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Making room in the Atlantic Forest for the largest primate in the Americas

  • The destruction of Brazil’s Atlantic Forest has created countless isolated forest patches surrounded by pastures, cities or monoculture plantations, with serious consequences for northern muriquis, the largest primate in the Americas.
  • Considered critically threatened, northern muriquis depend on connectivity between different groups to survive; when females reach sexual maturity, they migrate to other groups, ensuring the species’ genetic diversity.
  • In Minas Gerais state, a pioneering project by the Muriqui Institute of Biodiversity and Comuna do Ibitipoca is working to rescue isolated muriquis, release them into a restored forest area, and create forest corridors to allow them to move around.
  • Conservationists say private landowners, such as Comuna do Ibitipoca, will be key to creating these corridors, given that 80% of the remaining patches of Atlantic Forest lie within private lands.

Alone in the woods for more than five years, Esmeralda wrapped her long arms around her own body in an attempt not to forget the feeling of a hug. Three hundred kilometers, nearly 190 miles, to the south, brothers Bertolino and Luna had only each other to exchange affection with and try to remember what it meant to be a northern muriqui, even though the absence of females seemed to signal the end of that small and isolated population in southern Minas Gerais state, Brazil. For the largest primate in the Americas, there’s nothing it can do against the habitat fragmentation that strangles its chances of survival.

It was 2017, and researchers from the Muriqui Institute of Biodiversity (MIB) were making a first and urgent attempt to gather those isolated northern muriquis, Brachyteles hypoxanthus, a species of woolly spider monkey. Esmeralda had lived alone for five years in a patch of the Atlantic Forest patch in the mining district of Esmeraldas de Ferro, until she was captured and translocated to the forest fragment of Mata do Luna, in the municipality of Santa Rita do Ibitipoca, where the two males were living. There was hope that the three individuals could interact and perhaps even begin to breed, but the years of solitude had taken too much of a toll on the female.

“Because she had been alone for five years, she had many social issues,” says Priscila Pereira, a researcher at the MIB. “For example, what the muriquis do in terms of sexual behavior, she used to do to horses because there were only horses where she came from.” Muriquis produce a kind of neigh, and perhaps the similarity of the sound contributed to Esmeralda’s confusion. Researchers saw this as a cruel sign of how deeply she had been disconnected from her own nature.

Oblivious to her peers, Esmeralda twice fled the Mata do Luna area. In her last escape, she disappeared completely. The researchers suspect she probably died in the midst of an outbreak of yellow fever. If so, it was a sad outcome, but one that spurred a pioneering initiative to save the species. In 2018, the Muriqui House was built, focused on resocializing the isolated monkeys to allow them to successfully reintegrate into nature. The facility is today home to five adult and two young northern muriquis.

The story that led to this promising home for muriquis begins much earlier, in the 1980s, with two events that were unconnected at first: the purchase of a farm by two cousins who wanted to “let nature regenerate” and which gave rise to the Comuna do Ibitipoca project; and the arrival of a U.S. researcher to rural Minas Gerais, seeking to observe the lives of these large New World primates up close.

Little Elliot, an infant muriqui born at Muriqui House. Image by Vitor Marigo.

The Research

Like most primates, northern muriquis depend on strong social relationships, living in groups of up to 60 individuals. They’re found in the Atlantic Forest in Brazil, live high in the canopy, where they move nimbly from branch to branch, feeding on fruit, flowers and lots of leaves. Yet all of these traits, so characteristic of apes, hide a very particular behavioral ecology.

“Muriquis are totally calm; they have no hierarchy,” says primatologist Karen Strier, who recalls how the extremely peaceful behavior of the muriquis caught her attention from the beginning.

Strier is currently a professor at the University of Wisconsin-Madison and research director of Instituto Preserve Muriqui, which manages the Feliciano Miguel Abdala Private Natural Heritage Reserve (RPPN by its Portuguese acronym) in Caratinga, Minas Gerais. In June 1982, she was just 23 years old when she set foot on Brazilian soil for the first time and came face to face with the largest primate in the Western Hemisphere.

