Visual monitoring of threatening objects by captive tamarins (Saguinus labiatus)

Captive social groups of red-bellied tamarins (Saguinus labiatus) were observed in the presence of threatening, inanimate objects. The tamarins monitored the stimuli over the course of the 20-minute trials by conducting brief, periodic visual checks of the objects. The average number of checks per subject per trial was stable both across trials and between groups, and individual differences in rates varied relatively little around the group means. These data generate the hypothesis that there is a species-typical execution of vigilance in the presence of mildly threatening objects. This execution takes the form of brief visual inspections of the stimulus, usually by one tamarin at a time, at a fairly consistent rate. The discussion of the data takes place in the context of the behavioral ecology of callitrichid species.