Black-bearded Saki (Chiropotes satanas)
The average body mass for the black-bearded saki ranges from 2.7 to 3.2 kilograms (van Roosmalen et al., 1981). This species has broad canines along with strong jaw muscles to assist in the eating of fruit with a tough pericarp. The scrotum of the male is pink in color. The male does not possess a baculum like other primate species (Hershkovitz, 1993). The penis of the male has large hooked spines (Hershkovitz, 1993). There is little sexual dimorphism of the canine teeth (Kay et al., 1988). The premolars of this species have crenulated occlusal surfaces (Kinzey, 1992). This species has a distinct beard and temporal swellings (van Roosmalen et al., 1981). The tail of the adult black-bearded saki is not prehensile, but the infant's tail is prehensile for the first two months of life (van Roosmalen et al., 1988). The subspecies Chiropotes satanas satanas has a pelage color which is black with a black to brown back and shoulders (van Roosmalen et al., 1981). The subspecies Chiropotes satanas chiropotes has a pelage color which is black with the area from the shoulders to the base of the tail being yellowish-brown to ochraceous (van Roosmalen et al., 1981).
The black-bearded saki is found in the countries of Brazil, French Guinana, Guyana, Suriname, and Venezuela. In Brazil this species is found in terra firma forests and occasionally in regenerating forests, but this species is never found far from tall forests (Johns and Ayers, 1987). This species cannot survive in areas of a high level of agricultural encroachment or in areas where there is moderate to high levels of logging (Johns and Ayers, 1987). In Suriname this species lives in the high forest and the mountain savanna forest in the middle and upper levels (Fleagle and Meldrum, 1988).
The black-bearded saki is primarily a sclerocarpic frugivore (van Roosmalen et al., 1988). This species feeds upon 85 different plant species, with immature seeds comprising a majority of the fruit species consumed, with ripe fruit also being of importance (van Roosmalen et al., 1988). In Suriname it was found that 80% of the plant species were trees, 18.8% were lianas or vines, and 1.2% were epiphytes (van Roosmalen et al., 1988). In Suriname favorite fruit species come from the family Lecythidaceae and include species Eschweilera and Lecythis davisii (van Roosmalen et al., 1988). The black-bearded saki uses its incisors to open the operculum of hard-coat seeds (van Roosmalen et al., 1988). With the more difficult species such asHymenaea courbaril and Lucania majuscula, the wedge-shaped canines are used to open up the seed coat to gain access to the seeds (van Roosmalen et al., 1988). The seeds consumed are generally younger and softer before they develop secondary compounds that may be fatal to an individual (van Roosmalen et al., 1988). Mature seeds have been found to have been consumed from the species Pradosia caracasana and Chrysophyllum lucentifolium (Norconk et al., 1997). In the Amazon, this species is one of the main predators of seeds from the family Sapotaceae (Spironello, 1998). van Roosmalen et al. (1988) suggest that predation upon young seeds evolved in the black-bearded saki as a way to survive in the forest by not competing with other frugivorous species and filling an unoccupied niche. This species to a lesser extent forages for flowers, leaves, and insects. The black-bearded saki forages on unripe fruit that other primates would only eat when ripe (Kinzey and Norconk, 1990). Most of the insects this species consumes are soft-bodied (Kinzey, 1997). Frazao (1991) found this species consumed insects from the orders Coleoptera, Hymenoptera, and Lepidoptera, with Lepidoptera being the order from which the most species of insects were eaten. Mittermeier et al. (1983) found this species consumes insects from the orders Coleoptera, Diptera, Hymenoptera, Hemiptera, Lepidoptera, Neuroptera, and Orthoptera and from the suborders Heteroptera and Homoptera, with the most popular insects consumed being larval Coleoptera and Diptera. Ayres and Nessimian (1982) found that the black-bearded saki consumes insects from the orders Lepidoptera, Coleoptera, Hymenoptera, Diptera, Hemiptera, Ephemenoptera and the suborder Homoptera and the superfamily Mantodea, with the most frequent species coming from larvae of Pyralidae (Lepidoptera) and adult Formicidae (Hymenoptera).
This species lives in large groups that break up when foraging (van Roosmalen et al., 1988). The groups break when arriving to new a new food source, then coming together when moving between food sources (Norconk and Kinzey, 1994). When this species forages it moves rapidly between trees, foraging for a short amount of time in a cluster of trees, but the feeding bouts are described as being intense (van Roosmalen et al., 1988). The groups move so fast during feeding that occasionally an individual is left behind and usually this individual will join up with other species, such as Cebus apella or Saimiri sciureus, and form a mixed-species group (Norconk and Kinzey, 1994). The group size for this species ranges from 8 to 27 individuals (Ayres, 1989). This species never uses the same tree for consecutive nights and sleeps on medium size branches of emergent trees (Kinzey, 1997).
The black saki moves through the forest canopy quadrupedally (Fleagle, 1988). This species uses hindlimb suspension when feeding (Fleagle, 1988). This species also occasionally leaps from a pronograde position and lands on the terminal branch of a neighboring tree (Walker, 1993). When leaping this species first starts to move quadrupedally, then takes-off from a horizontal or angled support, using the momentum gained to assist in the leap (Walker, 1998). Usually this species lands when leaping on all fours (both the hands and feet) (Walker, 1998). Quadrupedal locomotion is the most common (80%) locomotion pattern with leaping (18%) the second most common (Fleagle and Meldrum, 1988). This contrasts with another pithecine, Pithecia pithecia where leaping accounts for 70% of its locomotory behavior (Fleagle and Meldrum, 1988). The tail is either positioned in a loop behind the body or above the head when moving (van Roosmalen et al., 1988). When moving this species uses multiple, small supports and spends most of its time in the main crown and the terminal branches (Walker, 1994). The black-bearded saki occasionally climbs in the head-down posture (van Roosmalen et al., 1981).
The black-bearded saki has a multimale social system, containing unequal numbers of males and females (Kinzey, 1997). Grooming does occur amongst members in the social group (van Roosmalen et al., 1981). The large groups split into smaller groups during the day for foraging (Fleagle, 1988).
high-pitch whistle: This call serves as a contact signal and a more intense version serves as a alarm call (van Roosmalen et al., 1981).This call starts out as a sharp penetrating whistle lasting for one second and then cuts off (van Roosmalen et al., 1981).
weak chirp: This call is heard when eating and also when satisfied (van Roosmalen et al., 1981).
tail-wagging: This serves as a displacement activity and a silent contact signal (van Roosmalen et al., 1981).
The black saki gives birth to a single offspring. The anogenital region of the female, in particular the labia, changes to a bright red when the female is in estrus. The birth season for this species is in December or January (van Roosmalen et al., 1981). This species has a gestation period between 4 or 5 months (van Roosmalen et al., 1981). During estrus the female will present to male, lifting her tail so that the bright red anogenital region shows (van Roosmalen et al., 1981).
After the birth of the young, the mother does not eat the afterbirth like other primate species (van Roosmalen et al., 1981). After nursing the infant will urinate and defecate and the mother will lift the tail of the infant to assist in removing feces (van Roosmalen et al., 1981). The infant moves on its own and stops nursing around three months of age (van Roosmalen et al., 1981).
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Last Updated: May 6, 2007.
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