Geographic Distribution and Habitat
Emperor tamarins (Saguinus imperator), who go by the nickname “mustache monkeys,” are native to South America. They reside just south of the equator within the southwestern Amazon River Basin in eastern Peru, northern Bolivia, and the northwestern Brazilian states of Acre and Amazonas. Populations are geographically distributed east of the upper Purus River; between the Purus River and Rio Acre; east of the upper Juruá River to the Tarauacá River and Juruparí River; west to the Urubamba River and Inuya River; and south of Tahuamanú River.
Lowland and lower montane tropical rainforests, seasonally flooded forests, secondary forests, and remnant forests (also known as “fringe patches”) provide the species’ habitat. Typically, the monkeys are found deep in the rainforest within the middle and lower layers, but they can sometimes be found in open tree-covered areas.
Sharing the Amazon River Basin’s tropical and moist habitat are two subspecies to the emperor tamarin: the black-chinned emperor tamarin (Saguinus imperator imperator) and the bearded emperor tamarin (Saguinus imperator subgrisescens). Black-chinned emperor tamarins (the nominate subspecies) are found across the rainforests of Brazil, Peru, and Bolivia; bearded emperor tamarins are mostly found in the rainforests of Brazil and Peru.
Both subspecies prefer lowland tropical rainforests, taking up residence in the tree canopies of river basins. But like the emperor tamarin (their “parent” species), these monkeys reside in other habitats as well. Seasonally flooded forests, broadleaf forests, the edge of remnant forests, rainforests that grow on flatlands, and evergreen forests provide alternative addresses.
Neither the parent species nor its “children” are usually found high in the trees. Rather, emperor tamarins most often dwell between 80 and 90 ft (24–27 m) from the forest floor.
Size, Weight, and Lifespan
This New World monkey is about the size of an eastern gray squirrel, with a long torso and long limbs proportionate to its tiny size. Head-to-body length is 9–10 in (23–25 cm), but its tail adds another 14.8–16.3 in (35–41.5 cm). Emperor tamarins weigh a mere 10.6–18 oz (0.3–0.5 kg). They are sometimes referred to as “dwarf monkeys.”
Like other members of the Callitrichidae family of primates, sexual dimorphism is unremarkable in this species.
Lifespan for emperor tamarins in the wild is between 10 and 20 years.
In zoological nomenclature, when a species is split into subspecies, the originally described population is retained as the “nominotypical subspecies,” which repeats the same name as the species.
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It’s not surprising that this diminutive primate with the long, silky white whiskers that sweep outward from its muzzle like an out-of-control mustache, nearly overwhelming its tiny body, has been given the nickname “mustache monkey.” Long white hairs also extend from the chin. Younger emperors, those who are not yet fully mature, have shorter mustaches.
(Just don’t confuse the little emperor with another mustachioed monkey, Spyx’s moustached tamarin (Saguinus mystax), a native of Brazil and Peru, whom Mother Nature has given a more modest mustache.)
Additional physical characteristics that further distinguish tamarins from other New World monkeys are far less obvious. While some taxa within the family Callitrichidae have prehensile tails, tamarins do not. Tamarins, like their smaller marmoset cousins, are fitted with modified claws, rather than nails, on each of their digits except for the big toe, which has a nail. Their claws are believed to be an adaptation to their environment, rather than a vestigial trait of their early evolutionary ancestors. And if you could peek inside their mouth, you’d see that they are equipped with only two, rather than three, molar teeth on either side of each jaw.
A pale pink or white muzzle lends contrast to an otherwise dark-colored face. Deep brown eyes sit beneath a pronounced brow line. Decorating the crown of the head is a black fur cap, and on either side of the head, scalloped ears sit demurely and listen to the sounds of the rainforest.
The emperor tamarin’s delicate frame is cloaked in a silky gray coat, dabbled with flecks of yellow. Its lower rump and long, nonprehensile tail are rust-colored. Palms and feet are black.
