are extremely conscious and alert to his location, and they all observe his reactions. If the alpha reacts with intense fear or panic or if he pays close attention to something, all members of the troop react similarly. The presence of adult males seems to lend psychological support to the smaller adult females. Defler noticed that more timid females often became quite aggressive towards him when a male appeared on the scene, although the females often needed to press up against the flank of the male for reassurance. Communication Vocalizations are variable, and some are listed as follows: (1) ua - a soft bark given repeatedly and used by all members of the group when danger is perceived; (2) ya - excited animals around the alpha, towards alpha and towards perceived danger; (3) eh-eh - threat towards potential danger, but especially adult females; accompanied with open mouth showing teeth (OMT); (4) squeaky hinge - threat given especially by young animals; (5) squeal - conflict within the group during a fight; (6) whistle - conflict in the group of a young animal; (7) ahr - a lost animal; others answer this call, apparently to direct it back to the group; (8) uh!uh!uh! - a common vocalization during feeding which may allow contact to be maintained and show general contentment; (9) uch!uch! - an animal trying to keep up with the group; (10) warble - young animals establishing contact or coming close to an adult; (11) purr - close and pacific contact; (12) chirriar - pacific interaction of young ones during play. Perhaps the most important display is the behavior of breaking branches, which all members of the group carry out. Even infants break small branches (or twigs), letting them fall to the soil, but the most spectacular is the alpha male who chooses large, dry branches which he hits with his hands and feet in spectacular jumps, so that they fall. Usually such branches make a tremendous sound as they fall through the other branches, and the members of the group become very excited and chatter loudly. This behavior is quite commonly discharged towards an observer when the animals have lost their fear. Tool use Trinidad white-fronted capuchins have been observed using leaves as cups to drink water from tree cavities. The leaves used were modified before by changing the shape of the leaf. The leaves are discarded after one use,