engleski

Winter movements of brown bears in Croatia

European brown bears (Ursus arctos) are generally considered as winter hibernators. Our goal was to determine and compare the amount of bear movements in Croatia during January and February, as central winter months, vs. November, December, March and April, and other seasons. Studies have been undertaken from 1981 through 1997. We applied radio telemetry and snow tracking. Radio tracking revealed significantly smaller winter ranges compared to other seasons but also demonstrated certain levels of activity, both within and outside the dens. For none bears we could demonstrate to roam around all winter, but at least one subadult male (of 12 tracked bear - winters) settled down for less than two weeks in second half of January. Later careful inspection of the area failed to locate a den and seems that this bear used only a kind of day-bed. Tracking in the snow revealed the fewest tracks in January and February but proved that in each month of year at least some bears could be found moving outside the den sites. Most of tracks have been found at bear feeding sites and around some garbage dumps. At such places bears occasionally dug in the snow for consumable items demonstrating the feeding behavior. Several scats have also been found in January and February, as well. No trend of change in frequency of signs of winter bear activity has been noticed over the 16 years of this study. Our data on the influence of beech nuts crop and the severity of winter failed to show relation to the amount of bear winter movements. Most of mid-winter tracks belonged to medium sized single bears, but in January 1997 even a sign of a female with a yearling cub was found. The presence of human sources of food may be considered as the probable single most important reason why some bears remained active most of the winter. This could be compared to the situation with captive bears where the daily servings of meals keep most bears out of hibernation, while the seizure of feeding triggers hibernating behavior. Full reasons and long-term effects of increased winter activity of free-living bears could not be evaluated at this point of knowledge.

brown bear; Croatia; winter; movements

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