Geographic Distribution and Habitat
The pied tamarin (Sanguinus bicolor), also known as the Brazilian bare-faced tamarin or pied bare-faced tamarin, has one of the smallest ranges of any primate in the world, located in and around the Amazonian port city of Manaus. Pied tamarins thrive best in the continuous old-growth forest that once flourished here. But many are currently forced to make do with the small patches of heavily degraded and severely fragmented forest left within a bustling city that won’t stop expanding.
North of Manaus, where forests may remain somewhat untouched (for now), a few pied tamarin groups have been observed living in lowland forests and in forests at the edges of swamps.
Size, Weight, and Lifespan
Pied tamarins are approximately 11–12 inches (28–32 cm) in length, male or female, and usually weigh around 1 pound (500 g). Their tail is much longer than their body, stretching 15–17 inches (38–42 cm) behind them.
While this species can live up to 19 years in captivity, their lives are likely around half of that in the wild.
Pied tamarins are not sexually dimorphic, meaning that males and females look essentially the same. They have cat-like furry bodies with bare bat-like faces. Their heads—all the way to the pointed tips of their ruffled ears—are completely hairless and black.
Their dark faces stand out against the white hair covering their chests, forearms, and backs of their necks. This white section suddenly ends at their midsection, and the fur covering their backs can vary from a dark brown to a light brown with a warmer, almost golden hue. The brown continues along the tops of their long non-prehensile tails, while the undersides are black.
Pied tamarins have claws, not hands, that are well-adapted for latching onto branches and bark as they scurry about the forest. They also make harvesting the gums and saps they extract from trees a much simpler process.
In addition to fruits and flowers, pied tamarins also eat sugary tree exudates like gums and saps. These they easily procure by digging into trees with their sharp and nimble claws. Some of the gums they eat come from the seedpods of the tree as well.
During the dry season, when these niches become more scarce, pied tamarins take up hunting small animals like insects, frogs, and lizards. They may also eat eggs and young birds.
Research has shown that pied tamarins are less reliant on gums and saps than other marmoset species. This difference is even evident in pied tamarins’ physiology. While other species have specially adapted teeth in their lower jaws that help them get at tree exudates by biting, pied tamarins do not. Instead, they have large canine teeth, which are better for ripping into the flesh of fruit and the small animals they hunt.
What Does It Mean?
Beneath the emergent layer, the canopy layer is the primary layer of the forest and forms a roof over the two remaining layers (the understory and forest floor). Many animals live in this maze of leaves and branches, where food is abundant.
Active during daylight hours.
A recurring period of sexual receptivity and fertility in many female mammals.
A substance, such as gum, sap, or resin, which flows from the vascular system of a plant.
The transfer of genes from one population into another through breeding.
When a species’ population is reduced in size (i.e. by a cataclysmic event, habitat fragmentation, etc.) limiting the genetic diversity of the species.
The time of pregnancy from conception until birth.
The process by which a large, continuous stretch of habitat gets divided into smaller, disjointed patches of habitat.
The breeding of closely related individuals, especially over many generations.
The group into which an animal is born.
Nonprehensile or Non-prehensile:
Incapable of grasping or gripping (opposite of prehensile: capable of grasping).
A chemical that an animal produces that changes the behavior of another animal of the same species.
A pattern of mating in which a female animal has more than one male mate.
A forest that has regrown after a major disturbance, such as fire or timber harvest, but has not yet reached the mature state of primary forest.
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Behavior and Lifestyle
Pied tamarins are diurnal, spending their days clambering and leaping about the trees foraging for food and socializing. Being so small and equipped with long tails that help them balance, they easily scurry on all fours along thin branches. Powerful hind legs make them excellent—not to mention daring—leapers as well. Though no level of the forest is altogether off-limits, they rarely visit the ground and prefer feeding higher in the canopy where they have ready access to everything they might want to eat. With their sharp claws, they easily process fruits or dig through bark to get at the tasty saps and gums underneath. When hunting insects and other small creatures, they are able to move quickly and quietly—pouncing before their prey has any sense that they were in danger.
Tamarins are generally territorial and do not take kindly to other groups of monkeys entering their space. Compared to other species, however, pied tamarins are less adaptable and more vulnerable to stress.
