Seasonal variability in the diet of the forest dormouse,Dryomys nitedula, on the north-western edge of its distributional range

Abstract

The diet of the forest dormouse, Dryomys nitedula, was studied in Lithuania, which is situated on the north-western edge of its range. The diet composition of D. nitedula changes constantly over the activity period. From late April until mid-July, food of animal origin dominates the diet, while vegetable food prevails from mid-July until early September. Over the entire activity season, food of animal origin comprises on average 63 % of dormouse diet by volume estimates. Four main food groups — birds, adult insects, insect larvae and millipedes — dominate, but their proportions vary over the course of the season, as does the composition of vegetable food used by D. nitedula. Among vegetable food, dormice feed on blossoms of Norway spruce, oak and aspen in May, cones of Norway spruce during June-August, raspberries, birch seeds and fruits of glossy buckthorn in July and August and oak acorns in late August and early September. The composition of vegetable food used by D. nitedula in Lithuania is rather specific in comparison to other parts of the range and shows high dormouse adaptability to local conditions. In different years, the proportions of vegetable and animal food, as well as their compositions, vary in the dormouse diet. Dormice can accumulate sufficient fat reserves for hibernation feeding on both vegetable and animal food.