Effects of roads on spatial distribution, abundance and mortality of brown hare (Lepus europaeus) in Switzerland DN:

摘要

Brown hare populations (Lepus europaeus) are in decline throughout Europe since the 1960s, and numerous impact factors have been discussed in the literature. Although landscape fragmentation by roads is assumed to be one potential factor, the effects of roads on brown hare populations are poorly understood. We studied three potential effects of roads on brown hares asking: (1) Do roads affect the spatial distribution of hares due to disturbance effects? (2) Does road network density affect hare abundance due to barrier effects? (3) Does road network density affect road mortality rates in hare populations? The study is based on harvest statistics and spotlight taxations in Canton Aargau, Switzerland and was conducted at three different spatial scales. Spatial distribution was studied in plots established in varying distances parallel to roads, effects on abundance were analysed on the basis of raster grids, and road mortality was studied on the level of hunting districts. We show that (1) hares avoid the proximity to roads and prefer large non-fragmented areas over small isolated patches. (2) The density of freeways, federal and main roads has a negative effect on hare abundance. The density of unpaved field tracks has a positive effect probably because vegetation at field tracks contributes to the diet spectrum. (3) Effects of road network density on road mortality rates could not be shown, although road mortality has increased since the 1990s. We conclude that in debilitated populations, roads act as threatening factor for brown hare. We recommend establishing large un-dissected areas as a new category of wildlife refuge and to protect these areas from being further fragmented.