Microhabitat characteristics of brown bear den areas

Abstract

The aim of this study was to determine the microhabitat, relief and forest structure characteristics of brown bear (Ursus arctos L.) cave dens and other types of dens in the North Dinarides (Velebit Nature Park) in Croatia. In total, 63 dens were identified, consisting of 89% cave dens and 11% other den types (nest dens 6%, stump dens 3%, trunk dens 2%). In the 20-meter radius around each den, the microhabitat, relief and structural characteristics were recorded, including altitude, slope, exposition, rockiness, forest developmental stage, canopy density, tree height, forest site index, tree basal area, and tree species composition. Based on altitude, the climatic category was determined according to the Köppen climate classification. Most cave dens (62%) were in the temperate climate, at altitudes between 900 and 1,100 m, with a southern exposition and slope class between 30 to 60%. The dens situate in partial canopy density of the third forest site index with tree heights between 16 and 20 m and without forest degradation. Slopes and tree heights were lower (p < 0.019) in cave den areas in comparison to other den types. Keywords: cave dens, microhabitat, forest structure, North Dinarides, Velebit Nature Park