GUIANA SPIDER MONKEY

Ateles paniscus

Geographic Distribution and Habitat
Guiana spider monkeys, also known as black spider monkeys or red-faced spider monkeys, are native to South America, north of the Amazon River. They are found in Brazil, French Guiana, Guyana, Suriname, and possibly Venezuela. If they are present in Venezuela, they would be found at the eastern tip, since there are no physical or habitat barriers on the Venezuela-Guiana border. Their presence has not been confirmed there, however. Other small populations have been studied in Peru and Bolivia.

Guiana spider monkeys are found in dense forests isolated from human populations. They spend most of their time in the upper canopy and prefer forests with canopy heights higher than 82 feet (25 m).

Guiana spider monkey range, IUCN 2019

Size, Weight, and Lifespan
Sexual dimorphism in Guiana spider monkeys is minimal. This means that males and females only differ slightly in size. The head-to-body length in males is roughly 21.9 inches (55.7 cm), while females measure 21.7 inches (55.2 cm) in length. Males weigh about 20 pounds (9.1 kg) and females weigh about 19 pounds (8.4 kg).

The oldest Guiana spider monkey in the wild has lived past 37 years of age; however, more field research is needed to draw more precise conclusions on average lifespans for wild populations. In captivity, the oldest recorded Guiana spider monkey has lived up to 46 years.

Appearance
The long, black, glossy hair of Guiana spider monkeys covers their entire bodies, except for their faces. Their long hair easily distinguishes them from other spider monkey species; however, there are other defining characteristics as well. Adults have reddish or pink-skinned faces with very few white hairs around their nose and chin. Infants are born with darker-skinned faces, which lighten as they grow older. Their hands and feet are covered in long black hair. Their hair is quite unique since it is longer than that typically found on primates.

Spider monkeys are large New World monkeys with long gangling arms and legs. Guiana spider monkeys are the largest of the spider monkey species. Their long tails prehensile tails are used for balance and act as an additional limb, allowing them to move with ease and efficiency through the canopy. It also allows them to suspend while feeding with the tail supporting their entire weight while their hands are free to forage for food. The underside of the tip of the tail has a patch of skin with a unique pattern similar to a fingerprint.

The body structure and other morphological characteristics of Guiana spider monkeys are adaptations for a completely arboreal lifestyle. Their elongated arms allow them to brachiate, a hand-over-hand swinging motion used while traveling through trees. In addition to their long arms, they have long hook-like fingers that assist with movement in the forest canopy and facilitate brachiation as they swing from branch to branch. Guiana spider monkeys walk, run, and clamber quadrupedally.

Like all spider monkeys, Guiana spider monkeys lack an external thumb. They do, however, have a shortened thumb. This does not mean that they are less evolved than other primates; their ancestors actually had an opposable thumb. Over time their thumb shrank in size compared to other finger bones due to lack of use in their environment. Given their athletic talent for swinging through the canopy, thumbs would simply be in the way.

What Does It Mean?

Brachiation:
Also called arm swinging, is a form of arboreal locomotion in which primates swing from tree limb to tree limb using only their arms.

Estrus:
A recurring period of sexual receptivity and fertility in many female mammals.

​Prehensile tail: 
The tail of an animal that has adapted to be able to grasp or hold objects.

​Sexual dimorphism:

Distinct difference in size or appearance between the sexes of an animal in addition to difference between the reproductive organs themselves.

Visit the Glossary for more definitions

Photo credit: Hans Hillewaert/Creative Commons

Diet
Guiana spider monkeys are very much a canopy species; they spend most of their time in the middle to upper levels of the canopy, hanging from branches​ and feeding. They are highly frugivorous and feed largely on mature fruits, which make up 83% of their diet. They also eat young leaves and flowers, ​especially during the beginning of the dry season when fruit is scarce. Additionally, they can be found munching on seeds, floral buds, roots, bark, wood, honey,​ and occasionally insects. 

