Ateles belzebuth
white-bellied spider monkey

White-bellied spider monkeys, Ateles belzebuth, are found in the northeastern portion of the Amazon in South America. Colombia, Venezuela, Peru, Ecuador, and Brazil are all countries that this species is known to inhabit. (Cant, et al., 2003; Eisenberg, 1989; Emmons, 1997)

White-bellied spider monkeys are found in the rainforests of northern South America. They live in the upper levels of tall forests and can be found at a maximum elevation of 1,800 m. (Emmons, 1997)

A. belzebuth has a similar shape to A. paniscus, with arms and legs longer than the body. These monkeys also have a prehensile tail. A. belzebuth differs from A. paniscus in that it has a pale or white triangular patch on the forehead. Another distinguishing characteristic of this species is that the dorsal side of the animal can range from black to dark or light brown whereas the ventral side is pale brown to white. These animals have bright whitish eyeshine. The prehensile tail of these monkeys is used for locomotion and foraging, and can range from 61 to 88 cm in length. The legs of this species are long and slender. Weight ranges from 5.9 to 10.4 kg. Male body length that ranges from 42 to 50 cm, whereas females can be anywhere from 34 to 59 cm. (Emmons, 1997; Schafer-Witt and Welker, 1990)

A. belzebuth live in groups in which there are three times as many females as there are males. The total number of individuals in a group ranges from 20 to 40. Mating occurs randomly, and females will mate with one or several males in one day. The reproduction of this species is similar to that of other members of Atelinae especially the A. geoffroyi and A. paniscus. Variation occurs with the species. (Emmons, 1997; Schafer-Witt and Welker, 1990)

Females give birth to one offspring every 2 to 4 years. Their estrus cycle is 24 to 27 days in length, and gestation length is between 210 and 225 days. (Emmons, 1997; Rudolph, 2002; Schafer-Witt and Welker, 1990)

Copulations are initiated by females, who approach males. Like other species of Ateles, it is likely that this pattern of initiating copulation leads to high levels of female mate choice, and reduces aggression between males. (Robinson and Janson, 1986)

Although not reported for this species, males in other species of spider monkeys which have been studied ejaculate after one mount and one series of thrusts. (Hrdy and Whitten, 1987)

The timing of sexual maturity in A. belzebuth is not known, but is probably similar to other species in the genus. In these species, sexual maturity of both males and females occurs sometime between 4 and 5.5 years of age. (Robinson and Janson, 1986)

The exact time of weaning in this species is not known, but is similar to that of other spider monkeys. At 12 to 15 months the infants are weaned, but independence is not achieved until at least 17 months of age. As in most primates, females provide the bulk of parental care. Male parental behavior for this species has not been mentioned. (Robinson and Janson, 1986)

The lifespan of this species is unknown, but is similar to other spider monkeys. In captivity, the lifespan is 30 to 40 years for other species of spider monkeys.

A. belzebuth is highly social, and is active during the day. Groups of these animals range from 20 to 40 members, but they also split into smaller subgroups during the day to forage. This type of social organization is called fission-fusion sociality. Although most animals live within a social group, solitary individuals are reported to be common.

These monkeys move through the upper part of the canopy using their prehensile tails and limbs. Brachiation, arm swinging with the body below the branches, is an important mode of locomotion for these species. (Bramblett, 2001; Cant, et al., 2003; Emmons, 1997; Robinson and Janson, 1986; Rudolph, 2002; Schafer-Witt and Welker, 1990)

Species in the genus Ateles do not typically show a great deal of aggression to other members of the social group. However, in spite of this relatively non-aggressive existence, both males and females show clear dominance heirarchies. There does not appear to be a simple relationship between dominance ranking and reproductive success among males. Also, relationships between different groups of these primates are reported to be marked by intollerance. (Robinson and Janson, 1986)

Males tend to show more affiliative behaviors than do females within the genus Ateles. They are more affiliate both to other males and to females within their groups. Females often visit other groups while carrying newborn offspring, and young females are know to migrate into new groups permanently. (Robinson and Janson, 1986)

The average home area used by a single group encompasses 150 to 250 ha. An overlapping of 1.5 ha will occur between groups. (Eisenberg, 1989; Emmons, 1997; Robinson and Janson, 1986)

A. belzebuth communicates with long calls to identify other members of the group and their territory. It also uses barks and screams which are probably used to signal danger. Tactile communication, in the form of both aggression and affiliative touching (like grooming) also occurs. Visual signals, such as approaching a conspecific, provide important communication about intentions, willingness to mate, and possibly dominance position. (Broekema, 2002; Emmons, 1997; Hrdy and Whitten, 1987; Robinson and Janson, 1986)

The diet of A. belzebuth consists mainly of fruits, but these primates will also eat seeds, leaves, and sometimes dead wood. The amount of time an animal spends about 22% if its time foraging versus 15% of its time moving. Of the time these animals spend feeding, about 83% of the time is spent obtaining ripe fruits. About 7% of their foarging time is spent eating leaves, and the remaining 10% is used getting other food items. (Emmons, 1997; Robinson and Janson, 1986)

Most feeding occurs during the early morning and late afternoon and occasionally the animal is known to feed during nights with a bright moon. (Emmons, 1997)

Possible predators of this species may include felids or birds of prey such as eagles. (Broekema, 2002)

Although it occurs with only a few species of seeds, A. belzebuth is known to occasionally increase the rate of germination of some plants. Because these animals eat mostly fruits that are rich in lipids, they may be the best dispersers for fruits that fall into this category. (Stevenson, et al., 2001)

There are no known benefits this species provides to humans.

There are no known adverse affects of A. belzebuth on humans.

A. belzebuth is considered endangered by IUCN, and is listed on CITES Appendix I. The major threats to this species are loss of habitat through deforestation and hunting. National parks in Colombia aid to the conservation of A. belzebuth as well as specific protected habitats and isolation of the habitats from development.