Young Eurasian Scops Owls produce individually distinctive vocalizations

Vocal distinctiveness is expected to occur more often in colonial-breeding species as the parents need to recognize their offspring in a large group of conspecifics. In this study, I examined the food-begging calls of the young of a territorial nocturnal raptor, the Scops Owl, shortly before and after fledging. The calls showed complex spectral structure not described in previous studies. I found a high degree of repeatability in many acoustic features, particularly call duration, spectral centre of gravity, and spectral skewness. Discriminant analysis assigned 52.7% of the calls to the correct individual, and 69.1% when restricting analysis within broods. The calculated information capacity HS was 4.69 bits. Differences in acoustic features between siblings appeared before fledging and could be detected over up to ten days despite temporal variation. The results suggest that the vocalizations of young Scops Owls could potentially act as identity signals. However, the functional significance of acoustic signatures remains unclear. A few hypotheses are discussed. Call distinctiveness could simply reflect the development of vocal individuality typical of the adults; it could help parents recognize their offspring preventing misdirected parental care when breeding density is high; it could mediate preferential feeding; or it could be used by siblings communicating between each other. Further studies are needed to determine whether parents and offspring assess identity signals in vocalizations.