Identifying key denning habitat to conserve brown bear (Ursus arctos) in Croatia

Context. The preservation of denning habitat is paramount to the recovery of threatened bear populations because of the effect that den site disturbance can have on cub mortality. Understanding habitat suitability for denning can allow management efforts to be directed towards the regions where conservation interventions would be most effective. Aim. We sought to identify the environmental and anthropogenic habitat variables associated with the presence of Eurasian brown bear (Ursus arctos) den sites in Croatia. Based on these associations, in order to inform future conservation decisions, we also sought to identify regions of high suitability for denning across Croatia. Methods. Using the locations of 91 dens inhabited by bears between 1982 and 2011, we opted for the presence-only modelling option in software Maxent to determine the most important predictors of den presence, and thus predict the distribution of high-value denning habitat across Croatia. Key results. We found that structural elements were the most important predictors, with ruggedness and elevation both relating positively to den presence. However, distance to nearest settlement was also positively associated with den presence. Conclusion. We determine that there is considerable denning habitat value in areas with high and rugged terrain as well as areas with limited human activity. We suspect that high and rugged terrain contains a greater concentration of the karstic formations used for denning than lower-lying regions.