There is some first evidence that nonhuman animals as dolphins and parrotlets use referential signals for different social companions and thus have mental representations of their conspecifics. In a former study we found out that spectacled parrotlets (Forpus conspicillatus) use specific contact calls to refer to their family members and thus label their pair mates and their young. In the present study we wanted to know whether the labels parents give to their young were also used by other members of their group. We recorded contact calls of the parents and four group members that were directed to four juveniles at the age of three to seven month. Recordings were made when an adult and a juvenile were separated from the group and interacting with one another during spatial but not visual separation. Discriminant function analysis of the acoustic cues of calls revealed high similarities between the calls that were directed to the young by their parents and calls that were directed to the young by the group members. Although very similar there was enough difference between the calls of parrotlets recorded to allow individual recognition of the caller. Only the calls used for the youngest bird were more different. We conclude that the group members take over the same labels that parent use for their offspring. This process will occur around three month after fledging when the young were independent from their parents and recently integrated into the group.
Abstract: