Narrator: The Ngorongoro crater
is an environment both beautiful
and unusual.
It contains an array of habitats
and a yearlong supply of water.
This ensures that it is always
teeming with life -
even at the
height of the dry season.
But this blessing
can quickly become a curse.
Its closed-off nature
has caused behavior unseen
anywhere outside of its walls.
This is Ngorongoro crater,
the cursed haven.
40 million years ago,
"The Rifting" began.
When the Earth's crust
along Africa's eastern plain
started to thin,
a massive fault line formed.
As the continent split apart,
the land
on either side collapsed.
And lava thrust up
from within the earth,
Leaving a massive depression
of highlands and volcanoes -
The Great Rift Valley.
2.5 million years ago
one of these volcanoes erupted.
The Ngorongoro volcano was about
the same size as Kilimanjaro.
Trapped lava from within the
base had nowhere to move,
and the entire mountain
imploded,
forming what is known
as a caldera.
For years it remained desolate
and uninhabited.
But as the fires settled
and the slopes cooled
vegetation started
to colonize the steep banks,
thriving off the rich soils
and moisture.
Herbivores followed
the flora over the rim,
and down into the crater.
Soon after,
the carnivores followed.
With no incentive to leave,
the animals have stayed here
ever since.
The result
is an oasis of wildlife
known as the Ngorongoro crater.
Covering an area
of 125 square miles,
the Ngorongoro crater
in Tanzania
is the largest
intact caldera on earth.
Today 25,000 large animals
make their home here.
Among these
is the greatest concentration
of carnivores on the planet;
Some of the world's
oldest elephants,
Largest grazers -
And most charismatic birds.
And their desire to stay
is closely related to the
unusual layout of the land.
The Ngorongoro crater
has a range of habitats
within one consolidated arena.
From plains
to freshwater swamps,
soda lakes,
forests
and wetlands.
During Tanzania's dry season
the crater's savanna
becomes frail and desolate.
Each resident must embark
on a migration
within the crater walls
to reach its water source.
The wetlands
in the center of Ngorongoro
provide generously
all year round.
Tempted to stay inside
because of its
permanent supply of water,
the inhabitants rarely step
outside of the sheer walls.
This has caused behavior
not seen
in any other animals
on the planet.
Imprisoned
by their natural instincts
they stay within this
amphitheater
even when it is
to their detriment.
Leaving the question
as to whether it is a paradise
or a prison.
Lions are the famed hunters
of the African savanna.
They are highly effective
pack predators,
able to take on large prey
due to their size and strength.
But the Lions in the crater
are different.
The dominant prides,
unwilling to share
in the bounty of Ngorongoro,
have chased away all migrating
Lions that attempted to enter.
Because of this,
the Crater has caused
what is referred to as
a genetic bottleneck,
limiting the gene pool.
All of the crater Lions
are descended from a single
isolated population.
Generations of interbreeding
have left these lions
more prone to disease.
Because of the consolidated
nature of the crater,
their natural survival instincts
have become
their biggest detriment.
Years of holding onto the spoils
of Ngorongoro
has taken its toll.
And this has caused
another inversion
in the usual hierarchies
of the animal world.
This is the only place
on the planet
where Lions are not
the kings of the savanna.
In Ngorongoro Lions scavenge
up to 80 percent of their food
from the dominant hyena clans.
The crater is home to 400
Spotted hyenas.
And here they are unmatched
for their size,
power, and hunting efficiency.
The crater hyenas
do not suffer from interbreeding
as the Lions do.
Males are chased from their
birth group
by the dominant females;
this forces them
to reproduce elsewhere.
The hyenas roam
the dry plains of the crater
as the unexpected
rulers of an unorthodox domain.
Even in the depths
of the dry season,
the Ngorongoro crater boasts
an abundance of residents.
And their desire to stay
is closely related
to the history of the land.
During the formation
of the Great Rift Valley,
a surge of landscapes emerged.
As the ground broke apart,
a range of new environments
and species were born.
The crater is a product
of this tectonic flux
and it has inherited some
interesting characteristics
because of this.