As omnivores, emperor tamarins eat foods of both plant and animal origin. The Amazon River Basin’s year-round tropical, moist environment provides an abundance of vegetation for emperor tamarins to dine upon. Fruits, flowers, nectar, and a plethora of woody plant species, especially found in secondary forests, provide the monkeys’ plant-based banquet. Plant exudates (saps, gums, and latex) are also enjoyed, but tamarins must patiently wait for another animal, like their marmoset cousin, to gouge these sticky substances from a tree’s bark. (Marmosets easily perform this task thanks to their specialized dentition, a morphological adaption lacking in tamarins.) No matter. Emperor tamarins are patient opportunists. Insects, spiders, snails, bird eggs, tree frogs, lizards, and small rodents satisfy their carnivore cravings.
Behavior and Lifestyle
These miniature monkeys are active during daylight hours and spend most of their time in the trees, making them diurnal and arboreal, respectively. Emperor tamarins are incredibly agile, hopping or running quadrupedally (on all four limbs) from tree branch to tree branch as they travel, gracefully and with alacrity, through the forest. Their ability to move quickly through their treed environment helps them to elude predators. Sometimes they carry their tail partially upright, with the tip drooping downward. Slender branches support their light body weight, permitting them to reach for food that is inaccessible to heavier animals. Clutching a branch with a clawed grip, they extend their free arm and retrieve a piece of fruit with their other hand.
About two-thirds of female emperor tamarins possess trichromatic vision, meaning that they are able to recognize three distinct colors. This selective adaptation assists them in finding ripe fruit, which is a dietary staple for the species. All other individuals possess dichromatic vision, meaning that they are able to recognize two distinct colors. Whether trichromatic or dichromatic, all individuals are able to spot prey and detect camouflaged predators thanks to their keen eyesight.
Their long tail, while incapable of gripping, helps them to balance as they travel through the forest. When clinging vertically to tree trunks, the monkeys make good use of their claws by digging them into a tree’s bark.
At night, emperor tamarin families sleep cuddled together inside the hollow of trees that stand up to 85–90 ft (26–27.5 m) tall.
The late Swiss-Brazilian naturalist-zoologist Émil August Goeldi, who has several species—including Goeldi’s marmoset—named after himself, is reported to have jokingly given the name “emperor” to this little primate for its resemblance to Emperor Wilhelm II of Germany—thanks to that glorious mustache. (Fun fact within a fun fact: Goeldi, himself, sported a similar mustache!) Whereas Wilhelm’s mustache was long and upturned (no doubt thanks to deliberate grooming) the emperor tamarin’s mustache droops downward in its natural position. So, to make these tiny monkeys more resemble their royal human namesake, taxidermists are known to twist the mustaches upwards of emperor tamarin specimens. Some might find this tweaking kinda’ creepy or perverse—but hey, taxidermy . . .
Emperor tamarins can travel at speeds of up to 24 miles per hour.
Both tamarins and marmosets are considered to be the most primitive monkeys because of their anatomical and reproductive characteristics.
Emperor tamarins are social creatures who live in family groups (or “troops”) of 2 to 20 individuals, with average troop size closer to 8. A troop comprises both males and females, typically with a predominantly male membership. But it’s the eldest female who acts as a troop’s leader, reigning over mature males.
Members enjoy a close, cooperative relationship with one another. Together they forage, eat, play, engage in mutual grooming sessions, sleep overnight, and protect the boundaries of their territory from intruders.
Upon reaching sexual maturity, both sons and daughters may leave their natal group and either join another existing group of emperor tamarins or start a new group with other individuals who’ve left home.
The monkeys forage over a home range that covers about 0.12 sq mi (30 ha), with the dominant female and her mate leading these expeditions. But the emperors are not alone. Politely sharing their range are even-tinier Weddell’s saddleback tamarins (Leontocebus weddelli) and, tinier still, Goeldi’s marmosets (Callimico Goeldii).
