TOPERAS: Molehill counts in Montaña Palentina (Spain)

[Description of methods used for collection/generation of data] The purpose of the sampling was to obtain an index of montane water vole (Arvicola amphibius cantabriae) abundance. For this purpose, 278 fixed sampling points (locationID) were chosen in the study area, resampling them every year. The points are located in Meadows and grasslands. The selection was random, using QGIS, with two constraints: they had to be more than 100 m away from each other and that they were less than 500 m from the road. From the year 2023 onwards, 25 other points within forest habitats were selected with the same characteristics. At each points, a 100 m transect was made, parallel to the riverbeds, to maintain constant soil and moisture conditions. Each transect was divided into 20 segments, 5 m long by 5 m wide (2.5 m on each side of the line of advance), and the presence/absence of signs in each segment was noted. In this way, an abundance index was obtained, ranging from 0 (no signs found) to 20 (signs present in all segments). This value correlates with the abundance of the species (Giraudoux et al. 1995). Sampling was repeated annually in late September/early October. Although the target species to be counted was the montane water vole, the presence of Lusitanian pine vole (Microtus lusitanicus), Iberian mole (Talpa occidentalis), cattle and horse was also noted. The molehills of the wild species were differentiated by their characteristics of size, shape, entrance and disposition (Miñarro et al. 2012). For domestic species, the presence/absence of dung in each section was noted.