Karen Strier on her first visit to the farm in 1982.
Karen Strier in 1984.

“My interest was to test theories of social evolution in a [primate] species that had not been studied very precisely yet,” Strier says in good Portuguese with a strong English accent. Until the 1980s, howler monkeys (Alouatta spp.) were the only New World primates whose social behavior had been studied in detail.

Strier began the first in-depth study of a population of muriquis, which today allows us to know the particularities of the species in some detail. In most primate species, males tend to be larger than females, both in terms of overall body size and canine teeth, one of their main weapons. Probably because of this advantage, males in the primate world usually display dominant behavior over females. In northern muriquis, however, both sexes are the same size, which means the females aren’t easily coerced or controlled.

One of the first things Strier realized, and which she considers her most important finding, is that there’s no hierarchy or aggression between sexes in the world of the muriquis. There’s not even aggression within the same sex. Northern muriquis do have small fights, but they’re surprisingly peaceful and affectionate creatures. For example, they often touch and hold each other for long periods just to show affection.

Strier also notes that the females are responsible for the species’ genetic diversity. Near reproductive age, between 5 and 7 years old, they leave their native groups in search of new families and, consequently, in search of partners that are not so closely related, which guarantees varied genes for new generations. While this movement is positive from a genetic point of view, it has serious implications for the conservation of muriquis: for groups of these primates, geographic isolation is a death sentence.

The fate of northern muriquis is intrinsically linked to that of the Atlantic Forest, as the species is endemic to the biome; that is, it’s found nowhere else on Earth. This has made muriquis one of the many victims of centuries of forest destruction along the Brazilian coast. Today, there are an estimated 1,000 northern muriquis in the wild, spread across 12 locations. Only in five of them is the number of individuals considered sufficient for them to have a good chance of survival in the long term.

In this scenario, the females’ departure from isolated muriqui groups — a natural and necessary aspect for their ecology in healthy conditions — becomes a problem. They abandon their group before having any offspring and go in search of other groups, but habitat fragmentation and the great distance between populations may condemn females to a wandering and solitary life. That’s what happened to Esmeralda.

The tragic fate of these females is also a bad omen for their native groups, which, due to the same distance and landscape fragmentation, miss out on the arrival of females from other groups, and gradually decline.

As Strier was conducting her pioneering study in the Feliciano Miguel Abdala RPPN, the small and unknown group of northern muriquis that inhabited Mata do Luna faced exactly that problem.

By chance, Mata do Luna survived intact the economic cycles of coffee and livestock farming in the Minas Gerais region known as Zona da Mata, and a small fragment of primary forest was preserved. Despite being less than 3 km (1.9 mi) north of the boundary of Ibitipoca State Park, Mata do Luna was completely isolated by livestock pasture, effectively acting as an open-air prison for the muriquis, which had nowhere else to go.

In 2000, reports from residents led MIB researchers to the forest fragment, where they confirmed the presence of 10 northern muriquis. Seven years later, only two individuals remained: brothers Bertolino and Luna. The latter had never even lived with females since reaching sexual maturity, and therefore never learned how to copulate — another social consequence of isolation.

When businessman Renato Machado learned in 2000 of the presence of northern muriquis in Mata do Luna, he decided to act. First, he bought the forest area where the animals were living, and then the surrounding lands. Machado is the creator of a growing high-end hotel development called Comuna do Ibitipoca, which also invests in regeneration of natural areas in the region. The development began in 1984, with the purchase of the Engenho farm, and now covers nearly 6,000 hectares (14,800 acres) — four times the size of the neighboring Ibitipoca State Park.

Comuna do Ibitipoca’s mission, Machado says, is to allocate 98% of the land he purchased to recovery and occupy only 2% with hotel facilities. In the “pristine” portion of Comuna do Ibitipoca, their goal is to have another type of guest: native wildlife.

One of the old farms bought by Comuna do Ibitipoca, which today operates as a hotel. Image by Vitor Marigo.

Mata do Luna is a good example. After buying it at the turn of the millennium, when it was an isolated fragment of less than 35 hectares (86 acres), Comuna do Ibitipoca invested in the purchase of pastures that surrounded the forest. Twenty years later, about 200 hectares (nearly 500 acres) in the Mata do Luna area are undergoing regeneration.

