Red-backed Squirrel Monkey (Saimiri oerstedi)


MORPHOLOGY:
The red-backed squirrel monkey has a short digestive tract indicative of insectivory. The cheek teeth have large cusps assists the common squirrel monkey in eating insects (Fleagle, 1988). Males have longer canines than the females (Fleagle, 1988). The tail of the red-backed squirrel monkey is prehensile in infants but the adults lose this ability. The body has a long trunk and hindlimbs and also possesses a long tail (Fleagle, 1988). The average body mass for males is 829 grams and for females it is 695 grams (Ford and Davis, 1992).

RANGE:
The red-backed squirrel monkey is found in Western Costa Rica and Panama (Kinzey, 1997). This species prefers rainforests, and can adapt to different kinds of rainforests. This species especially prefers forests with early stages of successional growth (Kinzey, 1997).

ECOLOGY:
The red-backed squirrel monkey is considered both frugivorous and insectivorous, preferring berry-like fruit on terminal branches. They also forage for molluscs, and small vertebrates, such as tree frogs. They obtain a majority of water from the foods eaten, and will also obtain water from holes in trees and puddles on the ground. This species sleeps in the canopy of emergent trees, and the group sleeps in the same tree or trees for consecutive nights (Kinzey, 1997). This species is diurnal and arboreal.

LOCOMOTION:
The red-backed squirrel monkey travels through the forest quadrupedally on the branches and leaps when it moves in the lower stories of the forest (Fleagle, 1988). This species uses quadrupedal positions when it feeds (Fleagle, 1988).

SOCIAL BEHAVIOR:
In this species females do not have alliances or dominance hierarchies (Kinzey, 1997). The group social system is multimale-multifemale and there is little aggression between the male members of the group (Kinzey, 1997). Males of this species disperse and females are philopatric (Kinzey, 1997).

VOCAL COMMUNICATION:
chuck calls: For female red-backed squirrel monkeys these calls communicate spatial and foraging context within the group (Boinski and Mitchell, 1997).

OLFACTORY COMMUNICATION:
urine-wash: This is when a red-backed squirrel monkey will spread urine on the bottoms of the hands and feet. Then when the individual walks, the urine is spread upon the substrate. It is used to spread olfactory cues.

VISUAL COMMUNICATION:
penile display: This when a male red-backed squirrel monkey places his hand on the back of another male, then turns the leg and thigh out so that the male can see his erect penis. This display is used to maintain dominance. The dominant male sometimes thrusts his penis at the other male, and even will urinate on the subordinate male.

TACTILE COMMUNICATION:

REPRODUCTION:
The red-backed squirrel monkey gives birth to a single offspring. Males gain body mass during the breeding season, up to 222 grams (Kinzey, 1997). Females in the group synchronize their births so that they all occur within a one week period (Kinzey, 1997).

REFERENCES:
Boinski, S. and Mitchell, C.L. 1997. Chuck Vocalizations of Wild Female Squirrel Monkeys (Saimiri sciureus) Contain Information on Caller Identity and Foraging Activity. International Journal of Primatology Vol. 18, 975-993.

Burton, F. 1995. The Multimedia Guide to the Non-human Primates. Prentice-Hall Canada Inc.

Fleagle, J. G. 1988. Primate Adaptation and Evolution. Academic Press.

Ford, S.M. and Davis, L.C. 1992. Systematics and Body Size: Implications for Feeding Adaptations in New World Monkeys. American Journal of Physical Anthropology Vol. 88(4), 415-468.

Kinzey, W.G. 1997. Saimiri. in New World Primates: Ecology, Evolution, and Behavior. ed. Warren G. Kinzey, Aldine de Gruyter, New York.

Last Updated: May 11, 2007.
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