Silvery-brown tamarin, Oedipomidas leucopus
SILVERY-BROWN TAMARIN
Oedipomidas leucopus
Geographic Distribution and Habitat
The silvery-brown tamarin (Oedipomidas leucopus), also known as the silvery-brown bare-faced tamarin or white-footed tamarin, is native to Colombia. This species roams the areas close to the Cauca River and can be found on the western side of the middle Magdalena River, including all the large islands in this river, such as Mompós. Populations can also be spotted in the foothills of the Central Andean Mountain range, up to 4,921 feet (1,500 m) above sea level. They enjoy sultry weather all year round, with average temperatures ranging from 66–81°F (19–27°C).
The silvery-brown tamarin inhabits a variety of habitats, including tropical dry forests, tropical rainforests, premontane rainforests, and primary and secondary forests. It is an environmentally flexible species that inhabits areas with different levels of precipitation, ranging from light to heavy rainfall. Nevertheless, they prefer settling near streams and other water sources. In the city of Mariquita, these monkeys have learned to thrive in urban environments, making them regular guests in gardens and parks.
There are currently no recognized subspecies; however, because southernmost populations of silvery-brown tamarins are darker, there are debates about whether they may constitute a separate subspecies.
Interestingly, the species has been scientifically recategorized. Since 2021, the scientific community has abandoned the old name Saguinus leucopus in favor of Oedipomidas leucopus.
Size, Weight, and Lifespan
With an average body length of 9–10 inches (23–25 cm) and an impressively long tail of about 14 inches (38 cm), this small monkey weighs only about 1 pound (460 g). They live approximately 8 years, although in captivity they’ve been observed to live up to 17 years. There are no significant differences between the two sexes.
Appearance
Silvery-brown tamarins owe their name to their distinctive silvery pale brown fur that covers their back. Their chest and bellies are russet-colored, while their tail is brown and has a white tip. The face has sparse white hairs, while thick brown fur covers the neck and the area between the ears. Their forelimbs are significantly shorter than their hind limbs, and both their hands and feet are white. Like other tamarin species, they have sharp claws on their digits instead of nails, except on their big toes, which have flat nails. Claws help them grip branches and are an essential evolutionary advantage for a species that spends its days in the trees of the forests it inhabits.
Diet
The silvery-brown tamarin has a diverse diet, mainly consisting of ripe fruit, especially mango, which they love. Their usual menu is enriched with other plant matter such as flowers, plant fluids (gums, saps, latex), nectar, leaves, and bark, as well as protein-rich sources like insects, especially grasshoppers. They occasionally indulge in rarer delicacies such as small bird eggs, frogs, and lizards. Seldom do they forage on the forest floor, preferring the safety and comfort of treetops and lianas.
The silvery-brown tamarin has a balanced diet that changes according to the seasonal availability of food sources. Although their preferred food source is fruit, human activity has negatively impacted their feeding habits. For example, in the city of Mariquita, this species feeds on only 13 species of plants due to higher urbanization and human disturbance, while in intact areas, their diet is much more varied.
Behavior and Lifestyle
The silvery-brown tamarin is an arboreal monkey, spending the majority of its life in the trees and rarely setting foot on the ground.
They use all four of their limbs to move between branches and leap from one tree to another. They’re also excellent climbers. They rely on all four of their limbs to climb down vertically using lianas, branches, and tree trunks. Thanks to their claws, their grip is excellent, and their petite body size makes them particularly agile.
Silvery-brown tamarins are diurnal, meaning they are active during the day and sleep at night. Around 19% of their time is spent feeding, 24% resting, 1% socializing, and a whopping 56% of their day is spent moving within their home range. They move within larger and core home ranges when food is scarce, likely as a way to ensure that all group members have a fair chance at feeding.
Natural predators include different wild cat species such as the margay, Leopardus wiedii, raptors such as eagles and hawks, small predators like the tayra, Eira barbara, grisons, and the boa constrictor.
They live in small groups of around 12 individuals. Solitary monkeys have been spotted. There have also been reports of larger groups of up to 27 members. Groups are composed of (extended) family members.
Their home range varies significantly, but some studies have discovered that this species’ home range can be up to 240 acres (97 ha). There are significant overlaps between different groups’ home ranges—up to 87% of their territory is shared with other groups. Although their home ranges overlap, different groups hardly ever interact. When interactions occur, there are significant aggressive displays, such as vocalizations and chasing.
