How Brazil is working to save the rare lion tamarins of the Atlantic Forest

The Atlantic Forest that hugs the coast of Brazil is home to four small primates found nowhere else on Earth. The most famous of them, the golden lion tamarin, appears on Brazil’s 20-real bill, a part of the day-to-day interactions of people across the country. But not everyone knows the primate’s conservation story, which began in the 1960s and saw it saved from likely extinction through years of challenging work. Its lesser-known but equally charismatic cousins have similar tales of narrowly avoiding extinction, all of which have unfolded in the Atlantic Forest, Brazil’s most devastated and fragmented biome.

For five months, ((o))eco’s reporters interviewed researchers who work, or have worked, to protect the four small primates belonging to the genus Leontopithecus, the lion tamarins. In the Darwinian lottery, these species emerged winners with their distinctive color schemes that led to their popular names: fully golden (golden lion tamarin, Leontopithecus rosalia), fully black (black lion tamarin, Leontopithecus chrysopygus), black with a golden face (golden-headed lion tamarin, Leontopithecus chrysomelas), and golden with a black face (black-faced lion tamarin, Leontopithecus caissara). The species are distributed, respectively, in the states of Rio de Janeiro, São Paulo, southern Bahia, and in the border region between Paraná and São Paulo. Aside from having similar appearances, sizes and habits, the four tamarins have also been similarly affected by the destruction of their habitat, the Atlantic Forest. The fates of at least three of the tamarins was altered due to the special work of Adelmar Faria Coimbra-Filho (1924-2016), considered the father of Brazilian primatology.

“The golden lion tamarin was [first described] by the naturalist Johann Natterer, a famous Austrian scientist who visited Brazil at the beginning of the 19^th century, when he found the [golden] lion tamarins in Guaratiba,” on the western outskirts of the city of Rio de Janeiro,” Coimbra-Filho said in 2004. “In 1942, I again found two or three tamarins at a hunting ranch [there].”

It was at the ranch where Coimbra-Filho first saw lion tamarins in the wild, and where he was inspired to study them. He began spending time in the forest, noting the places they lived, studying the sparse literature that existed at the time, and mapping their areas of occurrence. When he was fired from this job at the old Gávea Park in Rio de Janeiro and sent to work at the city’s zoo, taking on the role of head of technical and scientific services, his passion became an object of study.

“[Working at the zoo] gave me the opportunity me to work with a broad range of animals, which was very good,” Coimbra-Filho said in a 2005 interview. “That’s where I began to get interested in primatology. But it wasn’t because of the zoo when I worked with chimpanzees, orangutans and a variety of Brazilian and African tamarins. Rather it was because in the past I had seen a tiny tamarin, the golden lion tamarin, which I thought was extraordinary.”

In the early 1960s, Coimbra-Filho was the technical adviser at the Jacarepaguá Biological Reserve (now defunct), where he created an experimental center on the site with agronomist Alceo Magnanini to create the first golden lion tamarin release program for animals in captivity. “It didn’t work because the reserve was consumed by the urban expansion of Rio de Janeiro,” he said in a 2004 interview with ((o))eco.

In 1969, by then a veteran in the study of the golden lion tamarin, Coimbra-Filho went to southeastern Bahia state to study its cousin, the golden-headed lion tamarin, in its natural habitat. He had worked with the animals in captivity for years, but he wanted to find an area that could be dedicated to its preservation. A few years later, in 1973, he found a well-preserved patch of forest inside the range of the golden-headed primate in the municipality of Una. It became the Una Biological Reserve in 1980.

The 1960s and ’70s are considered the golden age of primatology in Brazil, home to the largest number of primate species in the world. Numerous studies were published during this period, national and international partnerships were formed, and the Brazilian species gained visibility. The lion tamarins were the superstars of this era.

The rediscovery of the black lion tamarin in 1970, which had until then been considered extinct, earned Brazil and the man who rediscovered it — Coimbra-Filho — international acclaim. The discovery happened after another primatologist, Álvaro Aguirre, came upon a pair of stuffed black lion tamarins, a species not seen since 1905, in a gun shop in the small inland town of Presidente Venceslau, São Paulo state.

