The hazel dormouse "Muscardinus avellanarius" prefers more often forest edges before and after hibernation

Biodiversity loss is a worldwide crisis that has been worsening over the last century. To preserve species from extinction, conservation plans can be implemented. For that matter, knowledge about species is necessary. However, there are many knowledge gaps amongst many taxa. This study focuses on the hazel dormouse Muscardinus avellanarius, an endangered rodent present in Switzerland, particularly sensitive to habitat degradation and destruction. It deals with the different habitat types that the hazel dormouse can occupy throughout the year. The goal is to understand the dynamic of the species’ occupancy and to uncover where the species occurs most before and after hibernation, given that there might be a difference in the habitat preference between fall and spring. To research that, 150 footprint tunnels were used in the Val-de-Ruz (canton of Neuchâtel) and Gantrisch (canton of Bern) regions in Switzerland. They were placed in hedgerows, forest edges and structured forests. Every week, the 30 transects, composed of 25 footprint tunnels for each habitat type category in each region, were checked for two months before and after the hibernation of the hazel dormouse. Detection/non-detection data was recorded thanks to the identification of the footprints. Occupancy models were fitted to account for imperfect detection. The habitat type impacts significantly the occupancy of the hazel dormouse: the species seems to prefer forest edges to hedgerows or structured forests. The interaction between the habitat type and the season also has a significant influence on its occupancy: forest edges occupancy decreases between fall and spring. However, in hedgerows and structured forests, occupancy is indicated to be low and constant between seasons. The slope is the only topographical variable to significantly influence occupancy, with a steeper slope decreasing hazel dormouse occupancy. Thanks to the survey conducted in three different habitat types, this study could demonstrate that the hazel dormouse is not as associated with hedgerows as the literature suggests. Forest habitats are more preferred by the hazel dormouse, whether it is before or after hibernation.