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The great grasslands of Africa.

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A vast landscape.

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Buzzing with life.

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This is a world dominated
by the loudest voices.

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But if you listen carefully...

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there are secret sounds hidden
in the grass.

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Welcome to Earth's
weirdest acoustic contest.

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A serval. An elusive African wildcat.

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And the grasslands ultimate sonic spy.

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These hunters search for prey

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using their oversized ears
to tune in to every sound.

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In a landscape where it's impossible
to see far...

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relative to its size, the serval
has the largest ears of any cat.

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Allowing them to map their world
through sound.

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And there's one tiny noise
deep beneath the grass

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that they're tuned in to above all others.

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The footsteps of striped mice.

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Their satellite-dish ears
can move independently,

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thanks to ten muscles in each.

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Giving perfect surround sound.

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But to really dial in to their prey,
rather surprisingly,

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the serval sits down.

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While most cats stalk,
their hearing is so good...

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they can hunt with their eyes closed.

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They can detect the footsteps of a mouse
from more than ten feet away.

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And may remain motionless
for up to 15 minutes.

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Patiently waiting for their prey...

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to make the slightest noise.

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Once locked on,
the serval faces one more challenge.

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How to make a move without being heard.

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And to do this... they get airborne.

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Leaping up to six feet high,

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they can strike with pinpoint accuracy.

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Servals have one
of the highest hit rates of any cat.

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Twenty percent more successful than lions.

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And it's all thanks
to their amazing ability

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to hear the tiniest sounds on the savanna.

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From the quietest to the loudest.

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Across Africa's vast grasslands,
there's one sound...

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that transforms this landscape
like no other.

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Thunder is the starting gun
for Africa's Great Migration...

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detected from over 90 miles away.

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Thirsty, growing grasses pop
as they suck up water

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and tiny air bubbles from their roots.

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The lush vegetation brings together

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the greatest gathering
of large mammals anywhere on earth.

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It's a cacophony of life.

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Set in motion by the simple sound
of thunder.

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In such a packed arena,

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Africa's acoustic contest
hits a whole new level.

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And perhaps the most astonishing trick
is performed by tiny insects...

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who use sound to help protect their home
from giants.

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Cocktail ants.
Less than half an inch long.

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And named after the habit
of cocking their tail-like abdomens.

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They live in a certain species
of acacia tree

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that have evolved hard,
thorny growths which house the ants.

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The tree also provides food.

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Secreting a sugary sap for the benefit
of the hungry insects.

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For the ants,
life on their tree would be perfect

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were it not for one rather large problem.

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Ants are not the only animals
that adore acacia.

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Eating over 200 pounds of food a day...

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an elephant can destroy a tree
in minutes.

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So the insects have come up
with a remarkable way of using sound

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to keep their acacia safe.

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New science suggests the ants
have learned to burrow entrance holes,

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largely on the windward side
of their nests.

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As the wind picks up,
the tree begins to whistle.

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The ants have turned their tree
into a giant woodwind instrument.

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And these whistles are carried
on the breeze.

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It seems elephants have learned
this is a warning call.

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A whistling acacia is infested
with biting ants,

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and one best avoid it.

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But the ants' system isn't foolproof.

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When the wind drops, the warning fades.

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And the tree can quickly find itself
on the menu.

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From an ant's perspective...

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an elephant grazing is a disaster.

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But the insects have another
acoustic trick.

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When alarmed, they rattle their abdomens.

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Producing vibrations known
as stridulation.

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Now new technology allows us to eavesdrop

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on this strange insect chatter
for the first time.

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The vibrations travel along the branches,

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mobilizing the colony
in less than a second.

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This secret call to arms allows the ants
to coordinate their attack.

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Biting the elephant's eyes,
and sensitive trunk.

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Faced with 25,000 angry insects,

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even the largest
of all land mammals turns tail.

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It seems impossible,

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but by teaming up to create one
of nature's weirdest warning calls,

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cocktail ants can see off an animal
one billion times their size.

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Insects aren't the only animals
to strike unlikely partnerships

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with their neighbors.

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Cape buffalo.

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These animals have formed
a quirky alliance with a noisy wingman.

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Yellow-billed oxpeckers spend most
of their lives perched on their host,

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picking off parasites.

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No respecters of personal space,

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the birds will go anywhere for a tidbit.

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Intimate cleaning
isn't the only service they provide.

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Nicknamed "the watch bird,"

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they've evolved a highly effective
alarm system.

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The buffalo have learned
the oxpeckers' shrill calls mean trouble.

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Lions.

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Africa's top predators.

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For these big cats,

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sound can hold the secret
to a successful hunt.

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With the buffalo spooked...

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a warthog could be an easier target.