“When that happened [in 1970], Coimbra-Filho decided to visit the gun shop and see for himself,” said Claudio Valladares-Padua, a biologist who worked with Coimbra-Filho, including on the founding of the Ecological Research Institute (IPÊ), which today works on the conservation of the black lion tamarin. “He then searched the region for a patch of forest and identified an area on the map that would later become Morro do Diabo State Park. He went there and found [the tamarins].”

Adelmar Coimbra-Filho studied three lion tamarin species (not the black-faced lion tamarin, though, as it was only described in 1990) and helped push through public policies for their protection. These include a gene bank, captive-breeding program, and the creation of or funding for conservation units to maintain the habitats of viable populations.

The life and work of Adelmar Coimbra-Filho is one of the threads that connects the lion tamarins. Another is the Atlantic Forest biome. In one way or another, all the lion tamarin species have been affected by the centuries of destruction of the biome and the obstacles this has created to their survival. The four tamarins’ fight for their lives is a fight for the conservation of the Atlantic Forest.

“Tamarins are forest creatures, as are tapirs and jaguars, even though they can travel long distances through lower vegetation,” said Alcides Pissinatti, a veterinarian who heads the Rio de Janeiro Primatology Center (CPRJ). “The only way to get these animals back and maintain their populations is to restore what can be restored of the Atlantic Forest.”

A participant in the first attempt to return golden lion tamarins to nature, Pissinatti said the strategy of preserving areas for the purpose of species conservation in the wild was something Coimbra-Filho had been trying to do since the early 1960s. This led to the creation of several conservation units in the state of Rio de Janeiro, such as the Poço das Antas Biological Reserve (created in 1974), an area that was home to one of the largest golden lion tamarin populations at that time.

Golden lion tamarin: Stuck in patches of forest

Of these four species of maned primates, the golden lion tamarin (Leontopithecus rosalia) is the best-known and the first to be formally described by Western science. The first documented record of the tamarin was made by Antonio Pigafetta, an Italian chronicler on the 1519 expedition by Fernão Magalhães (known in the English-speaking world as Ferdinand Magellan) that was the first to circle the globe. Over the following centuries, the golden lion tamarin caught the attention of other Europeans — including Charles Darwin, on his way through Rio de Janeiro — and the primate, deemed “exotic” in the Old World, appeared in many paintings of the period. This also meant that, since their introduction to the wider world, the tamarins have been objects of consumption and importation — wildlife trafficking, essentially.

Hunting, trafficking and destruction of the coastal Atlantic Forest in Rio de Janeiro state, the golden lion tamarin’s only habitat, reduced the species’ distribution, which originally extended along the coast until the city of Rio de Janeiro. Today, the tamarin’s largest population lives in forest fragments in the São João River Basin between the municipalities of Silva Jardim, Casimiro de Abreu and Rio Bonito and five other towns in the area.

Fortunately for the golden lion tamarin, its path crossed that of Adelmar Coimbra-Filho. As a result, even the destiny of Rio de Janeiro’s remnants of Atlantic Forest took a turn. In 1969, one of Coimbra-Filho’s first population estimates came up to about 600 golden tamarins living in the wild. Four years later, in a count done together with U.S. primatologist Russel Mittermeier, that number had fallen to 400. And in a subsequent survey, in 1977, they realized a mere 100-200 golden lion tamarins were left in the wild, and sounded the alarm that the species was nearing extinction.

After more than 50 years and several projects to reintroduce animals bred in captivity into the wild, the golden lion tamarin’s situation has changed radically.

The Poço das Antas and União biological reserves were created within the tamarin habitat in 1974 and 1998, respectively. And more than 25 private natural heritage reserves (RPPN in Portuguese) were created, including the São João River Basin/Golden Lion Tamarin Environmental Protection Area for sustainable use in  2002. That same year, Três Picos State Park was also created.

