Recurring outbreaks of common vole (Microtus arvalis) in grasslands in the low-lying parts of the Netherlands

Abstract: In the past, outbreaks of common voles (Microtus arvalis) were a regular occurrence in agricultural grassland areas in the Netherlands, but they have been virtually absent in recent decades. However, after 2000 there have been three major outbreaks, in 2004-2005, 2014-2015 and in 2019-2020. To gain more insight into the distribution and underlying causes, this paper documents the occurrence of outbreaks in the Netherlands and maps the distribution during the recent outbreaks in the province of Friesland. In addition, a spatial analysis of damage reports of farmers during the outbreak in 2014-2015 has been carried out. The analysis shows that large outbreaks mainly occur in open landscapes on clay and peat soils that are drained intensively. The number of damage records is lower in case of pasture grazing. We conclude, that the intensive agricultural management of grasslands may not be the cause of outbreaks, but today’s dairy farming practices with low water tables and less grazing of pasture, support outbreaks rather than dampening them.