All language subtitles for BBC.Natural.World.2011.Animal.House.1080p.HDTV.x265.AAC.MVGroup.Forum.eng

I'm fascinated
by the glimpses we sometimes get

into an animal's hidden world.

Over the years, I've found
different ways to peer inside.

They say, if you want to understand
people, look in their houses.

I think the same may be true
for wildlife.

I've never been invited in

and, on occasions,
I've not been entirely welcome.

I think that was pretty clear.
Oh, dear!

Despite setbacks,
I've seen skilled builders...

I've discovered
squatters and burglars...

I've noticed interior decoration...

I've found storerooms
and air conditioning

and even en-suite bathrooms...

I've visited animal cities

and huge communities.

Wild homemakers
are special creatures,

more like us, trying to keep out
the wilder wildlife.

Peering into an animal's house
can tell you so much about them.

It's a window
into their private dramas

and the intimate stories
we rarely see.

Most of us are indoor creatures.

Houses have ended our wild days.

Yet, we forget that animals build
many more houses than we do.

And they've been doing it
for much longer.

We think we alone
invented building materials,

but animals have done so, as well.

Scaled up to our size, termite
mounds would be almost a mile high.

Animals have an eye for beauty

and so do we.

Our homes reveal a lot about us,

but this is the animals' story.

In North America lives probably
the most ambitious

animal builder in the world.

Up to a mile or so of river is taken
over by a single family of beavers.

Dams flood the landscape,
creating ponds

and canals that cover many acres.

At the centre is their lodge -

a defensive moat
surrounds a sturdy castle,

made of serious building materials.

A beaver can gnaw through a tree
in an hour or two.

He often stops halfway
and lets the wind do the rest.

His teeth are reinforced with iron,
which turns them orange.

The teeth wear down
a millimetre a day,

but grow ten times faster
than our fingernails.

Even metre lengths are too heavy
to drag over land,

but by flooding the area, the
beavers can easily move the logs.

Each dam needs about 50 tons
and can be hundreds of metres long.

Mud is used to seal any leaks.

Everything has to be ready
for winter.

Of the beaver's rural community,
most have left or are hidden,

housebound, at this time of year.

The only sign is a ripple of heat
from a chimney,

identifying the beavers' lodge.

Inside, special cameras
reveal new young,

born early, thanks to the protection
of metre-thick walls,

sealed with mud and straw.

It's been minus 20 outside
and still didn't freeze in here.

The chimney is open,
as now it gets too hot.

The only way in and out

is to swim underwater, but that
doesn't discourage a muskrat.

Voles, mice and insects
also find refuge here.

The lodge has lodgers.

We never saw the landlords
object to the muskrat,

which is more than can be said
for the cameras,

which they soon censored!

Outside, the itinerant
and the homeless

must wish they were somewhere
safe and warm.

WOLF HOWLS

Solid walls and underwater doors

are not the only ways
to try and keep the outside out.

Prairie dogs live in an underground
colony called a dog town,

which can stretch over the horizon.

The town is divided into coteries,
extended families,

living behind a volcano-shaped
front door,

and with an acre or so
of manicured lawn to provide food.

Prairie dogs themselves may
seem like fat vegetarian meerkats,

but they're actually squirrels...

that bark.

And they don't like visitors.

There's a father in charge,

several wives, and different
generations of youngsters.

Each family rarely goes beyond
their garden boundaries,

and they all work together
on their house.

Time is spent on home improvements
and household chores.

The raised entrances
are watchtowers,

but are also chimneys,
and draw air through the burrows.

The lower-level holes
are fresh air intakes.

Inside each family home
may be 30 metres of tunnelling

with many different rooms.

There are sleeping chambers,
where they spend most of the winter.

Some even have an adjacent
lavatory room.

There are storage rooms,
anti-flooding features,

and escape hatches.

It's warm in winter
and cool in summer.

It's an estate agent's dream.

The pups, at a few days old,
are tiny, bald and blind.

Their mother will stay with them
in a special nursery,

feeding them
and sorting out bedding.