As clouds scrape the top of the
montane forest on the rim,
moisture is continuously flushed
through the system.
As a result,
it creates its own climate
separate from
the surrounding areas.
Even in the dry season when
everything else begins to wither
the crater forests
still flourish.
This dense greenery
is a result
of the unique
topography of the rim.
It is a forest haven, unhindered
by the changing seasons.
Every year
outside of the caldera walls,
tens of thousands of animals
migrate across the Serengeti
to escape Tanzania's dry season.
But the crater animals
stay where they are.
They circulate
around the crater floor
every day on internal migrations
in search of grazing and water.
Though the cloud forests
on the rim
maintain moisture
all year round,
during periods of drought
little of this trickles down to
the savanna on the crater floor.
And the majority
of the animals that live here
are confined to endure
this scarce habitat.
Wildebeest are restricted to eat
on the Ngorongoro crater's
savanna biome.
Their broad muzzle
and loose lips
are adaptations
suited to rapid, bulk feeding.
They feast on grass that
responds well to grazing,
trampling and manure.
They cannot graze
the grasses on the rim,
which are too delicate to deal
with the wildebeest's
boisterous eating habits.
This keeps the wildebeest
on the dry plateau below.
When rains are minimal,
these shallow-rooted grasses
quickly stop growing.
The confined nature
of the crater
means that the plains become
crowded wastelands
with little moisture.
But wildebeest
need to drink daily.
So they are limited to pastures
no further than 9 miles
away from water.
Every day they must embark
on a migration to the wetlands.
But they are not the only ones
caught in this unforgiving loop.
Ngorongoro is also home
to 4,000 Grant's zebra.
The two groups of animals
constantly feed
as they move across the crater
floor every day to the wetlands
in the search for water.
Where the wildebeest
prefer the shoots of new grass
closer to the ground,
zebra enjoy the coarser,
taller stalks.
Zebra are known
to be pioneer grazers,
moving over
a patch of earth first
and cropping it down to a
size that other species
including wildebeest, prefer.
Moving in bigger mixed herds
reduces an individual's chance
of being attacked
by creating an added distraction
from predators.
This makes traveling
in large numbers beneficial,
especially in the crater.
For the scavengers the dry
season is a time of opportunity.
Every life taken within the
crater is a chance to feed.
Golden jackals
stalk the grasslands,
eating whatever they can,
when they can.
More adapted
to an arid lifestyle
than any other
species of jackal,
they owe their success to their
ability to live on anything
from fruit and berries
to rodents and carrion.
They will eat
whatever food can be acquired
with the least amount of effort.
This is paramount in Ngorongoro
where they have much competition
from some formidable foes.
In Ngorongoro,
hyenas have dominion over all.
Hyena clans exist
in strict hierarchies.
Social rank is fundamental
to the success
of their highly
coordinated hunting excursions.
And strength is the principle
that underlies the whole system.
Females are ranked according to
how many fights they have won.
In their world the most feared
is at the top.
Their ferocity makes them
formidable hunters.
The best fighters
have priority at carcasses.
And they are highly territorial.
They roam this unusual land
as distinctive emperors,
unrivaled for both their
strength and hunting efficiency.
For the scavengers the dry
season is a time of plenty.
Tawny eagles are well-known
pirates of the savanna,
often intimidating others
off a kill
in order to enjoy it
for themselves.
Their keen eyesight
and rapid flight speed
ensure that they are
quick on the uptake
when the crater
claims an animal.
The flat, open nature
of the crater floor
provides ideal conditions
for another scavenger's
impeccable sense of sight.
Vultures soar on thermals
to look for carrion.
But the layout of the caldera
suits other birds too,
and not all of them favor
taking to the skies
in the search of food.
Secretary birds thrive in the
crater's barren grasslands
and this is because of the
structure of their body.
Secretary birds
prefer moving around
on their long powerful legs
over flying.
They can move over 18 miles
a day in the search for food.
Unlike most birds of prey,
their favored method of killing
is not with their beaks
but their legs.
Using these powerful pistons
to stamp smaller prey,
they are efficient predators.
And the desolate plains
of Ngorongoro
are the ideal hunting ground.
