Spill over of the common voles from rape fields to adjacent crops

This study investigates the impact of the common vole on cereal crops adjacent to winter rape in a rodent outbreak year. Significant damage was found at the margins of adjacent cereal fields, indicating direct colonisation by voles from the winter rape fields. The damage gradually decreased towards the centre of the fields. We suppose that the reduction of winter rape quality as food connected with plant phenophase (ripening phase) resulted in spill-over of the voles to an adjacent crops. We also observed that spring barley crops were damaged more than winter wheat. We assume that this happened due to the fact that there was no barrier between fields of spring barley and winter rape, while wheat and rape fields were separated by a road. The number of voles at the barley field margin was significantly lower than in the middle (significantly in barley, non-significantly in wheat), which may be related to the depletion of resources at the margins. The abundance of voles appearing in rape was significantly lower than in cereals; in its ripening phase winter rape has low habitat value for voles. This study indicates that voles can cause the same amount of damage to cereals adjacent to winter rape as to cereals adjacent to their primary habitats (e.g. grassland). This is especially evident in years of vole outbreak.