Temperature increase and frost decrease driving upslope elevational range shifts in Alpine grouse and hares.

ABSTRACT

Global climate change has led to range shifts in plants and animals, thus threatening biodiversity. Latitudinal shifts have been shown to be more pronounced than elevational shifts, implying that northern range edge margins may be more capable to keeping pace with warming than upper elevational limits. Additionally, global climate change is expected to disadvantage habitat specialists. In the Alps, climatic variation along the elevation gradient allows the coexistence of habitat specialists and generalists. Alpine species are anticipated to adapt their elevational ranges to the change of various climate variables caused by global climate change. Regional differences might buffer elevational shifts. Furthermore, distinct climate variables might differently affect the shifts of habitat specialists and generalists. To study the effect of climate change on Alpine species, we analysed hunting bag, climate and biogeographical data of two grouse species (Tetrao tetrix and Lagopus muta) and two hare species (Lepus timidus varronis and L. europaeus) in Grisons, Switzerland, over a period of 30 years. Our results based on 84,630 harvested specimens were as follows (1) only three out of seven climate variables changed significantly within the study period. (2) The grouse species significantly shifted towards higher elevations, whereas the hare species only shifted in their minimum/maximum elevations. (3) Hunting elevation of habitat generalists increased more than in habitat specialists. (4) The elevational shifts were mostly related to the number of frost days. (5) Hunting elevation increased especially in the southern biogeographical region. To conclude, all four taxa respond to climate change but habitat generalists more rapidly than habitat specialists. The range shift to higher elevations due to global climate change will lead to a reduction in habitat availability for snow-adapted species. Climate change is thus a serious threat to alpine biodiversity. Regions rich in alpine habitats will have an increased responsibility to conserve these species.