[Tom Hiddleston] The night.
A shadowy world that hides more than half the animals on our planet.
Until now, cameras only offered a glimpse into their lives.
But with next-generation technology,
we can see the night as clear as day.
With cameras a hundred times more sensitive than the human eye...
we can now capture the beauty of night...
in color.
Alien landscapes.
Strange creatures brought to life by the darkness.
Unseen behaviors.
Now we can follow the lives of animals
in Earth's last true wilderness.
The night.
Sunset over the plains of Kenya's Maasai Mara.
One of Africa's most protected wild spaces.
And home to the fastest land animal on Earth...
the cheetah.
These agile cats have always been thought of as daylight hunters.
They target prey from more than a kilometer away.
And chase it down at over 100 kilometers an hour.
Fewer than half of all hunts end in a kill.
And this evening, this young male has blown it.
[purrs]
Fortunately, he's not alone.
[purrs]
Cheetahs are usually solitary.
But he has a brother.
Since the day they were born, these 4-year-olds have been inseparable.
Working together, they defend a prime 60-square-kilometer hunting ground.
[braying]
But tonight, a failed hunt means the brothers have wasted precious energy
and must feed soon.
[brays]
[wind whistling]
As dusk draws in...
it seems their chances of making a kill are fading.
But following these brothers through the night...
tells a different story.
With low-light cameras...
we can now see the cheetah's nighttime world...
in a whole new way.
Under moonlight...
cheetahs lead a secret nocturnal life.
[purring]
The brothers are playful and surprisingly vocal after dark.
[screeches]
[purrs]
Cheetahs can't roar like most big cats.
But they can purr.
[purring]
In house cats, it's a sign of contentment.
But it's thought cheetahs also purr to strengthen their bonds.
-[growls] -[purrs]
And tonight, the brothers will need each other more than ever.
[purrs]
They must hunt.
Most cats are nocturnal.
But cheetahs have eyes adapted for daylight.
So the brothers struggle to see in the darkness.
But our cameras now allow us to see more than them.
[grunting]
Prey animals usually keep as far from predators as possible.
But at night, wildebeest reveal a surprising way to stay safe.
[grunting]
Wherever the brothers go...
[hoofbeats]
...the herd follows.
[grunting]
The trick is to keep the cheetahs in sight at all times...
[grunting]
...while staying just far enough away...
[snorts]
...to make their escape.
[grunting]
But the brothers have played this game before.
-[grunts] -[snorts]
It seems impossible that a cheetah with poor night vision...
would attempt a high-speed chase in the dark.
But it's recently been discovered...
that one-third of cheetah kills take place at night.
[bird squawking]
A skillful hunter, he swiftly overpowers his prey.
But what happens next shows how tough life can be for the brothers after dark.
The herd closes rank.
Together, they can drive a cheetah off a kill.
His brother is there to protect him.
But that's just the start of their problems.
[squeals]
Within seconds, the kill attracts a hyena, a nocturnal scavenger.
[hisses]
[growls]
Far stronger than a cheetah...
one hyena can match both brothers.
They must now fight to keep their kill.
But this thief is not alone.
[laughing sound]
[hisses]
[growls]
[hisses]
In the Maasai Mara, hyenas live in gangs 60 strong.
And 1 in 10 cheetah kills are stolen.
[squeals]
Hunting at night...
is a whole new world.
[squeals]
-[growls] -[laughing sound]
They will have to try again.
But cheetahs aren't the only animals out here searching for food after dark.
On the banks of Africa's rivers...
over 100,000 hippos leave the safety of their watery homes...
to set out on an extraordinary nocturnal mission.
[snorts]
By day, hippos are notoriously lazy river dwellers.
Preferring to wallow in the water and hide from the hot sun.
But at night, they are remarkably active.
Well-trodden trails lead them ten kilometers out across the open savanna.
They come here in the cool of night to graze.
Chomping through up to 50 kilos of grass and plants per night.
By eating on such a scale,
these secret night gardeners are playing a vital role...
shaping the grasslands
and fertilizing this rich and diverse ecosystem.
[snorting]
[growls]
So far from the safety of the river...
it can be a little risky.
