Reddish-Brown Bearded Saki, Chiropotes sagulatus
REDDISH-BROWN BEARDED SAKI
Chiropotes sagulatus
Geographic Distribution and Habitat
The reddish-brown bearded saki, Chiropotes sagulatus, also known as the Guianan bearded saki and the reddish-brown cuxiú, is native to the tropical rainforests of Brazil, Guiana, French Guiana, and Suriname. They prefer terra firme forests — that is, rainforests that do not flood— and are absent from especially wet areas. They are abundant throughout their range, thriving in the well-protected rainforests of this region.
The bearded sakis of the genus Chiropotes have been reclassified multiple times. Some scientists in the past have considered reddish-brown bearded sakis to be a subspecies of the red-backed bearded saki (C. chiropotes), but today they are commonly considered to be their own unique species, joining the four others in their genus.
Bearded sakis are closely related to, but taxonomically distinct from, saki monkeys of the genus Pithecia. Some researchers have called for adopting the local name “cuxiú” in place of “bearded saki” to reduce confusion between the two primate groups.
Size, Weight, and Lifespan
Female reddish-brown bearded sakis measure about 15.2 inches (39 cm) from the head to the base of their tail. Males are just a bit longer, at about 15.7 inches (40 cm) in length on average. Females weigh about 5.6 pounds (2.6 kg) and males weigh about 6.8 pounds (3.1 kg). Bearded sakis can live until their late teens in captivity.
Appearance
Reddish-brown bearded sakis are medium-sized primates that are covered in long, almost woolly hair. They have a distinctive appearance thanks to their coronal tufts — two large orb-shaped tufts of hair on the top of their head. They also have long beards — even the females, although those of males are generally longer and thicker. Their woolly hair is especially long on their shoulders and arms, giving them the appearance of wearing a cape. As their name implies, reddish-brown breaded sakis are, well, reddish-brown over most of their body. Their head, tail, and lower limbs are usually black. Their tail is particularly impressive — covered in thick fur, it resembles a squirrel’s fluffy tail. Their teeth are specially adapted to their diet, allowing them to crack open hard-shelled fruits and seeds.
Diet
Reddish-brown bearded sakis are primarily seed eaters. They also eat fruits, flowers, and other plant parts, and are known to eat more than 175 plant species. They also actively hunt insects and, in periods of fruit scarcity, they spend nearly 40% of their feeding time eating insects. They sometimes consume soil from termite nests as a source of minerals. Their diet may help them to weather seasonal shortages of food, as nuts and seeds often remain abundant even in the dry season, and they have adaptable diets that can change depending on food availability. The only periods of food shortage they typically experience are during the change of seasons.
Behavior and Lifestyle
Reddish-brown bearded sakis are active, averaging about 0.6-1.9 miles (1-3 km) of movement in a day, and each group inhabits a home range upwards of 1,850 acres (750 ha). They move about quadrupedally — on all fours — and leap from branch to branch. They typically get a running start to their leaps and land on their hands and feet. They do not often climb. Bearded sakis sometimes practice suspensory feeding — that is, feeding while hanging from branches. While their tail is not prehensile and they cannot hang from it, they often use it as support while hanging from their arms.
Bearded sakis tend to spend their day in the higher parts of the canopy. They wake up and go to sleep with the sun, making them diurnal — awake during the day. They typically spend most of their day on the move and eating. In between, they also engage in social behavior and rest.
At night, they find a tall tree to curl up in, wrapping their fluffy tail around themselves like a blanket. Bearded sakis often use the same areas to travel, like humans use roads. They like to travel on the tops of ridges, as they have fewer obstacles and allow for faster travel, and the sightlines from tall ridges may help the sakis to locate fruiting trees and keep an eye out for predators.
Bearded sakis are born with prehensile tails that come in handy when keeping a tight grip on their mother. However, when they are about two months old, their tail loses its prehensility.
Due to their large home ranges and long daily travel distances, bearded sakis are often a focus of studies on movement ecology. Curiously, one such study found that reddish-brown bearded sakis turn to the left more often than to the right.
Reddish-brown bearded sakis live in large groups, which can have more than 50 members. There are multiple adult males and females in the group. The large group usually splits apart into smaller subgroups during the day to forage — a grouping style known as “fission-fusion” which is likely used to reduce competition for food. While feeding, even within a subgroup, individuals tend to spread out, usually keeping at least 16 feet (5 m) between each other.
Reddish-brown bearded sakis either have no hierarchy system or only a weak hierarchy. Males within a group tend to get along very well, and bonds between adult males can be close. In all-male bachelor groups, these bonds tend to be even tighter. Some studies even suggest that males prefer the company of other males — one study found that 65% of grooming pairs were composed of two males, and that 66% of the time, the physically closest individual to any given male is another male. This is at odds with many other primate species, whose male-to-male relationships are often tenuous at best, and downright antagonistic at worst.
Reddish-brown bearded sakis communicate vocally using a variety of sounds, such as whistles. When they need to be silent, such as when a predator is nearby, they wag their tails to communicate to their groupmates. Bonding interactions are very important to maintain cohesion in their large groups. These interactions include playful chasing and wrestling and “piling up” on each other, behaviors that have only been observed between males. Males also display sociosexual behaviors with each other, like mounting. Grooming is used by both sexes as a form of bonding and social cohesion, with the added benefit of removing parasites and other debris.