Emperor tamarins commonly form mixed-species groups with the saddleback tamarins, and to a lesser (known) degree, with Goeldi’s marmosets. These affiliations benefit each species: by offering greater safety in numbers against jungle predators (who include wild cats, snakes, and birds of prey); and by offering more opportunities for successful foraging expeditions.
Both saddleback tamarins and Goeldi’s marmosets travel in the forest understory, about 33 ft (10 m) from the ground. Emperor tamarins spend more time in the lower or middle canopy, above 33 ft (10 m). Being more lithesome, the smaller-bodied monkeys typically arrive at a food source ahead of the emperor tamarins.
Agonistic or altruistic? Emperor tamarins have been known to use their “might” to intimidate the smaller monkeys into giving up their premier position on a fruit tree. But emperors have also been known to share, dropping pieces of fruit to the lower levels of the forest canopy to their “downstairs” neighbors.
Overnight, the three species separate and rejoin their respective troops.
Other animals (sympatric species) who make their home in the southwestern Amazon River Basin include tapirs (Tapirus terrestris); jaguars (Panthera onca); capybaras (Hydrochoeris hydrochaeris), who are the world’s largest living rodents; kinkajous (Potos flavus); and white-lipped peccaries (Tayassu pecari).
Vocalizations are key to tamarin communication. Emperor tamarins use vocalizations to send messages to fellow troop members, to other-primate-species affiliations, and to intruders.
Mornings begin with a lengthy “wake up” call from their sleeping sites as the monkeys rally one another to get going and start foraging. While foraging deep in the forest, the tamarins emit loud, sustained contact calls that carry more than 492 ft (150 m) and help establish one another’s location. To warn intruders to keep away from their territory, they emit high-pitched, shrill calls. Chirps and hisses are included in their everyday dialogue.
Tamarins are able to distinguish calls of their fellow troop members from those of affiliative species. As an example, compared to saddleback tamarin vocalizations, emperor tamarin calls are broader in frequency with shorter, rapidly emitted notes. Emperor tamarins are adept at discerning these different tamarin “dialects” and will respond to one another’s alarm calls.
As with virtually all primates (human and nonhuman!), body language conveys certain messages or gives clues to one’s mood. Emperor tamarins are known to rapidly flick their tongue when agitated. Tongue-flicking often accompanies the intimidation calls they emit to warn off predators. But a nursing mother may also extend and curl her tongue to solicit the help of a male nursemaid. Emperors may also frown; however, their range of facial expressions is more limited as compared to higher primates.
Olfactory messaging is used by these monkeys as they travel through the forest each day. Equipped with olfactory glands on their chest and genitals, emperors establish territorial boundaries by leaving scent excretions on tree branches.
Mutual grooming sessions are more than making one another look good or taking tangles out of fur coats. This tactile activity helps to establish crucial social bonds with fellow troop members.
In emperor tamarin societies, the dominant female mates with multiple males. (This practice is known as a polyandrous mating system, as opposed to polygynous where an alpha male mates with multiple females.)
Wildlife biologists posit that a polyandrous mating system is a survival mechanism, a strategy of the dominant female to ensure paternal support for her offspring. Because males cannot be sure whether or not they have sired an infant, they behave under the assumption that surely, they are the biological dad to at least one. By helping the female with child care, the males gamble that they are ensuring the future of their progeny and viability of their gene pool.
Emperor tamarins are seasonal breeders. After a gestation period of about 4.5 months (140–150 days), a female gives birth. Twins are the norm, but single births and, occasionally, triplets occur. Births happen during the moist or rainy season, between September and March, when foods are most abundant. Interbirth interval in the species is six months.
A mother nurses her infant every 2 to 3 hours, for about 30 minutes each session. All the adult males (the biological dad and those “I might be the dad” males) spring into action to help the mother. Males take turns carrying the infants on their backs, to and from the mother for weaning sessions. Their assistance allows the mother to rest, or she might go off and forage. Males protect the infants and offer comfort and reassurance when the little ones cry.