On average, silvery-brown tamarins travel 1.2 miles (1.95 km) per day. Several factors influence their daily commute, including the fact that much of their territory is shared with other groups. In fact, traveling across their home range ensures less competition and more food.
They live in an ecosystem rich in biodiversity, near other primate species like spider monkeys, Ateles spp. They are separated from a very similar tamarin species, the cotton-top tamarin, by the Atrato River.
The silvery-brown tamarin is a highly social and vocal species. They use a variety of sounds in various social and non-social contexts. Today, we know that they use around 19 different sounds associated with different behaviors.
For example, they emit two types of whistles while exploring their territory and foraging. These calls are high-frequency and quite short, making them very effective against predator detection. These whistles are probably used to keep close contact with other members of the group.
Many of their calls are associated with anti-predator behaviors. Among these is the “inverted U,” a short, high-frequency call followed by fleeing, and “Chirp A,” used to threaten predators. “Chirp A” is repeated continually and accompanied by clustering around the threatening source. “Chirp B,” instead, is shorter and slightly lower in frequency. It is used in the face of threats but also to express curiosity and possibly fear. Other threatening sounds include the “Pip” and “Piip” sounds, used by silvery-brown tamarins when they’re being aggressive and have low to no fear.
The vocalization “Chiiih A” is probably the most iconic call of this species. It is used for territorial purposes. Being long and high in frequency, it works effortlessly to maintain contact with other distant group members and inform them of the caller’s location. It has also been suggested that the length of syllables may be directly correlated to the distance between tamarins or whether males are calling to their offspring or unrelated members. A lower number of syllables may even be used to contact tamarins that belong to other groups.
“Squeaks” are emitted by attacked members, possibly as a way to show their submission and escape from more tense and dangerous situations, although the exact reason is not fully clear. Sound combinations are also used in different contexts, making vocal communication in this species highly effective.
Young vocalizations are very similar to those of adults, with the only noticeable difference being their frequency, which is usually higher. Youngsters tend to produce more affiliative sounds and fewer calls linked to aggression; moreover, they show a fascinating learning curve. They combine different and novel sounds that are later refined to resemble more closely those used by adults. It’s almost like a toddler learning a language.
Besides vocal communication, silvery-brown tamarins are also known to mark their territory with scent glands present on their body, especially localized in their genital and gluteal areas. This is another way to make their presence known and discourage intruders from attempting to take over.
Typically, a single fertile female will mate with several males, more frequently in May–June and October–November, when fruit is most abundant. In nature, she will give birth to a single baby, although in captivity, twin births are fairly common. Like in many other tamarin species, subordinate females will have their reproductive cycles suppressed—an adaptation that guarantees the dominant female’s reproductive hegemony.
The gestation period is roughly 130–150 days, and their babies will reach maturity when they are around 12–18 months old. Males also take part in caring for their offspring.
They live in tight-knit family groups, creating a support system essential to their survival. Such close relationships, in fact, are quite effective in helping them avoid predators.
This species thrives on a fruit-rich diet; thus, it contributes greatly to seed dispersal across the forest floor. They travel several miles each day, providing trees with the opportunity to spread their seeds far and wide. Such a role is essential to sustaining biodiversity and guaranteeing forest regrowth. Additionally, this species also feeds on nectar and flowers, which in turn means that it contributes to pollination, further strengthening its role as a forest protector.
The silvery-brown tamarin is classified as Vulnerable by the International Union for Conservation of Nature (IUCN, 2020), appearing on the IUCN Red List of Threatened Species.
There has been a steady population decline over the last 18 years due to deforestation and consequent habitat loss. It is estimated that around 25–30% of the existing forest that these animals inhabit will be lost by the year 2036 if action is not taken. Their habitat is being destroyed due to farming, agriculture, logging, mining, quarrying, and rapid urbanization, including road and dam construction near the Río Miel. This species is also threatened by illegal hunting and the pet trade.
Silvery-brown tamarins are listed in Appendix I of the Convention on International Trade in Endangered Species (CITES), an international agreement between governments aimed at ensuring that international trade in specimens of wild animals and plants does not threaten their survival.
Silvery-brown tamarins can be found in the regional reserve of Cañon del Río Alicante, which is unfortunately poorly protected. Another protected area where this species lives is the proposed park of the Sierra San Lucas.
There have been significant efforts to create protected areas for this species. For example, a regional captive breeding program supported by the European Callitrichid TAG (18 zoos) started in 2006. However, releasing individuals into the wild has not been as successful as initially hoped due to this species’ problematic breeding in captivity.
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Written by Mirko Cerrone, January 2025