Environmental conditions in mountainous regions have influenced the nature of some adaptations among small mammals and this may apply to strategies of habitat use in alpine biotopes. In the present paper, microhabitat use in relation to microhabitat availability of a population of snow voles Chionomys nivalis Martins, 1842, a nonhibernating microtine rodent that inhabits high-mountain environments exclusively, was studied. The results show that C. nivalis did not use microhabitats in proportion to availability, suggesting a preference for certain habitat characteristics. Chionomys nivalis strongly used scree areas at all times, whereas the use of available areas of mixed shrubs (Juniperus communis and Cytisus oromediterraneus) and Scots pine (Pinus sylvestris) was lower than expected. Factors other than food, such as favourable microclimate or refuge from predators, might determine regular use of rocky microhabitats. The results also revealed differences in the use of rocky structures related to sex and reproductive condition, suggesting different strategies of spatial use related to reproductive tasks. Juveniles and reproductive females used central zones of the scree and areas with scree junipers (J. communis) significantly more than expected, whereas reproductive males and nonreproductive adults used scree areas in proportion to availability. Based on its unique morphological, physiological, and ecological characteristics, C. nivalis can be considered a rock-dwelling specialist of alpine environments.
The tropical frontier in avian climate impact research