All these conservation units have helped guarantee the presence of protected islands of Atlantic Forest, thereby protecting the tamarins’ home. Today, the greatest challenge in guaranteeing the species’ survival is connectivity between the forest fragments — or rather, the lack of it.

“It’s always good to remember that we are talking about a forested mountainous region, but the golden lion tamarin only lives at altitudes over 500 meters [1,640 feet],” said Luís Paulo Ferraz, executive secretary of the Golden Lion Tamarin Association (AMLD, in Portuguese). “At lower altitudes, we have the severe problem of fragmented habitat. There is little forest and that which we still have is very fragmented.”

The AMLD was created in 1992 to centralize and consolidate golden lion tamarin conservation efforts. Headquartered in the municipalities of Casimiro de Abreu and Silva Jardim, the association prioritizes the so-called conservation landscape method: saving areas that are seen as the most viable for consolidating the species’ survival in the long term.

A population and habitat viability assessment (PHVA) indicates that for the endangered tamarins to avoid extinction and still be around 100 years from now, while also retaining at least 98% of their genetic biodiversity, there needs to be at least 2,000 tamarins living across 25,000 hectares (62,000 acres) of protected — and connected — forests by 2025.

“We’ve had 2,000 tamarins for a long time, and today we have over 25,000 hectares of forest,” Ferraz said. “Our current problem is in connecting them. It doesn’t help to have 10,000 tamarins living in isolated fragments. In order to ensure genetically viable groups, there needs to be genetic exchange between them, and that only happens with connection. They will not cross pasture to get from one forested area to another.”

The obstacles are varied, ranging from pastureland to urban areas, railroads to power lines, and gas lines to oil pipelines.

When the lion tamarins reach 2 years of age (their life span is 15 years), they leave or are kicked out of their groups. When this happens, the young primate goes on alone, vulnerable to predators, until it finds a mate and a corner of the forest to call its own.

A golden lion tamarin’s range is about 50 hectares (125 acres) and the bands are very territorial, fighting each other to defend their areas. When a solitary tamarin enters territory already established by a group, it will be promptly driven away. And if this happens in an isolated forest fragment, it may be forced to descend to the forest floor — a rare and unpleasant event in the life of a tamarin.

“If they are being kicked out of that particular area of forest by another group and have nowhere to go, they will try to cross streets or highways to try and reach forest on the other side. Oftentimes they are run over,” said biologist Andréia Martins, who has worked with lion tamarin management since 1983. Even though there’s no system for collecting data on roadkill, the AMLD has records of at least six tamarins that were killed this way, a clear sign of the desperation experienced by an exclusively tree-living species forced to cross asphalt because its habitat has been carved up.

The largest block of continuous forest remaining today is divided between the União Biological Reserve and the Aldeia Velha area of Silva Jardim municipality. It spans around 20,000 hectares (nearly 50,000 acres) and is home to some 1,100 tamarins. Three years away from the target date for connecting 25,000 hectares of forest, the scenario is still challenging, but promising. One recent victory was the construction of a vegetation-covered viaduct enabling wildlife to cross the four-lane BR-101 freeway, one of the region’s main barriers.

Tamarin bridge

One of the largest remaining isolated golden lion tamarin habitats is the Poço das Antas Biological Reserve, the first to be established in Brazil, in 1974. It was created specifically to safeguard the habitat of the lion tamarin and the maned sloth (Bradypus torquatus).

The approximately 5,000 hectares (12,400 acres) of Atlantic Forest inside the reserve, classified at the highest level of protection, are a green island in the midst of pastureland and farms. Its northern edge is marked abruptly by the heavily trafficked BR-101 highway — a practically uncrossable barrier for many animals, especially those that live and move in the treetops.

When the BR-101 was widened, another struggle ensued: pressure on the highway concession operator, a company called Arteris Autopista Fluminense, to meet the environmental mitigation requirements detailed in the project’s environmental license. Among them is the construction of 10 treetop-to-treetop passageways, 15 underground tunnels, and one vegetation-covered viaduct to connect the Poço das Antas reserve with the other side of the freeway, where the AMLD bought a farm that today houses the association and that’s being planned for a future Golden Lion Tamarin Ecological Park.

