Early Movements of Eurasian Scops Owl Otus scops Fledglings and the Response of Territorial Neighbours

The post-fledging dependence period is a poorly known life stage of birds. In particular, knowledge of the interactions of fledged birds with unrelated conspecifics is scarce. In territorial species, entering a foreign territory poses risks to a juvenile bird associated with the likely aggressive response of the territory owner. In this work, I explored the early movements of fledged Eurasian Scops Owls in a densely-packed neighbourhood characterized by small and contiguous territories. To detect, identify, and track juvenile owls, I combined visual monitoring and spectrographic analysis of their vocalisations, which exhibited individually distinctive features. Juvenile owls entered foreign territories about five days after fledging and came in contact with neighbouring adults. The neighbouring adults never attacked the juveniles. Instead, they attacked the adults that were escorting and feeding those juveniles. During those interactions, they called at an acoustic frequency lower than that of the calls they gave on other occasions. Thus, territorial Scops Owls perceived juveniles differently from adults. The results emphasize an overlooked aspect of the early life of Scops Owls, when repeated interactions with other individuals can potentially influence their movement and possibly dispersal. Furthermore, the adults that attend a brood are likely to incur a cost of aggregation, in terms of the risk of being injured during conflicts with their neighbours.