Intolerance amongst deer species at feeding: roe deer are uneasy banqueters.

The function of inter-specific interactions in large herbivore assemblies is under debate. We have studied inter-specific interactions between roe and fallow deer on pastures, to assess whether competition between these Cervidae occurs through behavioural interference. Roe were displaced by fallow deer (i.e. the former moved away from the latter at a distance of >50 m) in 83% of cases (N=127). Ninety-four percentage (N=83) of displacement events occurred while roe deer were feeding; in 50% of these cases (N=78), roe stopped grazing and left the feeding ground. Even when fallow deer did not show any sign of direct aggression to roe, these moved away from fallow in 72% of cases (N=127). Vigilance rate was significantly greater in roe than in fallow deer, irrespectively of the presence of the other species. When roe and fallow deer grazed within 50 m from each other, vigilance rate increased significantly in roe, but not in fallow deer. Roe deer, in a group, were significantly more tolerant of the presence of fallow deer (even in group), than when solitary. Fallow deer seemed to be able to exclude roe deer from feeding sites through behavioural intolerance.