Genus Saimiri

Diurnal and primarily arboreal, squirrel monkeys form large multimale–multifemale troops that travel, forage, and rest together; group size varies from a few dozen to several hundred in some populations. They use an extensive vocal repertoire, scent marking and rapid visual displays for communication, show coordinated foraging strategies, and employ alarm calls or mobbing to deter predators.

Reproduction is generally seasonal and timed to local rainfall/fruiting cycles; estrus and peak births often coincide with periods of high food availability. Gestation is about 150 days (≈5 months), typically producing a single infant (twins are uncommon); mothers provide primary care while other group members may aid in protection and tolerance of juveniles.

Adults are small (body length ~25–35 cm; weight ~0.5–1.1 kg), with long tails used for balance but not prehension. Coat coloration is usually olive or gray dorsally with yellowish limbs and a white facial mask; they have high metabolic rates, sharp vision, nimble hands, and dental adaptations for an omnivorous diet of fruit, insects and small vertebrates.

Native to Central and South American forests and gallery woodlands, squirrel monkeys have long been common components of Neotropical primate communities. They were historically collected for the pet trade and used extensively in biomedical research and as laboratory animals, which influenced both scientific knowledge and exploitation pressures.

Conservation status varies by species and region—some Saimiri taxa are listed as Least Concern while localized populations face declines from habitat loss, fragmentation, hunting and capture for trade. Conservation actions include habitat protection, regulated trade, population monitoring, and education; maintaining large, connected forest tracts is critical for sustaining natural social groups and gene flow.