Diet niches of the Alpine mountain hare (Lepus timidus varronis) and European hare (Lepus europaeus) living in coexistence in the Alps

Abstract

A species’ diet niche is shaped by the evolutionary processes of adaptation to the available food resources in its habitat and by competition with ecologically similar species. In the European Alps, Alpine mountain hares (Lepus timidus varronis) and European hares (Lepus europaeus) occur parapatrically along the elevation gradient and hybridise with each other in overlapping areas. Evidence that the areas of overlap are not stable suggests that interspecific competition between the two congeneric hare species is strong. Competitive exclusion might take place at a fine spatial scale and influence the feeding behaviour of the two hare species. In this study, we investigated diet ecology of Alpine mountain hares, European hares and their hybrids in the Alps in the middle and at the end of the plant vegetation growth period by collecting hare faeces along the altitudinal gradient in Grisons (Switzerland). We performed genetic analysis to identify the hare species and analysed the faeces microscopically to determine dietary composition. Plant components at the level of dicotyledons/monocotyledons, plant family and plant species in faeces of 49 European hares, 16 Alpine mountain hares and 22 hybrids (with discordant nuclear and mitochondrial genetic backgrounds) were identified. Alpine mountain hares used significantly more Ericaceae as food plants than European hares and hybrids. As mountain hares support phenolics in the nutrition better than European hares, our results suggest that the diet of the two lagomorph species are affected by phenolics content in the Alpine ecosystem. Our findings underline the Alpine mountain hare’s adaptation to the Alpine ecosystem by using characteristic Alpine vegetation as food plants. The phenolics tolerance and specialist feeding strategy might be a decisive advantage of the Alpine mountain hare in the competition between the two lagomorph species in the Alps.