In the wild monkeys are highly social animals and live in groups called troops. These are composed of a number of females and their young as well as one or more males. Males often leave the troop as they mature and join new troops. Most monkeys are monogamous but some species (such as hamadryas baboons, mandrills and most guenons) allow males to share a troop with several females. Females generally breed at certain times of the year and produce a single young after a gestation period of between five and seven months.
Monkeys use facial expressions, body postures and vocalizations to communicate with each other and convey their emotions. Eye contact is a sign of aggression and threat to nonhuman primates so avoid staring at monkeys. They also use vocalizations to mark their territory and warn other members of a potential fight or other danger. Vocalizations include grunts, squeaks, whistles, howls and barks.
A monkey is a very expensive animal to purchase and maintain. They require a large secure enclosure, frequent outdoor time and an enormous amount of enrichment to prevent boredom and aggression. They are prone to health problems including diabetes and are very difficult to train or tame. They are also likely to attack if they think they are in danger or being threatened and can be very aggressive and biting. Monkeys can live to be 20-40 years old so it is a long commitment to care for an unpredictable, aggressive and potentially dangerous animal.