Body temperature daily rhythm adaptations in African savanna elephants (Loxodonta africana).

The savanna elephant is the largest extant mammal and often inhabits hot and arid environments. Due to their large size, it might be expected that elephants have particular physiological adaptations, such as adjustments to the rhythms of their core body temperature (T(b)) to deal with environmental challenges. This study describes for the first time the T(b) daily rhythms in savanna elephants. Our results showed that elephants had lower mean T(b) values (36.2 +/- 0.49 degrees C) than smaller ungulates inhabiting similar environments but did not have larger or smaller amplitudes of T(b) variation (0.40 +/- 0.12 degrees C), as would be predicted by their exposure to large fluctuations in ambient temperature or their large size. No difference was found between the daily T(b) rhythms measured under different conditions of water stress. Peak T(b)'s occurred late in the evening (22:10) which is generally later than in other large mammals ranging in similar environmental conditions.