SILVERY MARMOSET

Mico argentatus

Geographic Distribution and Habitat
The silvery marmoset is found in the Brazil’s eastern Amazon Rainforest. They typically live in primary and secondary growth lowland tropical forests; however, due to increasing habitat loss and fragmentation, this species is also found in anthropogenic habitats such as disturbed and fragmented forests. 

Silvery marmoset geographic range, IUCN, 20008

Size, Weight, and Lifespan
Silvery marmosets are relatively small primates. The average head-to-body length, excluding the tail, typically measure about 8.5 in (21.6 cm); the tail adds another 11.5 in (29.2 cm) on average. Adults weigh between 0.6 and 1 lb (273–435 g). The reported lifespan is about 16 years.

Appearance
True to its name, the silvery marmoset’s body is a striking silver-gray color. In contrast, the tail is dark brown. They have bare faces and bare ears, a trait they share with several other marmoset species. Their hands—which look strikingly similar to human hands—end in sharp claws, which they use to gouge tree bark to access and consume the sticky sap inside.

Silvery marmoset (Mico argentatus). Wild life animal.

What Does It Mean?

Allogrooming:
Social grooming within a species.

Alloparent: 
An individual other than the biological parent of an offspring that performs the functions of a parent (as by temporarily caring for an infant).

Anthropogenic:
Of, relating to, or resulting from the influence of human beings on nature. Often refers to pollution.

Gestation:
The time of pregnancy from conception until birth.

Inbreeding:
The production of offspring from closely related individuals.

Visit the Glossary for more definitions

Diet
The silvery marmoset’s favorite thing to eat is tree sap and gum; aided by their long claws, they make a hole in the tree bark and then use their tongue and fingers to lick and scoop it out. Additionally, they feed on fruit, flowers, and the occasional small lizard, amphibian, insect, spider, or egg. Due to the high levels of gum and sap in their diets, silvery marmosets (and other marmosets and tamarins) have a specialized gut, including a large caecum that slows digestion, which helps them to absorb the nutrients from these food sources.

Behavior and Lifestyle
Silvery marmosets are a primarily arboreal species and may spend their entire lives in the trees, never once coming down to the ground. Their range is smaller than some other marmoset species, about 25 acres (10 ha). Silvery marmosets are diurnal and spend their days foraging throughout their home range with their family group. As the sun sets, they find a place to sleep, often a vine tangle or tree hole, were they are nestled together and safe from predators.

 Daily Life and Group Dynamics 
Silvery marmosets live in groups of 4 to 12 individuals, one of whom is the dominant and sole reproducing female. Groups stick together and are relatively cohesive. Allogrooming is a frequent occurrence among all members. Levels of aggression are relatively low and aggressive bouts are mild, occurring most often around feeding times and feeding sites. When they reach maturity, both males and females tend to disperse and leave their family groups in order to find new mates.

Fun Facts

Unlike most primate species, silvery marmosets have sharp claws instead of nails.

Silvery marmosets (M. argentatus) and other marmosets have a specialized dentition and morphology for gouging tree bark—their lower incisors are sharp and chisel-like to allow them access to tree exudates (gums, saps, latex, and resins).

Communication
As with many marmosets and tamarins, communication is important and complex in this species. They use specialized calls to convey messages in varying situations. Similar to human language, marmoset vocalizations can be used to signal aggression, passivity, dominance, submission, and intention. For example, when initiating play and throughout a play session, silvery marmosets make a “ee-ee” sound, but when alerting other group members to a potential threat, they use a high-pitched, rapid “tsik” call. 

In addition to vocalizations, silvery marmosets also utilize scent communication. They have specialized glands on their chests and genitals that they use to convey messages about territories, dominance, and reproductive status by rubbing the glands on tree branches, leaving the scent behind.

Reproduction and Family
Silvery marmosets reach sexual maturity by age two and breed twice a year—although typically only the dominant female in a group breeds. Reproduction in other females in the groups is suppressed. These marmosets have a gestation period of 145 days, after which they usually give birth to twins. These twins are often dizygotic, meaning that they are not genetically identical and may even have different fathers. Infant care is shared among group members, who may act as alloparents for the infant. Fathers and male group members often carry the infants and return them to their mother to feed. This alloparenting helps non-reproducing members of the group practice their parenting skills and increases the infants’ chances of survival. Infants are weened around six months of age and are adult-sized by one to two years.

Ecological Role
Silvery marmosets act as seed dispersers by depositing seeds from the fruit they eat throughout the forest. 

Conservation Status and Threats
The silvery marmoset is classified as Least Concern on the International Union for Conservation of Nature Red List of Threatened Species (IUCN, 2015). However, their populations are in decline. The primary cause of this population decline and the major threat to this species is habitat loss. The forests where silvery marmosets live have been fragmented or cut down to make way for highways, agriculture, cattle-ranching, and other human development. 

As a result of this fragmentation, many groups of silvery marmosets have become genetically isolated and have experienced inbreeding and genetic drift between populations, a result which may impact the long-term survival capacity of this species.

Conservation Efforts
Conservation efforts for this species thus far have been limited and mainly passive. These marmosets are found in several protected areas, inlcuding Tapajós National Forest and Caxiuanã National Forest. Additionally, they are listed on the Convention on International Trade in Endangered Species (CITES) Appendix II, which limits trade in this species. Future conservation efforts include researching the extent of this species’ range to better understand how habitat loss impacts them, as well as limiting habitat fragmentation and forest loss.

References:

  • Garza, R. 2001. “Callithrix argentata” (On-line), Animal Diversity Web. Accessed December 08, 2018 at https://animaldiversity.org/accounts/Callithrix_argentata/
  • Gonçalves E, Ferrari SF, Silva A, Coutinho P, Menzes E and Schneider MPC (2013) The Effects of Habitat Fragmentation on the Genetic Variability of Silvery Marmosets, Mico ArgentatusPrimates in Fragments: Ecology and Conservation. Springer Science & Business Media.
  • ​https://www.marwell.org.uk/zoo/explore/animals/55/silvery-marmoset
  • https://twycrosszoo.org/animals/silvery-marmoset/
  • https://www.shaldonwildlifetrust.org.uk/page/silvery-marmoset/
  • https://www.exmoorzoo.co.uk/animals/silvery-marmoset
  • http://pin.primate.wisc.edu/factsheets/entry/common_marmoset
  • Rylands, A.B. & Silva Jr, J. 2018. Mico argentatus. The IUCN Red List of Threatened Species 2018: e.T41520A17932745. http://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T41520A17932745.en. Downloaded on 08 December 2018.​

Written by Kylie Sorenson, December 2018