Application of a new technique to studying the grazing behaviour of roe deer (Capreolus capreolus)

A new technique of graphical analysis has been developed that is based on plotting the cumulated time spent in one activity against that spent in another. This method has been tested on confined (melatonin-treated and control) and free-living me deer, Capreolus capreolus, in France over a period of 6 months. Implanted melatonin increased the median time spent grazing per selected site during the period April-June from 10 to 12 s, and the proportion of grazing time spent feeding from 58% to 71%. While the bout structure of grazing was generally unpredictable, bouts were sometimes grouped into meals. The latter finding was not apparent from conventional analysis but was revealed by the new technique, which we predict will have wide applicability in behaviour studies where inferences as to motivation are required.