also in the range of 2 3. These results suggest that over the air temperature range in which body temperature of S. macroura was not metabolically defended, metabolic rate during daily torpor was largely a function of body temperature. At air temperatures below 14 ~ at which the torpid animals showed an increase of metabolic rate to regulate body temperature, the negative relationship between metabolic rate and air temperature was a function of the differential between body temperature and air temperature as during normothermia. However, even in thermoregulating animals, the reduction of metabolic rate from normothermia to torpor at a given air temperature can also be explained by temperature effects.
Key words Daily torpor 9 Metabolic rate reduction 9 Temperature 9 Thermoregulation -Marsupial,
Sminthopsis macroura
Abbreviations BM body mass 9 BMR basal metabolic rate -C apparent conductance 9 MR metabolic rate 9 RMR resting metabolic rate-RQ respiratory quotient. Ta air temperature 9 Tb body temperature -T~o lower critical temperature 9 rtc critical air temperature during torpor -TMR metabolic rate during torpor -TNZ thermoneutral zone. A T difference between body temperature and air temperature -l)Oa rate of oxygen consumption