Saimiri oerstedii

Geographic Distribution and Habitat

Black crowned Central American squirrel monkeys (Saimiri oerstedii), also known as Central American squirrel monkeys and red-backed squirrel monkeys, are endemic to the Pacific coast of Costa Rica and inland Panama. Two subspecies occur along the Pacific coast of Costa Rica: S. o. oerstedii, also commonly called black-crested Central American squirrel monkeys, and S. o. citrinellus, commonly called gray-crowned Central American squirrel monkeys. They are differentiated by their geographic locations.

Black crowned Central American squirrel monkeys prefer seasonally inundated forests, river edge forest, floodplain, and secondary forests and use all levels of the forest, but forage and travel mainly in the lower canopy and understory.

Central American Squirrel monkey range, IUCN 2020
Size, Weight, and Lifespan

Male and female squirrel monkeys are similar in size and typically measure 8.8 to 11.6 inches (22.3–29.4 cm). Their tails add an additional 14–18 inches (35.5–45.7 cm). On average, females weigh 1.53 pounds (695 g) and males weigh 1.82 pounds (829 g).

Squirrel monkeys can live up to 20 years in the wild.


Black crowned Central American squirrel monkeys are small and slender with long tails. Much of their body pelage, as well as their hands, feet, and forearms, are a yellow-brown color. Their bellies are pale yellow. Just as their alternate common name—the red-backed squirrel monkey—indicates, they have golden-red colored hair on their backs. The hips and shoulders are grayish-brown as are their tails, which are tipped with black.

Black crowned Central American squirrel monkeys can be distinguished from Guianan squirrel monkeys by the crown atop their heads. Black crowned Central American squirrel monkeys’ crown is covered in black hair while Guianan squirrel monkeys have brownish-gray crowns.


Like most squirrel monkeys, black crowned Central American squirrel monkeys are frugivore-insectivores. Their diet consists of fruit, seeds, flowers, invertebrates, and small vertebrates. They spend 75-80% of their day foraging for insects and other small animal prey. During dry season shortages of appropriate fruiting trees, they are able to depend entirely on animal prey. They have been known to attack leaf-tents, where fruit-eating bats rest, to extract the bats. Most of their prey, however, are invertebrates.

Behavior and Lifestyle

Black crowned Central American squirrel monkeys are arboreal (tree-dwelling) and diurnal (active during daylight hours); they are most active in morning and late afternoon. Groups forage shortly after sunrise and about an hour after sunset. They travel quadrupedally (on all fours) along tree branches and use their tail (which is non-prehensile, and therefore cannot grasp objects) for balance.

These monkeys are excellent leapers and grippers. The hands and feet of squirrel monkeys are exceptionally dexterous, allowing them to make quick maneuvers through the trees without slipping. Sometimes when feeding, they sit in an upright position on branches holding their food in their hand(s). Their long tails are used for balance so they don’t accidentally topple off the branch.

Fun Facts

Central American squirrel monkeys spend the majority of their life in the middle and high canopy layer in the forest.

Squirrel monkeys have excellent eyesight and they are able to distinguish colors. This allows them to identify fruit among dense vegetation.

As a result of increased agriculture and shrinking of the territory of squirrel monkeys, they frequently invade plantations. 

Daily Life and Group Dynamics 

Generally speaking, squirrel monkey troops can be quite large, consisting of as many as 300 individuals. The larger-sized troops occur when two or more smaller groups temporarily merge, whether for feeding, mating, or protection. Each of the smaller groups within the troop can be as large as 100 individuals, but most range between 20-75 individuals. Each group is compromised of multiple males and multiple females.

Although all squirrel monkeys are morphologically very similar, their social systems are quite distinct. Among black crowned Central American squirrel monkeys, females do not form dominance hierarchies, and there is no evidence of coalition formation in social interactions. Females transfer between groups before their first mating season, and males are philopatric, that is, they remain with the natal group.

