Table of Contents
Overview
Distribution
Range Description
Saimiri boliviensis peruviensis occurs south of the Ríos Amazon and Marañón, between the Rios Huallaga and Ucayali, from the west bank of the Río Tapiche (tributary of the Ucayali), south between the Ríos Pachitea and Tambo (Hershkovitz 1984). Hershkovitz (1984) indicated that the southern limits were unknown, but presumed to be at least as far as the Río Abujao (a west bank affluent of the Río Ucayali). Aquino and Encarnación (1994) indicated the region of the Río Perené, a tributary of the Rio Pachitea. Aquino and Encarnación (1994) reported that is sympatric with Saimiri sciureus macrodon east of the Río Ucayali from about 04ºS southward to the Rio Abujao. In their map, S. b. boliviensis extends across the Rio Blanco to the Río Yavarí. Its occurrence in Brazil to the east of the Rio Javarí has not been documented.
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Geographic Range
Saimiri boliviensis, Bolivian squirrel monkeys, can be found in the tropical rain forests of South America. They are found from the Andes in the east, north to the Caribbean Sea, and south and east into Brazil.
Biogeographic Regions: neotropical (Native )
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Physical Description
Morphology
Physical Description
Squirrel monkeys (Saimiri) are all fairly similar in appearance. The head is elongated and egg-shaped (Napier and Napier, 1967). It has been suggested that this characteristic cranial morphology is a compromise between a small facial skeleton and a relatively large braincase (Ankel-Simons, 2000). The fur of Bolivian squirrel monkeys is dense and short, and is generally a yellowish tan color, mottled with black hair tips (Ankel-Simons, 2000). The fur on the undersides of the limbs is yellow, white, or orange (Napier and Napier, 1967). Males and females are very similar in appearance, with sexual dimorphism occurring in size and color of crown fur (gray in males and black in females). The sizes of male Bolivian squirrel monkeys range in length, weight, and tail length, from 250-370mm, 550-1135g, and 370-465mm respectively. Females are smaller than males, from 225-295mm in length, weighing 365-750g, and having tail lengths of 370-445mm (Chiarelli, 1972). The face has white areas on the cheeks and around the eyes that appear “mask-like” (Ankel-Simons, 2000). One key identifying feature of S. boliviensis that differs from other squirrel monkeys is the arched eyebrows (Gibson, Kuehl, and Ruiz, 2005). The snout of S. boliviensis is similar to other squirrel monkeys. It is short and blunt in shape and dark in color. The ears are white and tufted and are large in comparison to the monkey’s head. The tail , which has a black tip, is almost twice the length of the body but is not prehensile. However, the tail is not prehensile. They have pseudoopposable thumbs (Ankel-Simons, 2000).
Range mass: 365 to 1135 g.
Range length: 225 to 370 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; sexes colored or patterned differently
- Chiarelli, A. 1972. Taxonomic Atlas of Living Primates. London: Academic Press.
- Gibson, S., T. Kuehl, J. Ruiz. 2005. "Squirrel Monkey Breeding and Research Resource" (On-line). Accessed November 23, 2005 at http://www.smbrr.org/.
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Ecology
Habitat
Habitat and Ecology
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).
In S. boliviensis, studied by Terborgh (1983) and Mitchell et al. (1991), groups range from 45 to 75 individuals. Females form stable, probably kin-based, coalitions and dominance hierarchy. Females are philopatric (remain in the groups they were born in), while males leave their groups at 4-5 years old, form all-male (bachelor) groups and then disperse into other groups with both sexes. Males are generally unfriendly to each other, and change groups every one or two years. Females commonly show social agression amongst themselves. Adult females are always dominant to males, harass them, and maintain on them on the periphery of the group. Unlike S. oerstedi, males do not show anti-predator vigilance. The fruits they typically exploit occur in large patches of moderate density, and feeding competition is higher than in S. oerstedii, but lower than in S. sciureus.
In S. sciureus, studied in Suriname by Boinski (1999a,b, 2005; Boinski et al. 2005a,b), group sizes range from 15 to 50, and both sexes form a single, linear hiearchy in the group, with most males being dominant to females. Aggression between females is uncommon, but they do not form coalitions. Males form coalitions and can aggressive to each other. Males show vigilance in defense agianst predators. The fruits they exploit typically occur in small but extremely dense patches, and there is considerable feeding competition between group members, much higher than in S. boliviensis.