After a lengthy legal struggle, also involving the Federal Prosecutor’s Office, the mitigation plans got off the drawing board. In August 2020, the planted bridge was finally inaugurated, the largest of the wildlife passage structures, built at a cost of 9 million reais ($1.9 million). For the tamarins, however, true connectivity, is still out of reach, as they depend on trees to get from one place to another, and the seedlings planted on the bridge won’t be big enough for them for a few years. The treetop-to-treetop bridges and tunnels have also been completed.

Threat of yellow fever

Already enjoying a stable phase in their recovery, the golden lion tamarin’s growing population faced a new challenge in 2017: yellow fever. A new outbreak of the disease reduced the species’ population from 3,700 to 2,500. The loss of 1,200 individuals, nearly a third of their total population, raised a red flag over the species’ continued vulnerability.

The situation was particularly dire in the Poço das Antas Biological Reserve, where the tamarin population was nearly decimated. Only 33 of the 380 tamarins that lived in the reserve survived.

“We know what needs to be done to save the species. Still, the yellow fever epidemic showed us that they are still very vulnerable, especially with a small population in a restricted area. We could have lost them all,” said Ferraz from the AMLD.

The solution to beating the disease was clear: immunize the primates — both human and non-human. The yellow fever vaccine has been available to humans for more than 80 years now, but it wasn’t an option for the tamarins back in 2017.

Vaccinating wild animals can be a controversial issue because it interferes with the natural cycle of viruses and parasites. Due to the golden lion tamarin’s vulnerability to disease and the species’ elevated risk of disappearing from nature if a new outbreak were to take place, the researchers arrived at a consensus: a safety population should be vaccinated to guarantee at least enough survivors to restart conservation efforts in the event of a new outbreak.

The vaccine was developed by Marcos Freire, a researcher at the Oswaldo Cruz Foundation, Brazil’s leading biomedical research institute, with funding from the Rio de Janeiro Primatology Center, or CPRJ. Testing was carried out on the golden lion tamarin’s cousin, the golden-headed lion tamarin. The captive population of this latter species had built up over the years, with no chance of reintroducing them into the wild. As all the lion tamarins share a similar biology, the vaccine developed for the golden-headed lion tamarin was effective for both.

The pioneering golden lion tamarin vaccination campaign began in November 2020, with the objective of vaccinating at least 400 tamarins by the end of 2022. As of today, some 200 of the primates have gotten the jab.

With the exception of the golden-headed lion tamarins living in captivity at the CPRJ, the golden lion tamarin is the first non-human species in the world to be vaccinated against yellow fever.

Black lion tamarin: Forgotten, found, isolated

The rediscovery of the black lion tamarin (Leontopithecus chrysopygus), a species native to the Atlantic Forest in the state of São Paulo that had not appeared in scientific records since 1905, helped earn a definitive place for Adelmar Coimbra-Filho in the pantheon of Brazilian and global primatology.

Sightings of the tamarin, described for the first time in 1823, grew increasingly rare as more of its forest habitat was leveled. In 1905, a male was collected and donated to the Museu Paulista by Olavo Hummel, head of one of the scientific expeditions of the São Paulo State Geographic and Geologic Commission. The institution already had three specimens of black lion tamarins in its collection at the time. From that point on, 65 years would pass before the animal was sighted again, leading people to believe that it had become extinct during that period. Finally, primatologist Álvaro Aguirre came upon two stuffed samples in a shop and called Coimbra-Filho in Rio de Janeiro, who specialized in two other lion tamarin species: the golden and golden-headed lion tamarins.

“The black lion tamarins had been forgotten until then. This discovery brought Coimbra-Filho international fame,” said Claudio Valladares-Padua, who worked as a primatologist at the State Environmental Engineering Foundation (FEEMA, now defunct) from 1980 to 1984. Three years after the rediscovery, Coimbra-Filho got authorization from the Brazilian Forest Service to remove seven of the animals from the wild and send them to the Tijuca Biological Bank. This marked the start of the captive management of the species.

