Long-term measurement of roe deer (Capreolus capreolus) (Mammalia: Cervidae) activity using two-axis accelerometers in GPS-collars

The investigation of activity patterns provides crucial information on the ecology of a species, yet there are very few long-term data available from free-ranging species. Here, we present the first continuous activity data of free-ranging roe deer covering an entire calendar year. Six male and five female roe deer in the National Park Bavarian Forest, Germany, were equipped with GPS collars containing a two-axis accelerometer. Activity data were analysed for daily activity patterns and their seasonal changes. Daily activity patterns resembled the patterns described in earlier VHF-telemetry based studies, but instead of a pure active/inactive discrimination, the level of activity was obtained continuously, allowing a more precise study of activity intensity. Activity was observed at all daytimes, but was most intense at twilight. These twilight peaks were less pronounced in winter. The intensity of activity showed stronger seasonal changes than the number and duration of activity bouts. Mean daily activity levels and the number of activity peaks per day were lower in winter than in spring and summer. Mean duration of activity peaks did not change during the year. At all seasons, activity had a significant 24-hour periodicity, but the time of its emphasis changed. The roe deer was most diurnal during winter, and most nocturnal in autumn. In spring and summer, activity was evenly distributed between day and night. Seasonal changes in activity could be explained by seasonal changes in physiological parameters and in environmental changes, especially food supply and climate.