“We buy them, then we remove the cattle and protect it from fire,” Machado says. From then on, nature itself does the work of restoring the area with vegetation, little by little. In places where degradation was more serious, however, Machado says he recognizes the need for human intervention through planting. “It’s a long-term project,” he adds.

While Mata do Luna is on its way to restoration, for muriquis Luna and Bertolino, time was running out. In 2017, the brothers were the last survivors in the forest fragment, and after the unsuccessful attempt to integrate Esmeralda, it became evident to both biologists and Comuna do Ibitipoca staff that a stronger management intervention was needed so that the population of muriquis in the Ibitipoca region could have a chance. That is when the Muriqui House project was born.

Bertolino, the oldest male in the group. Image by Vitor Marigo.

A home to resocialize the largest primate in the Americas

The land where Muriqui House was built sits in Vila do Mogol, in the district of Conceição de Ibitipoca, and looks nothing like a typical captivity facility. The 6-hectare (15-acre) lot is ringed by a low-intensity electric fence, which prevents the muriquis from escaping. Inside, a concentration of trees on 2 hectares (5 acres) — some 3,000 trees planted by the project staff — provide the food that the muriquis need.

In addition to the small forest, which has feeding platforms and service trails, the area also has a large caged enclosure where the animals are kept for quarantine and acclimatization, and a small house that serves as the headquarters for MIB researchers. A calendar on the wall marks out important cycles that are monitored, such as when the females go into heat, and when reproductive activity occurs among the muriquis.

The Muriqui Institute of Biodiversity was created in 2015 to support and carry out actions for the conservation of ecosystems and biodiversity, especially those affecting muriquis and their habitat. In 2016, the NGO started a partnership with Comuna do Ibitipoca, initially focused on monitoring the muriquis in the Mata do Luna region. As the work evolved and investment was needed for resocializing the primates to guarantee their survival, Comuna do Ibitipoca saw the need for the Muriqui House, and invested around 1 million reais ($211,000) to build the facility.

Muriquis are agile and move gracefully through the trees. Image by Vitor Marigo.

In 2019, the first northern muriquis arrived. Two females, Ecológica and Socorro, came from the Mata do Sossego RPPN, a fragment of Atlantic Forest located about 400 km [250 mi] north in Minas Gerais. The two were chosen because they were of migrating age and had nowhere to go. Brothers Bertolino and Luna were also brought in.

In November 2020, another female, Nena, joined them. Later that month, the group grew with the arrival of Elliot, the offspring of Ecológica and Bertolino, and the first northern muriqui born in captivity.

In late 2021, another individual joined the Muriqui House group. Three-year-old Odin was found in the municipality of Caratinga, alone and weak. After about a month of rehabilitation at a wildlife screening center in Belo Horizonte, the Minas Gerais state capital, experts from the National Action Plan (PAN) for the Conservation of Atlantic Forest Primates and the Collared Sloth (PANPPMA) decided that the best option was to send him to the enclosure at Comuna do Ibitipoca.

“If we want to protect the muriquis, we have to do management,” says MIB researcher Fabiano Melo, a primatologist and professor at the Federal University of Viçosa (UFV).

With seven individuals, Muriqui House is today the only captive facility that manages northern muriqui individuals and the closest to natural conditions that these primates have. As good as it is, it’s not intended to be a permanent place, but rather a vital step for all animals living there to return to nature in sustainable conditions — that is, in a situation where their groups can thrive and grow. And “groups,” in the plural, are just what is needed.

For northern muriquis to once again have a future in the Ibitipoca area, two different groups of individuals must coexist at a close and connected distance. Then, females will be able to migrate between the groups and guarantee the existence of the local muriqui population as a whole. That’s how the northern muriquis studied by Strier at the Feliciano Miguel Abdala RPPN were able to survive. In the early 1980s, the RPPN was home to two muriqui groups, which used to exchange females every generation. Today, five groups of muriquis live in the region.