A stone in the path of the black tamarin

As the state of São Paulo grew, so did its need for electricity. To meet this demand, hydroelectric dams were planned in the far west of the state in the 1980s, smack in the heart of the black lion tamarin’s range. At the time, scientist José Goldenberg was president of São Paulo’s state power company, the Companhia Energética de São Paulo (CESP). He hired an agronomist, Maria Tereza Jorge Pádua, to work in the agency’s Department of the Environment and Natural Resources. Pádua had recently quit her job as director of the parks department at the Brazilian Institute of Forestry Development (IBDF) after the government decided to build a road through the middle of Araguaia National Park.

“The hydropower projects where already underway when I arrived at CESP. What I did was to communicate to Goldenberg that one of the areas was home to black lion tamarins,” Pádua said.

The solution, a pioneering one for its time, was to set up a working group so the dam wouldn’t completely compromise the tamarin’s habitat and the survival of the species. Pádua credited Goldenberg’s scientific sensibility — he not only didn’t oppose the move, but also created no budgeting challenges for it — as well as the engineers from São Paulo whom she says were “serious people,” and Coimbra-Filho, who led the group. “He was involved at all levels, the most specialized, without a doubt.”

“It may have been the first environmental compensation initiative,” Cláudio Valladares-Padua said of that episode. At the same time, Pádua, a member of Coimbra-Filho’s team studying the tamarins that would be affected by the dam, decided to do her master’s degree on conservation of the black lion tamarin.

Studies on the species flourished as a result of the Rosana hydroelectric plant project, and drove forward a plan to transform the Morro do Diabo region, which had been a reserve on paper since 1941, into a conservation unit. In 1986, the 33,000-hectare (81,500-acre) Morro do Diabo State Park was created. Sixteen years later, in 2002, another 6,600 hectares (16,300 acres) received protected status. These were distributed between four fragments forming the Black Lion Tamarin Ecological Station: Santa Maria, Água Sumida, Ponte Branca and Tucano.

Of these four fragments, today there are black tamarins only in the Ponte Branca section. The population that had once been recorded in the Tucano fragment has disappeared; neither of the other two fragments held any tamarins. Ecological corridors are the best bet to interconnect these patches of forest. and the idea is to reintroduce the tamarins there in the near future.

“Eighty percent of the black lion tamarin population is at Morro do Diabo and the other 20% are scattered among smaller fragments,” said Gabriela Cabral Rezende, coordinator of the black lion tamarin conservation program at IPÊ.

Endemic to a small geographic region, the tamarin has gone extinct in some areas where it once lived, like the Tietê River Basin. “The only viable population today [able to maintain itself on its own] is at Morro [do Diabo], and is estimated to have 1,200 individuals,” Rezende said. “If we start from there and think strategically how we can in fact improve the species’ conservation, we intend to now focus on the population in the Upper and Mid-Paranapanema River Basin. We could create a second viable population there, where today there are small, isolated groups.”

The populations in the region, isolated in small forest fragments, are being connected by ecological corridors, a policy IPÊ has been promoting since the 1990s.

“I knew a guy who owned a farm next to Morro do Diabo and he had patches of forests with black lion tamarins. I asked him not to do anything on his farm, and he promised me he wouldn’t,” Valladares-Padua said. “One day, his brothers called me saying they had cut down the patch of forest that night and that there was one tree with five tamarins in it, and that we had to go there and save them. I went, and the animals ended up going to São Paulo Zoo … but I learned a lesson: you can study lion tamarins all you want, but if you can’t resolve the habitat issues, the issues with the people that are there, the ones who own the land … that’s where the IPÊ conservation model comes in.”

IPÊ estimates there are 500-600 black lion tamarins spread out between 19 fragments in the region. “They are small groups,” Rezende said. “Some have 20 tamarins, some five, some 40 … it’s precisely these smaller populations that we are focusing on, working to save them either through management or with the corridors.”