Even at birth, prairie dogs
are clearly builders,

with shovel-shaped heads,
cylindrical bodies,

and digger's claws.

With so many corridors,

it's possible that one might lead
by mistake into a neighbour's house,

and the neighbours
could be burrowing owls.

In the dark,

the startled owls give a good
impersonation of a rattlesnake.

OWL HISSES MENACINGLY

The owls have young, too,

hatched in an abandoned part
of the prairie dog burrow.

They are, in effect,
harmless squatters.

The dog town is full of freeloaders.

Hares and snakes find homes
in this mixed neighbourhood.

Dangerous characters,
like black-footed ferrets

and swift foxes,
live in old burrows.

Overall, wildlife increases
wherever animals build homes,

whether the builders like it or not.

Maybe as a response,

prairie dogs have
a community police service.

Family members takes turns
watching out for predators.

A prairie dog calls "Eagle!".

Families for up to
half a mile around run for cover.

The whole neighbourhood benefits.

The prairie dogs even have different
calls for different predators.

"Coyote" sends them
down their burrows,

but calling "Badger"
needs a different response,

as badgers can dig,

so the dogs watch them nervously
from the surface.

Their calls may include
information on size,

direction and speed, even colour.

It's one of the most sophisticated
animal languages ever studied

and has arisen
in response to the predators

that are drawn to animal houses.

Living close to your neighbour
can provide some protection.

The problem is, it can also
attract more predators.

Southern carmine bee-eaters catch
the eye of a hungry fish eagle.

Predators have a major influence
on how houses are built.

Here, along the Luangwa River
in Africa,

sandy cliffs are one of
the few places out of reach

of eagles, lizards, and monkeys.

A bee-eater pair takes turns
digging the burrow

with their beaks and feet.

The centre of the colony is safer
from predators than the edge,

so the birds nest closely
together in the middle.

The result is evenly-spaced lines
of townhouses.

But, the denser the colony,

the more attention it gets.

The bee-eaters unite,
screaming at the intruder.

Noisy neighbours are a life-saver.

On every continent, animals converge
to build homes together.

A quarter of a million
Socotra cormorants

arrive on desert islands off Arabia

to build simple mounds in the sand
away from predators.

Some debris is favoured
for the nest, other bits rejected.

The bird next door
tries to steal from the collection.

The chicks, when they hatch,

must be protected from the
neighbours' lethal beaks,

so nests are built
just out of pecking range.

They end up building
near inch-perfect

geometric plots in their thousands.

But the greatest animal houses
in the world are caves.

3.5 million bats
live in this cave in Borneo.

Each evening, they leave
the safety of their home

to feed on insects
in the surrounding forest.

They gather outside the city gate
in a defensive whirlwind.

The swirling commuters
are running a gauntlet

of bat hawks and peregrine falcons.

The birds of prey grab anything
that tries to go it alone.

As the nightshift leaves home,

the dayshift is returning.

Cave swiftlets navigate into
dark caverns by echolocation,

like a bat,
almost the only birds to do so.

They make powerful clicks,

and listen to the sound
bouncing off the walls.

Male swiftlets
choose tiny high-rise ledges,

maybe 100 metres
above the cavern floor.

They share the space

with specialist spiders,

cave centipedes

and bats.

The bats have left a
stinking mountain of droppings

over 30 metres high.

It's the biggest indoor lavatory
in the world.

This is a cave with double
the population of Manhattan

and no plumbing.

And it's crawling with cockroaches.

The cockroaches
feed on the droppings,

and anything else
that falls to the floor.

The best ledges
have to be fought for,

and a male battles over
real estate in the pitch blackness.

Swallows and martins
normally use mud,

but the swiftlets
make their own walls.

It's a sort of gluey saliva,
which they attach to the rock,

and build up, layer by layer,
making a tiny egg-cup.

It can be weeks of painstaking work.

The saliva hardens

into one of the most extraordinary
animal houses in the world,

a crystal chalice.

The nests become as crowded
as closely-packed apartments.

Woven-in feathers darken the nests,

but single white eggs
glow in the lights.

For generations, this cave has been
one of the safest homes.

That is,
until a new predator found it.

