Arvicoline voles do not possess sophisticated mechanisms to tolerate prolonged fasting and can starve to death in less than 24 h. Two experiments were performed to determine if the common vole (Microtus arvalis) and the tundra vole (M. oeconomus) have thermoregulatory adaptations to enhance survival during food deprivation or in winter, and to reveal the possible presence of ultradian body temperature (T_b) rhythms. Laboratory-bred voles (n = 5–6 for both species) were equipped with intra-abdominal data loggers that registered T_b every 10 min and were subjected to 12-h fasting periods during photophase and scotophase. In addition, 10 animals of both species were placed in outdoor cages at natural ambient temperature (T_a) and their T_b was registered at 3-h intervals between October and June. Fasted voles did not enter torpor, but the average 24-h T_b decreased by 0.2–0.5°C in winter, yielding modest energy savings. The decrease in the T_b correlated with T_a but not photoperiod and could, thus, be interpreted as a response to cold. Tundra voles displayed short T_b rhythms of 3–8 h in the laboratory and their individual T_b fluctuations were synchronized. Arvicolines are suggested as promising models to study T_b rhythms in small mammals.