Guianan Squirrel Monkey (Saimiri sciureus) Fact Sheet: Summary

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia — mammals

Order: Primates — primates

Family: Cebidae — New World monkeys

Genus: Saimiri — squirrel monkeys

Species: Saimiri sciureus* — Guianan squirrel monkey, South American squirrel monkey, common squirrel monkey

*Note: Saimiri sciureus and S. collinsi now considered separate species (Lynch Alfaro et al. 2015; Mercês et al. 2015).

Synonyms

Chrysothrix nigrivittata, Lemur leucopsis, Saimiri sciureus sciureus, Sapajou saimiri, Simia apedia, Simia morta, Simia sciurea

Sources: Hershkovitz (1984), Rylands and Mittermeier (2013), ITIS (2022), Silva Júnior et al. (2022)

Body Weight

Male: 779–911 g (1.72–2.01 lb) (Feagle 2013)
Female: 668–711 g (1.47–1.57 lb) (Feagle 2013)

Note: Rylands and Mittermeier (2013) give a wider weight range: males, 550–1,400 g (1.2–3.1 lb); females: 550–1,200 g (1.2–2.6 lb).

Head-body Length

Male: 25–37 cm (9.8–15 in)
Female: 25–34 cm (9.8–13 in)

(Rylands and Mittermeier 2013)

Tail Length

Male: 36–40 cm (14–16 in)
Female: 36–47 cm (14–19 in)

(Rylands and Mittermeier 2013)

General Appearance

Small body with long limbs for arboreal life. Hind limbs longer than forelimbs. Head round and elongate, with large, closely spaced eyes. Fur short, dense, and richly colored. Ears and tail with long tufts (Husson 1978; Fleagle 2013).

Coloration

Generally grayish or greenish to reddish, with agouti “pepper and salt” coloring on head crown. Eyes bordered by white and pink. Muzzle black. Ear tufts white. Last third of tail black; remainder is gray. Body buff-colored with yellow–orange forearms, legs, and feet. Underside white (e.g., Husson 1978; Rylands and Mittermeier 2013). Coloration of adults and infants similar (Baldwin and Baldwin 1981).

Range

Northern South America, including Guyana, Suriname, French Guiana, and northern Brazil (Silva Júnior et al. 2021).

Habitat

Adapted to wet and dry forests. Subtropical and tropical lowland forest, including rainforest, seasonally inundated forest, and gallery forest. Generally show a preference for habitat areas near rivers (Husson 1978; Fleagle 2013). Also occur in mangroves. Some ability to adapt to disturbed forest (Baldwin and Baldwin 1981; Rylands and Mittermeier 2013; Silva Júnior et al. 2021).

Prefer mid-forest levels, but also use forest floor and canopy (Husson 1978).

IUCN Status

Least Concern. Population trend: decreasing (Silva Júnior et al. 2021).

CITES Appendix

Appendix II (UNEP 2022)

Populations in the Wild

No estimates reported. Considered widespread and common within its range. Found within many protected areas (Rylands and Mittermeier 2013).

Threats to Survival

No major threats. Generally not hunted due to their small size (Rylands and Mittermeier 2013; Henfrey 2020; Silva Júnior et al. 2021). Infrequently taken by subsistence hunters (e.g., Shaffer et al. 2017).

Previously captured for the pet trade and biomedical research (imports to the U.S. ceased in the mid-1970s) (Rosenblum and Cooper 1968; Dukelow 1983; Abee 1989; Rylands and Mittermeier 2013; Rylands et al. 2013).

Other squirrel monkeys threatened by deforestation, habitat fragmentation, and the pet trade (Rylands et al. 2013).

Activity Patterns

Diurnal; very active during the day (Du Mond 1968; Husson 1978; Baldwin and Baldwin 1981; Eisenberg 1989; Stone 2004). Rest during hottest time of the day (Thorington 1968). Less active during heavy rain (Du Mond 1968; Baldwin and Baldwin 1981).

Spend up to half their time foraging and eating, with additional time spent during the dry season (Stone 2007). Travel time also significant. Smaller amounts of time spent resting and engaging in social behavior (Rylands and Mittermeier 2013).

Home Range

Typically 100–123 ha (200–303 acres) (Rylands and Mittermeier 2013). Ranges of different groups overlap extensively (Eisenberg 1989).

Movements and Dispersal

Travel about 2,300 m (1.4 mi) per day (Rylands and Mittermeier 2013).

Females disperse as adults, while males stay near their place of birth. Both sexes undertake dispersal between groups during their lifetimes (Kauffman et al. 2005).

Social Behavior

Mixed male-and-female groups typically containing 25 to 75 members (Boinski 1999). Group size can be fewer than 20 individuals in fragmented forest or more than 100 individuals in areas of continuous forest (Pinheiro et al. 2013).

Females and juveniles form core of social groups, with males remaining near group’s periphery for most of the year (average sex ratio: 4 females to 1 male). In larger groups, mother–infants and members of same age class tend to interact most frequently. Females form stable social ties without hierarchy (unless under conditions of stress). Males compete for dominance, though access to food and mates depends on a combination of factors (Ploog et al. 1963; Ploog 1967; Baldwin 1971; Castell and Heinrich 1971; Baldwin and Baldwin 1981; Stone 2004; Izar et al. 2009). In some locations, frequently fight over fruit (Baldwin 1971; Baldwin and Baldwin 1981; Eisenberg 1989; Rylands and Mittermeier 2013).

Communication

Many vocalizations given — e.g., to make contact with group members, during feeding, when showing aggression, and as predator-detection calls (Winter et al. 1966; Ploog 1967; Du Mond 1968; Thorington 1968; Winter 1968; Eisenberg 1989; Rylands et al. 2013).

