On BCI, it is estimated that male spider monkeys range over an area of 300 or more hectares in search of food while females range over a somewhat smaller area, estimated at 200 or more hectares. Like howlers, spider monkeys eat a wide array of different plant species, consuming foods from over 125 different plant species per year. There is intense bonding between males of a spider monkey troop and if you see a group of spider monkeys in the forest, you may discover that all of them are males. Like human infants, young spider monkeys have a very long period of maternal dependence. On BCI, spider monkey infants, in contrast to the brilliant red adults, are black when born and tend to have large naked pink areas around the eyes.
Infants remain tiny and fairly helpless until they are almost a year old.
They are carried by the mother until more than two years of age and continue to associate and travel with the mother until they are at least 3.5 years old. Spider monkeys have relatively large brains for their body size and it would appear that as they mature, they need time to learn the types and locations of a large number of different fruit species in the forest as well as other behaviors critical for survival. The long period of maternal dependence should permit each young monkey to mature sufficiently to master all of the information that seems to be required to specialize successfully as an independent adult on a diet composed almost exclusively of ripe fruits.