Oral Presentation- Symposium 12th International Mammalogical Congress

What body temperature patterns reveal about the functioning of large free-living mammals (#280)

Andrea Fuller 1 , Robyn S Hetem 2 , Andrew J Loveridge 3 , David W Macdonald 3 , Richard McFarland 4 , Duncan Mitchell 1 , Shane K Maloney 5
  1. Physiology, University of the Witwatersrand, Johannesburg, South Africa
  2. Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
  3. Zoology, University of Oxford, Oxford, England
  4. Anthropology, University of Wisconsin-Madison, Madison, USA
  5. Physiology, University of Western Australia, Perth, Australia

Although the temperature-regulating system usually acts to maintain mammalian body core temperature high and within narrow daily limits, conspicuous and predictable perturbations to body temperature are evident in large free-living mammals under different physiological states. Through the use of biologging to record body temperatures continuously in large (greater than 5kg) mammals in their natural habitat, we have shown that restriction of food energy or water leads to a trade-off that relaxes thermal regulation and results in heterothermy. Maintaining homeothermy requires a mammal to use energy and water. Dehydrated mammals exhibit higher than normal maximum daily body temperatures, while insufficient energy leads to lower minimum daily body temperatures. This relaxation of body temperature does not appear to be regulated and moves a mammal closer to its thermal limits of performance. Regulated changes in body temperature are evident in fever and during reproduction. Spontaneous fevers in free-living mammals are characterised by an upward shift in body temperature, without changes to the daily rhythm, which may last from days to weeks. In contrast, a progressive reduction in body temperature is evident in female mammals throughout gestation, with parturition characterised by an immediate return to normal body temperature. Body temperature patterns therefore provide a measure of reproductive phenology, infectious illness, malnutrition and dehydration in large free-living mammals. Long-term biologging of body core temperature therefore provides a tool for us to investigate how large mammals work in the natural environment, and how their functioning may be altered when confronting environmental change.