There is little competition or agonistic interactions between groups, and males show high levels of vigilance for protecting the group against predators. The fruits they typically exploit occur in small and very scarce patches, and feeding competition is very low.

Most squirrel monkey species are very sociable monkeys. They begin playful activities around two months of age. Social play helps the infants become independent from the mother. Throughout the first year of life, young monkeys play with each other, often in the form of fighting games.


Squirrel monkeys use complex communication behaviors such as distinct vocalizations, postural displays, and olfactory cues. They have at least 25 to 30 calls that consist of peeps, chucks, twitters, and cackles.

Most of the time, peeps are used when playing, when exploring, or when frustrated. During feeding, isolation and greeting twitters are common vocalizations. These are tonal and differ based on the individual caller; on the other hand, peeps are tonal vocalizations that tend not to differ based on the individual caller.

Chucks are used the most among squirrel monkeys and are frequently heard between mother-infant interactions, sexual behavior, and alarm calls. Cackles are low in frequency and are often heard during disturbances or agonistic encounters.

The most widely used postural displays in squirrel monkeys is also a method of olfactory communication. Urine-washing is used when a male or female urinates on their hands and feet then spreads the urine over their own body. Sometimes urine-washing includes marking trails for other group members, displays of dominance, or even controlling body temperature.

Reproduction and Family

Females become sexually mature at around one year of age, while males reach maturity around their fourth or sixth year. 

Mating and births in squirrel monkeys are highly seasonal, seldom exceeding two months in duration. Reproductively mature males collaborate in mobbing females during the mating season. Mating usually occurs during the wet season, with births typically in February. A single infant is born after a 7-month gestation period. Interbirth intervals are about 12 months. 

The monkey infant rides on his or her mother’s back and nurses for the first few weeks of his or her life. Between the fifth and tenth week, he or she occasionally leaves the mother’s back to explore nearby areas. The youngster will start to eat solid food during this time. After a few months, contact with the mother become less frequent. In general the mother cares for her young, though sometimes other females help—they are referred to as “aunts.”

Ecological Role

One can assume, because of their diet, that Central American squirrel monkeys play a role in dispersing and excreting seeds from fruits and flower buds throughout the forest while traveling.

Conservation Status and Threats

The black crowned Central American squirrel monkey is listed as Endangered by the International Union for Conservation of Nature, appearing on the IUCN’s Red List of Threatened species (IUCN, 2020). Their populations have declined by about 60% over the last 27.5 years and their range is severely fragmented range and there is ongoing loss of habitat.

The major threat across their range is habitat loss, primarily due to agriculture and logging.

In Panama, specific threats include deforestation for farming, cattle ranching, teak plantations, palm oil plantations, urban investments, hydroelectric and other industrial activities. Other threats are the use of herbicides and live capture for the pet trade.

In Costa Rica, there are six main threats to the conservation of squirrel monkeys besides forest fragmentation and habitat loss:

  • Squirrel monkeys are tormented and killed as crop-raiding pests
  • Palm oil and teak plantations fragment the squirrel monkeys’ habitats, preventing the monkeys from connecting to other areas
  • Rescue centers are reporting new squirrel monkey arrivals, especially during the birth season, from monkeys captured for the pet trade
  • There are areas where squirrel monkeys are found dead from electrocution due to contact with electrical wires
  • There are also new threats as road kills, mainly in the Central Pacific but also occurring in Southern Costa Rica, along with habitat fragmentation and habitat loss.
  • Some dead squirrel monkeys were reported attacked and dead by hunting dogs and, less commonly, by domestic dogs

Conservation Efforts

Central American squirrel monkeys are listed on the Convention on International Trade in Endangered Species (CITES) Appendix I and occur in numerous protected areas in Costa Rica and Panama.


  • ​Boinski, S. et al. 1998. Squirrel monkeys in Costa Rica: drifting to extinction. Oryx 32:45.

Written by Tara Covert, January 2020. Conservation status updated April 2021.