The open layout of the floor
is also important
for the crater's biggest bird.
Unable to fly,
Ostriches rely on their speed
to evade predators
like Lions and hyenas.
When they need to, they can
sprint over 40 miles an hour.
But when there is no danger
around they do something else.
This dance
is an invitation to mate.
Ostrich mating
precedes the rains.
This is so that their chicks
will be born
in the abundance of
the wet season.
And they are not the only crater
birds joining in the ritual.
Crowned cranes
eagerly await the rains.
These elegant birds
need permanent marshes
to make their nests.
But once again,
the dry grass is the reason
they have been drawn out
from their wetland homes.
The crater floor is a prime
hunting ground for them.
They are mixed feeders;
eating anything from insects and
lizards to flowers and seeds.
These short dry grasslands
enable them
to use their long limbs
to comb through the savanna
in search of smaller prey.
Like everything else
in the crater,
they need to make the migration
every day
from the dry savanna
feeding grounds
to the lush marshlands
in search of water.
Raising young in these
conditions is no easy feat.
Buffalo are the largest members
of their family
and they require a lot of water
to maintain their massive bulk.
But they too can only feed
on the dry grasses
of the crater floor.
Calves weigh just under 100
pounds at birth
and are largely
defenseless until they mature.
They are utterly dependent
on their mother's knowledge
to survive
the long periods of drought.
And they too must journey
between the crater's savanna
and its marshes every day.
Water is the driving force
behind the continued occupancy
of the Ngorongoro animals.
There are other areas nearby
that support life
throughout the year,
but their waters
are inaccessible to most.
The lakes of the Rift Valley
are a product of aggressive
geological forces,
and some have retained
inhospitable characteristics
because of this.
Before the Rifting,
there were no lakes in Africa.
But as the earth was violently
reshaped, water began to settle.
When the lakes
of the Great Rift Valley formed,
much of the ground was covered
in lava and ash.
As water
filtered through the ground,
volcanic chemicals
were carried into the lakes,
creating a hostile
aquatic world.
Lake Natron lies at the foot
of Mount Ol Donyo Legai,
60 miles
to the north of Ngorongoro.
Its caustic waters are strong
enough to corrode human limbs.
Only about 15 inches of rain
reaches it per year,
much of which is 'phantom rain'.
The water evaporates
before it has even touched
the surface of the lake.
As a result, the lake's waters
do not come from the sky,
but rather
from under the ground.
Little that comes into contact
with the volcanic waters
survives.
But a single-celled organism,
visible only when magnified
a thousand times,
thrives here.
Spirulina platenisis flourish in
the carbonate-rich water,
under high temperatures
and plenty of sunlight.
Providing a source of food
for one of the planet's
oldest birds.
The flamingo's
specially adapted bill
allows it to graze the upper
inch of the corrosive water
and harvest the Spirulina .
The heavy arch of the bill
allows great quantities
to be sucked over fine hairs
inside their mandible,
filtering out the food.
These waters can sometimes
exceed 120 degrees Fahrenheit.
A flamingo's hard, featherless
leg is one of the few things
that can withstand
the corrosive lake.
This allows them to wade to the
mud flats right in the middle -
And these are no more welcoming
than the surrounding waters.
Temperatures are high,
winds are strong.
Almost no vegetation survives,
and movement
across the thick muddy terrain
is impossible for most mammals.
The mud flats also create the
harshest nursery on the planet.
Using Lake Natron's volcanic
water as a moat
against all
land based predators;
the flamingos have made
the barren ground in the middle
the ideal breeding site.
This is the largest flamingo
breeding ground in the world.
The land's unusual
and inhospitable nature
has given them exclusive feeding
and breeding rights.
But they are not the only
creatures that have adapted
to withstand
the volcanic waters.
The Alkaline tilapia.
These fish live on the edge
of the hot spring inlets
where the water reaches
100 degrees Fahrenheit.
They have evolved
to endure the high temperatures
and dense alkalinity.
The only places in the world
that they occur
are the soda lakes
of the Great Rift Valley.
The landscape is harsh
and unyielding
yet over time
life has adapted to survive.
