The black bearded saki (Chiropotes satanas) is a species of New World monkey, native to the Amazon rainforest of South America, specifically to an area of north-eastern Brazil. It is one of five species of bearded saki. Bearded sakis are medium-sized (50 cm), mostly frugivorous primates, specialised in seed predation. The genus name Chiropotes means "hand-drinker" as they have been observed using their hands as ladles for scooping water into their mouths. This behavior is thought to be a way of maintaining and protecting their characteristic beards. The black bearded sakis habitat has undergone heavy habitat fragmentation, making the future conservation status of the species uncertain.
Distribution and habitat
Black bearded sakis are endemic to the far eastern Amazon in Brazil, in a range restricted to a relatively small region from the Tocantins River in Pará east to around the Grajaú River in Maranhão (similar to the range of the equally threatened Kaapori capuchin). The natural home range of bearded sakis can vary from 200 to 250 hectares. It is the only Amazonian pitheciid found east of the Tocantins River. Studies show that bearded sakis can adapt to a reduction in their habitat.
Anatomy and morphology
Black bearded sakis can be identified by their thick black hair, distinctive beard that shapes the face, and a bushy fox-like tail. The tail is non-prehensible and they use quadrupedal movement for locomotion. Black bearded sakis have some yellowish-brown highlights around the back and shoulders and can weight from 2 kg to 4 kg. Males are slightly larger than females and also have a bulging forehead. Formerly the red-backed, brown-backed and Uta Hick's bearded sakis, the other member of the genus Chiropotes, were classified as subspecies or taxonomically insignificant variations of the same species called the bearded saki, but based on pelage differences and molecular analysis it has been recommended to treat them as separate species. The black bearded saki is the only dark-nosed species of bearded saki with a blackish back, though some females and juveniles have a paler, brownish back. The teeth have evolved for seed predation: these dental adaptations allow then to crack and access seeds in extremely hard pods. They open hard-shelled fruits in a specialized, efficient process using their teeth.
Behavior
Diet
Black bearded sakis are highly frugivorous, specialized in seed predation as 90% of their diet comes from fruits and seeds. Black bearded sakis feed mostly on plants of the families Sapotaceae, Lecythidaceae, and Chrysobalanaceae, but they are known to feed on more than 100 species and are able to adapt their diets. They complement their diets with fleshy fruits and small insects. Black bearded sakis use their strong canine teeth to crack open hard shells of fruits and nuts, enabling them to access the unripe seeds inside the fruits.
Social behavior
They are social animals, commonly grooming and playing with one another, even with those of other primate species. Black bearded sakis can be found in troops of 20 to 30 individuals. Individuals of a troop will separate and rejoin throughout the day, have large home ranges, and travel long distances daily.
Movement
Black bearded sakis spend most of their time resting, traveling and eating. Black bearded sakis use mostly quadrupedal movement to move in the canopy of trees. As infants the monkeys can be seen using their tail to grasp things, but lose the ability as they mature.
Reproduction
Bearded sakis have a gestation period of 5 months and produce one young at a time. They become sexually mature at 4 years old and have an expected lifespan of 18 years. Black bearded sakis give birth to offspring every 2 years.
Conservation
Black bearded sakis are a critically endangered species. Just over the last few decades urbanization in the Brazilian Amazon has brought with it highways, agriculture, and dams, creating an influx of habitat fragmentation, habitat destruction and poaching pressure. Habitat fragmentation is rising as secondary roads increase and people move into uninhabited areas of the Amazon rainforest. Along with an influx of people the amount of agriculture required to support the area increases, augmenting the pressure for deforestation.