Black-Tufted Marmoset, Callithrix penicillata
BLACK-TUFTED MARAMOSET
Callithrix penicillata
Geographic Distribution and Habitat
The black-tufted marmoset, or black-pencilled marmoset, is commonly found in a range of habitats, from the Cerrado of east central Brazil, recognized as the world’s most biodiverse savanna, to the tropical Atlantic Forest along the Brazilian coast, the second most biodiverse rainforest following the Amazon, and the dry shrubland of the Caatinga in northeastern Brazil. They are native to the Brazilian states of Bahia, Minas Gerais, Goiás, Mato Grosso do Sul, the Federal District, the southwest tip of Piauí, Maranhão, and the north of São Paulo. They have also been introduced in the more southeastern states of Brazil, including Espirito Santo, Rio de Janeiro, Paraná, and Santa Catarina, as a result of the pet trade.
Black-tufted marmosets do well in secondary growth forests that have regrown after human disturbance, and some groups have even established themselves successfully in urban areas. Black-tufted marmoset groups have been found established in backyards, parks, gardens, and plantations.
Previously, all marmosets found in eastern Brazil were considered subspecies of the common marmoset, along with the white-headed marmoset, the buffy-tufted-ear marmoset, and the buffy-headed marmoset. The decision to classify the eastern Brazil marmosets as individual species has been highly debated and remains controversial, for some species more than others. Researchers made the decision to elevate the black-tufted marmoset to a distinct species based on differences in dental and cranial morphology.
Size, Weight, and Lifespan
Both male and female black-tufted marmosets have a head and body length of 7.87 inches–9.06 inches (20 cm–23 cm), and a tail length of 11.42 inches–12.99 inches (29 cm–33 cm). While measuring the same size, males tend to be a bit heavier with an average weight of 0.76 pounds (0.34 kg), while females weigh, on average, 0.68 pounds (0.31 kg).
It is unclear exactly how long black-tufted marmosets live in the wild.
Appearance
These small primates almost resemble squirrels due to their small size. Their head and shoulders are cloaked in black fur, with matching tufts by their ears, giving them their name. Their cheeks are gray, and the black fur on top of their head is contrasted by a white spot—sometimes referred to as a “blaze”—on top of the brow ridge. The pelage (or fur) on their dorsum (or back) is gray in color, mottled with black markings that match the ringed fur on their tail. The fur on their hind legs and feet is light brown.
Diet
Black-tufted marmosets primarily eat gum (or exudates) from tree trunks, branches, and vines, which make up around 70%-80% of their diet. Relying on gums rather than fruit, like many other primates do, allows marmosets to utilize habitats that may be poor in resources (such as savannas) and highly disturbed or otherwise humanized landscapes. To access tree exudates, marmosets have specialized lower incisors and the ability to open their jaws particularly wide to gouge into tree bark. While gum is a great resource for its energy density, including key minerals such as calcium and proteins, many mammals lack the ability to digest it properly. To overcome this, marmosets have evolved longer, more complex intestines, allowing for a longer digestion time and for microbial fermentation to occur, helping to break down the gums.
They also eat nectar and flowers, fruits, as well as insects for some extra protein, and have even been observed eating lizards, frogs, eggs, newly hatched birds, and, on rare occasions, doves and mice. Their range in potential prey reflects the flexibility of their diet, which helps them adapt to so many environments. Some researchers have noted that marmosets are more likely to feed on larger prey such as birds in urban habitats, and hardly ever in their natural environment.
In urban areas, marmosets often receive supplementary food from humans who believe the small primates are “starving”. These handouts often include foods that marmosets wouldn’t typically eat in the wild, such as bananas.
Behavior and Lifestyle
Black-tufted marmosets climb, leap, and cling between the sides of trees (also known as vertical clinging and leaping) as well as walk quadrupedally (on all fours) across the tree branches. They are arboreal and rarely descend to the ground. They are diurnal, being active during the day and sleeping at night in a select rotation of tall sleeping trees that the group has deemed safe enough from potential threats during the night.
Because marmosets tend to have only one breeding male and female, agonistic interactions between males are fairly low, but when they occur, they can include chasing and lunges at the recipient of the aggression. Intergroup encounters (when two different groups meet) typically don’t result in fighting between the two groups, although they make sure to keep an eye on each other to make sure no one tries anything funny.
Black-tufted marmosets have been known to hybridize with the common marmoset and the white-headed marmoset where their ranges overlap or in areas where one or both species have been introduced.
Black-tufted marmosets live in large family groups of 4–15 individuals, which typically include multiple males and females. Their home ranges can be fairly large, ranging from 0.005 square miles–0.07 square miles (1.25 ha–18.5 ha).
Groups will typically have one breeding male and female, with the female being dominant over other group members, which she maintains by behaviorally “checking” the other females through vocalizations and visual signals. In addition, researchers think pheromones spread when the dominant female marmoset scent marks, also play a role in maintaining her social status. While there is a clear dominant female, there has yet to be a detailed study on the hierarchy of female black-tufted marmosets. There has been no clear dominance hierarchy identified for male black-tufted marmosets
Like many primates, black-tufted marmosets use vocalizations to communicate in social situations, such as whirrs, cheeting, and loud shrills to keep track of other group members’ location, chirping when in close affiliative contact with another individual, and ehr ehr vocalizations to show aggression, typically received with nga nga vocalization as a sign of submission. They also have different alarm calls to warn other group members of potential threats, such as birds of prey, dogs, and unknown humans. Low-level threats are alerted with a see sound, while more serious threats elicit seeps, tsks, and twitters. Intergroup interactions will typically receive eks and cackles to let the other group know not to mess with them.
