|Scientific Name:||Saimiri ustus I. Geoffroy, 1843|
|Taxonomic Notes:||Saimiri taxonomy follows Hershkovitz (1984) and Groves (2001, 2005). An alternative taxonomy is presented by Thorington Jr. (1985) as follows: S. sciureus sciureus (includes the forms albigena, macrodon, and ustus recognized by Hershkovitz, ), S. sciureus boliviensis (includes the forms pluvialis Lönnberg, 1940 and jaburuensis Lönnberg, 1940 recognized by Hershkovitz ), S. sciureus cassiquiarensis, S. sciureus oerstedii (includes the form citrinellus recognized by Hershkovitz ), and S. madeirae (given as a junior synonym of S. ustus by Hershkovitz ). Hernández-Camacho and Defler (1989) recognize S. sciureus caquetensis Allen 1916, given as a junior synonym of S. sciureus macrodon by Hershkovitz (1984). Costello et al. (1993) argued for the recognition of just two species: S. sciureus in South America, and S. oerstedii in Panama and Costa Rica. Boinski and Cropp (1999) using two nuclear genes (IRBP and ZFX) and one mitochondrial (D-Loop) strongly support the Hershkovitz (1984) taxonomy, advocating four distinct species: Saimiri sciureus, S. boliviensis, S. oerstedii and S. ustus.|
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Assessor(s):||de Oliveira, M.M. de & Boubli, J.-P.|
|Reviewer(s):||Mittermeier, R.A. & Rylands, A.B. (Primate Red List Authority)|
Listed as Near Threatened as past and predicted future declines in the species' population are estimated to be in the region of 20-25% over a 25-year period (three generations) mainly due to the rapid loss of habitat in the southern portion of its range, and the high probability of increased habitat loss in the future due to flooding from hydroelectric projects, highway construction, logging and clear-cutting, and industrialized agriculture (soya and, in the future, biofuel crops). Almost qualifies as threatened under criterion A4c.
|Previously published Red List assessments:|
|Range Description:||Saimiri ustus occurs south of the Rio Amazonas in Brazil. It has more restricted range than was supposed by Hershkovitz (1984), who placed it east of the Rio Purus south as far as the region of the rios Sepatini and Guaporé, east to the Rios Xingu or Iriri. J. S. Silva Jr. (pers. comm.) believes it extends east of the Rio Purus to the riosTapajós and Juruena, with its range including a belt along the southern margin of the Rio Solimões along the lower reaches of the southern tributaries, including the rios Coarí and Tefé to the east (left bank) of the Rio Juruá. It extends south to the upper reaches of the Rio Guaporé and the headwaters of the Juruena. It is replaced by Saimiri sciureus sciureus just south of the Rio Amazonas, east of the Tapajós, on the Ilha Tupinambarama, east to Parintins.|
Native:Brazil (Amazonas, Mato Grosso, Pará, Rondônia)
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||There are no published density estimates available.|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||Typically prefers seasonally inundated forests, river edge forest, floodplain, and secondary forests. They use all levels of the forest, but forage and travel mainly in the lower canopy and understorey. Locomotion involves predominantly quadupredal walking and running.|
Squirrel monkeys are small frugivore-insectivores. They spend 75-80% of their day foraging for insects and other small animal prey (Mittermeier and Van Roosmalen 1981; Terborgh 1983; Boinski 1988). During dry season shortages of appropriate fruiting trees they are able to depend entirely on animal prey (Janson and Boinski 1992).
Saimiri groups are multi-male and can be large, up to 100 animals (larger groups are believed to be temporary mergers of two) but most frequently are of 20-75 individuals (Baldwin and Baldwin 1981; Terborgh 1983; Mitchell et al. 1991). As emphasized by Boinski (1999a,b; 2005; Boinski et al. 2005a,b) allthough all squirrel monkeys are morphologicallly very similar, their social systems are quite distinct (summarized in Sussman 2000). There have been no studies of this species, however, and its ecology is inferred from those of other species.
Mating and births in Saimiri are highly seasonal, seldom exceeding two months in duration. Single offspring. Mating usually occurs during the dry season. In S. oerstedii, sexual receptivity in females is synchronized, and lasts only or two days each season. In S. sciureus, birth synchrony is less pronounced and births occur only once every two years.
Amazonian Saimiri frequently form interspecific associations, travelling with Cebus albifrons or Cebus apella (Terborgh 1983; Wallace et al. 2000), benefitting from the disturbance casued by the capuchin monkeys above them which flushes out insects.
Adult male 620-1,200 g (mean 910 g); adult female 710-880 g (mean 795 g) (Jack 2007).
Although the species is wide ranging, much of its range in northern Mato Grosso and southern Para is undergoing massive deforestation along the so-called arc of deforestation (the advancing agricultural frontier of logging, cattle, and soy bean).
In the Rio Madeira region, there are several hydroelectric projects that are likely to inundate flooded forests, this species' preferred habitat. Also, in the past 15 years there has been intensive habitat loss in the southern third of this species range due to agriculture and logging activities.
This species occurs in a number of protected areas, including:
Amazônia National Park (1,114,917 ha)
Pacaás Novos National Park (764,801 ha)
Juruena National Park
Jarú Biological Reserve (353,386 ha)
Guaporé Biological Reserve (618,173 ha)
Iquê Ecological Station (217,184 ha)
It is listed on CITES Appendix II.
