Geographic Distribution and Habitat
Wied’s marmoset, also known as the Wied’s black-tufted ear marmoset, is a New World monkey that lives in the coastal regions of Southwest Brazil.
Wied’s marmosets are adaptable monkeys and can live in a variety of forest types, but they prefer tropical and subtropical forests. They occur in lowland and sub-montane humid forest as well. Occasionally, they occupy cocoa plantations with remaining native trees from original forests. They have also been found in secondary forests and abandoned rubber plantations.
Size, Weight, and Lifespan
The Wied’s marmoset is relatively small: their body measures 8–8.5 in (20.2–21.6 cm) and their tail measures 11–12 in (27.9–30.5 cm). They weigh just under one pound, between 0.66 and 0.88 lb (10.6–14 oz).
Wied’s marmosets have a lifespan of 10 to 16 years in the wild and up to 20 years in captivity.
The Wied’s marmoset is mostly black with gray head pelage. They have distinctive white fur markings around their cheeks and forehead, and black tufts of hair around the ears. They have grayish black and white stripes on their entire tail. Their tails are non-prehensile; that is, they are used for balance, not to grasp on branches.
Their hands are perfectly designed for gripping and grasping with slender, long phalanges and long nails, similar to claws.
Wied’s marmosets eat fruits, flowers, plant exudates (gums, saps, and latex), frogs, snails, lizards, and insects. During the wet season, they consume more fruit and flowers, while in the dry season more exudates are consumed.
Marmosets have an interesting adaptation for gouging tree trunks, branches, and vines. They have specialized teeth for gouging holes into tree bark for sap and other exudates.
Behavior and Lifestyle
Wied’s marmosets are arboreal and diurnal. They move quadrupedally through the forest and often leap from tree to tree. Their agility is similar to that of a squirrel, including leaping, hopping, and running. They travel about 0.5–0.75 miles (830–1200 m) a day for food. While traveling, golden-headed lion tamarins (Leontopithecus chrysomelas) often join Wied’s marmosets in search of food. They have a sympatric relationship and do not fight with one another. The marmosets tend to forage in the middle and lower parts of the canopy, while the tamarins forage higher in the canopy. Both of these monkey groups benefit from this relationship because there are additional eyes above and below the trees to watch for potential predators and to receive early warning calls.
Groups engage in scent marking, most likely to mark their territory and ward off other primate species. They mark their territory by rubbing secretions from their suprapubic region onto branches, vines, leaves, and other areas.
Wied’s marmosets’ thumbs are not opposable.
Marmosets can give birth to non-identical twins, which is an unusual trait for primates.
Wied’s marmosets are sometimes kept as pets, but they are very difficult to care for. For example, they require a very specific diet and access to UV light to stay healthy.
Wied’s marmosets are highly social creatures. Thirty minutes after sunrise, they feed intensely for about an hour, then spend the rest of the day, grooming, resting, playing, and feeding. They tend to stay within their home range of approximately 1,077 square feet (100 square meters), but they can travel up to 0.75 miles a day to forage. Their home range is based on the density of gum trees (or exudates) in an area. An hour before sunset, they return to sleeping sites of dense, vine-covered vegetation. Groups sleep together to have increased protection against predators such as hawks, snakes, jaguars, and ocelots. Wied’s marmosets’ main defense against predators is speed, and they may gang up on a smaller predator to chase it away.
Unlike other marmosets, Wied’s marmosets live in groups consisting of 4 or 5 females and 2 or 3 males, plus their children. Everyone in the group assists with childcare for the infants born each year. Younger siblings in the family learn new skills from older siblings, who help with their upbringing. Female infants grow up and stay within the group while males typically leave when they reach sexual maturity at about 1 year after birth.
Wied’s marmoset groups have a matriarchal social system in which females are dominant and have first access to resources and mates.
Wied’s marmosets use visual cues, olfactory signals, and vocalizations to communicate. When a group member feels threatened, they use alarm calls that are either staccatos or a series of short, trickling calls. These calls are also used when a group member is trying to warn the rest of the group or is fleeing from a potential danger.
General vocalization includes trills and phee calls. Trill calls are low-pitched and fluctuate in frequency. They are mostly used to track group members, especially in low visibility. Phee calls are loud and high-pitched. This call also plays a role in locating individuals, particularly a lost group member. It is also used to maintain group cohesion, for territorial defense, and to attract mates.
Visual cues are important for close-range communication. Certain facial expressions, such as partial mouth opening (signals alarm), frowning face (signals aggression), or stares (signals submissive behavior), all play important roles in communication. Other expressions like flattening ears close to the head can indicate submissiveness, fear, or curiosity.
Scent glands on the marmoset’s chest and genital/anal region allow them to mark territorial boundaries, signify social status, or advertise reproductive status. Marmosets are able to process chemical signals from a specialized organ in their nasal cavity. This allows them to recognize olfactory cues left by other animals.
Besides being matriarchal, groups are also considered to be polyandrous, where females have multiple mates. Having multiple mates, the father is not known, thus all males help in caring for the infant after he or she is born. Only the dominant female in the group breeds since the investment of the young is so high, but the dominant status is always changing between females. The dominant female enters estrus 5–12 days after giving birth; this means that they are fertile and ready to mate again. Females can give birth up to two times a year and offspring are always born in pairs—a rarity in most other primate species, but not for marmosets.
After the female gives birth to twins (which comprises up to 25% of her body weight) she receives help from other group members. Males carry the babies, while females search for food. Other members share food with the infants as well. After about 4 to 6 months, the infants are able to feed themselves; however, they still cannot gnaw their own tree holes for exudates. Until they are able to gouge trees, they lick gum or sap from holes created by other individuals.
The holes that marmosets make when gouging tree bark provides sap for other animals. Wied’s marmosets also play a role in pollination and seed dispersal, as seeds and flowers are a large part of their diet. They travel throughout the day, pollinating many plants and dispersing seeds through defecation.
The Wied’s marmoset is classified as Vulnerable by the International Union for Conservation of Nature (IUCN, 2015). Though the total remaining population of Wied’s marmosets are not known, their population is declining. A reduction of at least 30% over 18 years is suspected based on habitat loss and the ongoing capture of them for the pet trade.
Habitat loss and forest fragmentation is the main threat to Wied’s marmosets. This is due to the expansion of cattle ranches and extensive agriculture within their range. Forest fragmentation is most severe in the western part of their range. Other threats include hybridization with invasive marmoset species such as the common marmoset (C. jacchus) and the black-tuffed marmoset (C. penicillata). In addition, Wied’s marmosets are also captured for the pet trade and suffer mortality from road accidents and electrocutions.
Wied’s marmoset occurs in several protected areas such as Una Biological Reserve, Serra do Conduru State Park, Serra das Lontras National Park, and Una Wildlife Refuge. They are also present in other “non-official” protected areas such as: Lemos Maia Experimental Station (CEPLAC/CEPEC), Canavieiras Experimental Station (CEPLAC/CEPEC), and Djalma Bahia Experimental Station (CEPLAC/CEPEC). Wied’s marmoset is listed in Appendix II of the Convention on International Trade in Endangered Species (CITES).
Additional research is needed to ensure proper conservation techniques for the Wied’s marmoset. More land and site management and revised land-use policies are needed to increase the protection of this marmoset species and the ecosystems where they are native.
Written by Tara Covert, September 2020