Landscape factors related with common vole burrow systems abundance in agrosystems of NW Spain

Resumen del trabajo presentado al 15th Rodens et Spatium: International Conference on Rodent Biology, celebrada en Olomouc (Czech Republic) del 25 al 29 de julio de 2016.Common vole (Microtus arvalis) is an important rodent pest species in Europe. Landscape traits may be promote vole outbreaks, but little is known about this for the recently settled vole population in agricultural areas ofNWSpain.We aim to evaluate which are the main landscape traits related with the number and activity of common vole burrow systems (BS teherafter), a key trait of common vole biology reliably reflecting vole abundance, during a low-abundance year. All BS were counted in 8 circular 12.5 ha plots in spring, summer and autumn in 2012 in two study areas. We measured in each plot the area covered by each type of crop, riverine habitats and road ditches, total length of field margins and Shannon diversity index of type and state of crops. We applied to these landscape variables a Partial Least Square Regression (PLS) using three response variables: total number of BS/ha, total number of burrow openings/ha and total number of active BS/ha. Sampling locality had an important effect on the three response variables studied. BS abundance or activity varied at local scale, reaching the highest and more stable densities in permanent crops (old alfalfa fields). But given that age of alfalfa fields was variable among plots, and burrow abundance is usually low in young alfalfa, the main factor negatively affecting BS abundance/activity was the area occupied by traditional (tilled) cereal. Yearly leguminous crops also seemed to favour higher BS abundance. Area covered by riverine habitats (the main well developed natural herbaceous habitats) negatively correlated with the abundance of total and active BS in the plot. Overall, spatial and temporal arrangement of crops at landscape scale and soil disturbance through tillage may be critical traits affecting the persistence of BS and could be a major factor explaining spatial expansion of common voles in agricultural landscapes. Further data are needed about the role of linear herbaceous habitats.Peer Reviewe