(insects chirring)
(wind whooshing)
As calm as the natural world appears to be,
it's home to some of the craziest
and most interesting sounds, from the choruses of cicadas
and frogs during courtship to the loudest call on land,
underwater songs, flying calls,
and the noisiest, most evolved adaptations on Earth.
Discover with us how and why
different species use the power of sound.
(dramatic music)
Animal alerts.
The North American prairie.
Large animals like the bison can see predators approaching
in the tall glasses of the great plains.
But for the little ones like this prairie dog,
tall grass is not the best option.
Mowing the lawn is an everyday task
that helps these mid-sized rodents
maintain a watchful eye on the colony.
But a short lawn alone is not enough for safety.
And these little fellas have another strategy.
(prairies dogs chirping)
Often called the architect of the prairies,
prairie dogs form colonies of millions of individuals
who excavate the plains with their burrows.
These burrows become home to most species in the prairies.
Communication is key to efficient colonial living.
This is why prairie dogs have developed
a wide repertoire of vocalizations,
from territorial calls that let know
other individuals they are at the wrong place
to barely audible chirps between mothers and babies.
(uneasy music)
One call snaps everyone to attention.
It warns: predator in the neighborhood.
(yipping)
The entire colony runs to the burrows for protection.
The sharp, repetitive bark echoes across the area
to assure that all the clan members will not miss the alert.
The coast is clear.
And they jump and yip to celebrate, a very important call
to bring back peace and joy into the colony.
(yipping)
Not everything is a jungle out there.
Howler monkeys take things slow.
And spend great part of their day eating.
(calm music)
And after eating, they need to rest.
This is basically what howlers do.
This quickly becomes too boring for the babies,
and they soon leave to play.
The youngest are still fearful to leave the adult's side.
It looks too much fun to miss it.
It seems that just the kids have fun in the jungle.
Some moms watch vigilantly, while most adults rest.
It's hard to imagine that these adult monkeys
could actually be loud.
(growling)
One would never know that these loud growls
aren't from an angry jaguar but the sleepy howler monkeys.
(growling)
Male howlers have evolved
a greatly enlarged, cup-shaped hyoid bone.
The enlarged hyoid bone contains an air sac
that functions like a resonance chamber,
increasing the volume of their calls.
(growling)
The howling is thought to relate to territory protection
as well as to guard mates possibly.
The roar of the lion can be as loud as 114 decibels,
similar to a rock concert, while the trumpet of an elephant
can be as noisy as a clap of thunder, about 130.
A male howler's call can reach up to 140 decibels,
as strident as a jet taking off.
(jet whooshing)
Their distinctive call can be heard up to three miles away,
making howler monkeys the loudest
land animals on the planet.
Mammals aren't the only ones
that use sound to protect themselves.
There are creatures that make themselves
almost invisible to predators and to prey.
(curious music)
Yet camouflage can be risky as well.
You might get stepped on.
This unique warning sound might just avoid a fatal ending
for both the snake and the human.
(rattling)
Rattlesnakes are a group of venomous snakes
of the genera Crotalus and Sistrurus.
The scientific name Crotalus
is derived from the Greek meaning castanet,
while Sistrurus means "tail rattler".
It shares its root with the ancient Egyptian
musical instrument the sistrum, a type of rattle,
making its scientific name all about sound.
Because of its rattle feature, evolutionary biologists
classify rattlesnakes as the newest and most evolved snakes.
A snake of this kind can waggle its tail in such a way
that it produces a rattle 50 times in a single second.
Even more impressive, it can sustain that rattle
for more than three hours.
(intriguing music)
The rattle is made of keratin,
the same material in fingernails.
It is formed by hollow, interlocked segments
that fit loosely inside one another.
At birth, rattlesnakes only have
a single segment of keratin, called the pre-button,
unable to produce any sound.
It's only after their first shed of skin,
with the new button fully formed,
that the rattle produces sound.
When the snake vibrates the muscles in its tail,
the segments collide with each other.
It sounds like a baby rattle at the early stages,
but the sound grows in volume as they shed skin
while getting larger and add new segments.
Then, they can produce the terrifying sound
that gives rattlesnakes their name.
Yet the rattle is what deters predators
or serves as a warning to passersby
and the reason why they rarely bite humans.
In fact, biting is their last defense.
Most rattlesnake bites are caused by humans
stepping on them, and 20% of all venomous snake bites
are dry, which means they don't inject venom.
In fact, only one out of 500
venomous snake bites result in death.
Nevertheless, if you wander into their habitat,
keep an eye on where you step,
and be aware of their rattling noise.
The high-pitched rattle, their striking pose,
and a terrifying hiss is their attempt
to keep danger away from them.
(rattling)
the next time you explore nature,
try to pay close attention to its sounds.
You might be listening to much more
than just a chirp or a howl.
It might be an alert, or a courtship call,
or just a song to have some fun.
It could even save you from a venomous encounter.
This is the power of sound.
(bright orchestral music)