In 2005, in an effort to promote empathy for the species, the pied tamarin was elected as the official mascot of Manaus.
The pied tamarin has the smallest natural range of any primate in the entire world.
Pied tamarins are highly susceptible to stress and much less adaptable to changes in their environment than other tamarins.
Daily Life and Group Dynamics
Pied tamarin groups have rather atypical structures compared to other primates and even other tamarin species. They are often composed of multiple males and multiple females, ranging in size from two to fifteen members. Each group has a dominant female who is the only female allowed to mate. She releases a pheromone that suppresses the other females’ estrus cycles, ensuring this be the case.
Pied tamarins have been found to live in a variety of social arrangements with the most common being a single dominant female living amongst several males. But sometimes groups are more mixed, and may even have more males then females. Though it is very rare, researchers have observed groups of pied tamarins living as one male in the company of multiple females. Another rare set-up, but one that does occur, is a male and female pair living without any other pied tamarins. Perhaps only while in between groups, individual pied tamarins are sometimes observed all by themselves. So far, researchers are not certain why pied tamarin groups show such fascinating variation in their social arrangements.
Typically, no matter how a group is composed, its members experience very little conflict between them. A group takes caution to avoid other groups of pied tamarins as well as other tamarin species, in particular red-handed tamarins. These two species are increasingly finding themselves at odds with each other as their habitats shrink and they are pushed closer and closer together, causing competition and conflict.
Tamarins are well-known for being avid communicators, using a wide array of vocalizations, body postures, hand gestures, and olfactory signals to convey information to others.
Pied tamarins are no different. Chirps, trills, cries, long calls, and whistles play vital roles in pied tamarin society. The contexts in which each may be used, as well as the variation with which they are emitted, are key to understanding their meaning. A long call, for instance, might be used to tell other tamarins in the area of a group’s location, warning them to keep a wide berth—or it may be used by another member who has ventured too far from the group, thereby initiating them to search for the lost individual. The same call may be made more quietly while the group migrates through the forest, helping the group to keep track of everyone as they navigate the thick jungle foliage.
When pied tamarins are not on the go, stopping to rest or to forage, they switch to what are called “tsê” signals. These vocalizations are so quiet that researchers only knew they were being made when they noticed them on their spectrograms during their data analysis, after their field study. Multiple variations of tsê signals were recorded, but their meanings and purposes are not entirely clear at this time. Cotton-top tamarins at New York City’s Central Park Zoo have been observed to make similar calls in the presence of staff members they think might be a threat. Could it be that the pied tamarins were responding similarly to the researchers’ presence in the wild?
A number of chirps, cries, and trills are used to alarm the group if a predator is approaching or when a rival tamarin group comes too close for comfort. With such variation, it is possible that pied tamarins’ alarm calls refer to specific predators so that group members know how best to respond to the incoming threat. More research is needed before we can be certain.
Pied tamarins have also been observed to emit what researchers call “Ploc” signals. Named phonetically after how the calls sound, adults occasionally emit a “ploc” signal when they complete a leap from one tree branch to another. Infants sometimes make the same sound when they successfully capture live prey. At this time, the ploc signal’s meaning is not clear, however.
As the city of Manus expands and pied tamarins’ habitats shrink, conflicts have arisen between them and red-handed tamarins, as the two species compete more and more for the same resources. However, red-handed tamarins have learned to mimic the pied tamarins’ long calls—a feat that many researches compare to humans speaking another dialect or accent. By making the long calls with a pied tamarin accent, red-handed tamarins appear to be successfully preventing conflict with their potential rivals. Researchers have not yet deduced why this practice works, but the fact that pied tamarins have not learned to make their own calls in a red-handed tamarin dialect suggests that this species may have less vocal flexibility as compared to other tamarins. Curiously, another creature that has learned to mimic pied tamarin calls is one of their natural predators. Margay cats use this uncanny ability to attract unsuspecting pied tamarins away from the protection of their group, where they become easier prey. How or if pied tamarins are able to distinguish between genuine and sham calls is another area awaiting more research.