The MIB researchers plan to gather enough individuals at Muriqui House to release at least two groups of 10-12 individuals each in Mata do Luna. And everything indicates that they will hit their target. In the region of Peçanha, also in Minas Gerais, a group of muriquis faces a situation similar to that experienced by the individuals of Mata do Luna a few decades ago.

“I see Peçanha as the most critical scenario today,” Melo says. “It’s a small group of 15 individuals totally isolated in a 500-hectare [1,240-acre] forest area.” Without any intervention, this group would also slowly decline. So the MIB’s plan is to gradually capture the individuals from Peçanha, integrate them into the Muriqui House group, and form the groups needed to make the Ibitipoca area a home for northern muriquis once again.

“Machado’s dream is to have 500 muriquis here in 50 years,” Melo says, recalling a conversation he had with the Comuna de Ibitipoca founder years ago. “We got off to a good start. Within 40 years I think we won’t have 500 yet, but we can easily have 100 muriquis here.”

The conservation of northern muriquis

With an estimated population of fewer than 1,000 individuals, the northern muriqui is considered critically Threatened on the IUCN Red List, with the main threat to the species being the fragmentation and loss of its habitat. Known northern muriqui populations are distributed across 12 areas, starting on the state border between Rio de Janeiro and Minas Gerais, in Itatiaia National Park, and sprinkled across Minas Gerais and into Espírito Santo and southern Bahia, in the Upper Cariri complex.

Five of those 12 areas are listed as priorities for the conservation of the species, according to an assessment by the National Action Plan for the Conservation of Muriquis, or PAN Muriquis, which ended in 2015. These sites have the largest known populations of northern muriquis, with more than 100 individuals each. They’re locates in the Feliciano Miguel Abdala RPPN, in Rio Doce State Park, and Serra do Brigadeiro State Park, all in Minas Gerais; a series of fragments of varied sizes in the region of Santa Maria de Jetibá, in Espírito Santo; and Caparaó National Park, on the border between the two states. Currently disconnected, these forest fragments are 70-120 km (40-75 mi) away from their nearest neighbors. For the most part, they’re separated by a patchwork of forest fragments and rural properties.

The regions with the most threatened populations include Ibitipoca (now being made safer thanks to Muriqui House) and Peçanha (which wasn’t even included in the original national action plan, as only officially confirmed in 2020). Both are on the list of management priorities for the MIB team.

Face depigmentation is one of the features that distinguish northern muriquis from their southern relatives. Image by Vitor Marigo.

The first cycle of the muriqui national action plan ran from 2010-2015, the result of the work of the first international committee organized for the conservation and management of the species, and was extended for another two years. The general goal of the action plan was to improve the conservation status of the species by at least one level on the IUCN Red List, from critically endangered to endangered. To this end, the plan set out 10 specific goals and 58 actions to achieve its ultimate target. Officially completed in 2017, 46% of the actions provided for in the PAN were fully implemented, while the other 54% saw some form of progress.

In 2018, the PAN Muriquis was replaced by the National Action Plan for Atlantic Forest Primates and Collared Sloth (PPMA), scheduled to end in 2023. These plans were essential for bringing together several actors interested in the conservation of muriquis and enabled the organization of vital workshops and meetings. One of them took place in 2020 at Comuna do Ibitipoca, gathering researchers such as Melo (a member of the PAN Technical Advisory Group) and managers and agents from agencies such as the National Center for Research and Conservation of Brazilian Primates (CPB), one of the arms of ICMBio.

“We brought in the members of the CPB, the Brazilian agency in charge of these issues related to [primate] fauna, and through a discussion we consolidated a formal, protocolized management strategy that describes what we should do when we find an isolated female, an isolated male, an isolated group of males or females, or an isolated mixed group,” Melo says. “So today, we know exactly what we have to do,” he adds, referring to the document “Protocols for Research and Management of Muriquis,” written by 31 experts and published in October 2021.

The protocol details all the tools necessary for the conservation of muriquis, ranging from managing the animals themselves to measures for assessing habitat quality — an essential tool for establishing future corridors.

