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Saimiri sciureusSouth American squirrel monkey

By Cynthia Rhines

Geographic Range

Squirrel monkeys live in the tropical rainforests of South America, except in the southeastern coastal forests of Brazil.

Habitat

Squirrel monkeys prefer primary and secondary forest, gallery forest and forest edge.

They prefer the intermediate forest levels, but they can sometimes be found on the ground or in upper canopy levels.

They occupy many different types of forests.

Physical Description

Squirrel monkeys are up to 12.5 inches long (body length), with a tail of approximately 16 inches. They have a slender, lithe build, with a short greyish coat and bright yellow legs. Their non-prehensile tail often curls over one shoulder when they are resting. They have 36 teeth, and their teeth are sexually dimorphic in that males have large upper canines.

Squirrel monkesy possess nails instead of claws, and they have been called 'small, nervous primates'. They are the smallest of the Primate family Cebidae.

  • Average mass
    925 g
    32.60 oz
    AnAge
  • Average basal metabolic rate
    4.429 W
    AnAge

Reproduction

Within their own group, squirrel monkeys are promiscuous.

Squirrel monkeys are seasonal breeders. They mate between September and November, with birth between February and April. Gestation lasts 160-170 days. The birth season is short and occurs during the time of greatest rainfall, perhaps because the wet season brings an abundance of food and water.

Males are mature at 4 years of age; females are mature at 2.5 years of age.

  • Breeding season
    Squirrel monkeys mate between September and November
  • Average number of offspring
    1
    AnAge
  • Range gestation period
    160 to 170 days
  • Average age at sexual or reproductive maturity (female)
    2.5 years
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    1003 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    4 years
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    1826 days
    AnAge

Female squirrel monkeys nurse and care for their infants until they are independent. The fathers take no part in raising young.

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • protecting
      • female

Lifespan/Longevity

Behavior

Squirrel monkey groups may be made up of as many as 300 individuals. In the non-mating season, subgroups form within the main group based on, for instance, age, sex or family roles. These subgroups are abandoned during the mating season. Group size is affected by

habitat.

Squirrel monkeys are very agile; they often run throughout the forest on branches.

Squirrel monkeys display female dominance, with the females forming the central core of

the group, or troop.

Some temporary relationships may form between a mother with no infant and another female's infant. These older females become "aunts".

Males have a "subadult" period in while they still play with other juveniles. Males also display a clear dominance hierarchy. Males at the top of their hierarchy are not always the most successful in mating; it is unclear what the advantage of social position is.

There are no territorial disputes, groups tend to mutually avoid one another. Groups may sometimes be found together, but not for long and perhaps only to search for food.

Squirrel monkeys are diurnal, and activities are usually centered around a source of water.

Communication and Perception

Food Habits

Squirrel monkeys eat mainly fruit and some insects; they also consume some leaves and seeds. The first hour or so of the day is spent searching and collecting fruit. From then on, they look also for spiders and insects. A group spreads throughout the forest in all canopy levels to search for food.

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit

Economic Importance for Humans: Positive

Used as pets and in research.

Conservation Status

Currently, captive squirrel monkey populations are maintained in research labs.

Threats to wild squirrel monkeys include eagles in the trees and snakes on the ground.

Squirrel monkeys are easily kept in captivity, and they were once frequently sold as pets.

Habitat destruction, illegal hunting, and capture for the pet trade or medical research all pose threats and problems to the squirrel monkeys.

Contributors

Cynthia Rhines (author), University of Michigan-Ann Arbor.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Napier and Napier. 1985. The Natural History of the Primates. MIT Press, Cambridge, MA.

Kavanagh, M. 1983. A Complete Guide to Monkeys, Apes and Other Primates. Jonathan Cape, London.

Eimerl, S. and I. DeVore. 1965. The Primates. Time Life Books, NY.

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