The brown howler monkey is a species

endemic to the Atlantic Forest.

It was considered a species vulnerable to extinction,

and now it’s considered endangered.

The male is slightly larger than the female,

he is red-haired and he produces a very characteristic
and famous vocalization,

the howl, which can be heard from kilometers away.

They use this vocalization to mark their territory.

The reintroduction of howler monkeys began in 2015,

as the second species reintroduced in Tijuca,
after the red-rumped agouti,

and originally it was a group of five animals

that were placed here at that time.

Well, we’re in the Tijuca Forest,

which is a national park,
Tijuca National Park,

within Rio de Janeiro, within a metropolis

of 6 million people, one of the
largest urban forests in the world

and a forest that has quite an interesting history

because it was a forest that was partly replanted

around 170 years ago.

Refauna was born out of the perception of an empty forest,

the realization that Tijuca was here,
in the middle of Rio de Janeiro,

an empty forest that,
like many other forests in the tropics,

deserved an effort so that we could
try to rebuild the native fauna

and make this forest work again as a healthy ecosystem.

The howlers have always had a reputation for
being extremely resilient animals,

capable of surviving in small patches of forest.

This changed drastically in 2017,

when there was a wildlife epidemic of yellow fever

and its effects on them were devastating.

Of all the primate species, howlers were the most affected,

and some estimates in the state of Espírito Santo, for example,

suggest population losses of more than 90%.

It was important for us to develop a yellow fever vaccine

to use on howler monkeys,

because howler monkeys are the most
sensitive species to the virus.

The Tijuca Forest howler monkeys,

which were reintroduced after 2018,

are all vaccinated against yellow fever,

so that we can guarantee their survival

for at least their lifetime and

so that they can reproduce in the wild.

And now we’ve managed to release another
group of six individuals.

We hope that with these two groups in the forest,

that the individuals disperse from one group to the other.

This will increase the population’s genetic variability,

which is very important if it is to be
maintained in the long term.

So many of these animals that are found are sick

or are found seized from animal trafficking.

These animals were all brought together months
before the introduction,

at the Rio de Janeiro Primatology Center in Magé,

which is a Refauna partner.

This here is the acclimation enclosure

it’s where the howler monkeys stay after they
arrive here from the primatology center.

They stay here for a while to adapt to the new forest.

This is where they learn about
what rain feels like,

that there are other animals here,
about the sounds of the forest

and above all, what their food is.

When we release the animals we always
offer food supplementation,

while they explore the forest’s new resources.

So it’s a box that we put up in the tree

with commercial food

mixed in with forest food that they didn’t get to explore yet.

And one of the females we have released still uses the box a lot.

And it’s a way we have of monitoring her.

The capuchin monkeys discovered

the supplementation box last week and have been visiting here.

He’s just arrived.

Do you think she will face up to him?

Yeah, I think she’s got a very strong personality,

so I think she will.

Howlers are seed dispersers

for various plant species,

so they play a very important role.

When howlers were first reintroduced here in the forest in 2015,

in four years up to 2019 howler monkeys
had already been observed

consuming 60 different species of plants.

And naturally, they defecate a lot of seeds
from these species of plants.

When we’re following the howler monkeys

and we see them eating a leaf or fruit from a tree,

we mark the trunk with a pink ribbon

with a code and mark its location on the GPS,

and eventually we manage to get back here
and identify the species.

This is important to know which species they
are interacting with

and what interactions they are establishing in the forest

We also have some cameras scattered in the forest canopy

that sometimes manage to capture images of howler monkeys.

These reintroduction or rewilding programs,

especially in the Atlantic Forest, have
become increasingly important,

because we’re dealing with a forest that has suffered and

has undergone countless changes over the years

and which today survives as very fragmented areas.

I think it

could be a game changer for conservation.

The amount of goodwill

generated by a project like this is enormous.

And why is this?

Because it’s a positive agenda.

Because we’re bringing one of the things

that the world needs most at the moment…

Hope.