SQUIRREL MONKEY FACTS
| Family: Cebidae |
Subfamily: Cebinae |
| Genus: Saimiri |
Species: five -- |
- boliviensis (Bolivian squirrel monkey)
- oerstedii (red-backed squirrel monkey)
- sciureus (common squirrel monkey)
- ustus (golden-backed squirrel monkey)
- vanzolinii (black squirrel monkey)
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Classifications, as always, are disputed. Several subspecies have been identified.
Appearance:
Though varying in coloration, squirrel monkeys have a distinctive look, with a white mask around the eyes and a black muzzle. They are the smallest of the cebids, 10-14 inches in body length, with weight varying from 20-40 ounces. They do not have prehensile tails.
Range and Diet:
Red-backed squirrel monkeys are found in south Central America, while the rest have ranges within northern and central South America, in various forest habitats, particularly rain forests. They prefer the middle canopy for foraging. A large part of their diet consists of animal prey, especially insects, but most will also eat fruit, seeds, and leaves.
Behavior and Social Structure:
Squirrel monkeys are diurnal and arboreal. Their social system varies with the species, but they all travel in multimale-multifemale groups, with group size ranging from 20-50 (sometimes more) individuals. Females are normally dominant, with males becoming more aggressive and assertive during the breeding season. Outside of the breeding season males tend to associate more with each other than with females within their group. Some squirrel monkeys form associations with other cebus monkeys, particularly capuchins, to whom they are most closely related. They communication with a large variety of vocalizations, and some scent marking (urine washing.)
Reproduction and Lifespan:
Squirrel monkeys have a breeding season, which varies with the species to some extent, and which corresponds to increased testosterone production and weight gain in males. During this time males will form rigid dominance hierarchies and engage in penile displays. Females normally give birth to a single offspring and are responsible for the majority of infant care. Allomothering is common. There is some evidence of hybridization between black and golden-backed squirrel monkeys. There are still a lot of gaps in our knowledge of the life history of squirrel monkeys. They can live at least 20 years.
Conservation Status:
The Bolivian, common, and golden-backed squirrel monkeys are listed as Lower Risk (CITES II.) The black squirrel monkey is listed as Vulnerable (IUCN), with a 10% probability of extinction within the next 100 years. The red-backed squirrel monkey is Endangered (USESA) - there is a 20% chance of extinction in 20 years or within five of its generations. Owners of fruit orchards in the Amazon region consider squirrel monkeys pests.
Interesting Squirrel Monkey Facts:
Common squirrel monkey infants have prehensile tails. Adults do not.
The black squirrel monkey has the smallest distribution - only 367 square miles of Brazil.
While most squirrel monkeys show no sexual dimorphism, Bolivian squirrel monkeys are sexually dichromatic - with black on the females and gray on the males.
Red-backed squirrel monkeys may have been introduced to Central America by humans.
24% of golden-backed squirrel monkeys have tested positive for malaria.
Studies of the brain anatomy of black squirrel monkeys showed that the occipital lobe was devoted to auditory processing and was proportionally the most extensive of all primates except humans. This may be the result of the complex vocalization system utilized by squirrel monkeys.
Recent Research with Squirrel Monkeys:
(Note: The following are examples of recent research done with these primates, it is by no means an exhaustive list. This list will be periodically updated as more information becomes available. Also, though Mindy's Memory Primate Sanctuary DOES NOT support invasive medical research on primates, some articles of this type will be listed - both for information purposes and as examples of the work that is currently being done with these animals.)
Abee CR.
Squirrel monkey (Saimiri spp.) research and resources. ILAR J 41:2-9, 2000.
Biben M
Squirrel monkey playfighting: Making the case for a cognitive training function for play. Pp. 161-182 in ANIMAL PLAY: EVOLUTIONARY, COMPARATIVE, AND ECOLOGICAL PERSPECTIVES. Bekoff M, ed. Cambridge, Cambridge Univ Press, 1998.
Boinski S
The social organizations of squirrel monkeys: Implications for ecological models of social evolution. EVOLUTIONARY ANTHROPOLOGY 8(3): 101-112, 1999.
