Nest site selection by the hazel dormouse Muscardinus avellanarius: is safety more important than food?

Abstract

Vegetation parameters determining nest site selection by the hazel dormouse Muscardinus avellanarius were studied in a typical habitat where dormice are relatively common in Lithuania, the northern periphery of its distributional range. Dormice preferred nest sites with a better-developed understory, particularly with a good cover of hazel shrubs taller than 4 m and plentiful bird cherry trees, a high diversity of woody plant species in the understory and overstory, and better connectivity of the nest tree with its surroundings. They avoided sites with a high number of mature Norway spruce trees in the canopy and a high density of young trees. In a stepwise multiple regression analysis, three vegetation parameters of the number of shrub species, the cover of hazel shrubs, and the number of Norway spruce trees in the canopy determined over 85% of the index of nestbox use by M. avellanarius. The number of shrub species in the surroundings of the nest site had the highest impact of all. Nest sites used by dormice for breeding were distinguished by a better-developed understory, particularly by a significantly higher number of bird cherry trees and a lower number of Norway spruce trees in the canopy, as well as a higher diversity of plants in the understory and overstory. Selection of nest sites by M. avellanarius is a combination of safety from predators and the presence of food. A well-developed inter-connected understory ensures the safety of nest sites from predators, and the diversity of understory and overstory species guarantees continuity of the food supply in the vicinity of nest sites.