Foraging ecology of Alpine mountain hares and European hares in the Alps: is competition about food a driving force in overlapping elevations?

The Alpine mountain hare (Lepus timidus varronis) and the European hare (Lepus europaeus) live parapatrically along the elevation gradient in the Alps with areas of overlap. Indications suggest competition between the two lagomorph species in overlapping areas. Resource partitioning in form of feeding niche differentiation may reduce competition and enable coexistence. The two hare species hybridise and produce fertile hybrids. To examine foraging behaviour of Alpine mountain hares, European hares and their hybrids in the Alps with particular interest in indications of competition between the two lagomorph species, we performed genetic analysis of hare faecal samples collected on five transects along the altitudinal gradient in the Alps in Grisons (Switzerland) at the middle and the end of the vegetation growth period in the year 2021. We then investigated visually foraging ecology using Fourier-Transform Infrared Spectroscopy (FTIRS). We recorded 32 European hares, 50 Alpine mountain hares, and 18 hybrids. Foraging behaviour of the Alpine mountain hares was different from foraging behaviour of European hares and hybrids. Alpine mountain hares displayed a specialist’s foraging behaviour, whereas European hares and hybrids a generalist’s foraging behaviour. Some Alpine mountain hares inhabiting overlapping elevations with European hares showed feeding niche differentiation, whereas others showed similar feeding behaviour as European hares suggesting competition between the two species about food. Our study underlines that European hares living in the Alps might be a competitor to the Alpine mountain hare. As a specialist, the Alpine mountain hare will be susceptible to future environmental change due to climate change.