Facial expressions are another effective form of communication for pied tamarins, and one to which their naked faces likely lend complexity and nuance. Unfortunately, the facial repertoire of pied tamarins has not seen extensive research yet. Tongue flicking, in which an individual moves their tongue quickly in and out of their mouth, is an odd-looking but meaningful gesture for many tamarin species, including pied tamarins. Like their vocalizations, context and variation determine the signal’s meaning, which can be anything for simple acknowledgement of another’s presence to expressing one’s anger. Other times, it may be used to show innocent curiosity.
Scent is an effective way for many primate species to mark their territory. Pied tamarins are equipped with special scent glands above their genitals and near their bellies that they use to leave olfactory signals, warning other monkeys to keep away. Other tamarin species are known for using their scent-marks in exceptional ways. Golden lion tamarins, for instance, use their own to mark where the best food can be found. At this time, however, any of the pied tamarin’s more exceptional uses of olfactory communication have not been described.
Reproduction and Family
Many tamarin species are polyandrous, meaning that females mate with multiple males. More specifically, what researchers often observe in this genus they call “cooperative polyandry,” where the female and all of her mates provide care for her offspring. Polyandry, which is rarely found in nature, is believed to be beneficial in the case of tamarins due to the energy needs of birthing and caring for the offspring. Being so small—and given that tamarins almost always bear twins—females need all the help they can get to raise their young. None of her mates can know if they are the true father, so they are all too happy to help out as if they are.
Pied tamarins add another twist to cooperative polyandry, which is that only one female mates per group. A special pheromone she releases actually suppresses estrus in all her other female group members. Her own estrus can occur at any time of the year and, on average, lasts fifteen days. Once she has mated, her twins take around 185–195 days to gestate and are born with all their fur, including some extra white fur covering their heads that they’ll eventually lose.
For the first few weeks, the twins are completely helpless. Luckily, everyone in the group pitches in to care for them, giving the mother a chance to recuperate from the ordeal of pregnancy. For the time being, her only responsibility is nursing. By twenty-one days old, her twins are already capable of exploring their world, but they still prefer to be carried as the group treks through the jungle. Usually the males take full responsibility for carrying the young. At around four weeks of age, the twins are weaned by the mother. Now the group helps with feeding too. At twenty weeks, the twins can feed themselves, and they begin to take more responsibility for themselves.
Female pied tamarins are mature at around eighteen months of age. Males take a little longer, generally about two full years. Both sexes may then disperse from their natal group to join or form their own.
As fruit-eating primates, pied tamarins likely play an important role in seed dispersal. Moving around the forest, they sow undigested seeds through their feces. Tamarins are small monkeys who sometimes partake in the nectar of flowers, which makes them possible pollinators as well.
Pied tamarins are prey for wild cats, including the margay cat, as well as for snakes and birds of prey.
Conservation Status and Threats
The pied tamarin is classified as Critically Endangered by the International Union for Conservation of Nature (IUCN, 2015), appearing on the IUCN Red List of Threatened Species—an increased threat level from its previous 2008 evaluation as Endangered. Unfortunately, due to its rapid population loss in the last decade, this species was added to Primates in Peril’s 2018–2020 List of the 25 Most Endangered Primates.
Pied tamarins face a daunting wave of threats, all of which are compounded and worsened by their extremely small range near the rapidly expanding port city of Manaus. As the city grows to accommodate new settlements, their natural habitat wanes. Agriculture, livestock production and the energy and infrastructural needs of these and other urban development projects are daily destroying more of the already scant forests pied tamarins would otherwise call home. What is not destroyed is degraded to the point of being useless to them—this species being particularly vulnerable to changes in its environment.
With their habitat dwindling, pied tamarins find themselves in competition with other species, particularly red-handed tamarins who share part of their range. Back when there was adequate forest coverage, these two species would have had no problems giving one another a wide berth. But as human activities push them into smaller and smaller areas where they have less and less access to resources, conflict with red-handed tamarins becomes unavoidable. Since pied tamarins are the less adaptable of the two species, they are typically more adversely affected by this trend than their red-handed relatives.
