Weighing in at barely one pound and seldom larger than 10” in length, the emperor tamarin is among the smallest of the rainforest monkeys. But what it may lack in size it more than compensates for in speed, agility, dexterity, eyesight, and raw intelligence. Possessing longer legs than other tamarins, emperors are faster and more agile in locomotion. This is one reason why they are able to maintain a dominant social position among competing tamarin species. And although they do not possess gripping, prehensile tails like some other monkeys, the long, flexible tails they have developed allow them to move with remarkable balance and agility, enabling them to jump great lateral distances between trees, and navigate high limbs that are too unstable for even smaller monkeys. Although male tamarins are generally larger than females (both as juveniles and adults), they show none of the dominant behavior common to other primates. Neither sex displays the typical nervous or “flitty” behavior seen in other small monkeys, and are able to respond instantaneously with quick, precise movements when circumstances warrant it. Additionally, the emperors’ unique coloring and characteristic drooping “mustache” make for excellent camouflage among the variegated tree leaves, and is believed to contribute to their social status.
Well adaptive
The South American tropical rainforest is a hot, moist land which has existed for nearly 100 million years. Centralized around the Amazon basin of northwestern Brazil, Peru, and Bolivia, it covers nearly 1.5 million square miles (3.88 million square kilometers). This unique ecosystem is almost entirely covered with giant trees which are home to a vast array of animal and plant life; 50% of all the world’s plant and animal species by some estimates. (Five hundred years ago, that number was closer to 75%.) Scientists believe that a typical four square-mile patch of rainforest contains up to 1,500 species of flowering plants, 750 species of trees, 400 species of birds (one-fifth of all the world’s bird population), and some 30 million species of insects--including 150 species of butterflies alone. Many of these species are indigenous to this specific area and exist nowhere else in the world.
With temperatures hovering near 95 degrees Fahrenheit (35 Celsius) during the day and 70 degrees Fahrenheit (21 Celsius) at night, and annual rainfall between 80 and 400”, this part of the world has no seasonal changes, meaning flowers and fruits are produced year-round. And like all tropical rainforests around the globe, this ecosystem is almost completely dependent on the massive trees that inhabit it, with much of the annual rainfall the result of moisture evaporating from the vast tree canopies and falling back to the rainforest floor. Thick mists can be seen rising above the trees each night and early morning--evidence that this life-affirming cycle continues.
Depending on location, the environment within the rainforest can be quite different due to the varying amounts of sunlight that can filter down through the thick canopy overhead. On the rainforest floor where only 2% of the light can generally reach, ground cover is virtually non-existent, the soil nutrient poor--all leaves, carrion, and animal droppings being quickly broken down by insects such as cutter ants and termites, and directly absorbed back into the surrounding vegetation. Massive tree roots grow in thick tangles above the ground in these areas, keeping the depleted soil from washing away during the frequent downpours. In brighter areas such as that illustrated above, trees, saplings, vines, and smaller plants grow so lush that it’s nearly impenetrable except by ground mammals (such as ocelots, giant anteaters, peccaries, capybaras, and Maned wolves), and reptiles and amphibians (like iguanas, boas, coral snakes, and frogs like the poison arrow). At waters’ edge you can readily find caiman, anaconda, and a variety of other well-adapted reptiles patrolling their prized niches. But it is in the trees above that most rainforest life takes place.
In the lower canopy of the forest (which extends up to about 70 feet/21 meters above the forest floor), many tree-dwelling mammals such as sloths, didelphid possums, larger monkeys like howlers, and weasels make their homes. Jaguars, ocelots, and other jungle cats are frequently seen in the lower branches, perfectly poised to pounce on unsuspecting tapir or deer as they forage the thickets below. In the middle canopy (which extends to about 100 feet/30.5 meters above the floor), several varieties of monkeys, bats, lizards, tree snakes, and a vast array of birds such as fly catchers, pigmy owls, huatzins, hummingbirds, and toucans can be found competing for food. And in the upper canopy (which extends as high as 230 feet/70 meters or more above ground level), a great many species of larger birds (such as eagles and macaws), small reptiles (a veritable army of lizards), and most smaller species of monkeys can be found filling the sprawling branches. All levels of the forest live in an interdependent web of niches, each related to those above and below. This is the world into which the emperor tamarin has adapted. But unlike its primate brethren, it has learned to exploit all four domains of the rainforest with relative ease.
