The Long-Term Dynamics of Shrew Communities: Is There a Downward Trend?

Abstract

Compared to other small mammals, shrews are understudied due to their limited impact on agriculture, lower biomedical importance, and difficulty to study. Based on trapping data from 1975–2023, we investigated changes in Lithuanian shrews (Sorex araneus, Sorex minutus, Neomys fodiens, and Neomys milleri) over six decades. We analyzed the relative abundance of shrews and the proportion of their species within small mammal communities to assess temporal patterns and distribution in major habitat types. The first main finding was the confirmation of a decrease in S. araneus abundance in the 2020s compared to the 1990s and 2010s. The species proportion in 2020s was lower than in the 1970s–2000s; the decrease started in the 1980s and accelerated in the 2000s. Abundances and proportions of S. minutus and N. fodiens showed no significant trend. The abundance of N. fodiens was very low. The relative abundances and proportions of Sorex species were highest in commensal (human-related) and mixed (including forest, wetland, and meadow) habitats. Shrews were underrepresented in agricultural habitats, with the numbers of both S. araneus and S. minutus 4.1 times lower than expected. While the presence of S. minutus in commensal habitats could be explained by their diet specificity, the capture of N. fodiens and N. milleri in commensal habitats is a novel feature of their ecology.