Olfactory communication via scent-marking is done by rubbing scent glands and sometimes urine on branches or other surfaces. Researchers aren’t 100% sure of the function of scent marking in marmosets, but it is likely multifaceted. Some researchers suggest it may help the breeding female communicate and maintain her dominance, as well as allow the group to send other signals between each other and to nearby marmoset groups.
Despite their small size, black-tufted marmosets typically give birth to twins (although singlets and triplets can also occur) after a five-month gestation period. The breeding female will typically produce two litters per year, typically conceiving within a month of giving birth to her previous litter.
Females (the dominant ones at least) have concealed ovulation, meaning there are no visual signals when the breeding female is ready to conceive (although they may communicate reproductive status through scent marking or other olfactory cues that human observers are unaware of).
As mentioned, only the dominant female ovulates and thus is the only one capable of giving birth. Researchers believe this is also a part of how the dominant female’s pheromones play a role in maintaining her dominance by suppressing the ovulation of subordinate females. Researchers have also noted that female marmosets will not ovulate when in the same group as related males. This reflects one of the likely reasons for marmosets’ social structure: reduced risk of inbreeding by forcing daughters (and sons) to find a new group for breeding opportunities. Both sexes will emigrate from their original group once they mature in an attempt to find a new group where they may be able to breed. Females may sometimes “float” amongst groups while waiting for the position of breeding female to open up.
Having a single breeding couple is also beneficial to the group, as having a lower number of infants allows for higher parental care with the help of all group members, which mitigates some of the costs of infant care for marmosets such as bearing the weight of carrying such a large infant (in comparison to the size of the mother). All group members, especially the males, will help in caring for the breeding couple’s offspring, which is known as alloparenting. Strong competitors for the title of “super dads” among primates, male marmosets will often carry infants while the mother is able to forage freely, without a (relatively) large baby to carry around. In fact, the mother really only carries her babies when it’s time to nurse them.
Because there is only one breeding female and male in a group, black-tufted marmosets have been labeled as monogamous—although researchers have observed males sneaking away from their group to mate with the dominant female of another group.
The specific ecological role of black-tufted marmosets has yet to be studied, but we can make some guesses based on what we do know about them. Because they consume some fruit, they possibly acted as seed dispersers like many other primate species, contributing to the overall biodiversity of their ecosystems. Because they also sometimes eat nectar from flowers, they may also act as pollinators by inadvertently picking up pollen on their face while eating the nectar from one flower, and subsequently transporting it to the next. While further research is needed to confirm exactly the role black-tufted marmosets play, there’s no doubt they’re an important part of the ecosystems they’re native to.
The black-tufted marmoset is classified as Least Concern by the International Union for Conservation of Nature (IUCN, 2015), appearing on the IUCN Red List of Threatened Species. Their population size is predicted to be decreasing. Although common where they are found, it is believed the black-tufted marmoset’s habitat is shrinking due to habitat loss from urban and agricultural developments. In urban areas, black-tufted marmosets are also at risk of electrocution while traveling across power lines in place of a forest canopy. Urban dwelling marmosets are also at risk from car accidents, human retaliation, and predation from domestic animals.
The black-tufted marmoset’s habit of hybridizing with other marmoset species also poses a problem. While hybridization can at times be beneficial, particularly to species with severely depleted populations (which is not the case here), it can also lead to the extinction of the parent species. Hybrids are not always as fit as their parents, and may not be successfully able to breed—thus representing wasted breeding potential for the parent species as they are essentially a reproductive “dead end”. Hybrids may also become more prominent than the parent species and eventually replace them entirely.
While the species has been impacted by deforestation and the pet trade, the black-tufted marmoset has a wide distribution in various ecosystems. Their popularity as pets has created the opportunity for them to be introduced to regions of Brazil that they are not native to by either being released or escaping. This, combined with their generalist nature and ability to easily adapt to various habitats has allowed the black-tufted marmoset to become established and considered invasive in these areas. While this may sound beneficial to the black-tufted marmosets, who are losing their native habitats, it is detrimental to the local wildlife. The black-tufted marmosets are often able to outcompete the native marmosets and tamarins in their introduced regions for space and food. They also pose as possible disease transmitters to local human and non-human primates. Marmosets have been classified by the National Health Foundation of Brazil as a host species and possible biological risk parasite reservoir, and are monitored by the Surveillance and Control Coordination of Biological Risk Factors. Marmosets have been known to carry rabies and have transmitted it to humans, along with yellow fever and intestinal parasites. Their flexible diet that has been observed to include eggs and birds also poses a threat to the native birds, as well as reptiles and amphibians, in their introduced regions.
Black-tufted marmosets are 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.
In urban areas where marmosets have higher interactions with humans, researchers call for education efforts to help local people better understand the biology of marmosets and that feeding them is, while well-intentioned, unnecessary. Law enforcement is often called in response to aggressive marmosets—typically as a result of the marmoset having been fed by humans. Captured animals are sometimes put into zoos or relocated to a green area away from the site where they were captured. Often, the release site is too far away for the marmoset to rejoin their original group, putting the individual in danger. Researchers also call for the education of local authorities to ensure they are able to respond to human-marmoset conflicts appropriately.
Researchers also call for the implementation of safer power lines to reduce electrocution risk to marmosets, such as the use of safe coated conductors.
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Written by Lina Rademacher, Jul 2025