In S. oerstedii, females do not form dominance hierarchies, and there is no evidence of coalition formation in social interactions. Females transfer between groups before first mating season, and males are philopatric. There is little competition or agonistic interactions between groups, and males show high levels of vigilance for predators. Reproductively mature males collaborate in mobbing females during the mating season. Their fruits they typically exploit occur in small and very scarce patches, and feeding competition is very low.
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 one or two days each season. In S. sciureus, birth synchrony is less pronounced, and the female gives birth occur once a year (Rowe 1996). In S. boliviensis, the interbirth interval is 24 months (Mitchell 1994).
Saimiri boliviensis and S. sciureus frequently form interspecific associations, travelling with Cebus albifrons or Cebus apella (Terborgh 1983; Wallace et al. 2000), benefitting from the disturbance caused by the capuchin monkeys above them, which flushes out insects and small animal prey.
Size:
Weight: Adult male 992 g, adult female more than 751 g.
Systems
- Terrestrial
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Habitat
Bolivian squirrel monkeys are most commonly found in gallery forests, but will also inhabit forest edges (Ankel-Simons, 2000). Within these tropical rain forests, Saimiri boliviensis are typically arboreal, residing in the canopy among the small branches. However, they will occasionally leave the canopy to the shrub layer or the forest floor to scavenge (Napier and Napier, 1967; Nowak, 2000). They occur at elevations from sea level to 1500 meters (Napier and Napier, 1967).
Range elevation: Sea Level to 1500 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: rainforest
Other Habitat Features: riparian
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Trophic Strategy
Food Habits
The diet of S. boliviensis consists primarily of insects and fruits. Other foods eaten include berries, nuts, flowers, seeds, leaves, arachnids, and small vertebrates such as bats, birds, and eggs (Ankel-Simons, 2000).
Saimiri boliviensis prefers to forage on terminal branches. Often, they will forage in large groups, possibly enhancing their ability to disturb insects and increase capture rates (Rodman and Cant, 1984).
Animal Foods: birds; mammals; amphibians; reptiles; eggs; insects; terrestrial non-insect arthropods; mollusks
Plant Foods: leaves; seeds, grains, and nuts; fruit; flowers; sap or other plant fluids
Primary Diet: omnivore
- Rodman, P., J. Cant. 1984. Adaptations for Foraging in Nonhuman Primates: Contributions to an Organismal Biology of Prosimians, Monkeys, and Apes. New York: Columbia University Press.
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Associations
Ecosystem Roles
Having a primary diet of insects and fruits, S. boliviensis would play several important roles in the ecosystem. First, by eating insects, the insect population is kept in check. Second, by consuming fruit, Bolivian squirrel monkeys act as an agent for seed dispersal. Many seeds cannot germinate or disperse properly without the help of animal digestion.
Ecosystem Impact: disperses seeds
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Predation
Predators of S. boliviensis include harpy eagles (Harpia harpyja) and humans. Eagles are avoided by staying in large groups and remaining vigilant.
Known Predators:
- harpy eagles (Harpia harpyja)
- humans (Homo sapiens)
- 2005. "Rainforest Alliance" (On-line). Accessed November 23, 2005 at http://www.rainforest-alliance.org/resources/forest-facts/species-profiles/squirrelmonkey.html.
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Life History and Behavior
Behavior
Communication and Perception
Saimiri boliviensis is one of the most vocal squirrel monkeys. There are 26 identifiable calls, consisting of chirps and peeps (used when alarmed), squawks and purrs (used during mating and birthing seasons), barks of aggression, and screams of pain (Nowak, 2000). Bolivian squirrel monkeys also communicates with other individuals using chemical signaling. Examples of this include urine-washing (Nowak, 2000) and release of sexual pheromones by females during mating season (Ankel-Simons, 2000). Concerning perception, S. boliviensis has been shown to be polymorphic for cone pigment and color vision, meaning that, like humans, they can see in color (Ankel-Simons, 2000).
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: pheromones
Perception Channels: visual ; acoustic
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Life Expectancy
Lifespan/Longevity
Bolivian squirrel monkeys have lived up to 30 years in captivity.
Range lifespan
Status: captivity: 30 (high) years.
Typical lifespan
Status: captivity: 15 to 20 years.