Baldwin, J. D. and Baldwin, J. I. 1981. The squirrel monkeys, genus Saimiri. In: A. F. Coimbra-Filho and R. A. Mittermeier (eds), The Ecology and Behavior of Neotropical Primates, pp. 277-330. Academia Brasileira de Ciências, Rio de Janiero, Brazil.
Boinski, S. 1988. Sex differences in the foraging behavior of squirrel monkeys in a seasonal habitat. Behavioural Ecology and Sociobiology 23: 177-186.
Boinski, S. 1999. Geographic variation in behavior of a primate taxon: stress responses as a proximate mechanism in the evolution of social behavior. In: S. A. Foster and J. A. Endler (eds), Geographic Variation in Behavior: Perspectives om Evolutionary Mechanisms, pp. 95-120. Oxford University Press, Oxford, UK.
Boinski, S. 1999. The social organization of the squirrel monkeys: implications for ecological models of social evolution. Evolutionary Anthropology 8: 101-112.
Boinski, S. and Cropp, S. J. 1999. Disparate data sets resolve squirrel monkey (Saimiri) taxonomy: Implications for behavioral ecology and biomedical usage. International Journal of Primatology 20(2): 237–256.
Boinski, S., Ehmke, E., Kauffman, L., Schet, S. and Vreedzaam, A. 2005. Dispersal patterns among three species of squirrel monkeys (Saimiri oerstedii, S. boliviensis and S. sciureus): II. Within-species and local variation. Behaviour 142(5): 633-677.
Boinski, S., Kauffman, L., Ehmke, E., Schet, S. and Vreedzaam, A. 2005a. Dispersal patterns among three species of squirrel monkeys (Saimiri oerstedii, S. boliviensis and S. sciureus): I. Divergent costs and benefits. Behaviour 142(5): 525-632.
Costello, R. K., Dickinson, C., Rosenberger, A. L., Boinski, S. and Szalay, F. S. 1993. Squirrel monkey (genus Saimiri) taxonomy: a multidisciplinary study of the biology of the species. Plenum Press, New York, USA.
Groves C. 2001. Primate Taxonomy. Smithsonian Institution Press, Washington, DC, USA.
Groves, C.P. 2005. Order Primates. In: D.E. Wilson and D.M. Reeder (eds), Mammal Species of the World, pp. 111-184. The Johns Hopkins University Press, Baltimore, Maryland, USA.
Hernández-Camacho, J. and Defler, T. R. 1989. Algunos aspectos de la conservación de primates no-humanos en Colombia. In: C. J. Saavedra, R. A. Mittermeier and I. B. Santos (eds), La Primatología en Latinoamerica, pp. 67-100. WWF-U.S., Washington, DC, USA.
Hershkovitz, P. 1984. Taxonomy of squirrel monkeys, genus Saimiri, (Cebidae, Platyrrhini): a preliminary report with description of a hitherto unnamed form. American Journal of Primatology 4: 209–243.
Hershkovitz, P. 1987. Uacaries, New World monkeys of the genus Cacajao (Cebidae, Platyrrhini): a preliminary taxonomic review with the description of a new subspecies. American Journal of primatology 12: 1–53.
Jack, K. 2007. The cebines: toward an explanation of variable social structure. In: C. J. Campbell, A. Fuentes, K. C. Mackinnon, M. Panger and S. K. Bearder (eds), Primates in Perspective, pp. 107-123. Oxford University Press, Oxford, UK.
Janson, C. H. and Boinski, S. 1992. Morphological and behavioral adaptations for foraging in generalist primates: the case of the Cebines. American Journal of Physical Anthropology 88: 483-498.
Mitchell, C. L., Boinski, S. and Van Schaik, C. P. 1991. Competetive regimes and female bonding in two species of squirrel monkey (Saimiri oerstedi and Saimiri sciureus). Behavioural Ecology and Sociobiology 28: 55-60.
Mittermeier, R. A. and Van Roosmalen, M. G. M. 1981. Preliminary observations on habitat utilization and diet in eight Surinam monkeys. Folia Primatologica 36: 1–39.
Sussman, R. W. 2000. Primate Ecology and Social Structure, Vol. 2: New World Monkeys. Pearson Custom Publishing, Needham Heights, MA, USA.
Terborgh, J. 1983. Five New World Primates: A Study in Comparative Ecology. Princeton University Press, Princeton, NJ, USA.
Thorington Jr., R. W. 1985. The taxonomy and distribution of squirrel monkeys (Saimiri). In: L. A. Rosenblum and C. L. Coe (eds), Handbook of Squirrel Monkey Research, pp. 1–33. Plenum Press, New York, USA.
Wallace, R. B., Painter, R. L. E., Rumiz, D. I. and Taber, A. B. 2000. Primate diversity, distribution and relative abundances in the Rios Blanco y Negro Wildlife Reserve, Santa Cruz Department, Bolivia. Neotropical Primates 8(1): 24–28.
|Citation:||de Oliveira, M.M. de & Boubli, J.-P. 2008. Saimiri ustus. The IUCN Red List of Threatened Species 2008: e.T41538A10494703.Downloaded on 23 September 2017.|
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