Bearded saki (Chiropotes satanas)

Also known as: Black saki, black-bearded saki, brown-bearded saki
Synonyms: Chiropotes satanas satanas
Spanish: Cuxiú-preto
GenusChiropotes (1)
SizeMale head-body length: 40 – 48 cm (2)
Female head-body length: 38 – 41 cm (2)
Male tail length: 40- 42 cm (2)
Female tail length: 37 – 42 cm (2)
Male weight: 2.2 – 4.0 kg (2)
Female weight: 1.9 – 3.3 kg (2)

Classified as Critically Endangered (CR) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

With a head of thick, black hair and a dense beard framing the face (4), bearded sakis are highly distinctive monkeys. The coat is mostly black, with highlights of light yellow brown to dark brown on the back and shoulders (2). The bushy fox-like tail (a characteristic of all monkey species in the Pitheciidae family (5)), is also black, and unlike some other monkeys, it is only capable of grasping in infant bearded sakis (2). Female bearded sakis are slightly smaller than males (2), and males can also be distinguished by their bulging foreheads (6). The scientific name Chiropotes is a combination of Greek words meaning ‘hand-drinker’, referring to the manner in which bearded sakis have sometimes been observed drinking by scooping water in the hollow of their hand and bringing it to their mouth. This was once thought to be an attempt to keep their magnificent beards dry (5).

Endemic to Brazil, the bearded saki occurs only in a small area of the eastern Amazon basin (1) (7), situated south of the lower Rio Amazonas and east of the Rio Tocantins (1).

Like all New World primates, the bearded saki lives almost exclusively in trees (2). It is found in tropical rainforest, often near streams and rivers (4) (7), and preferably in areas that are not flooded and are undisturbed (7).

Bearded sakis specialise in eating the young seeds from inside unripe fruits (2) (8). Their robust canines (8), along with the other upper teeth that jut forward over the lower teeth like a macaw’s beak, are perfect for cracking open the hard shells of some fruits and nuts, enabling them to reach the soft kernels within (4). Their remarkably strong jaws and teeth are capable of breaking open fruits that humans would be unable to achieve without the aid of a hammer (4). Bearded sakis supplement this diet of seeds and fruits with arthropods, including spiders and insects (9), and, unusually, soil. The habit of eating soil, also known as geophagy, may be done for a number of reasons, such as for minerals, to absorb toxins, or to alleviate gastrointestinal upsets (10).

Seeking out trees with the best seeds and fruits is a time consuming activity for the bearded saki (6), undertaken in groups of around 30 individuals (4). The gestation period in this monkey lasts for five months, with just a single young born at a time. The bearded saki becomes sexually mature at four years of age and can live for more than 18 years (4).

Situated within one of the most densely inhabited parts of the Brazilian Amazon (7), the small range of the bearded saki has been subject to logging and other disturbances such as the construction of a hydroelectric plant and major highways (4) (7). In some areas, the effects of intense habitat disturbance are exacerbated by hunting pressure (11); bearded sakis are hunted for bushmeat (12), and their tails are reportedly used as dusters (7). This perilous combination of habitat destruction and hunting, along with the bearded saki’s specialised diet and preference for undisturbed forest (7), has led some to regard the bearded saki as the most endangered primate in the Amazon (4).

The bearded saki is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning that any international trade in this species should be carefully monitored (3). However, to ensure the future survival of this highly threatened primate, adequately protected reserves and a captive breeding programme are said to be urgently required (7).

For further information on conservation in the Amazon see:

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  1. IUCN Red List (May, 2014)