There is little male-to-male competition, called intrasexual competition, within reddish-brown bearded saki groups. Older males do not tend to be territorial about mating opportunities and tolerate matings by younger males without fuss. Reproduction is seasonal, with births usually occurring during the rainy season when food is abundant.
There is about a five-month gestation period. Babies ride on their mother’s belly for the first month of their life and then move to riding on her back. Researchers use this behavior to roughly age young babies — if they are riding on their mother’s belly, they are likely under a month old.
While it is not yet known for certain, it has been hypothesized that males, along with females, may remain with the group they were born into, a behavior known as philopatry. While this is a common practice for female primates, it is less common among males, who, in many species, leave their group upon reaching sexual maturity. However, the lack of male intrasexual competition may play a role in young males staying with their group. The uncommon practice of tight-knit male bonds, low intrasexual competition, and male philopatry may be an evolutionary strategy to help protect the group as a whole. Even if a male misses out on mating opportunities, for example, he may be better off in the long run — and more likely to pass on his genes — by working together with the other males to protect the group.
Reddish-brown bearded sakis are sympatric — that is, they share the same habitats as — a number of other primates, including spider monkeys (Ateles spp.) and capuchin monkeys (Cebus spp.). Aggression sometimes occurs with capuchin monkeys over competition for food. Aggression is less common with spider monkeys, as the two primate species tend to feed on fruits of different ripeness. Predators of bearded sakis include arboreal snakes, such as boa constrictors, and birds of prey, like harpy eagles.
The International Union for Conservation of Nature lists the reddish-brown bearded saki as Least Concern (IUCN, 2015) appearing on the IUCN’s Red List of Threatened Species. Reddish-brown bearded sakis exemplify the concept that when habitat is protected, species populations are generally stable. Reddish-brown bearded sakis are widespread and their habitat is not particularly vulnerable to deforestation. By 2048, less than 5% of the forest habitat in their range is predicted to be lost — a low enough amount that conservation scientists are not worried about the future of the species.
Fortunately for reddish-brown bearded sakis, they are not at significant risk from any major threats. They are hunted locally around villages, though not to the extent that their population is jeopardized. Like any primate — or indeed, any other species — they are fully dependent on their habitat for their survival. Luckily, their habitat is well-protected, and therefore habitat loss is not a major risk.
Reddish-brown bearded sakis are listed in Appendix II of the Convention on International Trade in Endangered Species (CITES), an international agreement between governments whose goal is to ensure that international trade in specimens of wild animals and plants does not threaten their survival.
Reddish-brown bearded sakis owe their stable population to the numerous protected areas that guard the habitat within their range. They occur in the Central Suriname Nature Reserve, Sipaliwini Nature Reserve, and the Wai-wai Community-Owned Conservation Area, among others. The latter was established in 2007 by the Wai-wai people of Masakenari, in southern Guiana. The conservation area is 1.5 million acres (625,000 ha) in size and is managed by the locals who reside there. The rules of the conservation area allow the indigenous community to sustainably utilize the natural resources within while protecting it from exploitation. This has resulted in a harmonious relationship between the local people and the many animal species they live amongst, including the reddish-brown bearded saki.
More research focused on reddish-brown bearded sakis is needed to more fully understand their life history and behavior. Research in the past has often treated the Chiropotes genus as a homogeneous group, without differentiating between the unique species. Conservationists have called for more genetic research on reddish-brown bearded sakis which could help to shed light on their dispersal patterns and determine whether males tend to stay with their natal group. Answering this question using field observation has been a challenge because it is very difficult for researchers to tell individuals apart visually.
- https://www.iucnredlist.org/species/70330167/191707709
- https://www.iatp.org/news/wai-wais-ink-historic-forest-conservation-deal-guyana
- https://primate.wisc.edu/primate-info-net/pin-factsheets/bearded-saki/
- Boyle, S. A., Lourenço, W. C., da Silva, L. R., Spironello, W. 2023. Spatial Ecology of Reddish-Brown Cuxiú Monkeys (Chiropotes sagulatus, Pitheciidae) in an Isolated Forest Remnant: Movement Patterns and Edge Effects. Diversity 15(6): 731. https://doi.org/10.3390/d15060731
- Gregory, T., Mullett, A. and Norconk, M.A. 2014. Strategies for navigating large areas: A GIS spatial ecology analysis of the bearded saki monkey, Chiropotes sagulatus, in Suriname. Am. J. Primatol., 76: 586-595. https://doi.org/10.1002/ajp.22251
- Shaffer, C.A. 2013. Activity Patterns, Intergroup Encounters, and Male Affiliation in Free-Ranging Bearded Sakis (Chiropotes sagulatus). Int J Primatol 34: 1190–1208. https://doi.org/10.1007/s10764-013-9727-3
- Shaffer, C.A. 2013. Feeding Ecology of Northern Bearded Sakis (Chiropotes sagulatus) in Guyana. Am. J. Primatol., 75: 568-580. https://doi.org/10.1002/ajp.22134
- Tremaine, G. L. 2011. Socioecology of the Guianan bearded saki, Chiropotes sagulatus [Doctoral dissertation, Kent StateUniversity]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1300284081
Written by K. Clare Quinlan, July 2024