Turnover of territorial Scops Owls Otus scops as estimated by spectrographic analyses of male hoots

In this study we assessed territory turnover of the European Scops Owl Otus scops, a migratory nocturnal raptor, using sonagrams of hoots recorded in the same territories in the 1993 and 1994 breeding seasons. Three structura l parameters of the hoot (duration, inter-note interval and frequency) vari ed considerably, and a Discriminant Function Analysis classified > 90% of i ndividual calls correctly. In order to investigate yearly turnover and site -fidelity of male Scops Owls, the discriminant functions derived from the h oot sample recorded in 1993 were used to classify hoots of individuals reco rded in the same territories in 1994. Apparently, turn-over rate of territo ry owners was high and rapid, because 55-78% of territories censused in 199 3 were defended by a different male in 1994. The fast decline of our Scops Owl population, probably due to winter mortality, could be responsible for such a high turnover of territorial owners.