Miguel de gabriel Hernando, Alexander Kopatz, Lambros Krambokoukis, Tomaž Skrbinšek

At the southernmost edge of the brown bear’s (Ursus arctos) European distribution, Greece hosts a population once considered fragmented and vulnerable. The “Hellenic Bear Register” (2000–2025) is one of the longest-running genetic monitoring initiatives for bears in southeastern Europe, established to inform conservation and adaptive management amid rapid demographic change.
Using primarily non-invasive samples (hair and scat), complemented by blood and tissue, we analysed 1,300 samples across 18 microsatellite loci to assess genetic diversity, population structure, gene flow, effective population size, kinship, and dispersal. We identified 500 unique genotypes, including 450 from Greece and 50 from neighbouring countries, for transboundary comparison.
Our results indicate a dynamic, recovering system. The western Greek subpopulation exhibits the lowest genetic diversity recorded in southeastern Europe, yet remains more robust than other genetically depauperate bear populations. Historically distinct eastern and western populations show pronounced substructuring, particularly in the west. However, this structure is now dissolving. As numbers increase, we document a “recovery cascade” driven by asymmetric south-to-north gene flow among neighbouring subpopulations, mediated primarily by males.
Effective population size exceeds previous assumptions, corroborating field evidence of rapid recovery. We document strong male-biased dispersal, movements exceeding 75 km, and individual monitoring histories spanning more than 15 years—demonstrating how small, persisting nuclei can function as stepping stones for large-scale expansion.
The “Hellenic Bear Register” provides a rare long-term genetic lens on recovery at a range periphery. By revealing an active recovery cascade rather than persistent fragmentation, our findings demonstrate how sustained genetic monitoring can detect resilience in real time and support science-based management in landscapes where coexistence an