Insights into the fine-scale habitat use of Eurasian Water Shrew (Neomys fodiens) using radio tracking and LiDAR

Abstract The Eurasian Water Shrew (Neomys fodiens) is one of the largest shrew (Soricidae) species in Eurasia. In Western Europe, this semiaquatic species often occurs in riparian and marshland habitats that have a high degree of naturalness, but is being threatened by habitat degradation and other anthropogenic factors. The species mostly occurs in low abundance and is elusive. Therefore, understanding its habitat use is challenging, yet imperative for establishing species-specific conservation measures. Technological developments in radio tracking and high-resolution remote sensing such as Light Detection And Ranging (LiDAR) now enable the quantification of ecological niches and provide insight into habitat requirements for a species. Here, we combined radio tracking and LiDAR to quantify habitat use by Eurasian water shrews. Alongside a lowland brook in the Netherlands, 20 individuals were tracked between September and October 2022, resulting in 332 unique locations of Eurasian water shrews. For each of these locations, 11 LiDAR-derived variables were calculated and subsequently analyzed in a species distribution model (SDM). The SDM yielded a model with a high accuracy (predictive performance AUC = 0.93). The variable of highest importance was dense and relatively short vegetation <1 m, which had a positive effect on Eurasian Water Shrew occurrence. Open areas seem to be avoided. Vegetation of heights between 1 and 15 m were found to be less important for the occurrence. The probability of occurrence decreased with increasing distance to water, indicating that the species occurs in the proximity of water, although vegetation-related variables were more important. The obtained detailed knowledge of fine-scale habitat use can be used to improve habitat conservation, restoration, and management for the species. Combining radiotelemetry data with LiDAR data is a promising approach to identifying species–habitat relationships of elusive species such as the Eurasian Water Shrew.