the Geoffroy's spider monkey uses suspensory locomotion less frequently than other spider monkey species. The most common method used by spider monkeys to cross between trees is "bridging", in which the monkey grasps for a branch from the new tree and pulls it towards itself so it can climb onto it. Airborne leaps are used when necessary, and certain populations of Geoffroy's spider monkey, especially in Panama, are known to leap between trees more frequently than other populations. When not moving, Geoffroy's spider monkey uses not only supported postures, such as sitting or standing, but also suspended postures in which it hangs from a branch. Suspended postures always include support from the tail, and sometimes the monkey hangs by its tail alone. Other times it hangs by the tail and by one or more limbs simultaneously. Studies have indicated at least some Geoffroy's spider monkey populations use suspended postures less frequently when feeding than other spider monkey species. Communication and intelligence Sounds produced by Geoffroy's spider monkey include barks, whinnies, squeals, squeaks and screams. Barks are typically alarm calls. Whinnies and screams can be used as distress calls, and are also made at dawn and at dusk. Each monkey makes a unique sound, which may allow monkeys to recognize each other through vocal communication alone. Several researchers have investigated the use of whinnies, which consist of between two and twelve quick increases and decreases in pitch, in more detail. This research has indicated one additional purpose of whinnies is to call other group members to a food source. 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. Geoffroy's spider monkey uses several forms of nonvocal communication. A curled tail or arched back can be used as a threat display towards other spider monkeys. A head shake is used either as a threat or an invitation to play. Shaking branches or swaying arms is used as a warning of danger to the group. Although they do not use tools, spider monkeys, including Geoffroy's spider monkey, are regarded as intelligent primates. A study performed in 2007 concluded they were the third most intelligent nonhuman primate, behind only orangutans and chimpanzees, and ahead of gorillas and all other monkeys. This mental capacity may be an adaptation to spider monkeys' frugivorous diets, which require