Conspecific vocalisations modulate the circadian activity rhythm of marmosets

Conspecific vocalisations have an important ecological role for marmosets and likely modulate the circadian timing system. However, the effect of this specific cue on circadian activity rhythm (CAR) has not been evaluated. To analyse the synchroniser effect of conspecific vocalisations on CAR in marmosets, the motor activity of five isolated adult males was continuously recorded in rooms with constant dim light (~2 lx) and attenuated sound. All animals presented positive masking, four presented relative coordination and three presented temporary entrainment associated with the daily pattern of vocalisations from animals kept outdoors, similarly to previous studies that assessed social cues. Furthermore, most animals displayed a shortened circadian period in response to conspecific vocalisation pulses that were reproduced daily for 30 days under total darkness. This is evidence that a non-photic cue with ecological significance can modulate the CAR, reinforcing the role of conspecific vocalisation as an im...