Visually signal through postures, movements, facial expressions, and stereotyped displays — e.g., genital displays used to signal social status (Ploog et al. 1963; Ploog 1967; Baldwin and Baldwin 1981; Vermeer 2006).

Olfactory communication includes gland secretions, urine, and body odor (Kaplan and Russell 1974; Baldwin and Baldwin 1981; Rylands et al. 2013).

Interspecies Interactions

Saimiri form mixed-species groups, particularly with Cebus monkeys (Baldwin and Baldwin 1971; Klein and Klein 1973), likely to benefit from capuchins’ predator-detection ability (Terborgh 1983; Jack 2011).

Young squirrel monkeys associate with marmosets and uakaris during play (Du Mond 1968).

Other Behaviors

Sleep on top of branches, squatting with head down, and tail curled over a shoulder or between legs (conserves body heat). Infants, juveniles, and male subadults play socially (jumping, chasing, tackling, tumbling, wrestling) and with objects (bark, leaves) (Ploog et al. 1967; Baldwin and Baldwin 1981).

Scratching can suggest anxiety, e.g., after fights with group members (Rylands et al. 2013).

Diet and Feeding

Insects (e.g., flies, caterpillars, grasshoppers), particularly during the dry season, and fruits, especially small, sweet, berry-like fruits. Also, flowers, nectar, seeds, gums, spiders, lizards, and bird eggs. Similar diet to Collins’ squirrel monkey (Saimiri sciureus and S. collinsi formerly considered one species) (Thorington 1968; Husson 1978; Stone 2004, 2007; Rylands and Mittermeier 2013; Rylands et al. 2013).

Inspect and unroll leaves to find hiding insects (Baldwin and Baldwin 1981; Janson and Boinski 1992). Forage in leaf litter for insects during dry season. Higher fruit consumption during wet season (Stone 2004, 2007). Abundant palm tree fruits allow for group feeding (Stone 2007; Rylands and Mittermeier 2013).

Drink from tree holes or on the ground, but most water absorbed from food (Baldwin 1967, cited by Baldwin and Baldwin 1981).

Predators

Raptors (hawks, eagles) (Terborgh 1983; Fleagle 2013; Duarte and Carvalho 2019)
Boas (Ribeiro-Júnior et al. 2016)

Locomotion

Run, climb, and leap among branches using hands and feet together. Adults jump up to 5 m (15 ft); extend arms and legs forward and land with all 4 limbs. Climb up vertically using limbs on one side together, or ‘hopping’ while pulling with arms. Pounce on insect food (e.g., flies, butterflies). Tail used for balance (Husson 1978; Baldwin and Baldwin 1981; McNamara et al. 2019).

Relationship with Humans

High degree of coexistence (Lima et al. 2021). Also see Threats to Survival.

Breeding

Seasonal, synchronous breeding and birthing periods. Mating period lasts about 9 weeks in the early dry season (e.g., Zimbler-DeLorenzo and Stone 2011). Promiscuous mating system. Males associate more closely with female groups (Du Mond and Hutchinson 1967; Baldwin 1968; Baldwin and Baldwin 1971; Coe and Rosenblum 1978; Trevino 2007; Izar et al. 2009) and develop secondary breeding characteristics, such as a thicker fat layer below the skin, appearance of thicker fur (“fatted condition”), and more vocalizing and aggressive behavior (Du Mond and Hutchinson 1967; Du Mond 1968; Stone 2014).

Maternal Care

Births among group members all occur within a week of one another (early wet season). Infants carried and cared for by their mother, and often younger females or females that lost an infant (Baldwin and Baldwin 1981; Rylands and Mittermeier 2013; Rylands et al. 2013). Young begin exploring on their own at about 4–7 weeks; independent at about 11 months old (Baldwin 1969; Baldwin and Baldwin 1981; Stone 2004).

Sexual Maturity

Males: full maturity at 4–5 years
Females: mature at 2.5 years; first young born at 3.5 years

(Baldwin and Baldwin 1981; Rylands and Mittermeier 2013)

Gestation

About 5 months (Beischer and Furry 1964; Eisenberg 1989; Rylands and Mittermeier 2013)

Litter Size

1 infant (Goss et al. 1968; Baldwin and Baldwin 1971)

Interbirth Interval

1–2 years (Rylands and Mittermeier 2013)

Birth Weight

80–140 g (3–5 oz) (Baldwin and Baldwin 1981)

Age at Weaning

About 6 months of age; nursing may extend to 8 months (Stone 2004; Rylands and Mittermeier 2013). Stone (2004) states weaning begins as early as 4 months; may need confirmation.

Longevity

In the wild: 20 years or longer (Rylands and Mittermeier 2013)
In managed care: 20–30 years (Weigl 2005; ZIMS 2022)

Feature Facts

• Agile, tree-dwelling primates that move continuously, feeding on insects and ripening fruit (Husson 1978; Baldwin and Baldwin 1981; Fleagle 2013)
• Closely related to capuchin monkeys, though much smaller (Jack 2011; Rylands et al. 2013)
• Tail not prehensile as adults but used for balance, staying warm, and possibly tactile communication (Husson 1978; Jack 2011)
• Males and females rub urine on their palms and the soles of their feet, possibly to communicate reproductive status, improve thermoregulation, or other benefit (e.g., Thorington 1968; Vermeer 2006; Zimbler-DeLorenzo and Stone 2011)
• Male dominance behaviors include grasping of another monkey’s head or torso, tail pulling, and biting, in addition to genital displays (e.g., Alvarez 1975; Vermeer 2006)
• Lay across branches in hot weather (Du Mond 1968)
• Saimiri sent on early space flights in aerospace medical research (Rosenblum and Cooper 1968; Rylands et al. 2013)