From science to practice: genetic estimate of brown bear population size in Slovenia and how it influenced bear management

Abstract

Rapid development of molecular genetics has provided ecologists and wildlife managers with a powerful set of tools for studying and monitoring wildlife. We applied these tools to estimate the size of the brown bear population in Slovenia in 2007. In the years after the estimate was made public, we followed how this estimate affected policy and management actions in Slovenian bear management. We designed and executed a large-scale noninvasive genetic sampling across the range of this species in the country with a network of volunteers and estimated the size of the brown bear population in Slovenia using mark-recapture modeling. In a highly intensive 3-month sampling in autumn 2007, we collected 1057 samples. A total of 931 samples were successfully genotyped, yielding 354 different genotypes. Using mark-recapture and correcting for the edge effect caused by bears moving in and out of the sampling area across the Slovenian-Croatian border, and accounting for detected mortality, we estimated “winter” population size (after annual mortality, before reproduction) at 424 (95% confidence interval 383–458). We also observed an uneven male and female ratio of 0.405 and 0.595, respectively. Using “citizen science,” we managed to conduct a highly intensive large-scale sampling with modest financial resources, something that would be impossible to do otherwise. We produced the first robust, scientifically defensible estimate of the brown bear population size in Slovenia. Although at first reluctantly considered by managers as equivalent to other “traditional” population monitoring data, awareness of the importance of the estimate grew with time. It became the first reference point for understanding population dynamics, a basis to which current and future development of the population is being compared to. As such, we can expect it will profoundly affect Slovenian bear management in the years to come.