Factors affecting occupancy by the European mink in south-western Europe

The European mink is an endangered species in need of urgent conservation efforts, but whose decline and habitat requirements are only poorly known. In this study we developed a model for mink distribution in Biscay to catalogue variables influencing its presence/absence. Sites were described in terms of vegetation parameters, water quality, riverbank alteration, anthropogenic structures and American mink presence. Logistic regression analysis was used to identify ruling variables and synergies. The model extracted two variables of high significance: water quality and riverbank alteration. European mink was absent from polluted waters and canalised streams. The absence is explained by a decrease in prey availability. In the case of water pollution, bioaccumulation is considered to have a deleterious effect on the presence of the species. In the case of canalisation, the lack of adequate shelter areas and especially the depletion of food resources are also likely to play an important role explaining the absence of the species. Finally, the possible barrier effect of canalisation for European mink and its consequences are also discussed. For the remaining variables, only those describing habitat use by European mink within its home range seemed to have a little influence on the presence of the species. The presence of American mink was a poor predictor of the absence of its European counterpart. Based on the results, we suggest that improved riverbank management policies are needed to ensure the future of European mink in the area. Species introduction and reintroduction programs should consider our habitat model when searching for suitable areas for the species. Further research is also needed on the effect of diverse types of water pollution on European mink.