“We have an ambitious project to establish corridors between Brigadeiro, Caparaó, Sossego and Caratinga,” Melo says. “We are looking for national and international funders. We want to start by connecting Caratinga and Sossego, which would be a 45-kilometer-long [28-mile] corridor and is already partially established as a result of legal reserve forest areas and PPAs [permanent preservation areas].” The money would be used to encourage rural landowners to reforest the areas needed to connect the reserves.

“There is even a state executive order [397/2014] that establishes the Caratinga-Sossego ecological corridor,” Melo adds. “The state itself assumed the responsibility of helping research institutions and local landowners to implement a corridor, benefiting these two populations of muriquis. It will still take a few decades for us to see muriquis passing from one side to the other in these corridors, but we are working on that.” The corridor interconnecting private reserves covers a combined 66,400 hectares (164,100 acres) across seven municipalities in Minas Gerais.

These corridors connecting muriqui populations are not the only ones planned for the region. “We want to join Mogol and Serra Negra,” says Beto Nardelli, director of biodiversity and culture at Comuna do Ibitipoca. The project aims to establish a 25-kilometer (16-mile) ecological corridor between Ibitipoca and Serra Negra state parks through Vila do Mogol, where one of the headquarters of Comuna do Ibitipoca is located. The biggest challenge, Nardelli says, is precisely the connection between Serra Negra and Mogol, as the Comuna area itself forms a corridor with Ibitipoca State Park.

Between the two forest massifs lies a mosaic of livestock pasture and forest fragments, which can serve as a basis to establish the corridor. “And we will also have to restore, of course,” says Nardelli, who plans to take advantage of the ranches’ legal requirement to reserve some forested area (known as the legal reserve) to facilitate the restoration plan.

He says he believes the corridor should promote not only environmental but also economic revitalization in the region. “We need to think about the corridor more broadly, within a socioeconomic context in which the population can enjoy a new economy, because if it’s only good for nature and not good for people, it will be more difficult for the initiative to succeed,” Nardelli says.

While there is no known population of muriquis in Serra Negra State Park, researchers hold out hope that there may still be a group clinging on in the area, which covers more than 13,000 hectares (32,100 acres) and has many areas that are difficult to access. “We have reports of muriquis there, and there have been helicopter overflights, land incursions, use of playback, but they have not been able to prove the existence of that population so far,” Melo says. “A primatologist heard a muriqui neigh there in 2016. So there may still be a small relict population, but it’s a needle in a haystack.”

To fully comb the Serra Negra canopy, the researchers plan more excursions to the park with special help. The “dronequi,” a drone nicknamed after its main function of finding muriquis, was born in 2017 from a fortuitous combination of creativity, necessity and technology, when Melo decided to equip a drone with a hybrid photographic and thermal camera.

The tool is one of the MIB team’s secret weapons to map hard-to-reach forest areas and identify the presence of muriquis. “The Serra Negra area is big; we’ll have to scratch it and fly the drone, but if there’s a muriqui there, we’ll find it,” Melo says.

The first version of the “dronequi,” with the camera attached. Image by the Muriqui Institute of Biodiversity (MIB).
For version 2.0, the “dronequi” became more compact and powerful. Image by the Muriqui Institute of Biodiversity (MIB).

Comuna do Ibitipoca’s rewilding dream

In addition to the project with the northern muriquis, Comuna do Ibitipoca is also investing in the management and recovery of other native wildlife species. Currently, the group has three tapirs (Tapirus terrestris) authorized by the Minas Gerais State Forest Institute (IEF-MG), which will be the first ones to recolonize the region, where the species is locally extinct. It’s doing the same with a group of 25 black-fronted piping guans (Aburria jacutinga), a bird species that it has already released and is now monitoring.

In another partnership with the IEF-MG, Comuna do Ibitipoca also promotes the release of purple-breasted parrots (Amazona vinacea) to strengthen the species’ local population. Red-and-green macaws (Ara chloropterus) and solitary tinamous (Tinamus solitarius) are also in the plans, with the release of each bird species at different stages in the process of authorization by the environmental agency.