Rainforest primate society
The rainforest of South America is home to a great selection of monkeys including capuchins, wakaris, white-faced sakis, spider monkeys, pigmy marmosets, owl monkeys, Goeldi’s monkeys, titis, and several species of tamarins including brown mantled, saddlebacks, and emperors. Although monkeys are considered the most social of all mammals, it can easily be said that emperor tamarins’ adaptive strategies have made it the most socially successful of all primates living in this exotic environment. While rainforest monkeys typically live in groups of 10-12 who feed, mate, and protect their young as a cohesive unit, most groups seem to prefer to inhabit individual niches which they readily defend against other monkeys--including invading troops of their own species.
Emperor tamarins, however, not only maintain tight group unity, they also establish close-knit relationships with other tamarin groups, as well as maintain long-lasting mixed-species associations with other primates with whom they routinely feed, forage, travel, and defend common feeding ranges. Additionally, emperor tamarins typically learn the signaling systems of other monkeys in order to stay alerted to food supplies and common enemies such as the large weasel-like mammal, the tyra, and predatory birds like the harpy eagle.
Like most monkeys, the tamarin diet consists primarily of flowers, fruits, insects, sap, small lizards, and the occasional bird egg. But with the special ability to distinguish plants from great distances (that would appear identical to the human eye while one is poison and the other, highly tasty and nutritious), the special arrangements they maintain with other mammals (like the pigmy marmoset that controls tree gum supplies), and the mixed-species good-will co-ventures they initiate, emperors not only enjoy a high level of feeding options, their special adaptive prowess makes for exceptional social relations for all those involved. With this highly organized (and quite intelligent) social system, the various monkey troops need not waste time or energy visiting feeding spots only to discover that another troop has already beat them to it. Instead, these mixed-species troops feed side by side, moving from feeding spot to feeding spot in coordinated tandem. And while tamarins seldom need to venture far from their niche, they are known to utilize other niches throughout the rainforest ecosystem--and sometimes seem to explore driven merely by curiosity.
Inside the primate circle
Rare among primate societies, it is the female who dominates among emperor tamarins. Living a polyandrous mating system with 10-12 unrelated adults typically constituting a group, males generally outnumber females 2-3 to 1, with males always taking responsibility for the rearing of offspring. It is the eldest female who usually leads the group, often maintaining mating relationships with all the males of her harem. Females usually giving birth to twins, requiring the males of the troop to care for the offspring (for a minimum of three months), which involves carrying them on their backs and delivering them to the mother for nursing while she is off on frequent feeding excursions taking in the nourishment she requires to produce milk. Throughout the course of a typical day, females can be herd chattering to the males (conveyed in a series of little chirps) as if to instruct them of their responsibilities while they’re away with the feeding parties. Although grooming is an important social behavior among many primates, it does not seem to be the case among tamarins, though they do appear affectionate.
Mating
Within this polyandrous society, it is the female who decides when, where, and with whom mating will take place. Using her tongue to signal sexual interest, the female simply makes a specific chirping sound followed by the sticking out of her tongue at the male she wishes to engage her. Showing no apparent partiality or long-term preference, tamarin females usually mate with two or more males in the course of a given day (quick, non-aggressive trysts on a leaf-covered tree limb) whether in heat or not, which helps maintain unity among the troop as each male assumes responsibility for the offspring that result.
Tamarin females enter estrus twice yearly, with gestation taking between 140 to 145 days. Since tamarins commonly give birth to twins (triplets are not uncommon) and usually live for 15 years or more, a female may produce 60 offspring throughout the course of her lifetime.
Final notes
While the emperor tamarin can be viewed in captivity in zoos and preserves around the world, it’s important to acknowledge that only in the wilds of the rainforest does it encounter the variety of stimuli that motivates the array of adaptive behaviors it has developed. Only among the vast array of social niches that exist in the rainforest--where countless random interactions and variables come into play--can the tamarins’ special adaptations be truly appreciated. Although all primates of the rainforest display remarkable adaptation, overcoming challenges we humans would be hard-pressed to master, the emperor tamarin does so with particular facility and what one might be tempted to refer to as finesse. And while natural beauty is often what initially attracts us to creatures such as these, it should be noted that the emperor tamarin is not just another pretty face
