: the River Torrens.

[♪♪♪] Today it's a sweltering 109 degrees.

Belly dipping provides instant relief for the bats.

It cools them down.

And gives them a chance to grab a welcome drink.

[foxes screeching] Back in the shade they drink any water remaining on their soaked fur.

[♪♪♪] As anyone who has lived through a hot city summer can appreciate, for the bats, nothing beats a day by the water.

Here in Adelaide it's helped this camp beat the rising summer temperatures.

And as the cooler evening approaches, they spread their wings again ready for a night searching for fruit and nectar.

And if, like the bats, you have all of the basics covered and have figured out how to live in the city, you can begin to focus on the things that really matter like starting a family.

Which for urban wildlife isn't as easy as it sounds.

But the best wild residents are versatile enough to adapt to whatever is thrown their way.

[birds chirping] One of Britain's rarest amphibians, great crested newts, are slow and vulnerable in the open.

But they can find safety even in the most unlikely of places.

Underwater, newts move with speed and are voracious predators.

But today this newt isn't on the hunt for food.

She's carrying around 250 fertilized eggs.

And needs somewhere safe to lay them.

A pliable surface will help protect them.

And she's made a surprising discovery.

Great crested newts evolved to lay their eggs within submerged leaves but after millions of years on the planet they've learned to be resourceful.

This plastic bag shouldn't be here.

But it's flexible and will make a perfect substitute for a leaf.

She makes a fold in the bag, and lays one egg in it.

Then gently wraps it up with her hind feet.

A sticky glue-like jelly around the egg will help keep it safe.

She squeezes the plastic together and holds it tight for long enough to allow the jelly to stick.

Over the next few weeks she'll lay around ten eggs like this every day, protecting each one in its own secure pouch.

And giving her offspring the best chance of making it.

It's an extraordinary adaptation to survive in a new and changing world.

Every city dweller must find a place to raise a family sooner or later.

And like all cities, Thailand's capital... is filled with hidden spots for wildlife to breed.

[♪♪♪] Reticulated pythons are the longest snakes on the planet.

They can grow up to 30 feet long and weigh more than 325 pounds.

But many of them still manage to live a secretive life in the heart of Bangkok.

Pythons are most active under the cover of darkness.

And by traveling at night they can move virtually undetected.

By filming under controlled conditions we can reveal what life's like for these city slickers.

They survive here by feeding on birds, rodents and other animals they can prey on.

But like every true wild resident, to make it in the city, they need more than just a square meal.

[police siren wails] They also need a safe place to start a family.

[traffic hums] [dog barks in distance] This residential garden is a haven from the busy city streets.

And when pythons want to nest, they seek out a concealed spot like this one.

[dog barking in distance] [car tires on gravel] Only once they feel safe and relaxed, will they begin to deposit their eggs.

This python is laying what's probably her first clutch.

Instinctively she wraps herself around them to regulate their temperature by expanding and contracting.

This is known as brooding.

[car drives by] A nurturing mother, she'll guard them with her life.

Pythons stay with their eggs for three months, and only leave them when they're ready to hatch.

But when eventually that time comes, the new arrivals will be on their own, primed to catch and eat what they need to survive.

Reticulated pythons have been residents in this area since long before the city was established.

With plenty of food and hidden places to nest, thousands of them are still at home here, even though pavement now covers the wetlands that Bangkok stands on.

[traffic hums] No matter which city wildlife is born into, growing up on the streets, it faces a whole set of challenges.

[♪♪♪] [squeaking] In the center of Singapore, these smooth coated otter pups are the newest kids on the block.

[squeaking] And they're about to learn what it takes to live in the big city.

[squeaking] In the natural world, this otter family would move their den if they thought there was a predator in the neighborhood.

They only have few natural enemies in the city but old habits die hard.

And at 10 weeks the pups are strong enough to make their first home move.

[squeaking] They'll learn everything they need to know about life on these streets from their parents.

Partners for life, they've learned the importance of sticking together.

Something this family will need to do if they're to make it safely across town.

[camera clicks] [squeaking] And only a few feet in... they hit their first obstacle.

It's a walk in the park for a seasoned citizen.

[squeaking] Most pups get the hang of it quickly.

But there's always one!

The unknown is a little daunting.

And reliant on his parents at least until his first birthday, this little guy can't afford to get left behind.

Lucky for him, Singapore is packed with waterways.

And for a naturally semi-aquatic otter, they're the perfect way to navigate this urban landscape.

[traffic hums] Six hundred miles of canals and rivers criss-cross the city.

The pups have only recently learned to swim.

And just over a mile into their journey, they are running on empty.

But for otters, Singapore's clean channels are far more than just convenient highways.

They need to eat nearly a quarter of their body weight in fish every day.

The young pups can't catch their own yet.

But with siblings who can, they just need to work out who's reluctant to share... and who could be persuaded.

They need to keep their strength up, because when you live in the city you never know who or what you might run into.

[screeching] [dog barking] But as they would in the natural world, these urban otters work together.

And as a gang they can overcome just about anything.

[dog barking] Like so many city residents, the older generation of Singapore's otters have life on the streets all figured out.

The urban world is their oyster.

In fact their family is doing so well, it's three times the size of the average otter family outside the city.

