INTRA- AND INTERINDIVIDUAL VARIATION IN THE CONTACT CALLS OF SPECTACLED PARROTLETS (FORPUS CONSPICILLATUS)

The ability to discriminate individuals or different social classes of individuals is important for the evolution of social behaviour. In animal societies with ample social relationships selection will often favour the capacity to signal and perceive the identity and the membership to a certain social class. Spectacled parrotlets (Forpus conspicillatus, Psittacidae, Psittaciformes) live in a complex system of social relationships throughout their lives and are able to recognize their mates and their siblings on the basis of their contact calls. Here we attempt to identify the acoustic parameters that might be used in individual recognition and recognition of social categories. Therefore we analysed recordings of contact calls with reference to the variation of certain acoustical parameters. There was significant interindividual variation in the peak frequency, maximum frequency, duration, energy, bandwidth and minimum frequency in the contact calls of spectacled parrotlets. Discriminant function analysis has shown individual and social subunit specific calls but also that individuals of different social classes share some calls. From our results we hypothesize that spectacled parrotlets could use at least six acoustical cues in their contact calls that might encode information about the individual, the age class, the pair, the pairing status and the family.