Intra- and interindividual variation in the contact calls of spectacled parrotlets (Forpus conspicillatus)

The ability to discriminate individuals or different social classes of indi viduals is important for the evolution of social behaviour. In animal socie ties with ample social relationships selection will often favour the capaci ty to signal and perceive the identity and the membership to a certain soci al class. Spectacled parrotlets (Forpus conspicillatus, Psittacidae, Psitta ciformes) live in a complex system of social relationships throughout their lives and are able to recognize their mates and their siblings on the basi s of their contact calls. Here we attempt to identify the acoustic paramete rs that might be used in individual recognition and recognition of social c ategories. Therefore we analysed recordings of contact calls with reference to the variation of certain acoustical parameters. There was significant i nterindividual variation in the peak frequency, maximum frequency, duration , energy, bandwidth and minimum frequency in the contact calls of spectacle d parrotlets. Discriminant function analysis has shown individual and socia l subunit specific calls but also that individuals of different social clas ses share some calls. From our results we hypothesize that spectacled parro tlets could use at least six acoustical cues in their contact calls that mi ght encode information about the individual, the age class, the pair, the p airing status and the family.