Habitat modification when scent marking: shrub clearance by roe deer bucks.

Marking activities in many ungulate species involve some aggression directed towards the vegetation which usually affects the understorey layer. Roe deer bucks (Capreolus capreolus) usually defend mating territories within the forest, where they mark the vegetation and the ground by using chemical signals which are typically associated with the visual ones used. Here we describe the presence of roe-made clearings of about 2700 m average size which contained a clump of marks. Roe bucks affected the vegetation mainly by means of fraying and scratching with antlers around the stem of bushes, and defoliation by leaf-biting. The analysis of these activities suggests that their evolution may have been moulded by the effect of shrub clearing. Defoliation affecting more than 50% of leaves was only found within clearings. Also, fraying affected the whole perimeter of the stem and hence desiccated the bushes at higher rates within the clearings than outside. We found only one cleared area per male range, selectively located in a concave land formation. Producing a clump of scent marks within the mating territory may reduce the costs of scent marking, improve the effectiveness of scent guarding and fits well with the hypothesis of reliable scent matching by recipients. The concave shape of the clump, coupled with the cleared vegetation, may improve the perception of visual signals allowing for the location of scents. It is proposed that selection may favour the modification of the habitat as a component of roe deer marking behaviour, via its benefits in improving the broadcasting of visual signals associated with chemical ones.