Emiliano Manzo

Field identification of Apodemus flavicollis and Apodemus sylvaticus: a quantitative comparison of different biometric measurements

Abstract The identification of the wood mouse Apodemus sylvaticus and the yellow-necked mouse Apodemus flavicollis in the field has challenged many generations of field mammalogists, particularly in northern Spain and continental Italy. These two species present highly similar morphologic and morphometric characteristics especially when they are sympatric. Existing identification methods rely on morphometric and biometric measurements collected on killed or etherized animals, whereas in many field studies measurement may be taken only on live and awake animals. Genetic methods, instead, are time consuming, expensive and do not allow immediate identification in the field, which is a requirement in many types of ecological works. To contribute in filling this knowledge gap, the aims of this research were: 1) to assess biometric measurements (weight and length of hind foot) that allow species identification on live and awake animals and 2) to develop a predictive model and related software that, subject to refinement based on study area, will allow researchers to prioritise the selection of individuals to be identified by molecular approach. This model, based on a large (>1500) sample of individuals captured in two different sites in central Italy, should help to classify live and awake individuals of Apodemus species. Attached to this paper is a Microsoft Excel spreadsheet that may be used to apply the model to new data.

Weasel Mustela nivalis spatial ranging behaviour and habitat selection in agricultural landscape

This paper reports the findings of a study on the spacing pattern of a population of weaselsMustela nivalis Linnaeus, 1758 in central Italy. We describe this pattern at spatial and habitat level, meant as a set of vegetational and environmental features. The study area is a typical agricultural landscape, consisting of highly fragmented natural habitat modified by thousands of years of human presence and work. The results indicate that individual home ranges vary greatly from non breeding to breeding season: during spring and summer, weasels increase their movements and the number of tracts they cross, which results in home range areas up to 10 times larger. Moreover this study demonstrates a strong preference of weasels for habitats formed by natural residual edges between fields and meadows. The shapes of the individual home ranges follow these edges, producing a typical linear spatial home range pattern.

Acorn choice by small mammals in a Mediterranean deciduous oak forest

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.

Seasonal cravings: plant food preferences of syntopic small mammals

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.

Difficulty in visual sex identification: a case study on bank voles

Abstract The present study aims at quantifying the error in visual sexing of live-trapped bank voles and evaluating if animal body weight and experience of field workers affected the ability to determine the sex of voles. The error in sex attribution involved 25.6% of non-reproductive individuals, pointing out the need to validate the field sex identification. Body weight of voles did not affect the ability of trappers to visually discriminate the sex of animals. Field workers had similar percentages of error independently of their expertise in vole sexing but they also showed a sex-bias in wrongly sexed individuals.

Habitat selection of European pine marten in Central Italy: from a tree dependent to a generalist species

Studies at small spatial scale are often fundamental to highlight the behavioural plasticity of a species and thus have important implications for conservation planning, in particular for species usually considered as habitat specialists. We investigated second-order habitat selection of the European pine marten in an area dominated by deciduous oak forest and open fields in central Italy, by radio-tracking 16 pine martens (eight males, eight females). Pine martens placed home ranges in areas with more open field than in the study area, whereas woodland (oak and conifer forests) comprised a smaller portion of the home range than predominant forest character of the studied area. Although the presence of the species in the open habitats has been documented, to our knowledge, our results provide the first evidence of home range establishment in this cover type by pine marten at population level. The combination of low predation risk and high availability of resources could allow pine martens to occupy open fields in our study area. We highlighted different individual strategies of habitat selection, with some individuals placing home ranges in areas with high forest coverage while others occupying open areas. We found no effects of sex and body condition on habitat selection, and this could indicate that in the study area, both forested and non-forested cover types, such as open fields, shrub and anthropic areas, can provide adequate food, overhead cover and resting sites for all individuals. Pine marten ability to occupy open fields seems thus more related to the behavioural flexibility of the species, rather than to the need to supplement dens and forage from complementary lower quality habitat. The high quality of the Mediterranean continental area studied could also explain the selection of open areas by the pine marten. Our results offer useful information on pine marten ecology and may be helpful for conservation management of this species in southern Europe.