Savanna elephants maintain homeothermy under African heat
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To conserve body water, mammals may reduce evaporative water loss by storing heat, allowing core body temperature to rise more than usual during the day, and to fall more than usual during the cooler night, so demonstrating heterothermy. It has been proposed that elephants are heterothermic, but body temperature never has been measured in elephants over 24 h at environmental temperatures higher than body temperature, where elephants would have to rely on evaporative cooling to maintain homeothermy. We used ingested temperature data loggers to record core temperature of four partly free-ranging savanna elephants exposed to high solar radiation and environmental temperatures that exceeded core temperature (> 36 °C) in their natural habitat. The elephants maintained core temperature at an average 36.6 °C within narrow daily limits of about 1.3 °C. While mean 24-h core temperature increased with maximum air temperature, it did not increase with mean air temperature. Maximum and minimum daily core temperatures also did not change with maximum air temperatures. As a result, core temperature range remained constant despite large variations in daily air temperatures. Contrary to the view that elephants exhibit heterothermy to cope with heat, savanna elephants in their natural habitat with access to adequate resources of food and water, and able to use thermoregulatory behaviour, maintained homeothermy.
KeywordsBiologging Heterothermy Loxodonta africana Thermoregulation
Logistical support was provided by Elephants Without Borders and the University of Witwatersrand’s Brain Function Research Group. The staff of Abu Camp provided field assistance and logistical support. The research was sanctioned by the Botswana Department of Wildlife and National Parks. Financial support for this study was provided by the Paul G. Allen Family Foundation via Elephants Without Borders, the International Fund for Animal Welfare and the University of Pretoria.
Compliance with ethical standards
Conflict of interest
No competing interests declared.
The datasets generated during the current study are available from the corresponding author on reasonable request.
All procedures were approved by the Animal Use and Care Committee at the University of Pretoria (Ref: EC073-12).
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