Competition between sympatric hare species in the Alps is boostered by climate change and hybridisation

Climatic variation along the elevation gradient promotes the natural parapatric occurrence of the European hare (Lepus europaeus) and Alpine mountain hare (Lepus timidus varronis) in the Alps. Recent data indicate a displacement of mountain hares caused by competition with the European hare. Competitive exclusion might take place at a fine spatial scale and hybrids may sharpen competition. Genetic non-invasive sampling (gNIS) demonstrates to be effective to retrieve information from wild animals. However, based on the accuracy of the differing genetic analysis methods, the selection of the method might decisively influence results. To examine habitat preferences of Alpine mountain hares, European hares and their hybrids with particular interest in the influence of the accuracy of the genetic analysis method on the results, we performed gNIS in Grisons (Switzerland) for four years and compared habitat associations of the genotyped samples. We recorded 137 individuals (i.e., 35 hybrids, 49 European hares, 53 Alpine mountain hares). Combined nuclear and mitochondrial DNA analysis including individual identification revealed to be the most accurate indirect method for the study of habitat preferences of hares. Alpine mountain hares had a narrow habitat breadth and used little habitat diversity. Hybrids showed great similarities in their habitat preferences to European hares. Hybrids might increase the competition in favour of European hares and the displacement of Alpine mountain hares, since they show similar patterns of habitat use to European hares. Ongoing climate change potentiate the niche overlap between species, increasing the risk of Alpine hare decline due to hybridisation and displacement.