Individual identity coding depends on call type in the South Polar skua Catharacta maccormicki

In colonial birds, acoustic communication is essential for mate recognition . The South Polar skua (Catharacta maccormicki) lives in loose colonies and is highly territorial for feeding and breeding. We studied the potential o f individual identity coding in the three main calls of the South Polar sku a repertoire: the courtship, the contact and the alarm calls. We investigat ed parameters in both temporal and frequencial domains, i.e. amplitude modu lation, frequency modulation and power spectrum density. For each parameter , the intra- and inter-individual variabilities were calculated. The ratio between these values represents the potential of individuality coding (PIC) of the considered feature. Low values of PICs for amplitude and frequency modulations show that both parameters may not be used for individual recogn ition. In contrast, high values of PIC for the power spectrum density indic ate that the energy distribution among the frequency spectrum is likely to be an individual marker. PIC also varies according to the call type. Both c ourtship and contact calls have a higher potentiality of individual identit y coding than the alarm call. The two former calls may allow individual rec ognition whereas the latter may not, and this last result can be extrapolat ed to many other species.