Men are here

to collect a culinary delicacy
for the famous bird's nest soup.

The saliva is full of proteins
and minerals,

but apparently the nests
don't taste of anything.

The little homes are worth
thousands of dollars a basketful.

The legal trade alone
in bird's nest soup

is worth about
half a billion dollars.

Inevitably,
wild cave swiftlets are in decline.

Saliva is an extraordinary
building material,

but perhaps the most
remarkable of all is silk.

The coiled threads of protein
are famously strong and light...

..which is why
other animals steal them.

A bronzy hermit hummingbird
in Central America collects cobwebs.

With the silk threads, she weaves
a pocket, anchored under a leaf.

The leaf keeps out the rain,
and prying eyes.

Camouflage is all the defence
she needs.

A lethal trap has become
a different sort of home -

a cradle.

Baby hummingbirds grow up
suspended in silk

and fed on nectar.

The second-hand web can carry
the young and the parent birds,

though it was originally made
only to catch a fly.

Even ordinary building materials
can be transformed

by the skill of the builder.

A female red-rumped cacique
in South America

ties palm leaf strands
into loops and knots.

The mother caciques
choose the nest site,

build and bicker over space.

The architectural blueprint
is instinctive,

but she adapts and refines
the basic plan,

and her skill improves
with practice.

The foundations are made first,

then a loop,
the entrance to the nest.

The door is extended into a tube,

like a sock
about 40 centimetres long.

After up to three weeks' work,
a nest is finished at the bottom.

You can't leave your handiwork
for long,

or your older and cannier neighbours
try and pull it apart

and steal your building material.

The final nest is this shape
because there are egg thieves.

This is a Toco toucan.

The nest tube must be long enough

so that predators can't see
the chicks or reach the bottom.

Over the generations,
caciques have extended their nests

to keep the young safe.

The toucan is trying an attack
through the side of a nest.

They have an unlikely ally.

Casiques often nest
near bees and wasps.

The chicks are safe,

though the nest
seems to have acquired a new window.

It looks like the parent may have
to get materials for repair work.

Building supplies are so important

to some animals that, in places,
the materials themselves

have taken on a particular
significance.

Flightless cormorants
build their nests from seaweed.

On the shores of the Galapagos
Islands, there isn't much else.

It seems this is as much
about their relationship,

as building the nest.

They're like newlyweds
cooing over paint swatches.

Colour is important, and texture,

and the females
seem to weigh up each gift.

Occasional exotic offerings -
a living sea urchin,

or a new shade of seaweed -

are brought to the nest,
and sometimes rejected.

A gift that walks away is of no use.

And size
certainly doesn't impress her.

The drying seaweed means more
to the cormorants

than mere construction materials.

A nest becomes a special place,

to be defended
from curious visitors...

..and a perfect home for the eggs.

We don't know exactly what
they think or feel,

but some scientists
believe the effort

seems to draw them closer together.

The chick benefits
from the parents' commitment

to making the perfect home.

The ultimate example of an animal
that builds a palace

to win round a mate can be found
in the forests of New Guinea.

This metre-wide woven wigwam
is a seduction pad

and is all about show.

Carefully arranged flowers and fruits

are placed in piles
on manicured moss.

Smaller treasures are towards
the back,

to make the bower seem bigger,
a trick interior designers use.

Yet the male Vogelkop bowerbird
himself is modest, even drab.

It may take many years to become
a proficient enough

house builder to reach this stage.

If he sees a twig out of place,
he'll push it in or remove it.

His architectural eye is unique.

His rival neighbours each have
different colour schemes,

or floor designs or decorations.

This particular male is going
through a red phase.

The flowers are changed regularly

and the berries must be perfectly
arranged, even the right way up.

The floor is a challenge.

Roots grow through the moss
and have to be tackled.

What he can't remove,
he sweeps under the carpet.

A rival male is singing.

He must respond.

We see perhaps now why the bower
is the shape it is.

It's a concert platform and the
arch may help project his voice.

He ends with a little dance.

The audience has arrived.

She seems interested,
but he has disappeared.

