The influence of high nestbox density on the common dormouse Muscardinus avellanarius population

The response of common dormouse Muscardinus avellanarius Linna us, 1758 population to availability of nest sites was studied by manipulating the nestbox grid and ring-marking dormice. Abundance of adult dormice more than doubled in the 25 x 25 m nestbox grid in comparison to the 50 x 50 m grid, as a result of increased nestbox density from four to 16 boxes/ha. This effect already became apparent in the first year after additional nestboxes were made available and resulted from dormouse immigration, mostly from adjacent areas without nestboxes. In the second and third years, the number of two-year-old and older resident dormice, which had their home ranges in this plot, increased considerably. The average size of dormouse home range decreased by approximately half both in males and females in the 25 x 25 m grid compared to the 50 x 50 m grid. The proportion of breeding adult females did not differ between the two grids in spite of different adult dormouse density. Shortage of secure nest sites was a limiting factor for the common dormouse population abundance in the forest where natural tree hollows were absent, and high nestbox density increased environmental carrying capacity.