The habitat preference of root voles in Nieuwkoopse Plassen, the Netherlands

Abstract: The root vole (Alexandromys oeconomus arenicola) is one of the species for which Nieuwkoopse Plassen & De Haeck (Provinces of Zuid-Holland and Utrecht, the Netherlands) has been designated as a Natura 2000 site. This subspecies is endemic to the Netherlands and can only be found in five regions in the country. The decline of root vole populations is mainly due to the loss of suitable habitat and to competition with other vole species, especially the field vole (Microtus agrestis), the common vole (Microtus arvalis) and bank vole (Myodes glareolus). The main research questions were: what is the relation between vegetation type, type of land management and location within the field on the abundance of root voles in Nieuwkoopse Plassen & De Haeck? It was expected that root voles would prefer extensively managed reed vegetations and rough wet grasslands and that root voles prefer sites close to the edge, as opposed to the centre of fields. It was found that lowland hay meadows, a habitat type that has almost completely disappeared in recent years, and helophytes vegetation are important vegetation types for root voles. Fen woodlots and grasslands dominated by velvet grass (Holcus lanatus) or ryegrass (Lolium perenne) were found to have the lowest abundance of root voles. Winter mown vegetation where clippings were burnt held higher numbers of root voles, whereas hayfields that were mowed in mid June and grazed for some time before and after mowing were not good for root voles. Within the fields root voles preferred locations close to the edge over central locations.