Metabolic and thermoregulatory responses to heat and cold in the Djungarian hamster,Phodopus sungorus

Summary Djungarian hamsters,Phodopus sungorus (31.1 g body weight) were exposed to ambient temperatures (T_a) between –35°C and +34°C. They tolerated severe cold stress but were less able to withstand heat. At –35° CT_a, normal body temperature was maintained for several hours. Thereby maximum thermal insulation was calculated at 1.1 g·°C/mW, which is only slightly higher than expected from the hamsters body size. High levels of heat production (60 to 90 m W/g) were maintained for several hours, suggesting that well developed means of heat production are the main reason for cold tolerance of the Djungarian hamster.