It is crucial in bowerbird courtship
that he remains hidden.

His house has to coax her in.

Only when she is brought to
a state of ecstasy over his decor

does he dash out and try to mate.

It's not entirely successful. Maybe
she wasn't ready for his appearance.

Or maybe his flowers or his floor
weren't up to scratch.

It's most frustrating.

Perhaps he will tempt her back
and maybe next time,

the bower will be looking
at its best.

Home decoration can, occasionally,

be about more than impressing
the perfect partner.

The burrowing owls in
prairie dog town have a strange take

on suitable suburban decor.

Their landlords, the prairie dogs,

would not approve
of this innovation.

What burrowing owls like
is what the buffalo leave behind.

They collect dung.

The owl places the dung carefully
around his front door.

The burrowing owl chicks don't seem
impressed by the collection

of poop on the stoop.

This is not how most wise animals
treat their own doorsteps.

In fact, this extraordinary
bit of decoration

is a trap for beetles,
particularly dung beetles.

The beetles find dung by smell.

It is, to them, building material
and food, rolled into one.

Tons of dung are trundled away.

The dung ball,
with an egg inside, is buried.

A warm and delicious home,
at least for a dung beetle larva.

Birds and mammals almost never
turn their homes into traps,

as spiders do.

Human beings and burrowing owls
are said to be the only examples.

A chick takes some dung
down the burrow.

Maybe it's learning
the connection with food.

It's a step in the right direction.

The owl mother doesn't agree and
turns it into a lesson on housework.

Homes are hard work and there's
a lot for young animals to learn.

Home making requires
a sense of place,

as well as working out how to
get along in a community.

The trap seems to have worked.

Food is always critical,

so many animal builders put a larder
at the heart of their homes.

The beavers' system of canals
and ponds is a massive cold store.

Beavers eat bark and leaves

and stocking the larder is a job
that takes months.

The beavers wedge
the branches down in the mud.

Even stored underwater, a potential
burglar spots the stockpile.

But the moose is soon told that
this store is private property.

A few tail-slaps
and the intruder gets the message.

A house is of little use
if there's no food.

Winter in Outer Mongolia
would be hard for a hamster,

without a well-stocked store room.

Down the burrow,
there are several rooms.

In the bedroom,
the young are kept warm in straw

and fed by their mother.

Next door is the larder.

All autumn, they gathered seeds
in their cheek pouches

and brought them down here.

Thanks to the seeds
staying safe and dry,

the hamsters can start a family
while it's still barren outside.

Our own earliest buildings
may have been grain stores.

Protecting food for winter

enables house builders
to move into colder areas

where the homeless
could never survive.

Some homes go a stage further.

They have a living larder.

A mole's network of dark passages

can be extended at up to
two metres an hour

and provide the mole's food.

Earthworms burrow through
the walls by accident

and the star nosed mole has special
worm-detecting feelers on its nose.

This housebound animal
has a curious reputation

as the fastest eater on record.

An earthworm can disappear
in a quarter of a second.

Not everyone can build a house
where your food literally

drops in for dinner -
and not everyone likes earthworms.

In China, bamboo is
one of the fastest growing plants,

but I have heard of it occasionally
growing back into the ground.

Under the bamboo is a quarter
of a mile of tunnelling,

built over several years
by bamboo rats.

The tunnels follow the roots

which run along the ceiling,
like service pipes.

She checks the bamboo by smell.

If the roots put out a new shoot,
she can sense the fresh growth

and when it's the right length,
she harvests it.

The house has become a farm.

She has the same iron-coated teeth
as the beavers.

Both are rodents, which are the vast
majority of mammal house builders.

Her young have never been out.

She's blocked the exits.

The outside world
might as well not exist.

The little ones seem
determined to explore,

but may get lost
in the network of tunnels.

So, she literally drags them

around the labyrinth of her
underground bamboo farm.

American beavers build canals
to carry trees

and Chinese bamboo rats harvest
bamboo underground,

but in South America,

another animal takes the idea
of a home farm a stage further.

Leaf and grass-cutter ants

take about 10% of the forest's growth
underground, to fungus farms.

