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Pitheciasaki monkeys

By Sierra Larson

Diversity

The genus Pithecia, more commonly known as Saki monkeys, are New World Monkeys native to neotropical South America. There are currently 16 described species and can be found throughout tropical rainforests in the Amazon Basin. Pithecia are medium-sized primates that are characterized by their long, thick fur that covers their whole body. Their tales are non-prehensile and are often at a 1:1 ratio with their body. The genus prefers mature forests and they spend the majority of their time foraging in the canopy, and trips to the forest floor are rare. Their conservation status is unknown as they are very elusive in the wild, but their population is expected to be in decline due to increasing habitat loss. (Marsh, 2014; Palminteri and Peres, 2012)

Geographic Range

Saki monkeys are distributed across neotropical South America in tropical forests in the Amazon Basin. They range as far north as the Guiana Shield and as far south as Northern Bolivia. (Marsh, 2014)

Habitat

Saki monkeys are arboreal and spend all their time in the canopy. While they can be found in secondary forests, they are more likely to persist in mature forests with variable habitat including terra firme, palm swamps, and flooded forest. Their large geographic distribution is attributed to their ability to persist in a range of forests types. Sakis are diurnal and sleep in trees at different designated sleeping spots during the night. They are very elusive and rarely ever venture to the forest floor. (Palminteri and Peres, 2012)

Systematic and Taxonomic History

The genus Pithecia consists of about 16 recognized species. The taxonomy of this genus has been widely difficult to establish due to a lack of genetic information, misuse of common names, misunderstandings of sexual dimorphism, and imprecise type localities. In a taxonomic review of the genus in 2019, researchers found evidence for two morphologically diagnosable groups within genus Pithecia (P. irrorata and P. vanzolinii).The taxonomic uncertainty within the genus Pithecia proves that more studies need to be done to evaluate the revise the taxonomic status of genus. (Eduardo Serrano-Villavicencio, et al., 2019)

  • Synapomorphies
    • Saki monkeys have long bushy hair that can raise into hackles and make them look bigger than they actually are when they feel threatened.
    • Sakis scent mark branches and leaves with scent glands that are located on their chest or throat.
    • Sakis have a 1:1 tail to body ratio, and their tails are used for balance while jumping, leaping, and running through the trees.

Physical Description

Saki monkeys are medium sized primates and the smallest of the Pitheciidae family. Sakis have a wide range in body length and their tails are often a 1:1 ratio with their body length. Females are slightly smaller than males in overall size and weight. Sakis have long, rough hair that covers their entire body, giving them a distinct shaggy look and oftentimes they appear to have "bangs." Sexual dimorphism varies among species but males and females generally have distinct pelage markings. Both sexes have throat glands that are used for scent marking. Sakis do not have prehensile tails and they can be seen walking, running, climbing, and leaping as their main form of locomotion. (Marsh, 2014)

  • Sexual Dimorphism
  • male larger
  • sexes colored or patterned differently

Reproduction

Species in the genus Pithecia live in monogamous social groups. While not much information is known on their reproductive behaviors in the wild, captive populations have been shown to be more monogamous than wild populations. Larger groups tend to be polygamous or polyandrous given more than one primary breeding female and male are present in the group. (Norconk, 2006)

During mating season, male saki monkeys make mating calls to the females in wild populations. Both males and females become sexually mature at around three years of age, but females can take longer, given the time their ovarian cycle becomes regular. Females typically bear only one offspring and the gestation period lasts on average 146 days. (Norconk, 2006; Waters, 1995)

Infant saki monkeys will cling to the mother's thigh for the first month of their life. Then they relocate to the mothers back for the next three months which allows for better mobility given the size of the growing infant. Once the infant reaches the age of about five months, it stops clinging from its mother and moves freely within the group. The offspring still weans from its mother until it can survive on its own. (Norconk, 2006; Norconk, 2006; Waters, 1995)

  • Parental Investment
  • female parental care
  • 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
  • extended period of juvenile learning

Lifespan/Longevity

While not much is known on the longevity of most Pithecia species, some species can live up to 36 years in captivity, but the average lifespan among sakis in the wild is around 15 years. (de Magalhaes and J. Costa, 2009)

Behavior

Saki monkeys are social and travel through the canopy in small groups of 2 to 9 individuals. Their daily activities include moving from sleep trees in early morning to forage for fruit, then returning to another sleep tree in the evening, often accompanied by another saki monkey group. Sakis spend anywhere from 9 to 12 hours moving through the canopy. Allogrooming is practiced extensively throughout the day and is most commonly seen between mothers and infants. Saki monkeys have a variety of specialized vocalizations including trills, whistles, grunts, roars, and squeaks, which are used for various intensity dependent aggressions. (Walker, 2005; Waters, 1995)

Communication and Perception

Sakis communicate to each other and to other groups by loud vocalizations, and often establish their territories when male and female pairs, typically the breeding individuals, make loud calls. Sakis have scent glands on their chests/throats and adult males mark their territory using a combination of urine and scent gland markers. (Norconk, 2006; Waters, 1995)

Food Habits

Species in the genus Pithecia are specialized for eating the seeds of fruiting bodies. Apart from seeds they consume fruits, flowers, leaves, and nuts. Leaves are eaten more often in the dry season when fruit is not available. Since their diet lacks protein, they have been known to eat insects to make up for their high fat intake. (Norconk, 2006; Norconk and Conklin-Brittain, 2004)

Predation

Saki monkeys make alarm calls when a predator is near the group. Once the first alarm call is made, the rest of the group joins. The group stays motionless after making the call so they are undetectable within the canopy, then they move away from the threat. Sakis have both terrestrial predators like jaguars and anacondas, as well as avian predators like the harpy eagle. (Norconk and Gleason, 2002)

