Variation of the phase of the 24-h activity period in different large herbivore species under European and African conditions

The variation of daily rhythms were analysed in relation to environmental factors. Activity phases were determined for Przewalski horses (Equus ferus przewalskii), feral domestic horses (Equus caballus), and mouflon (Ovis orientalis musimon) in Europe under semi-natural conditions by storage telemetry (ETHOSYS) and compared to samples from plain zebra (Equus burchelli) and blesbok (Damaliscus dorcas phillipsi) in South African reserves. The activity phase of Przewalski horses was about 16h in the afternoon but delayed during the summer months; feral horses showed similar phases with lower variation. Mouflons had phases of about 14h, delayed until 20h during summer. Zebra showed activity phases after midnight, in the morning, afternoon, and in the evening, but never around noon. The activity phases of blesbok were found at all times of the day. The high variation under African conditions is discussed as resulting from masking by temperature, drought and predation pressure.