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Lifespan, longevity, and ageing
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Reproduction
Reproduction
Within a troop of Bolivian squirrel monkeys, mature males live in a subgroup, generally separate from a female/young subgroup (Hinde, 1983). This level of segregation between males and females is unique among Bolivian squirrel monkeys. Theories as to what causes this separation include social dynamics between the males, and female initiated active exclusion (Gibson,Kuehl, and Ruiz, 2005). During the mating season, males, who have a well-developed dominance hierarchy, will interact and mate with the females. The dominance hierarchy in males is based on testosterone levels and copulatory frequency (Gibson,Kuehl, and Ruiz, 2005) as well as fierce fighting (Nowak, 2000). Among males, the more dominant male is allowed to interact with the females. Females will often mate with several males during their short mating season. When a male wishes to mate with a female, he will use an aggressive behavior while making his penis erect. This behavior is also used when approaching an inferior male (Bourne, 1971). When the female becomes submissive, the male mounts her from behind. This mounting behavior has been observed in infants and juveniles who apparently develop the behavior without penetration before maturity (Schrier, 1977). During mating season, males have been known to gain considerable amounts of weight. This "fattening" helps the males by increasing their sperm production. Saimiri boliviensis are polygynandrous creatures, meaning that both males and females in the troop may mate with multiple partners in a given breeding season. Males that do mate with multiple mates are usually the more dominant males (Ruiz et al., 2005). Following the mating season, males and females once again segregate into different groups (Hinde, 1983). Squirrel monkeys also display cooperative breeding behavior, meaning that the mother has help from other females in raising her young (Carpenter, 1973).
Also called “aunting”, cooperative breeding is where helpers provide help in raising young that is not their own. In Bolivian squirrel monkey troops, females will act as “aunts” to the infant of another female. Aunting behavior includes dorsal carriage (carrying the infant on their back), retrieval, and cleaning. “Aunts” can be any female in the group but primarily consist of females who the mother spent a lot of time with prior to birthing, females who the mother previously acted as an “aunt” to, or previously birthed females. As many as nine different subjects have been observed interacting with a given infant in the first week of life. This “aunting” behavior is unique to squirrel monkeys and is thought to create, maintain, and extend group cohesiveness over long periods of time (Carpenter, 1973).
Mating System: polygynandrous (promiscuous) ; cooperative breeder
The breeding season for S. boliviensis is restricted to three months in length with estrus times averaging 7-8 days in length (Gibson,Kuehl, and Ruiz, 2005). Unique among squirrel monkeys is their highly synchronized mating seasons, where every female will come into estrus at approximately the same time. Heavy scent marking by females during the mating season may result in this level of synchronisity. The coordination of fertility among females of the troop may be influenced by these sexual pheromones (Ankel-Simons, 2000). In each breeding season a female will have one offspring (Gibson,Kuehl, and Ruiz, 2005). The gestation period is between 152 and 172 days and weaning occurs between four and six months old (Napier and Napier, 1967). Females reach sexual maturity generally around two and a half to three years of age. Males, on the other hand, will usually leave the female/young subgroup of the troop at two and a half to three years of age. From here the adolescent males will form their own subgroup in the troop, consisting of immature males that cannot compete with the older males for dominance. At around five years of age, the males will join the mature male subgroup and begin to compete for dominance (Gibson,Kuehl, and Ruiz, 2005).
Breeding interval: Bolivian squirrel monkeys breed once yearly.
Breeding season: Breeding is restricted to 3 months of the year, synchronized by females in a group.
Average number of offspring: 1.
Range gestation period: 152 to 172 days.
Range weaning age: 4 to 6 months.
Average time to independence: 1 years.
Range age at sexual or reproductive maturity (female): 2.5 to 3 years.
Average age at sexual or reproductive maturity (male): 5 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization ; viviparous
Parental investment by Bolivian squirrel monkeys is taken on entirely by the females. Upon birth of the infant, the mother protects her offspring and provides entirely for it. Responsibilities include dorsal carriage, cleaning, retrieval, and nursing. Mothers are protective of their offspring and don't let them wander far.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); post-independence association with parents; extended period of juvenile learning; inherits maternal/paternal territory
- Schrier, A. 1977. Behavioral Primatology. Hillsdale, NJ: Lawrence Erlbaum Associates, Inc..
- Carpenter, C. 1973. Behavioral Regulators of Behavior in Primates. Lewisburg, PA: Bucknell University Press.
- Bourne, G. 1971. The Ape People. New York: Academic Press.
- Hinde, R. 1983. Primate Social Relationships: An Integrated Approach. Oxford: Blackwell Science Ltd..
- Gibson, S., T. Kuehl, J. Ruiz. 2005. "Squirrel Monkey Breeding and Research Resource" (On-line). Accessed November 23, 2005 at http://www.smbrr.org/.
