Effect of ambient temperature on autonomic thermoregulation and activity patterns in the rufous rat-kangaroo (Aepyprymnus rufescens: Marsupialia)

1. Metabolic rate (MR), deep body temperature (Tb) and respiratory frequency (f) were measured in rufous rat-kangaroos in a controlled environment at ambient temperatures (Ta) between 5 and 37 °C. Diurnal variations inTb, total motoric activity and activity pattern were recorded in the same animals in open outdoor enclosures. 2. The lowest MR of 2.74 W kg−0.75 occurred betweenTa=25 to 35 °C. Considerable changes in thermal conductance (C) resulted in a nonlinear increase in MR below the lower critical temperature of 25 °C. Changes inC were attributed to postural changes leading to a reduction in the effective surface area. Panting and saliva spreading were the main mechanisms of heat dissipation atTa above 30 °C. 3. A. rufescens showed a reproducible motoric activity pattern during the night. Total locomotor activity and activity patterns and circadian variations inTb were not affected byTa even below 0 °C. 4. The nest had an important insulative function during the day, the resting period of the animals, but was only seldomly used at night. 5. It is concluded that the locomotor activity may contribute to the regulation ofTb mainly by minor changes in hopping speed and in the duration of resting periods, but not by changes in total activity and activity patterns.