The vegetation of the rainforest is thick
and seeing through the impenetrable green
is impractical; so for animals, communicating
through sound is often the only way to send
a message.
To an observer on the ground the canopy is
experienced as a green roof with the sounds
of canopy animals wafting down.
Despite being exposed to the open air, the
canopy is not ideal for sound propagation,
making it actually quite hard to send a message.
So the calls of animals up here have to be
loud, Like those of the emerald toucanet.
A simple call, it is quite loud and carries
over the canopy.
its larger relative the keel-billed toucan
is even louder.
Its harsh notes can easily be heard from over
800 meters away.
The roaring call of howler monkeys rolls over
the canopy, carrying for nearly 5 kilometers.
It is one of the loudest noises produced by
a terrestrial animal.
This howling, which is often heard in the
morning but occurs throughout the day, is
thought to be a territorial signal to other
monkey troupes, telling them that this patch
of forest is taken and to stay away.
They have an enlarged hyoid bone which serves
as an attachment for many muscles involved
in sound production such as the tongue and
larynx; in howler monkeys it is also pneumatized,
hollow like a bird bone, and so an air sack
can fill the space aiding in producing a louder
call.
These Aluatta palliata howler monkeys have
the smallest hyoids in their genus, and do
not howl as long and have a narrower bandwidth
of higher frequencies they can produce in
relation to other howler monkeys
Not all the sounds in the forest are produced
from the throat and mouth of the animal sending
the signal.
This double knock sound is the territorial
drumming of the pale-billed woodpecker.
This is one of the largest woodpeckers in
Central America.
Like the howler monkey’s howling roar, this
loud double rap tells other woodpeckers to
stay out of the area.
Other sounds in the forest though, send the
opposite message.
Male long-tailed manakins work in male pairs
to attract females, which is accomplished
with a loud duet of toledo calls that rings
through the forests.
they sing starting in february and end months
later in september.
Perched in the lower canopy, the duet can
be heard over 250 meters away.
These birds will make around 5,000 such calls
over a day during the peak breeding season
in April and May, and as many as 300 in an
hour.
In the premontane rainshadow forests of Neotropical
mountain ranges, such as the tilaran mountains
of Costa Rica, another bird sends out a sound
signal to attract mates...
This is the matting call of the three wattled
bellbird, one of the loudest sounds made by
any bird in the world.
This strange noise can be heard from about
800 meters away on the forested slopes.
While he calls his three extremely weird looking
wattles are extended and dangle down from
the base of his beak.
Before he calls you can visibly see the bellbird
inhaling air, with his mouth staying wide
open… then the loud bonk rings out.
After the bonk the bird makes a few other
notes, ending with a loud squeak.
For the three-wattled bellbird, howler monkeys,
toucans and other canopy animals the key to
sending a clear signal is volume, belting
out as loud as they can for both tertiary
and love in this sea of green, high above
the ground.