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To avoid alerting her prey,

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this 300-pound lioness
must tread carefully.

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For stalking requires absolute silence.

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Over 80% of lone lion hunts
end in failure.

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Today it seems she
and her family will go hungry.

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However, during the wet season
there's a dramatic change

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in the acoustics of the savanna.

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And it's this, along
with the background din of wind and rain,

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that turns the odds in the lion's favor.

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This chaotic new soundscape...

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drowns out the footsteps of the pride.

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It's a phenomenon ecologists call
acoustic masking.

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Allowing the lions
to fan out across the plains.

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Undetected by prey.

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The perfect conditions
for getting closer than ever.

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But of all the animals
in the grasslands' great acoustic contest,

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there's one star performer

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that's taken finding a mate
to flamboyant new heights.

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A Jackson's widowbird.

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This young male is new to the mating game.

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And to attract a female

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he needs to master one the grasslands'
most complicated chat-up lines.

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For the last two days, he's been busy.

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Constructing
a three-feet wide amphitheater,

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complete with a strange central tuft.

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Now, to draw in a female,
he begins his courtship call.

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But this little bird faces a big problem.

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From down in the grass,
his efforts go unheard.

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Deadened by dense vegetation.

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But the widowbird is a specialist
at hitting the high notes.

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Jumping up to three feet,
he clears the undergrowth.

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Broadcasting his distinctive trill
at the peak of each leap.

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He calls nonstop for up to 20 minutes,

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until he catches the ear of a female.

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But he's not the only bachelor
out to impress.

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There are other males.

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Lots of them.

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All trying to attract the female
by outjumping

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and out-calling him.

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To entice her over,
he must give it everything he's got.

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Now he takes his performance
to next level.

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Shaking his magnificent tail feathers
like a giant rattle,

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he creates a stream of rapid-fire clicks.

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But then things get even stranger.

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Circling around his giant tuft,

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he hides from his date.

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When the female moves, he counters...

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because he wants
to impress her purely through sound.

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It's known as a peekaboo display.

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Only when he believes she's been wooed,

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does he bring out the final chat-up line.

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A make-or-break gurgle.

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Has he done enough?

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Sadly, no.

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This time, his bid ends in frustration.

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In Africa's grasslands,

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even the most flamboyant performance
doesn't guarantee success.

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The widowbird will have
to sing again tomorrow.

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To capture the sounds
of the African plains

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in more detail than ever before,

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sound recordist, Sebastian Dunn,
traveled deep into Kenya's Maasai Mara.

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I'm in the most beautiful place.

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{\an8}It's an absolute treasure trove of sounds
that I didn't even know existed.

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One of the many recordings
Sebastian wants to capture

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is the intimate calls
of Africa's biggest predators.

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And to do that, he has to get creative.

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To get a microphone really close
to the action, I thought,

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"Let me design a sound buggy
to take the microphone to the animals."

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The sounds I'm hoping to pick up

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are hopefully
the little micro communications.

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They're really difficult
to get when you're quite far away.

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Right. Here we go.

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But early tests
don't go according to plan.

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Yeah, it's holding it.

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She's got it in her claws.

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That's not what I really want to happen.

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I'm gonna just move it backwards
a little bit,

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just to-- hopefully, she'll move away.

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It isn't long
before the lions accept the buggy.

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And Sebastian begins
to capture the sounds he's after.

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The subtle vocalizations
of cubs asking for milk.

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And the unique play calls they use
to build bonds

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that will be crucial for their survival.

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As well as more intimate sounds,

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Sebastian also wants to record the
most iconic sound of the African plains.

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The lion's roar.

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To do that, he teams up
with lion conservationist, Nic Elliot,

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who knows of a dominant male
that is particularly vocal.

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From this close,
a lion's roar is over 100 decibels.

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As loud as a motorcycle.

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Wow. That was amazing.

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00:28:55,903 --> 00:28:57,738
Did you feel that?

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I felt it in my chest.
That is so impressive.

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But it's only when Sebastian
compares different recordings of roars,

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that he notices something remarkable.

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Here's the sonic signature
of the male's roars.

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A beautiful signature.

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Okay.
So, that's one individual, so--

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That's one individual.
Another individual is that one.

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The actual sonic signature
looks completely different.

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- Yeah.
- It makes me think

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that each individual
has its own sonic footprint.

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So that's really interesting.

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These tiny differences
in lion vocalizations

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could transform the way conservationists
track lions in the wild.

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If you can identify different individuals,
then that--

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yeah, that starts to become
incredibly useful

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and exciting for monitoring.

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It's brand-new science.

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In the future, the lion's roar could play
an important role

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in tracking and conserving
this African icon.