Changes in experimental conditions alter anti-predator vigilance and sequence predictability in captive marmosets

Anti-predator vigilance and its sequence predictability in captive adult male black tufted-ear marmosets (Callithrix penicillata) was analyzed under three experimental conditions: (1) four novel (maze) environment habituation trials; (2) six taxidermized (cat) predator confrontation trials in the same maze environment; and (3) four additional maze-only trials, in the absence of the cat stimulus. Significant quantitative and qualitative differences (aerial vs. terrestrial) were observed in scan and glance behaviors within and between the three experimental conditions. Furthermore, inter-scan bout sequence significantly deviated from randomness during the initial maze habituation and predator confrontation trials, as well as during all predator removal trials. This parameter, however, followed a random pattern during the course of the remaining sessions. Therefore, vigilance in marmosets seems to be an important and highly organized component of this species' anti-predation repertoire, inasmuch as it occurs at high rates, alters according to specific environmental cues and has a subtle differential adaptive response after repeated trials.