Geoffroy's spider monkey is
arboreal and
diurnal, and mostly inhabits the upper portion of the forest. It lives in
fission–fusion societies, large groups with a typical 20 to 42 members, which split into smaller subgroups to forage during the day. Subgroups typically number two to six members, and sometimes the subgroups remain separate from the main group even through the night. In addition to walking or running on four limbs and climbing, Geoffroy's spider monkey uses several forms of suspensory locomotion.
Brachiation, or swinging from the arms with assistance from the prehensile tail, is the most common form of suspensory locomotion. Less common forms include swinging while suspended by the tail, and walking on four limbs under a branch. Studies have indicated the Geoffroy's spider monkey uses suspensory locomotion less frequently than other spider monkey species. Other purposes of whinnies suggested by this research have included maintaining vocal contact with other group members while traveling and distinguishing between group members and members of other groups. This mental capacity may be an adaptation to spider monkeys'
frugivorous diets, which require them to be able to identify and memorize many different types of foods and their locations.
Diet Geoffroy's spider monkey eats mostly fruit – preferably ripe and fleshy – and spends 70–80% of its feeding time eating fruit. Leaves make up most of the rest of its diet. Young leaves are especially important to provide the protein that can be lacking in fruit. Other elements of its diet include flowers, bark, insects, honey, seeds and buds. Like other spider monkeys, Geoffroy's spider monkey drinks water from tree holes and
bromeliads in trees, but unlike other spider monkeys, it also drinks from terrestrial water sources.
Eagles and large
snakes are also potential predators. However, predation of Geoffroy's spider monkey has not been observed by researchers.
Reproduction Females bear young every two to four years. Among males, mating is not restricted to only dominant individuals. In one study at
Barro Colorado Island, all males in the group were observed mating at least once over a one-year period. However, dominant males appear to mate more often than low-ranking males. It is unknown whether male dominance is correlated with greater success in fathering offspring. Geoffroy's spider monkeys mate in a sitting position, both facing the same direction, with the male seated behind the female and his arms wrapped around her chest and legs wrapped around her waist. This embrace can last between 8 and 22 minutes. Prior to mating, the male and female both separate themselves from the rest of the group, so they are alone except for any of the female's juvenile offspring. The
gestational period is about 7.5 months, after which a single young is typically born, although twins sometimes occur. The young are dark in color until they begin taking on the adult coloration at the age of five months. They are carried on their mothers' chests for the first month and a half to two months, at which point they can ride on their backs. They nurse until they are about one year old, but begin eating solid foods and moving independently at about three months. Even when they move independently, they cannot always cross gaps in the canopy that adults can manage. To help them, an adult will stretch across the gap, forming a bridge over which the young can cross. Females become sexually mature at about four years, and males at about five years. Upon reaching sexual maturity, females leave their natal group, but males do not. As a result, the males in the groups are typically related, while the females are not. This may help explain why male Geoffroy's spider monkeys form strong bonds. Maximum life span in the wild is unknown. In captivity, Geoffroy's spider monkey can live at least 33 years. == Conservation status ==