Management options include strategies ranging from connecting populations to transporting animals from one fragment to another to help the species gain the genetic diversity that their geographic isolation didn’t allow.

Golden-headed lion tamarin: Between cocoa plantations and fragmentation

The golden-headed lion tamarin (Leontopithecus chrysomelas), also known as the Bahian tamarin, is the member of the genus that has managed the best to adapt to the presence of humans in its midst. This surprised researchers, who for many years thought the Bahian tamarin needed mature, well-preserved forests for survival. When it was shown that the golden-headed tamarin lived relatively well in areas where humans circulate, the way they were studied and conserved changed.

“We can say that, in general, the species lives well in mature forest — of course, it’s the original environment — but also in forests with human presence,” said Leonardo Carvalho de Oliveira, scientific director of the Bicho do Mato Research Institute and Brazilian coordinator of the Bahian Lion Tamarin Conservation Initiative (ICMLB). “They also reproduce very well in the cabrucas” — areas where cocoa trees are planted in the shade of native trees in the forest — “have high population densities in diverse types of  vegetation, and they use a broad variety of trees.”

The Bahian tamarin’s adaptability put it, for a time, in a more comfortable situation than its cousins. But the species still has to deal with fragmented forest and loss of habitat. In 2020 researchers thought the species’ condition was solid enough to call for scaling down its conservation status from the current level of endangered to vulnerable. But new data show that the scenario is more worrisome than previously believed.

Oliveira is a professor at Rio de Janeiro State University (UERJ) and Santa Cruz State University (UESC). One of his doctoral candidates, Joanison Vicente dos Santos Teixeira, is recalculating the population estimates for the golden-headed lion tamarin as part of his Ph.D., using the same methodology as in 1994 and 2007 studies. If in the past decade it was thought there were between 15,000 and 20,000 of the animals in the wild, the preliminary data seem to indicate that numbers have fallen and that a change in status is no longer recommendable.

In some places where the Bahian tamarin lives, even the forest no longer exists. In other places, the trees may still be standing, but the tamarins are gone. It’s not known whether disease or hunger caused these groups to disappear.

“When the forest fragment is very small, we get what is called a border effect. The trees on the periphery are exposed to weather, wind and sun and end up dying,” Oliveira said. “The resources that were there disappear, and plants stop bearing fruit. And if there is no fruit, there is no food and then there are no animals.”

One alarming result that the researchers found was that the golden-headed lion tamarin has become extinct in a number of locations in southwestern Bahia and northeastern Minas Gerais state. Despite being called the “Bahian” tamarin, the species was also a Minas native. But today, it’s considered extinct in that state.

Researchers estimate that the minimum living space needed for an individual golden-headed lion tamarin would be 40 hectares (100 acres) of uninterrupted forest. This is the minimum, but isn’t enough to sustain a group of tamarins for the long term. The smaller the forested area, the more susceptible they are to lacking food resources, and the less likely they become to reproduce and perpetuate the species.

“There is loss and fragmentation,” Oliveira said. “Forests are being removed and fragments are farther apart from one another. When you remove forest, whether for a roadway, linear development, a series of human projects, you isolate populations in very small environments that oftentimes don’t have enough resources.”

For a long time, the conservation strategy for the Bahian tamarin was also fragmented, with studies carried out only occasionally in the region. But eventually, the idea of protecting the animals began to take hold among the local people. In 2019, after it was found that habitat had been lost and that cocoa crops — a tamarin-friendly environment because of the cabrucas agroforestry system — were being substituted by other crops, experts held a workshop to kick off the golden-headed lion tamarin protection initiative, led by biologist Kristel de Vleeschouwer.

“We began to discuss the need to start something up,” Oliveira said. “We already have the Golden Lion Tamarin Association [which protects the golden lion tamarin], we already have IPÊ [which protects the black lion tamarin], and also the SPVS [which protects the black-faced lion tamarin]. Just because the golden-headed lion tamarin is the most secure of the bunch doesn’t mean we should let things get bad before we start to do something.”

