Brown Bears in Slovenia: Identifying Locations for Construction of Wildlife Bridges Across Highways

Slovenia lies on the north-westernmost edge of continuous Dinaric-Eastern Alps population of the Eurasian brown bear (Ursus arctos). It has a stable population of 320-400 bears, occupying a range of about 5000 km², predominantly in the most forested southern regions along the state border to Croatia. The alpine and pre-alpine regions of western Slovenia represent an essential link for the expansion of brown bears from Dinaric mountains into the Alps. With recent construction of the highway network in these regions, new barriers through the potential bear corridors have been introduced threatening connectivity of large patches of core habitat. The paper deals with the results of the Geographic Information Systems (GIS) and artificial intelligence based modeling, aimed to identify the most suitable locations for the construction of wildlife bridges/underpasses, enabling safer crossing of the highway by the bears. An expert system for classifying the habitat suitability for brown bear was developed. The knowledge base for the expert system, induced by a machine learning method from recorded bear sightings, was linked to the GIS thematic layers. The main factors considered by the expert system were: the land use types (rendered by the CORINE Land Cover database), other human impacts and the topography. The expert system was implemented in GIS, thus enabling the mapping of suitable brown bear habitats. Broad potential dispersal corridors were identified, taking into account actual land cover between the patches of suitable habitat. Thus identified most probable locations of highway crossings by the brown bears were taken as the most convenient locations for the construction of the wildlife bridges/underpasses.