[INSECTS CHIRPING]
[MUSIC PLAYING]
SPEAKER 1: The tropical forests of Colombia
are home to a myriad of plant and animal species.
Like many of the world's forests,
this one in the Middle Magdalena Valley is also under threat.
As Colombia's human population grows, huge swaths of forest
are cleared for farmland and cattle ranches.
The remaining patches of forest become fewer
and further apart from each other, in a process ecologists
call habitat fragmentation.
Fragmentation threatens the survival
of all animals that live in the forest,
by reducing the amount of habitat.
And converting what's left to patchy, disconnected areas.
That is particularly true for the largest
primate in the Americas-- the brown spider monkey.
They rely on trees for their food and shelter.
And a continuous forest canopy acts as a highway,
providing them the freedom to move.
ANDRES LINK: The situation with brown spider monkeys
in Colombia, is very, very critical.
They've lost more than 80% of their forests.
SPEAKER 1: It's clear that spider monkeys
rely on forests to survive, but do the forests also
rely on spider monkeys?
[MUSIC PLAYING]
Wind, water, or animals can carry seeds from a parent plant
to new locations.
The seeds of tropical tree species
are primarily dispersed by animals that eat fruits.
SPEAKER 2: Many animals eat hundreds and hundreds, if not
thousands, of fruits in a day.
Most of them will swallow the seeds
and will defecate them in other places.
And through this process, disperse them
in different parts of the forest.
SPEAKER 1: Spider monkeys eat large amounts of fruits
to support their size.
And are likely, a major seed disperser in Colombian forests.
When seeds simply fall in the forest,
they end up near their parent tree.
Here, seeds compete with other seeds from the same tree.
Their chances of survival are low,
but seeds that are carried away by spider monkeys
and other dispensers are more likely to survive and grow
into a healthy plant.
Fragmentation reduces forest regeneration in two ways.
It decreases the number of seed dispensers.
And it limits how far they can safely travel.
Andres Link and his colleagues have
come to the middle Magdalena Valley
to measure how many seeds spider monkeys are dispersing.
And from which tree species.
ANDRES LINK: So we started to wonder,
what is the role of these primates in the dispersal
of seeds of many plant species?
CAROLINA URBINA MALO: They help to regenerate the forest,
and it's very important to know which species are they eating
because in that way, we know which species are going
to spread and which are not.
SPEAKER 1: The first step is to collect
the seeds dispersed by an individual monkey in a day.
SPEAKER 2: And what we do, literally,
is to follow them the whole day long.
We see that they're going to defecate,
and we pay close attention.
But also, normally we hear that some seeds
fell that a monkey defecated.
Then you can hear it, how it sounds when it
hits the leaves and the ground.
But when we can't find it, what we do
is that we rely on those animals that are specialists in getting
to these fecal samples.
We just have to stay really still.
A couple of seconds, you'll start
hearing some buzzing that increases
and increases in sound.
CAROLINA URBINA MALO: The dung beetles
have a very particular sound.
So you will follow the sound, look for that dung beetle.
And they will be making a little bowl from the poop
that you want.
So you will just take it.
SPEAKER 2: So we have some dung beetles here collecting
the poop.
So there must be seeds around.
And we can find something here.
We collect each fecal sample in an individual plastic bag.
And we put an individual number to each bag
because we're interested in quantifying,
not only seed dispersal of the species,
but also the ability of each individual.
Or the amount of seeds that it can disperse in a single day.
Or to find difference between males and females or.
In matures and mature animals.
A single spider monkey can defecate, probably,
between 13 and 17 times a day.
And this is only one monkey.
And these will represent 100, if not thousands, of seeds
that a single monkey disperses in this forest.
SPEAKER 1: They clean the seeds they've
extracted so they can be further characterized and cataloged.
This work takes place back in their lab, in Bogota.
ANDRES LINK: In the Middle Magdalena,
these spider monkeys can disperse about 100 species
or maybe more.
As we learn about the important role of spider
monkey seen in dispersing the seeds of many plants.
And at the same time, we see how populations are declining.
We start to worry a lot about the future of these forests.
SPEAKER 1: With fewer spider monkeys,
the forest is less able to regenerate,
further decreasing the spider monkeys habitat.
Researchers are trying to break this cycle by replanting
the seeds they found.
They plant them in deforested areas
that are no longer used for agriculture.
They will grow into the trees that monkeys
need for food and shelter.
ANDRES LINK: So what we do is that we collect those seeds,
and we plant them in areas that have been degraded.
Especially, we planned them in areas
that we have identified that can be
potential corridors between isolated patches of forest.
SPEAKER 1: Growing these trees in the areas between forest
patches will allow spider monkeys to move from one patch
to another, increasing both their chances of survival
and their ability to disperse seeds.
ANDRES LINK: We really think this process of restoration
and connecting these forests will provide a future scenario
that is much nicer.
A future scenario in which monkeys
will not depend on us to have a viable population
going on there and surviving without the need
of our assistance.