squirrel monkey

Squirrel monkeys[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Primates
Family:	Cebidae
Subfamily:	Saimiriinae Miller, 1912 (1900)
Genus:	Saimiri Voigt, 1831
Type species
Simia sciureus Linnaeus, 1758
Species
Saimiri oerstedii Saimiri sciureus Saimiri ustus Saimiri boliviensis Saimiri vanzolini

The squirrel monkeys are the New World monkeys of the genus Saimiri. They are the only genus in the subfamily Saimirinae.

Squirrel monkeys live in the tropical forests of Central and South America in the canopy layer. Most species have para- or allopatric ranges in the Amazon, while S. oerstedii is found disjunctly in Costa Rica and Panama.

Squirrel monkey fur is short and close, colored olive at the shoulders and yellowish orange on its back and extremities. Their throat and the ears are white and their mouths are black. The upper part of their head is hairy. This black and white face gives them their German name, "skull monkeys".

Squirrel monkeys grow to 25 to 35 cm, plus a 35 to 42 cm tail. They weigh 750 to 1100g. Remarkably, the brain mass to body mass ratio for squirrel monkeys is 1:17, which gives them the largest brain, proportionately, of all the primates. Humans have a 1:35 ratio.

Female squirrel monkeys have a pseudo-penis that they use to display dominance over smaller monkeys, much like the way the male squirrel monkeys display their dominance.

Like most of their New World monkey relatives, squirrel monkeys are diurnal and arboreal. Unlike the other New World monkeys, their tail is not used for climbing, but as a kind of "balancing pole" and also as a tool. Their movements in the branches are extremely speedy.

They live together in multi-male/multi-female groups with up to 500 members. These large groups can, however, occasionally break into smaller troops. They have a number of vocal calls, including warning sounds to protect themselves from large falcons, which are a natural threat to them. Their small body size also makes them susceptible to predators such as snakes and felids. For marking territory, squirrel monkeys rub their tail and their skin with their own urine.

Squirrel monkeys are omnivores, eating primarily fruits and insects. Occasionally they also eat nuts, buds, eggs and small vertebrates.

The mating of the squirrel monkeys is subject to seasonal influences. Females give birth to young during the rainy season, after a 150- to 170-day gestation. The mothers exclusively care for the young. Saimiri oerstedti are weaned by 4 months of age, while S. boliviensis are not fully weaned until 18 months old. Female squirrel monkeys reach sexual maturity at age 3 years, while males take until age 5. They live to about 15 years old in the wild, about 20 years in captivity.

The Common Squirrel Monkey S. sciureus is captured for the pet trade and for medical research^[2] but it is not endangered. Three squirrel monkey species are in danger of extinction. S. o. oerstedti is listed as endangered, S. o. citrinellus is listed as critically endangered and S. vanzolinii is listed as Vulnerable.

Classification

Until 1984, all South American squirrel monkeys were generally consider part of a single widespread species, and many zoologists considered the Central American Squirrel Monkey to be a member of that single species as well.^[1][3] The two main groups currently recognized can be separated by the white above the eyes; it being shaped as a Gothic ("pointed") Arch in the S. sciureus group, while it is shaped as a Roman ("rounded") Arch in the S. boliviensis group.^[4]

• Genus Saimiri
  • S. sciureus group
    • Central American Squirrel Monkey, Saimiri oerstedii
      • Black-crowned Central American Squirrel Monkey, Saimiri oerstedii oerstedii
      • Grey-crowned Central American Squirrel Monkey, Saimiri oerstedii citrinellus
    • Common Squirrel Monkey, Saimiri sciureus
      • Saimiri sciureus sciureus
      • Saimiri sciureus albigena
      • Humboldt's Squirrel Monkey, Saimiri sciureus cassiquiarensis
      • Ecuadorian Squirrel Monkey, Saimiri sciureus macrodon
    • Bare-eared Squirrel Monkey, Saimiri ustus
  • S. boliviensis group
    • Black-capped Squirrel Monkey, Saimiri boliviensis
      • Bolivian Squirrel Monkey, Saimiri boliviensis boliviensis
      • Peruvian Squirrel Monkey, Saimiri boliviensis peruviensis
    • Black Squirrel Monkey, Saimiri vanzolini

Gallery

At the Phoenix Zoo.

At the Phoenix Zoo.

At the Fuji Safari park, Japan

References

External links

Wikispecies has information related to: Saimiriinae

Wikispecies has information related to: Saimiri

Wikimedia Commons has media related to: Saimiri

Wikimedia Commons has media related to: Saimiri_sciureus

• Primate Info Net Saimiri Factsheet
• [1] reforestation for the endemic Squirrel Monkey of Panama and Costa Rica