[snorts]
But when you're a three-ton lawn mower...
even Africa's most imposing predator...
has to get out of your way.
With their surprising free rein over the grasslands at night,
we are beginning to see hippos in a whole new light.
Under clear skies and a full moon...
the cheetah brothers continue to hunt, having lost their hard-won kill.
But they're not the only cheetahs out here tonight.
On the fringes of their territory...
[purrs]
...their sister is getting some rest.
And she needs it.
She has four one-year-old cubs.
They're already fed.
All she wants to do now is keep them safe.
[purring]
[growling in distance]
But she can sense trouble in the darkness.
[growling]
Hyenas.
They can kill young cheetahs.
Her one-year-olds might look fully grown.
But they are lighter and weaker than adults.
It's safer to move them on.
[laughing sound]
A whole gang has got wind of the young family.
[laughing sound]
Hyenas are territorial and will bully weaker rivals off their patch.
[laughing sound]
The hyenas close in...
surrounding the family.
[hisses]
-[hisses] -[laughing sound]
-[squeals] -[hisses]
Young cheetahs have the lowest survival rate of any of the large African cats.
[laughing sound]
Their only defense is to make themselves look bigger than they are.
[hisses]
The mother's last resort is a bluff charge.
-[growls] -[squeals]
She's running out of options.
[hisses]
But the most unexpected things can happen at night.
[trumpeting]
A young bull elephant in must.
[growls]
He's a four-ton giant, raging with 50 times more testosterone than usual.
And he's had enough of all the commotion.
[growls]
The fastest land mammal saved by the biggest.
[growls]
We're only beginning to understand
the strange things that take place on the African plains at night.
Back in the brothers' territory...
their persistence has paid off.
They've made another kill.
[thunder rumbling]
Once again, a familiar character is quick on the scene.
[hisses]
But this time, something unusual happens.
The hyena doesn't call in the rest of its gang.
And rather than fight for their kill...
-[growls] -[hisses]
...the brothers decide to share.
[growls]
[hisses]
The two rivals accept an uneasy truce.
Finally, the brothers get their fill.
Cheetahs have long been considered daytime cats.
But only now are we discovering...
they live complex nocturnal lives.
[thunder rumbling]
Following these two brothers night after night...
shows a powerful but surprisingly fragile side...
to the world's fastest land animal.
Filming cheetahs hunting in the dark...
was one of the Earth at Night team's hardest challenges.
I've filmed cheetah hunts during the daytime before
but this is the first time I've ever tried to get one at nighttime.
[chattering]
[Tom Hiddleston] Cheetahs are more likely to make a kill around full moon.
But the brothers seemed to have other things on their minds.
[Pilcher] Yeah, they're coming.
[Tom Hiddleston] They spent most nights scent marking their territory...
just like house cats.
[Pilcher] A cheetah's biggest habit is going from one tree to the next tree...
to the next tree.
And I've got a lot of them doing that.
[laughs]
[whirring]
[Tom Hiddleston] Following the brothers in the darkness...
the team saw just how much space these cats need to survive.
But all too often, they were confronted by a glaring issue.
So what we're seeing with our cameras we're picking up towns,
maybe 10 kilometers away.
It just reminds you
how close these extraordinary predators are to living with people.
[man] These areas are really good
for the conservation and protection of these predators.
But at the same time,
with the increasing human population growth and, uh, demand for land,
you know, they are still vulnerable.
[Tom Hiddleston] There are around 7,000 cheetahs left in the wild.
And their range is decreasing year-on-year.
Even in one of the most protected wild places on Earth,
our night cameras show humans are never far away.
Following the brothers in the darkness...
the team finally got their chance.
Just another meter or so. Okay, just go slowly.
Okay, no problem.
[engine stops]
[Pilcher] Okay, looks like one of them is starting to run in. Hold still, everyone.
It was actually quite amazing to finally get it.
I was starting to think we-- we wouldn't.
You gotta be so quick and hope
that you're kind of in the right place at the right time.
The hyena are coming in already.
Incredibly fast.
An amazing hunter, but yet so fragile.
[Tom Hiddleston] After months following the cheetahs...
the team captured behaviors new to science.
And in doing so...
revealed a secret nocturnal side...
to these iconic African cats.