The winter diet of the great tit (Parus major) was examined in mixed and deciduous forest in central Slovakia during three winters. Using a faecal samples analysis, in 105 sampled roosting individuals (in nestboxes) at least 37 taxa of invertebrates were found. Apart from the invertebrates, plant material was identified in dissected birds’ droppings as well. There were no significant differences in the winter food composition between sexes. Generally, plant material was the most frequent and the most dominant winter food. This component was followed by moths, beetles and dipterans. While comparing the relative volume between two distinct habitats, the most significant difference was found in Lepidoptera adults and plant material. Birds from mixed forest foraged less on Lepidoptera adults in contrast to individuals from deciduous forest. This could be compensated by bigger consumption of seeds and buds there. Regarding seasonal changes, within five winter months (from November to March), the relative volume and frequency of some invertebrate groups (Heteroptera, Homoptera and Lepidoptera) significantly increased with the temperature but no correlations were found with other weather characteristics. Invertebrates exhibited the opposite seasonal pattern compared to the plant material.
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.