How do large herbivores cope with decreasing precipitation in temperate forest ecosystems?

Environmental conditions are a key aspect in shaping space-use and habitat selection of large herbivores. However, how weather extremes, such as prolonged periods of low precipitation, impact habitat selection processes in temperate ecosystems remains understudied. Understanding these dynamics is increasingly urgent, as climate change is expected to intensify the frequency and duration of low-precipitation periods. This study aimed to assess how selection of wet habitats by the European bison ( Bison bonasus ), the largest European herbivore with high water requirements, changed under varying precipitation levels in summer. Using GPS data of 22 European bison in the Polish part of the Białowieża Primaeval Forest, we tested the effect of sex and precipitation on the selection of the wettest habitats within individual bison summer ranges by means of a step-selection analysis, and predicted selection under different precipitation levels. Our results showed that female bison showed a stronger selection for wet habitats than males, but we found no difference between the sexes for precipitation-dependent selection. Precipitation influenced habitat selection, but primarily among individuals whose summer ranges included a greater availability of wet habitats. Bison occurring in the wettest part of the forest increased their selection of wet habitats under low precipitation levels, whereas no such selection was observed for periods of high precipitation. In contrast, bison occupying drier habitat ranges showed no selection for wet habitats, regardless of precipitation. Overall, these findings suggest that the relationship between habitat selection and precipitation depends on the wetness of the summer ranges occupied by bison. Our findings expand our understanding of how large herbivores respond to environmental variability in temperate forests, suggesting the importance of wet habitats for these animals in the context of climate change.