Having a thorough understanding of animal feeding behaviour is a basic aim in ecology. Food represents a crucial resource that can strongly rule animal populations, especially where food supplies are seasonal, such as in temperate areas. In Italy, sub-Mediterranean forests dominated by deciduous oaks are commonly inhabited by the yellow-necked mouse Apodemus flavicollis, the wood mouse A. sylvaticus and the bank vole Myodes glareolus. Despite the rich literature regarding their diet composition in northern Europe, to our knowledge no studies have been published on food preferences of these rodents in syntopy in sub-Mediterranean deciduous forests. Feeding preferences of 33 A. flavicollis, 10 A. sylvaticus and 18 M. glareolus on reproductive parts (flowers, unripe and ripe fruits) of 26 representative plant species in a deciduous oak forest of central Italy were investigated through seasonal cafeteria-style experiments. Our findings evidence that A. flavicollis exhibited distinct preferences in all seasons, highlighting a relevant affinity only for a strict array of plant species, and acting as seed specialist. Apodemus sylvaticus showed generalist food habits, eating all foods with similar consumption patterns, whereas M. glareolus occupied an intermediate position between the Apodemus spp. Indeed the bank vole did not show a clear preference for some foods over others in spring and summer, while in autumn the consumption significantly differed resulting in a strong preferences overlap with A. flavicollis. This result suggests potential competitive interactions between these rodents in our study area, especially regarding a crucial resource such as acorns. By using seasonal cafeteria-style experiments we were able to delineate the feeding behaviour and preferences of A. flavicollis, A. sylvaticus and M. glareolus towards several plant parts pertaining to a wide array of species. Our findings can help future studies regarding these rodents focusing on factors influencing their population dynamics, such as trophic resources and competition.

Several studies regarding acorn choice by granivorous rodents have been conducted in dry Mediterranean oak forests, mainly composed by evergreen oaks. However, a lack of knowledge still persists about this subject in sub-Mediterranean forests dominated by deciduous oaks. We investigated the choice between Quercus cerris and Q. pubescens acorns by terrestrial small mammals in a deciduous oak forest of Central Italy, dominated by Q. cerris. Using a cafeteria-style feeding experiment, we tested 14 Apodemus flavicollis, and 10 Myodes glareolus. Animals were kept in outdoor experimental enclosures and given simultaneously a sample of acorns of the two oak species collected in situ. All seeds were sound and of the same size, shape and weight. Seed consumption was checked regularly, to record the percentage of consumed acorn sample. To evaluate a possible influence of pericarp on choice, acorns were presented both whole and shelled. Biochemical composition of seeds was analysed. Acorns of both oaks were similar in protein, lipid, carbohydrate and ash contents and energetic value, differing only in tannins and fibre content, with Q. pubescens having 51% less tannins and 35% less fibres than Q. cerris. The cafeteria experiments revealed a significant feeding preference by rodents for the less common Q. pubescens acorns, except for M. glareolus when presented with whole acorns. This overall preference, observed also at the individual level, could reflect a general foraging strategy aimed at maximising metabolisable energy and nutrients intake, avoiding anti-nutrients (i.e. tannins). To our knowledge, this is the first study on acorn choice by terrestrial rodents in sub-Mediterranean deciduous oak forests. Our findings not only provide information about the feeding behaviour of these species, but also may help future researchers to evaluate the role of these food resources in small mammal abundance, spatial distribution and population dynamics.

The wood mouse Apodemus sylvaticus is common in woodlands and open areas of the Western Palearctic. Despite extensive research, little is known about its population ecology in fields in the Mediterranean area, where the climate involves great seasonal changes in environmental features. Here, we investigated wood mice seasonal fluctuations in the number of captures and population structure by sampling long-fallow fields and woodlands, i.e., oak forest and conifer plantation, in a heterogeneous landscape of central Italy. Mice were live-trapped every two months for three years (23.814 trap-days). The number of captures, mice body weight, and proportion of adult, residents and breeding individuals were analyzed. Mice dynamics changed across seasons and habitats. In fields, we recorded more captures, more reproductive individuals, and fewer non-adults and resident individuals in the warmer months compared to the colder months; mice were heavier in warmer months. During the cold season, the captures and adult proportion in fields were lower than in resource-rich woodlands. Breeding and non-resident mice were more abundant in fields than in woodlands in warmer months. Overall, the seasonal demographic variations we recorded provide evidence that fields can represent a suboptimal habitat in Mediterranean heterogeneous landscapes, acting nonetheless as a source of food resources, cover, and mates for mice in spring–summer.