Dietary partitioning between European roe deer and European brown hare

The European roe deer Capreolus capreolus and the European brown hare Lepus europaeus are two important and widespread herbivores in Europe. In recent decades, roe deer have generally increased throughout Europe, while brown hares have decreased, because of habitat changes caused by agricultural intensification. It is unclear whether resource exploitation by roe deer may favour this decline. The analysis of interspecific dietary patterns could help to assess whether a potential for competition occurs between these herbivores. Through micro-histological analyses of feces, we have assessed food habits, diet selection, and dietary overlap between roe deer and brown hares in a Mediterranean mixed wood-agricultural area, in 2007–2008. We detected significant differences between the composition of diets of these two herbivores. Deciduous and evergreen wood plants were the staple of roe deer (each of them built up >30 % of total diet), while cereals, spontaneous herbs, and graminoids were the staple of hares (each of them built up 23–33 % of diet). These items were selected by roe deer and hares, with seasonal differences in selection indices, likely depending on variation of availability of different food categories. The dietary breadth of roe deer was ca. 2.5 times greater than that of hares; the interspecific dietary overlap was low but increased in winter, and the dietary niche of hares was included in that of roe deer. Our results suggest that dietary and habitat partitioning occurred between roe deer and hares, with wood and open field being their main foraging habitat, respectively. Ecological overlap occurred in winter, when roe deer aggregate in open fields and increase their use of wheat, the main food item of hares. Most likely, abundance of cultivated cereals and spontaneous herbs for hares and presence of wood, providing roe deer with high-quality browse, reduce the potential for interspecific competition and are the key for the coexistence between these herbivores, in Mediterranean agricultural areas.