And so the Bahian Lion Tamarin Conservation Initiative, or ICMLB, was born. It involves six strategic principles, three of them core and three supporting. “We created this initiative with the goal to maintain and have sustainable and connected Bahian lion tamarin populations living within and between the conservation units,” Oliveira said. “These projects will be supported by the network of those involved either directly or indirectly with the lion tamarin. This means the local population’s involvement is essential. There are many conservation units in the region, but the rest is all private rural property.”

One of the objectives is to speed up the registry of land in the region, both for the conservation units as well as for rural properties and settlements. “Endorsement of legal reserves, environmentally protected areas [like hilltops and riverbanks, which are protected under the Forestry Code] is essential,” Oliveira said. “It does no good to say that a species is living inside a conservation unit if it doesn’t really exist. Making the units effective requires having them officially registered. We have a strategy which I’m really hopeful about because it is focused on using cabrucas. It is a strategy that places value on the land, the territory, and the specific tradition of cocoa farming. In fact, the objective is to maintain the functional connectivity of the cabrucas, keeping them as they are in the forest. There is much value in them to be maintained: economic value, ecological value, and mostly cultural value. It’s about bringing back the pride of those who are cabruqueiros, the cocoa farmers.”

Other strategies involve political, financial and communication resources. The objective is to make projects transparent and, most importantly, bring the locals on board as strong allies: “We believe that the golden-headed lion tamarin’s survival depends on the Bahian people,” Oliveira said. “It’s a state symbol, just like the golden lion tamarin is the symbol of Rio de Janeiro.”

Black-faced lion tamarin: Unknown and isolated

Unlike its cousins, the black-faced lion tamarin (Leontopithecus caissara) or “coastal tamarin” as it’s popularly known, is relatively new to science. It was described only in 1990, by researchers Vanessa Persson and Maria Lúcia Lorini. Until then, there were only rumors that a tamarin similar to the black lion tamarin had been seen in the region of Guaraqueçaba in the state of Paraná.

When this tamarin was finally described, one hypothesis was that it was a variation of Leontopithecus chrysopygus, the black lion tamarin. But later studies, one in 1999 and another in 2008, discarded the idea that it was a subspecies, and the new species was confirmed.

The black-faced lion tamarin’s area of occurrence is paradoxical. While it lives inside the largest continuous strip of Atlantic Forest that remains in Brazil — a luxury compared to the other tamarins — the black-faced tamarin is literally stranded. This happened when a canal was dug to connect the ports of Guaraqueçaba and Paranaguá on the Paraná coast to inland São Paulo.

The Varadouro Canal began being dug at the beginning of the 19th century and was finished in 1953, separating a sliver of land, known as Superagui, from the South American continent. The water barrier is impassable for small primates, dividing the tamarin population in Superagui from the rest of the species that remained on the mainland, where they’re found in the municipality of Cananéia in São Paulo state and Guaraqueçaba in Paraná state.

As it was the most recently described of its genus, much is still unknown about the black-faced lion tamarin. It’s not understood why its population remains small, given the fact that it has such a large area of forest to occupy. But the most important question facing researchers: how many black-faced lion tamarins exist in the wild?

Understanding the population’s size is one of researcher Elenise Sipinski’s priorities. She’s responsible for the black-faced lion tamarin conservation project run by the Society for Wildlife Research and Environmental Education (SPVS) since 2018.

The last population count was carried out in 2002 by researcher Alexandre Túlio Amaral Nascimento and his colleagues. They estimated at the time that 392 individuals were living in the wild.

“What we want to know today is where these groups are, how they are related, and whether or not the population is at least sustaining itself. If by chance we need to carry out a project ex situ [captive management], we will at least already have the animals mapped out in the region,” Sipinski said.