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Molecular Biology and Genetics
Molecular Biology
Barcode data: Saimiri boliviensis
There are 2 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
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Statistics of barcoding coverage: Saimiri boliviensis
Public Records: 2
Species: 5
Species With Barcodes: 1
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Conservation
Conservation Status
IUCN Red List Assessment
Red List Category
Red List Criteria
Version
Year Assessed
Assessor/s
Reviewer/s
Contributor/s
Justification
History
- 2003Least Concern(IUCN 2003)
- 1996Lower Risk/least concern
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Conservation Status
This species has not currently been evaluated by international conservation databases. They rely on intact rainforests, so are vulnerable to deforestation.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
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Trends
Population
Bolivia
Wallace et al. (2000) recorded primate encounter rates along transects at eight sites in the Rios Blanco y Negro Wildlife Reserve, Santa Cruz, Bolivia. Saimiri boliviensis was seen at two of the sites with an encounter rate of 0.2 and 0.7 groups/10 km, or 4.9 and 9.8 individuals/10 km, respectively. In the Beni Reserve, Painter et al. (1995) recorded an encounter rate of 0.6 groups or 20 individuals/10 km. In the Bosque Chimanes, Rumiz and Herrera (1994) recorded 1.7 groups or 36.4 individuals/10 km. Wallace et al. (1998) did not find squirrel monkeys in the Noel Kempf Mercado National Park where they surveyed (east of the Río San Martín, Santa Cruz Department).
Brazil
Peres (1997) estimated densities of S. boliviensis boliviensis at várzea (white-water flooded forest) in the Brazilian Amazon: Sacado do Condor 70.7 individuals/km²; Boa Esperança 149.2 individuals/km². They are less abundant in terra firma forest: Porongaba 11.3 individuals/km²; Kaxinawá Reserve: 36.4 individuals/km²; Penedo 19.1 individuals/km²; Altamira 28.7 individuals/km².
Peru
Terborgh (1983) estimated a density of 50 individuals/km² in Manu National Park, Peru.
Population Trend
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Threats
Threats
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Management
Conservation Actions
Saimiri boliviensis boliviensis
Bolivia
Madidi National Park (1,571,500 ha)
Manuripi National Reserve (1,884,000 ha) (in range)
Ríos Blanco y Negro National Reserve (1,423,900 ha) (Wallace et al. 2000)
Beni Biosphere Reserve (135,000 ha) (Painter et al., 1995; Wallace et al. 2000)
Amboro National Park
Carrasco National Park
Isibore-Secure National Park and Indigenous Territory
Pilon Lajas Indigenous Teriitory and Biosphere Reserve
Brazil
Serra do Divisor National Park (southern part, in range)
Rio Acre Ecological Station (79,418 ha)
Peru
Tambopata National Reserve (262,315 ha)
Bahuaja-Sonene Community Reserve (1,091,416 ha)
Manu National Park (1,532,806 ha) (Terborgh 1983; Aquino and Encarnación 1994
Yanachaga-Chemillén National Park (122,000 ha) (Aquino and Encarnación 1994)
Saimiri boliviensis peruviensis
Peru
Pacaya Samiria National Reserve (2,080,000 ha) (Hershkovitz 1984; Aquino and Encarnación 1994)
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Relevance to Humans and Ecosystems
Benefits
Economic Importance for Humans: Negative
Bolivian squirrel monkeys have no adverse effects on humans.
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Economic Importance for Humans: Positive
Bolivian squirrel monkeys are sometimes captured for food or for the pet trade. There was once a large trade in squirrel monkeys in the United States for both biomedical research and as entertainment (zoos and pet markets). Between 1968 and 1972, more than 173,000 squirrel monkeys were used for medical research. Regulations were then established that reduced trade in squirrel monkeys for non-research reasons (Nowak, 2000).
Positive Impacts: pet trade ; food ; body parts are source of valuable material; research and education
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Wikipedia
Black-capped squirrel monkey
The black-capped squirrel monkey (Saimiri boliviensis) is a South American squirrel monkey, found in Bolivia, Brazil and Peru. This South American monkey can be found at the Ellen Trout Zoo.
Subspecies
- Bolivian squirrel monkey, Saimiri boliviensis boliviensis
- Peruvian squirrel monkey, Saimiri boliviensis peruviensis
References
- ^ Groves, C. (2005). Wilson, D. E.; Reeder, D. M. eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 138. OCLC 62265494. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3/browse.asp?id=12100285.
- ^ Wallace, R. B., Cornejo, F. & Rylands, A. B. (2008). "Saimiri boliviensis". IUCN Red List of Threatened Species. Version 2011.2. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/41536. Retrieved 19 January 2012.
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