WINTERTIME LOSS OF ULTRADIAN AND CIRCADIAN RHYTHMS OF BODY TEMPERATURE IN THE SUBTERRANEAN EUTHERMIC MOLE VOLE, ELLOBIUS TALPINUS

Subterranean common mole voles, Ellobius talpinus, were implanted with long-term recording electronic thermometers to obtain hourly body temperature (T-b) data during either the wintertime or summertime. The two individuals tested during the summertime had significant circadian and ultradian rhythms in their T-b. Four of the five mole voles tested during the wintertime lacked rhythmicity in their T-b. The fifth individual lacked circadian rhythms but had ultradian rhythms in its T-b. A loss of circadian rhythms in T-b during deep torpor or hibernation has been reported for a few species of mammals. Inasmuch as the mole voles' wintertime T-b remained at euthermic levels, our results show that a loss of circadian body temperature rhythms in mole voles does not require the low T-b of deep torpor or hibernation. A tentative conclusion, based on these few animals, is that in common mole voles the T-b rhythms may disappear during the wintertime even though their T-b remains high. (Author correspondence: eug_nov@ngs.ru)