As if none of that were enough, the fragmented habitat that remains today has already been shown by researchers to be affecting pied tamarins’ genetic diversity. As groups become isolated by the sprawling city, gene flow between different populations slows to a stop. When this happens, it leads to inbreeding. The loss of diverse genes makes new generations more susceptible to genetic defects, parasites, and disease. As offspring become less and less viable, their extinction becomes practically inevitable.
Urbanization creates another host of serious threats for pied tamarins. For instance, the dogs and cats kept by farmers and other human settlers as pets often kill pied tamarins. Newly erected power lines electrocute pied tamarins who don’t know any better than to use them as a bridge between the fragmented canopies. Infrastructure brings more cars and, with them, the potential for pied tamarins to get hit by them.
Pied tamarins are also a species routinely collected for the exotic pet trade. Taken from the wild, usually by violent means, tamarins that become pets live out the rest of their lives in misery. Deprived of any and all social interactions with their own species and often malnourished, their chances of contributing their genes to the next generations are reduced to zero.
Compounded, the threats pied tamarins are facing are considerable for such a small monkey occupying such a small portion of the earth. It is projected that their populations are likely to see an 80% reduction—or possibly more!—over three generations. That means that the pied tamarin could be extinct in the wild within the mere span of 18 years unless drastic measures are taken immediately to converse them.
The pied tamarin’s situation is perhaps one of the direst of all the world’s primates—so much so that they are the only tamarin species with its own National Action Plan.
Since 2011, the conservation of pied tamarins has been overseen by the Center for the Protection of Brazilian Primates (Centro de Protecao de Primatas Brasileiros – CPB), which is part of the Chico Mendes Institute for the Conservation of Biodiversity (Instituto Chico Mendes de Conservação da Biodiversidade – ICMBIO)—a section of the Brazilian Ministry of the Environment. These governmental organizations were responsible for formulating the National Action Plan for the Conservation of the Pied Tamarin. This document set a plethora of clearly defined goals to be accomplished over the next five years, calling for more research and surveys of pied tamarins near Manaus, the initiation of reforestation projects in and around the city, and formulating programs to educate local populations about the important of pied tamarin conservation—among many other plans.
Numerous nongovernmental and international organizations have also stepped in to help. The Durrell Wildlife Conservation Trust, for example, supports field conservation programs for pied tamarins. This organization has had earlier successes bringing another tamarin species back from the brink of extinction. In 2008, the black lion tamarin was down-listed from Critically Endangered to Endangered thanks to its efforts, which included the reforestation of over 700 ha of forest to reconnect previously isolated sub-groups of black lion tamarins and prevent genetic bottlenecks. The future of pied tamarins relies on the creation of similar ecological corridors.
As of 2009, the Brazilian government had also lent 239 institutions worldwide some 172 pied tamarins as part of a captive breeding program. Many of these are zoos that not only breed pied tamarins but also disseminate information about the plight of this species in the wild to an international audience. Many help to fund and support reforestation projects in Brazil as well. Though not ideal, captively breeding these monkeys with the intention of releasing their offspring into the region once it has been reforested may be the last hope for a species that may become extinct in the wild in the next quarter-century.
Pied tamarin groups live in several protected areas, both private and public, but only a handful are part of Brazil’s National System of Protected Areas. Furthermore, the majority of these areas are only small patches of degraded forest separated from one another by urban landscapes dangerous for pied tamarins to cross.
One of the largest and most significant technically protected area is the Adolfo Ducke Forest Reserve, which offers pied tamarins some of the last old-growth and continuous forest within their natural range. A small corridor of forest connects this reserve with 115,000 ha of forest east of Manaus, which is owned by the army. While this area is certainly significant for pied tamarins who are absolutely desperate for habitat, it is not an official conservation area and its military uses are less than ideal for such an easily stressed primate.
The Walter Egler Ecological Reserve (630 ha) and the Sauim-Castanheiras Wildlife Reserve (97 ha) are two other significant protected areas for pied tamarin conservation. But again, neither one is federally protected.
This species is listed on the Convention on International Trade in Endangered Species (CITES) Appendix I and on the Official List of Brazilian Fauna Species Threatened with Extinction as one of the ten primates in the highest risk category.
Written by Zachary Lussier, July 2021