A year in the thermal life of a free-ranging herd of springbokAntidorcas marsupialis

Abstract

We used miniature data loggers implanted in the abdominal cavity to measure core body temperatures at 30·min intervals in eight (three males, five females) adult free-ranging springbok Antidorcas marsupialis in their natural habitat, over a period of 11-13 months. The animals were subjected to a nychthemeral range of air temperature that often exceeded 20°C, with an absolute minimum temperature of -6°C and a maximum of 34°C. Abdominal temperature exhibited a low amplitude (~1.2°C) nychthemeral rhythm, with a temperature peak near sunset and a trough shortly after sunrise. The amplitude of the nychthemeral rhythm of body temperature was not correlated with the 24·h range of air temperature. Although mean 24·h body temperatures were positively correlated with corresponding air temperatures, mean daily body temperature increased, on average, by only 0.02°C per 1°C increase in air temperature, so that it was only ~0.3°C higher in summer than in winter. Mean monthly body temperatures were strongly positively correlated with photoperiod and, in parallel with changes in the time of sunrise, the times at which the minimum and maximum body temperatures occurred were shifted ~1.2·h earlier in summer than in winter. Annual and daily variations in body temperature of springbok, like those of other free-living African ungulates, therefore appear to reflect an endogenous rhythm, entrained by the light:dark cycle, but largely independent of fluctuations in the environmental thermal load. Springbok exhibit remarkable homeothermy and do not employ adaptive heterothermy to survive in their natural environment.

Saving energy during hard times: Energetic adaptations of Shetland pony mares

“…Assuming a body temperature of 37.5-38°C, this represents a decrease in body temperature of about 4°C. Other studies on camels (Camelus dromedarius) and springbok (Antidorcas marsupialis) showed slightly higher daily T b amplitudes exceeding 6 and 7°C, respectively (Schmidt-Nielsen et al, 1967;Fuller et al, 2005). However, the amplitudes shown by our ponies were distinctively higher than the normal circadian variations in body temperature for horses [∆1°C (Piccione et al, 2002a)], so we suggest that our ponies likewise used adaptive heterothermy to reduce energy expenditure, characterized by an increased amplitude of the nychthemeral T b rhythm (Fuller et al, 2005).…”

Minimum daily core body temperature in western grey kangaroos decreases as summer advances: a seasonal pattern, or a direct response to water, heat or energy supply?

“…A seasonal change in morning T c and mean 24h T c has also been seen in springbok, a small African antelope (Fuller et al, 2005). Those authors argued that a T c that is lower in winter than in summer might relate to energy availability.…”

Adaptation strategies to seasonal changes in environmental conditions of a domesticated horse breed, the Shetland pony (Equus ferus caballus)

“…Angilletta et al, 2010). Nevertheless, the reduction of T b at night may improve the ponies' capacity to store heat during hot days and thus reduce the energetic cost for thermoregulation (Fuller et al, 2005;Arnold et al, 2006). This type of adaptive heterothermy has been reported in other ungulates such as eland (Taylor and Lyman, 1967), oryx (Taylor, 1969), giraffe (Langman and Maloiy, 1989) and Thomson's as well as Grant's gazelles (Taylor, 1970).…”