Evidence for improved connectivity between Cantabrian brown bear subpopulations

The brown bear (Ursus arctos) population in the Cantabrian Mountains of northwest Spain is among the most endangered bear populations worldwide. It is divided into 2 isolated and genetically differentiated subpopulations. We present evidence of recent male migration between the subpopulations based on genetic identification of hair and scats samples gathered between 2004 and 2007. Of 76 identified individuals, our analysis assigned 3 males sampled in the eastern subpopuladon to the western subpopulation. As well, I male genetically belonging to the eastern subpopulation was repeatedly sampled along his way to the western subpopulation during April to November 2006 (a linear distance of 144 km). This bear's path may help identify natural corridors, which could be improved through restoration management. In addition, we identified 2 genetically admixed individuals during 2008 in the Western limit of the eastern subpopulation range. Connectivity between subpopulations and gene flow appears to be improving after a long isolation.