Behavior and Lifestyle
Spider monkeys are diurnal and enjoy jumping and playing in the upper canopy during the day. At night, they sleep in the canopy for protection from predators. Cleverly, they choose to sleep close to food sources.

Extremely agile, spider monkeys are sometimes referred to as the “trapeze artists of the forest.” They primarily travel through the forest canopy using distinct styles of locomotion: quadrupedal walking and running, suspensory swinging or brachiating, climbing, bipedalism, and leaping. Quadrupedal walking/running and climbing are mostly used during travel; however, climbing is also a very common locomotion pattern while feeding.

What scientists refer to as “suspensory behaviors” are important during feeding. This is when the monkeys use their tails as an extra limb, which allows them to have hands free for grabbing fruits and leaves, and also allows them to move more efficiently through tree branches and avoid ground predators. It is common for spider monkeys to stop and rest while eating, frequently in a seated or reclined position.

Traveling and feeding take up about 26–29% of their daily activity budget, with most of their time spent resting (about 45%). During the dry season, resting periods can be longer due to a decrease in food availability.

Fun Facts

An infant starts to use his tail within just a few days after he’s born, wrapping it around his mother’s tail like a seat belt while he rides on his mother’s back.

Guiana spider monkeys spend most of their life in trees and are hardly ever seen on the ground. 

Spider monkeys are extremely agile and are sometimes referred to as the “trapeze artists of the forest.”

Daily Life and Group Dynamics 
Guiana spider monkeys live in a fission-fusion social system in which individuals splinter off into small groups or sub-groups whose members belong to a larger troop, or unit-group. There is fluid movement between sub-groups and the unit-group. Throughout the day, sub-groups forage together within a core area of the unit-groups home range. Group compositions frequently change throughout the day, but they typically consist of a male, a female, and their offspring. Often times individual females have their own territory within the groups’ home range and rarely associate with other females.

The unit-group usually consists of 15 to 20 individuals. They interact peacefully with little to no aggression. When two different troops of spider monkeys come together, the males from each troop display agonistic behaviors in order to defend their territory. This usually occurs from a distance and rarely involves physical contact, which indicates that groups respect distinct territorial boundaries.

Dominance relationships between Guiana spider monkeys are not well known. However, some females have been observed to have a more active leading role than males and are considered dominant in their subgroups. In most cases, the foraging routes taken by females are planned, far more advanced, and often different from day to day. This planned behavior causes the females to have a greater variety in diet than males. Other group members follow the dominant female on her foraging route.

Little data is available on dispersal patterns of the Guiana spider monkey. Some research suggests that males remain in their natal group while females transfer between groups for mating opportunities. In Suriname, female Guiana spider monkeys were observed breaking away from their subgroups to join neighboring troops. This would last anywhere from several hours to overnight.

Communication
Spider monkeys have many forms of communication. They vocally communicate through grunting, whistling, squeaks, trills, and barking calls. Barking calls are used to warn others of predators as well as to clarify where food can be found. Other common vocalizations are “sobs” or “tee-tee” calls.

Much of the information found on Guiana spider monkey communication comes from Suriname. One of the most common calls emitted by adult males are the long-calls or “whoops” and serve as the main communication between neighboring subgroups. These whoops can be heard at distances up to .621 mi (1 km) on the forest floor; when in the canopy, sounds can travel up to 1.24 mi (2 km). 

Physical communication is also very common. Guiana spider monkeys will scratch their chests, shake tree branches, swing their arms, and throw objects from trees. When greeting another monkey, they smell each others’ chests and genital regions. This is presumed to be a means of identifying one another and recalling past relationships.

Reproduction and Family
Guiana spider monkeys are polygynandrous; that is, both males and females have multiple mates. Courtship often includes wrestling and playing with members of the opposite sex. Other behaviors include vocalizations such as growling and panting as well as head-shaking.

