Global warming is promoting the rapid invasion of the mountain hare range by the european hare in the Alps

In the European Alps, where the mountain hare Lepus timidus partly overlaps with the European hare (L. europaeus), climate change, hybridization and gene introgression are thought to interact, with synergic adverse effects on the mountain hare. However, to depict future scenarios for conserving the mountain hare is not feasible without knowledge of the magnitude and geographical pattern of hare distribution. As a first attempt to fill this gap and assess the impacts of climate change, we investigated the distributional pattern of hare species in a valley in the Western Italian Alps using non-invasive genetic techniques based on mtDNA, and resampling the same locations after 12 years (2009–2021). The mountain hare was more common as altitude increases, in pioneer vegetation and rocky areas. However, we also detected the European hare at high altitudes, in atypical landscapes for this lowland species, and the overlap area between hares was quite broad. The proportion of European hare samples increased in time, and the co-occurrence pattern changed, with an increase of the European hare at intermediate-high altitudes. Our data allowed us to assess directly, and for the first time, the impact of climate change on hare species in the Italian Alps. The mountain hare-only areas seem restricted to a very narrow, high-altitude strip. The considerable spatial overlap suggests that the European-mountain hare system could evolve towards a complete admixture situation. Conservation measures should aim to mitigate climate change effects and appropriately manage European hare populations.