Thriving off the volcanic
hostility and unusual geography,
the animals that live here
have learned to cope
with the severe landscape
and in return
they are provided with a haven.
Because so few animals
can survive here,
the inhabitants
of the Rift Valley soda lakes
have their own sanctuary
crafted from lava and ash.
The anomalous formation
of the crater highlands
ensures that Ngorongoro
has water all year around.
Outside of the caldera
the nearby Empakai crater
remains full and luscious,
regardless of the surrounding
changes in climate.
Water moves from this basin
into Ngorongoro,
feeding its wetlands
throughout the year.
And this enables animals
to live here
no matter how little
is provided by the rain.
Every day the inhabitants must
make the walk
across the crater's savanna
to reach
its enduring water supply.
This brings
the entire population
of the crater together.
Though they all have different
feeding requirements,
every animal needs to drink.
Throughout the day
they spread to different sides
of the crater floor,
but when it is time to get to
the water the entire range
of the park's wildlife
all funnel towards the marshes.
The Ngorongoro crater
is a sanctuary for Tanzania's
last few remaining Black rhinos.
Even when the dry season
is at its harshest
they are provided with water.
They are normally elusive,
hiding within the forests.
But they are drawn out to join
the rest of the residents
in the search for
nourishment.
The wetland is the life force of
the Ngorongoro crater.
It ties together
all of the park's residents.
It is the only reason
that they can endure
the severity of the dry season.
The Ngorongoro waters
support all stages of life
from the youngest animals
to some of the planets oldest.
It is a haven
for old elephant bulls
that wander inside the crater
for the safety
and seclusion that it offers.
Elephants' tusks keep growing
their entire lives.
By the time a bull
is 60 years old
his tusks can reach a
combined weight of 260 pounds.
As a result,
the Ngorongoro elephants are
endowed with tusks of a size
seldom seen
outside the crater walls.
For the waterfowl,
the wetland is a constant home.
Great white pelicans are bound
to the water throughout the day.
In the morning
they will hunt for fish
and for the rest of the day
they will
socially bathe and preen.
Their fishing techniques
see them dependent
on the shallow warm waters.
They are joined
by other birds on the hunt.
The Yellow-billed stork's
odd shaped bill
is perfectly adapted
to fishing in drying rivers.
As fish become trapped
in shallower pools,
the storks use their feet
to stir up the muddy water
before stabbing fish
with their sharp beak.
They also have an intriguing way
of cooling themselves
in the heat of the day -
While standing around preening
they will urinate on themselves
to cool their legs.
As the urine crystallizes,
the whitish colors act
as a screen to reflect the sun.
For them water is a constant
source of food and nourishment.
And the crater's wetlands
are a constant home
for another far larger resident.
For hippo to live comfortably
they need a water source
that is deep enough for them to
submerge completely -
And they also need
to be close to grasslands.
These pools provide them
with the ideal home.
This water haven is
the beating heart of the park.
It supports and provides for all
of its residents all year round,
and without
its dependable sustenance,
life in the crater
would not be able to endure.
The sheer 1,900 foot drop
of the caldera walls
sever this landscape from the
surrounding areas in many ways.
It has its own apex predators,
a separate climate
and a wealth
of habitats unseen outside.
But what is on the face of it
a wildlife oasis
may just be something closer
to a natural prison.
Even at the height of drought,
most animals stay and endure
the severity of the land.
It is a constant home
for herbivores
no matter how frail
and overpopulated
the grasslands become,
or how many predators roam
the enclosed amphitheater.
Seduced by the temptations
of a yearlong water supply,
abundant grazing and large
numbers of prey;
the inhabitants were tempted
over the crater walls
thousands of years ago
and many of their descendants
have never left.
Shackled
by the promises that it offers,
their instincts for survival
keep them bound to Ngorongoro,
even when this is
to their detriment.
The life that endures here does
so according to its own rules.
Produced by the hostility
of a volcanic environment,
the Ngorongoro crater
is both a generous habitat
and a dangerous trap.
And each of its residents
has to navigate this boundary
in the daily search for water.
The result is an animal kingdom
like no other.
