Body temperature, activity patterns and hunting in free-living cheetah: biologging reveals new insights.

As one of the few felids that is predominantly diurnal, cheetahs (Acinonyx jubatus) can be exposed to high heat loads in their natural habitat. Little is known about long-term patterns of body temperature and activity (including hunting) in cheetahs because long-term concurrent measurements of body temperature and activity have never been reported for cheetahs, or, indeed, for any free-living felid. We report here body temperature and locomotor activity measured with implanted data loggers over 7 months in 5 free-living cheetahs in Namibia. Air temperature ranged from a maximum of 39 °C in summer to -2 °C in winter. Cheetahs had higher (∼0.4 °C) maximum 24-h body temperatures, later acrophase (∼1 h), with larger fluctuations in the range of the 24-h body temperature rhythm (approximately 0.4 °C) during a hot-dry period than during a cool-dry period, but maintained homeothermy irrespective of the climatic conditions. As ambient temperatures increased, the cheetahs shifted from a diurnal to a crepuscular activity pattern, with reduced activity between 900 and 1500 hours and increased nocturnal activity. The timing of hunts followed the general pattern of activity; the cheetahs hunted when they were on the move. Cheetahs hunted if an opportunity presented itself; on occasion they hunted in the midday heat or in total darkness (new moon). Biologging revealed insights into cheetah biology that are not accessible by traditional observer-based techniques.