Pithecia monachus
monk saki

Also known as Pithecia hirsuta, Pithecia monachus can be found in northwestern Brazil, Colombia, Ecuador and Peru (Nowak, 1999). Members of this species occur in the Colombian trapezius north of the Amazon, and extend from north of the Putumayo River to the southern bank of the Yari, Caqueta and Orinoco rivers. The range of Pithecia monachus is limited to the upper elevations of well-developed rain forests of these regions (Hernandez-Camacho and Cooper, 1976). (Hernandez-Camacho and Cooper, 1976; Nowak, 1999)

Arboreal, high canopy dwellers. They are very nervous around humans and disturbance, thus very little data has surfaced on the lifestyle of P. monacha. However, scientists agree that the tallest trees available (from 10-35 meters tall) are the habitat of choice for these animals, and in most instances they are the sole primate inhabiting this niche. (Moynihan, 1976)

Sakis are characterized by their small size of 30-50 cm and very heavy, thick and nonprehensile tail which adds 25-55 cm to their body length (Nowak, 1999). The face of the monk saki is partly bald but bearded with a hood of curly black hair covering the forehead. The nostrils are laterally positioned on the face (Flannery 2004). Sakis are generally black, but their hands and feet are light in color.

The skull morphology is distinctive: the orbits are separated from the brain case by a frontal depression. The incisors are forward-facing, long canines are present and used to break the hard skin of fruits. They have quadritubercular molars with deep basins (Seth & Seth, 1986).

The hands are similar to those of Aloutta spp. in that they exhibit a split between the second and third digits (Moynihan, 1976). Each digit has a nail, and the front limbs are shaped for gripping branches after a leap. The hind legs are modified for fast and far leaping. Vision is stereoscopic for an arboreal habitat. (Flannery, 2004; Moynihan, 1976; Nowak, 1999; Seth and Seth, 1986)

All species of Pithecia are diurnal. The monk sakis are quadrupedal leapers. They are skittish and shy. Family groups are nuclear families consisting of a monogamous pair with its offspring. These families raise offspring in defended territories, similar to gibbons in the genus Hylobates. A peculiar behavior is observed at night when several families sleep in the same tree. The adults recognize their mate by highly specialized vocalizations; acoustic signals including squeaks, whistles and trills are used for low intensity aggression. Barks and grunts constitute a higher level of aggression, and finally, roars are the most extreme aggressive vocalizations. The monk sakis practice extensive allogrooming as a general social behavior which is nonsexual in orientation or motivation. (Hernandez-Camacho and Cooper, 1976; Moynihan, 1976)

Home Range

Home range differs by gender: males travel in a 50 ha area, while the females utilze only 33.5 ha. (Dunbar, 1988)

The diet of the monk saki is frugivorous but also includes seeds, nuts, and some insect material. They have also been documented to prey on bats (Moynihan, 1976; Hershkovitz, 1977). They use their large canines to break their food before ingesting it. The monk saki's high quality diet restricts their range in that they must be able to sequester enough high-protein food for their immediate family group (Terborgh, 1983). (Hershkovitz, 1981; Moynihan, 1976; Terborgh, 1983)

This species is rated "Least Concern" by the IUCN, as there are still believed to be substantial populuations in the upper Amazon basin. It is listed on Appendix II of CITES, so there are restrictions on international trade of the animals or their parts.

Very little research has been done on Pithecia monacha, perhaps for two reasons: they do not survive well in captivity, and are very difficult to view in the wild, due to shyness and a very high habitat.