And on their way to a new home, they're passing down their street smarts to a new generation.

So when the pups are old enough to live on their own, they'll have everything they need to make it big in the city.

In spite of being completely man-made, our cities provide many of the same things animals look for in nature.

Urban parks imitate jungles and grasslands, with predators like jackals taking up residency and raising their young.

Even sidewalks provide unlikely havens for animals like bark scorpions to breed.

And city buildings across the world mirror cliff tops and have seen peregrine falcons move in to hunt.

But above all the one thing that all successful wild residents have in common is their ability to live alongside us.

Because in the confines of cities and towns like this one in Serbia, it pays to get along with your neighbors, and to have a little understanding and mutual respect.

This long eared owl has found a place to roost in Kikinda's town square.

And she's not alone.

A large group have gathered in what's called an owl parliament.

They find shelter here when temperatures drop.

Dense evergreen trees protect them from the wind and help them they stay well hidden from predators.

[children laughing] But for a shy sensitive animal that needs to rest in the day, the secret to success is the ability to cohabitate with us.

[indistinct chatter] They've learned to tolerate the hustle and bustle of urban life and more importantly the townsfolk are learning to respect the owls too.

[man speaking] NARRATOR: It's more than just neighborly courtesy though.

These owls wouldn't be here in these numbers if it weren't for us.

They flocked to Kikinda seeking refuge after the devastating Balkan wars in the 1990s.

Miroslav Gruje lived through the conflict too.

[Miroslav speaking in Serbian] NARRATOR: With the fuel supply cut off, forests across Serbia were chopped down for firewood.

Over 90% of the trees in the area were cleared, leaving the owls with nowhere to roost through the winter.

So they moved into town.

And Miroslav believes the owls have helped to transform Kikinda.

[Miroslav speaking in Serbian] NARRATOR: The owls have found shelter in town and are thriving.

And they've brought hope and light to the people here in the middle of winter.

[Miroslav speaking in Serbian] NARRATOR: It's common to find owls roosting in small groups.

But Kikinda's town square now hosts more than 750 of them in what is by far the largest long-eared owl roost in the world.

And it's estimated that 40,000 long eared owls now live in towns across Serbia.

Throughout winter the only time they leave their urban roost is to hunt in the nearby fields.

[traffic hums] Like the owls, a growing number of animals are moving into our towns and cities to take advantage of the opportunities they have to offer.

But ultimately city life is about co-existence.

And what's perhaps the most surprising are the relationships wildlife is striking up with other city folks.

[♪♪♪] No matter how different they seem to be.

[♪♪♪] Built on the banks of the Tocatins River in the Brazilian Amazon, the city of Mocajuba is growing fast.

On the edge of town a small group of fishermen have forged a very special partnership with some of the neighborhood's most established residents: river dolphins.

[♪♪♪] This species was only identified in 2012, the first such discovery in nearly 100 years.

They can grow over eight feet long and weigh more than 440 pounds.

Unlike most marine dolphins, their bodies are extremely flexible, enabling them to maneuver through some of the Amazon's most tangled tributaries in pursuit of fish.

River dolphins are normally shy, but this pod in Mocajuba has struck up a surprising deal with a local family.

Brasse Silva and his son Osvaldo have fished this stretch of river for decades and in recent years the river dolphins have joined the family business.

Brasse and Osvaldo give the dolphins an incentive to stay nearby.

And their very presence in the vicinity helps scare fish into these intricate wooden traps.

[Brasse speaking in Portuguese] NARRATOR: Like all of the best partnerships, they have an equal share in the business.

[Brasse speaking in Portuguese] NARRATOR: And because the dolphins get an easy meal they keep coming back for more.

[Brasse speaking in Portuguese] NARRATOR: It's a win-win situation.

[♪♪♪] River dolphins have evolved in the Amazon over 15 million years.

And today they are adapting to the fastest change this environment has ever seen.

[♪♪♪] But there's a deeper twist to this dolphin tale and the remarkable relationship they've built with their city-living neighbors.

Every single day the dolphins head to Mocajuba.

Whether there are fish on the menu or not.

It appears that one of the main reasons they come... is to play.

These powerful predators could easily hurt the kids, but they never do -- no matter what.

[♪♪♪] And the kids have grown up with dolphins as friends and will always look out for them.

The bond they've formed with these neighbors seems unbreakable.

And while Amazon river dolphins elsewhere are known to interact with humans, this behavior with no guarantee of food is unique to the Mocajuba dolphins.

Which perhaps makes them the most remarkable of all dwellers in the wild metropolis.

[♪♪♪] Most of us imagine cities to be concrete jungles.

Devoid of nature.

But for animals who are smart enough they are just a new habitat filled with new opportunities.

With similar needs to us, if they play their cards right, animals can find everything they need to survive in the city.

[squeaking] Food... water.... a home... and a safe place to raise a family.

And when wildlife can figure out how to live alongside us as neighbors, and even get a foothold in the city, the pay-off can be huge.

For them... and for us.

[chirping] Next time...

The world's wildlife is on the move.

[water splashing] Pioneering new migrations and facing new dangers.

Traveling in and out of our cities in search of their pot of gold.

[traffic hums] As the newest commuters into the wild metropolis.

[♪♪♪] 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.

[♪♪♪]