Ecosystem Roles

Sakis play a major role in seed dispersal. Some species of sakis, including Pithecia pithecia, have been recorded for having parasites like roundworm, heartworm, and the Mayaro virus. (Thoisy, et al., 2003)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Sakis are commonly hunted and captured for their meat in the Amazon basin. They are also trapped for the pet trade, although they don't live long when kept as a pet because their diet requirements are hard to meet. While there are only a handful of Pithecia species in captivity, they attract many visitors in zoos. Sakis that have been habituated near hotels and ecolodges in the Amazon are also big tourist attractions. (Nowak, 1991)

Economic Importance for Humans: Negative

The adverse effects saki monkeys have on humans is unknown. Studies have shown that sakis can carry diseases that can be transmitted to humans, including the human herpesvirus (HHVI) and hepatitis. (Bauer, et al., 2018; Nowak, 1991)

Conservation Status

The conservation status of most saki monkeys are of least concern, but there is a data deficiency for almost all saki species, including Pithecia irrorata, Pithecia milleri, and Pithecia rylandsi, and current populations are unknown. However, increasing habitat loss and fragmentation due to deforestation and gold mining in the Amazon is assumed to be causing a rapid decline in their populations. (Marsh, 2014)

  • IUCN Red List [Link]
    Not Evaluated

Contributors

Sierra Larson (author), Colorado State University, Audrey Bowman (editor), Colorado State University.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

aposematic

having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

causes or carries domestic animal disease

either directly causes, or indirectly transmits, a disease to a domestic animal

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

insectivore

An animal that eats mainly insects or spiders.

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polyandrous

Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).

polygynous

having more than one female as a mate at one time

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

References

Barnett, A., S. Boyle, M. Norconk, S. Palminteri, R. Santos, L. Veiga, T. Alvim, M. Bowler, J. Chism, A. Di Fiore, E. Fernandez-Duque, A. Guimaraes, A. Harrison-Levine, T. Huagaasen, S. Lehman, K. Mackinnon, F. De Melo, L. Moreira, V. Moura, C. Phillips, L. Pinto, M. Port-Carvalho, E. Setz, C. Shaffer, I. Da Silva, S. Da Silva, R. Soares, C. Thompson, T. Vieira, A. Vreedzaam, S. Walker-Pacheco, W. Spironello, A. Maclarnon, S. Ferrari. 2013. Terrestrial Activity in Pitheciins (Cacajao, Chiropotes, and Pithecia).. American Journal of Primatology, 74/12: 1106-1127.

Bauer, K., J. Steeil, E. Adkins, A. Childress, J. Wellehan, K. Kerns, S. Sarro, K. Holder. 2018. Management of Ocular Human herpesvirus 1 infection in a White-faced Saki Monkey (Pithecia pithecia). Comparative Medicine, 1/68(4): 319-323.

Eduardo Serrano-Villavicencio, J., C. Hurtado, R. Vendramel, F. Do Nascimento. 2019. Reconsidering the taxonomy of the Pithecia irrorata species group (Primates: Pitheciidae).. Journal of Mammalogy, 100: 130-141.

Hershkovitz, P. 1987. The taxonomy of South American sakis, genus Pithecia (Cebidae, Platyrrhini): a preliminary report and critical review with the description of a new species and a new subspecies.. American Journal of Primatology, 12/4: 387-468.

Marsh, L. 2014. A Taxonomic Revision of the Saki Monkeys, Pithecia Demarest, 1804.. Neotropical Primates, 21: 1-163.

Norconk, M. 2006. Long-term Study of Group Dynamics and Female Reproduction in Venezuelan Pithecia pithecia. International Journal of Primatology, 27: 653-674.

Norconk, M., N. Conklin-Brittain. 2004. Variation on frugivory: The diet of Venezuelan white-faced Sakis. International Journal of Primatology, 25/1: 1-26.

Norconk, M., T. Gleason. 2002. Predation risk and antipredator adaptations in white-faced sakis, Pithecia pithecia. Pp. 169-183 in L Miller, ed. Eat or be eaten: predator sensitive foraging among primates. Cambridge, United Kingdom: Press Syndicate of the University of Cambridge.

Nowak, R. 1991. Walker's Mammals of the World, Volume 1. Baltimore: The Johns Hopkins University Press.

Palminteri, S., C. Peres. 2012. Habitat Selection and Use of Space by Bald-Faced Sakis (Pithecia irrorata) in Southwestern Amazonia: Lessons from a Multiyear, Multigroup Study. International Journal of Primatology, 33/2: 401-417.

Palminteri, S., G. Powell, C. Peres. 2016. Determinants of Spatial Behavior of a Tropical Forest Seed Predator: The Roles of Optimal Foraging, Dietary Diversification, and Home Range Defense.. American Journal of Primatology, 78/5: 523-533.

Thoisy, B., J. Gardon, R. Salas, J. Morvan, M. Kazanji. 2003. Mayaro virus in wild mammals, French Guiana. Emerging Infectious Diseases, 9/10: 1326-1329.

Walker, S. 2005. Leaping behavior of Pithecia pithecia and Chiropotes satanas in eastern Venezuela. American Journal of Primatology, 66/4: 369-387.

Waters, S. 1995. A review of social parameters which influence breeding Pithecia pithecia in white-faced saki in captivity. International Zoo Yearbook, 34/1: 147-153.

de Magalhaes, J., J. Costa. 2009. A database of vertebrate longevity records and their relation to other life-history traits.. Journal of Evolutionary Biology, 22/8: 1770-1774.

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