Winter activity rhythms of a rodent pest species in agricultural habitats

Predation risk is the main factor affecting movements of mammal prey species. Here we assessed the activity patterns of a nearly endemic fossorial rodent, the Savi's pine vole Microtus savii, in two agroecosystems in central Italy. Direct captures were carried out in cold months (December-March) with live-traps; sex and age were recorded for each captured individual following standard methods. Savi's pine voles were mostly active during daytime in both study sites, with no differences between sexes or age classes. Night-time movements were mainly registered during waning moon nights and were severely restricted in bright moonlight. The activity pattern of Savi's pine voles seems to support the hypothesis of predation avoidance. The most common predators of these small rodents are mainly active during bright nights, when visibility is highest, forcing voles to be more active aboveground during daylight hours as well as in the darkest nights. Efficient monitoring and trapping programmes should therefore take place in daylight hours to increase capture success and to reduce stress levels of the captured animals.