Geographic Distribution and Habitat
The white-headed marmoset is also known as the tufted-ear marmoset and Geoffroy’s marmoset, or Geoffroy’s tufted-ear marmoset. The species is endemic to Brazil, where they are known as the sagüi or sauim. They are present in the state of Espirito Santa and in the forested eastern and northeastern regions of Minas Gerais, extending north as far as the Rios Jequitinhonha and Aracuai, as well as south to near the state border of Espirito Santo and Rio de Janeiro. The population of white-headed marmosets south of Rio Jequitinhonha was introduced there in 1975. This population has since spread eastward.
White-headed marmosets live in lowland forests, sub-montane forests, and dry forest patches in desert scrub. They inhabit a wide variety of habitats such as dense forests, semi-deciduous forests in the Atlantic forest biome, and deciduous forests in the Caatinga biome. They are tolerant to changes and environmental disturbances; thus, they can be considered a well-adapted species to anthropogenic environments, where there is human activity.
Size, Weight, and Lifespan
White-headed marmosets are small primates measuring about 7.8 in (19.8 cm) in length. Females weigh only 0.4 lb (190 g), while males weigh 0.5–0.8 lb (230–362 g). Their tails are longer than their body length, measuring at 11 in (28 cm).
The typical lifespan for white-headed marmosets in the wild is about 10 years.
White-headed marmosets are mostly black and dark brown in color. Their tail is lightly ringed with gray and black bands. Adults have white heads, cheeks, and throats. Adults also have black tufts of fur by their ears.
Infants lack ear tufts and white markings around their face. At about two weeks of age, juveniles begin to grow their ear tufts and have full adult markings by 5 months.
Marmosets (and tamarins) are distinguished from other New World monkeys by their small size and modified claws, rather than nails, on all digits except their big toe. They also possess two molar teeth on each side of the jaw rather than three.
What Does It Mean?
A recurring period of sexual receptivity and fertility in many female mammals.
A substance, such as gum, sap, or resin, which flows from the vascular system of a plant.
A mammal of the wild cat family.
An equatorial evergreen rainforest, commonly known as a tropical rainforest, which receives high rainfall (80 in, or 2 m) throughout the year.
Having only one sexual partner.
Carnivorous mammals including weasels, badgers, otters, ferrets, and mink, among others.
a chemical substance secreted or excreted into the environment by an animal that triggers a social response in members of the same species.
A forest that is situated at the foothills or lower elevation slopes of a mountainous region.
Understory layer (of the rainforest):
The third layer of the forest, above the forest floor. Little sunshine reaches this area, so plants must grow larger leaves to reach the sunlight. These plants seldom grow to 12 feet.
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White-headed marmosets are omnivorous, eating fruits, flowers, nectar, and insects. They will also eat small animal prey such as snails, lizards, and frogs. Marmosets have behavioral and morphological adapatations for gouging tree trunks to extract plant exudates such as gum and sap. Their claws allow them to cling onto the side of trees and gnaw off bark with their incisors, then scoop out the gum or sap with their fingers.
Behavior and Lifestyle
White-headed marmosets are a diurnal and arboreal species. They are climbing specialists and adequate leapers. Their typical locomotive behaviors involve quadrupedal running (on all fours), vertical clinging, and leaping on branches. The evolutionary replacement of nails with claws is an environmental adaptation that assists in their locomotion.
These primates spend most of their time resting (about 30%) and feeding (20%). During the dry season they spend less time resting (17–18%) and more time foraging for food (21%). Due to their small body size, marmosets consume insects to fulfill their protein intake and fat requirements. Marmosets are often found in the understory of the forest, silently stalking and pouncing on large mobile insects.
Their home ranges—which are centered around patches of gum trees—are between 0.04–0.15 sq mi (0.1–0.4 sq km), based on the density of the gum trees. Their daily range averages between 0.30–0.62 mi (0.5–1 km).
During the day, marmosets are active for 11–12 hours from sunrise to sunset. After awakening and leaving their sleep site, they feed for about one hour and then spend the rest of the day alternating between resting, feeding, and socializing.
At the end of the day, typically right before sunset, they settle into deep vine-covered vegetation for sleeping sites. The group sleeps together for safety from predators, which include felids, snakes, owls, raptors, and mustelids.
Daily Life and Group Dynamics
Group size and composition varies from troop to troop. Family groups average between 8 and 10 individuals but can be as large as 18 individuals. Group composition may be multi-male/multi-female, one-male/multi-female, or one-female/multi-male. Groups are led by one monogamous pair, who are the highest-ranking male and female.