The challenges abound. The first is that the groups of coastal tamarins have an area of up to 300 hectares (740 acres) available to them, making them difficult to locate and monitor. The second is that restrictions imposed in response to the COVID-19 pandemic reduced fieldwork and delayed studies. For now, eight groups of these tamarins have been identified, some of them monitored by camera traps set up in Ariri and Superagui. The goal for the end of 2022 is to trap at least one group of the coastal tamarins to collect biological samples (to find out, among other things, if the species had contact with yellow fever) and to place tracking collars on them.

No safety population

Even though their population density is thought to be low, the black-faced lion tamarins enjoy the most comfortable situation in terms of habitat compared to their cousins, despite the separation between the island and mainland populations. They live in a still-preserved area, thanks more to its location rather than to any conservation actions, and have room to grow. Their main threat today would be extreme weather events affecting their habitat, such as strong wind or extratropical storms. In 2018, a hurricane devastated 2,000 hectares (4,900 acres) of forest where some groups of tamarins lived. Another threat is disease, such as yellow fever.

“Howler monkeys died in the area [where the coastal tamarins live] but we didn’t find any dead black-faced lion tamarins,” Sipinski said. “We will have to do some research to find out if the tamarins came into contact with the disease.”

The primatologists’ main concern with extreme events in the black-faced lion tamarin’s area of occurrence is the lack of a captive population of the species. Of the four species of lion tamarins, the coastal one is the only one not present in zoos or primate centers, and has no safety or reserve population, as the researchers call them. An outbreak of a single disease like yellow fever could wipe the species off the planet without any chance of recovery.

“They are wild animals and whatever happens in the wild will be definitive for them,” Sipinski said. “Today, we have no way to carry out any sort of release, transport or reinforcement programs. For example, something like what was done with the golden lion tamarin — a benchmark case of long-term transportation — would currently be impossible with the black-faced lion tamarin.”

The decision to have a population in captivity was only made in August 2021, during a workshop on an action plan for the species. There’s still much planning ahead. A group of individuals big enough to put the survival of the wild groups in check cannot be taken from nature. How many to remove, where to move them, at what ages and at what time of year are questions the researchers will only be able to answer when they have more data. For now, the population count continues to be the top priority as it will yield the information that will guide all the subsequent management decisions.

“What’s important is to have funding to plan it [the removal of animals from the wild],” Sipinski said. “Whether you will do it, the best way to do it, so it will have the least impact on nature possible.”

Working together to protect the primates

The task of evaluating, reevaluating and monitoring all four lion tamarin species is part of the national action plan (NAP) for conservation, an initiative of the Chico Mendes Institute for Biodiversity Conservation (ICMBio) through the National Center for Brazilian Primate Research and Conservation (CPB). Reevaluating each species and monitoring its area of occurrence is one of the plan’s priorities.

“One of the NAP’s main goals is to guarantee the land to maintain the smallest viable population in the wild to guarantee that a species will survive for at least the next 50 or 100 years,” said Mônica Montenegro, an environmental analyst at ICMBio and coordinator of the  National Action Plan for the Conservation of Atlantic Forest Primates and the Maned Sloth. The NAP covers 14 primate species — the four lion tamarins included — in addition to sloths.

Montenegro said the greatest challenge in the Atlantic Forest continues to be protecting the few remaining rainforest fragments, given the spread of urban spaces in the region. “This is where our largest cities lie, where 70% of the population lives, where Brazil’s largest [industrial] centers are,” she said. “Most of the threatened primate species are native to the Atlantic Forest and the challenge for the species that are left in the biome is to have to live near to people, to urban spaces. And the destruction continues. Every year there is deforestation; even if it is going on at a slower rate than in other biomes, it’s worse because the Atlantic Forest has already been devastated in the past.”

Montenegro said primate conservation depends on protecting and connecting their habitat. “The first objective of most plans of action is always the habitat, which is the greatest threat to primates because they are forest creatures. They need standing forest and ways to pass from one patch of forest to the other, since we no longer have large stretches of continuous forest,” she said. “They need to move from one stand of trees to the other, to trade individuals, to trade genetic material and we have to provide — since we’re the ones that took it away — that connectivity.”

*Published in english by Mongabay. Translated by Maya Johnson