On a more distant horizon, Machado’s personal dream is to be able to bring the largest Brazilian bird of prey, the harpy eagle (Harpia harpyja), back to the skies of Ibitipoca. For this, he predicts the current area of approximately 6,000 hectares (14,800 acres) of Comuna de Ibitipoca will have to be expanded several times over. “20,000 hectares [50,000 acres]?” we ask him. “Ideally, we should have a little more, right? About 30,000 (74,000 acres),” Machado replies in a confident tone and a smile.

Vila do Mogol, the headquarters of Comuna do Ibitipoca, in Minas Gerais. Image by Vitor Marigo.

The role of private areas

Whether it’s in the Feliciano Miguel Abdala Private Natural Heritage Reserve, where Karen Strier began her research and conservation project for northern muriquis, or in Comuna do Ibitipoca, private properties now play a key role in protecting the largest primate in the New World. The same goes for the fate of other species of wildlife native to the Atlantic Forest. The group SOS Mata Atlântica estimates that 80% of the remaining patches of Atlantic Forest lie within private lands.

RPPNs, the only category of conservation unit under private management, are a key option for guaranteeing the protection of what’s left of the forest. In addition, land converted to RPPN obtain perennial title; that is, they may be sold and may change ownership, but they will remain protected areas forever.

There are currently 1,268 private reserves covering more than 230,000 hectares (568,000 acres) in the Atlantic Forest, according to data from the National Confederation of RPPNs (CNRPPN) panel. Of these, 245 are located in Minas Gerais, amounting to about 40,000 hectares (99,000 acres) of protected Atlantic Forest on private land.

The Minas Gerais state government, however, doesn’t have any specific program or policy to promote the creation of reserves. The only formal incentive is exemption from the rural territorial property tax, or ITR (which varies according to land size and use), of the area converted into a reserve.

“Most RPPNs in the Atlantic Forest belong to private individuals and most are very small, but in Minas Gerais there are a lot of corporate-owned RPPNs maintained by companies,” says Maria Cristina Weyland Vieira, president of the Association of RPPNs and Other Private Reserves of Minas Gerais (ARPEMG). “But the vast majority of RPPNs in Brazil don’t have their own [financial] sustainability; their maintenance depends on their owners, whether they are individuals or legal entities,” she adds.

The expenses for an RPPN owner may include fencing the area to prevent neighbors’ cattle from entering and trampling on a regenerating area, or funding a fire brigade and a ranger group. “Owners can’t afford that,” Weyland Vieira says. “In most small RPPNs, the owners don’t have that money. There are partnerships. It’s important to establish partnerships or find sponsorships.”

She says one resource that municipal governments can use to encourage the creation of RPPNs and support landowners is the transfer of part of the ecological state sales tax (ICMS) to owners, since the amount received by municipalities is based on a series of criteria, including the existence of protected areas.

Despite being a private area mostly focused on recovery and conservation of nature, Comuna do Ibitipoca is not an RPPN. Machado is emphatic in explaining why: “It limits everything.” He says that in order to guarantee investments in conservation, there must first be an economically viable business — something that would be much more difficult to achieve under the red tape of an RPPN.

Muriqui-watching tours, for example, are something that Machado is betting on. He notes that similar tours centered around other birds and jaguars already generate huge revenue. At Comuna do Ibitipoca, guests can already visit Muriqui House accompanied by MIB staff. At the end of the tour, they’re invited to donate to the project. “Everyone is so delighted with the muriquis that they always donate,” Melo says.

What remains of the Atlantic Forest today doesn’t depend only on public officials for its conservation — the people who share ownership of the 80% of the biome that are on private lands have decision-making power over its future. Many of these stakeholders, such as those at Comuna do Ibitipoca and the Feliciano Miguel Abdala RPPN, have done more than their share in defending northern muriquis and the forest they inhabit. The history of destruction in the Atlantic Forest has trapped the largest primate in the Americas in small fragments, leaving them without the large and cohesive forest they need. But muriquis themselves can promote the restoration of their home. In the end, defending the muriquis means protecting the Atlantic Forest, and vice versa.

Banner image of a northern muriqui by Vitor Marigo.

This story was reported by ((o))eco and first published here in Portuguese on Feb. 1, 2022.