Population density and habitat preferences in a Tawny Owl Strix aluco population in floodplain forests in Eastern Austria
Nagl Christina, University of Vienna (AT)
Owls are among the most secretive birds on Earth. Hence, few data about these species are available, especially from the highly dynamic and often inaccessible floodplain forest ecosystems. In this study we assessed population density and habitat preferences of Tawny Owls Strix aluco in lowland floodplain forests along Danube and Morava River in Eastern Austria. Owls were surveyed using playbacks. To avoid double counting we recorded their calls, which allow individual recognition of the majority of birds. Following 50 river kilometres and covering an area of more than 10,600 ha altogether, we recorded and identified 60 individual male Tawny Owls. The high territory densities (5.0-7.8 territories/10 km2) indicate a high habitat quality of floodplain forests for this species. While our habitat models indicate no significant difference of the occurrence probability of Tawny Owls between hardwood and softwood floodplain forests and no avoidance of Eagle Owl Bubo bubo territories, old trees (>80 years), a certain amount of openland and high amounts of standing deadwood did positively affect the species' occurrence. Our study provides evidence that the heterogeneous forest landscapes with patches of old forest stands characterized by a high density of dead trees, as found in the last remaining extensive floodplain landscapes along Danube and Morava River in Eastern Austria, represent high quality habitats for Tawny Owls.