Ecological drivers of garden dormouse (<i>Eliomys quercinus</i>) occupancy in a human modified landscape in Germany

Abstract The garden dormouse ( Eliomys quercinus ) is an understudied mammal species endemic to Europe. Once distributed widely across the continent, its eastern populations have significantly declined, with the species now found in only 50% of its former range. In Germany, it also occurs in spruce forests in low mountain ranges. However, this habitat has recently been lost due to bark beetle infestation following a prolonged period of drought. In some places, not only the dead trees are removed, but also all the branches and topsoil. We assessed habitat requirements of a garden dormouse population in such a changing habitat in the Harz Mountains, Germany. To assess garden dormouse occupancy, we conducted transect surveys using footprint tunnels during July and October 2022 for the presence of garden dormice. Additionally, we measured covariates such as coverage of tree, shrub and herb layers, as well as deadwood, soil characteristics and reforestation. Using single‐season occupancy modelling, we evaluated the effects of these habitat covariates on the occupancy of the garden dormouse. Our results indicated that garden dormouse occupancy was negatively affected by herb cover but positively associated with plant successional stages. Furthermore, occupancy of the garden dormouse was positively coupled with the occurrence of the hazel dormouse ( Muscardinus avellanarius ). Detection probability increased with higher weekly minimum temperatures. Practical implications: For the conservation of garden dormice in low mountain ranges like the Harz, practical measures should include establishing interconnected forest edges and strips. Moreover, we suggest adopting a dynamic, mosaic approach to felling, avoiding topsoil removal and promoting regeneration that fosters semi‐open successional habitats as essential strategies.