The white fungus grows on
the chopped-up leaves

and is pretty much all the ants eat

The fungus farm generates heat
and carbon dioxide.

Pipes lead to a large mound
above the ground.

The chimneys are like
the raised prairie dog burrows,

drawing the air through the nest.

Nobody knew how big grass-cutter an
cities were,

so scientists poured a liquid
cement into an old nest.

Once the concrete was set,

they dug away the earth to reveal
an extraordinary secret city.

There are subterranean highways
connecting the main chambers,

with side roads to fungus farms,
huge rubbish pits

and temperature-controlled nurseries.

This is one house
for 12 million inhabitants.

That's more than London or New York

On our scale, it is a mile deep,
and five miles across.

The social insects
are nature's finest architects.

These three-metre-high termite mounds
all point north to south.

In the morning and evening they
face the sun and are warmed,

but at noon, they are sideways on
and so don't overheat.

Our large buildings could follow
this simple trick.

However, this is not the whole story.

Half the year this is a swamp
and the sail-like shape and larger

surface areas are perfect for keeping
the colony dry, as well as warm.

Most termites avoid overheating
by descending into lower levels

during the hotter part of the day.

But these termites have found
an architectural solution

to the problem.

Finding an egg 1,000 times your
size in your house must be puzzling.

Terrifying, when it starts to hatch

The gigantic aliens
are lace monitor lizards.

Their exit is closed. The termites
repaired the hole in the wall

the monitor mother made
to lay her eggs.

They are trapped.

It seems almost incredible that the
mother would return to release them.

These lizards could not
have chosen a better nursery -

protected from predators

and incubated
at the perfect temperature.

The termites must repair the mound.

They use mud and mortar
out of their back end.

The walls are essential to stay
within half a degree centigrade

of 30, whatever the weather outside.

Far from the tropics, insects
have resorted to central heating.

In a hollow tree,
a Japanese giant hornet

starts to build a city with
cavity walls and electric radiators.

The queen first makes
a few compartments.

An egg in each hatches into a larva

It spins a silk cocoon for itself
that has extraordinary properties.

The silk is like a thermostatic
electric blanket.

It stores heat as electrical charge

which automatically turns back
into heat if the nest cools.

Her daughters pupate and emerge.

They are the first battalion
of builders.

They add additional floors,
suspended in the middle.

Supporting columns are moulded.

They build with chewed-up wood pulp
the same material as paper.

As more of the queen's larvae hatch
they start demanding food,

banging and scraping
their heads on the walls.

The workers collect insects and mas
them into a paste for the larvae.

The outside walls are extended
downwards, with up to eight

layers of cavity insulation,
and built-in flues and ducts.

Like the termites, a few simple
instructions may come together

to build a surprisingly
complex design.

Scientists call this
an "emergent property".

And what emerges, after four months

is a hornet's nest
almost a metre tall.

If it's cold, the nest is heated by
the larvae and their silk blankets,

but on hot days,
cooling air is fanned in.

This nest is held
within two degrees of 30.

The colony behaves as much like
a warm-blooded animal as a house.

Towards autumn, the queen turns to
producing new queens for next year.

She, and all her workers,
will soon die here,

exhausted and now expendable.

The city will crumble, too,
and can never be reused.

In the final days of her life,

the queen ensured that
a few larvae were fed

and fresh queen hornets emerge.

Each faces a winter of hibernation
and, in spring, starts building

a brand new edifice
40,000 times her size.

For every home,
there comes a time to move on.

There is one animal in the rainforests

that builds the most
extraordinary city of all.

Army ants kill almost
everything they can

and carry it all back to their home.

Their house is a living building
entirely made of ants,

called a bivouac.

The legs carry the weight
of the whole nest.

Big cities have big problems.

The ants generate so much waste
that they need a rubbish tip.

The carcasses of dead insects,
and old cocoons are taken

out of the city to the dump.

Soon the colony sits in a sea
of municipal waste

and all the surrounding food
has gone.

So, they unhook themselves at night
and set off.

Pupae and larvae are carried,
and the queen is protected

behind a cavalcade of soldiers.