When a female is in estrus, a male smells or licks the potential mates’ genital region. Females often choose their mate by sitting on a specific male’s lap. If the male seems uninterested, she moves on and repeats the same behavior to the next potential mate. If a male is interested, he wraps his legs around hers.

Spider monkeys reproduce every 3 to 4 years, resulting in approximately four offspring throughout a female’s lifetime. Much of the infants’ lives are spent with their mother. After birth, babies spend the first 2 to 3 months clinging to their mother. Sometimes this can last up to 4 to 5 months. At 6 to 9 months, they ride on their mother’s back. At around 10 months, they begin to explore their environment on their own, remaining within about 16 feet (5 m) of their mother. At about 15 to 18 months, they begin foraging without their mothers’ help.

Paternal investment for a male Guiana spider monkeys is minimal. They do defend their territories and they defend their mates from intruding spider monkey groups. At 4 years of age, young males spend less time with their mother and start to follow adult males in their groups.

Ecological Role
Due to their specialization in fruit-eatings, Guiana spider monkeys tend to swallow whole fruits and intact seeds. This makes them very important seed dispersers for many trees and lianas.​ A study by Van Roosmalen (1985) found that Guiana spider monkeys disperse seeds of at least 138 species through their ingestion and defecation. The study also found that 10 additional seed species were dispersed when monkeys carried them away from the mother tree and dropped them, whether accidentally or intentionally.

Conservation Status and Threats
The Guiana spider monkey is listed as Vulnerable by the International Union for Conservation of Nature, appearing on the IUCN’s Red List of Threatened Species (IUCN, 2019). Some populations have experienced heavy impact from hunting and loss of suitable habitat, which has led to a population decline of at least 30%.

With continued hunting and habitat loss, similar population decline over the next two generations is likely. Much of this habitat loss is due to expanding agriculture, ranching, mining, and hydroelectric road construction. The predicted amount of suitable habitat loss by 2050 could be 40% or more. It is anticipated that Guiana spider monkey population density could face declines of as much as 75% in areas of light hunting—and up to 90% in heavily hunted areas. 

Conservation Efforts
The Guiana spider monkey occurs in a number of protected nature reserves, state parks, and forests in Brazil, French Guiana, Guyana, and Suriname. They are listed on the Appendix II of the Convention on International Trade in Endangered Species (CITES).

With continuous road construction and the exploitation of indigenous lands, a decrease in Guiana spider monkey populations can be anticipated. Government protection policies have been relaxed are are rarely enforced. An increase in land/water management and species management is needed to ensure populations are stable and not highly stressed. Further research and monitoring on this species is also needed. Research on population size and distribution can help raise awareness to the general public, educators, governments, and others. Monitoring their population trends can help ensure their long-term survival in the wild.

References:

  • http://pin.primate.wisc.edu/factsheets/entry/black_spider_monkey/behav
  • http://www.theprimata.com/ateles_paniscus/
  • https://www.lamar.edu/arts-sciences/biology/jungle-critters/jungle-critters-2/spider-monkey/
  • https://www.iucnredlist.org/species/2283/17929494
  • Mittermeier, R. A. 1977. Distribution, Synecology, and Conservation of Surinam Monkeys. Ph.D. Thesis, Harvard University.
  • Van Roosmalen, M. G. M. 1985. Habitat preferences, diet, feeding strategy and social organization of the black spider monkey (Ateles paniscus paniscus Linnaeus 1758) in Surinam. Acta Amazonica 15(3-4): 1–238.
  • Youlatos D. 2002. Positional Behavior of Black Spider Moneys (Ateles paniscus) in French Guiana. International Journal of Primatology. 23:5. 1071-1093.
  • Rosenberger A.L., Halenar L., Cooke S.B., Hartwig W.C. 2008. Morphology and evolution of the spider monkey, genus Ateles. Spider Monkeys: Behavior, Ecology and Evolution of the Genus Ateles. 9:36. 19-49.

Written by Tara Covert, June 2020