Mag. Markus Uitz

budj@gmx.at

PDF im Hochschulschriften-Service der Universit├Ąt Wien


Potential distribution of Ural Owl Strix uralensis macroura in Central and South-East Europe.

The Ural Owl populates large areas of northern Europe, Siberia and Japan. A relict population, the subspecies Strix uralensis macroura, can be found in Central and Southeast Europe. It occupies open woodland mainly in mountainous regions, although critical studies on habitat requirements do not suggest that altitude itself is of special importance to the species. The quality of the woodland seems to be more relevant. Only few studies concerning the Ural Owl in its natural habitat have been published so far, and accordingly information about factors that govern its distribution are rare. This study aims at (i) delineating the current potential distribution of the species on a large scale and (ii) identifying the environmental factors that can best explain the current distribution pattern by means of ecological niche modeling and geographic information systems (GIS). A set of climatic variables, land-cover data, elevation and a recently published layer compiling data of the human footprint was used to compute a species distribution model with the help of MAXENT, a machine-learning algorithm developed for modeling with species presence-only data. The model was projected to the study area to produce a map of the current potential distribution. Areas with medium and high suitability mainly concentrate on mountainous regions. The results further show that habitat elevation had a similar effect on the prediction as compared to human footprint. Consequently, the concentration of the Ural Owls distribution in mountainous regions rather appears to be an artifact of the lower extent of human activities in such areas.