Boinski S; Cropp SJ
Disparate data sets resolve squirrel monkey (Saimiri) taxonomy: Implications for behavioral ecology and biomedical usage. INTERNATIONAL JOURNAL OF PRIMATOLOGY 20(2): 237-256, 1999.
Boinski, S; Sirot, L
Uncertain conservation status of squirrel monkeys in Costa Rica, Saimiri oerstedi oerstedi and Saimiri oerstedi citrinellus. FOLIA PRIMATOLOGICA 68(3-5): 181-193, 1997.
Brady AG
Research techniques for the squirrel monkey (Saimiri sp.). ILAR [INST LAB ANIM RESOUR] JOURNAL 41(1): 10-18, 2000.
Galland GG.
Role of the squirrel monkey in parasitic disease research. ILAR J 41:37-43, 2000.
Gibson S; Williams L; Brady A and Abee C.
Failure to thrive syndrome in squirrel monkey infants (Saimiri spp.). AMERICAN JOURNAL OF PRIMATOLOGY 45(2): 181-182, 1998.
Johnson EH; Chima SC; Muirhead DE
A cerebral primitive neuroectodermal tumor in a squirrel monkey (Saimiri sciureus). JOURNAL OF MEDICAL PRIMATOLOGY 28(2): 91-96, 1999.
Jung JU; Choi JK; Ensser A; Biesinger B
Herpesvirus saimiri as a model for gammaherpesvirus oncogenesis. SEMINARS IN CANCER BIOLOGY 9(3): 231-239, 1999.
Kinzey, W G
Synopsis of New World primates: Saimiri. Pp. 297-305 in NEW WORLD PRIMATES: ECOLOGY, EVOLUTION, AND BEHAVIOR. W.G. Kinzey, ed. New York, Aldine de Gruyter, 1997.
Lyons DM; Wang OJ; Lindley SE; Levine S; Kalin NH and Schatzberg AF.
Separation induced changes in squirrel monkey hypothalamic-pituitary-adrenal physiology resemble aspects of hypercortisolism in humans. PSYCHONEUROENDOCRINOLOGY 24(2): 131-142, 1999.
Mackic, J B; Weiss, M H; Miao, W; Kirkman, E; Ghiso, J; Calero, M; Bading, J; Frangione, B; Zlokovic, B V
Cerebrovascular accumulation and increased blood-brain barrier permeability to circulating Alzheimer's amyloid beta peptide in aged squirrel monkey with cerebral amyloid angiopathy. JOURNAL OF NEUROCHEMISTRY 70(1): 210-215, 1998.
McClure H; Amin M; Anderson D; Keene TE; et al
Spontaneous prostate cancer in a squirrel monkey. JOURNAL OF UROLOGY 161(4, ann mtg): 128, 1999. (Abstract)
Robinson EL; Fuller CA
Light masking of circadian rhythms of heat production, heat loss, and body temperature in squirrel monkeys. AMERICAN JOURNAL OF PHYSIOLOGY 276(2, pt 2): R298-R307, 1999.
Rogers, K.
Santa Barbara Zoo announces squirrel monkey birth. AZA COMMUNIQUE (Jan): 18, 1999.
Rosenblum LA, Coe CL, editors.
1985. Handbook of Squirrel Monkey Research. New York: Plenum Press. Rosenblum LA, Cooper RW, editors. 1968. The Squirrel Monkey. New York: Academic Press.
Scammell JG. Steroid resistance in the squirrel monkey: An old subject revisited. ILAR J 41:19-25. Williams L, Glasgow M. 2000. Squirrel monkey behavior in research. ILAR J 41:26-36, 2000.
Schreiber A; Wang M; Kaumanns W
Captive breeding of squirrel monkeys, Saimiri sciureus and Saimiri boliviensis: The problem of hybrid groups. ZOO BIOLOGY 17(2): 95-109, 1998.
References:
Rowe N (1996) The Pictorial Guide to the Living Primates. East Hampton: Pogonias Press
Sleeper B (1997) Primates. San Francisco: Chronicle Books