A new site is chosen
and living ropes become columns.

They seem to build around a frame,

but since every site is different,
the design is never identical.

The frame is filled in with walls,

to create corridors and rooms,
all made of ants.

Their new neighbourhood will be
stripped of prey in a few days.

If the ants couldn't move their city,

they'd quickly eat themselves
into extinction.

All houses face the same dilemma.

The beavers have felled
hundreds of tons of wood.

After four or five years,
there is nothing left but bushes.

The ponds have silted up,
and without logs for repair,

things start to fall apart.

The beavers make do for a while
on shrubs, like willow herbs,

but even these, they eat faster
than can grow back.

As their lake shrinks,
they will abandon their home.

Almost all homes
become unsustainable, eventually.

The rivers are littered with
empty lodges and broken dams.

Every construction
is an attempt to tame nature...

and nature will always win,
in the end.

Things are even tougher
for prairie dogs.

In summer, the land dries.

The cattle and buffalo can move,

but the dog towns can't and the
families have nowhere else to go.

The owl family can all fly now.
They can come and go.

The prairie dogs
eat the remaining grass,

until their neighbourhood
becomes a dust bowl.

They face starvation.

The young are a few months old

and now the colony
turns against them.

Neighbours start to hunt down cubs.

Even cousins and aunts turn nasty.

In a dry year, up to half
of the young are killed.

Stuck underground, out of sight,
their home becomes a prison, a tomb.

THUNDER RUMBLES

Salvation does come in the end

for the few survivors
inside their houses.

In autumn,
the rains replenish the land

and, in spring, the grass grows back.

The prairie dogs
have done no permanent damage.

They help the grassland
over the years,

by mowing and fertilising
their gardens.

The neighbourhood returns to normal

The beavers have started a new life
a couple of miles downstream.

They have found ponds
built generations ago,

overgrown and abandoned.

They have repaired the dams
and re-opened the canals.

The trees here have regenerated,

thanks to the fertile silt
clogging the old ponds.

We can begin to see why
not every animal makes a home.

You can't rely on one place for long.

For many, the risks are too great.

The restless and the hungry follow
the seasons in great migrations.

The world is constantly changing

and even the wisest animals
struggle to keep up.

These are the homeless of the Earth

and, until recently,
we were among them.

So how did we become
the greatest homemaker of all?

Our closest animal relatives
are still homeless,

unable even to keep out of the rain.

Apes and monkeys
don't make shelters,

though a gorilla's hands and brain
are easily up to the job.

The priority for these mountain
gorillas is to find fresh food,

so they keep moving.
A house would only tie them down.

The signs of an ability,
however, are here.

An improvised roof is better
than none, while it lasts.

Our ape cousins build beds, or even
platforms, woven from branches.

But they never sit under them,
like a roof.

We may have started with twisting
branches into shelters,

but there is another way
to get out of the rain.

In Kenya, on Mount Suswa,
baboons use caves at night.

Caves like these contain the earliest
evidence of human habitation.

The monkeys' fingers
and sense of balance

take them along ledges impossible
for leopards and hyenas to follow.

Many of our phobias
may have originated here,

with bats and snakes,

and strange, ghostly noises
in the dark.

We probably became serious builders

only a few hundred thousand
years ago, at the most.

It is extraordinary
what we have achieved.

We don't often realise how fragile
all this is.

Our cities have all the
problems of animal cities -

burglars and squatters, and getting
the food in and the rubbish out.

To feed the city,
we eat up the wilderness.

We forget that we kick animals
out of their homes to do so.

Maybe we can be reminded
by the refugees,

by an urban generation
of peregrines and pigeons,

gulls and bats and foxes.

Animals will share our world,
if we let them.

We can make space and help
with protection, food and warmth.

We are homemakers, we understand.

We can build a world, surely,
where animals can have a home, too.

# I'm coming home, I'm coming home

# Tell the world I'm coming home

# Let the rain wash away

# All the pain of yesterday

# I know my kingdom awaits

# And they've forgiven my mistakes

# I'm coming home, I'm coming home

# Tell the world I'm coming. #