Groups are typically composed of a breeding pair and their offspring. Occasionally groups may include 1 or 2 “immigrants” from other groups.
White-headed marmosets follow army ant swarms, which attract many organisms up toward the trees.
Marmosets are among the few primate species that regularly give birth to twins.
White-headed marmosets use tactile, visual, and vocal communication. When a threat is perceived, they emit alarm calls. These calls include “staccatos” and “tsiks” as well as high-pitched vocalizations. Other calls include very loud, high-pitched whistles, and “trill” calls that are lower-pitched and are used to monitor group members and to determine location.
Play biting is common during playful interactions and is exhibited by individuals in all genders and age groups. Grooming is another common tactile form of communication and occurs mostly during times of low activity.
White-headed marmosets display various forms of visual communication, such as a bouncing gait, gallop, slide, roll, leg stand, tufts/ears flick, tufts/ears flatten, tufts/ears forward, and tail raise. The most common of these displays is the bouncing gait, in which they run with an exaggerated bounce. This is a playful demonstration. An open-mouth expression is common during play—an individual opens his or her mouth with the teeth bared. In agonistic situations the tufts/ears flick (when the tufts and ears flick back and forth) is used. Similarly, tufts/ears flatten (when the ears are flattened against the head) is a response to agonistic situations and is also motivated by fear. Tail raising is common in aggressive situations.
Reproduction and Family
The dominant male and female in a group form a monogamous bond; only this pair breeds. Reproduction in other adult female troop members is suppressed by pheromones produced by the scent glands of the dominant breeding female. This leads to a delay in reproduction in subordinate females for as long as they remain within the group. Theories suggest that female reproduction is suppressed so that those other troop members are available to assist with childcare.
Courtship begins with sniffing each other, marking objects, huddling, and grooming. These behaviors start to increase as the female reaches estrus. Twins are usually born, but sometimes a single infant or triplets may occur. The father assists with the birth and licks the babies, then gives them to the mother. Other family members may eat the placenta.
Infants nurse for 5–6 months. Unlike many other primates, a female white-headed marmoset feeds both her infants at the same time. Within the first week of being born, the father carries the twins exclusively, only handing them over to the mother to nurse. The father remains the primary carrier of the infants; however, after the first week all members of the family participate in carrying the young. Older siblings also assist in taking care of the young. This teaches the older siblings essential skills they need in caring for their future offspring.
Due to their omnivorous diet, white-headed marmosets disperse seeds and fruits throughout the forest.
Conservation Status and Threats
White-headed marmosets are listed as Least Concern by the International Union for Conservation of Nature (IUCN, 2015) due to their abundance and their presence in a number of protected areas. However, they are in a current rate of decline due to the quality of their habitat. The major threats identified are rural settlements, agriculture, livestock, and deforestation. The expansion of forestry for wood harvesting and wood/pulp plantations have led to ecosystem degradation. These threats have led to a reduction in their habitat and widespread destruction of the Atlantic Forest in the states of Minas Gerais and Espirito Santo. Less than 6.8% of the Atlantic Forest remains in the state of Minas Gerais.
The species is also occasionally hunted for the exotic pet trade.
White-headed marmosets occur in many protected areas in Minas Gerais, Espirito Santo, Bahia, and Santa Catarina such as Serra do Cipo National Park, Fazenda Córrego de Areia Reserve, Córrego Grande Biological Reserve, Córrego do Veado Biological Reserve, Sooretama Biological Reserve, Comboios Biological Reserve, Duas Bocas State Reserve, Linhares Forest Reserve, Goitacazes Forest Reserve, Santa Lucia Biological Station, Fazenda São Joaquim Reserve, Porto Seguro Forest Reserve, Pau Brasil Experimental Station, Gregório Bondar Experimental Station, and Córrego Grande Ecological Park. The species is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES).
Other conservation efforts include studies on ecology and behavior, as well as environmental education and habitat preservation. These actions are an important teaching tool for the conservation awareness of not only this species, but primate species in general. Developing an effective local community conservation program for this species can help preserve white-headed marmosets and their habitat for the future.
- Stevenson, M., A. Rylands. 1988. The Marmosets, Genus Callithrix . in R Mittermeier, A Rylands, A Coimbra-Filho, eds. Ecology and Behavior of Neotropical Primates. 2:131-222.
- Wakenshaw, V. 1999. The Management and Husbandry of Geoffroy’s Marmoset. International Zoo News, 46:1.
Written by Tara Covert, April 2019