An activity-data-logger for monitoring free-ranging animals

A small (16 cm x 15 cm x 21 cm) solar powered activity-data-logger (ADL) has been developed as a suitable instrument for recording the presence and movements of free-ranging animals. Locomotor activity is recorded by a passive infrared detector (PID), At fixed intervals the signals picked up by the PID are condensed automatically and stored in the ADL. This database can be transferred for further use onto a lap-top or PC, The ADL can store information for up to 80 days and thereafter this information has to be tranferred in order to use the ADL further. A solar-generated accumulator serves as the power supply. The activity of mouflons (Ovis ammon musimon) at a saltlick was recorded between June and September 1993. The ADL's performance was validated by video cameras. We monitored the number of sheep coming into a certain area and the time they stayed on film and this correlated with the findings using the ADL. The daily pattern of the mouflons may be characterised as polymodal with activity periods correlated with dawn and dusk, With decreasing day length in autumn, an additional activity period appeared after midnight, Contrary to popular belief, we registered high proportions of nocturnal activity in every month of the study, Artificial feeding at a particular time of day seems to mask the general influence of the light-dark-cycle as the natural 'Zeitgeber'.