Up-scaling local-habitat models for large-scale conservation: Assessing suitable areas for the brown bear comeback in Europe

Aim: Large carnivore populations in Europe are expanding into new areas. This generates opportunities to improve their conservation status, but also creates a need to address new conflicts with humans. Species management units are constrained by administrative boundaries, but effective conservation and conflict management require a continental-scale perspective on the opportunities and limitations for expanding populations. We assessed the conservation applicability and the uncertainties of transferring and up-scaling local habitat suitability models from multiple populations in support of large-scale, transboundary species conservation. Location: Europe. Methods: We evaluated the accuracy of local population models to predict European brown bear (Ursus arctos) distribution patterns in other populations and at the continental scale. We also assessed the benefits of combining predictions from multiple local population models, and we evaluated the limitations of transferring models among populations and environmental settings. Last, we estimated the availability of unoccupied suitable habitats in Europe for colonization by expanding populations. Results: We found that integrating habitat predictions from multiple populations outperformed predictions from most individual populations. Results showed that about 37% of potentially suitable brown bear habitat in Europe remains unoccupied. As a synthesis of our results, we provide a set of predictive maps for the expansion of brown bears at the continental scale, including predictions from individual habitat models and a multimodel predictive map. Main conclusions: We show that integrating habitat models from multiple populations provides richer and more reliable information on the distribution of suitable habitats in data deficient areas. This integration yields more reliable predictions compared to those based on individual populations and has important implications to manage species expansions and the associated conflicts. We also identified major limitations in transferring predictions among habitats; therefore, it is critical to enhance the reproducibility of habitat suitability models to apply local-scale habitat studies to broader-scale conservation practice.