Since 2015, barriers have been erected at several national borders in Europe to restrict human migration, with alternating reels of razor wire and panel fencing at the border between Slovenia and Croatia. As an indirect consequence of border barriers, animal movement is restricted and deaths due to entanglement in barriers have increased. Large mammals are the most sensitive to barriers, among them especially large carnivores (brown bear (Ursus arctos), wolf (Canis lupus) and Eurasian lynx (Lynx lynx)). During the field work of inventorying the signs of large mammals' presence by winter tracking and photo-trapping in the border area, we have found a concentration of large mammals in the central part of the large carnivores' range. The photo-trapping was particularly focused on Čičarija, where we showed the importance of passages for game in the barriers by comparing the presence of cameras along the razor wire and the opening in it. In areas where a barrier was present, we recorded instances of crossings and found that the razor wire posed less of a crossing problem for smaller species of large herbivores, while no instances of large mammal crossings were recorded at the panel fence.
Based on literature data, we prepared cost layers for large carnivores in QGIS and produced border connectivity models for them in Circuitscape under different scenarios of barrier presence at the southern border between Slovenia and Croatia. We found that, especially in the case of a higher barrier presence with panel fencing, the latter would pose a problem for the passage of large carnivores and consequently reduce the connectivity of parts of their populations.
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