Effects of summer- and winter-like acclimation on the thermoregulatory behavior of fed and fasted desert hamsters, Phodopus roborovskii

1.Thermoregulatory behavior of fed and fasted desert hamsters (Phodopus roborovskii) acclimated to summer- [16 light (L):8 dark (D), ambient temperature (Ta)=26.5 °C] and winter-like (8L:16D, Ta=10 °C) conditions was studied. Body temperature (Tb), selected temperature and activity were measured in hamsters placed in a thermal gradient system for 48 h.2.Acclimation to winter-like days led to the decrease in body mass by 14% and in body temperature by 1 °C. On the contrary, selected Ta was higher by about 3 °C than in summer-like acclimated hamsters. Fasting affected only temperatures selected by night in winter-like acclimated hamsters.3.Winter-like acclimation led to physiological changes, which may facilitate surviving long winter season. In the face of food shortage, behavioral thermoregulation may markedly reduce the energetic cost of normothermy.