Genetic monitoring 2023
Between 2023 and 2025, a national brown bear monitoring project entitled “Assessment of the brown bear population in Slovenia in 2023 and certain other demographic parameters” was carried out in Slovenia. The project was funded by the Ministry of Natural Resources and Spatial Planning and implemented by the Slovenian Forest Service. Six other organizations were involved in the individual phases of implementation: the DivjaLabs genetic laboratory, the Slovenian Hunting Association, the Faculty of Biotechnology at the University of Ljubljana, Klemen Jerina Research, the Dinaricum Society, and Matson’s Laboratory.
The main goal of the project was to determine the brown bear population in Slovenia using the non-invasive genetic-molecular methods. To obtain a reliable estimate, it was necessary to collect a large number of genetic samples, mainly from feces. Field collection took place in the fall of 2023, with active participation of hunters, foresters, and other visitors to the natural environment. The laboratory analysis procedures were followed by complex statistical processing and population modeling, and the final results of the genetic count were obtained in early 2025.
The action to collect and send in feces samples was an enormous success, with almost a thousand people, mostly hunters and foresters, sending in samples. A total of 2,863 non-invasive genetic samples were collected, based on which 656 different brown bears were identified, that is, 261 males and 395 females. Using the capture-mark-recapture method, we also estimated the number of undetected individuals and thus determined the total population size at the end of 2023 to be 737 individuals (695–797; 95% confidence interval).
This is the lowest annual, i.e., autumn estimate of abundance, which already includes all recorded mortality and applies to the period just before the birth of young. A comparison with genetic estimates from 2007 and 2015 shows that the population has grown approximately linearly over the last 16 years. In addition to the increase in numbers, there has also been a spatial expansion of the population, most pronounced in the Zasavje region, while females are gradually spreading towards the western part of the country. Whereas in the Alpine region, it is still only males who are present.
At the same time, analysis of the genetic data collected shows that the growth of the brown bear population in western Slovenia has stalled over the last decade. During the entire sampling period, we detected only 45 different individuals on the northwestern side of the Primorska motorway, of which 21 were females, and 24 were males. Of these, only nine individuals were recorded on both sides of the motorway, indicating that the Primorska motorway represents a significant spatial barrier to the movement of bears between the Dinarides and the Alps.
Based on the results of the genetic census, a prediction of future population dynamics was also made. Prof. Dr. Klemen Jerina from the Faculty of Biotechnology at the University of Ljubljana combined genetic estimates with data on bear removals and prepared a projection of population development after 2023. The calculations show that in the spring of 2025, there were approximately 954 bears in Slovenia (880–1050; 95% confidence interval), which represents the highest annual abundance after the birth of cubs and before annual mortality.
Based on the results obtained, we can conclude that the brown bear population in Slovenia is in very good condition. Genetic counting provides a reliable insight into the structure and dynamics of the population and represents a solid scientific basis for its long-term and sustainable management.
Poročilo monitoringa o oceni številčnosti rjavega medveda v Sloveniji v letu 2023 (https://www.gov.si/novice/2026-03-12-porocilo-monitoringa-o-oceni-stevilcnosti-rjavega-medveda-v-sloveniji-v-letu-2023/ )