But young emperor tamarins are active and require a lot of supervision. As they reach the “toddler stage” and begin to explore their environment, they inadvertently put themselves at great risk of falling to their death. Mortality in the wild is reported at its highest between the first 5 and 15 weeks of life. To help ensure that the youngsters remain safe, a dominant female’s eldest daughters (those who have remained in the natal group) assist with child care.
At about three months of age, emperor tamarins are considered weaned. By age 2, they are considered fully mature.
Like other fruit-eating (or partially frugivorous) monkeys, emperor tamarins help to replenish their forest habitat by dispersing, via their feces, the seeds of the fruits that they eat.
They are valued citizens of the Amazon rainforest and the ecosystem in which they live—which includes the food chain. Emperors’ small bodies are a meal for larger predators such as snakes, raptors, wild jungle cats, and dogs.
Because of its widespread distribution and no imminent threats to the overall population, the emperor tamarin is classified as Least Concern by the International Union for Conservation of Nature (IUCN, 2015), appearing on the IUCN Red List of Threatened Species. Among the subspecies, black chinned emperor tamarins are classified as Data Deficient (IUCN, 2008), while bearded emperor tamarins are classified as Least Concern (IUCN, 2008).
But as has been seen in many other species, over and over, a trajectory toward more grave classifications and precarious survival does not take long. And human primates are usually the cause.
Natural emperor tamarin habitat is rapidly disappearing as humans clear the land for agricultural use, housing, infrastructure (such as highways and utilities), and logging. As habitat is increasingly lost, so are more and more emperor tamarin individuals, placing the overall population in steady decline.
Though emperor tamarins are not hunted for their flesh (known as “bushmeat”)—likely because of their tiny size—the small monkeys are hunted, kidnapped, and sold as pets—victims of the illegal wildlife trade.
The emperor tamarin is listed in Appendix II of the Convention on International Trade in Endangered Species (CITES), an international agreement between governments whose goal is to ensure that international trade in specimens of wild animals and plants does not threaten their survival.
Although no conservation programs exist with specifically the emperor tamarin in mind, those monkeys who live in protected areas enjoy a measure of safety. These areas include Manú Nationwide Park in Peru and Manuripi-Heath Amazonian Wildlife National Reserve in Bolivia. Both subspecies, black-chinned emperor tamarins and bearded emperor tamarins, also reside in these protected areas. While several conservation areas are found in Brazil, none are specifically dedicated to the protection of wildlife. It is likely, wildlife biologists believe, that emperor tamarins reside within these habitats, which include Rio Acre Ecological Station, Chico Mendes Extractive Reserve, Macauá National Forest, and Macauá and Antimari State Forests.
One way to help bring awareness to the species and help in its conservation may be through ecotourism. Manú Nationwide Park hosts programs and tours that give people the opportunity to see emperor tamarins, along with other species, in the monkeys’ native habitat. But ecotourism must be tempered with maintaining a pristine natural environment. Infrastructure built to allow access to the park, along with the loads of visitors, could have an adverse effect on the emperor tamarin population.
Conservationists advocate for educational programs, geared toward local peoples, that help establish an affinity between human and nonhuman primates. By directly involving local people in helping with emperor tamarin preservation, they learn to understand and appreciate the monkeys as fellow rainforest citizens. Ideally, instilled in the local human populace is a sense of national pride for this nonhuman primate who shares their world, so locals become committed to protecting the species.
Of course, captive emperor tamarins are found in zoos around the world. (One source puts the number at 500 individuals, total.) Apenheul, in the Netherlands, describes itself as a “green zoo.” Here, emperor tamarins are one of 35 species of primates—and over 300 primates overall—who freely roam the park. Apenheul (the name is taken from the word “apen,” meaning “apes” or “monkeys” and from the archaic Dutch word “heul,” meaning “refuge” or “safe place”) participates in a European breeding program for emperor tamarins. The Apenheul Primate Conservation Trust (APCT), created in 1994, supports nature conservation projects for the protection of wild primates and their habitats.
Written by Kathleen Downey, July 2021